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10 <title>Debian Policy Manual</title>
11 <author><qref id="authors">The Debian Policy Mailing List</qref></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>
76 Informally, the criteria used for inclusion is that the
77 material meet one of the following requirements:
78 <taglist compact="compact">
79 <tag>Standard interfaces</tag>
81 The material presented represents an interface to
82 the packaging system that is mandated for use, and
83 is used by, a significant number of packages, and
84 therefore should not be changed without peer
85 review. Package maintainers can then rely on this
86 interfaces not changing, and the package
87 management software authors need to ensure
88 compatibility with these interface
89 definitions. (Control file and changelog file
90 formats are examples.)
92 <tag>Chosen Convention</tag>
94 If there are a number of technically viable choices
95 that can be made, but one needs to select one of
96 these options for inter-operability. The version
97 number format is one example.
100 Please note that these are not mutually exclusive;
101 selected conventions often become parts of standard
107 The footnotes present in this manual are
108 merely informative, and are not part of Debian policy itself.
112 The appendices to this manual are not necessarily normative,
113 either. Please see <ref id="pkg-scope"> for more information.
117 In the normative part of this manual,
118 the words <em>must</em>, <em>should</em> and
119 <em>may</em>, and the adjectives <em>required</em>,
120 <em>recommended</em> and <em>optional</em>, are used to
121 distinguish the significance of the various guidelines in
122 this policy document. Packages that do not conform to the
123 guidelines denoted by <em>must</em> (or <em>required</em>)
124 will generally not be considered acceptable for the Debian
125 distribution. Non-conformance with guidelines denoted by
126 <em>should</em> (or <em>recommended</em>) will generally be
127 considered a bug, but will not necessarily render a package
128 unsuitable for distribution. Guidelines denoted by
129 <em>may</em> (or <em>optional</em>) are truly optional and
130 adherence is left to the maintainer's discretion.
134 These classifications are roughly equivalent to the bug
135 severities <em>serious</em> (for <em>must</em> or
136 <em>required</em> directive violations), <em>minor</em>,
137 <em>normal</em> or <em>important</em>
138 (for <em>should</em> or <em>recommended</em> directive
139 violations) and <em>wishlist</em> (for <em>optional</em>
142 Compare RFC 2119. Note, however, that these words are
143 used in a different way in this document.
148 Much of the information presented in this manual will be
149 useful even when building a package which is to be
150 distributed in some other way or is intended for local use
156 <heading>New versions of this document</heading>
159 This manual is distributed via the Debian package
160 <package>debian-policy</package>.
164 The current version of this document is also available from
165 the Debian web mirrors at
166 <tt><url name="/doc/debian-policy/"
167 id="http://www.debian.org/doc/debian-policy/"></tt>
168 and from the Debian archive mirrors at
169 <tt><url name="/doc/package-developer/policy.txt.gz"
170 id="http://ftp.debian.org/debian/doc/package-developer/policy.txt.gz"></tt>.
171 Also available from the same directory are several other
172 formats: <file>policy.html.tar.gz</file>, <file>policy.pdf.gz</file>
173 and <file>policy.ps.gz</file>.
177 The <package>debian-policy</package> package also includes the file
178 <file>upgrading-checklist.txt</file> which indicates policy
179 changes between versions of this document.
184 <heading>Authors and Maintainers</heading>
187 Originally called "Debian GNU/Linux Policy Manual", this
188 manual was initially written in 1996 by Ian Jackson.
189 It was revised on November 27th, 1996 by David A. Morris.
190 Christian Schwarz added new sections on March 15th, 1997,
191 and reworked/restructured it in April-July 1997.
192 Christoph Lameter contributed the "Web Standard".
193 Julian Gilbey largely restructured it in 2001.
197 Since September 1998, the responsibility for the contents of
198 this document lies on the <url name="debian-policy mailing list"
199 id="mailto:debian-policy@lists.debian.org">. Proposals
200 are discussed there and inserted into policy after a certain
201 consensus is established.
202 <!-- insert shameless policy-process plug here eventually -->
203 The actual editing is done by a group of maintainers that have
204 no editorial powers. These are the current maintainers:
207 <item>Julian Gilbey</item>
208 <item>Branden Robinson</item>
209 <item>Josip Rodin</item>
210 <item>Manoj Srivastava</item>
215 While the authors of this document have tried hard to avoid
216 typos and other errors, these do still occur. If you discover
217 an error in this manual or if you want to give any
218 comments, suggestions, or criticisms please send an email to
219 the Debian Policy List,
220 <email>debian-policy@lists.debian.org</email>, or submit a
221 bug report against the <tt>debian-policy</tt> package.
225 Please do not try to reach the individual authors or maintainers
226 of the Policy Manual regarding changes to the Policy.
231 <heading>Related documents</heading>
234 There are several other documents other than this Policy Manual
235 that are necessary to fully understand some Debian policies and
240 The external "sub-policy" documents are referred to in:
241 <list compact="compact">
242 <item><ref id="fhs"></item>
243 <item><ref id="virtual_pkg"></item>
244 <item><ref id="menus"></item>
245 <item><ref id="mime"></item>
246 <item><ref id="perl"></item>
247 <item><ref id="maintscriptprompt"></item>
248 <item><ref id="emacs"></item>
253 In addition to those, which carry the weight of policy, there
254 is the Debian Developer's Reference. This document describes
255 procedures and resources for Debian developers, but it is
256 <em>not</em> normative; rather, it includes things that don't
257 belong into the Policy, such as best practices for developers.
261 The Developer's Reference is available in the
262 <package>developers-reference</package> package.
263 It's also available from the Debian web mirrors at
264 <tt><url name="/doc/developers-reference/"
265 id="http://www.debian.org/doc/developers-reference/"></tt>.
273 <heading>The Debian Archive</heading>
276 The Debian GNU/Linux system is maintained and distributed as a
277 collection of <em>packages</em>. Since there are so many of
278 them (currently well over 6000), they are split into
279 <em>sections</em> and given <em>priorities</em> to simplify
280 the handling of them.
284 The effort of the Debian project is to build a free operating
285 system, but not every package we want to make accessible is
286 <em>free</em> in our sense (see the Debian Free Software
287 Guidelines, below), or may be imported/exported without
288 restrictions. Thus, the archive is split into the sections
289 <em>main</em>, <em>non-free</em>, <em>contrib</em>,
290 <em>non-US/main</em>, <em>non-US/non-free</em>, and
291 <em>non-US/contrib</em>. The sections are explained in detail
296 The <em>main</em> and the <em>non-US/main</em> sections
297 together form the <em>Debian GNU/Linux distribution</em>.
301 Packages in the other sections are not considered to be part
302 of the Debian distribution, although we support their use and
303 provide infrastructure for them (such as our bug-tracking
304 system and mailing lists). This Debian Policy Manual applies
305 to these packages as well.</p>
307 <sect id="pkgcopyright">
308 <heading>Package copyright and sections</heading>
310 The aims of this section are:
312 <list compact="compact">
314 to allow us to make as much software available as we can,
317 to allow us to encourage everyone to write free software, and
320 to allow us to make it easy for people to produce
321 CD-ROMs of our system without violating any licenses,
322 import/export restrictions, or any other laws.
327 <heading>The Debian Free Software Guidelines</heading>
329 The Debian Free Software Guidelines (DFSG) form our
330 definition of "free software". These are:
332 <tag>Free Redistribution
335 The license of a Debian component may not restrict any
336 party from selling or giving away the software as a
337 component of an aggregate software distribution
338 containing programs from several different
339 sources. The license may not require a royalty or
340 other fee for such sale.
345 The program must include source code, and must allow
346 distribution in source code as well as compiled form.
351 The license must allow modifications and derived
352 works, and must allow them to be distributed under the
353 same terms as the license of the original software.
355 <tag>Integrity of The Author's Source Code
358 The license may restrict source-code from being
359 distributed in modified form <em>only</em> if the
360 license allows the distribution of "patch files"
361 with the source code for the purpose of modifying the
362 program at build time. The license must explicitly
363 permit distribution of software built from modified
364 source code. The license may require derived works to
365 carry a different name or version number from the
366 original software. (This is a compromise. The Debian
367 Project encourages all authors to not restrict any
368 files, source or binary, from being modified.)
370 <tag>No Discrimination Against Persons or Groups
373 The license must not discriminate against any person
376 <tag>No Discrimination Against Fields of Endeavor
379 The license must not restrict anyone from making use
380 of the program in a specific field of endeavor. For
381 example, it may not restrict the program from being
382 used in a business, or from being used for genetic
385 <tag>Distribution of License
388 The rights attached to the program must apply to all
389 to whom the program is redistributed without the need
390 for execution of an additional license by those
393 <tag>License Must Not Be Specific to Debian
396 The rights attached to the program must not depend on
397 the program's being part of a Debian system. If the
398 program is extracted from Debian and used or
399 distributed without Debian but otherwise within the
400 terms of the program's license, all parties to whom
401 the program is redistributed must have the same
402 rights as those that are granted in conjunction with
405 <tag>License Must Not Contaminate Other Software
408 The license must not place restrictions on other
409 software that is distributed along with the licensed
410 software. For example, the license must not insist
411 that all other programs distributed on the same medium
412 must be free software.
414 <tag>Example Licenses
417 The "GPL," "BSD," and "Artistic" licenses are examples of
418 licenses that we consider <em>free</em>.
424 <heading>The main section</heading>
426 Every package in <em>main</em> and <em>non-US/main</em>
427 must comply with the DFSG (Debian Free Software
432 In addition, the packages in <em>main</em>
433 <list compact="compact">
435 must not require a package outside of <em>main</em>
436 for compilation or execution (thus, the package must
437 not declare a "Depends", "Recommends", or
438 "Build-Depends" relationship on a non-<em>main</em>
442 must not be so buggy that we refuse to support them,
446 must meet all policy requirements presented in this
453 Similarly, the packages in <em>non-US/main</em>
454 <list compact="compact">
456 must not require a package outside of <em>main</em>
457 or <em>non-US/main</em> for compilation or
461 must not be so buggy that we refuse to support them,
464 must meet all policy requirements presented in this
473 <heading>The contrib section</heading>
476 Every package in <em>contrib</em> and
477 <em>non-US/contrib</em> must comply with the DFSG.
481 In addition, the packages in <em>contrib</em> and
482 <em>non-US/contrib</em>
483 <list compact="compact">
485 must not be so buggy that we refuse to support them,
489 must meet all policy requirements presented in this
496 Furthermore, packages in <em>contrib</em> must not require
497 a package in a <em>non-US</em> section for compilation or
502 Examples of packages which would be included in
503 <em>contrib</em> or <em>non-US/contrib</em> are:
504 <list compact="compact">
506 free packages which require <em>contrib</em>,
507 <em>non-free</em> packages or packages which are not
508 in our archive at all for compilation or execution,
512 wrapper packages or other sorts of free accessories for
519 <sect1 id="non-free">
520 <heading>The non-free section</heading>
523 Packages must be placed in <em>non-free</em> or
524 <em>non-US/non-free</em> if they are not compliant with
525 the DFSG or are encumbered by patents or other legal
526 issues that make their distribution problematic.
530 In addition, the packages in <em>non-free</em> and
531 <em>non-US/non-free</em>
532 <list compact="compact">
534 must not be so buggy that we refuse to support them,
538 must meet all policy requirements presented in this
539 manual that it is possible for them to meet.
541 It is possible that there are policy
542 requirements which the package is unable to
543 meet, for example, if the source is
544 unavailable. These situations will need to be
545 handled on a case-by-case basis.
553 <heading>The non-US sections</heading>
556 Non-free programs with cryptographic program code need to
557 be stored on the <em>non-us</em> server because of export
558 restrictions of the U.S.
562 Programs which use patented algorithms that have a
563 restricted license also need to be stored on "non-us",
564 since that is located in a country where it is not allowed
565 to patent algorithms.
569 A package depends on another package which is distributed
570 via the non-us server has to be stored on the non-us
575 <heading>Further copyright considerations</heading>
577 Every package must be accompanied by a verbatim copy of
578 its copyright and distribution license in the file
579 <file>/usr/share/doc/<var>package</var>/copyright</file>
580 (see <ref id="copyrightfile"> for further details).
583 We reserve the right to restrict files from being included
584 anywhere in our archives if
585 <list compact="compact">
587 their use or distribution would break a law,
590 there is an ethical conflict in their distribution or
594 we would have to sign a license for them, or
597 their distribution would conflict with other project
604 Programs whose authors encourage the user to make
605 donations are fine for the main distribution, provided
606 that the authors do not claim that not donating is
607 immoral, unethical, illegal or something similar; in such
608 a case they must go in <em>non-free</em>.</p>
611 Packages whose copyright permission notices (or patent
612 problems) do not even allow redistribution of binaries
613 only, and where no special permission has been obtained,
614 must not be placed on the Debian FTP site and its mirrors
618 Note that under international copyright law (this applies
619 in the United States, too), <em>no</em> distribution or
620 modification of a work is allowed without an explicit
621 notice saying so. Therefore a program without a copyright
622 notice <em>is</em> copyrighted and you may not do anything
623 to it without risking being sued! Likewise if a program
624 has a copyright notice but no statement saying what is
625 permitted then nothing is permitted.</p>
628 Many authors are unaware of the problems that restrictive
629 copyrights (or lack of copyright notices) can cause for
630 the users of their supposedly-free software. It is often
631 worthwhile contacting such authors diplomatically to ask
632 them to modify their license terms. However, this can be a
633 politically difficult thing to do and you should ask for
634 advice on the <tt>debian-legal</tt> mailing list first, as
639 When in doubt about a copyright, send mail to
640 <email>debian-legal@lists.debian.org</email>. Be prepared
641 to provide us with the copyright statement. Software
642 covered by the GPL, public domain software and BSD-like
643 copyrights are safe; be wary of the phrases "commercial
644 use prohibited" and "distribution restricted".
648 <heading>Subsections</heading>
651 The packages in the sections <em>main</em>,
652 <em>contrib</em> and <em>non-free</em> are grouped further
653 into <em>subsections</em> to simplify handling.
657 The section and subsection for each package should be
658 specified in the package's <tt>Section</tt> control
659 record. However, the maintainer of the Debian archive
660 may override this selection to ensure the consistency of
661 the Debian distribution. The <tt>Section</tt> field
662 should be of the form:
663 <list compact="compact">
665 <em>subsection</em> if the package is in the
666 <em>main</em> section,
669 <em>section/subsection</em> if the package is in
670 the <em>contrib</em> or <em>non-free</em> section,
674 <tt>non-US</tt>, <tt>non-US/contrib</tt> or
675 <tt>non-US/non-free</tt> if the package is in
676 <em>non-US/main</em>, <em>non-US/contrib</em> or
677 <em>non-US/non-free</em> respectively.
683 The Debian archive maintainers provide the authoritative
684 list of subsections. At present, they are:
685 <em>admin</em>, <em>base</em>, <em>comm</em>,
686 <em>contrib</em>, <em>devel</em>, <em>doc</em>,
687 <em>editors</em>, <em>electronics</em>, <em>games</em>,
688 <em>graphics</em>, <em>hamradio</em>,
689 <em>interpreters</em>, <em>libs</em>, <em>mail</em>,
690 <em>math</em>, <em>misc</em>, <em>net</em>, <em>news</em>,
691 <em>non-US</em>, <em>non-free</em>, <em>oldlibs</em>,
692 <em>otherosfs</em>, <em>science</em>, <em>shells</em>,
693 <em>sound</em>, <em>tex</em>, <em>text</em>,
694 <em>utils</em>, <em>web</em>, <em>x11</em>.
698 <heading>Priorities</heading>
701 Each package should have a <em>priority</em> value, which is
702 included in the package's <em>control record</em>. This
703 information is used by the Debian package management tools
704 to separate high-priority packages from less-important
708 The following <em>priority levels</em> are recognised by the
709 Debian package management tools.
711 <tag><tt>required</tt></tag>
713 Packages which are necessary for the proper
714 functioning of the system. You must not remove these
715 packages or your system may become totally broken and
716 you may not even be able to use <prgn>dpkg</prgn> to
717 put things back. Systems with only the
718 <tt>required</tt> packages are probably unusable, but
719 they do have enough functionality to allow the
720 sysadmin to boot and install more software.
722 <tag><tt>important</tt></tag>
724 Important programs, including those which one would
725 expect to find on any Unix-like system. If the
726 expectation is that an experienced Unix person who
727 found it missing would say "What on earth is going on,
728 where is <prgn>foo</prgn>?", it must be an
729 <tt>important</tt> package.<footnote>
730 This is an important criterion because we are
731 trying to produce, amongst other things, a free
734 Other packages without which the system will not run
735 well or be usable must also have priority
736 <tt>important</tt>. This does
737 <em>not</em> include Emacs, the X Window System, TeX
738 or any other large applications. The
739 <tt>important</tt> packages are just a bare minimum of
740 commonly-expected and necessary tools.
742 <tag><tt>standard</tt></tag>
744 These packages provide a reasonably small but not too
745 limited character-mode system. This is what will be
746 installed by default if the user doesn't select anything
747 else. It doesn't include many large applications.
749 <tag><tt>optional</tt></tag>
751 (In a sense everything that isn't required is
752 optional, but that's not what is meant here.) This is
753 all the software that you might reasonably want to
754 install if you didn't know what it was and don't have
755 specialized requirements. This is a much larger system
756 and includes the X Window System, a full TeX
757 distribution, and many applications. Note that
758 optional packages should not conflict with each other.
760 <tag><tt>extra</tt></tag>
762 This contains all packages that conflict with others
763 with required, important, standard or optional
764 priorities, or are only likely to be useful if you
765 already know what they are or have specialised
772 Packages must not depend on packages with lower priority
773 values (excluding build-time dependencies). In order to
774 ensure this, the priorities of one or more packages may need
780 <heading>Binary packages</heading>
783 The Debian GNU/Linux distribution is based on the Debian
784 package management system, called <prgn>dpkg</prgn>. Thus,
785 all packages in the Debian distribution must be provided
786 in the <tt>.deb</tt> file format.</p>
790 <heading>The package name</heading>
793 Every package must have a name that's unique within the Debian
797 Package names must consist only of lower case letters
798 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
799 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
800 They must be at least two characters long and must start
801 with an alphanumeric character.
805 The package name is part of the file name of the
806 <tt>.deb</tt> file and is included in the control field
812 <heading>The maintainer of a package</heading>
814 Every package must have a Debian maintainer (the
815 maintainer may be one person or a group of people
816 reachable from a common email address, such as a mailing
817 list). The maintainer is responsible for ensuring that
818 the package is placed in the appropriate distributions.
822 The maintainer must be specified in the
823 <tt>Maintainer</tt> control field with their correct name
824 and a working email address. If one person maintains
825 several packages, he/she should try to avoid having
826 different forms of their name and email address in
827 the <tt>Maintainer</tt> fields of those packages.
831 If the maintainer of a package quits from the Debian
832 project, "Debian QA Group"
833 <email>packages@qa.debian.org</email> takes over the
834 maintainership of the package until someone else
835 volunteers for that task. These packages are called
836 <em>orphaned packages</em>.<footnote>
837 The detailed procedure for doing this gracefully can
838 be found in the Debian Developer's Reference,
839 see <ref id="related">.
846 <heading>The description of a package</heading>
849 Every Debian package must have an extended description
850 stored in the appropriate field of the control record.</p>
853 The description should be written so that it gives the
854 system administrator enough information to decide whether
855 to install the package. This description should not just
856 be copied verbatim from the program's documentation.
857 Instructions for configuring or using the package should
858 not be included (that is what installation scripts,
859 manual pages, info files, etc., are for). Copyright
860 statements and other administrivia should not be included
861 either (that is what the copyright file is for).
865 Please refer to <ref id="descriptions"> for more information.
872 <heading>Dependencies</heading>
875 Every package must specify the dependency information
876 about other packages that are required for the first to
880 For example, a dependency entry must be provided for any
881 shared libraries required by a dynamically-linked executable
882 binary in a package.</p>
885 Packages are not required to declare any dependencies they
886 have on other packages which are marked <tt>Essential</tt>
887 (see below), and should not do so unless they depend on a
888 particular version of that package.</p>
891 Sometimes, a package requires another package to be installed
892 <em>and</em> configured before it can be installed. In this
893 case, you must specify a <tt>Pre-Depends</tt> entry for
897 You should not specify a <tt>Pre-Depends</tt> entry for a
898 package before this has been discussed on the
899 <tt>debian-devel</tt> mailing list and a consensus about
900 doing that has been reached.</p></sect1>
903 <sect1 id="virtual_pkg">
904 <heading>Virtual packages</heading>
907 Sometimes, there are several packages which offer
908 more-or-less the same functionality. In this case, it's
909 useful to define a <em>virtual package</em> whose name
910 describes that common functionality. (The virtual
911 packages only exist logically, not physically; that's why
912 they are called <em>virtual</em>.) The packages with this
913 particular function will then <em>provide</em> the virtual
914 package. Thus, any other package requiring that function
915 can simply depend on the virtual package without having to
916 specify all possible packages individually.</p>
919 All packages should use virtual package names where
920 appropriate, and arrange to create new ones if necessary.
921 They should not use virtual package names (except privately,
922 amongst a cooperating group of packages) unless they have
923 been agreed upon and appear in the list of virtual package
924 names. (See also <ref id="virtual">)</p>
927 The latest version of the authoritative list of virtual
928 package names can be found in the <tt>debian-policy</tt> package.
929 It's also available from the Debian web mirrors at
930 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
931 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>
932 and from the Debian archive mirrors at
933 <tt><url name="/doc/package-developer/virtual-package-names-list.txt"
934 id="http://ftp.debian.org/debian/doc/package-developer/virtual-package-names-list.txt"></tt>.
938 The procedure for updating the list is described in the preface
945 <heading>Base system</heading>
948 The <tt>base system</tt> is a minimum subset of the Debian
949 GNU/Linux system that is installed before everything else
950 on a new system. Thus, only very few packages are allowed
951 to go into the <tt>base</tt> section to keep the required
952 disk usage very small.</p>
955 Most of these packages will have the priority value
956 <tt>required</tt> or at least <tt>important</tt>, and many
957 of them will be tagged <tt>essential</tt> (see below).</p>
964 <heading>Essential packages</heading>
967 Some packages are tagged <tt>essential</tt>. (They have
968 <tt>Essential: yes</tt> in their package control record.)
969 This flag is used for packages that are <em>essential</em>
973 Since these packages cannot be easily removed (one has to
974 specify an extra <em>force option</em> to
975 <prgn>dpkg</prgn> to do so), this flag must not be used
976 unless absolutely necessary. A shared library package
977 must not be tagged <tt>essential</tt>; dependencies will
978 prevent its premature removal, and we need to be able to
979 remove it when it has been superseded.
983 Since dpkg will not prevent upgrading of other packages
984 while an <tt>essential</tt> package is in an unconfigured
985 state, all <tt>essential</tt> packages must supply all of
986 their core functionality even when unconfigured. If the
987 package cannot satisfy this requirement it must not be
988 tagged as essential, and any packages depending on this
989 package must instead have explicit dependency fields as
994 You must not tag any packages <tt>essential</tt> before
995 this has been discussed on the <tt>debian-devel</tt>
996 mailing list and a consensus about doing that has been
1001 <heading>Tasks</heading>
1004 The Debian install process allows the user to choose from
1005 a number of common tasks which a Debian system can be used to
1006 perform. Selecting a task with <prgn>tasksel</prgn> causes
1007 a set of packages that are useful in performing that task to be
1012 This set of packages is all available packages which have the
1013 name of the selected task in the <tt>Task</tt> field of their
1014 control file. The format of this field is a list of tasks,
1015 separated by commas.
1019 You should not tag any packages as belonging to a task
1020 before this has been discussed on the
1021 <em>debian-devel</em> mailing list and a consensus about
1022 doing that has been reached.
1026 For third parties (and historical reasons), tasksel also
1027 supports constructing tasks based on <em>task
1028 packages</em>. These are packages whose names begin with
1029 <em>task-</em>. Task packages should not be included in the
1034 <sect1 id="maintscripts">
1035 <heading>Maintainer Scripts</heading>
1038 The package installation scripts should avoid producing
1039 output which it is unnecessary for the user to see and
1040 should rely on <prgn>dpkg</prgn> to stave off boredom on
1041 the part of a user installing many packages. This means,
1042 amongst other things, using the <tt>--quiet</tt> option on
1043 <prgn>install-info</prgn>.</p>
1046 Errors which occur during the execution of an installation
1047 script must be checked and the installation must not
1048 continue after an error.
1052 Note that in general <ref id="scripts"> applies to package
1053 maintainer scripts, too.
1057 You should not use <prgn>dpkg-divert</prgn> on a file
1058 belonging to another package without consulting the
1059 maintainer of that package first.
1063 All packages which supply an instance of a common command
1064 name (or, in general, filename) should generally use
1065 <prgn>update-alternatives</prgn>, so that they may be
1066 installed together. If <prgn>update-alternatives</prgn>
1067 is not used, then each package must use
1068 <tt>Conflicts</tt> to ensure that other packages are
1069 de-installed. (In this case, it may be appropriate to
1070 specify a conflict against earlier versions of something
1071 that previously did not use
1072 <prgn>update-alternatives</prgn>; this is an exception to
1073 the usual rule that versioned conflicts should be
1078 <sect2 id="maintscriptprompt">
1079 <heading>Prompting in maintainer scripts</heading>
1081 Package maintainer scripts may prompt the user if
1082 necessary. Prompting may be accomplished by
1084 From the Jargon file: by hand 2. By extension,
1085 writing code which does something in an explicit or
1086 low-level way for which a presupplied library
1087 (<em>debconf, in this instance</em>) routine ought
1088 to have been available.
1089 </footnote> (but this is deprecated), or by communicating
1090 through a program which conforms to the Debian Configuration
1091 management specification, version 2 or higher, such as
1092 <prgn>debconf</prgn><footnote>
1094 6% of Debian packages [see <url
1095 id="http://auric.debian.org/%7Ejoeyh/debconf-stats/data/"
1096 name="Debconf stats">] currently use
1097 <package>debconf</package> to prompt the user at
1098 install time, and this number is growing daily. The
1099 benefits of using debconf are briefly explained at
1101 id="http://kitenet.net/doc/debconf-doc/introduction.html"
1102 name="Debconf introduction">; they include
1103 preconfiguration, (mostly) noninteractive
1104 installation, elimination of redundant prompting,
1105 consistency of user interface, etc.
1109 With this increasing number of packages using
1110 <package>debconf</package>, plus the existence of a
1111 nascent second implementation of the Debian
1112 configuration management system
1113 (<package>cdebconf</package>), and the stabilization
1114 of the protocol these things use, the time has
1115 finally come to reflect the use of these things in
1122 The Debian Configuration management specification is included
1123 in the <file>debconf_specification</file> files in the
1124 <package>debian-policy</package> package.
1125 It is also available from the Debian web mirrors at
1126 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1127 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>
1128 and from the Debian archive mirrors at
1129 <tt><url name="/doc/package-developer/debconf_specification.txt.gz"
1130 id="http://ftp.debian.org/debian/doc/package-developer/debconf_specification.txt.gz"></tt>.
1134 Packages which use the Debian Configuration management
1135 specification may contain an additional
1136 <prgn>config</prgn> script and a <tt>templates</tt>
1137 file in their control archive. The <prgn>config</prgn>
1138 script might be run before the <prgn>preinst</prgn>
1139 script, and before the package is unpacked or any of its
1140 dependencies or pre-dependancies are satisfied.
1141 Therefore it must work using only the tools present in
1142 <em>essential</em> packages.<footnote>
1143 <package>Debconf</package> or another tool that
1144 implements the Debian Configuration management
1145 specification will also be installed, and any
1146 versioned dependencies on it will be satisfied
1147 before preconfiguration begins.
1152 Packages should try to minimize the amount of prompting
1153 they need to do, and they should ensure that the user
1154 will only ever be asked each question once. This means
1155 that packages should try to use appropriate shared
1156 configuration files (such as <file>/etc/papersize</file> and
1157 <file>/etc/news/server</file>), and shared
1158 <package>debconf</package> variables rather than each
1159 prompting for their own list of required pieces of
1164 It also means that an upgrade should not ask the same
1165 questions again, unless the user has used <tt>dpkg
1166 --purge</tt> to remove the package's configuration. The
1167 answers to configuration questions should be stored in an
1168 appropriate place in <file>/etc</file> so that the user can
1169 modify them, and how this has been done should be
1173 If a package has a vitally important piece of
1174 information to pass to the user (such as "don't run me
1175 as I am, you must edit the following configuration files
1176 first or you risk your system emitting badly-formatted
1177 messages"), it should display this in the
1178 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1179 prompt the user to hit return to acknowledge the
1180 message. Copyright messages do not count as vitally
1181 important (they belong in
1182 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1183 neither do instructions on how to use a program (these
1184 should be in on-line documentation, where all the users
1188 Any necessary prompting should almost always be confined
1189 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1190 script. If it is done in the <prgn>postinst</prgn>, it
1191 should be protected with a conditional so that
1192 unnecessary prompting doesn't happen if a package's
1193 installation fails and the <prgn>postinst</prgn> is
1194 called with <tt>abort-upgrade</tt>,
1195 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.</p>
1200 <heading>Source packages</heading>
1202 <sect1 id="standardsversion">
1203 <heading>Standards conformance</heading>
1206 In the source package's <tt>Standards-Version</tt> control
1207 field, you should specify the most recent version number
1208 of this policy document with which your package complied
1209 when it was last updated. The current version number is
1214 This information may be used to file bug reports
1215 automatically if your package becomes too much out of
1220 The version number has four components: major and minor
1221 version number and major and minor patch level. When the
1222 standards change in a way that requires every package to
1223 change the major number will be changed. Significant
1224 changes that will require work in many packages will be
1225 signaled by a change to the minor number. The major patch
1226 level will be changed for any change to the meaning of the
1227 standards, however small; the minor patch level will be
1228 changed when only cosmetic, typographical or other edits
1229 are made which neither change the meaning of the document
1230 nor affect the contents of packages.</p>
1233 Thus only the first three components of the policy version
1234 are significant in the <em>Standards-Version</em> control
1235 field, and so either these three components or the all
1236 four components may be specified.<footnote>
1237 In the past, people specified the full version number
1238 in the Standards-Version field, for example "2.3.0.0".
1239 Since minor patch-level changes don't introduce new
1240 policy, it was thought it would be better to relax
1241 policy and only require the first 3 components to be
1242 specified, in this example "2.3.0". All four
1243 components may still be used if someone wishes to do
1249 You should regularly, and especially if your package has
1250 become out of date, check for the newest Policy Manual
1251 available and update your package, if necessary. When your
1252 package complies with the new standards you should update the
1253 <tt>Standards-Version</tt> source package field and
1254 release it.<footnote>
1255 See the file <file>upgrading-checklist</file> for
1256 information about policy which has changed between
1257 different versions of this document.
1263 <sect1 id="pkg-relations">
1264 <heading>Package relationships</heading>
1267 Source packages should specify which binary packages they
1268 require to be installed or not to be installed in order to
1269 build correctly. For example, if building a package
1270 requires a certain compiler, then the compiler should be
1271 specified as a build-time dependency.
1275 It is not necessary to explicitly specify build-time
1276 relationships on a minimal set of packages that are always
1277 needed to compile, link and put in a Debian package a
1278 standard "Hello World!" program written in C or C++. The
1279 required packages are called <em>build-essential</em>, and
1280 an informational list can be found in
1281 <file>/usr/share/doc/build-essential/list</file> (which is
1282 contained in the <tt>build-essential</tt>
1285 <list compact="compact">
1287 This allows maintaining the list separately
1288 from the policy documents (the list does not
1289 need the kind of control that the policy
1293 Having a separate package allows one to install
1294 the build-essential packages on a machine, as
1295 well as allowing other packages such as tasks to
1296 require installation of the build-essential
1297 packages using the depends relation.
1300 The separate package allows bug reports against
1301 the list to be categorized separately from
1302 the policy management process in the BTS.
1309 When specifying the set of build-time dependencies, one
1310 should list only those packages explicitly required by the
1311 build. It is not necessary to list packages which are
1312 required merely because some other package in the list of
1313 build-time dependencies depends on them.<footnote>
1314 The reason for this is that dependencies change, and
1315 you should list all those packages, and <em>only</em>
1316 those packages that <em>you</em> need directly. What
1317 others need is their business. For example, if you
1318 only link against <file>libimlib</file>, you will need to
1319 build-depend on <package>libimlib2-dev</package> but
1320 not against any <tt>libjpeg*</tt> packages, even
1321 though <tt>libimlib2-dev</tt> currently depends on
1322 them: installation of <package>libimlib2-dev</package>
1323 will automatically ensure that all of its run-time
1324 dependencies are satisfied.
1329 If build-time dependencies are specified, it must be
1330 possible to build the package and produce working binaries
1331 on a system with only essential and build-essential
1332 packages installed and also those required to satisfy the
1333 build-time relationships (including any implied
1334 relationships). In particular, this means that version
1335 clauses should be used rigorously in build-time
1336 relationships so that one cannot produce bad or
1337 inconsistently configured packages when the relationships
1338 are properly satisfied.
1342 <ref id="relationships"> explains the technical details.
1346 <heading>Changes to the upstream sources</heading>
1349 If changes to the source code are made that are not
1350 specific to the needs of the Debian system, they should be
1351 sent to the upstream authors in whatever form they prefer
1352 so as to be included in the upstream version of the
1356 If you need to configure the package differently for
1357 Debian or for Linux, and the upstream source doesn't
1358 provide a way to do so, you should add such configuration
1359 facilities (for example, a new <prgn>autoconf</prgn> test
1360 or <tt>#define</tt>) and send the patch to the upstream
1361 authors, with the default set to the way they originally
1362 had it. You can then easily override the default in your
1363 <file>debian/rules</file> or wherever is appropriate.</p>
1366 You should make sure that the <prgn>configure</prgn> utility
1367 detects the correct architecture specification string
1368 (refer to <ref id="arch-spec"> for details).</p>
1371 If you need to edit a <prgn>Makefile</prgn> where
1372 GNU-style <prgn>configure</prgn> scripts are used, you
1373 should edit the <file>.in</file> files rather than editing the
1374 <prgn>Makefile</prgn> directly. This allows the user to
1375 reconfigure the package if necessary. You should
1376 <em>not</em> configure the package and edit the generated
1377 <prgn>Makefile</prgn>! This makes it impossible for
1378 someone else to later reconfigure the package.</p>
1381 You should document your changes and updates to the source
1382 package properly in the <file>debian/changelog</file> file.
1383 For more information, please see <ref id="changelogs">.
1389 <heading>Error trapping in makefiles</heading>
1392 When <prgn>make</prgn> invokes a command in a makefile
1393 (including your package's upstream makefiles and
1394 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1395 means that <prgn>sh</prgn>'s usual bad error handling
1396 properties apply: if you include a miniature script as one
1397 of the commands in your makefile you'll find that if you
1398 don't do anything about it then errors are not detected
1399 and <prgn>make</prgn> will blithely continue after
1403 Every time you put more than one shell command (this
1404 includes using a loop) in a makefile command you
1405 must make sure that errors are trapped. For
1406 simple compound commands, such as changing directory and
1407 then running a program, using <tt>&&</tt> rather
1408 than semicolon as a command separator is sufficient. For
1409 more complex commands including most loops and
1410 conditionals you should include a separate <tt>set -e</tt>
1411 command at the start of every makefile command that's
1412 actually one of these miniature shell scripts.</p></sect1>
1416 <heading>Obsolete constructs and libraries</heading>
1419 The include file <tt><varargs.h></tt> is
1420 provided to support end-users compiling very old software;
1421 the library <tt>libtermcap</tt> is provided to support the
1422 execution of software which has been linked against it
1423 (either old programs or those such as Netscape which are
1424 only available in binary form).</p>
1427 Debian packages should be patched to use
1428 <tt><stdarg.h></tt> and <tt>ncurses</tt>
1435 <chapt id="controlfields"><heading>Control files and their fields</heading>
1438 Many of the tools in the package management suite manipulate
1439 data represented in a common format, known as <em>control
1440 data</em>. The data is often stored in <em>control
1441 files</em>. Binary and source packages have control files,
1442 and the <file>.changes</file> files which control the installation
1443 of uploaded files are also in control file format.
1444 <prgn>dpkg</prgn>'s internal databases are in a similar
1448 <sect id="controlsyntax"><heading>Syntax of control files</heading>
1451 A control file consists of one or more paragraphs of fields.
1452 The paragraphs are separated by blank lines. Some control
1453 files allow only one paragraph; others allow several, in
1454 which case each paragraph usually refers to a different
1455 package. (For example, in source packages, the first
1456 paragraph refers to the source package, and later paragraphs
1457 refer to binary packages generated from the source.)
1461 Each paragraph consists of a series of data fields; each
1462 field consists of the field name, followed by a colon and
1463 then the data/value associated with that field. It ends at
1464 the end of the line. Horizontal whitespace (spaces and
1465 tabs) may occur immediately before or after the value and is
1466 ignored there; it is conventional to put a single space
1467 after the colon. For example, a field might be:
1468 <example compact="compact">
1471 the field name is <tt>Package</tt> and the field value
1476 Some fields' values may span several lines; in this case
1477 each continuation line <em>must</em> start with a space or
1478 tab. Any trailing spaces or tabs at the end of individual
1479 lines of a field value are ignored.
1483 Except where otherwise stated only a single line of data is
1484 allowed and whitespace is not significant in a field body.
1485 Whitespace must not appear inside names (of packages,
1486 architectures, files or anything else) or version numbers,
1487 or between the characters of multi-character version
1492 Field names are not case-sensitive, but it is usual to
1493 capitalize the field names using mixed case as shown below.
1497 Blank lines, or lines consisting only of spaces and tabs,
1498 are not allowed within field values or between fields - that
1499 would mean a new paragraph.
1504 <sect><heading>List of fields</heading>
1506 This list here is not supposed to be exhaustive. Most fields
1507 are dealt with elsewhere in this document.
1509 <sect1 id="f-Package"><heading><tt>Package</tt>
1513 The name of the binary package. Package names consist of
1514 lower case letters (<tt>a-z</tt>), digits (<tt>0-9</tt>),
1515 plus (<tt>+</tt>) and minus (<tt>-</tt>) signs, and
1516 periods (<tt>.</tt>).
1520 They must be at least two characters long and must start
1521 with an alphanumeric character. The use of lowercase
1522 package names is required unless the package you're
1523 building (or referring to, in other fields) is already
1524 using uppercase characters.</p>
1527 <sect1 id="f-Version"><heading><tt>Version</tt>
1531 This lists the source or binary package's version number -
1532 see <ref id="versions">.
1538 id="f-Standards-Version"><heading><tt>Standards-Version</tt>
1542 The most recent version of the standards (the policy
1543 manual and associated texts) with which the package
1544 complies. This is updated manually when editing the
1545 source package to conform to newer standards; it can
1546 sometimes be used to tell when a package needs attention.
1547 Its format is described above; see
1548 <ref id="standardsversion">.
1553 <sect1 id="f-Distribution"><heading><tt>Distribution</tt>
1557 In a <file>.changes</file> file or parsed changelog output
1558 this contains the (space-separated) name(s) of the
1559 distribution(s) where this version of the package should
1560 be installed. Valid distributions are determined by the
1561 archive maintainers.<footnote>
1562 Current distribution names are:
1563 <taglist compact="compact">
1564 <tag><em>stable</em></tag>
1566 This is the current "released" version of Debian
1567 GNU/Linux. Once the distribution is
1568 <em>stable</em> only security fixes and other
1569 major bug fixes are allowed. When changes are
1570 made to this distribution, the release number is
1571 increased (for example: 2.2r1 becomes 2.2r2 then
1575 <tag><em>unstable</em></tag>
1577 This distribution value refers to the
1578 <em>developmental</em> part of the Debian
1579 distribution tree. New packages, new upstream
1580 versions of packages and bug fixes go into the
1581 <em>unstable</em> directory tree. Download from
1582 this distribution at your own risk.
1585 <tag><em>testing</em></tag>
1587 This distribution value refers to the
1588 <em>testing</em> part of the Debian distribution
1589 tree. It receives its packages from the
1590 unstable distribution after a short time lag to
1591 ensure that there are no major issues with the
1592 unstable packages. It is less prone to breakage
1593 than unstable, but still risky. It is not
1594 possible to upload packages directly to
1598 <tag><em>frozen</em></tag>
1600 From time to time, the <em>testing</em>
1601 distribution enters a state of "code-freeze" in
1602 anticipation of release as a <em>stable</em>
1603 version. During this period of testing only
1604 fixes for existing or newly-discovered bugs will
1605 be allowed. The exact details of this stage are
1606 determined by the Release Manager.
1609 <tag><em>experimental</em></tag>
1611 The packages with this distribution value are
1612 deemed by their maintainers to be high
1613 risk. Oftentimes they represent early beta or
1614 developmental packages from various sources that
1615 the maintainers want people to try, but are not
1616 ready to be a part of the other parts of the
1617 Debian distribution tree. Download at your own
1622 You should list <em>all</em> distributions that the
1623 package should be installed into.
1633 <chapt id="versions"><heading>Version numbering</heading>
1636 Every package has a version number recorded in its
1637 <tt>Version</tt> control file field.
1641 The package management system imposes an ordering on version
1642 numbers, so that it can tell whether packages are being up- or
1643 downgraded and so that package system front end applications
1644 can tell whether a package it finds available is newer than
1645 the one installed on the system. The version number format
1646 has the most significant parts (as far as comparison is
1647 concerned) at the beginning.
1651 The version number format is:
1652 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
1656 The three components here are:
1658 <tag><var>epoch</var></tag>
1661 This is a single (generally small) unsigned integer. It
1662 may be omitted, in which case zero is assumed. If it is
1663 omitted then the <var>upstream_version</var> may not
1668 It is provided to allow mistakes in the version numbers
1669 of older versions of a package, and also a package's
1670 previous version numbering schemes, to be left behind.
1674 <tag><var>upstream_version</var></tag>
1677 This is the main part of the version number. It is
1678 usually the version number of the original ("upstream")
1679 package from which the <file>.deb</file> file has been made,
1680 if this is applicable. Usually this will be in the same
1681 format as that specified by the upstream author(s);
1682 however, it may need to be reformatted to fit into the
1683 package management system's format and comparison
1688 The comparison behavior of the package management system
1689 with respect to the <var>upstream_version</var> is
1690 described below. The <var>upstream_version</var>
1691 portion of the version number is mandatory.
1695 The <var>upstream_version</var> may contain only
1696 alphanumerics<footnote>
1697 Alphanumerics are <tt>A-Za-z0-9</tt> only.
1699 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
1700 <tt>:</tt> (full stop, plus, hyphen, colon) and should
1701 start with a digit. If there is no
1702 <var>debian_revision</var> then hyphens are not allowed;
1703 if there is no <var>epoch</var> then colons are not
1707 <tag><var>debian_revision</var></tag>
1710 This part of the version number specifies the version of
1711 the Debian package based on the upstream version. It
1712 may contain only alphanumerics and the characters
1713 <tt>+</tt> and <tt>.</tt> (plus and full stop) and is
1714 compared in the same way as the
1715 <var>upstream_version</var> is.
1719 It is optional; if it isn't present then the
1720 <var>upstream_version</var> may not contain a hyphen.
1721 This format represents the case where a piece of
1722 software was written specifically to be turned into a
1723 Debian package, and so there is only one "debianization"
1724 of it and therefore no revision indication is required.
1728 It is conventional to restart the
1729 <var>debian_revision</var> at <tt>1</tt> each time the
1730 <var>upstream_version</var> is increased.
1734 The package management system will break the version
1735 number apart at the last hyphen in the string (if there
1736 is one) to determine the <var>upstream_version</var> and
1737 <var>debian_revision</var>. The absence of a
1738 <var>debian_revision</var> compares earlier than the
1739 presence of one (but note that the
1740 <var>debian_revision</var> is the least significant part
1741 of the version number).
1748 The <var>upstream_version</var> and <var>debian_revision</var>
1749 parts are compared by the package management system using the
1754 The strings are compared from left to right.
1758 First the initial part of each string consisting entirely of
1759 non-digit characters is determined. These two parts (one of
1760 which may be empty) are compared lexically. If a difference
1761 is found it is returned. The lexical comparison is a
1762 comparison of ASCII values modified so that all the letters
1763 sort earlier than all the non-letters.
1767 Then the initial part of the remainder of each string which
1768 consists entirely of digit characters is determined. The
1769 numerical values of these two parts are compared, and any
1770 difference found is returned as the result of the comparison.
1771 For these purposes an empty string (which can only occur at
1772 the end of one or both version strings being compared) counts
1777 These two steps (comparing and removing initial non-digit
1778 strings and initial digit strings) are repeated until a
1779 difference is found or both strings are exhausted.
1783 Note that the purpose of epochs is to allow us to leave behind
1784 mistakes in version numbering, and to cope with situations
1785 where the version numbering scheme changes. It is
1786 <em>not</em> intended to cope with version numbers containing
1787 strings of letters which the package management system cannot
1788 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
1789 silly orderings (the author of this manual has heard of a
1790 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
1791 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
1792 <tt>2</tt> and so forth).
1796 If an upstream package has problematic version numbers they
1797 should be converted to a sane form for use in the
1798 <tt>Version</tt> field.
1802 <heading>Version numbers based on dates</heading>
1804 In general, Debian packages should use the same version
1805 numbers as the upstream sources.</p>
1808 However, in some cases where the upstream version number is
1809 based on a date (e.g., a development "snapshot" release) the
1810 package management system cannot handle these version
1811 numbers without epochs. For example, dpkg will consider
1812 "96May01" to be greater than "96Dec24".</p>
1815 To prevent having to use epochs for every new upstream
1816 version, the version number should be changed to the
1817 following format in such cases: "19960501", "19961224". It
1818 is up to the maintainer whether he/she wants to bother the
1819 upstream maintainer to change the version numbers upstream,
1823 Note that other version formats based on dates which are
1824 parsed correctly by the package management system should
1825 <em>not</em> be changed.</p>
1828 Native Debian packages (i.e., packages which have been
1829 written especially for Debian) whose version numbers include
1830 dates should always use the "YYYYMMDD" format.</p>
1834 <chapt id="miscellaneous"><heading>Packaging Considerations</heading>
1836 <sect id="timestamps"><heading>Time Stamps</heading>
1838 Maintainers should preserve the modification times of the
1839 upstream source files in a package, as far as is reasonably
1841 The rationale is that there is some information conveyed
1842 by knowing the age of the file, for example, you could
1843 recognize that some documentation is very old by looking
1844 at the modification time, so it would be nice if the
1845 modification time of the upstream source would be
1851 <sect id="debianrules"><heading><file>debian/rules</file> - the
1852 main building script</heading>
1855 This file must be an executable makefile, and contains the
1856 package-specific recipes for compiling the package and
1857 building binary package(s) from the source.
1861 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1862 so that it can be invoked by saying its name rather than
1863 invoking <prgn>make</prgn> explicitly.
1867 Since an interactive <file>debian/rules</file> script makes it
1868 impossible to auto-compile that package and also makes it
1869 hard for other people to reproduce the same binary
1870 package, all <em>required targets</em> MUST be
1871 non-interactive. At a minimum, required targets are the
1872 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1873 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1874 <em>binary-indep</em>, and <em>build</em>. It also follows
1875 that any target that these targets depend on must also be
1880 The required and optional targets are as follows:
1882 <tag><tt>build</tt>, <tt>build-arch</tt> (optional),
1883 <tt>build-indep</tt> (optional)</tag>
1886 The <tt>build</tt> target should perform all
1887 non-interactive configuration and compilation of the
1888 package. If a package has an interactive pre-build
1889 configuration routine, the Debianized source package
1890 must either be built after this has taken place (so
1891 that the binary package can be built without rerunning
1892 the configuration) or the configuration routine
1893 modified to become non-interactive. (The latter is
1894 preferable if there are architecture-specific features
1895 detected by the configuration routine.)
1899 For some packages, notably ones where the same
1900 source tree is compiled in different ways to produce
1901 two binary packages, the <tt>build</tt> target
1902 does not make much sense. For these packages it is
1903 good enough to provide two (or more) targets
1904 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1905 for each of the ways of building the package, and a
1906 <tt>build</tt> target that does nothing. The
1907 <tt>binary</tt> target will have to build the
1908 package in each of the possible ways and make the
1909 binary package out of each.
1913 The <tt>build</tt> target must not do anything
1914 that might require root privilege.
1918 The <tt>build</tt> target may need to run the
1919 <tt>clean</tt> target first - see below.
1923 When a package has a configuration and build routine
1924 which takes a long time, or when the makefiles are
1925 poorly designed, or when <tt>build</tt> needs to
1926 run <tt>clean</tt> first, it is a good idea to
1927 <tt>touch build</tt> when the build process is
1928 complete. This will ensure that if <tt>debian/rules
1929 build</tt> is run again it will not rebuild the whole
1931 Another common way to do this is for <tt>build</tt>
1932 to depend on <prgn>build-stamp</prgn> and to do
1933 nothing else, and for the <prgn>build-stamp</prgn>
1934 target to do the building and to <tt>touch
1935 build-stamp</tt> on completion. This is
1936 especially useful if the build routine creates a
1937 file or directory called <tt>build</tt>; in such a
1938 case, <tt>build</tt> will need to be listed as
1939 a phony target (i.e., as a dependency of the
1940 <tt>.PHONY</tt> target). See the documentation of
1941 <prgn>make</prgn> for more information on phony
1947 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1948 <tt>binary-indep</tt>
1952 The <tt>binary</tt> target must be all that is
1953 necessary for the user to build the binary package(s)
1954 produced from this source package. All of these
1955 targets are required to be non-interactive. It is
1956 split into two parts: <prgn>binary-arch</prgn> builds
1957 the binary packages which are specific to a particular
1958 architecture, and <tt>binary-indep</tt> builds
1959 those which are not.
1962 <tt>binary</tt> may be (and commonly is) a target with
1963 no commands which simply depends on
1964 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1967 Both <tt>binary-*</tt> targets should depend on the
1968 <tt>build</tt> target, or on the appropriate
1969 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1970 provided, so that the package is built if it has not
1971 been already. It should then create the relevant
1972 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1973 make their control files and <prgn>dpkg-deb</prgn> to
1974 build them and place them in the parent of the top
1979 Both the <tt>binary-arch</tt> and
1980 <tt>binary-indep</tt> targets <em>must</em> exist.
1981 If one of them has nothing to do (which will always be
1982 the case if the source generates only a single binary
1983 package, whether architecture-dependent or not), it
1984 must still exist and must always succeed.
1988 The <tt>binary</tt> targets must be invoked as
1990 The <prgn>fakeroot</prgn> package often allows one
1991 to build a package correctly even without being
1997 <tag><tt>clean</tt></tag>
2000 This must undo any effects that the <tt>build</tt>
2001 and <tt>binary</tt> targets may have had, except
2002 that it should leave alone any output files created in
2003 the parent directory by a run of a <tt>binary</tt>
2004 target. This target must be non-interactive.
2008 If a <tt>build</tt> file is touched at the end of
2009 the <tt>build</tt> target, as suggested above, it
2010 should be removed as the first action that
2011 <tt>clean</tt> performs, so that running
2012 <tt>build</tt> again after an interrupted
2013 <tt>clean</tt> doesn't think that everything is
2018 The <tt>clean</tt> target may need to be
2019 invoked as root if <tt>binary</tt> has been
2020 invoked since the last <tt>clean</tt>, or if
2021 <tt>build</tt> has been invoked as root (since
2022 <tt>build</tt> may create directories, for
2027 <tag><tt>get-orig-source</tt> (optional)</tag>
2030 This target fetches the most recent version of the
2031 original source package from a canonical archive site
2032 (via FTP or WWW, for example), does any necessary
2033 rearrangement to turn it into the original source
2034 tar file format described below, and leaves it in the
2039 This target may be invoked in any directory, and
2040 should take care to clean up any temporary files it
2045 This target is optional, but providing it if
2046 possible is a good idea.
2052 The <tt>build</tt>, <tt>binary</tt> and
2053 <tt>clean</tt> targets must be invoked with the current
2054 directory being the package's top-level directory.
2059 Additional targets may exist in <file>debian/rules</file>,
2060 either as published or undocumented interfaces or for the
2061 package's internal use.
2065 The architectures we build on and build for are determined
2066 by <prgn>make</prgn> variables using the utility
2067 <qref id="pkg-dpkgarch"><prgn>dpkg-architecture</prgn></qref>.
2068 You can determine the
2069 Debian architecture and the GNU style architecture
2070 specification string for the build machine (the machine type
2071 we are building on) as well as for the host machine (the
2072 machine type we are building for). Here is a list of
2073 supported <prgn>make</prgn> variables:
2074 <list compact="compact">
2076 <tt>DEB_*_ARCH</tt> (the Debian architecture)
2079 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2080 specification string)
2083 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2084 <tt>DEB_*_GNU_TYPE</tt>)
2087 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2088 <tt>DEB_*_GNU_TYPE</tt>)
2090 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2091 the build machine or <tt>HOST</tt> for specification of the
2096 Backward compatibility can be provided in the rules file
2097 by setting the needed variables to suitable default
2098 values; please refer to the documentation of
2099 <prgn>dpkg-architecture</prgn> for details.
2103 It is important to understand that the <tt>DEB_*_ARCH</tt>
2104 string only determines which Debian architecture we are
2105 building on or for. It should not be used to get the CPU
2106 or system information; the GNU style variables should be
2111 <sect id="dpkgchangelog"><heading><file>debian/changelog</file>
2115 This file records the changes to the Debian-specific parts of the
2117 Though there is nothing stopping an author who is also
2118 the Debian maintainer from using it for all their
2119 changes, it will have to be renamed if the Debian and
2120 upstream maintainers become different people. In such a
2121 case, however, it might be better to maintain the
2122 package as a non-native package.
2127 It has a special format which allows the package building
2128 tools to discover which version of the package is being
2129 built and find out other release-specific information.
2133 That format is a series of entries like this:
2134 <example compact="compact">
2135 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
2137 <p>[optional blank line(s), stripped]</p>
2139 * <var>change details</var>
2140 <var>more change details</var>
2142 <p>[blank line(s), included in output of dpkg-parsechangelog]</p>
2144 * <var>even more change details</var>
2146 <p>[optional blank line(s), stripped]</p>
2148 -- <var>maintainer name</var> <<var>email
2149 address</var>><var>[two spaces]</var> <var>date</var>
2154 <var>package</var> and <var>version</var> are the source
2155 package name and version number.
2159 <var>distribution(s)</var> lists the distributions where
2160 this version should be installed when it is uploaded - it
2161 is copied to the <tt>Distribution</tt> field in the
2162 <file>.changes</file> file. See <ref id="f-Distribution">.
2166 <var>urgency</var> is the value for the <tt>Urgency</tt>
2167 field in the <file>.changes</file> file for the upload. It is
2168 not possible to specify an urgency containing commas; commas
2169 are used to separate
2170 <tt><var>keyword</var>=<var>value</var></tt> settings in the
2171 <prgn>dpkg</prgn> changelog format (though there is
2172 currently only one useful <var>keyword</var>,
2173 <tt>urgency</tt>).<footnote>
2174 Recognised urgency values are <tt>low</tt>,
2175 <tt>medium</tt>, <tt>high</tt> and <tt>emergency</tt>.
2176 They have an effect on how quickly a package will be
2177 considered for inclusion into the <tt>testing</tt>
2178 distribution, and give an indication of the importance
2179 of any fixes included in this upload.
2184 The change details may in fact be any series of lines
2185 starting with at least two spaces, but conventionally each
2186 change starts with an asterisk and a separating space and
2187 continuation lines are indented so as to bring them in
2188 line with the start of the text above. Blank lines may be
2189 used here to separate groups of changes, if desired.
2193 If this upload resolves bugs recorded in the Bug Tracking
2194 System (BTS), they may be automatically closed on the
2195 inclusion of this package into the Debian archive by
2196 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
2197 in the change details.<footnote>
2198 To be precise, the string should match the following
2199 Perl regular expression:
2201 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
2203 Then all of the bug numbers listed will be closed by the
2204 archive maintenance script (<prgn>katie</prgn>), or in
2205 the case of an NMU, marked as fixed.
2210 The maintainer name and email address used in the changelog
2211 should be the details of the person uploading <em>this</em>
2212 version. They are <em>not</em> necessarily those of the
2213 usual package maintainer. The information here will be
2214 copied to the <tt>Changed-By</tt> field in the
2215 <tt>.changes</tt> file, and then later used to send an
2216 acknowledgement when the upload has been installed.
2220 The <var>date</var> should be in RFC822 format<footnote>
2221 This is generated by the <prgn>822-date</prgn>
2223 </footnote>; it should include the time zone specified
2224 numerically, with the time zone name or abbreviation
2225 optionally present as a comment in parentheses.
2229 The first "title" line with the package name should start
2230 at the left hand margin; the "trailer" line with the
2231 maintainer and date details should be preceded by exactly
2232 one space. The maintainer details and the date must be
2233 separated by exactly two spaces.
2236 <sect1><heading>Defining alternative changelog formats</heading>
2239 It is possible to use a different format to the standard
2240 one, by providing a parser for the format you wish to
2244 A changelog parser must not interact with the user at
2250 <!-- FIXME: section pkg-srcsubstvars is the same as srcsubstvars -->
2252 <sect id="srcsubstvars"><heading><file>debian/substvars</file>
2253 and variable substitutions </heading>
2256 When <prgn>dpkg-gencontrol</prgn>,
2257 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2258 generate control files they perform variable substitutions
2259 on their output just before writing it. Variable
2260 substitutions have the form <tt>${<var>variable</var>}</tt>.
2261 The optional file <file>debian/substvars</file> contains
2262 variable substitutions to be used; variables can also be set
2263 directly from <file>debian/rules</file> using the <tt>-V</tt>
2264 option to the source packaging commands, and certain
2265 predefined variables are also available.
2269 The <file>debian/substvars</file> file is usually generated and
2270 modified dynamically by <file>debian/rules</file> targets, in
2271 which case it must be removed by the <tt>clean</tt> target.
2275 See <manref name="dpkg-source" section="1"> for full
2276 details about source variable substitutions, including the
2277 format of <file>debian/substvars</file>.</p>
2280 <sect id="debianfiles"><heading><file>debian/files</file>
2284 This file is not a permanent part of the source tree; it
2285 is used while building packages to record which files are
2286 being generated. <prgn>dpkg-genchanges</prgn> uses it
2287 when it generates a <file>.changes</file> file.
2291 It should not exist in a shipped source package, and so it
2292 (and any backup files or temporary files such as
2293 <file>files.new</file><footnote>
2294 <file>files.new</file> is used as a temporary file by
2295 <prgn>dpkg-gencontrol</prgn> and
2296 <prgn>dpkg-distaddfile</prgn> - they write a new
2297 version of <tt>files</tt> here before renaming it,
2298 to avoid leaving a corrupted copy if an error
2300 </footnote>) should be removed by the
2301 <tt>clean</tt> target. It may also be wise to
2302 ensure a fresh start by emptying or removing it at the
2303 start of the <tt>binary</tt> target.
2307 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2308 package, it adds an entry to <file>debian/files</file> for the
2309 <file>.deb</file> file that will be created when <tt>dpkg-deb
2310 --build</tt> is run for that binary package. So for most
2311 packages all that needs to be done with this file is to
2312 delete it in the <tt>clean</tt> target.
2316 If a package upload includes files besides the source
2317 package and any binary packages whose control files were
2318 made with <prgn>dpkg-gencontrol</prgn> then they should be
2319 placed in the parent of the package's top-level directory
2320 and <prgn>dpkg-distaddfile</prgn> should be called to add
2321 the file to the list in <file>debian/files</file>.</p>
2324 <sect id="restrictions"><heading>Restrictions on objects in source packages
2328 The source package may not contain any hard links<footnote>
2330 This is not currently detected when building source
2331 packages, but only when extracting
2335 Hard links may be permitted at some point in the
2336 future, but would require a fair amount of
2339 </footnote>, device special files, sockets or setuid or
2340 setgid files.<footnote>
2341 Setgid directories are allowed.
2346 <sect id="descriptions"><heading>Descriptions of packages - the
2347 <tt>Description</tt> field</heading>
2350 The "Description" control file field consists of two parts,
2351 the synopsis or the short description, and the long description.
2352 The field's format is as follows:
2356 Description: <single line synopsis>
2357 <extended description over several lines>
2361 The description is intended to describe the program to a user
2362 who has never met it before so that they know whether they
2363 want to install it. It should also give information about the
2364 significant dependencies and conflicts between this package
2365 and others, so that the user knows why these dependencies and
2366 conflicts have been declared.
2370 Put important information first, both in the synopsis and
2371 extended description. Sometimes only the first part of the
2372 synopsis or of the description will be displayed. You can
2373 assume that there will usually be a way to see the whole
2374 extended description.
2377 <sect1 id="synopsis"><heading>The single line synopsis</heading>
2380 The single line synopsis should be kept brief - certainly
2381 under 80 characters.
2385 Do not include the package name in the synopsis line. The
2386 display software knows how to display this already, and you
2387 do not need to state it. Remember that in many situations
2388 the user may only see the synopsis line - make it as
2389 informative as you can.
2394 <sect1 id="extendeddesc"><heading>The extended description</heading>
2397 Do not try to continue the single line synopsis into the
2398 extended description. This will not work correctly when
2399 the full description is displayed, and makes no sense
2400 where only the summary (the single line synopsis) is
2405 The extended description should describe what the package
2406 does and how it relates to the rest of the system (in terms
2407 of, for example, which subsystem it is which part of).
2411 The description field needs to make sense to anyone, even
2412 people who have no idea about any of the things the
2413 package deals with.<footnote>
2414 The blurb that comes with a program in its
2415 announcements and/or <prgn>README</prgn> files is
2416 rarely suitable for use in a description. It is
2417 usually aimed at people who are already in the
2418 community where the package is used.
2423 The lines in the extended description can have these formats:
2429 Those starting with a single space are part of a paragraph.
2430 Successive lines of this form will be word-wrapped when
2431 displayed. The leading space will usually be stripped off.
2435 Those starting with two or more spaces. These will be
2436 displayed verbatim. If the display cannot be panned
2437 horizontally, the displaying program will linewrap them "hard"
2438 (i.e., without taking account of word breaks). If it can they
2439 will be allowed to trail off to the right. None, one or two
2440 initial spaces may be deleted, but the number of spaces
2441 deleted from each line will be the same (so that you can have
2442 indenting work correctly, for example).
2446 Those containing a single space followed by a single full stop
2447 character. These are rendered as blank lines. This is the
2448 <em>only</em> way to get a blank line<footnote>
2449 Completely empty lines will not be rendered as blank lines.
2450 Instead, they will cause the parser to think you're starting
2451 a whole new record in the control file, and will therefore
2452 likely abort with an error.
2457 Those containing a space, a full stop and some more characters.
2458 These are for future expansion. Do not use them.
2464 Do not use tab characters. Their effect is not predictable.
2474 <chapt id="maintainerscripts"><heading>Package maintainer scripts
2475 and installation procedure
2478 <sect><heading>Introduction to package maintainer scripts
2482 It is possible to supply scripts as part of a package which
2483 the package management system will run for you when your
2484 package is installed, upgraded or removed.
2488 These scripts are the files <prgn>preinst</prgn>,
2489 <prgn>postinst</prgn>, <prgn>prerm</prgn> and <prgn>postrm</prgn> in the
2490 control area of the package. They must be proper executable
2491 files; if they are scripts (which is recommended), they must
2492 start with the usual <tt>#!</tt> convention. They should be
2493 readable and executable by anyone, and not world-writable.
2497 The package management system looks at the exit status from
2498 these scripts. It is important that they exit with a
2499 non-zero status if there is an error, so that the package
2500 management system can stop its processing. For shell
2501 scripts this means that you <em>almost always</em> need to
2502 use <tt>set -e</tt> (this is usually true when writing shell
2503 scripts, in fact). It is also important, of course, that
2504 they don't exit with a non-zero status if everything went
2509 When a package is upgraded a combination of the scripts from
2510 the old and new packages is called during the upgrade
2511 procedure. If your scripts are going to be at all
2512 complicated you need to be aware of this, and may need to
2513 check the arguments to your scripts.
2517 Broadly speaking the <prgn>preinst</prgn> is called before
2518 (a particular version of) a package is installed, and the
2519 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
2520 before (a version of) a package is removed and the
2521 <prgn>postrm</prgn> afterwards.
2525 Programs called from maintainer scripts should not normally
2526 have a path prepended to them. Before installation is
2527 started, the package management system checks to see if the
2528 programs <prgn>ldconfig</prgn>,
2529 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
2530 and <prgn>update-rc.d</prgn> can be found via the
2531 <tt>PATH</tt> environment variable. Those programs, and any
2532 other program that one would expect to be on the
2533 <tt>PATH</tt>, should thus be invoked without an absolute
2534 pathname. Maintainer scripts should also not reset the
2535 <tt>PATH</tt>, though they might choose to modify it by
2536 prepending or appending package-specific directories. These
2537 considerations really apply to all shell scripts.</p>
2541 <heading>Maintainer scripts Idempotency</heading>
2544 It is necessary for the error recovery procedures that the
2545 scripts be idempotent. This means that if it is run
2546 successfully, and then it is called again, it doesn't bomb
2547 out or cause any harm, but just ensures that everything is
2548 the way it ought to be. If the first call failed, or
2549 aborted half way through for some reason, the second call
2550 should merely do the things that were left undone the first
2551 time, if any, and exit with a success status if everything
2553 This is so that if an error occurs, the user interrupts
2554 <prgn>dpkg</prgn> or some other unforeseen circumstance
2555 happens you don't leave the user with a badly-broken
2556 package when <prgn>dpkg</prgn> attempts to repeat the
2563 <heading>Controlling terminal for maintainer scripts</heading>
2566 The maintainer scripts are guaranteed to run with a
2567 controlling terminal and can interact with the user.
2568 If they need to prompt for passwords, do full-screen
2569 interaction or something similar you should do these
2570 things to and from <file>/dev/tty</file>, since
2571 <prgn>dpkg</prgn> will at some point redirect scripts'
2572 standard input and output so that it can log the
2573 installation process. Likewise, because these scripts
2574 may be executed with standard output redirected into a
2575 pipe for logging purposes, Perl scripts should set
2576 unbuffered output by setting <tt>$|=1</tt> so that the
2577 output is printed immediately rather than being
2582 Each script should return a zero exit status for
2583 success, or a nonzero one for failure.
2587 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
2592 <list compact="compact">
2594 <var>new-preinst</var> <tt>install</tt>
2597 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
2600 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
2603 <var>old-preinst</var> <tt>abort-upgrade</tt>
2604 <var>new-version</var>
2609 <list compact="compact">
2611 <var>postinst</var> <tt>configure</tt>
2612 <var>most-recently-configured-version</var>
2615 <var>old-postinst</var> <tt>abort-upgrade</tt>
2616 <var>new-version</var>
2619 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
2620 <tt>in-favour</tt> <var>package</var>
2621 <var>new-version</var>
2624 <var>deconfigured's-postinst</var>
2625 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
2626 <var>failed-install-package</var> <var>version</var>
2627 <tt>removing</tt> <var>conflicting-package</var>
2633 <list compact="compact">
2635 <var>prerm</var> <tt>remove</tt>
2638 <var>old-prerm</var> <tt>upgrade</tt>
2639 <var>new-version</var>
2642 <var>new-prerm</var> <tt>failed-upgrade</tt>
2643 <var>old-version</var>
2646 <var>conflictor's-prerm</var> <tt>remove</tt>
2647 <tt>in-favour</tt> <var>package</var>
2648 <var>new-version</var>
2651 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
2652 <tt>in-favour</tt> <var>package-being-installed</var>
2653 <var>version</var> <tt>removing</tt>
2654 <var>conflicting-package</var>
2660 <list compact="compact">
2662 <var>postrm</var> <tt>remove</tt>
2665 <var>postrm</var> <tt>purge</tt>
2668 <var>old-postrm</var> <tt>upgrade</tt>
2669 <var>new-version</var>
2672 <var>new-postrm</var> <tt>failed-upgrade</tt>
2673 <var>old-version</var>
2676 <var>new-postrm</var> <tt>abort-install</tt>
2679 <var>new-postrm</var> <tt>abort-install</tt>
2680 <var>old-version</var>
2683 <var>new-postrm</var> <tt>abort-upgrade</tt>
2684 <var>old-version</var>
2687 <var>disappearer's-postrm</var> <tt>disappear</tt>
2688 <var>overwriter</var>
2689 <var>overwriter-version</var>
2695 <sect id="unpackphase">
2696 <heading>Details of unpack phase of installation or upgrade</heading>
2699 The procedure on installation/upgrade/overwrite/disappear
2700 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
2701 stage of <tt>dpkg --install</tt>) is as follows. In each
2702 case, if a major error occurs (unless listed below) the
2703 actions are, in general, run backwards - this means that the
2704 maintainer scripts are run with different arguments in
2705 reverse order. These are the "error unwind" calls listed
2712 If a version of the package is already installed, call
2713 <example compact="compact">
2714 <var>old-prerm</var> upgrade <var>new-version</var>
2718 If the script runs but exits with a non-zero
2719 exit status, <prgn>dpkg</prgn> will attempt:
2720 <example compact="compact">
2721 <var>new-prerm</var> failed-upgrade <var>old-version</var>
2723 Error unwind, for both the above cases:
2724 <example compact="compact">
2725 <var>old-postinst</var> abort-upgrade <var>new-version</var>
2732 If a "conflicting" package is being removed at the same time:
2735 If any packages depended on that conflicting
2736 package and <tt>--auto-deconfigure</tt> is
2737 specified, call, for each such package:
2738 <example compact="compact">
2739 <var>deconfigured's-prerm</var> deconfigure \
2740 in-favour <var>package-being-installed</var> <var>version</var> \
2741 removing <var>conflicting-package</var> <var>version</var>
2744 <example compact="compact">
2745 <var>deconfigured's-postinst</var> abort-deconfigure \
2746 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
2747 removing <var>conflicting-package</var> <var>version</var>
2749 The deconfigured packages are marked as
2750 requiring configuration, so that if
2751 <tt>--install</tt> is used they will be
2752 configured again if possible.
2755 To prepare for removal of the conflicting package, call:
2756 <example compact="compact">
2757 <var>conflictor's-prerm</var> remove \
2758 in-favour <var>package</var> <var>new-version</var>
2761 <example compact="compact">
2762 <var>conflictor's-postinst</var> abort-remove \
2763 in-favour <var>package</var> <var>new-version</var>
2772 If the package is being upgraded, call:
2773 <example compact="compact">
2774 <var>new-preinst</var> upgrade <var>old-version</var>
2778 Otherwise, if the package had some configuration
2779 files from a previous version installed (i.e., it
2780 is in the "configuration files only" state):
2781 <example compact="compact">
2782 <var>new-preinst</var> install <var>old-version</var>
2786 Otherwise (i.e., the package was completely purged):
2787 <example compact="compact">
2788 <var>new-preinst</var> install
2790 Error unwind actions, respectively:
2791 <example compact="compact">
2792 <var>new-postrm</var> abort-upgrade <var>old-version</var>
2793 <var>new-postrm</var> abort-install <var>old-version</var>
2794 <var>new-postrm</var> abort-install
2802 The new package's files are unpacked, overwriting any
2803 that may be on the system already, for example any
2804 from the old version of the same package or from
2805 another package. Backups of the old files are kept
2806 temporarily, and if anything goes wrong the package
2807 management system will attempt to put them back as
2808 part of the error unwind.
2812 It is an error for a package to contains files which
2813 are on the system in another package, unless
2814 <tt>Replaces</tt> is used (see <ref id="replaces">).
2816 The following paragraph is not currently the case:
2817 Currently the <tt>- - force-overwrite</tt> flag is
2818 enabled, downgrading it to a warning, but this may not
2824 It is a more serious error for a package to contain a
2825 plain file or other kind of non-directory where another
2826 package has a directory (again, unless
2827 <tt>Replaces</tt> is used). This error can be
2828 overridden if desired using
2829 <tt>--force-overwrite-dir</tt>, but this is not
2834 Packages which overwrite each other's files produce
2835 behavior which, though deterministic, is hard for the
2836 system administrator to understand. It can easily
2837 lead to "missing" programs if, for example, a package
2838 is installed which overwrites a file from another
2839 package, and is then removed again.<footnote>
2840 Part of the problem is due to what is arguably a
2841 bug in <prgn>dpkg</prgn>.
2846 A directory will never be replaced by a symbolic link
2847 to a directory or vice versa; instead, the existing
2848 state (symlink or not) will be left alone and
2849 <prgn>dpkg</prgn> will follow the symlink if there is
2858 If the package is being upgraded, call
2859 <example compact="compact">
2860 <var>old-postrm</var> upgrade <var>new-version</var>
2864 If this fails, <prgn>dpkg</prgn> will attempt:
2865 <example compact="compact">
2866 <var>new-postrm</var> failed-upgrade <var>old-version</var>
2868 Error unwind, for both cases:
2869 <example compact="compact">
2870 <var>old-preinst</var> abort-upgrade <var>new-version</var>
2877 This is the point of no return - if
2878 <prgn>dpkg</prgn> gets this far, it won't back off
2879 past this point if an error occurs. This will
2880 leave the package in a fairly bad state, which
2881 will require a successful re-installation to clear
2882 up, but it's when <prgn>dpkg</prgn> starts doing
2883 things that are irreversible.
2888 Any files which were in the old version of the package
2889 but not in the new are removed.
2893 The new file list replaces the old.
2897 The new maintainer scripts replace the old.
2901 Any packages all of whose files have been overwritten
2902 during the installation, and which aren't required for
2903 dependencies, are considered to have been removed.
2904 For each such package
2907 <prgn>dpkg</prgn> calls:
2908 <example compact="compact">
2909 <var>disappearer's-postrm</var> disappear \
2910 <var>overwriter</var> <var>overwriter-version</var>
2914 The package's maintainer scripts are removed.
2917 It is noted in the status database as being in a
2918 sane state, namely not installed (any conffiles
2919 it may have are ignored, rather than being
2920 removed by <prgn>dpkg</prgn>). Note that
2921 disappearing packages do not have their prerm
2922 called, because <prgn>dpkg</prgn> doesn't know
2923 in advance that the package is going to
2930 Any files in the package we're unpacking that are also
2931 listed in the file lists of other packages are removed
2932 from those lists. (This will lobotomize the file list
2933 of the "conflicting" package if there is one.)
2937 The backup files made during installation, above, are
2943 The new package's status is now sane, and recorded as
2948 Here is another point of no return - if the
2949 conflicting package's removal fails we do not unwind
2950 the rest of the installation; the conflicting package
2951 is left in a half-removed limbo.
2956 If there was a conflicting package we go and do the
2957 removal actions (described below), starting with the
2958 removal of the conflicting package's files (any that
2959 are also in the package being installed have already
2960 been removed from the conflicting package's file list,
2961 and so do not get removed now).
2967 <sect id="configdetails"><heading>Details of configuration</heading>
2970 When we configure a package (this happens with <tt>dpkg
2971 --install</tt> and <tt>dpkg --configure</tt>), we first
2972 update any <tt>conffile</tt>s and then call:
2973 <example compact="compact">
2974 <var>postinst</var> configure <var>most-recently-configured-version</var>
2979 No attempt is made to unwind after errors during
2984 If there is no most recently configured version
2985 <prgn>dpkg</prgn> will pass a null argument; older versions
2986 of dpkg may pass <tt><unknown></tt> (including the
2987 angle brackets) in this case. Even older ones do not pass a
2988 second argument at all, under any circumstances.
2992 <sect id="removedetails"><heading>Details of removal and/or
2993 configuration purging</heading>
2998 <example compact="compact">
2999 <var>prerm</var> remove
3003 The package's files are removed (except <tt>conffile</tt>s).
3006 <example compact="compact">
3007 <var>postrm</var> remove
3012 All the maintainer scripts except the <prgn>postrm</prgn>
3017 If we aren't purging the package we stop here. Note
3018 that packages which have no <prgn>postrm</prgn> and no
3019 <tt>conffile</tt>s are automatically purged when
3020 removed, as there is no difference except for the
3021 <prgn>dpkg</prgn> status.
3025 The <tt>conffile</tt>s and any backup files
3026 (<tt>~</tt>-files, <tt>#*#</tt> files,
3027 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
3031 <example compact="compact">
3032 <var>postrm</var> purge
3036 The package's file list is removed.
3040 No attempt is made to unwind after errors during
3047 <chapt id="relationships">
3048 <heading>Declaring relationships between packages</heading>
3050 <sect id="depsyntax">
3051 <heading>Syntax of relationship fields</heading>
3054 These fields all have a uniform syntax. They are a list of
3055 package names separated by commas.
3059 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3060 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3061 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3062 control file fields of the package, which declare
3063 dependencies on other packages, the package names listed may
3064 also include lists of alternative package names, separated
3065 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
3066 if any one of the alternative packages is installed, that
3067 part of the dependency is considered to be satisfied.
3071 All of the fields except for <tt>Provides</tt> may restrict
3072 their applicability to particular versions of each named
3073 package. This is done in parentheses after each individual
3074 package name; the parentheses should contain a relation from
3075 the list below followed by a version number, in the format
3076 described in <ref id="versions">.
3080 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3081 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3082 strictly earlier, earlier or equal, exactly equal, later or
3083 equal and strictly later, respectively. The deprecated
3084 forms <tt><</tt> and <tt>></tt> were used to mean
3085 earlier/later or equal, rather than strictly earlier/later,
3086 so they should not appear in new packages (though
3087 <prgn>dpkg</prgn> still supports them).
3091 Whitespace may appear at any point in the version
3092 specification subject to the rules in <ref
3093 id="controlsyntax">, and must appear where it's necessary to
3094 disambiguate; it is not otherwise significant. For
3095 consistency and in case of future changes to
3096 <prgn>dpkg</prgn> it is recommended that a single space be
3097 used after a version relationship and before a version
3098 number; it is also conventional to put a single space after
3099 each comma, on either side of each vertical bar, and before
3100 each open parenthesis.
3104 For example, a list of dependencies might appear as:
3105 <example compact="compact">
3108 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
3113 All fields that specify build-time relationships
3114 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3115 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3116 may be restricted to a certain set of architectures. This
3117 is indicated in brackets after each individual package name and
3118 the optional version specification. The brackets enclose a
3119 list of Debian architecture names separated by whitespace.
3120 Exclamation marks may be prepended to each of the names.
3121 (It is not permitted for some names to be prepended with
3122 exclamation marks and others not.) If the current Debian
3123 host architecture is not in this list and there are no
3124 exclamation marks in the list, or it is in the list with a
3125 prepended exclamation mark, the package name and the
3126 associated version specification are ignored completely for
3127 the purposes of defining the relationships.
3132 <example compact="compact">
3134 Build-Depends-Indep: texinfo
3135 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3136 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3141 Note that the binary package relationship fields such as
3142 <tt>Depends</tt> appear in one of the binary package
3143 sections of the control file, whereas the build-time
3144 relationships such as <tt>Build-Depends</tt> appear in the
3145 source package section of the control file (which is the
3151 <heading>Binary Dependencies - <tt>Depends</tt>,
3152 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3153 <tt>Pre-Depends</tt>
3157 Packages can declare in their control file that they have
3158 certain relationships to other packages - for example, that
3159 they may not be installed at the same time as certain other
3160 packages, and/or that they depend on the presence of others.
3164 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
3165 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt> and
3166 <tt>Conflicts</tt> control file fields.
3170 These six fields are used to declare a dependency
3171 relationship by one package on another. Except for
3172 <tt>Enhances</tt>, they appear in the depending (binary)
3173 package's control file. (<tt>Enhances</tt> appears in the
3174 recommending package's control file.)
3178 A <tt>Depends</tt> field takes effect <em>only</em> when a
3179 package is to be configured. It does not prevent a package
3180 being on the system in an unconfigured state while its
3181 dependencies are unsatisfied, and it is possible to replace
3182 a package whose dependencies are satisfied and which is
3183 properly installed with a different version whose
3184 dependencies are not and cannot be satisfied; when this is
3185 done the depending package will be left unconfigured (since
3186 attempts to configure it will give errors) and will not
3187 function properly. If it is necessary, a
3188 <tt>Pre-Depends</tt> field can be used, which has a partial
3189 effect even when a package is being unpacked, as explained
3190 in detail below. (The other three dependency fields,
3191 <tt>Recommends</tt>, <tt>Suggests</tt> and
3192 <tt>Enhances</tt>, are only used by the various front-ends
3193 to <prgn>dpkg</prgn> such as <prgn>dselect</prgn>.)
3197 For this reason packages in an installation run are usually
3198 all unpacked first and all configured later; this gives
3199 later versions of packages with dependencies on later
3200 versions of other packages the opportunity to have their
3201 dependencies satisfied.
3205 The <tt>Depends</tt> field thus allows package maintainers
3206 to impose an order in which packages should be configured.
3210 The meaning of the five dependency fields is as follows:
3212 <tag><tt>Depends</tt></tag>
3215 This declares an absolute dependency. A package will
3216 not be configured unless all of the packages listed in
3217 its <tt>Depends</tt> field have been correctly
3222 The <tt>Depends</tt> field should be used if the
3223 depended-on package is required for the depending
3224 package to provide a significant amount of
3229 The <tt>Depends</tt> field should also be used if the
3230 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
3231 <prgn>postrm</prgn> scripts require the package to be
3232 present in order to run. Note, however, that the
3233 <prgn>postrm</prgn> cannot rely on any non-essential
3234 packages to be present during the <tt>purge</tt>
3238 <tag><tt>Recommends</tt></tag>
3241 This declares a strong, but not absolute, dependency.
3245 The <tt>Recommends</tt> field should list packages
3246 that would be found together with this one in all but
3247 unusual installations.
3251 <tag><tt>Suggests</tt></tag>
3253 This is used to declare that one package may be more
3254 useful with one or more others. Using this field
3255 tells the packaging system and the user that the
3256 listed packages are related to this one and can
3257 perhaps enhance its usefulness, but that installing
3258 this one without them is perfectly reasonable.
3261 <tag><tt>Enhances</tt></tag>
3263 This field is similar to Suggests but works in the
3264 opposite direction. It is used to declare that a
3265 package can enhance the functionality of another
3269 <tag><tt>Pre-Depends</tt></tag>
3272 This field is like <tt>Depends</tt>, except that it
3273 also forces <prgn>dpkg</prgn> to complete installation
3274 of the packages named before even starting the
3275 installation of the package which declares the
3276 pre-dependency, as follows:
3280 When a package declaring a pre-dependency is about to
3281 be <em>unpacked</em> the pre-dependency can be
3282 satisfied if the depended-on package is either fully
3283 configured, <em>or even if</em> the depended-on
3284 package(s) are only unpacked or half-configured,
3285 provided that they have been configured correctly at
3286 some point in the past (and not removed or partially
3287 removed since). In this case, both the
3288 previously-configured and currently unpacked or
3289 half-configured versions must satisfy any version
3290 clause in the <tt>Pre-Depends</tt> field.
3294 When the package declaring a pre-dependency is about
3295 to be <em>configured</em>, the pre-dependency will be
3296 treated as a normal <tt>Depends</tt>, that is, it will
3297 be considered satisfied only if the depended-on
3298 package has been correctly configured.
3302 <tt>Pre-Depends</tt> should be used sparingly,
3303 preferably only by packages whose premature upgrade or
3304 installation would hamper the ability of the system to
3305 continue with any upgrade that might be in progress.
3309 <tt>Pre-Depends</tt> are also required if the
3310 <prgn>preinst</prgn> script depends on the named
3311 package. It is best to avoid this situation if
3319 When selecting which level of dependency to use you should
3320 consider how important the depended-on package is to the
3321 functionality of the one declaring the dependency. Some
3322 packages are composed of components of varying degrees of
3323 importance. Such a package should list using
3324 <tt>Depends</tt> the package(s) which are required by the
3325 more important components. The other components'
3326 requirements may be mentioned as Suggestions or
3327 Recommendations, as appropriate to the components' relative
3332 <sect id="conflicts">
3333 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
3336 When one binary package declares a conflict with another
3337 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
3338 refuse to allow them to be installed on the system at the
3343 If one package is to be installed, the other must be removed
3344 first - if the package being installed is marked as
3345 replacing (see <ref id="replaces">) the one on the system,
3346 or the one on the system is marked as deselected, or both
3347 packages are marked <tt>Essential</tt>, then
3348 <prgn>dpkg</prgn> will automatically remove the package
3349 which is causing the conflict, otherwise it will halt the
3350 installation of the new package with an error. This
3351 mechanism is specifically designed to produce an error when
3352 the installed package is <tt>Essential</tt>, but the new
3357 A package will not cause a conflict merely because its
3358 configuration files are still installed; it must be at least
3363 A special exception is made for packages which declare a
3364 conflict with their own package name, or with a virtual
3365 package which they provide (see below): this does not
3366 prevent their installation, and allows a package to conflict
3367 with others providing a replacement for it. You use this
3368 feature when you want the package in question to be the only
3369 package providing some feature.
3373 A <tt>Conflicts</tt> entry should almost never have an
3374 "earlier than" version clause. This would prevent
3375 <prgn>dpkg</prgn> from upgrading or installing the package
3376 which declared such a conflict until the upgrade or removal
3377 of the conflicted-with package had been completed.
3381 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
3385 As well as the names of actual ("concrete") packages, the
3386 package relationship fields <tt>Depends</tt>,
3387 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3388 <tt>Pre-Depends</tt>, <tt>Conflicts</tt>,
3389 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3390 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
3391 may mention "virtual packages".
3395 A <em>virtual package</em> is one which appears in the
3396 <tt>Provides</tt> control file field of another package.
3397 The effect is as if the package(s) which provide a
3398 particular virtual package name had been listed by name
3399 everywhere the virtual package name appears. (See also <ref
3404 If there are both concrete and virtual packages of the same
3405 name, then the dependency may be satisfied (or the conflict
3406 caused) by either the concrete package with the name in
3407 question or any other concrete package which provides the
3408 virtual package with the name in question. This is so that,
3409 for example, supposing we have
3410 <example compact="compact">
3414 and someone else releases an enhanced version of the
3415 <tt>bar</tt> package (for example, a non-US variant), they
3417 <example compact="compact">
3421 and the <tt>bar-plus</tt> package will now also satisfy the
3422 dependency for the <tt>foo</tt> package.
3426 If a dependency or a conflict has a version number attached
3427 then only real packages will be considered to see whether
3428 the relationship is satisfied (or the prohibition violated,
3429 for a conflict) - it is assumed that a real package which
3430 provides the virtual package is not of the "right" version.
3431 So, a <tt>Provides</tt> field may not contain version
3432 numbers, and the version number of the concrete package
3433 which provides a particular virtual package will not be
3434 looked at when considering a dependency on or conflict with
3435 the virtual package name.
3439 It is likely that the ability will be added in a future
3440 release of <prgn>dpkg</prgn> to specify a version number for
3441 each virtual package it provides. This feature is not yet
3442 present, however, and is expected to be used only
3447 If you want to specify which of a set of real packages
3448 should be the default to satisfy a particular dependency on
3449 a virtual package, you should list the real package as an
3450 alternative before the virtual one.
3455 <sect id="replaces"><heading>Overwriting files and replacing
3456 packages - <tt>Replaces</tt></heading>
3459 Packages can declare in their control file that they should
3460 overwrite files in certain other packages, or completely
3461 replace other packages. The <tt>Replaces</tt> control file
3462 field has these two distinct purposes.
3465 <sect1><heading>Overwriting files in other packages</heading>
3468 Firstly, as mentioned before, it is usually an error for a
3469 package to contain files which are on the system in
3474 However, if the overwriting package declares that it
3475 <tt>Replaces</tt> the one containing the file being
3476 overwritten, then <prgn>dpkg</prgn> will replace the file
3477 from the old package with that from the new. The file
3478 will no longer be listed as "owned" by the old package.
3482 If a package is completely replaced in this way, so that
3483 <prgn>dpkg</prgn> does not know of any files it still
3484 contains, it is considered to have "disappeared". It will
3485 be marked as not wanted on the system (selected for
3486 removal) and not installed. Any <tt>conffile</tt>s
3487 details noted for the package will be ignored, as they
3488 will have been taken over by the overwriting package. The
3489 package's <prgn>postrm</prgn> script will be run with a
3490 special argument to allow the package to do any final
3491 cleanup required. See <ref id="mscriptsinstact">.
3495 If an installed package, <tt>foo</tt> say, declares that
3496 it replaces another, <tt>bar</tt>, and an attempt is made
3497 to install <tt>bar</tt>, <prgn>dpkg</prgn> will discard
3498 files in the <tt>bar</tt> package which would overwrite
3499 those already present in <tt>foo</tt>. This is so that
3500 you can install an older version of a package without
3505 For this usage of <tt>Replaces</tt>, virtual packages (see
3506 <ref id="virtual">) are not considered when looking at a
3507 <tt>Replaces</tt> field - the packages declared as being
3508 replaced must be mentioned by their real names.
3512 Furthermore, this usage of <tt>Replaces</tt> only takes
3513 effect when both packages are at least partially on the
3514 system at once, so that it can only happen if they do not
3515 conflict or if the conflict has been overridden.
3520 <sect1><heading>Replacing whole packages, forcing their
3524 Secondly, <tt>Replaces</tt> allows the packaging system to
3525 resolve which package should be removed when there is a
3526 conflict - see <ref id="conflicts">. This usage only
3527 takes effect when the two packages <em>do</em> conflict,
3528 so that the two usages of this field do not interfere with
3533 In this situation, the package declared as being replaced
3534 can be a virtual package, so for example, all mail
3535 transport agents (MTAs) would have the following fields in
3536 their control files:
3537 <example compact="compact">
3538 Provides: mail-transport-agent
3539 Conflicts: mail-transport-agent
3540 Replaces: mail-transport-agent
3542 ensuring that only one MTA can be installed at any one
3547 <sect><heading>Relationships between source and binary packages -
3548 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3549 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
3553 Source packages that require certain binary packages to be
3554 installed or absent at the time of building the package
3555 can declare relationships to those binary packages.
3559 This is done using the <tt>Build-Depends</tt>,
3560 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
3561 <tt>Build-Conflicts-Indep</tt> control file fields.
3565 Build-dependencies on "build-essential" binary packages can be
3566 omitted. Please see <ref id="pkg-relations"> for more information.
3570 The dependencies and conflicts they define must be satisfied
3571 (as defined earlier for binary packages) in order to invoke
3572 the targets in <tt>debian/rules</tt>, as follows:<footnote>
3574 If you make "build-arch" or "binary-arch", you need
3575 Build-Depends. If you make "build-indep" or
3576 "binary-indep", you need Build-Depends and
3577 Build-Depends-Indep. If you make "build" or "binary",
3581 There is no Build-Depends-Arch; the autobuilders will
3582 only need the Build-Depends if they know how to build
3583 only build-arch and binary-arch. Anyone building the
3584 build-indep/binary-indep targets is basically assumed to
3585 be building the whole package and so installs all build
3589 The purpose of the original split, I recall, was so that
3590 the autobuilders wouldn't need to install extra packages
3591 needed only for the binary-indep targets. But without a
3592 build-arch/build-indep split, this didn't work, since
3593 most of the work is done in the build target, not in the
3599 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
3601 The <tt>Build-Depends</tt> and
3602 <tt>Build-Conflicts</tt> fields must be satisfied when
3603 any of the following targets is invoked:
3604 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
3605 <tt>binary-arch</tt>, <tt>build-arch</tt>,
3606 <tt>build-indep</tt> and <tt>binary-indep</tt>.
3608 <tag><tt>Build-Depends-Indep</tt>,
3609 <tt>Build-Conflicts-Indep</tt></tag>
3611 The <tt>Build-Depends-Indep</tt> and
3612 <tt>Build-Conflicts-Indep</tt> fields must be
3613 satisfied when any of the following targets is
3614 invoked: <tt>build</tt>, <tt>clean</tt>,
3615 <tt>build-indep</tt>, <tt>binary</tt> and
3616 <tt>binary-indep</tt>.
3627 <chapt id="conffiles">
3628 <heading>Configuration file handling</heading>
3631 This chapter has been superseded by <ref id="config-files">.
3636 <chapt id="sharedlibs"><heading>Shared libraries</heading>
3639 Packages containing shared libraries must be constructed with
3640 a little care to make sure that the shared library is always
3641 available. This is especially important for packages whose
3642 shared libraries are vitally important, such as the C library
3643 (currently <tt>libc6</tt>).
3647 Packages involving shared libraries should be split up into
3648 several binary packages. This section mostly deals with how
3649 this separation is to be accomplished; rules for files within
3650 the shared library packages are in <ref id="libraries"> instead.
3653 <sect id="sharedlibs-runtime">
3654 <heading>Run-time shared libraries</heading>
3657 The run-time shared library needs to be placed in a package called
3658 <package><var>libraryname</var><var>soversion</var></package>, where
3659 <file><var>soversion</var></file> is the version number in the
3660 soname of the shared library<footnote>
3661 The soname is the shared object name: it's the thing
3662 that has to match exactly between building an executable
3663 and running it for the dynamic linker to be able run the
3664 program. For example, if the soname of the library is
3665 <file>libfoo.so.6</file>, the library package would be
3666 called <file>libfoo6</file>.
3668 Alternatively, if it would be confusing to directly append
3669 <var>soversion</var> to <var>libraryname</var> (e.g. because
3670 <var>libraryname</var> itself ends in a number), you may use
3671 <package><var>libraryname</var>-<var>soversion</var></package> and
3672 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
3677 If you have several shared libraries built from the same
3678 source tree you may lump them all together into a single
3679 shared library package, provided that you change all of
3680 their sonames at once (so that you don't get filename
3681 clashes if you try to install different versions of the
3682 combined shared libraries package).
3686 The package should install the shared libraries under
3687 their normal names. For example, the <package>libgdbmg1</package>
3688 package should install <file>libgdbm.so.1.7.3</file> as
3689 <file>/usr/lib/libgdbm.so.1.7.3</file>. The files should not be
3690 renamed or re-linked by any <prgn>prerm</prgn> or
3691 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
3692 of renaming things safely without affecting running programs,
3693 and attempts to interfere with this are likely to lead to
3698 Shared libraries should not be installed executable, since
3699 the dynamic linker does not require this and trying to
3700 execute a shared library usually results in a core dump.
3704 The run-time library package should include the symbolic link that
3705 <prgn>ldconfig</prgn> would create for the shared libraries.
3706 For example, the <package>libgdbmg1</package> package should include
3707 a symbolic link from <file>/usr/lib/libgdbm.so.1</file> to
3708 <file>libgdbm.so.1.7.3</file>. This is needed so that the dynamic
3709 linker (for example <prgn>ld.so</prgn> or
3710 <prgn>ld-linux.so.*</prgn>) can find the library between the
3711 time that <prgn>dpkg</prgn> installs it and the time that
3712 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
3714 The package management system requires the library to be
3715 placed before the symbolic link pointing to it in the
3716 <file>.deb</file> file. This is so that when
3717 <prgn>dpkg</prgn> comes to install the symlink
3718 (overwriting the previous symlink pointing at an older
3719 version of the library), the new shared library is already
3720 in place. In the past, this was achieved by creating the
3721 library in the temporary packaging directory before
3722 creating the symlink. Unfortunately, this was not always
3723 effective, since the building of the tar file in the
3724 <file>.deb</file> depended on the behavior of the underlying
3725 file system. Some file systems (such as reiserfs) reorder
3726 the files so that the order of creation is forgotten.
3727 Since version 1.7.0, <prgn>dpkg</prgn>
3728 reorders the files itself as necessary when building a
3729 package. Thus it is no longer important to concern
3730 oneself with the order of file creation.
3734 <sect1 id="ldconfig">
3735 <heading><tt>ldconfig</tt></heading>
3738 Any package installing shared libraries in one of the default
3739 library directories of the dynamic linker (which are currently
3740 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
3741 listed in <file>/etc/ld.so.conf</file><footnote>
3743 <list compact="compact">
3744 <item>/usr/X11R6/lib/Xaw3d</item>
3745 <item>/usr/local/lib</item>
3746 <item>/usr/lib/libc5-compat</item>
3747 <item>/lib/libc5-compat</item>
3748 <item>/usr/X11R6/lib</item>
3751 must use <prgn>ldconfig</prgn> to update the shared library
3756 The package must call <prgn>ldconfig</prgn> in the
3757 <prgn>postinst</prgn> script if the first argument is
3758 <tt>configure</tt>; the <prgn>postinst</prgn> script may
3759 optionally invoke <prgn>ldconfig</prgn> at other times. The
3760 package should call <prgn>ldconfig</prgn> in the
3761 <prgn>postrm</prgn> script if the first argument is
3762 <tt>remove</tt>. The maintainer scripts must not invoke
3763 <prgn>ldconfig</prgn> under any circumstances other than those
3764 described in this paragraph.<footnote>
3766 During install or upgrade, the preinst is called before
3767 the new files are installed, so calling "ldconfig" is
3768 pointless. The preinst of an existing package can also be
3769 called if an upgrade fails. However, this happens during
3770 the critical time when a shared libs may exist on-disk
3771 under a temporary name. Thus, it is dangerous and
3772 forbidden by current policy to call "ldconfig" at this
3777 When a package is installed or upgraded, "postinst
3778 configure" runs after the new files are safely on-disk.
3779 Since it is perfectly safe to invoke ldconfig
3780 unconditionally in a postinst, it is OK for a package to
3781 simply put ldconfig in its postinst without checking the
3782 argument. The postinst can also be called to recover from
3783 a failed upgrade. This happens before any new files are
3784 unpacked, so there is no reason to call "ldconfig" at this
3789 For a package that is being removed, prerm is
3790 called with all the files intact, so calling ldconfig is
3791 useless. The other calls to "prerm" happen in the case of
3792 upgrade at a time when all the files of the old package
3793 are on-disk, so again calling "ldconfig" is pointless.
3797 postrm, on the other hand, is called with the "remove"
3798 argument just after the files are removed, so this is the
3799 proper time to call "ldconfig" to notify the system of the
3800 fact shared libraries from the package are removed.
3801 The postrm can be called at several other times. At the
3802 time of "postrm purge", "postrm abort-install", or "postrm
3803 abort-upgrade", calling "ldconfig" is useless because the
3804 shared lib files are not on-disk. However, when "postrm"
3805 is invoked with arguments "upgrade", "failed-upgrade", or
3806 "disappear", a shared lib may exist on-disk under a
3815 <sect id="sharedlibs-runtime-progs">
3816 <heading>Run-time support programs</heading>
3819 If your package has some run-time support programs which use
3820 the shared library you must not put them in the shared
3821 library package. If you do that then you won't be able to
3822 install several versions of the shared library without
3823 getting filename clashes.
3827 Instead, either create another package for the runtime binaries
3828 (this package might typically be named
3829 <package><var>libraryname</var>-runtime</package>; note the absence
3830 of the <var>soversion</var> in the package name), or if the
3831 development package is small, include them in there.
3835 <sect id="sharedlibs-static">
3836 <heading>Static libraries</heading>
3839 The static library (<file><var>libraryname.a</var></file>)
3840 is usually provided in addition to the shared version.
3841 It is placed into the development package (see below).
3845 In some cases, it is acceptable for a library to be
3846 available in static form only; these cases include:
3848 <item>libraries for languages whose shared library support
3849 is immature or unstable</item>
3850 <item>libraries whose interfaces are in flux or under
3851 development (commonly the case when the library's
3852 major version number is zero, or where the ABI breaks
3853 across patchlevels)</item>
3854 <item>libraries which are explicitly intended to be
3855 available only in static form by their upstream
3860 <sect id="sharedlibs-dev">
3861 <heading>Development files</heading>
3864 The development files associated to a shared library need to be
3865 placed in a package called
3866 <package><var>libraryname</var><var>soversion</var>-dev</package>,
3867 or if you prefer only to support one development version at a
3868 time, <package><var>libraryname</var>-dev</package>.
3872 In case several development versions of a library exist, you may
3873 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
3874 <ref id="conflicts">) to ensure that the user only installs one
3875 development version at a time (as different development versions are
3876 likely to have the same header files in them, which would cause a
3877 filename clash if both were installed).
3881 The development package should contain a symlink for the associated
3882 shared library without a version number. For example, the
3883 <package>libgdbmg1-dev</package> package should include a symlink
3884 from <file>/usr/lib/libgdbm.so</file> to
3885 <file>libgdbm.so.1.7.3</file>. This symlink is needed by the linker
3886 (<prgn>ld</prgn>) when compiling packages, as it will only look for
3887 <file>libgdbm.so</file> when compiling dynamically.
3891 <sect id="sharedlibs-intradeps">
3892 <heading>Dependencies between the packages of the same library</heading>
3895 Typically the development version should have an exact
3896 version dependency on the runtime library, to make sure that
3897 compilation and linking happens correctly. The
3898 <tt>${Source-Version}</tt> substitution variable can be
3899 useful for this purpose.
3903 <sect id="sharedlibs-shlibdeps">
3904 <heading>Dependencies between the library and other packages -
3905 the <tt>shlibs</tt> system</heading>
3908 If a package contains a binary or library which links to a
3909 shared library, we must ensure that when the package is
3910 installed on the system, all of the libraries needed are
3911 also installed. This requirement led to the creation of the
3912 <tt>shlibs</tt> system, which is very simple in its design:
3913 any package which <em>provides</em> a shared library also
3914 provides information on the package dependencies required to
3915 ensure the presence of this library, and any package which
3916 <em>uses</em> a shared library uses this information to
3917 determine the dependencies it requires. The files which
3918 contain the mapping from shared libraries to the necessary
3919 dependency information are called <file>shlibs</file> files.
3923 Thus, when a package is built which contains any shared
3924 libraries, it must provide a <file>shlibs</file> file for other
3925 packages to use, and when a package is built which contains
3926 any shared libraries or compiled binaries, it must run
3927 <prgn>dpkg-shlibdeps</prgn> on these to determine the
3928 libraries used and hence the dependencies needed by this
3931 In the past, the shared libraries linked to were
3932 determined by calling <prgn>ldd</prgn>, but now
3933 <prgn>objdump</prgn> is used to do this. The only
3934 change this makes to package building is that
3935 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
3936 libraries, whereas in the past this was unnecessary.
3937 The rest of this footnote explains the advantage that
3942 We say that a binary <tt>foo</tt> <em>directly</em> uses
3943 a library <tt>libbar</tt> if it is explicitly linked
3944 with that library (that is, it uses the flag
3945 <tt>-lbar</tt> during the linking stage). Other
3946 libraries that are needed by <tt>libbar</tt> are linked
3947 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
3948 linker will load them automatically when it loads
3949 <tt>libbar</tt>. A package should depend on
3950 the libraries it directly uses, and the dependencies for
3951 those libraries should automatically pull in the other
3956 Unfortunately, the <prgn>ldd</prgn> program shows both
3957 the directly and indirectly used libraries, meaning that
3958 the dependencies determined included both direct and
3959 indirect dependencies. The use of <prgn>objdump</prgn>
3960 avoids this problem by determining only the directly
3965 A good example of where this helps is the following. We
3966 could update <tt>libimlib</tt> with a new version that
3967 supports a new graphics format called dgf (but retaining
3968 the same major version number). If we used the old
3969 <prgn>ldd</prgn> method, every package that uses
3970 <tt>libimlib</tt> would need to be recompiled so it
3971 would also depend on <tt>libdgf</tt> or it wouldn't run
3972 due to missing symbols. However with the new system,
3973 packages using <tt>libimlib</tt> can rely on
3974 <tt>libimlib</tt> itself having the dependency on
3975 <tt>libdgf</tt> and so they would not need rebuilding.
3981 In the following sections, we will first describe where the
3982 various <tt>shlibs</tt> files are to be found, then how to
3983 use <prgn>dpkg-shlibdeps</prgn>, and finally the
3984 <tt>shlibs</tt> file format and how to create them if your
3985 package contains a shared library.
3989 <heading>The <tt>shlibs</tt> files present on the system</heading>
3992 There are several places where <tt>shlibs</tt> files are
3993 found. The following list gives them in the order in which
3994 they are read by <prgn>dpkg-shlibdeps</prgn>. (The first
3995 one which gives the required information is used.)
4001 <p><file>debian/shlibs.local</file></p>
4004 This lists overrides for this package. Its use is
4005 described below (see <ref id="shlibslocal">).
4010 <p><file>/etc/dpkg/shlibs.override</file></p>
4013 This lists global overrides. This list is normally
4014 empty. It is maintained by the local system
4020 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
4023 When packages are being built, any
4024 <file>debian/shlibs</file> files are copied into the
4025 control file area of the temporary build directory and
4026 given the name <file>shlibs</file>. These files give
4027 details of any shared libraries included in the
4029 An example may help here. Let us say that the
4030 source package <tt>foo</tt> generates two binary
4031 packages, <tt>libfoo2</tt> and
4032 <tt>foo-runtime</tt>. When building the binary
4033 packages, the two packages are created in the
4034 directories <file>debian/libfoo2</file> and
4035 <file>debian/foo-runtime</file> respectively.
4036 (<file>debian/tmp</file> could be used instead of one
4037 of these.) Since <tt>libfoo2</tt> provides the
4038 <tt>libfoo</tt> shared library, it will require a
4039 <tt>shlibs</tt> file, which will be installed in
4040 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
4042 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
4043 when <prgn>dpkg-shlibdeps</prgn> is run on the
4045 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
4047 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
4048 determine whether <tt>foo-prog</tt>'s library
4049 dependencies are satisfied by any of the libraries
4050 provided by <tt>libfoo2</tt>. For this reason,
4051 <prgn>dpkg-shlibdeps</prgn> must only be run once
4052 all of the individual binary packages'
4053 <tt>shlibs</tt> files have been installed into the
4060 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
4063 These are the <file>shlibs</file> files corresponding to
4064 all of the packages installed on the system, and are
4065 maintained by the relevant package maintainers.
4070 <p><file>/etc/dpkg/shlibs.default</file></p>
4073 This file lists any shared libraries whose packages
4074 have failed to provide correct <file>shlibs</file> files.
4075 It was used when the <file>shlibs</file> setup was first
4076 introduced, but it is now normally empty. It is
4077 maintained by the <tt>dpkg</tt> maintainer.
4085 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
4086 <file>shlibs</file> files</heading>
4089 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
4090 <file>debian/rules</file> file. If your package contains only
4091 compiled binaries and libraries (but no scripts), you can
4092 use a command such as:
4093 <example compact="compact">
4094 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
4095 debian/tmp/usr/lib/*
4097 Otherwise, you will need to explicitly list the compiled
4098 binaries and libraries.<footnote>
4099 If you are using <tt>debhelper</tt>, the
4100 <prgn>dh_shlibdeps</prgn> program will do this work for
4101 you. It will also correctly handle multi-binary
4107 This command puts the dependency information into the
4108 <file>debian/substvars</file> file, which is then used by
4109 <prgn>dpkg-gencontrol</prgn>. You will need to place a
4110 <tt>${shlib:Depends}</tt> variable in the <tt>Depends</tt>
4111 field in the control file for this to work.
4115 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
4116 done. If it does complain you might need to create your own
4117 <file>debian/shlibs.local</file> file, as explained below (see
4118 <ref id="shlibslocal">).
4122 If you have multiple binary packages, you will need to call
4123 <prgn>dpkg-shlibdeps</prgn> on each one which contains
4124 compiled libraries or binaries. In such a case, you will
4125 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
4126 utilities to specify a different <file>substvars</file> file.
4127 For more details on this and other options, see <manref
4128 name="dpkg-shlibdeps" section="1">.
4133 <heading>The <file>shlibs</file> File Format</heading>
4136 Each <file>shlibs</file> file has the same format. Lines
4137 beginning with <tt>#</tt> are considered to be comments and
4138 are ignored. Each line is of the form:
4139 <example compact="compact">
4140 <var>library-name</var> <var>soname-version-number</var> <var>dependencies ...</var>
4145 We will explain this by reference to the example of the
4146 <tt>zlib1g</tt> package, which (at the time of writing)
4147 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
4151 <var>library-name</var> is the name of the shared library,
4152 in this case <tt>libz</tt>. (This must match the name part
4153 of the soname, see below.)
4157 <var>soname-version-number</var> is the version part of the
4158 soname of the library. The soname is the thing that must
4159 exactly match for the library to be recognized by the
4160 dynamic linker, and is usually of the form
4161 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
4162 example, <tt>libz.so.1</tt>.<footnote>
4163 This can be determined using the command
4164 <example compact="compact">
4165 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
4168 The version part is the part which comes after
4169 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
4173 <var>dependencies</var> has the same syntax as a dependency
4174 field in a binary package control file. It should give
4175 details of which packages are required to satisfy a binary
4176 built against the version of the library contained in the
4177 package. See <ref id="depsyntax"> for details.
4181 In our example, if the first version of the <tt>zlib1g</tt>
4182 package which contained a minor number of at least
4183 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
4184 <tt>shlibs</tt> entry for this library could say:
4185 <example compact="compact">
4186 libz 1 zlib1g (>= 1:1.1.3)
4188 The version-specific dependency is to avoid warnings from
4189 the dynamic linker about using older shared libraries with
4195 <heading>Providing a <file>shlibs</file> file</heading>
4198 If your package provides a shared library, you should create
4199 a <file>shlibs</file> file following the format described above.
4200 It is usual to call this file <file>debian/shlibs</file> (but if
4201 you have multiple binary packages, you might want to call it
4202 <file>debian/shlibs.<var>package</var></file> instead). Then
4203 let <file>debian/rules</file> install it in the control area:
4204 <example compact="compact">
4205 install -m644 debian/shlibs debian/tmp/DEBIAN
4207 or, in the case of a multi-binary package:
4208 <example compact="compact">
4209 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
4211 An alternative way of doing this is to create the
4212 <file>shlibs</file> file in the control area directly from
4213 <file>debian/rules</file> without using a <file>debian/shlibs</file>
4214 file at all,<footnote>
4215 This is what <prgn>dh_makeshlibs</prgn> in the
4216 <tt>debhelper</tt> suite does.
4218 since the <file>debian/shlibs</file> file itself is ignored by
4219 <prgn>dpkg-shlibdeps</prgn>.
4223 As <prgn>dpkg-shlibdeps</prgn> reads the
4224 <file>DEBIAN/shlibs</file> files in all of the binary packages
4225 being built from this source package, all of the
4226 <file>DEBIAN/shlibs</file> files should be installed before
4227 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
4232 <sect1 id="shlibslocal">
4233 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
4236 This file is intended only as a <em>temporary</em> fix if
4237 your binaries or libraries depend on a library whose package
4238 does not yet provide a correct <file>shlibs</file> file.
4242 We will assume that you are trying to package a binary
4243 <tt>foo</tt>. When you try running
4244 <prgn>dpkg-shlibdeps</prgn> you get the following error
4245 message (<tt>-O</tt> displays the dependency information on
4246 <tt>stdout</tt> instead of writing it to
4247 <tt>debian/substvars</tt>, and the lines have been wrapped
4248 for ease of reading):
4249 <example compact="compact">
4250 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
4251 dpkg-shlibdeps: warning: unable to find dependency
4252 information for shared library libbar (soname 1,
4253 path /usr/lib/libbar.so.1, dependency field Depends)
4254 shlibs:Depends=libc6 (>= 2.2.2-2)
4256 You can then run <prgn>ldd</prgn> on the binary to find the
4257 full location of the library concerned:
4258 <example compact="compact">
4260 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
4261 libc.so.6 => /lib/libc.so.6 (0x40032000)
4262 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
4264 So the <prgn>foo</prgn> binary depends on the
4265 <prgn>libbar</prgn> shared library, but no package seems to
4266 provide a <file>*.shlibs</file> file handling
4267 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
4268 determine the package responsible:
4269 <example compact="compact">
4270 $ dpkg -S /usr/lib/libbar.so.1
4271 bar1: /usr/lib/libbar.so.1
4272 $ dpkg -s bar1 | grep Version
4275 This tells us that the <tt>bar1</tt> package, version 1.0-1,
4276 is the one we are using. Now we can file a bug against the
4277 <tt>bar1</tt> package and create our own
4278 <file>debian/shlibs.local</file> to locally fix the problem.
4279 Including the following line into your
4280 <file>debian/shlibs.local</file> file:
4281 <example compact="compact">
4282 libbar 1 bar1 (>= 1.0-1)
4284 should allow the package build to work.
4288 As soon as the maintainer of <tt>bar1</tt> provides a
4289 correct <file>shlibs</file> file, you should remove this line
4290 from your <file>debian/shlibs.local</file> file. (You should
4291 probably also then have a versioned <tt>Build-Depends</tt>
4292 on <tt>bar1</tt> to help ensure that others do not have the
4293 same problem building your package.)
4301 <chapt id="opersys"><heading>The Operating System</heading>
4304 <heading>Filesystem hierarchy</heading>
4308 <heading>Filesystem Structure</heading>
4311 The location of all installed files and directories must
4312 comply with the Filesystem Hierarchy Standard (FHS),
4313 version 2.1, except where doing so would violate other
4314 terms of Debian Policy. The version of this document
4315 referred here can be found in the <tt>debian-policy</tt>
4317 <url id="http://www.debian.org/doc/packaging-manuals/fhs/"
4318 name="FHS (Debian copy)"> alongside this manual (or, if
4319 you have the <package>debian-policy</package> installed,
4321 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
4322 (local copy)">). The
4323 latest version, which may be a more recent version, may
4325 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
4326 Specific questions about following the standard may be
4327 asked on the <tt>debian-devel</tt> mailing list, or
4328 referred to the FHS mailing list (see the
4329 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
4335 <heading>Site-specific programs</heading>
4338 As mandated by the FHS, packages must not place any
4339 files in <file>/usr/local</file>, either by putting them in
4340 the file system archive to be unpacked by <prgn>dpkg</prgn>
4341 or by manipulating them in their maintainer scripts.
4345 However, the package may create empty directories below
4346 <file>/usr/local</file> so that the system administrator knows
4347 where to place site-specific files. These directories
4348 should be removed on package removal if they are
4353 Note, that this applies only to directories <em>below</em>
4354 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
4355 Packages must not create sub-directories in the directory
4356 <file>/usr/local</file> itself, except those listed in FHS,
4357 section 4.5. However, you may create directories below
4358 them as you wish. You must not remove any of the
4359 directories listed in 4.5, even if you created them.
4363 Since <file>/usr/local</file> can be mounted read-only from a
4364 remote server, these directories must be created and
4365 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
4366 maintainer scripts and not be included in the
4367 <file>.deb</file> archive. These scripts must not fail if
4368 either of these operations fail.
4372 For example, the <tt>emacsen-common</tt> package could
4373 contain something like
4374 <example compact="compact">
4375 if [ ! -e /usr/local/share/emacs ]
4377 if mkdir /usr/local/share/emacs 2>/dev/null
4379 chown root:staff /usr/local/share/emacs
4380 chmod 2775 /usr/local/share/emacs
4384 in its <prgn>postinst</prgn> script, and
4385 <example compact="compact">
4386 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
4387 rmdir /usr/local/share/emacs 2>/dev/null || true
4389 in the <prgn>prerm</prgn> script. (Note that this form is
4390 used to ensure that if the script is interrupted, the
4391 directory <file>/usr/local/share/emacs</file> will still be
4396 If you do create a directory in <file>/usr/local</file> for
4397 local additions to a package, you should ensure that
4398 settings in <file>/usr/local</file> take precedence over the
4399 equivalents in <file>/usr</file>.
4403 However, because <file>/usr/local</file> and its contents are
4404 for exclusive use of the local administrator, a package
4405 must not rely on the presence or absence of files or
4406 directories in <file>/usr/local</file> for normal operation.
4410 The <file>/usr/local</file> directory itself and all the
4411 subdirectories created by the package should (by default) have
4412 permissions 2775 (group-writable and set-group-id) and be
4413 owned by <tt>root.staff</tt>.
4418 <heading>The system-wide mail directory</heading>
4420 The system-wide mail directory is <file>/var/mail</file>. This
4421 directory is part of the base system and should not owned
4422 by any particular mail agents. The use of the old
4423 location <file>/var/spool/mail</file> is deprecated, even
4424 though the spool may still be physically located there.
4425 To maintain partial upgrade compatibility for systems
4426 which have <file>/var/spool/mail</file> as their physical mail
4427 spool, packages using <file>/var/mail</file> must depend on
4428 either <package>libc6</package> (>= 2.1.3-13), or on
4429 <package>base-files</package> (>= 2.2.0), or on later
4430 versions of either one of these packages.
4436 <heading>Users and groups</heading>
4439 <heading>Introduction</heading>
4441 The Debian system can be configured to use either plain or
4446 Some user ids (UIDs) and group ids (GIDs) are reserved
4447 globally for use by certain packages. Because some
4448 packages need to include files which are owned by these
4449 users or groups, or need the ids compiled into binaries,
4450 these ids must be used on any Debian system only for the
4451 purpose for which they are allocated. This is a serious
4452 restriction, and we should avoid getting in the way of
4453 local administration policies. In particular, many sites
4454 allocate users and/or local system groups starting at 100.
4458 Apart from this we should have dynamically allocated ids,
4459 which should by default be arranged in some sensible
4460 order, but the behavior should be configurable.
4464 Packages other than <tt>base-passwd</tt> must not modify
4465 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
4466 <file>/etc/group</file> or <file>/etc/gshadow</file>.
4471 <heading>UID and GID classes</heading>
4473 The UID and GID numbers are divided into classes as
4479 Globally allocated by the Debian project, the same
4480 on every Debian system. These ids will appear in
4481 the <file>passwd</file> and <file>group</file> files of all
4482 Debian systems, new ids in this range being added
4483 automatically as the <tt>base-passwd</tt> package is
4488 Packages which need a single statically allocated
4489 uid or gid should use one of these; their
4490 maintainers should ask the <tt>base-passwd</tt>
4498 Dynamically allocated system users and groups.
4499 Packages which need a user or group, but can have
4500 this user or group allocated dynamically and
4501 differently on each system, should use <tt>adduser
4502 --system</tt> to create the group and/or user.
4503 <prgn>adduser</prgn> will check for the existence of
4504 the user or group, and if necessary choose an unused
4505 id based on the ranges specified in
4506 <file>adduser.conf</file>.
4510 <tag>1000-29999:</tag>
4513 Dynamically allocated user accounts. By default
4514 <prgn>adduser</prgn> will choose UIDs and GIDs for
4515 user accounts in this range, though
4516 <file>adduser.conf</file> may be used to modify this
4521 <tag>30000-59999:</tag>
4526 <tag>60000-64999:</tag>
4529 Globally allocated by the Debian project, but only
4530 created on demand. The ids are allocated centrally
4531 and statically, but the actual accounts are only
4532 created on users' systems on demand.
4536 These ids are for packages which are obscure or
4537 which require many statically-allocated ids. These
4538 packages should check for and create the accounts in
4539 <file>/etc/passwd</file> or <file>/etc/group</file> (using
4540 <prgn>adduser</prgn> if it has this facility) if
4541 necessary. Packages which are likely to require
4542 further allocations should have a "hole" left after
4543 them in the allocation, to give them room to
4548 <tag>65000-65533:</tag>
4556 User <tt>nobody</tt>. The corresponding gid refers
4557 to the group <tt>nogroup</tt>.
4564 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
4565 not</em> be used, because it is the error return
4574 <sect id="sysvinit">
4575 <heading>System run levels and <file>init.d</file> scripts</heading>
4577 <sect1 id="/etc/init.d">
4578 <heading>Introduction</heading>
4581 The <file>/etc/init.d</file> directory contains the scripts
4582 executed by <prgn>init</prgn> at boot time and when the
4583 init state (or "runlevel") is changed (see <manref
4584 name="init" section="8">).
4588 There are at least two different, yet functionally
4589 equivalent, ways of handling these scripts. For the sake
4590 of simplicity, this document describes only the symbolic
4591 link method. However, it must not be assumed by maintainer
4592 scripts that this method is being used, and any automated
4593 manipulation of the various runlevel behaviours by
4594 maintainer scripts must be performed using
4595 <prgn>update-rc.d</prgn> as described below and not by
4596 manually installing or removing symlinks. For information
4597 on the implementation details of the other method,
4598 implemented in the <tt>file-rc</tt> package, please refer
4599 to the documentation of that package.
4603 These scripts are referenced by symbolic links in the
4604 <file>/etc/rc<var>n</var>.d</file> directories. When changing
4605 runlevels, <prgn>init</prgn> looks in the directory
4606 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
4607 execute, where <tt><var>n</var></tt> is the runlevel that
4608 is being changed to, or <tt>S</tt> for the boot-up
4613 The names of the links all have the form
4614 <file>S<var>mm</var><var>script</var></file> or
4615 <file>K<var>mm</var><var>script</var></file> where
4616 <var>mm</var> is a two-digit number and <var>script</var>
4617 is the name of the script (this should be the same as the
4618 name of the actual script in <file>/etc/init.d</file>).
4622 When <prgn>init</prgn> changes runlevel first the targets
4623 of the links whose names start with a <tt>K</tt> are
4624 executed, each with the single argument <tt>stop</tt>,
4625 followed by the scripts prefixed with an <tt>S</tt>, each
4626 with the single argument <tt>start</tt>. (The links are
4627 those in the <file>/etc/rc<var>n</var>.d</file> directory
4628 corresponding to the new runlevel.) The <tt>K</tt> links
4629 are responsible for killing services and the <tt>S</tt>
4630 link for starting services upon entering the runlevel.
4634 For example, if we are changing from runlevel 2 to
4635 runlevel 3, init will first execute all of the <tt>K</tt>
4636 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
4637 all of the <tt>S</tt> prefixed scripts in that directory.
4638 The links starting with <tt>K</tt> will cause the
4639 referred-to file to be executed with an argument of
4640 <tt>stop</tt>, and the <tt>S</tt> links with an argument
4645 The two-digit number <var>mm</var> is used to determine
4646 the order in which to run the scripts: low-numbered links
4647 have their scripts run first. For example, the
4648 <tt>K20</tt> scripts will be executed before the
4649 <tt>K30</tt> scripts. This is used when a certain service
4650 must be started before another. For example, the name
4651 server <prgn>bind</prgn> might need to be started before
4652 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
4653 can set up its access lists. In this case, the script
4654 that starts <prgn>bind</prgn> would have a lower number
4655 than the script that starts <prgn>inn</prgn> so that it
4657 <example compact="compact">
4664 The two runlevels 0 (halt) and 6 (reboot) are slightly
4665 different. In these runlevels, the links with an
4666 <tt>S</tt> prefix are still called after those with a
4667 <tt>K</tt> prefix, but they too are called with the single
4668 argument <tt>stop</tt>.
4672 Also, if the script name ends <tt>.sh</tt>, the script
4673 will be sourced in runlevel <tt>S</tt> rather that being
4674 run in a forked subprocess, but will be explicitly run by
4675 <prgn>sh</prgn> in all other runlevels.
4680 <heading>Writing the scripts</heading>
4683 Packages that include daemons for system services should
4684 place scripts in <file>/etc/init.d</file> to start or stop
4685 services at boot time or during a change of runlevel.
4686 These scripts should be named
4687 <file>/etc/init.d/<var>package</var></file>, and they should
4688 accept one argument, saying what to do:
4691 <tag><tt>start</tt></tag>
4692 <item>start the service,</item>
4694 <tag><tt>stop</tt></tag>
4695 <item>stop the service,</item>
4697 <tag><tt>restart</tt></tag>
4698 <item>stop and restart the service if it's already running,
4699 otherwise start the service</item>
4701 <tag><tt>reload</tt></tag>
4702 <item><p>cause the configuration of the service to be
4703 reloaded without actually stopping and restarting
4706 <tag><tt>force-reload</tt></tag>
4707 <item>cause the configuration to be reloaded if the
4708 service supports this, otherwise restart the
4712 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
4713 <tt>force-reload</tt> options should be supported by all
4714 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
4719 The <file>init.d</file> scripts should ensure that they will
4720 behave sensibly if invoked with <tt>start</tt> when the
4721 service is already running, or with <tt>stop</tt> when it
4722 isn't, and that they don't kill unfortunately-named user
4723 processes. The best way to achieve this is usually to use
4724 <prgn>start-stop-daemon</prgn>.
4728 If a service reloads its configuration automatically (as
4729 in the case of <prgn>cron</prgn>, for example), the
4730 <tt>reload</tt> option of the <file>init.d</file> script
4731 should behave as if the configuration has been reloaded
4736 The <file>/etc/init.d</file> scripts must be treated as
4737 configuration files, either (if they are present in the
4738 package, that is, in the .deb file) by marking them as
4739 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
4740 by managing them correctly in the maintainer scripts (see
4741 <ref id="config-files">). This is important since we want
4742 to give the local system administrator the chance to adapt
4743 the scripts to the local system, e.g., to disable a
4744 service without de-installing the package, or to specify
4745 some special command line options when starting a service,
4746 while making sure her changes aren't lost during the next
4751 These scripts should not fail obscurely when the
4752 configuration files remain but the package has been
4753 removed, as configuration files remain on the system after
4754 the package has been removed. Only when <prgn>dpkg</prgn>
4755 is executed with the <tt>--purge</tt> option will
4756 configuration files be removed. In particular, as the
4757 <file>/etc/init.d/<var>package</var></file> script itself is
4758 usually a <tt>conffile</tt>, it will remain on the system
4759 if the package is removed but not purged. Therefore, you
4760 should include a <tt>test</tt> statement at the top of the
4762 <example compact="compact">
4763 test -f <var>program-executed-later-in-script</var> || exit 0
4768 Often there are some variables in the <file>init.d</file>
4769 scripts whose values control the behaviour of the scripts,
4770 and which a system administrator is likely to want to
4771 change. As the scripts themselves are frequently
4772 <tt>conffile</tt>s, modifying them requires that the
4773 administrator merge in their changes each time the package
4774 is upgraded and the <tt>conffile</tt> changes. To ease
4775 the burden on the system administrator, such configurable
4776 values should not be placed directly in the script.
4777 Instead, they should be placed in a file in
4778 <file>/etc/default</file>, which typically will have the same
4779 base name as the <file>init.d</file> script. This extra file
4780 should be sourced by the script when the script runs. It
4781 must contain only variable settings and comments in POSIX
4782 <prgn>sh</prgn> format. It may either be a
4783 <tt>conffile</tt> or a configuration file maintained by
4784 the package maintainer scripts. See <ref id="config-files">
4789 To ensure that vital configurable values are always
4790 available, the <file>init.d</file> script should set default
4791 values for each of the shell variables it uses, either
4792 before sourcing the <file>/etc/default/</file> file or
4793 afterwards using something like the <tt>:
4794 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
4795 script must behave sensibly and not fail if the
4796 <file>/etc/default</file> file is deleted.
4801 <heading>Interfacing with the initscript system</heading>
4804 Maintainers should use the abstraction layer provided by
4805 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
4806 programs to deal with initscripts in their packages'
4807 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
4808 and <prgn>postrm</prgn>.
4812 Directly managing the /etc/rc?.d links and directly
4813 invoking the <file>/etc/init.d/</file> initscripts should
4814 be done only by packages providing the initscript
4815 subsystem (such as <prgn>sysvinit</prgn> and
4816 <prgn>file-rc</prgn>).
4820 <heading>Managing the links</heading>
4823 The program <prgn>update-rc.d</prgn> is provided for
4824 package maintainers to arrange for the proper creation and
4825 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
4826 or their functional equivalent if another method is being
4827 used. This may be used by maintainers in their packages'
4828 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
4832 You must not include any <file>/etc/rc<var>n</var>.d</file>
4833 symbolic links in the actual archive or manually create or
4834 remove the symbolic links in maintainer scripts; you must
4835 use the <prgn>update-rc.d</prgn> program instead. (The
4836 former will fail if an alternative method of maintaining
4837 runlevel information is being used.) You must not include
4838 the <file>/etc/rc<var>n</var>.d</file> directories themselves
4839 in the archive either. (Only the <tt>sysvinit</tt>
4844 By default <prgn>update-rc.d</prgn> will start services in
4845 each of the multi-user state runlevels (2, 3, 4, and 5)
4846 and stop them in the halt runlevel (0), the single-user
4847 runlevel (1) and the reboot runlevel (6). The system
4848 administrator will have the opportunity to customize
4849 runlevels by simply adding, moving, or removing the
4850 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
4851 symbolic links are being used, or by modifying
4852 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
4857 To get the default behavior for your package, put in your
4858 <prgn>postinst</prgn> script
4859 <example compact="compact">
4860 update-rc.d <var>package</var> defaults
4862 and in your <prgn>postrm</prgn>
4863 <example compact="compact">
4864 if [ "$1" = purge ]; then
4865 update-rc.d <var>package</var> remove
4867 </example>. Note that if your package changes runlevels
4868 or priority, you may have to remove and recreate the links,
4869 since otherwise the old links may persist. Refer to the
4870 documentation of <prgn>update-rc.d</prgn>.
4874 This will use a default sequence number of 20. If it does
4875 not matter when or in which order the <file>init.d</file>
4876 script is run, use this default. If it does, then you
4877 should talk to the maintainer of the <prgn>sysvinit</prgn>
4878 package or post to <tt>debian-devel</tt>, and they will
4879 help you choose a number.
4883 For more information about using <tt>update-rc.d</tt>,
4884 please consult its manpage <manref name="update-rc.d"
4890 <heading>Running initscripts</heading>
4892 The program <prgn>invoke-rc.d</prgn> is provided to make
4893 it easier for package maintainers to properly invoke an
4894 initscript, obeying runlevel and other locally-defined
4895 constraints that might limit a package's right to start,
4896 stop and otherwise manage services. This program may be
4897 used by maintainers in their packages' scripts.
4901 The use of <prgn>invoke-rc.d</prgn> to invoke the
4902 <file>/etc/init.d/*</file> initscripts is strongly
4903 recommended<footnote>
4904 In the future, the use of invoke-rc.d to invoke
4905 initscripts shall be made mandatory. Maintainers are
4906 advised to switch to invoke-rc.d as soon as
4908 </footnote>, instead of calling them directly.
4912 By default, <prgn>invoke-rc.d</prgn> will pass any
4913 action requests (start, stop, reload, restart...) to the
4914 <file>/etc/init.d</file> script, filtering out requests
4915 to start or restart a service out of its intended
4920 Most packages will simply need to change:
4921 <example compact="compact">/etc/init.d/<package>
4922 <action></example> in their <prgn>postinst</prgn>
4923 and <prgn>prerm</prgn> scripts to:
4924 <example compact="compact">
4925 if [ -x /usr/sbin/invoke-rc.d ] ; then
4926 invoke-rc.d <var>package</var> <action>
4928 /etc/init.d/<var>package</var> <action>
4934 A package should register its initscript services using
4935 <prgn>update-rc.d</prgn> before it tries to invoke them
4936 using <prgn>invoke-rc.d</prgn>. Invocation of
4937 unregistered services may fail.
4941 For more information about using
4942 <prgn>invoke-rc.d</prgn>, please consult its manpage
4943 <manref name="invoke-rc.d" section="8">.
4949 <heading>Boot-time initialization</heading>
4952 There used to be another directory, <file>/etc/rc.boot</file>,
4953 which contained scripts which were run once per machine
4954 boot. This has been deprecated in favour of links from
4955 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
4956 described in <ref id="/etc/init.d">. Packages must not
4957 place files in <file>/etc/rc.boot</file>.
4962 <heading>Example</heading>
4965 The <prgn>bind</prgn> DNS (nameserver) package wants to
4966 make sure that the nameserver is running in multiuser
4967 runlevels, and is properly shut down with the system. It
4968 puts a script in <file>/etc/init.d</file>, naming the script
4969 appropriately <tt>bind</tt>. As you can see, the script
4970 interprets the argument <tt>reload</tt> to send the
4971 nameserver a <tt>HUP</tt> signal (causing it to reload its
4972 configuration); this way the system administrator can say
4973 <tt>/etc/init.d/bind reload</tt> to reload the name
4974 server. The script has one configurable value, which can
4975 be used to pass parameters to the named program at
4976 startup; this value is read from
4977 <file>/etc/default/bind</file> (see below).
4981 <example compact="compact">
4984 # Original version by Robert Leslie
4985 # <rob@mars.org>, edited by iwj and cs
4987 test -x /usr/sbin/named || exit 0
4989 # Source defaults file.
4991 if [ -f /etc/default/bind ]; then
4998 echo -n "Starting domain name service: named"
4999 start-stop-daemon --start --quiet --exec /usr/sbin/named \
5004 echo -n "Stopping domain name service: named"
5005 start-stop-daemon --stop --quiet \
5006 --pidfile /var/run/named.pid --exec /usr/sbin/named
5010 echo -n "Restarting domain name service: named"
5011 start-stop-daemon --stop --quiet \
5012 --pidfile /var/run/named.pid --exec /usr/sbin/named
5013 start-stop-daemon --start --verbose --exec /usr/sbin/named \
5017 force-reload|reload)
5018 echo -n "Reloading configuration of domain name service: named"
5019 start-stop-daemon --stop --signal 1 --quiet \
5020 --pidfile /var/run/named.pid --exec /usr/sbin/named
5024 echo "Usage: /etc/init.d/bind " \
5025 " {start|stop|restart|reload|force-reload}" >&2
5035 Complementing the above init script is a configuration
5036 file <file>/etc/default/bind</file>, which contains
5037 configurable parameters used by the script. This would be
5038 created by the <prgn>postinst</prgn> script if it was not
5039 already present, and removed on purge by the
5040 <prgn>postrm</prgn> script.
5041 <example compact="compact">
5042 # Specified parameters to pass to named. See named(8).
5043 # You may uncomment the following line, and edit to taste.
5049 Another example on which you can base your
5050 <file>/etc/init.d</file> scripts is found in
5051 <file>/etc/init.d/skeleton</file>.
5055 If this package is happy with the default setup from
5056 <prgn>update-rc.d</prgn>, namely an ordering number of 20
5057 and having named running in all runlevels, it can say in
5058 its <prgn>postinst</prgn>:
5059 <example compact="compact">
5060 update-rc.d bind defaults >/dev/null
5062 And in its <prgn>postrm</prgn>, to remove the links when the
5064 <example compact="compact">
5065 if [ "$1" = purge ]; then
5066 update-rc.d bind remove >/dev/null
5074 <heading>Console messages from <file>init.d</file> scripts</heading>
5077 This section describes the formats to be used for messages
5078 written to standard output by the <file>/etc/init.d</file>
5079 scripts. The intent is to improve the consistency of
5080 Debian's startup and shutdown look and feel. For this
5081 reason, please look very carefully at the details. We want
5082 the messages to have the same format in terms of wording,
5083 spaces, punctuation and case of letters.
5087 Here is a list of overall rules that you should use when you
5088 create output messages. They can be useful if you have a
5089 non-standard message that is not covered specifically in the
5096 Every message should fit in one line (fewer than 80
5097 characters), start with a capital letter and end with
5098 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
5102 If you want to express that the computer is working on
5103 something (that is, performing a specific task, not
5104 starting or stopping a program), we use an "ellipsis"
5105 (three dots: <tt>...</tt>). Note that we don't insert
5106 spaces before or after the dots. If the task has been
5107 completed we write <tt>done.</tt> and a line feed.
5111 Design your messages as if the computer is telling you
5112 what he is doing (let him be polite :-), but don't
5113 mention "him" directly. For example, if you think of
5115 <example compact="compact">
5116 I'm starting network daemons: nfsd mountd.
5119 <example compact="compact">
5120 Starting network daemons: nfsd mountd.
5127 There are standard message formats for the following
5128 situations. They should be used by the <tt>init.d</tt>
5135 <p>When daemons are started</p>
5138 If your script starts one or more daemons, the output
5139 should look like this (a single line, no leading
5141 <example compact="compact">
5142 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
5144 The <var>description</var> should describe the
5145 subsystem the daemon or set of daemons are part of,
5146 while <var>daemon-1</var> up to <var>daemon-n</var>
5147 denote each daemon's name (typically the file name of
5152 For example, the output of <file>/etc/init.d/lpd</file>
5154 <example compact="compact">
5155 Starting printer spooler: lpd.
5160 This can be achieved by saying
5161 <example compact="compact">
5162 echo -n "Starting printer spooler: lpd"
5163 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
5166 in the script. If you have more than one daemon to
5167 start, you should do the following:
5168 <example compact="compact">
5169 echo -n "Starting remote file system services:"
5170 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
5171 echo -n " mountd"; start-stop-daemon --start --quiet mountd
5172 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
5175 This makes it possible for the user to see what takes
5176 so long and when the final daemon has been started.
5177 You should be careful where to put spaces: in the
5178 example above the system administrator can easily
5179 comment out a line if he don't wants to start a
5180 specific daemon, while the displayed message still
5186 <p>When a system parameter is being set</p>
5189 If you have to set up different system parameters
5190 during the system boot, you should use this format:
5191 <example compact="compact">
5192 Setting <var>parameter</var> to "<var>value</var>".
5197 You can use a statement such as the following to get
5199 <example compact="compact">
5200 echo "Setting DNS domainname to \"$domainname\"."
5205 Note that the same symbol (<tt>"</tt>) is used for the left
5206 and right quotation marks. A grave accent (<tt>`</tt>) is
5207 not a quote character; neither is an apostrophe
5213 <p>When a daemon is stopped or restarted</p>
5216 When you stop or restart a daemon, you should issue a
5217 message identical to the startup message, except that
5218 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
5219 or <tt>Restarting</tt> respectively.
5223 For example, stopping the printer daemon will like
5225 <example compact="compact">
5226 Stopping printer spooler: lpd.
5232 <p>When something is executed</p>
5235 There are several examples where you have to run a
5236 program at system startup or shutdown to perform a
5237 specific task, for example, setting the system's clock
5238 using <prgn>netdate</prgn> or killing all processes
5239 when the system shuts down. Your message should look
5241 <example compact="compact">
5242 Doing something very useful...done.
5244 You should print the <tt>done.</tt> immediately after
5245 the job has been completed, so that the user is
5246 informed why she has to wait. You can get this
5248 <example compact="compact">
5249 echo -n "Doing something very useful..."
5258 <p>When the configuration is reloaded</p>
5261 When a daemon is forced to reload its configuration
5262 files you should use the following format:
5263 <example compact="compact">
5264 Reloading <var>description</var> configuration...done.
5266 where <var>description</var> is the same as in the
5267 daemon starting message.
5275 <heading>Cron jobs</heading>
5278 Packages must not modify the configuration file
5279 <file>/etc/crontab</file>, and they must not modify the files in
5280 <file>/var/spool/cron/crontabs</file>.</p>
5283 If a package wants to install a job that has to be executed
5284 via cron, it should place a file with the name of the
5285 package in one or more of the following directories:
5286 <example compact="compact">
5291 As these directory names imply, the files within them are
5292 executed on a daily, weekly, or monthly basis,
5293 respectively. The exact times are listed in
5294 <file>/etc/crontab</file>.</p>
5297 All files installed in any of these directories must be
5298 scripts (e.g., shell scripts or Perl scripts) so that they
5299 can easily be modified by the local system administrator.
5300 In addition, they should be treated as configuration
5305 If a certain job has to be executed more frequently than
5306 daily, the package should install a file
5307 <file>/etc/cron.d/<var>package</var></file>. This file uses the
5308 same syntax as <file>/etc/crontab</file> and is processed by
5309 <prgn>cron</prgn> automatically. The file must also be
5310 treated as a configuration file. (Note that entries in the
5311 <file>/etc/cron.d</file> directory are not handled by
5312 <prgn>anacron</prgn>. Thus, you should only use this
5313 directory for jobs which may be skipped if the system is not
5317 The scripts or crontab entries in these directories should
5318 check if all necessary programs are installed before they
5319 try to execute them. Otherwise, problems will arise when a
5320 package was removed but not purged since configuration files
5321 are kept on the system in this situation.</p>
5325 <heading>Menus</heading>
5328 The Debian <tt>menu</tt> package provides a standard
5329 interface between packages providing applications and
5330 documents, and <em>menu programs</em> (either X window
5331 managers or text-based menu programs such as
5332 <prgn>pdmenu</prgn>).
5336 All packages that provide applications that need not be
5337 passed any special command line arguments for normal
5338 operation should register a menu entry for those
5339 applications, so that users of the <tt>menu</tt> package
5340 will automatically get menu entries in their window
5341 managers, as well in shells like <tt>pdmenu</tt>.
5345 Menu entries should follow the current menu policy.
5349 The menu policy can be found in the <tt>menu-policy</tt>
5350 files in the <tt>debian-policy</tt> package.
5351 They are also available from the Debian web mirrors at
5352 <tt><url name="/doc/packaging-manuals/menu-policy/"
5353 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>
5354 and from the Debian archive mirrors at
5355 <tt><url name="/doc/package-developer/menu-policy.txt.gz"
5356 id="http://ftp.debian.org/debian/doc/package-developer/menu-policy.txt.gz"></tt>.
5360 Please also refer to the <em>Debian Menu System</em>
5361 documentation that comes with the <tt>menu</tt> package for
5362 information about how to register your applications and web
5368 <heading>Multimedia handlers</heading>
5371 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
5372 is a mechanism for encoding files and data streams and
5373 providing meta-information about them, in particular their
5374 type (e.g. audio or video) and format (e.g. PNG, HTML,
5379 Registration of MIME type handlers allows programs like mail
5380 user agents and web browsers to to invoke these handlers to
5381 view, edit or display MIME types they don't support
5386 Packages which provide the ability to view/show/play,
5387 compose, edit or print MIME types should register themselves
5388 as such following the current MIME support policy.
5392 The MIME support policy can be found in the <tt>mime-policy</tt>
5393 files in the <tt>debian-policy</tt> package.
5394 They are also available from the Debian web mirrors at
5395 <tt><url name="/doc/packaging-manuals/mime-policy/"
5396 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>
5397 and from the Debian archive mirrors at
5398 <tt><url name="/doc/package-developer/mime-policy.txt.gz"
5399 id="http://ftp.debian.org/debian/doc/package-developer/mime-policy.txt.gz"></tt>.
5405 <heading>Keyboard configuration</heading>
5408 To achieve a consistent keyboard configuration so that all
5409 applications interpret a keyboard event the same way, all
5410 programs in the Debian distribution must be configured to
5411 comply with the following guidelines.
5415 The following keys must have the specified interpretations:
5418 <tag><tt><--</tt></tag>
5419 <item>delete the character to the left of the cursor</item>
5421 <tag><tt>Delete</tt></tag>
5422 <item>delete the character to the right of the cursor</item>
5424 <tag><tt>Control+H</tt></tag>
5425 <item>emacs: the help prefix</item>
5428 The interpretation of any keyboard events should be
5429 independent of the terminal that is used, be it a virtual
5430 console, an X terminal emulator, an rlogin/telnet session,
5435 The following list explains how the different programs
5436 should be set up to achieve this:
5442 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
5446 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
5450 X translations are set up to make
5451 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
5452 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
5453 is the vt220 escape code for the "delete character"
5454 key). This must be done by loading the X resources
5455 using <prgn>xrdb</prgn> on all local X displays, not
5456 using the application defaults, so that the
5457 translation resources used correspond to the
5458 <prgn>xmodmap</prgn> settings.
5462 The Linux console is configured to make
5463 <tt><--</tt> generate DEL, and <tt>Delete</tt>
5464 generate <tt>ESC [ 3 ~</tt>.
5468 X applications are configured so that <tt><</tt>
5469 deletes left, and <tt>Delete</tt> deletes right. Motif
5470 applications already work like this.
5474 Terminals should have <tt>stty erase ^?</tt> .
5478 The <tt>xterm</tt> terminfo entry should have <tt>ESC
5479 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
5480 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
5484 Emacs is programmed to map <tt>KB_Backspace</tt> or
5485 the <tt>stty erase</tt> character to
5486 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
5487 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
5488 <tt>^H</tt> to <tt>help</tt> as always.
5492 Other applications use the <tt>stty erase</tt>
5493 character and <tt>kdch1</tt> for the two delete keys,
5494 with ASCII DEL being "delete previous character" and
5495 <tt>kdch1</tt> being "delete character under
5503 This will solve the problem except for the following
5510 Some terminals have a <tt><--</tt> key that cannot
5511 be made to produce anything except <tt>^H</tt>. On
5512 these terminals Emacs help will be unavailable on
5513 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
5514 character takes precedence in Emacs, and has been set
5515 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
5516 available) can be used instead.
5520 Some operating systems use <tt>^H</tt> for <tt>stty
5521 erase</tt>. However, modern telnet versions and all
5522 rlogin versions propagate <tt>stty</tt> settings, and
5523 almost all UNIX versions honour <tt>stty erase</tt>.
5524 Where the <tt>stty</tt> settings are not propagated
5525 correctly, things can be made to work by using
5526 <tt>stty</tt> manually.
5530 Some systems (including previous Debian versions) use
5531 <prgn>xmodmap</prgn> to arrange for both
5532 <tt><--</tt> and <tt>Delete</tt> to generate
5533 <tt>KB_Delete</tt>. We can change the behavior of
5534 their X clients using the same X resources that we use
5535 to do it for our own clients, or configure our clients
5536 using their resources when things are the other way
5537 around. On displays configured like this
5538 <tt>Delete</tt> will not work, but <tt><--</tt>
5543 Some operating systems have different <tt>kdch1</tt>
5544 settings in their <tt>terminfo</tt> database for
5545 <tt>xterm</tt> and others. On these systems the
5546 <tt>Delete</tt> key will not work correctly when you
5547 log in from a system conforming to our policy, but
5548 <tt><--</tt> will.
5555 <heading>Environment variables</heading>
5558 A program must not depend on environment variables to get
5559 reasonable defaults. (That's because these environment
5560 variables would have to be set in a system-wide
5561 configuration file like <file>/etc/profile</file>, which is not
5562 supported by all shells.)
5566 If a program usually depends on environment variables for its
5567 configuration, the program should be changed to fall back to
5568 a reasonable default configuration if these environment
5569 variables are not present. If this cannot be done easily
5570 (e.g., if the source code of a non-free program is not
5571 available), the program must be replaced by a small
5572 "wrapper" shell script which sets the environment variables
5573 if they are not already defined, and calls the original program.
5577 Here is an example of a wrapper script for this purpose:
5579 <example compact="compact">
5581 BAR=${BAR:-/var/lib/fubar}
5583 exec /usr/lib/foo/foo "$@"
5588 Furthermore, as <file>/etc/profile</file> is a configuration
5589 file of the <prgn>base-files</prgn> package, other packages must not
5590 put any environment variables or other commands into that
5599 <heading>Files</heading>
5602 <heading>Binaries</heading>
5605 Two different packages must not install programs with
5606 different functionality but with the same filenames. (The
5607 case of two programs having the same functionality but
5608 different implementations is handled via "alternatives" or
5609 the "Conflicts" mechanism. See <ref id="maintscripts"> and
5610 <ref id="conflicts"> respectively.) If this case happens,
5611 one of the programs must be renamed. The maintainers should
5612 report this to the <tt>debian-devel</tt> mailing list and
5613 try to find a consensus about which program will have to be
5614 renamed. If a consensus cannot be reached, <em>both</em>
5615 programs must be renamed.
5619 By default, when a package is being built, any binaries
5620 created should include debugging information, as well as
5621 being compiled with optimization. You should also turn on
5622 as many reasonable compilation warnings as possible; this
5623 makes life easier for porters, who can then look at build
5624 logs for possible problems. For the C programming language,
5625 this means the following compilation parameters should be
5627 <example compact="compact">
5629 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
5631 install -s # (or use strip on the files in debian/tmp)
5636 Note that by default all installed binaries should be stripped,
5637 either by using the <tt>-s</tt> flag to
5638 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
5639 the binaries after they have been copied into
5640 <file>debian/tmp</file> but before the tree is made into a
5645 Although binaries in the build tree should be compiled with
5646 debugging information by default, it can often be difficult
5647 to debug programs if they are also subjected to compiler
5648 optimization. For this reason, it is recommended to support
5649 the standardized environment
5650 variable <tt>DEB_BUILD_OPTIONS</tt>. This variable can
5651 contain several flags to change how a package is compiled
5659 The presence of this string means that the package
5660 should be compiled with a minimum of optimization.
5661 For C programs, it is best to add <tt>-O0</tt>
5662 to <tt>CFLAGS</tt> (although this is usually the
5663 default). Some programs might fail to build or run at
5664 this level of optimization; it may be necessary to
5665 use <tt>-O1</tt>, for example.
5669 This string means that the debugging symbols should
5670 not be stripped from the binary during installation,
5671 so that debugging information may be included in the package.
5677 The following makefile snippet is an example of how one may
5678 implement the build options; you will probably have to
5679 massage this example in order to make it work for your
5681 <example compact="compact">
5684 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
5685 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
5686 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
5687 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
5689 ifneq (,$(findstring noopt,$(DEB_BUILD_OPTIONS)))
5694 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
5695 INSTALL_PROGRAM += -s
5701 It is up to the package maintainer to decide what
5702 compilation options are best for the package. Certain
5703 binaries (such as computationally-intensive programs) will
5704 function better with certain flags (<tt>-O3</tt>, for
5705 example); feel free to use them. Please use good judgment
5706 here. Don't use flags for the sake of it; only use them
5707 if there is good reason to do so. Feel free to override
5708 the upstream author's ideas about which compilation
5709 options are best: they are often inappropriate for our
5715 <sect id="libraries">
5716 <heading>Libraries</heading>
5719 The shared version of a library must be compiled with
5720 <tt>-fPIC</tt>, and the static version must not be. In other
5721 words, each source unit (<tt>*.c</tt>, for example, for C files)
5722 will need to be compiled twice.
5726 You must specify the gcc option <tt>-D_REENTRANT</tt>
5727 when building a library (either static or shared) to make
5728 the library compatible with LinuxThreads.
5732 All installed shared libraries should be stripped with
5733 <example compact="compact">
5734 strip --strip-unneeded <var>your-lib</var>
5736 (The option <tt>--strip-unneeded</tt> makes
5737 <prgn>strip</prgn> remove only the symbols which aren't
5738 needed for relocation processing.) Shared libraries can
5739 function perfectly well when stripped, since the symbols for
5740 dynamic linking are in a separate part of the ELF object
5742 You might also want to use the options
5743 <tt>--remove-section=.comment</tt> and
5744 <tt>--remove-section=.note</tt> on both shared libraries
5745 and executables, and <tt>--strip-debug</tt> on static
5751 Note that under some circumstances it may be useful to
5752 install a shared library unstripped, for example when
5753 building a separate package to support debugging.
5757 Shared object files (often <file>.so</file> files) that are not
5758 public libraries, that is, they are not meant to be linked
5759 to by third party executables (binaries of other packages),
5760 should be installed in subdirectories of the
5761 <file>/usr/lib</file> directory. Such files are exempt from the
5762 rules that govern ordinary shared libraries, except that
5763 they must not be installed executable and should be
5765 A common example are the so-called "plug-ins",
5766 internal shared objects that are dynamically loaded by
5767 programs using <manref name="dlopen" section="3">.
5772 Packages containing shared libraries that may be linked to
5773 by other packages' binaries, but which for some
5774 <em>compelling</em> reason can not be installed in
5775 <file>/usr/lib</file> directory, may install the shared library
5776 files in subdirectories of the <file>/usr/lib</file> directory,
5777 in which case they should arrange to add that directory in
5778 <file>/etc/ld.so.conf</file> in the package's post-installation
5779 script, and remove it in the package's post-removal script.
5783 An ever increasing number of packages are using
5784 <prgn>libtool</prgn> to do their linking. The latest GNU
5785 libtools (>= 1.3a) can take advantage of the metadata in the
5786 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
5787 files). The main advantage of <prgn>libtool</prgn>'s
5788 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
5789 store and subsequently access metadata with respect to the
5790 libraries it builds. <prgn>libtool</prgn> will search for
5791 those files, which contain a lot of useful information about
5792 a library (such as library dependency information for static
5793 linking). Also, they're <em>essential</em> for programs
5794 using <tt>libltdl</tt>.<footnote>
5795 Although <prgn>libtool</prgn> is fully capable of
5796 linking against shared libraries which don't have
5797 <tt>.la</tt> files, as it is a mere shell script it can
5798 add considerably to the build time of a
5799 <prgn>libtool</prgn>-using package if that shell script
5800 has to derive all this information from first principles
5801 for each library every time it is linked. With the
5802 advent of <prgn>libtool</prgn> version 1.4 (and to a
5803 lesser extent <prgn>libtool</prgn> version 1.3), the
5804 <file>.la</file> files also store information about
5805 inter-library dependencies which cannot necessarily be
5806 derived after the <file>.la</file> file is deleted.
5811 Packages that use <prgn>libtool</prgn> to create shared
5812 libraries should include the <file>.la</file> files in the
5813 <tt>-dev</tt> package, unless the package relies on
5814 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
5815 the <tt>.la</tt> files must go in the run-time library
5820 You must make sure that you use only released versions of
5821 shared libraries to build your packages; otherwise other
5822 users will not be able to run your binaries
5823 properly. Producing source packages that depend on
5824 unreleased compilers is also usually a bad
5831 <heading>Shared libraries</heading>
5833 This section has moved to <ref id="sharedlibs">.
5839 <heading>Scripts</heading>
5842 All command scripts, including the package maintainer
5843 scripts inside the package and used by <prgn>dpkg</prgn>,
5844 should have a <tt>#!</tt> line naming the shell to be used
5849 In the case of Perl scripts this should be
5850 <tt>#!/usr/bin/perl</tt>.
5854 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
5855 should almost certainly start with <tt>set -e</tt> so that
5856 errors are detected. Every script should use
5857 <tt>set -e</tt> or check the exit status of <em>every</em>
5862 The standard shell interpreter <file>/bin/sh</file> can be a
5863 symbolic link to any POSIX compatible shell, if <tt>echo
5864 -n</tt> does not generate a newline.<footnote>
5865 Debian policy specifies POSIX behavior for
5866 <file>/bin/sh</file>, but <tt>echo -n</tt> has widespread
5867 use in the Linux community (in particular including this
5868 policy, the Linux kernel source, many Debian scripts,
5869 etc.). This <tt>echo -n</tt> mechanism is valid but not
5870 required under POSIX, hence this explicit addition.
5871 Also, rumour has it that this shall be mandated under
5874 Thus, shell scripts specifying <file>/bin/sh</file> as
5875 interpreter should only use POSIX features. If a script
5876 requires non-POSIX features from the shell interpreter, the
5877 appropriate shell must be specified in the first line of the
5878 script (e.g., <tt>#!/bin/bash</tt>) and the package must
5879 depend on the package providing the shell (unless the shell
5880 package is marked "Essential", as in the case of
5885 You may wish to restrict your script to POSIX features when
5886 possible so that it may use <file>/bin/sh</file> as its
5887 interpreter. If your script works with <prgn>dash</prgn>
5888 (originally called <prgn>ash</prgn>), it's probably POSIX
5889 compliant, but if you are in doubt, use
5890 <file>/bin/bash</file>.
5894 Perl scripts should check for errors when making any
5895 system calls, including <tt>open</tt>, <tt>print</tt>,
5896 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
5900 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
5901 scripting languages. See <em>Csh Programming Considered
5902 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
5903 can be found at <url id="http://language.perl.com/versus/csh.whynot">.
5904 If an upstream package comes with <prgn>csh</prgn> scripts
5905 then you must make sure that they start with
5906 <tt>#!/bin/csh</tt> and make your package depend on the
5907 <prgn>c-shell</prgn> virtual package.
5911 Any scripts which create files in world-writeable
5912 directories (e.g., in <file>/tmp</file>) must use a
5913 mechanism which will fail if a file with the same name
5918 The Debian base system provides the <prgn>tempfile</prgn>
5919 and <prgn>mktemp</prgn> utilities for use by scripts for
5926 <heading>Symbolic links</heading>
5929 In general, symbolic links within a top-level directory
5930 should be relative, and symbolic links pointing from one
5931 top-level directory into another should be absolute. (A
5932 top-level directory is a sub-directory of the root
5933 directory <file>/</file>.)
5937 In addition, symbolic links should be specified as short as
5938 possible, i.e., link targets like <file>foo/../bar</file> are
5943 Note that when creating a relative link using
5944 <prgn>ln</prgn> it is not necessary for the target of the
5945 link to exist relative to the working directory you're
5946 running <prgn>ln</prgn> from, nor is it necessary to change
5947 directory to the directory where the link is to be made.
5948 Simply include the string that should appear as the target
5949 of the link (this will be a pathname relative to the
5950 directory in which the link resides) as the first argument
5955 For example, in your <prgn>Makefile</prgn> or
5956 <file>debian/rules</file>, you can do things like:
5957 <example compact="compact">
5958 ln -fs gcc $(prefix)/bin/cc
5959 ln -fs gcc debian/tmp/usr/bin/cc
5960 ln -fs ../sbin/sendmail $(prefix)/bin/runq
5961 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
5966 A symbolic link pointing to a compressed file should always
5967 have the same file extension as the referenced file. (For
5968 example, if a file <file>foo.gz</file> is referenced by a
5969 symbolic link, the filename of the link has to end with
5970 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
5975 <heading>Device files</heading>
5978 Packages must not include device files in the package file
5983 If a package needs any special device files that are not
5984 included in the base system, it must call
5985 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
5986 after notifying the user<footnote>
5987 This notification could be done via a (low-priority)
5988 debconf message, or an echo (printf) statement.
5993 Packages must not remove any device files in the
5994 <prgn>postrm</prgn> or any other script. This is left to the
5995 system administrator.
5999 Debian uses the serial devices
6000 <file>/dev/ttyS*</file>. Programs using the old
6001 <file>/dev/cu*</file> devices should be changed to use
6002 <file>/dev/ttyS*</file>.
6006 <sect id="config-files">
6007 <heading>Configuration files</heading>
6010 <heading>Definitions</heading>
6014 <tag>configuration file</tag>
6016 A file that affects the operation of a program, or
6017 provides site- or host-specific information, or
6018 otherwise customizes the behavior of a program.
6019 Typically, configuration files are intended to be
6020 modified by the system administrator (if needed or
6021 desired) to conform to local policy or to provide
6022 more useful site-specific behavior.
6025 <tag><tt>conffile</tt></tag>
6027 A file listed in a package's <tt>conffiles</tt>
6028 file, and is treated specially by <prgn>dpkg</prgn>
6029 (see <ref id="configdetails">).
6035 The distinction between these two is important; they are
6036 not interchangeable concepts. Almost all
6037 <tt>conffile</tt>s are configuration files, but many
6038 configuration files are not <tt>conffiles</tt>.
6042 Note that a script that embeds configuration information
6043 (such as most of the files in <file>/etc/default</file> and
6044 <file>/etc/cron.{daily,weekly,monthly}</file>) is de-facto a
6045 configuration file and should be treated as such.
6050 <heading>Location</heading>
6053 Any configuration files created or used by your package
6054 must reside in <file>/etc</file>. If there are several,
6055 consider creating a subdirectory of <file>/etc</file>
6056 named after your package.
6060 If your package creates or uses configuration files
6061 outside of <file>/etc</file>, and it is not feasible to modify
6062 the package to use <file>/etc</file> directly, put the files
6063 in <file>/etc</file> and create symbolic links to those files
6064 from the location that the package requires.
6069 <heading>Behavior</heading>
6072 Configuration file handling must conform to the following
6074 <list compact="compact">
6076 local changes must be preserved during a package
6080 configuration files must be preserved when the
6081 package is removed, and only deleted when the
6088 The easy way to achieve this behavior is to make the
6089 configuration file a <tt>conffile</tt>. This is
6090 appropriate only if it is possible to distribute a default
6091 version that will work for most installations, although
6092 some system administrators may choose to modify it. This
6093 implies that the default version will be part of the
6094 package distribution, and must not be modified by the
6095 maintainer scripts during installation (or at any other
6100 In order to ensure that local changes are preserved
6101 correctly, no package may contain or make hard links to
6102 conffiles.<footnote>
6103 Rationale: There are two problems with hard links.
6104 The first is that some editors break the link while
6105 editing one of the files, so that the two files may
6106 unwittingly become unlinked and different. The second
6107 is that <prgn>dpkg</prgn> might break the hard link
6108 while upgrading <tt>conffile</tt>s.
6113 The other way to do it is via the maintainer scripts. In
6114 this case, the configuration file must not be listed as a
6115 <tt>conffile</tt> and must not be part of the package
6116 distribution. If the existence of a file is required for
6117 the package to be sensibly configured it is the
6118 responsibility of the package maintainer to provide
6119 maintainer scripts which correctly create, update and
6120 maintain the file and remove it on purge. (See <ref
6121 id="maintainerscripts"> for more information.) These
6122 scripts must be idempotent (i.e., must work correctly if
6123 <prgn>dpkg</prgn> needs to re-run them due to errors
6124 during installation or removal), must cope with all the
6125 variety of ways <prgn>dpkg</prgn> can call maintainer
6126 scripts, must not overwrite or otherwise mangle the user's
6127 configuration without asking, must not ask unnecessary
6128 questions (particularly during upgrades), and otherwise be
6133 The scripts are not required to configure every possible
6134 option for the package, but only those necessary to get
6135 the package running on a given system. Ideally the
6136 sysadmin should not have to do any configuration other
6137 than that done (semi-)automatically by the
6138 <prgn>postinst</prgn> script.
6142 A common practice is to create a script called
6143 <file><var>package</var>-configure</file> and have the
6144 package's <prgn>postinst</prgn> call it if and only if the
6145 configuration file does not already exist. In certain
6146 cases it is useful for there to be an example or template
6147 file which the maintainer scripts use. Such files should
6148 be in <file>/usr/share/<var>package</var></file> or
6149 <file>/usr/lib/<var>package</var></file> (depending on whether
6150 they are architecture-independent or not). There should
6151 be symbolic links to them from
6152 <file>/usr/share/doc/<var>package</var>/examples</file> if
6153 they are examples, and should be perfectly ordinary
6154 <prgn>dpkg</prgn>-handled files (<em>not</em>
6155 configuration files).
6159 These two styles of configuration file handling must
6160 not be mixed, for that way lies madness:
6161 <prgn>dpkg</prgn> will ask about overwriting the file
6162 every time the package is upgraded.
6167 <heading>Sharing configuration files</heading>
6170 Packages which specify the same file as a
6171 <tt>conffile</tt> must be tagged as <em>conflicting</em>
6172 with each other. (This is an instance of the general rule
6173 about not sharing files. Note that neither alternatives
6174 nor diversions are likely to be appropriate in this case;
6175 in particular, <prgn>dpkg</prgn> does not handle diverted
6176 <tt>conffile</tt>s well.)
6180 The maintainer scripts must not alter a <tt>conffile</tt>
6181 of <em>any</em> package, including the one the scripts
6186 If two or more packages use the same configuration file
6187 and it is reasonable for both to be installed at the same
6188 time, one of these packages must be defined as
6189 <em>owner</em> of the configuration file, i.e., it will be
6190 the package which handles that file as a configuration
6191 file. Other packages that use the configuration file must
6192 depend on the owning package if they require the
6193 configuration file to operate. If the other package will
6194 use the configuration file if present, but is capable of
6195 operating without it, no dependency need be declared.
6199 If it is desirable for two or more related packages to
6200 share a configuration file <em>and</em> for all of the
6201 related packages to be able to modify that configuration
6202 file, then the following should be done:
6203 <enumlist compact="compact">
6205 One of the related packages (the "owning" package)
6206 will manage the configuration file with maintainer
6207 scripts as described in the previous section.
6210 The owning package should also provide a program
6211 that the other packages may use to modify the
6215 The related packages must use the provided program
6216 to make any desired modifications to the
6217 configuration file. They should either depend on
6218 the core package to guarantee that the configuration
6219 modifier program is available or accept gracefully
6220 that they cannot modify the configuration file if it
6221 is not. (This is in addition to the fact that the
6222 configuration file may not even be present in the
6229 Sometimes it's appropriate to create a new package which
6230 provides the basic infrastructure for the other packages
6231 and which manages the shared configuration files. (The
6232 <tt>sgml-base</tt> package is a good example.)
6237 <heading>User configuration files ("dotfiles")</heading>
6240 The files in <file>/etc/skel</file> will automatically be
6241 copied into new user accounts by <prgn>adduser</prgn>.
6242 No other program should reference the files in
6243 <file>/etc/skel</file>.
6247 Therefore, if a program needs a dotfile to exist in
6248 advance in <file>$HOME</file> to work sensibly, that dotfile
6249 should be installed in <file>/etc/skel</file> and treated as a
6254 However, programs that require dotfiles in order to
6255 operate sensibly are a bad thing, unless they do create
6256 the dotfiles themselves automatically.
6260 Furthermore, programs should be configured by the Debian
6261 default installation to behave as closely to the upstream
6262 default behaviour as possible.
6266 Therefore, if a program in a Debian package needs to be
6267 configured in some way in order to operate sensibly, that
6268 should be done using a site-wide configuration file placed
6269 in <file>/etc</file>. Only if the program doesn't support a
6270 site-wide default configuration and the package maintainer
6271 doesn't have time to add it may a default per-user file be
6272 placed in <file>/etc/skel</file>.
6276 <file>/etc/skel</file> should be as empty as we can make it.
6277 This is particularly true because there is no easy (or
6278 necessarily desirable) mechanism for ensuring that the
6279 appropriate dotfiles are copied into the accounts of
6280 existing users when a package is installed.
6286 <heading>Log files</heading>
6288 Log files should usually be named
6289 <file>/var/log/<var>package</var>.log</file>. If you have many
6290 log files, or need a separate directory for permission
6291 reasons (<file>/var/log</file> is writable only by
6292 <file>root</file>), you should usually create a directory named
6293 <file>/var/log/<var>package</var></file> and place your log
6298 Log files must be rotated occasionally so that they don't
6299 grow indefinitely; the best way to do this is to drop a log
6300 rotation configuration file into the directory
6301 <file>/etc/logrotate.d</file> and use the facilities provided by
6302 logrotate.<footnote>
6304 The traditional approach to log files has been to set up
6305 <em>ad hoc</em> log rotation schemes using simple shell
6306 scripts and cron. While this approach is highly
6307 customizable, it requires quite a lot of sysadmin work.
6308 Even though the original Debian system helped a little
6309 by automatically installing a system which can be used
6310 as a template, this was deemed not enough.
6314 The use of <prgn>logrotate</prgn>, a program developed
6315 by Red Hat, is better, as it centralizes log management.
6316 It has both a configuration file
6317 (<file>/etc/logrotate.conf</file>) and a directory where
6318 packages can drop their individual log rotation
6319 configurations (<file>/etc/logrotate.d</file>).
6322 Here is a good example for a logrotate config
6323 file (for more information see <manref name="logrotate"
6325 <example compact="compact">
6326 /var/log/foo/*.log {
6331 /etc/init.d/foo force-reload
6335 This rotates all files under <file>/var/log/foo</file>, saves 12
6336 compressed generations, and forces the daemon to reload its
6337 configuration information after the log rotation.
6341 Log files should be removed when the package is
6342 purged (but not when it is only removed). This should be
6343 done by the <prgn>postrm</prgn> script when it is called
6344 with the argument <tt>purge</tt> (see <ref
6345 id="removedetails">).
6350 <heading>Permissions and owners</heading>
6353 The rules in this section are guidelines for general use.
6354 If necessary you may deviate from the details below.
6355 However, if you do so you must make sure that what is done
6356 is secure and you should try to be as consistent as possible
6357 with the rest of the system. You should probably also
6358 discuss it on <prgn>debian-devel</prgn> first.
6362 Files should be owned by <tt>root.root</tt>, and made
6363 writable only by the owner and universally readable (and
6364 executable, if appropriate), that is mode 644 or 755.
6368 Directories should be mode 755 or (for group-writability)
6369 mode 2775. The ownership of the directory should be
6370 consistent with its mode: if a directory is mode 2775, it
6371 should be owned by the group that needs write access to
6376 Setuid and setgid executables should be mode 4755 or 2755
6377 respectively, and owned by the appropriate user or group.
6378 They should not be made unreadable (modes like 4711 or
6379 2711 or even 4111); doing so achieves no extra security,
6380 because anyone can find the binary in the freely available
6381 Debian package; it is merely inconvenient. For the same
6382 reason you should not restrict read or execute permissions
6383 on non-set-id executables.
6387 Some setuid programs need to be restricted to particular
6388 sets of users, using file permissions. In this case they
6389 should be owned by the uid to which they are set-id, and by
6390 the group which should be allowed to execute them. They
6391 should have mode 4754; again there is no point in making
6392 them unreadable to those users who must not be allowed to
6397 It is possible to arrange that the system administrator can
6398 reconfigure the package to correspond to their local
6399 security policy by changing the permissions on a binary:
6400 they can do this by using <prgn>dpkg-statoverride</prgn>, as
6401 described below.<footnote>
6402 Ordinary files installed by <prgn>dpkg</prgn> (as
6403 opposed to <tt>conffile</tt>s and other similar objects)
6404 normally have their permissions reset to the distributed
6405 permissions when the package is reinstalled. However,
6406 the use of <prgn>dpkg-statoverride</prgn> overrides this
6407 default behaviour. If you use this method, you should
6408 remember to describe <prgn>dpkg-statoverride</prgn> in
6409 the package documentation; being a relatively new
6410 addition to Debian, it is probably not yet well-known.
6412 Another method you should consider is to create a group for
6413 people allowed to use the program(s) and make any setuid
6414 executables executable only by that group.
6418 If you need to create a new user or group for your package
6419 there are two possibilities. Firstly, you may need to
6420 make some files in the binary package be owned by this
6421 user or group, or you may need to compile the user or
6422 group id (rather than just the name) into the binary
6423 (though this latter should be avoided if possible, as in
6424 this case you need a statically allocated id).</p>
6427 If you need a statically allocated id, you must ask for a
6428 user or group id from the <tt>base-passwd</tt> maintainer,
6429 and must not release the package until you have been
6430 allocated one. Once you have been allocated one you must
6431 either make the package depend on a version of the
6432 <tt>base-passwd</tt> package with the id present in
6433 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
6434 your package to create the user or group itself with the
6435 correct id (using <tt>adduser</tt>) in its
6436 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
6437 the <prgn>postinst</prgn> is to be preferred if it is
6438 possible, otherwise a pre-dependency will be needed on the
6439 <tt>adduser</tt> package.)
6443 On the other hand, the program might be able to determine
6444 the uid or gid from the user or group name at runtime, so
6445 that a dynamically allocated id can be used. In this case
6446 you should choose an appropriate user or group name,
6447 discussing this on <prgn>debian-devel</prgn> and checking
6448 with the <package/base-passwd/ maintainer that it is unique and that
6449 they do not wish you to use a statically allocated id
6450 instead. When this has been checked you must arrange for
6451 your package to create the user or group if necessary using
6452 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
6453 <prgn>postinst</prgn> script (again, the latter is to be
6454 preferred if it is possible).
6458 Note that changing the numeric value of an id associated
6459 with a name is very difficult, and involves searching the
6460 file system for all appropriate files. You need to think
6461 carefully whether a static or dynamic id is required, since
6462 changing your mind later will cause problems.
6465 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
6467 This section is not intended as policy, but as a
6468 description of the use of <prgn>dpkg-statoverride</prgn>.
6472 <prgn>dpkg-statoverride</prgn> is a replacement for the
6473 deprecated <tt>suidmanager</tt> package. Packages which
6474 previously used <tt>suidmanager</tt> should have a
6475 <tt>Conflicts: suidmanager (<< 0.50)</tt> entry (or even
6476 <tt>(<< 0.52)</tt>), and calls to <tt>suidregister</tt>
6477 and <tt>suidunregister</tt> should now be simply removed
6478 from the maintainer scripts.
6482 If a system administrator wishes to have a file (or
6483 directory or other such thing) installed with owner and
6484 permissions different from those in the distributed Debian
6485 package, he can use the <prgn>dpkg-statoverride</prgn>
6486 program to instruct <prgn>dpkg</prgn> to use the different
6487 settings every time the file is installed. Thus the
6488 package maintainer should distribute the files with their
6489 normal permissions, and leave it for the system
6490 administrator to make any desired changes. For example, a
6491 daemon which is normally required to be setuid root, but
6492 in certain situations could be used without being setuid,
6493 should be installed setuid in the <tt>.deb</tt>. Then the
6494 local system administrator can change this if they wish.
6495 If there are two standard ways of doing it, the package
6496 maintainer can use <tt>debconf</tt> to find out the
6497 preference, and call <prgn>dpkg-statoverride</prgn> in the
6498 maintainer script if necessary to accommodate the system
6499 administrator's choice.
6503 Given the above, <prgn>dpkg-statoverride</prgn> is
6504 essentially a tool for system administrators and would not
6505 normally be needed in the maintainer scripts. There is
6506 one type of situation, though, where calls to
6507 <prgn>dpkg-statoverride</prgn> would be needed in the
6508 maintainer scripts, and that involves packages which use
6509 dynamically allocated user or group ids. In such a
6510 situation, something like the following idiom can be very
6511 helpful in the package's <prgn>postinst</prgn>, where
6512 <tt>sysuser</tt> is a dynamically allocated id:
6514 for i in /usr/bin/foo /usr/sbin/bar
6516 if ! dpkg-statoverride --list $i >/dev/null
6518 dpkg-statoverride --update --add sysuser root 4755 $i
6522 The corresponding <tt>dpkg-statoverride --remove</tt>
6523 calls can then be made unconditionally when the package is
6530 <chapt id="customized-programs">
6531 <heading>Customized programs</heading>
6533 <sect id="arch-spec">
6534 <heading>Architecture specification strings</heading>
6537 If a program needs to specify an <em>architecture specification
6538 string</em> in some place, the following format should be
6539 used: <var>arch</var>-<var>os</var><footnote>
6540 The following architectures and operating systems are
6541 currently recognised by <prgn>dpkg-archictecture</prgn>.
6542 The architecture, <tt><var>arch</var></tt>, is one of
6543 the following: <tt>alpha</tt>, <tt>arm</tt>,
6544 <tt>hppa</tt>, <tt>i386</tt>, <tt>ia64</tt>,
6545 <tt>m68k</tt>, <tt>mips</tt>, <tt>mipsel</tt>,
6546 <tt>powerpc</tt>, <tt>s390</tt>, <tt>sh</tt>,
6547 <tt>sheb</tt>, <tt>sparc</tt> and <tt>sparc64</tt>. The
6548 operating system, <tt><var>os</var></tt>, is one of:
6549 <tt>linux</tt>, <tt>gnu</tt>, <tt>freebsd</tt> and
6550 <tt>openbsd</tt>. Use of <tt>gnu</tt> in this string is
6551 reserved for the GNU/Hurd operating system.
6556 Note that we don't want to use
6557 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
6558 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
6559 since this would make our programs incompatible with other
6560 Linux distributions. We also don't use something like
6561 <tt><var>arch</var>-unknown-linux</tt>, since the
6562 <tt>unknown</tt> does not look very good.
6567 <heading>Daemons</heading>
6570 The configuration files <file>/etc/services</file>,
6571 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
6572 by the <prgn>netbase</prgn> package and must not be modified
6577 If a package requires a new entry in one of these files, the
6578 maintainer should get in contact with the
6579 <prgn>netbase</prgn> maintainer, who will add the entries
6580 and release a new version of the <prgn>netbase</prgn>
6585 The configuration file <file>/etc/inetd.conf</file> must not be
6586 modified by the package's scripts except via the
6587 <prgn>update-inetd</prgn> script or the
6588 <file>DebianNet.pm</file> Perl module. See their documentation
6589 for details on how to add entries.
6593 If a package wants to install an example entry into
6594 <file>/etc/inetd.conf</file>, the entry must be preceded with
6595 exactly one hash character (<tt>#</tt>). Such lines are
6596 treated as "commented out by user" by the
6597 <prgn>update-inetd</prgn> script and are not changed or
6598 activated during package updates.
6603 <heading>Using pseudo-ttys and modifying wtmp, utmp and
6607 Some programs need to create pseudo-ttys. This should be done
6608 using Unix98 ptys if the C library supports it. The resulting
6609 program must not be installed setuid root, unless that
6610 is required for other functionality.
6614 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
6615 <file>/var/log/lastlog</file> must be installed writeable by
6616 group <tt>utmp</tt>. Programs which need to modify those
6617 files must be installed setgid <tt>utmp</tt>.
6622 <heading>Editors and pagers</heading>
6625 Some programs have the ability to launch an editor or pager
6626 program to edit or display a text document. Since there are
6627 lots of different editors and pagers available in the Debian
6628 distribution, the system administrator and each user should
6629 have the possibility to choose his/her preferred editor and
6634 In addition, every program should choose a good default
6635 editor/pager if none is selected by the user or system
6640 Thus, every program that launches an editor or pager must
6641 use the EDITOR or PAGER environment variable to determine
6642 the editor or pager the user wishes to use. If these
6643 variables are not set, the programs <file>/usr/bin/editor</file>
6644 and <file>/usr/bin/pager</file> should be used, respectively.
6648 These two files are managed through the <prgn>dpkg</prgn>
6649 "alternatives" mechanism. Thus every package providing an
6650 editor or pager must call the
6651 <prgn>update-alternatives</prgn> script to register these
6656 If it is very hard to adapt a program to make use of the
6657 EDITOR or PAGER variables, that program may be configured to
6658 use <file>/usr/bin/sensible-editor</file> and
6659 <file>/usr/bin/sensible-pager</file> as the editor or pager
6660 program respectively. These are two scripts provided in the
6661 Debian base system that check the EDITOR and PAGER variables
6662 and launch the appropriate program, and fall back to
6663 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
6664 variable is not set.
6668 A program may also use the VISUAL environment variable to
6669 determine the user's choice of editor. If it exists, it
6670 should take precedence over EDITOR. This is in fact what
6671 <file>/usr/bin/sensible-editor</file> does.
6675 It is not required for a package to depend on
6676 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
6677 package to provide such virtual packages.<footnote>
6678 The Debian base system already provides an editor and a
6684 <sect id="web-appl">
6685 <heading>Web servers and applications</heading>
6688 This section describes the locations and URLs that should
6689 be used by all web servers and web applications in the
6696 Cgi-bin executable files are installed in the
6698 <example compact="compact">
6699 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
6701 and should be referred to as
6702 <example compact="compact">
6703 http://localhost/cgi-bin/<var>cgi-bin-name</var>
6708 <p>Access to HTML documents</p>
6711 HTML documents for a package are stored in
6712 <file>/usr/share/doc/<var>package</var></file>
6713 and can be referred to as
6714 <example compact="compact">
6715 http://localhost/doc/<var>package</var>/<var>filename</var>
6720 The web server should restrict access to the document
6721 tree so that only clients on the same host can read
6722 the documents. If the web server does not support such
6723 access controls, then it should not provide access at
6724 all, or ask about providing access during installation.
6729 <p>Web Document Root</p>
6732 Web Applications should try to avoid storing files in
6733 the Web Document Root. Instead they should use the
6734 /usr/share/doc/<var>package</var> directory for
6735 documents and register the Web Application via the
6736 menu package. If access to the web document root is
6737 unavoidable then use
6738 <example compact="compact">
6741 as the Document Root. This might be just a symbolic
6742 link to the location where the system administrator
6743 has put the real document root.
6751 <sect id="mail-transport-agents">
6752 <heading>Mail transport, delivery and user agents</heading>
6755 Debian packages which process electronic mail, whether mail
6756 user agents (MUAs) or mail transport agents (MTAs), must
6757 ensure that they are compatible with the configuration
6758 decisions below. Failure to do this may result in lost
6759 mail, broken <tt>From:</tt> lines, and other serious brain
6764 The mail spool is <file>/var/mail</file> and the interface to
6765 send a mail message is <file>/usr/sbin/sendmail</file> (as per
6766 the FHS). On older systems, the mail spool may be
6767 physically located in <file>/var/spool/mail</file>, but all
6768 access to the mail spool should be via the
6769 <file>/var/mail</file> symlink. The mail spool is part of the
6770 base system and not part of the MTA package.
6774 All Debian MUAs, MTAs, MDAs and other mailbox accessing
6775 programs (such as IMAP daemons) must lock the mailbox in an
6776 NFS-safe way. This means that <tt>fcntl()</tt> locking must
6777 be combined with dot locking. To avoid deadlocks, a program
6778 should use <tt>fcntl()</tt> first and dot locking after
6779 this, or alternatively implement the two locking methods in
6780 a non blocking way<footnote>
6781 If it is not possible to establish both locks, the
6782 system shouldn't wait for the second lock to be
6783 established, but remove the first lock, wait a (random)
6784 time, and start over locking again.
6785 </footnote>. Using the functions <tt>maillock</tt> and
6786 <tt>mailunlock</tt> provided by the
6787 <tt>liblockfile*</tt><footnote>
6789 You will need to depend on <tt>liblockfile1
6790 (>>1.01)</tt> to use these functions.
6792 </footnote> packages is the recommended way to realize this.
6796 Mailboxes are generally mode 660
6797 <tt><var>user</var>.mail</tt> unless the system
6798 administrator has chosen otherwise. A MUA may remove a
6799 mailbox (unless it has nonstandard permissions) in which
6800 case the MTA or another MUA must recreate it if needed.
6801 Mailboxes must be writable by group mail.
6805 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
6806 be setgid mail to do the locking mentioned above (and
6807 must obviously avoid accessing other users' mailboxes
6808 using this privilege).</p>
6811 <file>/etc/aliases</file> is the source file for the system mail
6812 aliases (e.g., postmaster, usenet, etc.), it is the one
6813 which the sysadmin and <prgn>postinst</prgn> scripts may
6814 edit. After <file>/etc/aliases</file> is edited the program or
6815 human editing it must call <prgn>newaliases</prgn>. All MTA
6816 packages must come with a <prgn>newaliases</prgn> program,
6817 even if it does nothing, but older MTA packages did not do
6818 this so programs should not fail if <prgn>newaliases</prgn>
6819 cannot be found. Note that because of this, all MTA
6820 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
6821 <tt>Replaces: mail-transport-agent</tt> control file
6826 The convention of writing <tt>forward to
6827 <var>address</var></tt> in the mailbox itself is not
6828 supported. Use a <tt>.forward</tt> file instead.</p>
6831 The <prgn>rmail</prgn> program used by UUCP
6832 for incoming mail should be <file>/usr/sbin/rmail</file>.
6833 Likewise, <prgn>rsmtp</prgn>, for receiving
6834 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
6838 If your package needs to know what hostname to use on (for
6839 example) outgoing news and mail messages which are generated
6840 locally, you should use the file <file>/etc/mailname</file>. It
6841 will contain the portion after the username and <tt>@</tt>
6842 (at) sign for email addresses of users on the machine
6843 (followed by a newline).
6847 Such package should check for the existence of this file
6848 when it is being configured. If it exists, it should be
6849 used without comment, although an MTA's configuration script
6850 may wish to prompt the user even if it finds that this file
6851 exists. If the file does not exist, the package should
6852 prompt the user for the value (preferably using
6853 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
6854 as well as using it in the package's configuration. The
6855 prompt should make it clear that the name will not just be
6856 used by that package. For example, in this situation the
6857 <tt>inn</tt> package could say something like:
6858 <example compact="compact">
6859 Please enter the "mail name" of your system. This is the
6860 hostname portion of the address to be shown on outgoing
6861 news and mail messages. The default is
6862 <var>syshostname</var>, your system's host name. Mail
6863 name ["<var>syshostname</var>"]:
6865 where <var>syshostname</var> is the output of <tt>hostname
6871 <heading>News system configuration</heading>
6874 All the configuration files related to the NNTP (news)
6875 servers and clients should be located under
6876 <file>/etc/news</file>.</p>
6879 There are some configuration issues that apply to a number
6880 of news clients and server packages on the machine. These
6884 <tag><file>/etc/news/organization</file></tag>
6886 A string which should appear as the
6887 organization header for all messages posted
6888 by NNTP clients on the machine
6891 <tag><file>/etc/news/server</file></tag>
6893 Contains the FQDN of the upstream NNTP
6894 server, or localhost if the local machine is
6899 Other global files may be added as required for cross-package news
6906 <heading>Programs for the X Window System</heading>
6909 <heading>Providing X support and package priorities</heading>
6912 Programs that can be configured with support for the X
6913 Window System must be configured to do so and must declare
6914 any package dependencies necessary to satisfy their
6915 runtime requirements when using the X Window System. If
6916 such a package is of higher priority than the X packages
6917 on which it depends, it is required that either the
6918 X-specific components be split into a separate package, or
6919 that an alternative version of the package, which includes
6920 X support, be provided, or that the package's priority be
6926 <heading>Packages providing an X server</heading>
6929 Packages that provide an X server that, directly or
6930 indirectly, communicates with real input and display
6931 hardware should declare in their control data that they
6932 provide the virtual package <tt>xserver</tt>.<footnote>
6933 This implements current practice, and provides an
6934 actual policy for usage of the <tt>xserver</tt>
6935 virtual package which appears in the virtual packages
6936 list. In a nutshell, X servers that interface
6937 directly with the display and input hardware or via
6938 another subsystem (e.g., GGI) should provide
6939 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
6940 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
6946 <heading>Packages providing a terminal emulator</heading>
6949 Packages that provide a terminal emulator for the X Window
6950 System which meet the criteria listed below should declare
6951 in their control data that they provide the virtual
6952 package <tt>x-terminal-emulator</tt>. They should also
6953 register themselves as an alternative for
6954 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
6959 To be an <tt>x-terminal-emulator</tt>, a program must:
6960 <list compact="compact">
6962 Be able to emulate a DEC VT100 terminal, or a
6963 compatible terminal.
6967 Support the command-line option <tt>-e
6968 <var>command</var></tt>, which creates a new
6969 terminal window<footnote>
6970 "New terminal window" does not necessarily mean
6971 a new top-level X window directly parented by
6972 the window manager; it could, if the terminal
6973 emulator application were so coded, be a new
6974 "view" in a multiple-document interface (MDI).
6976 and runs the specified <var>command</var>,
6977 interpreting the entirity of the rest of the command
6978 line as a command to pass straight to exec, in the
6979 manner that <tt>xterm</tt> does.
6983 Support the command-line option <tt>-T
6984 <var>title</var></tt>, which creates a new terminal
6985 window with the window title <var>title</var>.
6992 <heading>Packages providing a window manager</heading>
6995 Packages that provide a window manager should declare in
6996 their control data that they provide the virtual package
6997 <tt>x-window-manager</tt>. They should also register
6998 themselves as an alternative for
6999 <file>/usr/bin/x-window-manager</file>, with a priority
7000 calculated as follows:
7001 <list compact="compact">
7003 Start with a priority of 20.
7007 If the window manager supports the Debian menu
7008 system, add 20 points if this support is available
7009 in the package's default configuration (i.e., no
7010 configuration files belonging to the system or user
7011 have to be edited to activate the feature); if
7012 configuration files must be modified, add only 10
7017 If the window manager complies with <url
7018 id="http://www.freedesktop.org/standards/wm-spec.html"
7019 name="The Window Manager Specification Project">,
7020 written by the <url id="http://www.freedesktop.org"
7021 name="Free Desktop Group">, add 40 points.
7025 If the window manager permits the X session to be
7026 restarted using a <em>different</em> window manager
7027 (without killing the X server) in its default
7028 configuration, add 10 points; otherwise add none.
7035 <heading>Packages providing fonts</heading>
7038 Packages that provide fonts for the X Window
7040 For the purposes of Debian Policy, a "font for the X
7041 Window System" is one which is accessed via X protocol
7042 requests. Fonts for the Linux console, for PostScript
7043 renderers, or any other purpose, do not fit this
7044 definition. Any tool which makes such fonts available
7045 to the X Window System, however, must abide by this
7048 must do a number of things to ensure that they are both
7049 available without modification of the X or font server
7050 configuration, and that they do not corrupt files used by
7051 other font packages to register information about
7055 Fonts of any type supported by the X Window System
7056 must be in a separate binary package from any
7057 executables, libraries, or documentation (except
7058 that specific to the fonts shipped, such as their
7059 license information). If one or more of the fonts
7060 so packaged are necessary for proper operation of
7061 the package with which they are associated the font
7062 package may be Recommended; if the fonts merely
7063 provide an enhancement, a Suggests relationship may
7064 be used. Packages must not Depend on font
7066 This is because the X server may retrieve fonts
7067 from the local filesystem or over the network
7068 from an X font server; the Debian package system
7069 is empowered to deal only with the local
7075 BDF fonts must be converted to PCF fonts with the
7076 <prgn>bdftopcf</prgn> utility (available in the
7077 <tt>xutils</tt> package, <prgn>gzip</prgn>ped, and
7078 placed in a directory that corresponds to their
7080 <list compact="compact">
7082 100 dpi fonts must be placed in
7083 <file>/usr/X11R6/lib/X11/fonts/100dpi/</file>.
7087 75 dpi fonts must be placed in
7088 <file>/usr/X11R6/lib/X11/fonts/75dpi/</file>.
7092 Character-cell fonts, cursor fonts, and other
7093 low-resolution fonts must be placed in
7094 <file>/usr/X11R6/lib/X11/fonts/misc/</file>.
7100 Speedo fonts must be placed in
7101 <file>/usr/X11R6/lib/X11/fonts/Speedo/</file>.
7105 Type 1 fonts must be placed in
7106 <file>/usr/X11R6/lib/X11/fonts/Type1/</file>. If font
7107 metric files are available, they must be placed here
7112 Subdirectories of <file>/usr/X11R6/lib/X11/fonts/</file>
7113 other than those listed above must be neither
7114 created nor used. (The <file>PEX</file>, <file>CID</file>,
7115 and <file>cyrillic</file> directories are excepted for
7116 historical reasons, but installation of files into
7117 these directories remains discouraged.)
7121 Font packages may, instead of placing files directly
7122 in the X font directories listed above, provide
7123 symbolic links in that font directory pointing to
7124 the files' actual location in the filesystem. Such
7125 a location must comply with the FHS.
7129 Font packages should not contain both 75dpi and
7130 100dpi versions of a font. If both are available,
7131 they should be provided in separate binary packages
7132 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
7133 the names of the packages containing the
7134 corresponding fonts.
7138 Fonts destined for the <file>misc</file> subdirectory
7139 should not be included in the same package as 75dpi
7140 or 100dpi fonts; instead, they should be provided in
7141 a separate package with <tt>-misc</tt> appended to
7146 Font packages must not provide the files
7147 <file>fonts.dir</file>, <file>fonts.alias</file>, or
7148 <file>fonts.scale</file> in a font directory:
7151 <file>fonts.dir</file> files must not be provided at all.
7155 <file>fonts.alias</file> and <file>fonts.scale</file>
7156 files, if needed, should be provided in the
7158 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
7159 where <var>fontdir</var> is the name of the
7161 <file>/usr/X11R6/lib/X11/fonts/</file> where the
7162 package's corresponding fonts are stored
7163 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
7164 <var>package</var> is the name of the package
7165 that provides these fonts, and
7166 <var>extension</var> is either <tt>scale</tt>
7167 or <tt>alias</tt>, whichever corresponds to
7174 Font packages must declare a dependency on
7175 <tt>xutils (>> 4.0.3)</tt> in their control
7180 Font packages that provide one or more
7181 <file>fonts.scale</file> files as described above must
7182 invoke <prgn>update-fonts-scale</prgn> on each
7183 directory into which they installed fonts
7184 <em>before</em> invoking
7185 <prgn>update-fonts-dir</prgn> on that directory.
7186 This invocation must occur in both the
7187 <prgn>postinst</prgn> (for all arguments) and
7188 <prgn>postrm</prgn> (for all arguments except
7189 <tt>upgrade</tt>) scripts.
7193 Font packages that provide one or more
7194 <file>fonts.alias</file> files as described above must
7195 invoke <prgn>update-fonts-alias</prgn> on each
7196 directory into which they installed fonts. This
7197 invocation must occur in both the
7198 <prgn>postinst</prgn> (for all arguments) and
7199 <prgn>postrm</prgn> (for all arguments except
7200 <tt>upgrade</tt>) scripts.
7204 Font packages must invoke
7205 <prgn>update-fonts-dir</prgn> on each directory into
7206 which they installed fonts. This invocation must
7207 occur in both the <prgn>postinst</prgn> (for all
7208 arguments) and <prgn>postrm</prgn> (for all
7209 arguments except <tt>upgrade</tt>) scripts.
7213 Font packages must not provide alias names for the
7214 fonts they include which collide with alias names
7215 already in use by fonts already packaged.
7219 Font packages must not provide fonts with the same
7220 XLFD registry name as another font already packaged.
7227 <heading>Application defaults files</heading>
7230 Application defaults files must be installed in the
7231 directory <file>/etc/X11/app-defaults/</file> (use of a
7232 localized subdirectory of <file>/etc/X11/</file> as described
7233 in the <em>X Toolkit Intrinsics - C Language
7234 Interface</em> manual is also permitted). They must be
7235 registered as <tt>conffile</tt>s or handled as
7236 configuration files. Packages must not provide the
7237 directory <file>/usr/X11R6/lib/X11/app-defaults/</file>.
7241 Customization of programs' X resources may also be
7242 supported with the provision of a file with the same name
7243 as that of the package placed in the
7244 <file>/etc/X11/Xresources/</file> directory, which must
7245 registered as a <tt>conffile</tt> or handled as a
7246 configuration file.<footnote>
7247 Note that this mechanism is not the same as using
7248 app-defaults; app-defaults are tied to the client
7249 binary on the local filesystem, whereas X resources
7250 are stored in the X server and affect all connecting
7253 <em>Important:</em> packages that install files into the
7254 <file>/etc/X11/Xresources/</file> directory must conflict with
7255 <tt>xbase (<< 3.3.2.3a-2)</tt>; if this is not done
7256 it is possible for the installing package to destroy a
7257 previously-existing <file>/etc/X11/Xresources</file> file
7258 which had been customized by the system administrator.
7263 <heading>Installation directory issues</heading>
7266 Packages using the X Window System should not be
7267 configured to install files under the <file>/usr/X11R6/</file>
7268 directory unless they use <prgn>imake</prgn>. The
7269 <file>/usr/X11R6/</file> directory hierarchy should be
7270 regarded as deprecated for all packages except the X
7271 Window System itself, and those which use the
7272 <prgn>imake</prgn> program it provides, in which case the
7273 packages may transition out of the <file>/usr/X11R6/</file>
7274 directory at the maintainer's discretion.<footnote>
7275 <prgn>Imake</prgn>-using programs are exempt because,
7276 as long as they are written correctly, the pathnames
7277 they use to locate resources and install themselves
7278 are derived wholly from the X Window System
7279 configuration. Thus, in the event that the X Window
7280 System moves to <file>/usr/X11R7/</file>,
7281 <file>/usr/X12/</file>, or just plain <file>/usr/</file>, all
7282 that is required for these programs is a recompile
7283 against the corresponding X Window System library
7284 development packages.
7289 Programs that use GNU <prgn>autoconf</prgn> and
7290 <prgn>automake</prgn> are usually easily configured at
7291 compile time to use <file>/usr/</file> instead of
7292 <file>/usr/X11R6/</file>, and this should be done whenever
7293 possible. Configuration files for window managers and
7294 display managers should be placed in a subdirectory of
7295 <file>/etc/X11/</file> corresponding to the package name due
7296 to these programs' tight integration with the mechanisms
7297 of the X Window System. Application-level programs should
7298 use the <file>/etc/</file> directory unless otherwise mandated
7303 The installation of files into subdirectories
7304 of <file>/usr/X11R6/include/X11/</file> and
7305 <file>/usr/X11R6/lib/X11/</file> is permitted but discouraged;
7306 package maintainers should determine if subdirectories of
7307 <file>/usr/lib/</file> and <file>/usr/share/</file> can be used
7308 instead. (The use of symbolic links from the
7309 <file>X11R6</file> directories to other FHS-compliant
7310 locations is encouraged if the program is not easily
7311 configured to look elsewhere for its files.)
7315 Packages must not provide or install files into the directories
7316 <file>/usr/bin/X11/</file>, <file>/usr/include/X11/</file> or
7317 <file>/usr/lib/X11/</file>. Files within a package should,
7318 however, make reference to these directories, rather than
7319 their <tt>X11R6</tt>-named counterparts
7320 <file>/usr/X11R6/bin/</file>, <file>/usr/X11R6/include/X11/</file>
7321 and <file>/usr/X11R6/lib/X11/</file>, if the resources being
7322 referred to have not been moved to other FHS-compliant
7328 <heading>The OSF/Motif and OpenMotif libraries</heading>
7331 <em>Programs that require the non-DFSG-compliant OSF/Motif or
7332 OpenMotif libraries</em><footnote>
7333 OSF/Motif and OpenMotif are collectively referred to as
7334 "Motif" in this policy document.
7336 should be compiled against and tested with LessTif (a free
7337 re-implementation of Motif) instead. If the maintainer
7338 judges that the program or programs do not work
7339 sufficiently well with LessTif to be distributed and
7340 supported, but do so when compiled against Motif, then two
7341 versions of the package should be created; one linked
7342 statically against Motif and with <tt>-smotif</tt>
7343 appended to the package name, and one linked dynamically
7344 against Motif and with <tt>-dmotif</tt> appended to the
7349 Both Motif-linked versions are dependent
7350 upon non-DFSG-compliant software and thus cannot be
7351 uploaded to the <em>main</em> distribution; if the
7352 software is itself DFSG-compliant it may be uploaded to
7353 the <em>contrib</em> distribution. While known existing
7354 versions of Motif permit unlimited redistribution of
7355 binaries linked against the library (whether statically or
7356 dynamically), it is the package maintainer's
7357 responsibility to determine whether this is permitted by
7358 the license of the copy of Motif in his or her possession.
7364 <heading>Perl programs and modules</heading>
7367 Perl programs and modules should follow the current Perl policy.
7371 The Perl policy can be found in the <tt>perl-policy</tt>
7372 files in the <tt>debian-policy</tt> package.
7373 They are also available from the Debian web mirrors at
7374 <tt><url name="/doc/packaging-manuals/perl-policy/"
7375 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>
7376 and from the Debian archive mirrors at
7377 <tt><url name="/doc/package-developer/perl-policy.txt.gz"
7378 id="http://ftp.debian.org/debian/doc/package-developer/perl-policy.txt.gz"></tt>.
7383 <heading>Emacs lisp programs</heading>
7386 Please refer to the "Debian Emacs Policy" for details of how to
7387 package emacs lisp programs.
7391 The Emacs policy is available in
7392 <file>debian-emacs-policy.gz</file> of the
7393 <package>emacsen-common</package> package.
7394 It is also available from the Debian web mirrors at
7395 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
7396 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
7401 <heading>Games</heading>
7404 The permissions on <file>/var/games</file> are mode 755, owner
7405 <tt>root</tt> and group <tt>root</tt>.
7409 Each game decides on its own security policy.</p>
7412 Games which require protected, privileged access to
7413 high-score files, savegames, etc., may be made
7414 set-<em>group</em>-id (mode 2755) and owned by
7415 <tt>root.games</tt>, and use files and directories with
7416 appropriate permissions (770 <tt>root.games</tt>, for
7417 example). They must not be made
7418 set-<em>user</em>-id, as this causes security problems. (If
7419 an attacker can subvert any set-user-id game they can
7420 overwrite the executable of any other, causing other players
7421 of these games to run a Trojan horse program. With a
7422 set-group-id game the attacker only gets access to less
7423 important game data, and if they can get at the other
7424 players' accounts at all it will take considerably more
7428 Some packages, for example some fortune cookie programs, are
7429 configured by the upstream authors to install with their
7430 data files or other static information made unreadable so
7431 that they can only be accessed through set-id programs
7432 provided. You should not do this in a Debian package: anyone can
7433 download the <file>.deb</file> file and read the data from it,
7434 so there is no point making the files unreadable. Not
7435 making the files unreadable also means that you don't have
7436 to make so many programs set-id, which reduces the risk of a
7440 As described in the FHS, binaries of games should be
7441 installed in the directory <file>/usr/games</file>. This also
7442 applies to games that use the X Window System. Manual pages
7443 for games (X and non-X games) should be installed in
7444 <file>/usr/share/man/man6</file>.</p>
7448 <chapt id="docs"><heading>Documentation</heading>
7452 <heading>Manual pages</heading>
7455 You should install manual pages in <prgn>nroff</prgn> source
7456 form, in appropriate places under <file>/usr/share/man</file>.
7457 You should only use sections 1 to 9 (see the FHS for more
7458 details). You must not install a preformatted "cat page".
7462 Each program, utility, and function should have an
7463 associated manual page included in the same package. It is
7464 suggested that all configuration files also have a manual
7465 page included as well. Manual pages for protocols and other
7466 auxiliary things are optional.
7470 If no manual page is available, this is considered as a bug
7471 and should be reported to the Debian Bug Tracking System (the
7472 maintainer of the package is allowed to write this bug report
7473 themselves, if they so desire). Do not close the bug report
7474 until a proper manpage is available.<footnote>
7475 It is not very hard to write a man page. See the
7476 <url id="http://www.schweikhardt.net/man_page_howto.html"
7477 name="Man-Page-HOWTO">,
7478 <manref name="man" section="7">, the examples
7479 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
7480 the helper programs <prgn>help2man</prgn>, or the
7481 directory <file>/usr/share/doc/man-db/examples</file>.
7486 You may forward a complaint about a missing manpage to the
7487 upstream authors, and mark the bug as forwarded in the
7488 Debian bug tracking system. Even though the GNU Project do
7489 not in general consider the lack of a manpage to be a bug,
7490 we do; if they tell you that they don't consider it a bug
7491 you should leave the bug in our bug tracking system open
7496 Manual pages should be installed compressed using <tt>gzip -9</tt>.
7500 If one manpage needs to be accessible via several names it
7501 is better to use a symbolic link than the <file>.so</file>
7502 feature, but there is no need to fiddle with the relevant
7503 parts of the upstream source to change from <file>.so</file> to
7504 symlinks: don't do it unless it's easy. You should not
7505 create hard links in the manual page directories, nor put
7506 absolute filenames in <file>.so</file> directives. The filename
7507 in a <file>.so</file> in a manpage should be relative to the
7508 base of the manpage tree (usually
7509 <file>/usr/share/man</file>). If you do not create any links
7510 (whether symlinks, hard links, or <tt>.so</tt> directives)
7511 in the filesystem to the alternate names of the manpage,
7512 then you should not rely on <prgn>man</prgn> finding your
7513 manpage under those names based solely on the information in
7514 the manpage's header.<footnote>
7515 Supporting this in <prgn>man</prgn> often requires
7516 unreasonable processing time to find a manual page or to
7517 report that none exists, and moves knowledge into man's
7518 database that would be better left in the filesystem.
7519 This support is therefore deprecated and will cease to
7520 be present in the future.
7526 <heading>Info documents</heading>
7529 Info documents should be installed in <file>/usr/share/info</file>.
7530 They should be compressed with <tt>gzip -9</tt>.
7534 Your package should call <prgn>install-info</prgn> to update
7535 the Info <file>dir</file> file in its <prgn>postinst</prgn>
7536 script when called with a <tt>configure</tt> argument, for
7538 <example compact="compact">
7539 install-info --quiet --section Development Development \
7540 /usr/share/info/foobar.info
7544 It is a good idea to specify a section for the location of
7545 your program; this is done with the <tt>--section</tt>
7546 switch. To determine which section to use, you should look
7547 at <file>/usr/share/info/dir</file> on your system and choose the most
7548 relevant (or create a new section if none of the current
7549 sections are relevant). Note that the <tt>--section</tt>
7550 flag takes two arguments; the first is a regular expression
7551 to match (case-insensitively) against an existing section,
7552 the second is used when creating a new one.</p>
7555 You should remove the entries in the <prgn>prerm</prgn>
7556 script when called with a <tt>remove</tt> argument:
7557 <example compact="compact">
7558 install-info --quiet --remove /usr/share/info/foobar.info
7562 If <prgn>install-info</prgn> cannot find a description entry
7563 in the Info file you must supply one. See <manref
7564 name="install-info" section="8"> for details.</p>
7568 <heading>Additional documentation</heading>
7571 Any additional documentation that comes with the package may
7572 be installed at the discretion of the package maintainer.
7573 Text documentation should be installed in the directory
7574 <file>/usr/share/doc/<var>package</var></file>, where
7575 <var>package</var> is the name of the package, and
7576 compressed with <tt>gzip -9</tt> unless it is small.
7580 If a package comes with large amounts of documentation which
7581 many users of the package will not require you should create
7582 a separate binary package to contain it, so that it does not
7583 take up disk space on the machines of users who do not need
7584 or want it installed.</p>
7587 It is often a good idea to put text information files
7588 (<file>README</file>s, changelogs, and so forth) that come with
7589 the source package in <file>/usr/share/doc/<var>package</var></file>
7590 in the binary package. However, you don't need to install
7591 the instructions for building and installing the package, of
7595 Packages must not require the existence of any files in
7596 <file>/usr/share/doc/</file> in order to function
7598 The system administrator should be able to
7599 delete files in <file>/usr/share/doc/</file> without causing
7600 any programs to break.
7602 Any files that are referenced by programs but are also
7603 useful as standalone documentation should be installed under
7604 <file>/usr/share/<var>package</var>/</file> with symbolic links from
7605 <file>/usr/share/doc/<var>package</var></file>.
7609 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
7610 link to another directory in <file>/usr/share/doc</file> only if
7611 the two packages both come from the same source and the
7612 first package Depends on the second.
7616 Former Debian releases placed all additional documentation
7617 in <file>/usr/doc/<var>package</var></file>. This has been
7618 changed to <file>/usr/share/doc/<var>package</var></file>,
7619 and packages must not put documentation in the directory
7620 <file>/usr/doc/<var>package</var></file>. <footnote>
7621 At this phase of the transition, we no longer require a
7622 symbolic link in <file>/usr/doc/</file>. At a later point,
7623 policy shall change to make the symbolic links a bug.
7629 <heading>Preferred documentation formats</heading>
7632 The unification of Debian documentation is being carried out
7636 If your package comes with extensive documentation in a
7637 markup format that can be converted to various other formats
7638 you should if possible ship HTML versions in a binary
7639 package, in the directory
7640 <file>/usr/share/doc/<var>appropriate-package</var></file> or
7641 its subdirectories.<footnote>
7642 The rationale: The important thing here is that HTML
7643 docs should be available in <em>some</em> package, not
7644 necessarily in the main binary package.
7649 Other formats such as PostScript may be provided at the
7650 package maintainer's discretion.
7654 <sect id="copyrightfile">
7655 <heading>Copyright information</heading>
7658 Every package must be accompanied by a verbatim copy of its
7659 copyright and distribution license in the file
7660 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
7661 file must neither be compressed nor be a symbolic link.
7665 In addition, the copyright file must say where the upstream
7666 sources (if any) were obtained. It should name the original
7667 authors of the package and the Debian maintainer(s) who were
7668 involved with its creation.</p>
7671 A copy of the file which will be installed in
7672 <file>/usr/share/doc/<var>package</var>/copyright</file> should
7673 be in <file>debian/copyright</file> in the source package.
7677 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
7678 link to another directory in <file>/usr/share/doc</file> only if
7679 the two packages both come from the same source and the
7680 first package Depends on the second. These rules are
7681 important because copyrights must be extractable by
7686 Packages distributed under the UCB BSD license, the Artistic
7687 license, the GNU GPL, and the GNU LGPL should refer to the
7688 files <file>/usr/share/common-licenses/BSD</file>,
7689 <file>/usr/share/common-licenses/Artistic</file>,
7690 <file>/usr/share/common-licenses/GPL</file>, and
7691 <file>/usr/share/common-licenses/LGPL</file> respectively,
7692 rather than quoting them in the copyright file.
7696 You should not use the copyright file as a general <file>README</file>
7697 file. If your package has such a file it should be
7698 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
7699 <file>README.Debian</file> or some other appropriate place.</p>
7703 <heading>Examples</heading>
7706 Any examples (configurations, source files, whatever),
7707 should be installed in a directory
7708 <file>/usr/share/doc/<var>package</var>/examples</file>. These
7709 files should not be referenced by any program: they're there
7710 for the benefit of the system administrator and users as
7711 documentation only. Architecture-specific example files
7712 should be installed in a directory
7713 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
7715 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
7716 latter directory itself may be a symbolic link to the
7721 If the purpose of a package is to provide examples, then the
7722 example files may be installed into
7723 <file>/usr/share/doc/<var>package</var></file>.
7727 <sect id="changelogs">
7728 <heading>Changelog files</heading>
7731 The Debian changelog file (<file>debian/changelog</file>) should
7732 explain briefly what modifications were made in the Debian version
7733 of the package compared to the upstream one. Other changes and
7734 updates to the package should also be documented in this file.
7738 Mistakes in changelogs are usually best rectified by
7739 making a new changelog entry rather than "rewriting history"
7740 by editing old changelog entries.
7744 The format of the <file>debian/changelog</file> file is described
7745 in <ref id="dpkgchangelog">. In non-experimental packages you must
7746 use a format for <file>debian/changelog</file> which is supported
7747 by the most recent released version of <prgn>dpkg</prgn>.<footnote>
7748 If you wish to use an alternative format, you may do so as
7749 long as you include a parser for it in your source package.
7750 The parser must have an API compatible with that expected by
7751 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-gencontrol</prgn>.
7752 If there is general interest in the new format, you should
7753 contact the <package>dpkg</package> maintainer to have the
7754 parser script for it included in the <prgn>dpkg</prgn>
7755 package. (You will need to agree that the parser and its
7756 manpage may be distributed under the GNU GPL, just as the rest
7757 of <prgn>dpkg</prgn> is.)
7762 Packages that are not Debian-native must contain a
7763 compressed copy of the <file>debian/changelog</file> file from
7764 the Debian source tree in
7765 <file>/usr/share/doc/<var>package</var></file> with the name
7766 <file>changelog.Debian.gz</file>.
7770 If an upstream changelog is available, it should be accessible as
7771 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
7772 plain text. If the upstream changelog is distributed in
7773 HTML, it should be made available in that form as
7774 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
7775 and a plain text <file>changelog.gz</file> should be generated
7776 from it using, for example, <tt>lynx -dump -nolist</tt>. If
7777 the upstream changelog files do not already conform to this
7778 naming convention, then this may be achieved either by
7779 renaming the files, or by adding a symbolic link, at the
7780 maintainer's discretion.<footnote>
7781 Rationale: People should not have to look in places for
7782 upstream changelogs merely because they are given
7783 different names or are distributed in HTML format.
7788 All of these files should be installed compressed using
7789 <tt>gzip -9</tt>, as they will become large with time even
7790 if they start out small.
7794 If the package has only one changelog which is used both as
7795 the Debian changelog and the upstream one because there is
7796 no separate upstream maintainer then that changelog should
7797 usually be installed as
7798 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
7799 there is a separate upstream maintainer, but no upstream
7800 changelog, then the Debian changelog should still be called
7801 <file>changelog.Debian.gz</file>.</p>
7806 <appendix id="pkg-scope">
7807 <heading>Introduction and scope of these appendices</heading>
7810 These appendices are taken essentially verbatim from the
7811 now-deprecated Packaging Manual, version 3.2.1.0. They are
7812 the chapters which are likely to be of use to package
7813 maintainers and which have not already been included in the
7814 policy document itself. Most of these sections are very likely
7815 not relevant to policy; they should be treated as
7816 documentation for the packaging system. Please note that these
7817 appendices are included for convenience, and for historical
7818 reasons: they used to be part of policy package, and they have
7819 not yet been incorporated into dpkg documentation. However,
7820 they still have value, and hence they are presented here.
7823 They have not yet been checked to ensure that they are
7824 compatible with the contents of policy, and if there are any
7825 contradictions, the version in the main policy document takes
7826 precedence. The remaining chapters of the old Packaging
7827 Manual have also not been read in detail to ensure that there
7828 are not parts which have been left out. Both of these will be
7833 <prgn>dpkg</prgn> is a suite of programs for creating binary
7834 package files and installing and removing them on Unix
7836 <prgn>dpkg</prgn> is targetted primarily at Debian
7837 GNU/Linux, but may work on or be ported to other
7843 The binary packages are designed for the management of
7844 installed executable programs (usually compiled binaries) and
7845 their associated data, though source code examples and
7846 documentation are provided as part of some packages.</p>
7849 This manual describes the technical aspects of creating Debian
7850 binary packages (<file>.deb</file> files). It documents the
7851 behaviour of the package management programs
7852 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
7853 they interact with packages.</p>
7856 It also documents the interaction between
7857 <prgn>dselect</prgn>'s core and the access method scripts it
7858 uses to actually install the selected packages, and describes
7859 how to create a new access method.</p>
7862 This manual does not go into detail about the options and
7863 usage of the package building and installation tools. It
7864 should therefore be read in conjuction with those programs'
7869 The utility programs which are provided with <prgn>dpkg</prgn>
7870 for managing various system configuration and similar issues,
7871 such as <prgn>update-rc.d</prgn> and
7872 <prgn>install-info</prgn>, are not described in detail here -
7873 please see their manpages.
7877 It is assumed that the reader is reasonably familiar with the
7878 <prgn>dpkg</prgn> System Administrators' manual.
7879 Unfortunately this manual does not yet exist.
7883 The Debian version of the FSF's GNU hello program is provided
7884 as an example for people wishing to create Debian
7885 packages. The Debian <prgn>debmake</prgn> package is
7886 recommended as a very helpful tool in creating and maintaining
7887 Debian packages. However, while the tools and examples are
7888 helpful, they do not replace the need to read and follow the
7889 Policy and Programmer's Manual.</p>
7892 <appendix id="pkg-binarypkg"><heading>Binary packages (from old
7897 The binary package has two main sections. The first part
7898 consists of various control information files and scripts used
7899 by <prgn>dpkg</prgn> when installing and removing. See <ref
7900 id="pkg-controlarea">.
7904 The second part is an archive containing the files and
7905 directories to be installed.
7909 In the future binary packages may also contain other
7910 components, such as checksums and digital signatures. The
7911 format for the archive is described in full in the
7912 <file>deb(5)</file> manpage.
7916 <sect id="pkg-bincreating"><heading>Creating package files -
7917 <prgn>dpkg-deb</prgn>
7921 All manipulation of binary package files is done by
7922 <prgn>dpkg-deb</prgn>; it's the only program that has
7923 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
7924 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
7925 will spot that the options requested are appropriate to
7926 <prgn>dpkg-deb</prgn> and invoke that instead with the same
7931 In order to create a binary package you must make a
7932 directory tree which contains all the files and directories
7933 you want to have in the filesystem data part of the package.
7934 In Debian-format source packages this directory is usually
7935 <file>debian/tmp</file>, relative to the top of the package's
7940 They should have the locations (relative to the root of the
7941 directory tree you're constructing) ownerships and
7942 permissions which you want them to have on the system when
7947 With current versions of <prgn>dpkg</prgn> the uid/username
7948 and gid/groupname mappings for the users and groups being
7949 used should be the same on the system where the package is
7950 built and the one where it is installed.
7954 You need to add one special directory to the root of the
7955 miniature filesystem tree you're creating:
7956 <prgn>DEBIAN</prgn>. It should contain the control
7957 information files, notably the binary package control file
7958 (see <ref id="pkg-controlfile">).
7962 The <prgn>DEBIAN</prgn> directory will not appear in the
7963 filesystem archive of the package, and so won't be installed
7964 by <prgn>dpkg</prgn> when the package is installed.
7968 When you've prepared the package, you should invoke:
7970 dpkg --build <var>directory</var>
7975 This will build the package in
7976 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
7977 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
7978 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
7983 See the manpage <manref name="dpkg-deb" section="8"> for details of how
7984 to examine the contents of this newly-created file. You may find the
7985 output of following commands enlightening:
7987 dpkg-deb --info <var>filename</var>.deb
7988 dpkg-deb --contents <var>filename</var>.deb
7989 dpkg --contents <var>filename</var>.deb
7991 To view the copyright file for a package you could use this command:
7993 dpkg --fsys-tarfile <var>filename</var>.deb | tar xof usr/share/doc/<var>\*</var>copyright | less
7998 <sect id="pkg-controlarea">
8000 Package control information files
8004 The control information portion of a binary package is a
8005 collection of files with names known to <prgn>dpkg</prgn>.
8006 It will treat the contents of these files specially - some
8007 of them contain information used by <prgn>dpkg</prgn> when
8008 installing or removing the package; others are scripts which
8009 the package maintainer wants <prgn>dpkg</prgn> to run.
8013 It is possible to put other files in the package control
8014 area, but this is not generally a good idea (though they
8015 will largely be ignored).
8019 Here is a brief list of the control info files supported by
8020 <prgn>dpkg</prgn> and a summary of what they're used for.
8025 <tag><tt>control</tt>
8029 This is the key description file used by
8030 <prgn>dpkg</prgn>. It specifies the package's name
8031 and version, gives its description for the user,
8032 states its relationships with other packages, and so
8033 forth. See <ref id="pkg-controlfile">.
8037 It is usually generated automatically from information
8038 in the source package by the
8039 <prgn>dpkg-gencontrol</prgn> program, and with
8040 assistance from <prgn>dpkg-shlibdeps</prgn>. See <ref
8041 id="pkg-sourcetools">.</p>
8044 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
8050 These are exectuable files (usually scripts) which
8051 <prgn>dpkg</prgn> runs during installation, upgrade
8052 and removal of packages. They allow the package to
8053 deal with matters which are particular to that package
8054 or require more complicated processing than that
8055 provided by <prgn>dpkg</prgn>. Details of when and
8056 how they are called are in <ref
8057 id="maintainerscripts">.
8061 It is very important to make these scripts
8064 That means that if it runs successfully or fails
8065 and then you call it again it doesn't bomb out,
8066 but just ensures that everything is the way it
8068 </footnote> This is so that if an error occurs, the
8069 user interrupts <prgn>dpkg</prgn> or some other
8070 unforeseen circumstance happens you don't leave the
8071 user with a badly-broken package.
8075 The maintainer scripts are guaranteed to run with a
8076 controlling terminal and can interact with the user.
8077 If they need to prompt for passwords, do full-screen
8078 interaction or something similar you should do these
8079 things to and from <file>/dev/tty</file>, since
8080 <prgn>dpkg</prgn> will at some point redirect scripts'
8081 standard input and output so that it can log the
8082 installation process. Likewise, because these scripts
8083 may be executed with standard output redirected into a
8084 pipe for logging purposes, Perl scripts should set
8085 unbuffered output by setting <tt>$|=1</tt> so that the
8086 output is printed immediately rather than being
8091 Each script should return a zero exit status for
8092 success, or a nonzero one for failure.</p>
8095 <tag><tt>conffiles</tt>
8100 This file contains a list of configuration files which
8101 are to be handled automatically by <prgn>dpkg</prgn>
8102 (see <ref id="pkg-conffiles">). Note that not necessarily
8103 every configuration file should be listed here.</p>
8106 <tag><tt>shlibs</tt>
8111 This file contains a list of the shared libraries
8112 supplied by the package, with dependency details for
8113 each. This is used by <prgn>dpkg-shlibdeps</prgn>
8114 when it determines what dependencies are required in a
8115 package control file. The <tt>shlibs</tt> file format
8116 is described on <ref id="shlibs">.
8122 <sect id="pkg-controlfile">
8124 The main control information file: <tt>control</tt>
8127 The most important control information file used by
8128 <prgn>dpkg</prgn> when it installs a package is
8129 <tt>control</tt>. It contains all the package"s "vital
8134 The binary package control files of packages built from
8135 Debian sources are made by a special tool,
8136 <prgn>dpkg-gencontrol</prgn>, which reads
8137 <file>debian/control</file> and <file>debian/changelog</file> to
8138 find the information it needs. See <ref id="pkg-sourcepkg"> for
8143 The fields in binary package control files are:
8144 <list compact="compact">
8146 <p><qref id="pkg-f-Package"><tt>Package</tt></qref> (mandatory)</p>
8149 <p><qref id="versions"><tt>Version</tt></qref> (mandatory)</p>
8151 <item><p><qref id="pkg-f-Architecture"><tt>Architecture</tt></qref>
8154 This field should appear in all packages, though
8155 <prgn>dpkg</prgn> doesn't require it yet so that
8156 old packages can still be installed.
8161 <p><qref id="relationships"><tt>Depends</tt>,
8162 <tt>Provides</tt> et al.</qref></p>
8165 <p><qref id="pkg-f-Essential"><tt>Essential</tt></qref></p>
8168 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
8171 <p><qref id="pkg-f-classification"><tt>Section</tt>,
8172 <tt>Priority</tt></qref></p>
8175 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
8178 <p><qref id="descriptions"><tt>Description</tt></qref></p>
8182 <qref id="pkg-f-Installed-Size"><tt>Installed-Size</tt></qref>
8188 A description of the syntax of control files and the purpose
8189 of these fields is available in <ref id="pkg-controlfields">.
8194 <heading>Time Stamps</heading>
8196 Maintainers are encouraged to preserve the modification
8197 times of the upstream source files in a package, as far as
8198 is reasonably possible.
8200 The rationale is that there is some information conveyed
8201 by knowing the age of the file, for example, you could
8202 recognize that some documentation is very old by looking
8203 at the modification time, so it would be nice if the
8204 modification time of the upstream source would be
8211 <appendix id="pkg-sourcepkg">
8212 <heading>Source packages (from old Packaging Manual) </heading>
8215 The Debian binary packages in the distribution are generated
8216 from Debian sources, which are in a special format to assist
8217 the easy and automatic building of binaries.
8220 <sect id="pkg-sourcetools">
8221 <heading>Tools for processing source packages</heading>
8224 Various tools are provided for manipulating source packages;
8225 they pack and unpack sources and help build of binary
8226 packages and help manage the distribution of new versions.
8230 They are introduced and typical uses described here; see
8231 <manref name="dpkg-source" section="1"> for full
8232 documentation about their arguments and operation.
8236 For examples of how to construct a Debian source package,
8237 and how to use those utilities that are used by Debian
8238 source packages, please see the <prgn>hello</prgn> example
8244 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
8249 This program is frequently used by hand, and is also
8250 called from package-independent automated building scripts
8251 such as <prgn>dpkg-buildpackage</prgn>.
8255 To unpack a package it is typically invoked with
8257 dpkg-source -x <var>.../path/to/filename</var>.dsc
8262 with the <file><var>filename</var>.tar.gz</file> and
8263 <file><var>filename</var>.diff.gz</file> (if applicable) in
8264 the same directory. It unpacks into
8265 <file><var>package</var>-<var>version</var></file>, and if
8267 <file><var>package</var>-<var>version</var>.orig</file>, in
8268 the current directory.
8272 To create a packed source archive it is typically invoked:
8274 dpkg-source -b <var>package</var>-<var>version</var>
8279 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
8280 <file>.diff.gz</file> (if appropriate) in the current
8281 directory. <prgn>dpkg-source</prgn> does not clean the
8282 source tree first - this must be done separately if it is
8287 See also <ref id="pkg-sourcearchives">.</p>
8293 <prgn>dpkg-buildpackage</prgn> - overall package-building
8298 <prgn>dpkg-buildpackage</prgn> is a script which invokes
8299 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
8300 targets <tt>clean</tt>, <tt>build</tt> and
8301 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
8302 <prgn>pgp</prgn> to build a signed source and binary
8307 It is usually invoked by hand from the top level of the
8308 built or unbuilt source directory. It may be invoked with
8309 no arguments; useful arguments include:
8310 <taglist compact="compact">
8311 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
8314 Do not PGP-sign the <tt>.changes</tt> file or the
8315 source package <tt>.dsc</tt> file, respectively.</p>
8317 <tag><tt>-p<var>pgp-command</var></tt></tag>
8320 Invoke <var>pgp-command</var> instead of finding
8321 <tt>pgp</tt> on the <prgn>PATH</prgn>.
8322 <var>pgp-command</var> must behave just like
8323 <prgn>pgp</prgn>.</p>
8325 <tag><tt>-r<var>root-command</var></tt></tag>
8328 When root privilege is required, invoke the command
8329 <var>root-command</var>. <var>root-command</var>
8330 should invoke its first argument as a command, from
8331 the <prgn>PATH</prgn> if necessary, and pass its
8332 second and subsequent arguments to the command it
8333 calls. If no <var>root-command</var> is supplied
8334 then <var>dpkg-buildpackage</var> will take no
8335 special action to gain root privilege, so that for
8336 most packages it will have to be invoked as root to
8339 <tag><tt>-b</tt>, <tt>-B</tt></tag>
8342 Two types of binary-only build and upload - see
8343 <manref name="dpkg-source" section="1">.
8352 <prgn>dpkg-gencontrol</prgn> - generates binary package
8357 This program is usually called from <file>debian/rules</file>
8358 (see <ref id="pkg-sourcetree">) in the top level of the source
8363 This is usually done just before the files and directories in the
8364 temporary directory tree where the package is being built have their
8365 permissions and ownerships set and the package is constructed using
8366 <prgn>dpkg-deb/</prgn>
8368 This is so that the control file which is produced has
8369 the right permissions
8374 <prgn>dpkg-gencontrol</prgn> must be called after all the
8375 files which are to go into the package have been placed in
8376 the temporary build directory, so that its calculation of
8377 the installed size of a package is correct.
8381 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
8382 be run after <prgn>dpkg-shlibdeps</prgn> so that the
8383 variable substitutions created by
8384 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
8389 For a package which generates only one binary package, and
8390 which builds it in <file>debian/tmp</file> relative to the top
8391 of the source package, it is usually sufficient to call
8392 <prgn>dpkg-gencontrol</prgn>.
8396 Sources which build several binaries will typically need
8399 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
8400 </example> The <tt>-P</tt> tells
8401 <prgn>dpkg-gencontrol</prgn> that the package is being
8402 built in a non-default directory, and the <tt>-p</tt>
8403 tells it which package's control file should be generated.
8407 <prgn>dpkg-gencontrol</prgn> also adds information to the
8408 list of files in <file>debian/files</file>, for the benefit of
8409 (for example) a future invocation of
8410 <prgn>dpkg-genchanges</prgn>.</p>
8415 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
8420 This program is usually called from <file>debian/rules</file>
8421 just before <prgn>dpkg-gencontrol</prgn> (see <ref
8422 id="pkg-sourcetree">), in the top level of the source tree.
8426 Its arguments are executables.
8429 In a forthcoming dpkg version,
8430 <prgn>dpkg-shlibdeps</prgn> would be required to be
8431 called on shared libraries as well.
8434 They may be specified either in the locations in the
8435 source tree where they are created or in the locations
8436 in the temporary build tree where they are installed
8437 prior to binary package creation.
8439 </footnote> for which shared library dependencies should
8440 be included in the binary package's control file.
8444 If some of the found shared libraries should only
8445 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
8446 some warrant a <tt>Pre-Depends</tt>, this can be achieved
8447 by using the <tt>-d<var>dependency-field</var></tt> option
8448 before those executable(s). (Each <tt>-d</tt> option
8449 takes effect until the next <tt>-d</tt>.)
8453 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
8454 output control file to be modified. Instead by default it
8455 adds to the <file>debian/substvars</file> file variable
8456 settings like <tt>shlibs:Depends</tt>. These variable
8457 settings must be referenced in dependency fields in the
8458 appropriate per-binary-package sections of the source
8463 For example, the <prgn>procps</prgn> package generates two
8464 kinds of binaries, simple C binaries like <prgn>ps</prgn>
8465 which require a predependency and full-screen ncurses
8466 binaries like <prgn>top</prgn> which require only a
8467 recommendation. It can say in its <file>debian/rules</file>:
8469 dpkg-shlibdeps -dPre-Depends ps -dRecommends top
8471 and then in its main control file <file>debian/control</file>:
8475 Pre-Depends: ${shlibs:Pre-Depends}
8476 Recommends: ${shlibs:Recommends}
8482 Sources which produce several binary packages with
8483 different shared library dependency requirements can use
8484 the <tt>-p<var>varnameprefix</var></tt> option to override
8485 the default <tt>shlibs:</tt> prefix (one invocation of
8486 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
8487 They can thus produce several sets of dependency
8488 variables, each of the form
8489 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
8490 which can be referred to in the appropriate parts of the
8491 binary package control files.
8498 <prgn>dpkg-distaddfile</prgn> - adds a file to
8499 <file>debian/files</file>
8503 Some packages' uploads need to include files other than
8504 the source and binary package files.
8508 <prgn>dpkg-distaddfile</prgn> adds a file to the
8509 <file>debian/files</file> file so that it will be included in
8510 the <file>.changes</file> file when
8511 <prgn>dpkg-genchanges</prgn> is run.
8515 It is usually invoked from the <tt>binary</tt> target of
8516 <file>debian/rules</file>:
8518 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
8520 The <var>filename</var> is relative to the directory where
8521 <prgn>dpkg-genchanges</prgn> will expect to find it - this
8522 is usually the directory above the top level of the source
8523 tree. The <file>debian/rules</file> target should put the
8524 file there just before or just after calling
8525 <prgn>dpkg-distaddfile</prgn>.
8529 The <var>section</var> and <var>priority</var> are passed
8530 unchanged into the resulting <file>.changes</file> file. See
8531 <ref id="pkg-f-classification">.
8536 <sect1><heading><prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file> upload
8541 This program is usually called by package-independent
8542 automatic building scripts such as
8543 <prgn>dpkg-buildpackage</prgn>, but it may also be called
8548 It is usually called in the top level of a built source
8549 tree, and when invoked with no arguments will print out a
8550 straightforward <file>.changes</file> file based on the
8551 information in the source package's changelog and control
8552 file and the binary and source packages which should have
8558 <sect1><heading><prgn>dpkg-parsechangelog</prgn> - produces parsed representation of
8563 This program is used internally by
8564 <prgn>dpkg-source</prgn> et al. It may also occasionally
8565 be useful in <file>debian/rules</file> and elsewhere. It
8566 parses a changelog, <file>debian/changelog</file> by default,
8567 and prints a control-file format representation of the
8568 information in it to standard output.
8572 <sect1 id="pkg-dpkgarch"><heading><prgn>dpkg-architecture</prgn> -
8573 information about the build and host system
8577 This program can be used manually, but is also invoked by
8578 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
8579 to set environment or make variables which specify the build and
8580 host architecture for the package building process.
8585 <sect id="pkg-sourcetree"><heading>The Debianised source tree
8589 The source archive scheme described later is intended to
8590 allow a Debianised source tree with some associated control
8591 information to be reproduced and transported easily. The
8592 Debianised source tree is a version of the original program
8593 with certain files added for the benefit of the
8594 Debianisation process, and with any other changes required
8595 made to the rest of the source code and installation
8600 The extra files created for Debian are in the subdirectory
8601 <file>debian</file> of the top level of the Debianised source
8602 tree. They are described below.
8605 <sect1 id="pkg-debianrules"><heading><file>debian/rules</file> - the main building
8610 This file is an executable makefile, and contains the
8611 package-specific recipies for compiling the package and
8612 building binary package(s) out of the source.
8616 It must start with the line <tt>#!/usr/bin/make -f</tt>,
8617 so that it can be invoked by saying its name rather than
8618 invoking <prgn>make</prgn> explicitly.
8622 Since an interactive <file>debian/rules</file> script makes it
8623 impossible to autocompile that package and also makes it
8624 hard for other people to reproduce the same binary
8625 package, all <strong>required targets</strong> have to be
8626 non-interactive. At a minimul, required targets are the
8627 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
8628 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>, and
8629 <em>build</em>. It also follows that any target that these
8630 targets depend on must also be non-interactive.
8634 The targets which are required to be present are:
8636 <tag><tt>build</tt></tag>
8639 This should perform all non-interactive
8640 configuration and compilation of the package. If a
8641 package has an interactive pre-build configuration
8642 routine, the Debianised source package should be
8643 built after this has taken place, so that it can be
8644 built without rerunning the configuration.
8648 A package may also provide both of the targets
8649 <tt>build-arch</tt> and <tt>build-indep</tt>. The
8650 <tt>build-arch</tt> target, if provided, should
8651 perform all non-interactive configuration and
8652 compilation required for producing all
8653 architecture-dependant binary packages (those packages
8654 for which the body of the <tt>Architecture</tt> field
8655 in <tt>debian/control</tt> is not <tt>all</tt>).
8656 Similarly, the <tt>build-indep</tt> target, if
8657 provided, should perform all non-interactive
8658 configuration and compilation required for producing
8659 all architecture-independent binary packages (those
8660 packages for which the body of the
8661 <tt>Architecture</tt> field in <tt>debian/control</tt>
8662 is <tt>all</tt>). The <tt>build</tt> target should
8663 depend on those of the targets <tt>build-arch</tt> and
8664 <tt>build-indep</tt> that are provided in the rules
8669 If one or both of the targets <tt>build-arch</tt> and
8670 <tt>build-indep</tt> are not provided, then invoking
8671 <file>debian/rules</file> with one of the not-provided
8672 targets as arguments should produce a exit status code
8673 of 2. Usually this is provided automatically by make
8674 if the target is missing.
8678 For some packages, notably ones where the same
8679 source tree is compiled in different ways to produce
8680 two binary packages, the <tt>build</tt> target does
8681 not make much sense. For these packages it is good
8682 enough to provide two (or more) targets
8683 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
8684 for each of the ways of building the package, and a
8685 <tt>build</tt> target that does nothing. The
8686 <tt>binary</tt> target will have to build the
8687 package in each of the possible ways and make the
8688 binary package out of each.
8692 The targets <tt>build</tt>, <tt>build-arch</tt>
8693 and <tt>build-indep</tt> target must not do
8694 anything that might require root privilege.
8698 The <tt>build</tt> target may need to run
8699 <tt>clean</tt> first - see below.
8703 When a package has a configuration routine that takes
8704 a long time, or when the makefiles are poorly
8705 designed, or when <tt>build</tt> needs to run
8706 <tt>clean</tt> first, it is a good idea to <tt>touch
8707 build</tt> when the build process is complete. This
8708 will ensure that if <tt>debian/rules build</tt> is run
8709 again it will not rebuild the whole program.
8713 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
8714 <tt>binary-indep</tt>
8718 The <tt>binary</tt> target should be all that is
8719 necessary for the user to build the binary
8720 package. All these targets are required to be
8721 non-interactive. It is split into two parts:
8722 <tt>binary-arch</tt> builds the packages' output
8723 files which are specific to a particular
8724 architecture, and <tt>binary-indep</tt> builds
8725 those which are not.
8729 <tt>binary</tt> should usually be a target with
8730 no commands which simply depends on
8731 <prgn>binary-arch</prgn> and
8732 <prgn>binary-indep</prgn>.
8736 Both <prgn>binary-*</prgn> targets should depend on
8737 the <tt>build</tt> target, above, so that the
8738 package is built if it has not been already. It
8739 should then create the relevant binary package(s),
8740 using <prgn>dpkg-gencontrol</prgn> to make their
8741 control files and <prgn>dpkg-deb</prgn> to build
8742 them and place them in the parent of the top level
8747 If one of the <prgn>binary-*</prgn> targets has
8748 nothing to do (this will be always be the case if
8749 the source generates only a single binary package,
8750 whether architecture-dependent or not) it
8751 <em>must</em> still exist, but should always
8756 <ref id="pkg-binarypkg"> describes how to construct
8761 The <tt>binary</tt> targets must be invoked as
8766 <tag><tt>clean</tt></tag>
8770 This should undo any effects that the
8771 <tt>build</tt> and <tt>binary</tt> targets
8772 may have had, except that it should leave alone any
8773 output files created in the parent directory by a
8774 run of <tt>binary</tt>. This target is required
8775 to be non-interactive.
8779 If a <tt>build</tt> file is touched at the end
8780 of the <tt>build</tt> target, as suggested
8781 above, it must be removed as the first thing that
8782 <tt>clean</tt> does, so that running
8783 <tt>build</tt> again after an interrupted
8784 <tt>clean</tt> doesn't think that everything is
8789 The <tt>clean</tt> target must be invoked as
8790 root if <tt>binary</tt> has been invoked since
8791 the last <tt>clean</tt>, or if
8792 <tt>build</tt> has been invoked as root (since
8793 <tt>build</tt> may create directories, for
8798 <tag><tt>get-orig-source</tt> (optional)</tag>
8802 This target fetches the most recent version of the
8803 original source package from a canonical archive
8804 site (via FTP or WWW, for example), does any
8805 necessary rearrangement to turn it into the original
8806 source tarfile format described below, and leaves it
8807 in the current directory.
8811 This target may be invoked in any directory, and
8812 should take care to clean up any temporary files it
8817 This target is optional, but providing it if
8818 possible is a good idea.
8824 The <tt>build</tt>, <tt>binary</tt> and
8825 <tt>clean</tt> targets must be invoked with a current
8826 directory of the package's top-level directory.
8831 Additional targets may exist in <file>debian/rules</file>,
8832 either as published or undocumented interfaces or for the
8833 package's internal use.
8837 The architecture we build on and build for is determined by make
8838 variables via dpkg-architecture (see <ref id="pkg-dpkgarch">). You can
8839 get the Debian architecture and the GNU style architecture
8840 specification string for the build machine as well as the host
8841 machine. Here is a list of supported make variables:
8842 <list compact="compact">
8844 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
8847 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
8848 specification string)</p>
8851 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of DEB_*_GNU_TYPE)</p>
8854 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
8860 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
8861 the build machine or <tt>HOST</tt> for specification of the machine
8866 Backward compatibility can be provided in the rules file
8867 by setting the needed variables to suitable default
8868 values, please refer to the documentation of
8869 dpkg-architecture for details.
8873 It is important to understand that the <tt>DEB_*_ARCH</tt>
8874 string does only determine which Debian architecture we
8875 build on resp. for. It should not be used to get the CPU
8876 or System information, the GNU style variables should be
8882 <sect1><heading><file>debian/control</file>
8886 This file contains version-independent details about the
8887 source package and about the binary packages it creates.
8891 It is a series of sets of control fields, each
8892 syntactically similar to a binary package control file.
8893 The sets are separated by one or more blank lines. The
8894 first set is information about the source package in
8895 general; each subsequent set describes one binary package
8896 that the source tree builds.
8900 The syntax and semantics of the fields are described below
8901 in <ref id="pkg-controlfields">.
8905 The general (binary-package-independent) fields are:
8906 <list compact="compact">
8908 <p><qref id="pkg-f-Source"><tt>Source</tt></qref> (mandatory)</p>
8911 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
8915 <qref id="pkg-f-classification"><tt>Section</tt> and
8916 <tt>Priority</tt></qref>
8917 (classification, mandatory)
8922 <qref id="relationships"><tt>Build-Depends</tt> et
8923 al.</qref> (source package interrelationships)
8928 <qref id="pkg-f-Standards-Version"><tt>Standards-Version</tt></qref>
8934 The per-binary-package fields are:
8935 <list compact="compact">
8937 <p><qref id="pkg-f-Package"><tt>Package</tt></qref> (mandatory)</p>
8941 <qref id="pkg-f-Architecture"><tt>Architecture</tt></qref>
8945 <p><qref id="descriptions"><tt>Description</tt></qref></p>
8949 <qref id="pkg-f-classification"><tt>Section</tt> and
8950 <tt>Priority</tt></qref> (classification)</p>
8953 <p><qref id="pkg-f-Essential"><tt>Essential</tt></qref></p>
8957 <qref id="relationships"><tt>Depends</tt> et
8958 al.</qref> (binary package interrelationships)
8964 These fields are used by <prgn>dpkg-gencontrol</prgn> to
8965 generate control files for binary packages (see below), by
8966 <prgn>dpkg-genchanges</prgn> to generate the
8967 <tt>.changes</tt> file to accompany the upload, and by
8968 <prgn>dpkg-source</prgn> when it creates the <file>.dsc</file>
8969 source control file as part of a source archive.
8973 The fields here may contain variable references - their
8974 values will be substituted by
8975 <prgn>dpkg-gencontrol</prgn>, <prgn>dpkg-genchanges</prgn>
8976 or <prgn>dpkg-source</prgn> when they generate output
8977 control files. See <ref id="pkg-srcsubstvars"> for details.
8980 <p> <sect2><heading>User-defined fields
8984 Additional user-defined fields may be added to the
8985 source package control file. Such fields will be
8986 ignored, and not copied to (for example) binary or
8987 source package control files or upload control files.
8991 If you wish to add additional unsupported fields to
8992 these output files you should use the mechanism
8997 Fields in the main source control information file with
8998 names starting <tt>X</tt>, followed by one or more of
8999 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
9000 be copied to the output files. Only the part of the
9001 field name after the hyphen will be used in the output
9002 file. Where the letter <tt>B</tt> is used the field
9003 will appear in binary package control files, where the
9004 letter <tt>S</tt> is used in source package control
9005 files and where <tt>C</tt> is used in upload control
9006 (<tt>.changes</tt>) files.
9010 For example, if the main source information control file
9013 XBS-Comment: I stand between the candle and the star.
9015 then the binary and source package control files will contain the
9018 Comment: I stand between the candle and the star.
9025 <sect1 id="pkg-dpkgchangelog"><heading><file>debian/changelog</file>
9029 This file records the changes to the Debian-specific parts of the
9032 Though there is nothing stopping an author who is also
9033 the Debian maintainer from using it for all their
9034 changes, it will have to be renamed if the Debian and
9035 upstream maintainers become different
9041 It has a special format which allows the package building
9042 tools to discover which version of the package is being
9043 built and find out other release-specific information.
9047 That format is a series of entries like this:
9049 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
9051 * <var>change details</var>
9052 <var>more change details</var>
9053 * <var>even more change details</var>
9055 -- <var>maintainer name and email address</var> <var>date</var>
9060 <var>package</var> and <var>version</var> are the source
9061 package name and version number.
9065 <var>distribution(s)</var> lists the distributions where
9066 this version should be installed when it is uploaded - it
9067 is copied to the <tt>Distribution</tt> field in the
9068 <tt>.changes</tt> file. See <ref id="pkg-f-Distribution">.
9072 <var>urgency</var> is the value for the <tt>Urgency</tt>
9073 field in the <file>.changes</file> file for the upload. See
9074 <ref id="pkg-f-Urgency">. It is not possible to specify an
9075 urgency containing commas; commas are used to separate
9076 <tt><var>keyword</var>=<var>value</var></tt> settings in
9077 the <prgn>dpkg</prgn> changelog format (though there is
9078 currently only one useful <var>keyword</var>,
9083 The change details may in fact be any series of lines
9084 starting with at least two spaces, but conventionally each
9085 change starts with an asterisk and a separating space and
9086 continuation lines are indented so as to bring them in
9087 line with the start of the text above. Blank lines may be
9088 used here to separate groups of changes, if desired.
9092 The maintainer name and email address should <em>not</em>
9093 necessarily be those of the usual package maintainer.
9094 They should be the details of the person doing
9095 <em>this</em> version. The information here will be
9096 copied to the <file>.changes</file> file, and then later used
9097 to send an acknowledgement when the upload has been
9102 The <var>date</var> should be in RFC822 format
9104 This is generated by the <prgn>822-date</prgn>
9106 </footnote>; it should include the timezone specified
9107 numerically, with the timezone name or abbreviation
9108 optionally present as a comment.
9112 The first "title" line with the package name should start
9113 at the left hand margin; the "trailer" line with the
9114 maintainer and date details should be preceded by exactly
9115 one space. The maintainer details and the date must be
9116 separated by exactly two spaces.
9120 An Emacs mode for editing this format is available: it is
9121 called <tt>debian-changelog-mode</tt>. You can have this
9122 mode selected automatically when you edit a Debian
9123 changelog by adding a local variables clause to the end of
9127 <sect2><heading>Defining alternative changelog formats
9131 It is possible to use a different format to the standard
9132 one, by providing a parser for the format you wish to
9137 In order to have <tt>dpkg-parsechangelog</tt> run your
9138 parser, you must include a line within the last 40 lines
9139 of your file matching the Perl regular expression:
9140 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9141 parentheses should be the name of the format. For
9142 example, you might say:
9144 @@@ changelog-format: joebloggs @@@
9146 Changelog format names are non-empty strings of alphanumerics.
9150 If such a line exists then <tt>dpkg-parsechangelog</tt>
9151 will look for the parser as
9152 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9154 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9155 it is an error for it not to find it, or for it not to
9156 be an executable program. The default changelog format
9157 is <tt>dpkg</tt>, and a parser for it is provided with
9158 the <tt>dpkg</tt> package.
9162 The parser will be invoked with the changelog open on
9163 standard input at the start of the file. It should read
9164 the file (it may seek if it wishes) to determine the
9165 information required and return the parsed information
9166 to standard output in the form of a series of control
9167 fields in the standard format. By default it should
9168 return information about only the most recent version in
9169 the changelog; it should accept a
9170 <tt>-v<var>version</var></tt> option to return changes
9171 information from all versions present <em>strictly
9172 after</em> <var>version</var>, and it should then be an
9173 error for <var>version</var> not to be present in the
9179 <list compact="compact">
9181 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
9184 <p><qref id="versions"><tt>Version</tt></qref> (mandatory)</p>
9188 <qref id="pkg-f-Distribution"><tt>Distribution</tt></qref>
9193 <p><qref id="pkg-f-Urgency"><tt>Urgency</tt></qref> (mandatory)</p>
9197 <qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref>
9202 <p><qref id="pkg-f-Date"><tt>Date</tt></qref></p>
9206 <qref id="pkg-f-Changes"><tt>Changes</tt></qref>
9213 If several versions are being returned (due to the use
9214 of <tt>-v</tt>), the urgency value should be of the
9215 highest urgency code listed at the start of any of the
9216 versions requested followed by the concatenated
9217 (space-separated) comments from all the versions
9218 requested; the maintainer, version, distribution and
9219 date should always be from the most recent version.
9223 For the format of the <tt>Changes</tt> field see <ref
9224 id="pkg-f-Changes">.
9228 If the changelog format which is being parsed always or
9229 almost always leaves a blank line between individual
9230 change notes these blank lines should be stripped out,
9231 so as to make the resulting output compact.
9235 If the changelog format does not contain date or package
9236 name information this information should be omitted from
9237 the output. The parser should not attempt to synthesise
9238 it or find it from other sources.
9242 If the changelog does not have the expected format the
9243 parser should exit with a nonzero exit status, rather
9244 than trying to muddle through and possibly generating
9249 A changelog parser may not interact with the user at
9253 <!-- FIXME: section pkg-srcsubstvars is the same as srcsubstvars -->
9255 <sect1 id="pkg-srcsubstvars"><heading><file>debian/substvars</file>
9256 and variable substitutions
9260 When <prgn>dpkg-gencontrol</prgn>,
9261 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
9262 generate control files they do variable substitutions on
9263 their output just before writing it. Variable
9264 substitutions have the form
9265 <tt>${<var>variable-name</var>}</tt>. The optional file
9266 <file>debian/substvars</file> contains variable substitutions
9267 to be used; variables can also be set directly from
9268 <file>debian/rules</file> using the <tt>-V</tt> option to the
9269 source packaging commands, and certain predefined
9270 variables are available.
9274 This file is usually generated and modified dynamically by
9275 <file>debian/rules</file> targets, in which case it must be
9276 removed by the <tt>clean</tt> target.
9280 See <manref name="dpkg-source" section="1"> for full
9281 details about source variable substitutions, including the
9282 format of <file>debian/substvars</file>.</p>
9285 <sect1><heading><file>debian/files</file>
9289 This file is not a permanent part of the source tree; it
9290 is used while building packages to record which files are
9291 being generated. <prgn>dpkg-genchanges</prgn> uses it
9292 when it generates a <file>.changes</file> file.
9296 It should not exist in a shipped source package, and so it
9297 (and any backup files or temporary files such as
9298 <file>files.new</file>
9300 <file>files.new</file> is used as a temporary file by
9301 <prgn>dpkg-gencontrol</prgn> and
9302 <prgn>dpkg-distaddfile</prgn> - they write a new
9303 version of <file>files</file> here before renaming it,
9304 to avoid leaving a corrupted copy if an error
9306 </footnote>) should be removed by the
9307 <tt>clean</tt> target. It may also be wise to
9308 ensure a fresh start by emptying or removing it at the
9309 start of the <tt>binary</tt> target.
9313 <prgn>dpkg-gencontrol</prgn> adds an entry to this file
9314 for the <file>.deb</file> file that will be created by
9315 <prgn>dpkg-deb</prgn> from the control file that it
9316 generates, so for most packages all that needs to be done
9317 with this file is to delete it in <tt>clean</tt>.
9321 If a package upload includes files besides the source
9322 package and any binary packages whose control files were
9323 made with <prgn>dpkg-gencontrol</prgn> then they should be
9324 placed in the parent of the package's top-level directory
9325 and <prgn>dpkg-distaddfile</prgn> should be called to add
9326 the file to the list in <file>debian/files</file>.</p>
9329 <sect1><heading><file>debian/tmp</file>
9333 This is the canonical temporary location for the
9334 construction of binary packages by the <tt>binary</tt>
9335 target. The directory <file>tmp</file> serves as the root of
9336 the filesystem tree as it is being constructed (for
9337 example, by using the package's upstream makefiles install
9338 targets and redirecting the output there), and it also
9339 contains the <tt>DEBIAN</tt> subdirectory. See <ref
9340 id="pkg-bincreating">.
9344 If several binary packages are generated from the same
9345 source tree it is usual to use several
9346 <file>debian/tmp<var>something</var></file> directories, for
9347 example <file>tmp-a</file> or <file>tmp-doc</file>.
9351 Whatever <file>tmp</file> directories are created and used by
9352 <tt>binary</tt> must of course be removed by the
9353 <tt>clean</tt> target.</p></sect1>
9357 <sect id="pkg-sourcearchives"><heading>Source packages as archives
9361 As it exists on the FTP site, a Debian source package
9362 consists of three related files. You must have the right
9363 versions of all three to be able to use them.
9368 <tag>Debian source control file - <tt>.dsc</tt></tag>
9372 This file contains a series of fields, identified and
9373 separated just like the fields in the control file of
9374 a binary package. The fields are listed below; their
9375 syntax is described above, in <ref id="pkg-controlfields">.
9376 <list compact="compact">
9378 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
9381 <p><qref id="versions"><tt>Version</tt></qref></p>
9384 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
9387 <p><qref id="pkg-f-Binary"><tt>Binary</tt></qref></p>
9390 <p><qref id="pkg-f-Architecture"><tt>Architecture</tt></qref></p>
9394 <qref id="relationships"><tt>Build-Depends</tt> et
9395 al.</qref> (source package interrelationships)
9400 <qref id="pkg-f-Standards-Version"><tt>Standards-Version</tt></qref></p>
9403 <p><qref id="pkg-f-Files"><tt>Files</tt></qref></p>
9408 The source package control file is generated by
9409 <prgn>dpkg-source</prgn> when it builds the source
9410 archive, from other files in the source package,
9411 described above. When unpacking it is checked against
9412 the files and directories in the other parts of the
9413 source package, as described below.</p>
9417 Original source archive -
9419 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
9426 This is a compressed (with <tt>gzip -9</tt>)
9427 <prgn>tar</prgn> file containing the source code from
9428 the upstream authors of the program. The tarfile
9429 unpacks into a directory
9430 <file><var>package</var>-<var>upstream-version</var>.orig</file>,
9431 and does not contain files anywhere other than in
9432 there or in its subdirectories.</p>
9436 Debianisation diff -
9438 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
9444 This is a unified context diff (<tt>diff -u</tt>)
9445 giving the changes which are required to turn the
9446 original source into the Debian source. These changes
9447 may only include editing and creating plain files.
9448 The permissions of files, the targets of symbolic
9449 links and the characteristics of special files or
9450 pipes may not be changed and no files may be removed
9455 All the directories in the diff must exist, except the
9456 <file>debian</file> subdirectory of the top of the source
9457 tree, which will be created by
9458 <prgn>dpkg-source</prgn> if necessary when unpacking.
9462 The <prgn>dpkg-source</prgn> program will
9463 automatically make the <file>debian/rules</file> file
9464 executable (see below).</p></item>
9469 If there is no original source code - for example, if the
9470 package is specially prepared for Debian or the Debian
9471 maintainer is the same as the upstream maintainer - the
9472 format is slightly different: then there is no diff, and the
9474 <file><var>package</var>_<var>version</var>.tar.gz</file> and
9475 contains a directory
9476 <file><var>package</var>-<var>version</var></file>.
9480 <sect><heading>Unpacking a Debian source package without
9481 <prgn>dpkg-source</prgn>
9485 <tt>dpkg-source -x</tt> is the recommended way to unpack a
9486 Debian source package. However, if it is not available it
9487 is possible to unpack a Debian source archive as follows:
9488 <enumlist compact="compact">
9491 Untar the tarfile, which will create a <file>.orig</file>
9495 <p>Rename the <file>.orig</file> directory to
9496 <file><var>package</var>-<var>version</var></file>.</p>
9500 Create the subdirectory <file>debian</file> at the top of
9501 the source tree.</p>
9503 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
9505 <item><p>Untar the tarfile again if you want a copy of the original
9506 source code alongside the Debianised version.</p>
9511 It is not possible to generate a valid Debian source archive
9512 without using <prgn>dpkg-source</prgn>. In particular,
9513 attempting to use <prgn>diff</prgn> directly to generate the
9514 <file>.diff.gz</file> file will not work.
9517 <sect1><heading>Restrictions on objects in source packages
9521 The source package may not contain any hard links
9523 This is not currently detected when building source
9524 packages, but only when extracting
9528 Hard links may be permitted at some point in the
9529 future, but would require a fair amount of
9531 </footnote>, device special files, sockets or setuid or
9534 Setgid directories are allowed.
9539 The source packaging tools manage the changes between the
9540 original and Debianised source using <prgn>diff</prgn> and
9541 <prgn>patch</prgn>. Turning the original source tree as
9542 included in the <file>.orig.tar.gz</file> into the debianised
9543 source must not involve any changes which cannot be
9544 handled by these tools. Problematic changes which cause
9545 <prgn>dpkg-source</prgn> to halt with an error when
9546 building the source package are:
9547 <list compact="compact">
9548 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
9550 <item><p>Changing the targets of symbolic links.</p>
9552 <item><p>Creating directories, other than <file>debian</file>.</p>
9554 <item><p>Changes to the contents of binary files.</p></item>
9555 </list> Changes which cause <prgn>dpkg-source</prgn> to
9556 print a warning but continue anyway are:
9557 <list compact="compact">
9560 Removing files, directories or symlinks.
9562 Renaming a file is not treated specially - it is
9563 seen as the removal of the old file (which
9564 generates a warning, but is otherwise ignored),
9565 and the creation of the new one.
9571 Changed text files which are missing the usual final
9572 newline (either in the original or the modified
9577 Changes which are not represented, but which are not detected by
9578 <prgn>dpkg-source</prgn>, are:
9579 <list compact="compact">
9580 <item><p>Changing the permissions of files (other than
9581 <file>debian/rules</file>) and directories.</p></item>
9586 The <file>debian</file> directory and <file>debian/rules</file>
9587 are handled specially by <prgn>dpkg-source</prgn> - before
9588 applying the changes it will create the <file>debian</file>
9589 directory, and afterwards it will make
9590 <file>debian/rules</file> world-exectuable.
9596 <appendix id="pkg-controlfields"><heading>Control files and their
9597 fields (from old Packaging Manual)
9601 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
9602 data in a common format, known as control files. Binary and
9603 source packages have control data as do the <file>.changes</file>
9604 files which control the installation of uploaded files, and
9605 <prgn>dpkg</prgn>'s internal databases are in a similar
9609 <sect><heading>Syntax of control files
9613 A file consists of one or more paragraphs of fields. The
9614 paragraphs are separated by blank lines. Some control files
9615 only allow one paragraph; others allow several, in which
9616 case each paragraph often refers to a different package.
9620 Each paragraph is a series of fields and values; each field
9621 consists of a name, followed by a colon and the value. It
9622 ends at the end of the line. Horizontal whitespace (spaces
9623 and tabs) may occur before or after the value and is ignored
9624 there; it is conventional to put a single space after the
9629 Some fields' values may span several lines; in this case
9630 each continuation line <em>must</em> start with a space or
9631 tab. Any trailing spaces or tabs at the end of individual
9632 lines of a field value are ignored.
9636 Except where otherwise stated only a single line of data is
9637 allowed and whitespace is not significant in a field body.
9638 Whitespace may never appear inside names (of packages,
9639 architectures, files or anything else), version numbers or
9640 in between the characters of multi-character version
9645 Field names are not case-sensitive, but it is usual to
9646 capitalise the field names using mixed case as shown below.
9650 Blank lines, or lines consisting only of spaces and tabs,
9651 are not allowed within field values or between fields - that
9652 would mean a new paragraph.
9656 It is important to note that there are several fields which
9657 are optional as far as <prgn>dpkg</prgn> and the related
9658 tools are concerned, but which must appear in every Debian
9659 package, or whose omission may cause problems.
9663 <sect><heading>List of fields
9666 <sect1 id="pkg-f-Package"><heading><tt>Package</tt>
9670 The name of the binary package. Package names consist of
9671 the alphanumerics and <tt>+</tt> <tt>-</tt> <tt>.</tt>
9672 (plus, minus and full stop).
9674 The characters <tt>@</tt> <tt>:</tt> <tt>=</tt>
9675 <tt>%</tt> <tt>_</tt> (at, colon, equals, percent
9676 and underscore) used to be legal and are still
9677 accepted when found in a package file, but may not be
9678 used in new packages.
9683 They must be at least two characters and must start with
9684 an alphanumeric. In current versions of dpkg they are
9685 sort of case-sensitive<footnote>
9687 </footnote>; use lowercase package names unless
9688 the package you're building (or referring to, in other
9689 fields) is already using uppercase.
9693 <sect1 id="pkg-f-Version"><heading><tt>Version</tt>
9697 This lists the source or binary package's version number -
9698 see <ref id="versions">.
9703 <sect1 id="pkg-f-Architecture"><heading><tt>Architecture</tt>
9707 This is the architecture string; it is a single word for
9708 the Debian architecture.
9712 <prgn>dpkg</prgn> will check the declared architecture of
9713 a binary package against its own compiled-in value before
9718 The special value <tt>all</tt> indicates that the package
9719 is architecture-independent.
9723 In the main <file>debian/control</file> file in the source
9724 package, or in the source package control file
9725 <file>.dsc</file>, a list of architectures (separated by
9726 spaces) is also allowed, as is the special value
9727 <tt>any</tt>. A list indicates that the source will build
9728 an architecture-dependent package, and will only work
9729 correctly on the listed architectures. <tt>any</tt>
9730 indicates that though the source package isn't dependent
9731 on any particular architecture and should compile fine on
9732 any one, the binary package(s) produced are not
9733 architecture-independent but will instead be specific to
9734 whatever the current build architecture is.
9738 In a <file>.changes</file> file the <tt>Architecture</tt>
9739 field lists the architecture(s) of the package(s)
9740 currently being uploaded. This will be a list; if the
9741 source for the package is being uploaded too the special
9742 entry <tt>source</tt> is also present.
9746 See <ref id="pkg-debianrules"> for information how to get the
9747 architecture for the build process.
9751 <sect1 id="pkg-f-Maintainer"><heading><tt>Maintainer</tt>
9755 The package maintainer's name and email address. The name
9756 should come first, then the email address inside angle
9757 brackets <tt><></tt> (in RFC822 format).
9761 If the maintainer's name contains a full stop then the
9762 whole field will not work directly as an email address due
9763 to a misfeature in the syntax specified in RFC822; a
9764 program using this field as an address must check for this
9765 and correct the problem if necessary (for example by
9766 putting the name in round brackets and moving it to the
9767 end, and bringing the email address forward).
9771 In a <file>.changes</file> file or parsed changelog data this
9772 contains the name and email address of the person
9773 responsible for the particular version in question - this
9774 may not be the package's usual maintainer.
9778 This field is usually optional in as far as the
9779 <prgn>dpkg</prgn> are concerned, but its absence when
9780 building packages usually generates a warning.</p>
9783 <sect1 id="pkg-f-Source"><heading><tt>Source</tt>
9787 This field identifies the source package name.
9791 In a main source control information or a
9792 <file>.changes</file> or <file>.dsc</file> file or parsed
9793 changelog data this may contain only the name of the
9798 In the control file of a binary package (or in a
9799 <file>Packages</file> file) it may be followed by a version
9800 number in parentheses.
9802 It is usual to leave a space after the package name if
9803 a version number is specified.
9804 </footnote> This version number may be omitted (and is, by
9805 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
9806 the <tt>Version</tt> field of the binary package in
9807 question. The field itself may be omitted from a binary
9808 package control file when the source package has the same
9809 name and version as the binary package.
9813 <sect1><heading>Package interrelationship fields:
9814 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
9815 <tt>Recommends</tt> <tt>Suggests</tt>, <tt>Conflicts</tt>,
9816 <tt>Provides</tt>, <tt>Replaces</tt>
9820 These fields describe the package's relationships with
9821 other packages. Their syntax and semantics are described
9822 in <ref id="relationships">.</p>
9825 <sect1 id="pkg-f-Description"><heading><tt>Description</tt>
9829 In a binary package <tt>Packages</tt> file or main source
9830 control file this field contains a description of the
9831 binary package, in a special format. See <ref
9832 id="descriptions"> for details.
9836 In a <file>.changes</file> file it contains a summary of the
9837 descriptions for the packages being uploaded. The part of
9838 the field before the first newline is empty; thereafter
9839 each line has the name of a binary package and the summary
9840 description line from that binary package. Each line is
9841 indented by one space.</p>
9844 <sect1 id="pkg-f-Essential"><heading><tt>Essential</tt>
9848 This is a boolean field which may occur only in the
9849 control file of a binary package (or in the
9850 <file>Packages</file> file) or in a per-package fields
9851 paragraph of a main source control data file.
9855 If set to <tt>yes</tt> then <prgn>dpkg</prgn> and
9856 <prgn>dselect</prgn> will refuse to remove the package
9857 (though it can be upgraded and/or replaced). The other
9858 possible value is <tt>no</tt>, which is the same as not
9859 having the field at all.</p>
9862 <sect1 id="pkg-f-classification"><heading><tt>Section</tt> and
9867 These two fields classify the package. The
9868 <tt>Priority</tt> represents how important that it is that
9869 the user have it installed; the <tt>Section</tt>
9870 represents an application area into which the package has
9875 When they appear in the <file>debian/control</file> file these
9876 fields give values for the section and priority subfields
9877 of the <tt>Files</tt> field of the <file>.changes</file> file,
9878 and give defaults for the section and priority of the
9883 The section and priority are represented, though not as
9884 separate fields, in the information for each file in the
9885 <qref id="pkg-f-Files"><tt>-File</tt></qref>field of a
9886 <file>.changes</file> file. The section value in a
9887 <file>.changes</file> file is used to decide where to install
9888 a package in the FTP archive.
9892 These fields are not used by by <prgn>dpkg</prgn> proper,
9893 but by <prgn>dselect</prgn> when it sorts packages and
9898 These fields can appear in binary package control files,
9899 in which case they provide a default value in case the
9900 <file>Packages</file> files are missing the information.
9901 <prgn>dpkg</prgn> and <prgn>dselect</prgn> will only use
9902 the value from a <file>.deb</file> file if they have no other
9903 information; a value listed in a <file>Packages</file> file
9904 will always take precedence. By default
9905 <prgn>dpkg-gencontrol</prgn> does not include the section
9906 and priority in the control file of a binary package - use
9907 the <tt>-isp</tt>, <tt>-is</tt> or <tt>-ip</tt> options to
9908 achieve this effect.</p>
9911 <sect1 id="pkg-f-Binary"><heading><tt>Binary</tt>
9915 This field is a list of binary packages.
9919 When it appears in the <file>.dsc</file> file it is the list
9920 of binary packages which a source package can produce. It
9921 does not necessarily produce all of these binary packages
9922 for every architecture. The source control file doesn't
9923 contain details of which architectures are appropriate for
9924 which of the binary packages.
9928 When it appears in a <file>.changes</file> file it lists the
9929 names of the binary packages actually being uploaded.
9933 The syntax is a list of binary packages separated by
9936 A space after each comma is conventional.
9937 </footnote> Currently the packages must be separated using
9938 only spaces in the <file>.changes</file> file.</p>
9941 <sect1 id="pkg-f-Installed-Size"><heading><tt>Installed-Size</tt>
9945 This field appears in the control files of binary
9946 packages, and in the <file>Packages</file> files. It gives
9947 the total amount of disk space required to install the
9952 The disk space is represented in kilobytes as a simple
9956 <sect1 id="pkg-f-Files"><heading><tt>Files</tt>
9960 This field contains a list of files with information about
9961 each one. The exact information and syntax varies with
9962 the context. In all cases the part of the field
9963 contents on the same line as the field name is empty. The
9964 remainder of the field is one line per file, each line
9965 being indented by one space and containing a number of
9966 sub-fields separated by spaces.
9970 In the <file>.dsc</file> (Debian source control) file each
9971 line contains the MD5 checksum, size and filename of the
9972 tarfile and (if applicable) diff file which make up the
9973 remainder of the source package.
9975 That is, the parts which are not the <tt>.dsc</tt>.
9976 </footnote> The exact forms of the filenames are described
9977 in <ref id="pkg-sourcearchives">.
9981 In the <file>.changes</file> file this contains one line per
9982 file being uploaded. Each line contains the MD5 checksum,
9983 size, section and priority and the filename. The section
9984 and priority are the values of the corresponding fields in
9985 the main source control file - see <ref
9986 id="pkg-f-classification">. If no section or priority is
9987 specified then <tt>-</tt> should be used, though section
9988 and priority values must be specified for new packages to
9989 be installed properly.
9993 The special value <tt>byhand</tt> for the section in a
9994 <tt>.changes</tt> file indicates that the file in question
9995 is not an ordinary package file and must by installed by
9996 hand by the distribution maintainers. If the section is
9997 <tt>byhand</tt> the priority should be <tt>-</tt>.
10001 If a new Debian revision of a package is being shipped and
10002 no new original source archive is being distributed the
10003 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
10004 entry for the original source archive
10005 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
10006 but the <file>.changes</file> file should leave it out. In
10007 this case the original source archive on the distribution
10008 site must match exactly, byte-for-byte, the original
10009 source archive which was used to generate the
10010 <file>.dsc</file> file and diff which are being uploaded.</p>
10015 id="pkg-f-Standards-Version"><heading><tt>Standards-Version</tt>
10019 The most recent version of the standards (the Debian Policy
10020 and associated texts) with which the package complies. This
10021 is updated manually when editing the source package to
10022 conform to newer standards; it can sometimes be used to
10023 tell when a package needs attention.
10027 Its format is the same as that of a version number except
10028 that no epoch or Debian revision is allowed - see <ref
10029 id="versions">.</p>
10033 <sect1 id="pkg-f-Distribution"><heading><tt>Distribution</tt>
10037 In a <file>.changes</file> file or parsed changelog output
10038 this contains the (space-separated) name(s) of the
10039 distribution(s) where this version of the package should
10040 be or was installed. Distribution names follow the rules
10041 for package names. (See <ref id="pkg-f-Package">).
10045 Current distribution values are:
10047 <tag><em>stable</em></tag>
10050 This is the current "released" version of Debian
10051 GNU/Linux. A new version is released approximately
10052 every 3 months after the <em>development</em> code has
10053 been <em>frozen</em> for a month of testing. Once the
10054 distribution is <em>stable</em> only major bug fixes
10055 are allowed. When changes are made to this
10056 distribution, the release number is increased
10057 (for example: 1.2r1 becomes 1.2r2 then 1.2r3, etc).
10061 <tag><em>unstable</em></tag>
10064 This distribution value refers to the
10065 <em>developmental</em> part of the Debian distribution
10066 tree. New packages, new upstream versions of packages
10067 and bug fixes go into the <em>unstable</em> directory
10068 tree. Download from this distribution at your own
10072 <tag><em>contrib</em></tag>
10075 The packages with this distribution value do not meet
10076 the criteria for inclusion in the main Debian
10077 distribution as defined by the Policy Manual, but meet
10078 the criteria for the <em>contrib</em>
10079 Distribution. There is currently no distinction
10080 between stable and unstable packages in the
10081 <em>contrib</em> or <em>non-free</em>
10082 distributions. Use your best judgement in downloading
10083 from this Distribution.</p>
10086 <tag><em>non-free</em></tag>
10089 Like the packages in the <em>contrib</em> seciton,
10090 the packages in <em>non-free</em> do not meet the
10091 criteria for inclusion in the main Debian distribution
10092 as defined by the Policy Manual. Again, use your best
10093 judgement in downloading from this Distribution.</p>
10095 <tag><em>experimental</em></tag>
10098 The packages with this distribution value are deemed
10099 by their maintainers to be high risk. Oftentimes they
10100 represent early beta or developmental packages from
10101 various sources that the maintainers want people to
10102 try, but are not ready to be a part of the other parts
10103 of the Debian distribution tree. Download at your own
10107 <tag><em>frozen</em></tag>
10110 From time to time, (currently, every 3 months) the
10111 <em>unstable</em> distribution enters a state of
10112 "code-freeze" in anticipation of release as a
10113 <em>stable</em> version. During this period of testing
10114 (usually 4 weeks) only fixes for existing or
10115 newly-discovered bugs will be allowed.
10118 </taglist> You should list <em>all</em> distributions that
10119 the package should be installed into. Except in unusual
10120 circumstances, installations to <em>stable</em> should also
10121 go into <em>frozen</em> (if it exists) and
10122 <em>unstable</em>. Likewise, installations into
10123 <em>frozen</em> should also go into <em>unstable</em>.</p>
10126 <sect1 id="pkg-f-Urgency"><heading><tt>Urgency</tt>
10130 This is a description of how important it is to upgrade to
10131 this version from previous ones. It consists of a single
10132 keyword usually taking one of the values <tt>LOW</tt>,
10133 <tt>MEDIUM</tt> or <tt>HIGH</tt>) followed by an optional
10134 commentary (separated by a space) which is usually in
10135 parentheses. For example:
10137 Urgency: LOW (HIGH for diversions users)
10142 This field appears in the <file>.changes</file> file and in
10143 parsed changelogs; its value appears as the value of the
10144 <tt>urgency</tt> attribute in a <prgn>dpkg</prgn>-style
10145 changelog (see <ref id="pkg-dpkgchangelog">).
10149 Urgency keywords are not case-sensitive.</p>
10152 <sect1 id="pkg-f-Date"><heading><tt>Date</tt>
10156 In <tt>.changes</tt> files and parsed changelogs, this
10157 gives the date the package was built or last edited.</p>
10160 <sect1 id="pkg-f-Format"><heading><tt>Format</tt>
10164 This field occurs in <file>.changes</file> files, and
10165 specifies a format revision for the file. The format
10166 described here is version <tt>1.5</tt>. The syntax of the
10167 format value is the same as that of a package version
10168 number except that no epoch or Debian revision is allowed
10169 - see <ref id="versions">.</p>
10172 <sect1 id="pkg-f-Changes"><heading><tt>Changes</tt>
10176 In a <file>.changes</file> file or parsed changelog this field
10177 contains the human-readable changes data, describing the
10178 differences between the last version and the current one.
10182 There should be nothing in this field before the first
10183 newline; all the subsequent lines must be indented by at
10184 least one space; blank lines must be represented by a line
10185 consiting only of a space and a full stop.
10189 Each version's change information should be preceded by a
10190 "title" line giving at least the version, distribution(s)
10191 and urgency, in a human-readable way.
10195 If data from several versions is being returned the entry
10196 for the most recent version should be returned first, and
10197 entries should be separated by the representation of a
10198 blank line (the "title" line may also be followed by the
10199 representation of blank line).</p>
10202 <sect1 id="pkg-f-Filename">
10203 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10206 These fields in <tt>Packages</tt> files give the
10207 filename(s) of (the parts of) a package in the
10208 distribution directories, relative to the root of the
10209 Debian hierarchy. If the package has been split into
10210 several parts the parts are all listed in order, separated
10215 <sect1 id="pkg-f-Size">
10216 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10219 These fields in <file>Packages</file> files give the size (in
10220 bytes, expressed in decimal) and MD5 checksum of the
10221 file(s) which make(s) up a binary package in the
10222 distribution. If the package is split into several parts
10223 the values for the parts are listed in order, separated by
10228 <sect1 id="pkg-f-Status">
10229 <heading><tt>Status</tt></heading>
10232 This field in <prgn>dpkg</prgn>'s status file records
10233 whether the user wants a package installed, removed or
10234 left alone, whether it is broken (requiring
10235 reinstallation) or not and what its current state on the
10236 system is. Each of these pieces of information is a
10241 <sect1 id="pkg-f-Config-Version">
10242 <heading><tt>Config-Version</tt></heading>
10245 If a package is not installed or not configured, this
10246 field in <prgn>dpkg</prgn>'s status file records the last
10247 version of the package which was successfully
10252 <sect1 id="pkg-f-Conffiles">
10253 <heading><tt>Conffiles</tt></heading>
10256 This field in <prgn>dpkg</prgn>'s status file contains
10257 information about the automatically-managed configuration
10258 files held by a package. This field should <em>not</em>
10259 appear anywhere in a package!
10264 <heading>Obsolete fields</heading>
10267 These are still recognised by <prgn>dpkg</prgn> but should
10268 not appear anywhere any more.
10270 <taglist compact="compact">
10272 <tag><tt>Revision</tt></tag>
10273 <tag><tt>Package-Revision</tt></tag>
10274 <tag><tt>Package_Revision</tt></tag>
10276 The Debian revision part of the package version was
10277 at one point in a separate control file field. This
10278 field went through several names.
10281 <tag><tt>Recommended</tt></tag>
10282 <item>Old name for <tt>Recommends</tt>.</item>
10284 <tag><tt>Optional</tt></tag>
10285 <item>Old name for <tt>Suggests</tt>.</item>
10287 <tag><tt>Class</tt></tag>
10288 <item>Old name for <tt>Priority</tt>.</item>
10297 <appendix id="pkg-conffiles">
10298 <heading>Configuration file handling (from old Packaging Manual)</heading>
10301 <prgn>dpkg</prgn> can do a certain amount of automatic
10302 handling of package configuration files.
10306 Whether this mechanism is appropriate depends on a number of
10307 factors, but basically there are two approaches to any
10308 particular configuration file.
10312 The easy method is to ship a best-effort configuration in the
10313 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10314 handle updates. If the user is unlikely to want to edit the
10315 file, but you need them to be able to without losing their
10316 changes, and a new package with a changed version of the file
10317 is only released infrequently, this is a good approach.
10321 The hard method is to build the configuration file from
10322 scratch in the <prgn>postinst</prgn> script, and to take the
10323 responsibility for fixing any mistakes made in earlier
10324 versions of the package automatically. This will be
10325 appropriate if the file is likely to need to be different on
10329 <sect><heading>Automatic handling of configuration files by
10334 A package may contain a control area file called
10335 <tt>conffiles</tt>. This file should be a list of filenames
10336 of configuration files needing automatic handling, separated
10337 by newlines. The filenames should be absolute pathnames,
10338 and the files referred to should actually exist in the
10343 When a package is upgraded <prgn>dpkg</prgn> will process
10344 the configuration files during the configuration stage,
10345 shortly before it runs the package's <prgn>postinst</prgn>
10350 For each file it checks to see whether the version of the
10351 file included in the package is the same as the one that was
10352 included in the last version of the package (the one that is
10353 being upgraded from); it also compares the version currently
10354 installed on the system with the one shipped with the last
10359 If neither the user nor the package maintainer has changed
10360 the file, it is left alone. If one or the other has changed
10361 their version, then the changed version is preferred - i.e.,
10362 if the user edits their file, but the package maintainer
10363 doesn't ship a different version, the user's changes will
10364 stay, silently, but if the maintainer ships a new version
10365 and the user hasn't edited it the new version will be
10366 installed (with an informative message). If both have
10367 changed their version the user is prompted about the problem
10368 and must resolve the differences themselves.
10372 The comparisons are done by calculating the MD5 message
10373 digests of the files, and storing the MD5 of the file as it
10374 was included in the most recent version of the package.
10378 When a package is installed for the first time
10379 <prgn>dpkg</prgn> will install the file that comes with it,
10380 unless that would mean overwriting a file already on the
10385 However, note that <prgn>dpkg</prgn> will <em>not</em>
10386 replace a conffile that was removed by the user (or by a
10387 script). This is necessary because with some programs a
10388 missing file produces an effect hard or impossible to
10389 achieve in another way, so that a missing file needs to be
10390 kept that way if the user did it.
10394 Note that a package should <em>not</em> modify a
10395 <prgn>dpkg</prgn>-handled conffile in its maintainer
10396 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10397 the user confusing and possibly dangerous options for
10398 conffile update when the package is upgraded.</p>
10401 <sect><heading>Fully-featured maintainer script configuration
10406 For files which contain site-specific information such as
10407 the hostname and networking details and so forth, it is
10408 better to create the file in the package's
10409 <prgn>postinst</prgn> script.
10413 This will typically involve examining the state of the rest
10414 of the system to determine values and other information, and
10415 may involve prompting the user for some information which
10416 can't be obtained some other way.
10420 When using this method there are a couple of important
10421 issues which should be considered:
10425 If you discover a bug in the program which generates the
10426 configuration file, or if the format of the file changes
10427 from one version to the next, you will have to arrange for
10428 the postinst script to do something sensible - usually this
10429 will mean editing the installed configuration file to remove
10430 the problem or change the syntax. You will have to do this
10431 very carefully, since the user may have changed the file,
10432 perhaps to fix the very problem that your script is trying
10433 to deal with - you will have to detect these situations and
10434 deal with them correctly.
10438 If you do go down this route it's probably a good idea to
10439 make the program that generates the configuration file(s) a
10440 separate program in <file>/usr/sbin</file>, by convention called
10441 <file><var>package</var>config</file> and then run that if
10442 appropriate from the post-installation script. The
10443 <tt><var>package</var>config</tt> program should not
10444 unquestioningly overwrite an existing configuration - if its
10445 mode of operation is geared towards setting up a package for
10446 the first time (rather than any arbitrary reconfiguration
10447 later) you should have it check whether the configuration
10448 already exists, and require a <tt>--force</tt> flag to
10449 overwrite it.</p></sect>
10452 <appendix id="pkg-alternatives"><heading>Alternative versions of
10453 an interface - <prgn>update-alternatives</prgn> (from old
10458 When several packages all provide different versions of the
10459 same program or file it is useful to have the system select a
10460 default, but to allow the system administrator to change it
10461 and have their decisions respected.
10465 For example, there are several versions of the <prgn>vi</prgn>
10466 editor, and there is no reason to prevent all of them from
10467 being installed at once, each under their own name
10468 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10469 Nevertheless it is desirable to have the name <tt>vi</tt>
10470 refer to something, at least by default.
10474 If all the packages involved cooperate, this can be done with
10475 <prgn>update-alternatives</prgn>.
10479 Each package provides its own version under its own name, and
10480 calls <prgn>update-alternatives</prgn> in its postinst to
10481 register its version (and again in its prerm to deregister
10486 See the manpage <manref name="update-alternatives"
10487 section="8"> for details.
10491 If <prgn>update-alternatives</prgn> does not seem appropriate
10492 you may wish to consider using diversions instead.</p>
10495 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10496 package's version of a file (from old Packaging Manual)
10500 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10501 when it reinstalls the package it belongs to, and to have it
10502 put the file from the package somewhere else instead.
10506 This can be used locally to override a package's version of a
10507 file, or by one package to override another's version (or
10508 provide a wrapper for it).
10512 Before deciding to use a diversion, read <ref
10513 id="pkg-alternatives"> to see if you really want a diversion
10514 rather than several alternative versions of a program.
10518 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10519 and updated by a special program <prgn>dpkg-divert</prgn>.
10520 Please see <manref name="dpkg-divert" section="8"> for full
10521 details of its operation.
10525 When a package wishes to divert a file from another, it should
10526 call <prgn>dpkg-divert</prgn> in its preinst to add the
10527 diversion and rename the existing file. For example,
10528 supposing that a <prgn>smailwrapper</prgn> package wishes to
10529 install a wrapper around <file>/usr/sbin/smail</file>:
10531 if [ install = "$1" ]; then
10532 dpkg-divert --package smailwrapper --add --rename \
10533 --divert /usr/sbin/smail.real /usr/sbin/smail
10535 </example> Testing <tt>$1</tt> is necessary so that the script
10536 doesn't try to add the diversion again when
10537 <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
10538 smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
10539 copy of <file>/usr/sbin/smail</file> can bypass the diversion and
10540 get installed as the true version.
10544 The postrm has to do the reverse:
10546 if [ remove = "$1" ]; then
10547 dpkg-divert --package smailwrapper --remove --rename \
10548 --divert /usr/sbin/smail.real /usr/sbin/smail
10554 Do not attempt to divert a file which is vitally important for
10555 the system's operation - when using <prgn>dpkg-divert</prgn>
10556 there is a time, after it has been diverted but before
10557 <prgn>dpkg</prgn> has installed the new version, when the file
10558 does not exist.</p>
10563 <!-- vim:set ai et sts=2 sw=2 tw=76: -->