1 <!doctype debiandoc system [
2 <!-- include version information so we don't have to hard code it
3 within the document -->
4 <!entity % versiondata SYSTEM "version.ent"> %versiondata;
10 <title>Debian Policy Manual</title>
11 <author><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 based on their licenses and other restrictions.
293 The aims of this are:
295 <list compact="compact">
296 <item>to allow us to make as much software available as we can</item>
297 <item>to allow us to encourage everyone to write free software,
299 <item>to allow us to make it easy for people to produce
300 CD-ROMs of our system without violating any licenses,
301 import/export restrictions, or any other laws.</item>
306 The <em>main</em> and the <em>non-US/main</em> sections
307 together form the <em>Debian GNU/Linux distribution</em>.
311 Packages in the other sections are not considered to be part
312 of the Debian distribution, although we support their use and
313 provide infrastructure for them (such as our bug-tracking
314 system and mailing lists). This Debian Policy Manual applies
315 to these packages as well.
319 <heading>The Debian Free Software Guidelines</heading>
321 The Debian Free Software Guidelines (DFSG) form our
322 definition of "free software". These are:
324 <tag>Free Redistribution
327 The license of a Debian component may not restrict any
328 party from selling or giving away the software as a
329 component of an aggregate software distribution
330 containing programs from several different
331 sources. The license may not require a royalty or
332 other fee for such sale.
337 The program must include source code, and must allow
338 distribution in source code as well as compiled form.
343 The license must allow modifications and derived
344 works, and must allow them to be distributed under the
345 same terms as the license of the original software.
347 <tag>Integrity of The Author's Source Code
350 The license may restrict source-code from being
351 distributed in modified form <em>only</em> if the
352 license allows the distribution of "patch files"
353 with the source code for the purpose of modifying the
354 program at build time. The license must explicitly
355 permit distribution of software built from modified
356 source code. The license may require derived works to
357 carry a different name or version number from the
358 original software. (This is a compromise. The Debian
359 Project encourages all authors to not restrict any
360 files, source or binary, from being modified.)
362 <tag>No Discrimination Against Persons or Groups
365 The license must not discriminate against any person
368 <tag>No Discrimination Against Fields of Endeavor
371 The license must not restrict anyone from making use
372 of the program in a specific field of endeavor. For
373 example, it may not restrict the program from being
374 used in a business, or from being used for genetic
377 <tag>Distribution of License
380 The rights attached to the program must apply to all
381 to whom the program is redistributed without the need
382 for execution of an additional license by those
385 <tag>License Must Not Be Specific to Debian
388 The rights attached to the program must not depend on
389 the program's being part of a Debian system. If the
390 program is extracted from Debian and used or
391 distributed without Debian but otherwise within the
392 terms of the program's license, all parties to whom
393 the program is redistributed must have the same
394 rights as those that are granted in conjunction with
397 <tag>License Must Not Contaminate Other Software
400 The license must not place restrictions on other
401 software that is distributed along with the licensed
402 software. For example, the license must not insist
403 that all other programs distributed on the same medium
404 must be free software.
406 <tag>Example Licenses
409 The "GPL," "BSD," and "Artistic" licenses are examples of
410 licenses that we consider <em>free</em>.
417 <heading>Sections</heading>
420 <heading>The main section</heading>
423 Every package in <em>main</em> and <em>non-US/main</em>
424 must comply with the DFSG (Debian Free Software
429 In addition, the packages in <em>main</em>
430 <list compact="compact">
432 must not require a package outside of <em>main</em>
433 for compilation or execution (thus, the package must
434 not declare a "Depends", "Recommends", or
435 "Build-Depends" relationship on a non-<em>main</em>
439 must not be so buggy that we refuse to support them,
443 must meet all policy requirements presented in this
450 Similarly, the packages in <em>non-US/main</em>
451 <list compact="compact">
453 must not require a package outside of <em>main</em>
454 or <em>non-US/main</em> for compilation or
458 must not be so buggy that we refuse to support them,
461 must meet all policy requirements presented in this
470 <heading>The contrib section</heading>
473 Every package in <em>contrib</em> and
474 <em>non-US/contrib</em> must comply with the DFSG.
478 In addition, the packages in <em>contrib</em> and
479 <em>non-US/contrib</em>
480 <list compact="compact">
482 must not be so buggy that we refuse to support them,
486 must meet all policy requirements presented in this
493 Furthermore, packages in <em>contrib</em> must not require
494 a package in a <em>non-US</em> section for compilation or
499 Examples of packages which would be included in
500 <em>contrib</em> or <em>non-US/contrib</em> are:
501 <list compact="compact">
503 free packages which require <em>contrib</em>,
504 <em>non-free</em> packages or packages which are not
505 in our archive at all for compilation or execution,
509 wrapper packages or other sorts of free accessories for
516 <sect1 id="non-free">
517 <heading>The non-free section</heading>
520 Packages must be placed in <em>non-free</em> or
521 <em>non-US/non-free</em> if they are not compliant with
522 the DFSG or are encumbered by patents or other legal
523 issues that make their distribution problematic.
527 In addition, the packages in <em>non-free</em> and
528 <em>non-US/non-free</em>
529 <list compact="compact">
531 must not be so buggy that we refuse to support them,
535 must meet all policy requirements presented in this
536 manual that it is possible for them to meet.
538 It is possible that there are policy
539 requirements which the package is unable to
540 meet, for example, if the source is
541 unavailable. These situations will need to be
542 handled on a case-by-case basis.
550 <heading>The non-US sections</heading>
553 Non-free programs with cryptographic program code need to
554 be stored on the <em>non-us</em> server because of export
555 restrictions of the U.S.
559 Programs which use patented algorithms that have a
560 restricted license also need to be stored on "non-us",
561 since that is located in a country where it is not allowed
562 to patent algorithms.
566 A package depends on another package which is distributed
567 via the non-us server has to be stored on the non-us
573 <sect id="pkgcopyright">
574 <heading>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).
584 We reserve the right to restrict files from being included
585 anywhere in our archives if
586 <list compact="compact">
588 their use or distribution would break a law,
591 there is an ethical conflict in their distribution or
595 we would have to sign a license for them, or
598 their distribution would conflict with other project
605 Programs whose authors encourage the user to make
606 donations are fine for the main distribution, provided
607 that the authors do not claim that not donating is
608 immoral, unethical, illegal or something similar; in such
609 a case they must go in <em>non-free</em>.
613 Packages whose copyright permission notices (or patent
614 problems) do not even allow redistribution of binaries
615 only, and where no special permission has been obtained,
616 must not be placed on the Debian FTP site and its mirrors
621 Note that under international copyright law (this applies
622 in the United States, too), <em>no</em> distribution or
623 modification of a work is allowed without an explicit
624 notice saying so. Therefore a program without a copyright
625 notice <em>is</em> copyrighted and you may not do anything
626 to it without risking being sued! Likewise if a program
627 has a copyright notice but no statement saying what is
628 permitted then nothing is permitted.
632 Many authors are unaware of the problems that restrictive
633 copyrights (or lack of copyright notices) can cause for
634 the users of their supposedly-free software. It is often
635 worthwhile contacting such authors diplomatically to ask
636 them to modify their license terms. However, this can be a
637 politically difficult thing to do and you should ask for
638 advice on the <tt>debian-legal</tt> mailing list first, as
643 When in doubt about a copyright, send mail to
644 <email>debian-legal@lists.debian.org</email>. Be prepared
645 to provide us with the copyright statement. Software
646 covered by the GPL, public domain software and BSD-like
647 copyrights are safe; be wary of the phrases "commercial
648 use prohibited" and "distribution restricted".
652 <sect id="subsections">
653 <heading>Subsections</heading>
656 The packages in the sections <em>main</em>,
657 <em>contrib</em> and <em>non-free</em> are grouped further
658 into <em>subsections</em> to simplify handling.
662 The section and subsection for each package should be
663 specified in the package's <tt>Section</tt> control
664 record (see <ref id="f-Section">).
665 However, the maintainer of the Debian archive
666 may override this selection to ensure the consistency of
667 the Debian distribution. The <tt>Section</tt> field
668 should be of the form:
669 <list compact="compact">
671 <em>subsection</em> if the package is in the
672 <em>main</em> section,
675 <em>section/subsection</em> if the package is in
676 the <em>contrib</em> or <em>non-free</em> section,
680 <tt>non-US</tt>, <tt>non-US/contrib</tt> or
681 <tt>non-US/non-free</tt> if the package is in
682 <em>non-US/main</em>, <em>non-US/contrib</em> or
683 <em>non-US/non-free</em> respectively.
689 The Debian archive maintainers provide the authoritative
690 list of subsections. At present, they are:
691 <em>admin</em>, <em>base</em>, <em>comm</em>,
692 <em>contrib</em>, <em>devel</em>, <em>doc</em>,
693 <em>editors</em>, <em>electronics</em>, <em>embedded</em>,
694 <em>games</em>, <em>gnome</em> <em>graphics</em>,
695 <em>hamradio</em>, <em>interpreters</em>, <em>kde</em>,
696 <em>libs</em>, <em>libdevel</em>, <em>mail</em>,
697 <em>math</em>, <em>misc</em>, <em>net</em>, <em>news</em>,
698 <em>non-US</em>, <em>non-free</em>, <em>oldlibs</em>,
699 <em>otherosfs</em>, <em>perl</em>, <em>python</em>
700 <em>science</em>, <em>shells</em>,
701 <em>sound</em>, <em>tex</em>, <em>text</em>,
702 <em>utils</em>, <em>web</em>, <em>x11</em>.
706 <sect id="priorities">
707 <heading>Priorities</heading>
710 Each package should have a <em>priority</em> value, which is
711 included in the package's <em>control record</em>
712 (see <ref id="f-Priority">).
713 This information is used by the Debian package management tools to
714 separate high-priority packages from less-important packages.
718 The following <em>priority levels</em> are recognised by the
719 Debian package management tools.
721 <tag><tt>required</tt></tag>
723 Packages which are necessary for the proper
724 functioning of the system. You must not remove these
725 packages or your system may become totally broken and
726 you may not even be able to use <prgn>dpkg</prgn> to
727 put things back. Systems with only the
728 <tt>required</tt> packages are probably unusable, but
729 they do have enough functionality to allow the
730 sysadmin to boot and install more software.
732 <tag><tt>important</tt></tag>
734 Important programs, including those which one would
735 expect to find on any Unix-like system. If the
736 expectation is that an experienced Unix person who
737 found it missing would say "What on earth is going on,
738 where is <prgn>foo</prgn>?", it must be an
739 <tt>important</tt> package.<footnote>
740 This is an important criterion because we are
741 trying to produce, amongst other things, a free
744 Other packages without which the system will not run
745 well or be usable must also have priority
746 <tt>important</tt>. This does
747 <em>not</em> include Emacs, the X Window System, TeX
748 or any other large applications. The
749 <tt>important</tt> packages are just a bare minimum of
750 commonly-expected and necessary tools.
752 <tag><tt>standard</tt></tag>
754 These packages provide a reasonably small but not too
755 limited character-mode system. This is what will be
756 installed by default if the user doesn't select anything
757 else. It doesn't include many large applications.
759 <tag><tt>optional</tt></tag>
761 (In a sense everything that isn't required is
762 optional, but that's not what is meant here.) This is
763 all the software that you might reasonably want to
764 install if you didn't know what it was and don't have
765 specialized requirements. This is a much larger system
766 and includes the X Window System, a full TeX
767 distribution, and many applications. Note that
768 optional packages should not conflict with each other.
770 <tag><tt>extra</tt></tag>
772 This contains all packages that conflict with others
773 with required, important, standard or optional
774 priorities, or are only likely to be useful if you
775 already know what they are or have specialised
782 Packages must not depend on packages with lower priority
783 values (excluding build-time dependencies). In order to
784 ensure this, the priorities of one or more packages may need
793 <heading>Binary packages</heading>
796 The Debian GNU/Linux distribution is based on the Debian
797 package management system, called <prgn>dpkg</prgn>. Thus,
798 all packages in the Debian distribution must be provided
799 in the <tt>.deb</tt> file format.
803 <heading>The package name</heading>
806 Every package must have a name that's unique within the Debian
811 The package name is included in the control field
812 <tt>Package</tt>, the format of which is described
813 in <ref id="f-Package">.
814 The package name is also included as a part of the file name
815 of the <tt>.deb</tt> file.
820 <heading>The version of a package</heading>
823 Every package has a version number recorded in its
824 <tt>Version</tt> control file field, described in
825 <ref id="f-Version">.
829 The package management system imposes an ordering on version
830 numbers, so that it can tell whether packages are being up- or
831 downgraded and so that package system front end applications
832 can tell whether a package it finds available is newer than
833 the one installed on the system. The version number format
834 has the most significant parts (as far as comparison is
835 concerned) at the beginning.
839 If an upstream package has problematic version numbers they
840 should be converted to a sane form for use in the
841 <tt>Version</tt> field.
845 <heading>Version numbers based on dates</heading>
848 In general, Debian packages should use the same version
849 numbers as the upstream sources.
853 However, in some cases where the upstream version number is
854 based on a date (e.g., a development "snapshot" release) the
855 package management system cannot handle these version
856 numbers without epochs. For example, dpkg will consider
857 "96May01" to be greater than "96Dec24".
861 To prevent having to use epochs for every new upstream
862 version, the version number should be changed to the
863 following format in such cases: "19960501", "19961224". It
864 is up to the maintainer whether he/she wants to bother the
865 upstream maintainer to change the version numbers upstream,
870 Note that other version formats based on dates which are
871 parsed correctly by the package management system should
872 <em>not</em> be changed.
876 Native Debian packages (i.e., packages which have been
877 written especially for Debian) whose version numbers include
878 dates should always use the "YYYYMMDD" format.
885 <heading>The maintainer of a package</heading>
888 Every package must have a Debian maintainer (the
889 maintainer may be one person or a group of people
890 reachable from a common email address, such as a mailing
891 list). The maintainer is responsible for ensuring that
892 the package is placed in the appropriate distributions.
896 The maintainer must be specified in the
897 <tt>Maintainer</tt> control field with their correct name
898 and a working email address. If one person maintains
899 several packages, he/she should try to avoid having
900 different forms of their name and email address in
901 the <tt>Maintainer</tt> fields of those packages.
905 The format of the <tt>Maintainer</tt> control field is
906 described in <ref id="f-Maintainer">.
910 If the maintainer of a package quits from the Debian
911 project, "Debian QA Group"
912 <email>packages@qa.debian.org</email> takes over the
913 maintainership of the package until someone else
914 volunteers for that task. These packages are called
915 <em>orphaned packages</em>.<footnote>
916 The detailed procedure for doing this gracefully can
917 be found in the Debian Developer's Reference,
918 see <ref id="related">.
923 <sect id="descriptions">
924 <heading>The description of a package</heading>
927 Every Debian package must have an extended description
928 stored in the appropriate field of the control record.
929 The technical information about the format of the
930 <tt>Description</tt> field is in <ref id="f-Description">.
934 The description should describe the package (the program) to a
935 user (system administrator) who has never met it before so that
936 they have enough information to decide whether they want to
937 install it. This description should not just be copied verbatim
938 from the program's documentation.
942 Put important information first, both in the synopsis and
943 extended description. Sometimes only the first part of the
944 synopsis or of the description will be displayed. You can
945 assume that there will usually be a way to see the whole
946 extended description.
950 The description should also give information about the
951 significant dependencies and conflicts between this package
952 and others, so that the user knows why these dependencies and
953 conflicts have been declared.
957 Instructions for configuring or using the package should
958 not be included (that is what installation scripts,
959 manual pages, info files, etc., are for). Copyright
960 statements and other administrivia should not be included
961 either (that is what the copyright file is for).
964 <sect1 id="synopsis"><heading>The single line synopsis</heading>
967 The single line synopsis should be kept brief - certainly
972 Do not include the package name in the synopsis line. The
973 display software knows how to display this already, and you
974 do not need to state it. Remember that in many situations
975 the user may only see the synopsis line - make it as
976 informative as you can.
981 <sect1 id="extendeddesc"><heading>The extended description</heading>
984 Do not try to continue the single line synopsis into the
985 extended description. This will not work correctly when
986 the full description is displayed, and makes no sense
987 where only the summary (the single line synopsis) is
992 The extended description should describe what the package
993 does and how it relates to the rest of the system (in terms
994 of, for example, which subsystem it is which part of).
998 The description field needs to make sense to anyone, even
999 people who have no idea about any of the things the
1000 package deals with.<footnote>
1001 The blurb that comes with a program in its
1002 announcements and/or <prgn>README</prgn> files is
1003 rarely suitable for use in a description. It is
1004 usually aimed at people who are already in the
1005 community where the package is used.
1014 <heading>Dependencies</heading>
1017 Every package must specify the dependency information
1018 about other packages that are required for the first to
1023 For example, a dependency entry must be provided for any
1024 shared libraries required by a dynamically-linked executable
1025 binary in a package.
1029 Packages are not required to declare any dependencies they
1030 have on other packages which are marked <tt>Essential</tt>
1031 (see below), and should not do so unless they depend on a
1032 particular version of that package.
1036 Sometimes, a package requires another package to be installed
1037 <em>and</em> configured before it can be installed. In this
1038 case, you must specify a <tt>Pre-Depends</tt> entry for
1043 You should not specify a <tt>Pre-Depends</tt> entry for a
1044 package before this has been discussed on the
1045 <tt>debian-devel</tt> mailing list and a consensus about
1046 doing that has been reached.
1050 The format of the package interrelationship control fields is
1051 described in <ref id="relationships">.
1055 <sect id="virtual_pkg">
1056 <heading>Virtual packages</heading>
1059 Sometimes, there are several packages which offer
1060 more-or-less the same functionality. In this case, it's
1061 useful to define a <em>virtual package</em> whose name
1062 describes that common functionality. (The virtual
1063 packages only exist logically, not physically; that's why
1064 they are called <em>virtual</em>.) The packages with this
1065 particular function will then <em>provide</em> the virtual
1066 package. Thus, any other package requiring that function
1067 can simply depend on the virtual package without having to
1068 specify all possible packages individually.
1072 All packages should use virtual package names where
1073 appropriate, and arrange to create new ones if necessary.
1074 They should not use virtual package names (except privately,
1075 amongst a cooperating group of packages) unless they have
1076 been agreed upon and appear in the list of virtual package
1077 names. (See also <ref id="virtual">)
1081 The latest version of the authoritative list of virtual
1082 package names can be found in the <tt>debian-policy</tt> package.
1083 It is also available from the Debian web mirrors at
1084 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1085 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>
1086 and from the Debian archive mirrors at
1087 <tt><url name="/doc/package-developer/virtual-package-names-list.txt"
1088 id="http://ftp.debian.org/debian/doc/package-developer/virtual-package-names-list.txt"></tt>.
1092 The procedure for updating the list is described in the preface
1099 <heading>Base system</heading>
1102 The <tt>base system</tt> is a minimum subset of the Debian
1103 GNU/Linux system that is installed before everything else
1104 on a new system. Thus, only very few packages are allowed
1105 to go into the <tt>base</tt> section to keep the required
1106 disk usage very small.
1110 Most of these packages will have the priority value
1111 <tt>required</tt> or at least <tt>important</tt>, and many
1112 of them will be tagged <tt>essential</tt> (see below).
1117 <heading>Essential packages</heading>
1120 Some packages are tagged <tt>essential</tt> for a system
1121 using the <tt>Essential</tt> control file field.
1122 The format of the <tt>Essential</tt> control field is
1123 described in <ref id="f-Essential">.
1127 Since these packages cannot be easily removed (one has to
1128 specify an extra <em>force option</em> to
1129 <prgn>dpkg</prgn> to do so), this flag must not be used
1130 unless absolutely necessary. A shared library package
1131 must not be tagged <tt>essential</tt>; dependencies will
1132 prevent its premature removal, and we need to be able to
1133 remove it when it has been superseded.
1137 Since dpkg will not prevent upgrading of other packages
1138 while an <tt>essential</tt> package is in an unconfigured
1139 state, all <tt>essential</tt> packages must supply all of
1140 their core functionality even when unconfigured. If the
1141 package cannot satisfy this requirement it must not be
1142 tagged as essential, and any packages depending on this
1143 package must instead have explicit dependency fields as
1148 You must not tag any packages <tt>essential</tt> before
1149 this has been discussed on the <tt>debian-devel</tt>
1150 mailing list and a consensus about doing that has been
1156 <heading>Tasks</heading>
1159 The Debian install process allows the user to choose from
1160 a number of common tasks which a Debian system can be used to
1161 perform. Selecting a task with <prgn>tasksel</prgn> causes
1162 a set of packages that are useful in performing that task to be
1167 This set of packages is all available packages which have the
1168 name of the selected task in the <tt>Task</tt> field of their
1169 control file. The format of this field is a list of tasks,
1170 separated by commas.
1174 You should not tag any packages as belonging to a task
1175 before this has been discussed on the
1176 <em>debian-devel</em> mailing list and a consensus about
1177 doing that has been reached.
1181 For third parties (and historical reasons), tasksel also
1182 supports constructing tasks based on <em>task
1183 packages</em>. These are packages whose names begin with
1184 <em>task-</em>. Task packages should not be included in the
1189 <sect id="maintscripts">
1190 <heading>Maintainer Scripts</heading>
1193 The package installation scripts should avoid producing
1194 output which it is unnecessary for the user to see and
1195 should rely on <prgn>dpkg</prgn> to stave off boredom on
1196 the part of a user installing many packages. This means,
1197 amongst other things, using the <tt>--quiet</tt> option on
1198 <prgn>install-info</prgn>.
1202 Errors which occur during the execution of an installation
1203 script must be checked and the installation must not
1204 continue after an error.
1208 Note that in general <ref id="scripts"> applies to package
1209 maintainer scripts, too.
1213 You should not use <prgn>dpkg-divert</prgn> on a file
1214 belonging to another package without consulting the
1215 maintainer of that package first.
1219 All packages which supply an instance of a common command
1220 name (or, in general, filename) should generally use
1221 <prgn>update-alternatives</prgn>, so that they may be
1222 installed together. If <prgn>update-alternatives</prgn>
1223 is not used, then each package must use
1224 <tt>Conflicts</tt> to ensure that other packages are
1225 de-installed. (In this case, it may be appropriate to
1226 specify a conflict against earlier versions of something
1227 that previously did not use
1228 <prgn>update-alternatives</prgn>; this is an exception to
1229 the usual rule that versioned conflicts should be
1233 <sect1 id="maintscriptprompt">
1234 <heading>Prompting in maintainer scripts</heading>
1236 Package maintainer scripts may prompt the user if
1237 necessary. Prompting may be accomplished by hand<footnote>
1238 From the Jargon file: by hand 2. By extension,
1239 writing code which does something in an explicit or
1240 low-level way for which a presupplied library
1241 (<em>debconf, in this instance</em>) routine ought
1242 to have been available.
1244 (but this is deprecated), or by communicating through a program
1245 which conforms to the Debian Configuration management
1246 specification, version 2 or higher, such as
1247 <prgn>debconf</prgn><footnote>
1249 6% of Debian packages [see <url
1250 id="http://ftp-master.debian.org/~joeyh/debconf-stats/"
1251 name="Debconf stats">] currently use
1252 <package>debconf</package> to prompt the user at
1253 install time, and this number is growing daily. The
1254 benefits of using debconf are briefly explained at
1255 <url id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"
1256 name="Debconf introduction">; they include
1257 preconfiguration, (mostly) noninteractive
1258 installation, elimination of redundant prompting,
1259 consistency of user interface, etc.
1263 With this increasing number of packages using
1264 <package>debconf</package>, plus the existence of a
1265 nascent second implementation of the Debian
1266 configuration management system
1267 (<package>cdebconf</package>), and the stabilization
1268 of the protocol these things use, the time has
1269 finally come to reflect the use of these things in
1276 The Debian Configuration management specification is included
1277 in the <file>debconf_specification</file> files in the
1278 <package>debian-policy</package> package.
1279 It is also available from the Debian web mirrors at
1280 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1281 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>
1282 and from the Debian archive mirrors at
1283 <tt><url name="/doc/package-developer/debconf_specification.txt.gz"
1284 id="http://ftp.debian.org/debian/doc/package-developer/debconf_specification.txt.gz"></tt>.
1288 Packages which use the Debian Configuration management
1289 specification may contain an additional
1290 <prgn>config</prgn> script and a <tt>templates</tt>
1291 file in their control archive<footnote>
1292 The control.tar.gz inside the .deb.
1293 See <manref name="deb" section="5">.
1295 The <prgn>config</prgn> script might be run before the
1296 <prgn>preinst</prgn> script, and before the package is unpacked
1297 or any of its dependencies or pre-dependancies are satisfied.
1298 Therefore it must work using only the tools present in
1299 <em>essential</em> packages.<footnote>
1300 <package>Debconf</package> or another tool that
1301 implements the Debian Configuration management
1302 specification will also be installed, and any
1303 versioned dependencies on it will be satisfied
1304 before preconfiguration begins.
1309 Packages should try to minimize the amount of prompting
1310 they need to do, and they should ensure that the user
1311 will only ever be asked each question once. This means
1312 that packages should try to use appropriate shared
1313 configuration files (such as <file>/etc/papersize</file> and
1314 <file>/etc/news/server</file>), and shared
1315 <package>debconf</package> variables rather than each
1316 prompting for their own list of required pieces of
1321 It also means that an upgrade should not ask the same
1322 questions again, unless the user has used
1323 <tt>dpkg --purge</tt> to remove the package's configuration.
1324 The answers to configuration questions should be stored in an
1325 appropriate place in <file>/etc</file> so that the user can
1326 modify them, and how this has been done should be
1331 If a package has a vitally important piece of
1332 information to pass to the user (such as "don't run me
1333 as I am, you must edit the following configuration files
1334 first or you risk your system emitting badly-formatted
1335 messages"), it should display this in the
1336 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1337 prompt the user to hit return to acknowledge the
1338 message. Copyright messages do not count as vitally
1339 important (they belong in
1340 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1341 neither do instructions on how to use a program (these
1342 should be in on-line documentation, where all the users
1347 Any necessary prompting should almost always be confined
1348 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1349 script. If it is done in the <prgn>postinst</prgn>, it
1350 should be protected with a conditional so that
1351 unnecessary prompting doesn't happen if a package's
1352 installation fails and the <prgn>postinst</prgn> is
1353 called with <tt>abort-upgrade</tt>,
1354 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1364 <heading>Source packages</heading>
1366 <sect id="standardsversion">
1367 <heading>Standards conformance</heading>
1370 Source packages should specify the most recent version number
1371 of this policy document with which your package complied
1372 when it was last updated.
1376 This information may be used to file bug reports
1377 automatically if your package becomes too much out of date.
1381 The version is specified in the <tt>Standards-Version</tt>
1383 The format of the <tt>Standards-Version</tt> field is
1384 described in <ref id="f-Standards-Version">.
1388 You should regularly, and especially if your package has
1389 become out of date, check for the newest Policy Manual
1390 available and update your package, if necessary. When your
1391 package complies with the new standards you should update the
1392 <tt>Standards-Version</tt> source package field and
1393 release it.<footnote>
1394 See the file <file>upgrading-checklist</file> for
1395 information about policy which has changed between
1396 different versions of this document.
1402 <sect id="pkg-relations">
1403 <heading>Package relationships</heading>
1406 Source packages should specify which binary packages they
1407 require to be installed or not to be installed in order to
1408 build correctly. For example, if building a package
1409 requires a certain compiler, then the compiler should be
1410 specified as a build-time dependency.
1414 It is not necessary to explicitly specify build-time
1415 relationships on a minimal set of packages that are always
1416 needed to compile, link and put in a Debian package a
1417 standard "Hello World!" program written in C or C++. The
1418 required packages are called <em>build-essential</em>, and
1419 an informational list can be found in
1420 <file>/usr/share/doc/build-essential/list</file> (which is
1421 contained in the <tt>build-essential</tt>
1424 <list compact="compact">
1426 This allows maintaining the list separately
1427 from the policy documents (the list does not
1428 need the kind of control that the policy
1432 Having a separate package allows one to install
1433 the build-essential packages on a machine, as
1434 well as allowing other packages such as tasks to
1435 require installation of the build-essential
1436 packages using the depends relation.
1439 The separate package allows bug reports against
1440 the list to be categorized separately from
1441 the policy management process in the BTS.
1448 When specifying the set of build-time dependencies, one
1449 should list only those packages explicitly required by the
1450 build. It is not necessary to list packages which are
1451 required merely because some other package in the list of
1452 build-time dependencies depends on them.<footnote>
1453 The reason for this is that dependencies change, and
1454 you should list all those packages, and <em>only</em>
1455 those packages that <em>you</em> need directly. What
1456 others need is their business. For example, if you
1457 only link against <file>libimlib</file>, you will need to
1458 build-depend on <package>libimlib2-dev</package> but
1459 not against any <tt>libjpeg*</tt> packages, even
1460 though <tt>libimlib2-dev</tt> currently depends on
1461 them: installation of <package>libimlib2-dev</package>
1462 will automatically ensure that all of its run-time
1463 dependencies are satisfied.
1468 If build-time dependencies are specified, it must be
1469 possible to build the package and produce working binaries
1470 on a system with only essential and build-essential
1471 packages installed and also those required to satisfy the
1472 build-time relationships (including any implied
1473 relationships). In particular, this means that version
1474 clauses should be used rigorously in build-time
1475 relationships so that one cannot produce bad or
1476 inconsistently configured packages when the relationships
1477 are properly satisfied.
1481 <ref id="relationships"> explains the technical details.
1486 <heading>Changes to the upstream sources</heading>
1489 If changes to the source code are made that are not
1490 specific to the needs of the Debian system, they should be
1491 sent to the upstream authors in whatever form they prefer
1492 so as to be included in the upstream version of the
1497 If you need to configure the package differently for
1498 Debian or for Linux, and the upstream source doesn't
1499 provide a way to do so, you should add such configuration
1500 facilities (for example, a new <prgn>autoconf</prgn> test
1501 or <tt>#define</tt>) and send the patch to the upstream
1502 authors, with the default set to the way they originally
1503 had it. You can then easily override the default in your
1504 <file>debian/rules</file> or wherever is appropriate.
1508 You should make sure that the <prgn>configure</prgn> utility
1509 detects the correct architecture specification string
1510 (refer to <ref id="arch-spec"> for details).
1514 If you need to edit a <prgn>Makefile</prgn> where
1515 GNU-style <prgn>configure</prgn> scripts are used, you
1516 should edit the <file>.in</file> files rather than editing the
1517 <prgn>Makefile</prgn> directly. This allows the user to
1518 reconfigure the package if necessary. You should
1519 <em>not</em> configure the package and edit the generated
1520 <prgn>Makefile</prgn>! This makes it impossible for
1521 someone else to later reconfigure the package.
1526 <sect id="dpkgchangelog">
1527 <heading>Debian changelog: <file>debian/changelog</file></heading>
1530 Changes in the Debian version of the package should be
1531 briefly explained in the Debian changelog file
1532 <file>debian/changelog</file>. This includes modifications
1533 made in the Debian package compared to the upstream one
1534 as well as other changes and updates to the package.
1536 Although there is nothing stopping an author who is also
1537 the Debian maintainer from using this changelog for all
1538 their changes, it will have to be renamed if the Debian
1539 and upstream maintainers become different people. In such
1540 a case, however, it might be better to maintain the package
1541 as a non-native package.
1546 Mistakes in changelogs are usually best rectified by making
1547 a new changelog entry rather than "rewriting history" by
1548 editing old changelog entries.
1552 The format of the <file>debian/changelog</file> allows the
1553 package building tools to discover which version of the package
1554 is being built and find out other release-specific information.
1558 That format is a series of entries like this:
1560 <example compact="compact">
1561 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1563 [optional blank line(s), stripped]
1565 * <var>change details</var>
1566 <var>more change details</var>
1568 [blank line(s), included in output of dpkg-parsechangelog]
1570 * <var>even more change details</var>
1572 [optional blank line(s), stripped]
1574 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1579 <var>package</var> and <var>version</var> are the source
1580 package name and version number.
1584 <var>distribution(s)</var> lists the distributions where
1585 this version should be installed when it is uploaded - it
1586 is copied to the <tt>Distribution</tt> field in the
1587 <file>.changes</file> file. See <ref id="f-Distribution">.
1591 <var>urgency</var> is the value for the <tt>Urgency</tt>
1592 field in the <file>.changes</file> file for the upload
1593 (see <ref id="f-Urgency">). It is not possible to specify
1594 an urgency containing commas; commas are used to separate
1595 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1596 <prgn>dpkg</prgn> changelog format (though there is
1597 currently only one useful <var>keyword</var>,
1598 <tt>urgency</tt>).<footnote>
1599 Recognised urgency values are <tt>low</tt>,
1600 <tt>medium</tt>, <tt>high</tt> and <tt>emergency</tt>.
1601 They have an effect on how quickly a package will be
1602 considered for inclusion into the <tt>testing</tt>
1603 distribution, and give an indication of the importance
1604 of any fixes included in this upload.
1609 The change details may in fact be any series of lines
1610 starting with at least two spaces, but conventionally each
1611 change starts with an asterisk and a separating space and
1612 continuation lines are indented so as to bring them in
1613 line with the start of the text above. Blank lines may be
1614 used here to separate groups of changes, if desired.
1618 If this upload resolves bugs recorded in the Bug Tracking
1619 System (BTS), they may be automatically closed on the
1620 inclusion of this package into the Debian archive by
1621 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1622 in the change details.<footnote>
1623 To be precise, the string should match the following
1624 Perl regular expression:
1626 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1628 Then all of the bug numbers listed will be closed by the
1629 archive maintenance script (<prgn>katie</prgn>), or in
1630 the case of an NMU, marked as fixed.
1632 This information is conveyed via the <tt>Closes</tt> field
1633 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1637 The maintainer name and email address used in the changelog
1638 should be the details of the person uploading <em>this</em>
1639 version. They are <em>not</em> necessarily those of the
1640 usual package maintainer. The information here will be
1641 copied to the <tt>Changed-By</tt> field in the
1642 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1643 and then later used to send an acknowledgement when the
1644 upload has been installed.
1648 The <var>date</var> should be in RFC822 format<footnote>
1649 This is generated by the <prgn>822-date</prgn>
1651 </footnote>; it should include the time zone specified
1652 numerically, with the time zone name or abbreviation
1653 optionally present as a comment in parentheses.
1657 The first "title" line with the package name should start
1658 at the left hand margin; the "trailer" line with the
1659 maintainer and date details should be preceded by exactly
1660 one space. The maintainer details and the date must be
1661 separated by exactly two spaces.
1665 For more information on placement of the changelog files
1666 within binary packages, please see <ref id="changelogs">.
1669 <sect1><heading>Alternative changelog formats</heading>
1672 In non-experimental packages you must use a format for
1673 <file>debian/changelog</file> which is supported by the most
1674 recent released version of <prgn>dpkg</prgn>.
1678 It is possible to use a format different from the standard
1679 one by providing a changelog parser for the format you wish
1680 to use. The parser must have an API compatible with that
1681 expected by <prgn>dpkg-genchanges</prgn> and
1682 <prgn>dpkg-gencontrol</prgn>, and it must not interact with
1685 If there is general interest in the new format, you should
1686 contact the <package>dpkg</package> maintainer to have the
1687 parser script for it included in the <prgn>dpkg</prgn>
1688 package. (You will need to agree that the parser and its
1689 manpage may be distributed under the GNU GPL, just as the rest
1690 of <prgn>dpkg</prgn> is.)
1697 <heading>Error trapping in makefiles</heading>
1700 When <prgn>make</prgn> invokes a command in a makefile
1701 (including your package's upstream makefiles and
1702 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1703 means that <prgn>sh</prgn>'s usual bad error handling
1704 properties apply: if you include a miniature script as one
1705 of the commands in your makefile you'll find that if you
1706 don't do anything about it then errors are not detected
1707 and <prgn>make</prgn> will blithely continue after
1712 Every time you put more than one shell command (this
1713 includes using a loop) in a makefile command you
1714 must make sure that errors are trapped. For
1715 simple compound commands, such as changing directory and
1716 then running a program, using <tt>&&</tt> rather
1717 than semicolon as a command separator is sufficient. For
1718 more complex commands including most loops and
1719 conditionals you should include a separate <tt>set -e</tt>
1720 command at the start of every makefile command that's
1721 actually one of these miniature shell scripts.
1725 <sect id="timestamps">
1726 <heading>Time Stamps</heading>
1728 Maintainers should preserve the modification times of the
1729 upstream source files in a package, as far as is reasonably
1731 The rationale is that there is some information conveyed
1732 by knowing the age of the file, for example, you could
1733 recognize that some documentation is very old by looking
1734 at the modification time, so it would be nice if the
1735 modification time of the upstream source would be
1741 <sect id="restrictions">
1742 <heading>Restrictions on objects in source packages</heading>
1745 The source package may not contain any hard links<footnote>
1747 This is not currently detected when building source
1748 packages, but only when extracting
1752 Hard links may be permitted at some point in the
1753 future, but would require a fair amount of
1756 </footnote>, device special files, sockets or setuid or
1757 setgid files.<footnote>
1758 Setgid directories are allowed.
1763 <sect id="debianrules">
1764 <heading>Main building script: <file>debian/rules</file></heading>
1767 This file must be an executable makefile, and contains the
1768 package-specific recipes for compiling the package and
1769 building binary package(s) from the source.
1773 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1774 so that it can be invoked by saying its name rather than
1775 invoking <prgn>make</prgn> explicitly.
1779 Since an interactive <file>debian/rules</file> script makes it
1780 impossible to auto-compile that package and also makes it
1781 hard for other people to reproduce the same binary
1782 package, all <em>required targets</em> MUST be
1783 non-interactive. At a minimum, required targets are the
1784 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1785 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1786 <em>binary-indep</em>, and <em>build</em>. It also follows
1787 that any target that these targets depend on must also be
1792 The targets are as follows (required unless stated otherwise):
1794 <tag><tt>build</tt></tag>
1797 The <tt>build</tt> target should perform all the
1798 configuration and compilation of the package.
1799 If a package has an interactive pre-build
1800 configuration routine, the Debianized source package
1801 must either be built after this has taken place (so
1802 that the binary package can be built without rerunning
1803 the configuration) or the configuration routine
1804 modified to become non-interactive. (The latter is
1805 preferable if there are architecture-specific features
1806 detected by the configuration routine.)
1810 For some packages, notably ones where the same
1811 source tree is compiled in different ways to produce
1812 two binary packages, the <tt>build</tt> target
1813 does not make much sense. For these packages it is
1814 good enough to provide two (or more) targets
1815 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1816 for each of the ways of building the package, and a
1817 <tt>build</tt> target that does nothing. The
1818 <tt>binary</tt> target will have to build the
1819 package in each of the possible ways and make the
1820 binary package out of each.
1824 The <tt>build</tt> target must not do anything
1825 that might require root privilege.
1829 The <tt>build</tt> target may need to run the
1830 <tt>clean</tt> target first - see below.
1834 When a package has a configuration and build routine
1835 which takes a long time, or when the makefiles are
1836 poorly designed, or when <tt>build</tt> needs to
1837 run <tt>clean</tt> first, it is a good idea to
1838 <tt>touch build</tt> when the build process is
1839 complete. This will ensure that if <tt>debian/rules
1840 build</tt> is run again it will not rebuild the whole
1842 Another common way to do this is for <tt>build</tt>
1843 to depend on <prgn>build-stamp</prgn> and to do
1844 nothing else, and for the <prgn>build-stamp</prgn>
1845 target to do the building and to <tt>touch
1846 build-stamp</tt> on completion. This is
1847 especially useful if the build routine creates a
1848 file or directory called <tt>build</tt>; in such a
1849 case, <tt>build</tt> will need to be listed as
1850 a phony target (i.e., as a dependency of the
1851 <tt>.PHONY</tt> target). See the documentation of
1852 <prgn>make</prgn> for more information on phony
1858 <tag><tt>build-arch</tt> (optional),
1859 <tt>build-indep</tt> (optional)
1863 A package may also provide both of the targets
1864 <tt>build-arch</tt> and <tt>build-indep</tt>.
1865 The <tt>build-arch</tt> target, if provided, should
1866 perform all the configuration and compilation required
1867 for producing all architecture-dependant binary packages
1868 (those packages for which the body of the
1869 <tt>Architecture</tt> field in <tt>debian/control</tt>
1870 is not <tt>all</tt>).
1871 Similarly, the <tt>build-indep</tt> target, if
1872 provided, should perform all the configuration and
1873 compilation required for producing all
1874 architecture-independent binary packages
1875 (those packages for which the body of the
1876 <tt>Architecture</tt> field in <tt>debian/control</tt>
1878 The <tt>build</tt> target should depend on those of the
1879 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1880 are provided in the rules file.
1884 If one or both of the targets <tt>build-arch</tt> and
1885 <tt>build-indep</tt> are not provided, then invoking
1886 <file>debian/rules</file> with one of the not-provided
1887 targets as arguments should produce a exit status code
1888 of 2. Usually this is provided automatically by make
1889 if the target is missing.
1893 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1894 must not do anything that might require root privilege.
1898 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1899 <tt>binary-indep</tt>
1903 The <tt>binary</tt> target must be all that is
1904 necessary for the user to build the binary package(s)
1905 produced from this source package. It is
1906 split into two parts: <prgn>binary-arch</prgn> builds
1907 the binary packages which are specific to a particular
1908 architecture, and <tt>binary-indep</tt> builds
1909 those which are not.
1912 <tt>binary</tt> may be (and commonly is) a target with
1913 no commands which simply depends on
1914 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1917 Both <tt>binary-*</tt> targets should depend on the
1918 <tt>build</tt> target, or on the appropriate
1919 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1920 provided, so that the package is built if it has not
1921 been already. It should then create the relevant
1922 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1923 make their control files and <prgn>dpkg-deb</prgn> to
1924 build them and place them in the parent of the top
1929 Both the <tt>binary-arch</tt> and
1930 <tt>binary-indep</tt> targets <em>must</em> exist.
1931 If one of them has nothing to do (which will always be
1932 the case if the source generates only a single binary
1933 package, whether architecture-dependent or not), it
1934 must still exist and must always succeed.
1938 The <tt>binary</tt> targets must be invoked as
1940 The <prgn>fakeroot</prgn> package often allows one
1941 to build a package correctly even without being
1947 <tag><tt>clean</tt></tag>
1950 This must undo any effects that the <tt>build</tt>
1951 and <tt>binary</tt> targets may have had, except
1952 that it should leave alone any output files created in
1953 the parent directory by a run of a <tt>binary</tt>
1958 If a <tt>build</tt> file is touched at the end of
1959 the <tt>build</tt> target, as suggested above, it
1960 should be removed as the first action that
1961 <tt>clean</tt> performs, so that running
1962 <tt>build</tt> again after an interrupted
1963 <tt>clean</tt> doesn't think that everything is
1968 The <tt>clean</tt> target may need to be
1969 invoked as root if <tt>binary</tt> has been
1970 invoked since the last <tt>clean</tt>, or if
1971 <tt>build</tt> has been invoked as root (since
1972 <tt>build</tt> may create directories, for
1977 <tag><tt>get-orig-source</tt> (optional)</tag>
1980 This target fetches the most recent version of the
1981 original source package from a canonical archive site
1982 (via FTP or WWW, for example), does any necessary
1983 rearrangement to turn it into the original source
1984 tar file format described below, and leaves it in the
1989 This target may be invoked in any directory, and
1990 should take care to clean up any temporary files it
1995 This target is optional, but providing it if
1996 possible is a good idea.
2002 The <tt>build</tt>, <tt>binary</tt> and
2003 <tt>clean</tt> targets must be invoked with the current
2004 directory being the package's top-level directory.
2009 Additional targets may exist in <file>debian/rules</file>,
2010 either as published or undocumented interfaces or for the
2011 package's internal use.
2015 The architectures we build on and build for are determined
2016 by <prgn>make</prgn> variables using the utility
2017 <qref id="pkg-dpkgarch"><prgn>dpkg-architecture</prgn></qref>.
2018 You can determine the
2019 Debian architecture and the GNU style architecture
2020 specification string for the build machine (the machine type
2021 we are building on) as well as for the host machine (the
2022 machine type we are building for). Here is a list of
2023 supported <prgn>make</prgn> variables:
2024 <list compact="compact">
2026 <tt>DEB_*_ARCH</tt> (the Debian architecture)
2029 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2030 specification string)
2033 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2034 <tt>DEB_*_GNU_TYPE</tt>)
2037 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2038 <tt>DEB_*_GNU_TYPE</tt>)
2040 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2041 the build machine or <tt>HOST</tt> for specification of the
2046 Backward compatibility can be provided in the rules file
2047 by setting the needed variables to suitable default
2048 values; please refer to the documentation of
2049 <prgn>dpkg-architecture</prgn> for details.
2053 It is important to understand that the <tt>DEB_*_ARCH</tt>
2054 string only determines which Debian architecture we are
2055 building on or for. It should not be used to get the CPU
2056 or system information; the GNU style variables should be
2061 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2062 <sect id="substvars">
2063 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2066 When <prgn>dpkg-gencontrol</prgn>,
2067 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2068 generate control files they perform variable substitutions
2069 on their output just before writing it. Variable
2070 substitutions have the form <tt>${<var>variable</var>}</tt>.
2071 The optional file <file>debian/substvars</file> contains
2072 variable substitutions to be used; variables can also be set
2073 directly from <file>debian/rules</file> using the <tt>-V</tt>
2074 option to the source packaging commands, and certain
2075 predefined variables are also available.
2079 The <file>debian/substvars</file> file is usually generated and
2080 modified dynamically by <file>debian/rules</file> targets, in
2081 which case it must be removed by the <tt>clean</tt> target.
2085 See <manref name="dpkg-source" section="1"> for full
2086 details about source variable substitutions, including the
2087 format of <file>debian/substvars</file>.</p>
2090 <sect id="debianfiles">
2091 <heading>Generated files list: <file>debian/files</file></heading>
2094 This file is not a permanent part of the source tree; it
2095 is used while building packages to record which files are
2096 being generated. <prgn>dpkg-genchanges</prgn> uses it
2097 when it generates a <file>.changes</file> file.
2101 It should not exist in a shipped source package, and so it
2102 (and any backup files or temporary files such as
2103 <file>files.new</file><footnote>
2104 <file>files.new</file> is used as a temporary file by
2105 <prgn>dpkg-gencontrol</prgn> and
2106 <prgn>dpkg-distaddfile</prgn> - they write a new
2107 version of <tt>files</tt> here before renaming it,
2108 to avoid leaving a corrupted copy if an error
2110 </footnote>) should be removed by the
2111 <tt>clean</tt> target. It may also be wise to
2112 ensure a fresh start by emptying or removing it at the
2113 start of the <tt>binary</tt> target.
2117 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2118 package, it adds an entry to <file>debian/files</file> for the
2119 <file>.deb</file> file that will be created when <tt>dpkg-deb
2120 --build</tt> is run for that binary package. So for most
2121 packages all that needs to be done with this file is to
2122 delete it in the <tt>clean</tt> target.
2126 If a package upload includes files besides the source
2127 package and any binary packages whose control files were
2128 made with <prgn>dpkg-gencontrol</prgn> then they should be
2129 placed in the parent of the package's top-level directory
2130 and <prgn>dpkg-distaddfile</prgn> should be called to add
2131 the file to the list in <file>debian/files</file>.</p>
2137 <chapt id="controlfields">
2138 <heading>Control files and their fields</heading>
2141 The package management system manipulates data represented in
2142 a common format, known as <em>control data</em>, stored in
2143 <em>control files</em>.
2144 Control files are used for source packages, binary packages and
2145 the <file>.changes</file> files which control the installation
2146 of uploaded files<footnote>
2147 <prgn>dpkg</prgn>'s internal databases are in a similar
2152 <sect id="controlsyntax">
2153 <heading>Syntax of control files</heading>
2156 A control file consists of one or more paragraphs of
2158 The paragraphs are also sometimes referred to as stanzas.
2160 The paragraphs are separated by blank lines. Some control
2161 files allow only one paragraph; others allow several, in
2162 which case each paragraph usually refers to a different
2163 package. (For example, in source packages, the first
2164 paragraph refers to the source package, and later paragraphs
2165 refer to binary packages generated from the source.)
2169 Each paragraph consists of a series of data fields; each
2170 field consists of the field name, followed by a colon and
2171 then the data/value associated with that field. It ends at
2172 the end of the line. Horizontal whitespace (spaces and
2173 tabs) may occur immediately before or after the value and is
2174 ignored there; it is conventional to put a single space
2175 after the colon. For example, a field might be:
2176 <example compact="compact">
2179 the field name is <tt>Package</tt> and the field value
2184 Some fields' values may span several lines; in this case
2185 each continuation line must start with a space or a tab.
2186 Any trailing spaces or tabs at the end of individual
2187 lines of a field value are ignored.
2191 Except where otherwise stated, only a single line of data is
2192 allowed and whitespace is not significant in a field body.
2193 Whitespace must not appear inside names (of packages,
2194 architectures, files or anything else) or version numbers,
2195 or between the characters of multi-character version
2200 Field names are not case-sensitive, but it is usual to
2201 capitalize the field names using mixed case as shown below.
2205 Blank lines, or lines consisting only of spaces and tabs,
2206 are not allowed within field values or between fields - that
2207 would mean a new paragraph.
2212 <sect id="sourcecontrolfiles">
2213 <heading>Source package control files -- <file>debian/control</file></heading>
2216 The <file>debian/control</file> file contains the most vital
2217 (and version-independent) information about the source package
2218 and about the binary packages it creates.
2222 The first paragraph of the control file contains information about
2223 the source package in general. The subsequent sets each describe a
2224 binary package that the source tree builds.
2228 The fields in the general paragraph (the first one, for the source
2231 <list compact="compact">
2232 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2233 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2234 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2235 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2236 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2237 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2242 The fields in the binary package paragraphs are:
2244 <list compact="compact">
2245 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2246 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2247 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2248 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2249 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2250 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2251 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2256 The syntax and semantics of the fields are described below.
2262 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2263 generate control files for binary packages (see below), by
2264 <prgn>dpkg-genchanges</prgn> to generate the
2265 <tt>.changes</tt> file to accompany the upload, and by
2266 <prgn>dpkg-source</prgn> when it creates the <file>.dsc</file>
2267 source control file as part of a source archive.
2271 The fields here may contain variable references - their
2272 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2273 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2274 when they generate output control files.
2275 See <ref id="substvars"> for details.
2280 <sect id="binarycontrolfiles">
2281 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2284 The <file>DEBIAN/control</file> file contains the most vital
2285 (and version-dependent) information about a binary package.
2289 The fields in this file are:
2291 <list compact="compact">
2292 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2293 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2294 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2295 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2296 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2297 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2298 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2299 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2300 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2301 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2302 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2307 <sect id="debiansourcecontrolfiles">
2308 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2311 This file contains a series of fields, identified and
2312 separated just like the fields in the control file of
2313 a binary package. The fields are listed below; their
2314 syntax is described above, in <ref id="pkg-controlfields">.
2316 <list compact="compact">
2317 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2318 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2319 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2320 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2321 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2322 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2323 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2324 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2329 The source package control file is generated by
2330 <prgn>dpkg-source</prgn> when it builds the source
2331 archive, from other files in the source package,
2332 described above. When unpacking, it is checked against
2333 the files and directories in the other parts of the
2339 <sect id="debianchangesfiles">
2340 <heading>Debian changes files -- <file>.changes</file></heading>
2343 The .changes files are used by the Debian archive maintenance
2344 software to process updates to packages. They contain one
2345 paragraph which contains information from the
2346 <tt>debian/control</tt> file and other data about the
2347 source package gathered via <tt>debian/changelog</tt>
2348 and <tt>debian/rules</tt>.
2352 The fields in this file are:
2354 <list compact="compact">
2355 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2356 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2357 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2358 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2359 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2360 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2361 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2362 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2363 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2364 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2365 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2366 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2367 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2368 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2373 <sect id="controlfieldslist">
2374 <heading>List of fields</heading>
2376 <sect1 id="f-Source">
2377 <heading><tt>Source</tt></heading>
2380 This field identifies the source package name.
2384 In a main source control information, a <file>.changes</file>
2385 or a <file>.dsc</file> file this may contain only the name
2386 of the source package.
2390 In the control file of a binary package it may be followed
2391 by a version number in parentheses<footnote>
2392 It is customary to leave a space after the package name
2393 if a version number is specified.
2395 This version number may be omitted (and is, by
2396 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2397 the <tt>Version</tt> field of the binary package in
2398 question. The field itself may be omitted from a binary
2399 package control file when the source package has the same
2400 name and version as the binary package.
2404 <sect1 id="f-Maintainer">
2405 <heading><tt>Maintainer</tt></heading>
2408 The package maintainer's name and email address. The name
2409 should come first, then the email address inside angle
2410 brackets <tt><></tt> (in RFC822 format).
2414 If the maintainer's name contains a full stop then the
2415 whole field will not work directly as an email address due
2416 to a misfeature in the syntax specified in RFC822; a
2417 program using this field as an address must check for this
2418 and correct the problem if necessary (for example by
2419 putting the name in round brackets and moving it to the
2420 end, and bringing the email address forward).
2424 <sect1 id="f-Changed-By">
2425 <heading><tt>Changed-By</tt></heading>
2428 The name and email address of the person who changed the
2429 said package. Usually the name of the maintainer.
2430 All the rules for the Maintainer field apply here, too.
2434 <sect1 id="f-Section">
2435 <heading><tt>Section</tt></heading>
2438 This field specifies an application area into which the package
2439 has been classified. See <ref id="subsections">.
2443 When it appears in the <file>debian/control</file> file,
2444 it gives the value for the subfield of the same name in
2445 the <tt>Files</tt> field of the <file>.changes</file> file.
2446 It also gives the default for the same field in the binary
2451 By default, <prgn>dpkg-gencontrol</prgn> does not include this
2452 field in the control file of a binary package - use the
2453 <tt>-is</tt> (or <tt>-isp</tt>) options to achieve this effect.
2457 <sect1 id="f-Priority">
2458 <heading><tt>Priority</tt></heading>
2461 This field represents how important that it is that the user
2462 have the package installed. See <ref id="priorities">.
2466 When it appears in the <file>debian/control</file> file,
2467 it gives the value for the subfield of the same name in
2468 the <tt>Files</tt> field of the <file>.changes</file> file.
2469 It also gives the default for the same field in the binary
2474 By default, <prgn>dpkg-gencontrol</prgn> does not include this
2475 field in the control file of a binary package - use the
2476 <tt>-ip</tt> (or <tt>-isp</tt>) options to achieve this effect.
2480 <sect1 id="f-Package">
2481 <heading><tt>Package</tt></heading>
2484 The name of the binary package.
2488 Package names must consist only of lower case letters
2489 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
2490 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
2491 They must be at least two characters long and must start
2492 with an alphanumeric character.
2496 <sect1 id="f-Architecture">
2497 <heading><tt>Architecture</tt></heading>
2500 This is the architecture string; it is a single word for
2501 the Debian architecture. The special value <tt>all</tt>
2502 indicates that the package is architecture-independent.
2506 In the main <file>debian/control</file> file in the source
2507 package, or in the source package control file
2508 <file>.dsc</file>, a list of architectures (separated by
2509 spaces) is also allowed, as is the special value
2510 <tt>any</tt>. A list indicates that the source will build
2511 an architecture-dependent package, and will only work
2512 correctly on the listed architectures. <tt>any</tt>
2513 indicates that though the source package isn't dependent
2514 on any particular architecture and should compile fine on
2515 any one, the binary package(s) produced are not
2516 architecture-independent but will instead be specific to
2517 whatever the current build architecture is.
2521 In a <file>.changes</file> file the <tt>Architecture</tt>
2522 field lists the architecture(s) of the package(s)
2523 currently being uploaded. This will be a list; if the
2524 source for the package is being uploaded too the special
2525 entry <tt>source</tt> is also present.
2529 See <ref id="debianrules"> for information how to get the
2530 architecture for the build process.
2534 <sect1 id="f-Essential">
2535 <heading><tt>Essential</tt></heading>
2538 This is a boolean field which may occur only in the
2539 control file of a binary package or in a per-package fields
2540 paragraph of a main source control data file.
2544 If set to <tt>yes</tt> then the package management system
2545 will refuse to remove the package (upgrading and replacing
2546 it is still possible). The other possible value is <tt>no</tt>,
2547 which is the same as not having the field at all.
2552 <heading>Package interrelationship fields:
2553 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2554 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Conflicts</tt>,
2555 <tt>Provides</tt>, <tt>Replaces</tt>
2559 These fields describe the package's relationships with
2560 other packages. Their syntax and semantics are described
2561 in <ref id="relationships">.</p>
2564 <sect1 id="f-Standards-Version">
2565 <heading><tt>Standards-Version</tt></heading>
2568 The most recent version of the standards (the policy
2569 manual and associated texts) with which the package
2574 The version number has four components: major and minor
2575 version number and major and minor patch level. When the
2576 standards change in a way that requires every package to
2577 change the major number will be changed. Significant
2578 changes that will require work in many packages will be
2579 signaled by a change to the minor number. The major patch
2580 level will be changed for any change to the meaning of the
2581 standards, however small; the minor patch level will be
2582 changed when only cosmetic, typographical or other edits
2583 are made which neither change the meaning of the document
2584 nor affect the contents of packages.
2588 Thus only the first three components of the policy version
2589 are significant in the <em>Standards-Version</em> control
2590 field, and so either these three components or the all
2591 four components may be specified.<footnote>
2592 In the past, people specified the full version number
2593 in the Standards-Version field, for example "2.3.0.0".
2594 Since minor patch-level changes don't introduce new
2595 policy, it was thought it would be better to relax
2596 policy and only require the first 3 components to be
2597 specified, in this example "2.3.0". All four
2598 components may still be used if someone wishes to do so.
2604 <sect1 id="f-Version">
2605 <heading><tt>Version</tt></heading>
2608 The version number of a package. The format is:
2609 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2613 The three components here are:
2615 <tag><var>epoch</var></tag>
2618 This is a single (generally small) unsigned integer. It
2619 may be omitted, in which case zero is assumed. If it is
2620 omitted then the <var>upstream_version</var> may not
2625 It is provided to allow mistakes in the version numbers
2626 of older versions of a package, and also a package's
2627 previous version numbering schemes, to be left behind.
2631 <tag><var>upstream_version</var></tag>
2634 This is the main part of the version number. It is
2635 usually the version number of the original ("upstream")
2636 package from which the <file>.deb</file> file has been made,
2637 if this is applicable. Usually this will be in the same
2638 format as that specified by the upstream author(s);
2639 however, it may need to be reformatted to fit into the
2640 package management system's format and comparison
2645 The comparison behavior of the package management system
2646 with respect to the <var>upstream_version</var> is
2647 described below. The <var>upstream_version</var>
2648 portion of the version number is mandatory.
2652 The <var>upstream_version</var> may contain only
2653 alphanumerics<footnote>
2654 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2656 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2657 <tt>:</tt> (full stop, plus, hyphen, colon) and should
2658 start with a digit. If there is no
2659 <var>debian_revision</var> then hyphens are not allowed;
2660 if there is no <var>epoch</var> then colons are not
2665 <tag><var>debian_revision</var></tag>
2668 This part of the version number specifies the version of
2669 the Debian package based on the upstream version. It
2670 may contain only alphanumerics and the characters
2671 <tt>+</tt> and <tt>.</tt> (plus and full stop) and is
2672 compared in the same way as the
2673 <var>upstream_version</var> is.
2677 It is optional; if it isn't present then the
2678 <var>upstream_version</var> may not contain a hyphen.
2679 This format represents the case where a piece of
2680 software was written specifically to be turned into a
2681 Debian package, and so there is only one "debianization"
2682 of it and therefore no revision indication is required.
2686 It is conventional to restart the
2687 <var>debian_revision</var> at <tt>1</tt> each time the
2688 <var>upstream_version</var> is increased.
2692 The package management system will break the version
2693 number apart at the last hyphen in the string (if there
2694 is one) to determine the <var>upstream_version</var> and
2695 <var>debian_revision</var>. The absence of a
2696 <var>debian_revision</var> compares earlier than the
2697 presence of one (but note that the
2698 <var>debian_revision</var> is the least significant part
2699 of the version number).
2706 The <var>upstream_version</var> and <var>debian_revision</var>
2707 parts are compared by the package management system using the
2712 The strings are compared from left to right.
2716 First the initial part of each string consisting entirely of
2717 non-digit characters is determined. These two parts (one of
2718 which may be empty) are compared lexically. If a difference
2719 is found it is returned. The lexical comparison is a
2720 comparison of ASCII values modified so that all the letters
2721 sort earlier than all the non-letters.
2725 Then the initial part of the remainder of each string which
2726 consists entirely of digit characters is determined. The
2727 numerical values of these two parts are compared, and any
2728 difference found is returned as the result of the comparison.
2729 For these purposes an empty string (which can only occur at
2730 the end of one or both version strings being compared) counts
2735 These two steps (comparing and removing initial non-digit
2736 strings and initial digit strings) are repeated until a
2737 difference is found or both strings are exhausted.
2741 Note that the purpose of epochs is to allow us to leave behind
2742 mistakes in version numbering, and to cope with situations
2743 where the version numbering scheme changes. It is
2744 <em>not</em> intended to cope with version numbers containing
2745 strings of letters which the package management system cannot
2746 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
2747 silly orderings (the author of this manual has heard of a
2748 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
2749 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
2750 <tt>2</tt> and so forth).
2754 <sect1 id="f-Description">
2755 <heading><tt>Description</tt></heading>
2758 In a source or binary control file, the <tt>Description</tt>
2759 field contains a description of the binary package, consisting
2760 of two parts, the synopsis or the short description, and the
2761 long description. The field's format is as follows:
2766 Description: <single line synopsis>
2767 <extended description over several lines>
2772 The lines in the extended description can have these formats:
2778 Those starting with a single space are part of a paragraph.
2779 Successive lines of this form will be word-wrapped when
2780 displayed. The leading space will usually be stripped off.
2784 Those starting with two or more spaces. These will be
2785 displayed verbatim. If the display cannot be panned
2786 horizontally, the displaying program will linewrap them "hard"
2787 (i.e., without taking account of word breaks). If it can they
2788 will be allowed to trail off to the right. None, one or two
2789 initial spaces may be deleted, but the number of spaces
2790 deleted from each line will be the same (so that you can have
2791 indenting work correctly, for example).
2795 Those containing a single space followed by a single full stop
2796 character. These are rendered as blank lines. This is the
2797 <em>only</em> way to get a blank line<footnote>
2798 Completely empty lines will not be rendered as blank lines.
2799 Instead, they will cause the parser to think you're starting
2800 a whole new record in the control file, and will therefore
2801 likely abort with an error.
2806 Those containing a space, a full stop and some more characters.
2807 These are for future expansion. Do not use them.
2813 Do not use tab characters. Their effect is not predictable.
2817 See <ref id="descriptions"> for further information on this.
2821 In a <file>.changes</file> file, the <tt>Description</tt> field
2822 contains a summary of the descriptions for the packages being
2827 The part of the field before the first newline is empty;
2828 thereafter each line has the name of a binary package and
2829 the summary description line from that binary package.
2830 Each line is indented by one space.
2835 <sect1 id="f-Distribution">
2836 <heading><tt>Distribution</tt></heading>
2839 In a <file>.changes</file> file or parsed changelog output
2840 this contains the (space-separated) name(s) of the
2841 distribution(s) where this version of the package should
2842 be installed. Valid distributions are determined by the
2843 archive maintainers.<footnote>
2844 Current distribution names are:
2845 <taglist compact="compact">
2846 <tag><em>stable</em></tag>
2848 This is the current "released" version of Debian
2849 GNU/Linux. Once the distribution is
2850 <em>stable</em> only security fixes and other
2851 major bug fixes are allowed. When changes are
2852 made to this distribution, the release number is
2853 increased (for example: 2.2r1 becomes 2.2r2 then
2857 <tag><em>unstable</em></tag>
2859 This distribution value refers to the
2860 <em>developmental</em> part of the Debian
2861 distribution tree. New packages, new upstream
2862 versions of packages and bug fixes go into the
2863 <em>unstable</em> directory tree. Download from
2864 this distribution at your own risk.
2867 <tag><em>testing</em></tag>
2869 This distribution value refers to the
2870 <em>testing</em> part of the Debian distribution
2871 tree. It receives its packages from the
2872 unstable distribution after a short time lag to
2873 ensure that there are no major issues with the
2874 unstable packages. It is less prone to breakage
2875 than unstable, but still risky. It is not
2876 possible to upload packages directly to
2880 <tag><em>frozen</em></tag>
2882 From time to time, the <em>testing</em>
2883 distribution enters a state of "code-freeze" in
2884 anticipation of release as a <em>stable</em>
2885 version. During this period of testing only
2886 fixes for existing or newly-discovered bugs will
2887 be allowed. The exact details of this stage are
2888 determined by the Release Manager.
2891 <tag><em>experimental</em></tag>
2893 The packages with this distribution value are
2894 deemed by their maintainers to be high
2895 risk. Oftentimes they represent early beta or
2896 developmental packages from various sources that
2897 the maintainers want people to try, but are not
2898 ready to be a part of the other parts of the
2899 Debian distribution tree. Download at your own
2905 You should list <em>all</em> distributions that the
2906 package should be installed into.
2910 More information is available in the Debian Developer's
2911 Reference, section "The Debian archive".
2918 <heading><tt>Date</tt></heading>
2921 This field includes the date the package was built or last edited.
2925 The value of this field is usually extracted from the
2926 <file>debian/changelog</file> file - see
2927 <ref id="dpkgchangelog">).
2931 <sect1 id="f-Format">
2932 <heading><tt>Format</tt></heading>
2935 This field specifies a format revision for the file.
2936 The most current format described in the Policy Manual
2937 is version <strong>1.5</strong>. The syntax of the
2938 format value is the same as that of a package version
2939 number except that no epoch or Debian revision is allowed
2940 - see <ref id="f-Version">.
2944 <sect1 id="f-Urgency">
2945 <heading><tt>Urgency</tt></heading>
2948 This is a description of how important it is to upgrade to
2949 this version from previous ones. It consists of a single
2950 keyword usually taking one of the values <tt>low</tt>,
2951 <tt>medium</tt> or <tt>high</tt> (not case-sensitive)
2952 followed by an optional commentary (separated by a space)
2953 which is usually in parentheses. For example:
2956 Urgency: low (HIGH for users of diversions)
2962 The value of this field is usually extracted from the
2963 <file>debian/changelog</file> file - see
2964 <ref id="dpkgchangelog">.
2968 <sect1 id="f-Changes">
2969 <heading><tt>Changes</tt></heading>
2972 This field contains the human-readable changes data, describing
2973 the differences between the last version and the current one.
2977 There should be nothing in this field before the first
2978 newline; all the subsequent lines must be indented by at
2979 least one space; blank lines must be represented by a line
2980 consiting only of a space and a full stop.
2984 The value of this field is usually extracted from the
2985 <file>debian/changelog</file> file - see
2986 <ref id="dpkgchangelog">).
2990 Each version's change information should be preceded by a
2991 "title" line giving at least the version, distribution(s)
2992 and urgency, in a human-readable way.
2996 If data from several versions is being returned the entry
2997 for the most recent version should be returned first, and
2998 entries should be separated by the representation of a
2999 blank line (the "title" line may also be followed by the
3000 representation of blank line).
3004 <sect1 id="f-Binary">
3005 <heading><tt>Binary</tt></heading>
3008 This field is a list of binary packages.
3012 When it appears in the <file>.dsc</file> file it is the list
3013 of binary packages which a source package can produce. It
3014 does not necessarily produce all of these binary packages
3015 for every architecture. The source control file doesn't
3016 contain details of which architectures are appropriate for
3017 which of the binary packages.
3021 When it appears in a <file>.changes</file> file it lists the
3022 names of the binary packages actually being uploaded.
3026 The syntax is a list of binary packages separated by
3028 A space after each comma is conventional.
3029 </footnote>. Currently the packages must be separated using
3030 only spaces in the <file>.changes</file> file.
3034 <sect1 id="f-Installed-Size">
3035 <heading><tt>Installed-Size</tt></heading>
3038 This field appears in the control files of binary
3039 packages, and in the <file>Packages</file> files. It gives
3040 the total amount of disk space required to install the
3045 The disk space is represented in kilobytes as a simple
3050 <sect1 id="f-Files">
3051 <heading><tt>Files</tt></heading>
3054 This field contains a list of files with information about
3055 each one. The exact information and syntax varies with
3056 the context. In all cases the part of the field
3057 contents on the same line as the field name is empty. The
3058 remainder of the field is one line per file, each line
3059 being indented by one space and containing a number of
3060 sub-fields separated by spaces.
3064 In the <file>.dsc</file> file, each line contains the MD5
3065 checksum, size and filename of the tar file and (if applicable)
3066 diff file which make up the remainder of the source
3068 That is, the parts which are not the <tt>.dsc</tt>.
3070 The exact forms of the filenames are described
3071 in <ref id="pkg-sourcearchives">.
3075 In the <file>.changes</file> file this contains one line per
3076 file being uploaded. Each line contains the MD5 checksum,
3077 size, section and priority and the filename.
3078 The <qref id="f-Section">section</qref>
3079 and <qref id="f-Priority">priority</qref>
3080 are the values of the corresponding fields in
3081 the main source control file. If no section or priority is
3082 specified then <tt>-</tt> should be used, though section
3083 and priority values must be specified for new packages to
3084 be installed properly.
3088 The special value <tt>byhand</tt> for the section in a
3089 <tt>.changes</tt> file indicates that the file in question
3090 is not an ordinary package file and must by installed by
3091 hand by the distribution maintainers. If the section is
3092 <tt>byhand</tt> the priority should be <tt>-</tt>.
3096 If a new Debian revision of a package is being shipped and
3097 no new original source archive is being distributed the
3098 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3099 entry for the original source archive
3100 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
3101 but the <file>.changes</file> file should leave it out. In
3102 this case the original source archive on the distribution
3103 site must match exactly, byte-for-byte, the original
3104 source archive which was used to generate the
3105 <file>.dsc</file> file and diff which are being uploaded.</p>
3108 <sect1 id="f-Closes">
3109 <heading><tt>Closes</tt></heading>
3112 A space-separated list of bug report numbers that the upload
3113 governed by the .changes file closes.
3120 <heading>User-defined fields</heading>
3123 Additional user-defined fields may be added to the
3124 source package control file. Such fields will be
3125 ignored, and not copied to (for example) binary or
3126 source package control files or upload control files.
3130 If you wish to add additional unsupported fields to
3131 these output files you should use the mechanism
3136 Fields in the main source control information file with
3137 names starting <tt>X</tt>, followed by one or more of
3138 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3139 be copied to the output files. Only the part of the
3140 field name after the hyphen will be used in the output
3141 file. Where the letter <tt>B</tt> is used the field
3142 will appear in binary package control files, where the
3143 letter <tt>S</tt> is used in source package control
3144 files and where <tt>C</tt> is used in upload control
3145 (<tt>.changes</tt>) files.
3149 For example, if the main source information control file
3152 XBS-Comment: I stand between the candle and the star.
3154 then the binary and source package control files will contain the
3157 Comment: I stand between the candle and the star.
3166 <chapt id="maintainerscripts">
3167 <heading>Package maintainer scripts and installation procedure</heading>
3170 <heading>Introduction to package maintainer scripts</heading>
3173 It is possible to supply scripts as part of a package which
3174 the package management system will run for you when your
3175 package is installed, upgraded or removed.
3179 These scripts are the files <prgn>preinst</prgn>,
3180 <prgn>postinst</prgn>, <prgn>prerm</prgn> and <prgn>postrm</prgn> in the
3181 control area of the package. They must be proper executable
3182 files; if they are scripts (which is recommended), they must
3183 start with the usual <tt>#!</tt> convention. They should be
3184 readable and executable by anyone, and not world-writable.
3188 The package management system looks at the exit status from
3189 these scripts. It is important that they exit with a
3190 non-zero status if there is an error, so that the package
3191 management system can stop its processing. For shell
3192 scripts this means that you <em>almost always</em> need to
3193 use <tt>set -e</tt> (this is usually true when writing shell
3194 scripts, in fact). It is also important, of course, that
3195 they don't exit with a non-zero status if everything went
3200 When a package is upgraded a combination of the scripts from
3201 the old and new packages is called during the upgrade
3202 procedure. If your scripts are going to be at all
3203 complicated you need to be aware of this, and may need to
3204 check the arguments to your scripts.
3208 Broadly speaking the <prgn>preinst</prgn> is called before
3209 (a particular version of) a package is installed, and the
3210 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3211 before (a version of) a package is removed and the
3212 <prgn>postrm</prgn> afterwards.
3216 Programs called from maintainer scripts should not normally
3217 have a path prepended to them. Before installation is
3218 started, the package management system checks to see if the
3219 programs <prgn>ldconfig</prgn>,
3220 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3221 and <prgn>update-rc.d</prgn> can be found via the
3222 <tt>PATH</tt> environment variable. Those programs, and any
3223 other program that one would expect to be on the
3224 <tt>PATH</tt>, should thus be invoked without an absolute
3225 pathname. Maintainer scripts should also not reset the
3226 <tt>PATH</tt>, though they might choose to modify it by
3227 prepending or appending package-specific directories. These
3228 considerations really apply to all shell scripts.</p>
3231 <sect id="idempotency">
3232 <heading>Maintainer scripts Idempotency</heading>
3235 It is necessary for the error recovery procedures that the
3236 scripts be idempotent. This means that if it is run
3237 successfully, and then it is called again, it doesn't bomb
3238 out or cause any harm, but just ensures that everything is
3239 the way it ought to be. If the first call failed, or
3240 aborted half way through for some reason, the second call
3241 should merely do the things that were left undone the first
3242 time, if any, and exit with a success status if everything
3244 This is so that if an error occurs, the user interrupts
3245 <prgn>dpkg</prgn> or some other unforeseen circumstance
3246 happens you don't leave the user with a badly-broken
3247 package when <prgn>dpkg</prgn> attempts to repeat the
3253 <sect id="controllingterminal">
3254 <heading>Controlling terminal for maintainer scripts</heading>
3257 The maintainer scripts are guaranteed to run with a
3258 controlling terminal and can interact with the user.
3259 If they need to prompt for passwords, do full-screen
3260 interaction or something similar you should do these
3261 things to and from <file>/dev/tty</file>, since
3262 <prgn>dpkg</prgn> will at some point redirect scripts'
3263 standard input and output so that it can log the
3264 installation process. Likewise, because these scripts
3265 may be executed with standard output redirected into a
3266 pipe for logging purposes, Perl scripts should set
3267 unbuffered output by setting <tt>$|=1</tt> so that the
3268 output is printed immediately rather than being
3273 Each script should return a zero exit status for
3274 success, or a nonzero one for failure.
3278 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3283 <list compact="compact">
3285 <var>new-preinst</var> <tt>install</tt>
3288 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3291 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3294 <var>old-preinst</var> <tt>abort-upgrade</tt>
3295 <var>new-version</var>
3300 <list compact="compact">
3302 <var>postinst</var> <tt>configure</tt>
3303 <var>most-recently-configured-version</var>
3306 <var>old-postinst</var> <tt>abort-upgrade</tt>
3307 <var>new-version</var>
3310 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3311 <tt>in-favour</tt> <var>package</var>
3312 <var>new-version</var>
3315 <var>deconfigured's-postinst</var>
3316 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3317 <var>failed-install-package</var> <var>version</var>
3318 <tt>removing</tt> <var>conflicting-package</var>
3324 <list compact="compact">
3326 <var>prerm</var> <tt>remove</tt>
3329 <var>old-prerm</var> <tt>upgrade</tt>
3330 <var>new-version</var>
3333 <var>new-prerm</var> <tt>failed-upgrade</tt>
3334 <var>old-version</var>
3337 <var>conflictor's-prerm</var> <tt>remove</tt>
3338 <tt>in-favour</tt> <var>package</var>
3339 <var>new-version</var>
3342 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3343 <tt>in-favour</tt> <var>package-being-installed</var>
3344 <var>version</var> <tt>removing</tt>
3345 <var>conflicting-package</var>
3351 <list compact="compact">
3353 <var>postrm</var> <tt>remove</tt>
3356 <var>postrm</var> <tt>purge</tt>
3359 <var>old-postrm</var> <tt>upgrade</tt>
3360 <var>new-version</var>
3363 <var>new-postrm</var> <tt>failed-upgrade</tt>
3364 <var>old-version</var>
3367 <var>new-postrm</var> <tt>abort-install</tt>
3370 <var>new-postrm</var> <tt>abort-install</tt>
3371 <var>old-version</var>
3374 <var>new-postrm</var> <tt>abort-upgrade</tt>
3375 <var>old-version</var>
3378 <var>disappearer's-postrm</var> <tt>disappear</tt>
3379 <var>overwriter</var>
3380 <var>overwriter-version</var>
3386 <sect id="unpackphase">
3387 <heading>Details of unpack phase of installation or upgrade</heading>
3390 The procedure on installation/upgrade/overwrite/disappear
3391 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3392 stage of <tt>dpkg --install</tt>) is as follows. In each
3393 case, if a major error occurs (unless listed below) the
3394 actions are, in general, run backwards - this means that the
3395 maintainer scripts are run with different arguments in
3396 reverse order. These are the "error unwind" calls listed
3403 If a version of the package is already installed, call
3404 <example compact="compact">
3405 <var>old-prerm</var> upgrade <var>new-version</var>
3409 If the script runs but exits with a non-zero
3410 exit status, <prgn>dpkg</prgn> will attempt:
3411 <example compact="compact">
3412 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3414 Error unwind, for both the above cases:
3415 <example compact="compact">
3416 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3423 If a "conflicting" package is being removed at the same time:
3426 If any packages depended on that conflicting
3427 package and <tt>--auto-deconfigure</tt> is
3428 specified, call, for each such package:
3429 <example compact="compact">
3430 <var>deconfigured's-prerm</var> deconfigure \
3431 in-favour <var>package-being-installed</var> <var>version</var> \
3432 removing <var>conflicting-package</var> <var>version</var>
3435 <example compact="compact">
3436 <var>deconfigured's-postinst</var> abort-deconfigure \
3437 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3438 removing <var>conflicting-package</var> <var>version</var>
3440 The deconfigured packages are marked as
3441 requiring configuration, so that if
3442 <tt>--install</tt> is used they will be
3443 configured again if possible.
3446 To prepare for removal of the conflicting package, call:
3447 <example compact="compact">
3448 <var>conflictor's-prerm</var> remove \
3449 in-favour <var>package</var> <var>new-version</var>
3452 <example compact="compact">
3453 <var>conflictor's-postinst</var> abort-remove \
3454 in-favour <var>package</var> <var>new-version</var>
3463 If the package is being upgraded, call:
3464 <example compact="compact">
3465 <var>new-preinst</var> upgrade <var>old-version</var>
3469 Otherwise, if the package had some configuration
3470 files from a previous version installed (i.e., it
3471 is in the "configuration files only" state):
3472 <example compact="compact">
3473 <var>new-preinst</var> install <var>old-version</var>
3477 Otherwise (i.e., the package was completely purged):
3478 <example compact="compact">
3479 <var>new-preinst</var> install
3481 Error unwind actions, respectively:
3482 <example compact="compact">
3483 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3484 <var>new-postrm</var> abort-install <var>old-version</var>
3485 <var>new-postrm</var> abort-install
3493 The new package's files are unpacked, overwriting any
3494 that may be on the system already, for example any
3495 from the old version of the same package or from
3496 another package. Backups of the old files are kept
3497 temporarily, and if anything goes wrong the package
3498 management system will attempt to put them back as
3499 part of the error unwind.
3503 It is an error for a package to contain files which
3504 are on the system in another package, unless
3505 <tt>Replaces</tt> is used (see <ref id="replaces">).
3507 The following paragraph is not currently the case:
3508 Currently the <tt>- - force-overwrite</tt> flag is
3509 enabled, downgrading it to a warning, but this may not
3515 It is a more serious error for a package to contain a
3516 plain file or other kind of non-directory where another
3517 package has a directory (again, unless
3518 <tt>Replaces</tt> is used). This error can be
3519 overridden if desired using
3520 <tt>--force-overwrite-dir</tt>, but this is not
3525 Packages which overwrite each other's files produce
3526 behavior which, though deterministic, is hard for the
3527 system administrator to understand. It can easily
3528 lead to "missing" programs if, for example, a package
3529 is installed which overwrites a file from another
3530 package, and is then removed again.<footnote>
3531 Part of the problem is due to what is arguably a
3532 bug in <prgn>dpkg</prgn>.
3537 A directory will never be replaced by a symbolic link
3538 to a directory or vice versa; instead, the existing
3539 state (symlink or not) will be left alone and
3540 <prgn>dpkg</prgn> will follow the symlink if there is
3549 If the package is being upgraded, call
3550 <example compact="compact">
3551 <var>old-postrm</var> upgrade <var>new-version</var>
3555 If this fails, <prgn>dpkg</prgn> will attempt:
3556 <example compact="compact">
3557 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3559 Error unwind, for both cases:
3560 <example compact="compact">
3561 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3568 This is the point of no return - if
3569 <prgn>dpkg</prgn> gets this far, it won't back off
3570 past this point if an error occurs. This will
3571 leave the package in a fairly bad state, which
3572 will require a successful re-installation to clear
3573 up, but it's when <prgn>dpkg</prgn> starts doing
3574 things that are irreversible.
3579 Any files which were in the old version of the package
3580 but not in the new are removed.
3584 The new file list replaces the old.
3588 The new maintainer scripts replace the old.
3592 Any packages all of whose files have been overwritten
3593 during the installation, and which aren't required for
3594 dependencies, are considered to have been removed.
3595 For each such package
3598 <prgn>dpkg</prgn> calls:
3599 <example compact="compact">
3600 <var>disappearer's-postrm</var> disappear \
3601 <var>overwriter</var> <var>overwriter-version</var>
3605 The package's maintainer scripts are removed.
3608 It is noted in the status database as being in a
3609 sane state, namely not installed (any conffiles
3610 it may have are ignored, rather than being
3611 removed by <prgn>dpkg</prgn>). Note that
3612 disappearing packages do not have their prerm
3613 called, because <prgn>dpkg</prgn> doesn't know
3614 in advance that the package is going to
3621 Any files in the package we're unpacking that are also
3622 listed in the file lists of other packages are removed
3623 from those lists. (This will lobotomize the file list
3624 of the "conflicting" package if there is one.)
3628 The backup files made during installation, above, are
3634 The new package's status is now sane, and recorded as
3639 Here is another point of no return - if the
3640 conflicting package's removal fails we do not unwind
3641 the rest of the installation; the conflicting package
3642 is left in a half-removed limbo.
3647 If there was a conflicting package we go and do the
3648 removal actions (described below), starting with the
3649 removal of the conflicting package's files (any that
3650 are also in the package being installed have already
3651 been removed from the conflicting package's file list,
3652 and so do not get removed now).
3658 <sect id="configdetails"><heading>Details of configuration</heading>
3661 When we configure a package (this happens with <tt>dpkg
3662 --install</tt> and <tt>dpkg --configure</tt>), we first
3663 update any <tt>conffile</tt>s and then call:
3664 <example compact="compact">
3665 <var>postinst</var> configure <var>most-recently-configured-version</var>
3670 No attempt is made to unwind after errors during
3675 If there is no most recently configured version
3676 <prgn>dpkg</prgn> will pass a null argument; older versions
3677 of dpkg may pass <tt><unknown></tt> (including the
3678 angle brackets) in this case. Even older ones do not pass a
3679 second argument at all, under any circumstances.
3683 <sect id="removedetails"><heading>Details of removal and/or
3684 configuration purging</heading>
3689 <example compact="compact">
3690 <var>prerm</var> remove
3694 The package's files are removed (except <tt>conffile</tt>s).
3697 <example compact="compact">
3698 <var>postrm</var> remove
3703 All the maintainer scripts except the <prgn>postrm</prgn>
3708 If we aren't purging the package we stop here. Note
3709 that packages which have no <prgn>postrm</prgn> and no
3710 <tt>conffile</tt>s are automatically purged when
3711 removed, as there is no difference except for the
3712 <prgn>dpkg</prgn> status.
3716 The <tt>conffile</tt>s and any backup files
3717 (<tt>~</tt>-files, <tt>#*#</tt> files,
3718 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
3722 <example compact="compact">
3723 <var>postrm</var> purge
3727 The package's file list is removed.
3731 No attempt is made to unwind after errors during
3738 <chapt id="relationships">
3739 <heading>Declaring relationships between packages</heading>
3741 <sect id="depsyntax">
3742 <heading>Syntax of relationship fields</heading>
3745 These fields all have a uniform syntax. They are a list of
3746 package names separated by commas.
3750 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3751 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3752 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3753 control file fields of the package, which declare
3754 dependencies on other packages, the package names listed may
3755 also include lists of alternative package names, separated
3756 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
3757 if any one of the alternative packages is installed, that
3758 part of the dependency is considered to be satisfied.
3762 All of the fields except for <tt>Provides</tt> may restrict
3763 their applicability to particular versions of each named
3764 package. This is done in parentheses after each individual
3765 package name; the parentheses should contain a relation from
3766 the list below followed by a version number, in the format
3767 described in <ref id="f-Version">.
3771 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3772 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3773 strictly earlier, earlier or equal, exactly equal, later or
3774 equal and strictly later, respectively. The deprecated
3775 forms <tt><</tt> and <tt>></tt> were used to mean
3776 earlier/later or equal, rather than strictly earlier/later,
3777 so they should not appear in new packages (though
3778 <prgn>dpkg</prgn> still supports them).
3782 Whitespace may appear at any point in the version
3783 specification subject to the rules in <ref
3784 id="controlsyntax">, and must appear where it's necessary to
3785 disambiguate; it is not otherwise significant. For
3786 consistency and in case of future changes to
3787 <prgn>dpkg</prgn> it is recommended that a single space be
3788 used after a version relationship and before a version
3789 number; it is also conventional to put a single space after
3790 each comma, on either side of each vertical bar, and before
3791 each open parenthesis.
3795 For example, a list of dependencies might appear as:
3796 <example compact="compact">
3799 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
3804 All fields that specify build-time relationships
3805 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3806 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3807 may be restricted to a certain set of architectures. This
3808 is indicated in brackets after each individual package name and
3809 the optional version specification. The brackets enclose a
3810 list of Debian architecture names separated by whitespace.
3811 Exclamation marks may be prepended to each of the names.
3812 (It is not permitted for some names to be prepended with
3813 exclamation marks and others not.) If the current Debian
3814 host architecture is not in this list and there are no
3815 exclamation marks in the list, or it is in the list with a
3816 prepended exclamation mark, the package name and the
3817 associated version specification are ignored completely for
3818 the purposes of defining the relationships.
3823 <example compact="compact">
3825 Build-Depends-Indep: texinfo
3826 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3827 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3832 Note that the binary package relationship fields such as
3833 <tt>Depends</tt> appear in one of the binary package
3834 sections of the control file, whereas the build-time
3835 relationships such as <tt>Build-Depends</tt> appear in the
3836 source package section of the control file (which is the
3841 <sect id="binarydeps">
3842 <heading>Binary Dependencies - <tt>Depends</tt>,
3843 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3844 <tt>Pre-Depends</tt>
3848 Packages can declare in their control file that they have
3849 certain relationships to other packages - for example, that
3850 they may not be installed at the same time as certain other
3851 packages, and/or that they depend on the presence of others.
3855 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
3856 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt> and
3857 <tt>Conflicts</tt> control file fields.
3861 These six fields are used to declare a dependency
3862 relationship by one package on another. Except for
3863 <tt>Enhances</tt>, they appear in the depending (binary)
3864 package's control file. (<tt>Enhances</tt> appears in the
3865 recommending package's control file.)
3869 A <tt>Depends</tt> field takes effect <em>only</em> when a
3870 package is to be configured. It does not prevent a package
3871 being on the system in an unconfigured state while its
3872 dependencies are unsatisfied, and it is possible to replace
3873 a package whose dependencies are satisfied and which is
3874 properly installed with a different version whose
3875 dependencies are not and cannot be satisfied; when this is
3876 done the depending package will be left unconfigured (since
3877 attempts to configure it will give errors) and will not
3878 function properly. If it is necessary, a
3879 <tt>Pre-Depends</tt> field can be used, which has a partial
3880 effect even when a package is being unpacked, as explained
3881 in detail below. (The other three dependency fields,
3882 <tt>Recommends</tt>, <tt>Suggests</tt> and
3883 <tt>Enhances</tt>, are only used by the various front-ends
3884 to <prgn>dpkg</prgn> such as <prgn>dselect</prgn>.)
3888 For this reason packages in an installation run are usually
3889 all unpacked first and all configured later; this gives
3890 later versions of packages with dependencies on later
3891 versions of other packages the opportunity to have their
3892 dependencies satisfied.
3896 The <tt>Depends</tt> field thus allows package maintainers
3897 to impose an order in which packages should be configured.
3901 The meaning of the five dependency fields is as follows:
3903 <tag><tt>Depends</tt></tag>
3906 This declares an absolute dependency. A package will
3907 not be configured unless all of the packages listed in
3908 its <tt>Depends</tt> field have been correctly
3913 The <tt>Depends</tt> field should be used if the
3914 depended-on package is required for the depending
3915 package to provide a significant amount of
3920 The <tt>Depends</tt> field should also be used if the
3921 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
3922 <prgn>postrm</prgn> scripts require the package to be
3923 present in order to run. Note, however, that the
3924 <prgn>postrm</prgn> cannot rely on any non-essential
3925 packages to be present during the <tt>purge</tt>
3929 <tag><tt>Recommends</tt></tag>
3932 This declares a strong, but not absolute, dependency.
3936 The <tt>Recommends</tt> field should list packages
3937 that would be found together with this one in all but
3938 unusual installations.
3942 <tag><tt>Suggests</tt></tag>
3944 This is used to declare that one package may be more
3945 useful with one or more others. Using this field
3946 tells the packaging system and the user that the
3947 listed packages are related to this one and can
3948 perhaps enhance its usefulness, but that installing
3949 this one without them is perfectly reasonable.
3952 <tag><tt>Enhances</tt></tag>
3954 This field is similar to Suggests but works in the
3955 opposite direction. It is used to declare that a
3956 package can enhance the functionality of another
3960 <tag><tt>Pre-Depends</tt></tag>
3963 This field is like <tt>Depends</tt>, except that it
3964 also forces <prgn>dpkg</prgn> to complete installation
3965 of the packages named before even starting the
3966 installation of the package which declares the
3967 pre-dependency, as follows:
3971 When a package declaring a pre-dependency is about to
3972 be <em>unpacked</em> the pre-dependency can be
3973 satisfied if the depended-on package is either fully
3974 configured, <em>or even if</em> the depended-on
3975 package(s) are only unpacked or half-configured,
3976 provided that they have been configured correctly at
3977 some point in the past (and not removed or partially
3978 removed since). In this case, both the
3979 previously-configured and currently unpacked or
3980 half-configured versions must satisfy any version
3981 clause in the <tt>Pre-Depends</tt> field.
3985 When the package declaring a pre-dependency is about
3986 to be <em>configured</em>, the pre-dependency will be
3987 treated as a normal <tt>Depends</tt>, that is, it will
3988 be considered satisfied only if the depended-on
3989 package has been correctly configured.
3993 <tt>Pre-Depends</tt> should be used sparingly,
3994 preferably only by packages whose premature upgrade or
3995 installation would hamper the ability of the system to
3996 continue with any upgrade that might be in progress.
4000 <tt>Pre-Depends</tt> are also required if the
4001 <prgn>preinst</prgn> script depends on the named
4002 package. It is best to avoid this situation if
4010 When selecting which level of dependency to use you should
4011 consider how important the depended-on package is to the
4012 functionality of the one declaring the dependency. Some
4013 packages are composed of components of varying degrees of
4014 importance. Such a package should list using
4015 <tt>Depends</tt> the package(s) which are required by the
4016 more important components. The other components'
4017 requirements may be mentioned as Suggestions or
4018 Recommendations, as appropriate to the components' relative
4023 <sect id="conflicts">
4024 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4027 When one binary package declares a conflict with another
4028 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4029 refuse to allow them to be installed on the system at the
4034 If one package is to be installed, the other must be removed
4035 first - if the package being installed is marked as
4036 replacing (see <ref id="replaces">) the one on the system,
4037 or the one on the system is marked as deselected, or both
4038 packages are marked <tt>Essential</tt>, then
4039 <prgn>dpkg</prgn> will automatically remove the package
4040 which is causing the conflict, otherwise it will halt the
4041 installation of the new package with an error. This
4042 mechanism is specifically designed to produce an error when
4043 the installed package is <tt>Essential</tt>, but the new
4048 A package will not cause a conflict merely because its
4049 configuration files are still installed; it must be at least
4054 A special exception is made for packages which declare a
4055 conflict with their own package name, or with a virtual
4056 package which they provide (see below): this does not
4057 prevent their installation, and allows a package to conflict
4058 with others providing a replacement for it. You use this
4059 feature when you want the package in question to be the only
4060 package providing some feature.
4064 A <tt>Conflicts</tt> entry should almost never have an
4065 "earlier than" version clause. This would prevent
4066 <prgn>dpkg</prgn> from upgrading or installing the package
4067 which declared such a conflict until the upgrade or removal
4068 of the conflicted-with package had been completed.
4072 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4076 As well as the names of actual ("concrete") packages, the
4077 package relationship fields <tt>Depends</tt>,
4078 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4079 <tt>Pre-Depends</tt>, <tt>Conflicts</tt>,
4080 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4081 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4082 may mention "virtual packages".
4086 A <em>virtual package</em> is one which appears in the
4087 <tt>Provides</tt> control file field of another package.
4088 The effect is as if the package(s) which provide a
4089 particular virtual package name had been listed by name
4090 everywhere the virtual package name appears. (See also <ref
4095 If there are both concrete and virtual packages of the same
4096 name, then the dependency may be satisfied (or the conflict
4097 caused) by either the concrete package with the name in
4098 question or any other concrete package which provides the
4099 virtual package with the name in question. This is so that,
4100 for example, supposing we have
4101 <example compact="compact">
4105 and someone else releases an enhanced version of the
4106 <tt>bar</tt> package (for example, a non-US variant), they
4108 <example compact="compact">
4112 and the <tt>bar-plus</tt> package will now also satisfy the
4113 dependency for the <tt>foo</tt> package.
4117 If a dependency or a conflict has a version number attached
4118 then only real packages will be considered to see whether
4119 the relationship is satisfied (or the prohibition violated,
4120 for a conflict) - it is assumed that a real package which
4121 provides the virtual package is not of the "right" version.
4122 So, a <tt>Provides</tt> field may not contain version
4123 numbers, and the version number of the concrete package
4124 which provides a particular virtual package will not be
4125 looked at when considering a dependency on or conflict with
4126 the virtual package name.
4130 It is likely that the ability will be added in a future
4131 release of <prgn>dpkg</prgn> to specify a version number for
4132 each virtual package it provides. This feature is not yet
4133 present, however, and is expected to be used only
4138 If you want to specify which of a set of real packages
4139 should be the default to satisfy a particular dependency on
4140 a virtual package, you should list the real package as an
4141 alternative before the virtual one.
4146 <sect id="replaces"><heading>Overwriting files and replacing
4147 packages - <tt>Replaces</tt></heading>
4150 Packages can declare in their control file that they should
4151 overwrite files in certain other packages, or completely
4152 replace other packages. The <tt>Replaces</tt> control file
4153 field has these two distinct purposes.
4156 <sect1><heading>Overwriting files in other packages</heading>
4159 Firstly, as mentioned before, it is usually an error for a
4160 package to contain files which are on the system in
4165 However, if the overwriting package declares that it
4166 <tt>Replaces</tt> the one containing the file being
4167 overwritten, then <prgn>dpkg</prgn> will replace the file
4168 from the old package with that from the new. The file
4169 will no longer be listed as "owned" by the old package.
4173 If a package is completely replaced in this way, so that
4174 <prgn>dpkg</prgn> does not know of any files it still
4175 contains, it is considered to have "disappeared". It will
4176 be marked as not wanted on the system (selected for
4177 removal) and not installed. Any <tt>conffile</tt>s
4178 details noted for the package will be ignored, as they
4179 will have been taken over by the overwriting package. The
4180 package's <prgn>postrm</prgn> script will be run with a
4181 special argument to allow the package to do any final
4182 cleanup required. See <ref id="mscriptsinstact">.
4185 Replaces is a one way relationship -- you have to
4186 install the replacing package after the replaced
4193 For this usage of <tt>Replaces</tt>, virtual packages (see
4194 <ref id="virtual">) are not considered when looking at a
4195 <tt>Replaces</tt> field - the packages declared as being
4196 replaced must be mentioned by their real names.
4200 Furthermore, this usage of <tt>Replaces</tt> only takes
4201 effect when both packages are at least partially on the
4202 system at once, so that it can only happen if they do not
4203 conflict or if the conflict has been overridden.
4208 <sect1><heading>Replacing whole packages, forcing their
4212 Secondly, <tt>Replaces</tt> allows the packaging system to
4213 resolve which package should be removed when there is a
4214 conflict - see <ref id="conflicts">. This usage only
4215 takes effect when the two packages <em>do</em> conflict,
4216 so that the two usages of this field do not interfere with
4221 In this situation, the package declared as being replaced
4222 can be a virtual package, so for example, all mail
4223 transport agents (MTAs) would have the following fields in
4224 their control files:
4225 <example compact="compact">
4226 Provides: mail-transport-agent
4227 Conflicts: mail-transport-agent
4228 Replaces: mail-transport-agent
4230 ensuring that only one MTA can be installed at any one
4235 <sect id="sourcebinarydeps">
4236 <heading>Relationships between source and binary packages -
4237 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4238 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4242 Source packages that require certain binary packages to be
4243 installed or absent at the time of building the package
4244 can declare relationships to those binary packages.
4248 This is done using the <tt>Build-Depends</tt>,
4249 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4250 <tt>Build-Conflicts-Indep</tt> control file fields.
4254 Build-dependencies on "build-essential" binary packages can be
4255 omitted. Please see <ref id="pkg-relations"> for more information.
4259 The dependencies and conflicts they define must be satisfied
4260 (as defined earlier for binary packages) in order to invoke
4261 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4263 If you make "build-arch" or "binary-arch", you need
4264 Build-Depends. If you make "build-indep" or
4265 "binary-indep", you need Build-Depends and
4266 Build-Depends-Indep. If you make "build" or "binary",
4270 There is no Build-Depends-Arch; the autobuilders will
4271 only need the Build-Depends if they know how to build
4272 only build-arch and binary-arch. Anyone building the
4273 build-indep/binary-indep targets is basically assumed to
4274 be building the whole package and so installs all build
4278 The purpose of the original split, I recall, was so that
4279 the autobuilders wouldn't need to install extra packages
4280 needed only for the binary-indep targets. But without a
4281 build-arch/build-indep split, this didn't work, since
4282 most of the work is done in the build target, not in the
4288 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4290 The <tt>Build-Depends</tt> and
4291 <tt>Build-Conflicts</tt> fields must be satisfied when
4292 any of the following targets is invoked:
4293 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4294 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4295 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4297 <tag><tt>Build-Depends-Indep</tt>,
4298 <tt>Build-Conflicts-Indep</tt></tag>
4300 The <tt>Build-Depends-Indep</tt> and
4301 <tt>Build-Conflicts-Indep</tt> fields must be
4302 satisfied when any of the following targets is
4303 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4304 <tt>binary</tt> and <tt>binary-indep</tt>.
4314 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4317 Packages containing shared libraries must be constructed with
4318 a little care to make sure that the shared library is always
4319 available. This is especially important for packages whose
4320 shared libraries are vitally important, such as the C library
4321 (currently <tt>libc6</tt>).
4325 Packages involving shared libraries should be split up into
4326 several binary packages. This section mostly deals with how
4327 this separation is to be accomplished; rules for files within
4328 the shared library packages are in <ref id="libraries"> instead.
4331 <sect id="sharedlibs-runtime">
4332 <heading>Run-time shared libraries</heading>
4335 The run-time shared library needs to be placed in a package called
4336 <package><var>libraryname</var><var>soversion</var></package>, where
4337 <file><var>soversion</var></file> is the version number in the
4338 soname of the shared library<footnote>
4339 The soname is the shared object name: it's the thing
4340 that has to match exactly between building an executable
4341 and running it for the dynamic linker to be able run the
4342 program. For example, if the soname of the library is
4343 <file>libfoo.so.6</file>, the library package would be
4344 called <file>libfoo6</file>.
4346 Alternatively, if it would be confusing to directly append
4347 <var>soversion</var> to <var>libraryname</var> (e.g. because
4348 <var>libraryname</var> itself ends in a number), you may use
4349 <package><var>libraryname</var>-<var>soversion</var></package> and
4350 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4355 If you have several shared libraries built from the same
4356 source tree you may lump them all together into a single
4357 shared library package, provided that you change all of
4358 their sonames at once (so that you don't get filename
4359 clashes if you try to install different versions of the
4360 combined shared libraries package).
4364 The package should install the shared libraries under
4365 their normal names. For example, the <package>libgdbm3</package>
4366 package should install <file>libgdbm.so.3.0.0</file> as
4367 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4368 renamed or re-linked by any <prgn>prerm</prgn> or
4369 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4370 of renaming things safely without affecting running programs,
4371 and attempts to interfere with this are likely to lead to
4376 Shared libraries should not be installed executable, since
4377 the dynamic linker does not require this and trying to
4378 execute a shared library usually results in a core dump.
4382 The run-time library package should include the symbolic link that
4383 <prgn>ldconfig</prgn> would create for the shared libraries.
4384 For example, the <package>libgdbm3</package> package should include
4385 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4386 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4387 linker (for example <prgn>ld.so</prgn> or
4388 <prgn>ld-linux.so.*</prgn>) can find the library between the
4389 time that <prgn>dpkg</prgn> installs it and the time that
4390 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4392 The package management system requires the library to be
4393 placed before the symbolic link pointing to it in the
4394 <file>.deb</file> file. This is so that when
4395 <prgn>dpkg</prgn> comes to install the symlink
4396 (overwriting the previous symlink pointing at an older
4397 version of the library), the new shared library is already
4398 in place. In the past, this was achieved by creating the
4399 library in the temporary packaging directory before
4400 creating the symlink. Unfortunately, this was not always
4401 effective, since the building of the tar file in the
4402 <file>.deb</file> depended on the behavior of the underlying
4403 file system. Some file systems (such as reiserfs) reorder
4404 the files so that the order of creation is forgotten.
4405 Since version 1.7.0, <prgn>dpkg</prgn>
4406 reorders the files itself as necessary when building a
4407 package. Thus it is no longer important to concern
4408 oneself with the order of file creation.
4412 <sect1 id="ldconfig">
4413 <heading><tt>ldconfig</tt></heading>
4416 Any package installing shared libraries in one of the default
4417 library directories of the dynamic linker (which are currently
4418 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4419 listed in <file>/etc/ld.so.conf</file><footnote>
4421 <list compact="compact">
4422 <item>/usr/X11R6/lib/Xaw3d</item>
4423 <item>/usr/local/lib</item>
4424 <item>/usr/lib/libc5-compat</item>
4425 <item>/lib/libc5-compat</item>
4426 <item>/usr/X11R6/lib</item>
4429 must use <prgn>ldconfig</prgn> to update the shared library
4434 The package must call <prgn>ldconfig</prgn> in the
4435 <prgn>postinst</prgn> script if the first argument is
4436 <tt>configure</tt>; the <prgn>postinst</prgn> script may
4437 optionally invoke <prgn>ldconfig</prgn> at other times. The
4438 package should call <prgn>ldconfig</prgn> in the
4439 <prgn>postrm</prgn> script if the first argument is
4440 <tt>remove</tt>. The maintainer scripts must not invoke
4441 <prgn>ldconfig</prgn> under any circumstances other than those
4442 described in this paragraph.<footnote>
4444 During install or upgrade, the preinst is called before
4445 the new files are installed, so calling "ldconfig" is
4446 pointless. The preinst of an existing package can also be
4447 called if an upgrade fails. However, this happens during
4448 the critical time when a shared libs may exist on-disk
4449 under a temporary name. Thus, it is dangerous and
4450 forbidden by current policy to call "ldconfig" at this
4455 When a package is installed or upgraded, "postinst
4456 configure" runs after the new files are safely on-disk.
4457 Since it is perfectly safe to invoke ldconfig
4458 unconditionally in a postinst, it is OK for a package to
4459 simply put ldconfig in its postinst without checking the
4460 argument. The postinst can also be called to recover from
4461 a failed upgrade. This happens before any new files are
4462 unpacked, so there is no reason to call "ldconfig" at this
4467 For a package that is being removed, prerm is
4468 called with all the files intact, so calling ldconfig is
4469 useless. The other calls to "prerm" happen in the case of
4470 upgrade at a time when all the files of the old package
4471 are on-disk, so again calling "ldconfig" is pointless.
4475 postrm, on the other hand, is called with the "remove"
4476 argument just after the files are removed, so this is the
4477 proper time to call "ldconfig" to notify the system of the
4478 fact shared libraries from the package are removed.
4479 The postrm can be called at several other times. At the
4480 time of "postrm purge", "postrm abort-install", or "postrm
4481 abort-upgrade", calling "ldconfig" is useless because the
4482 shared lib files are not on-disk. However, when "postrm"
4483 is invoked with arguments "upgrade", "failed-upgrade", or
4484 "disappear", a shared lib may exist on-disk under a
4493 <sect id="sharedlibs-runtime-progs">
4494 <heading>Run-time support programs</heading>
4497 If your package has some run-time support programs which use
4498 the shared library you must not put them in the shared
4499 library package. If you do that then you won't be able to
4500 install several versions of the shared library without
4501 getting filename clashes.
4505 Instead, either create another package for the runtime binaries
4506 (this package might typically be named
4507 <package><var>libraryname</var>-runtime</package>; note the absence
4508 of the <var>soversion</var> in the package name), or if the
4509 development package is small, include them in there.
4513 <sect id="sharedlibs-static">
4514 <heading>Static libraries</heading>
4517 The static library (<file><var>libraryname.a</var></file>)
4518 is usually provided in addition to the shared version.
4519 It is placed into the development package (see below).
4523 In some cases, it is acceptable for a library to be
4524 available in static form only; these cases include:
4526 <item>libraries for languages whose shared library support
4527 is immature or unstable</item>
4528 <item>libraries whose interfaces are in flux or under
4529 development (commonly the case when the library's
4530 major version number is zero, or where the ABI breaks
4531 across patchlevels)</item>
4532 <item>libraries which are explicitly intended to be
4533 available only in static form by their upstream
4538 <sect id="sharedlibs-dev">
4539 <heading>Development files</heading>
4542 The development files associated to a shared library need to be
4543 placed in a package called
4544 <package><var>libraryname</var><var>soversion</var>-dev</package>,
4545 or if you prefer only to support one development version at a
4546 time, <package><var>libraryname</var>-dev</package>.
4550 In case several development versions of a library exist, you may
4551 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
4552 <ref id="conflicts">) to ensure that the user only installs one
4553 development version at a time (as different development versions are
4554 likely to have the same header files in them, which would cause a
4555 filename clash if both were installed).
4559 The development package should contain a symlink for the associated
4560 shared library without a version number. For example, the
4561 <package>libgdbm-dev</package> package should include a symlink
4562 from <file>/usr/lib/libgdbm.so</file> to
4563 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
4564 (<prgn>ld</prgn>) when compiling packages, as it will only look for
4565 <file>libgdbm.so</file> when compiling dynamically.
4569 <sect id="sharedlibs-intradeps">
4570 <heading>Dependencies between the packages of the same library</heading>
4573 Typically the development version should have an exact
4574 version dependency on the runtime library, to make sure that
4575 compilation and linking happens correctly. The
4576 <tt>${Source-Version}</tt> substitution variable can be
4577 useful for this purpose.
4581 <sect id="sharedlibs-shlibdeps">
4582 <heading>Dependencies between the library and other packages -
4583 the <tt>shlibs</tt> system</heading>
4586 If a package contains a binary or library which links to a
4587 shared library, we must ensure that when the package is
4588 installed on the system, all of the libraries needed are
4589 also installed. This requirement led to the creation of the
4590 <tt>shlibs</tt> system, which is very simple in its design:
4591 any package which <em>provides</em> a shared library also
4592 provides information on the package dependencies required to
4593 ensure the presence of this library, and any package which
4594 <em>uses</em> a shared library uses this information to
4595 determine the dependencies it requires. The files which
4596 contain the mapping from shared libraries to the necessary
4597 dependency information are called <file>shlibs</file> files.
4601 Thus, when a package is built which contains any shared
4602 libraries, it must provide a <file>shlibs</file> file for other
4603 packages to use, and when a package is built which contains
4604 any shared libraries or compiled binaries, it must run
4605 <prgn>dpkg-shlibdeps</prgn> on these to determine the
4606 libraries used and hence the dependencies needed by this
4609 In the past, the shared libraries linked to were
4610 determined by calling <prgn>ldd</prgn>, but now
4611 <prgn>objdump</prgn> is used to do this. The only
4612 change this makes to package building is that
4613 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
4614 libraries, whereas in the past this was unnecessary.
4615 The rest of this footnote explains the advantage that
4620 We say that a binary <tt>foo</tt> <em>directly</em> uses
4621 a library <tt>libbar</tt> if it is explicitly linked
4622 with that library (that is, it uses the flag
4623 <tt>-lbar</tt> during the linking stage). Other
4624 libraries that are needed by <tt>libbar</tt> are linked
4625 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
4626 linker will load them automatically when it loads
4627 <tt>libbar</tt>. A package should depend on
4628 the libraries it directly uses, and the dependencies for
4629 those libraries should automatically pull in the other
4634 Unfortunately, the <prgn>ldd</prgn> program shows both
4635 the directly and indirectly used libraries, meaning that
4636 the dependencies determined included both direct and
4637 indirect dependencies. The use of <prgn>objdump</prgn>
4638 avoids this problem by determining only the directly
4643 A good example of where this helps is the following. We
4644 could update <tt>libimlib</tt> with a new version that
4645 supports a new graphics format called dgf (but retaining
4646 the same major version number). If we used the old
4647 <prgn>ldd</prgn> method, every package that uses
4648 <tt>libimlib</tt> would need to be recompiled so it
4649 would also depend on <tt>libdgf</tt> or it wouldn't run
4650 due to missing symbols. However with the new system,
4651 packages using <tt>libimlib</tt> can rely on
4652 <tt>libimlib</tt> itself having the dependency on
4653 <tt>libdgf</tt> and so they would not need rebuilding.
4659 In the following sections, we will first describe where the
4660 various <tt>shlibs</tt> files are to be found, then how to
4661 use <prgn>dpkg-shlibdeps</prgn>, and finally the
4662 <tt>shlibs</tt> file format and how to create them if your
4663 package contains a shared library.
4667 <heading>The <tt>shlibs</tt> files present on the system</heading>
4670 There are several places where <tt>shlibs</tt> files are
4671 found. The following list gives them in the order in which
4672 they are read by <prgn>dpkg-shlibdeps</prgn>. (The first
4673 one which gives the required information is used.)
4679 <p><file>debian/shlibs.local</file></p>
4682 This lists overrides for this package. Its use is
4683 described below (see <ref id="shlibslocal">).
4688 <p><file>/etc/dpkg/shlibs.override</file></p>
4691 This lists global overrides. This list is normally
4692 empty. It is maintained by the local system
4698 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
4701 When packages are being built, any
4702 <file>debian/shlibs</file> files are copied into the
4703 control file area of the temporary build directory and
4704 given the name <file>shlibs</file>. These files give
4705 details of any shared libraries included in the
4707 An example may help here. Let us say that the
4708 source package <tt>foo</tt> generates two binary
4709 packages, <tt>libfoo2</tt> and
4710 <tt>foo-runtime</tt>. When building the binary
4711 packages, the two packages are created in the
4712 directories <file>debian/libfoo2</file> and
4713 <file>debian/foo-runtime</file> respectively.
4714 (<file>debian/tmp</file> could be used instead of one
4715 of these.) Since <tt>libfoo2</tt> provides the
4716 <tt>libfoo</tt> shared library, it will require a
4717 <tt>shlibs</tt> file, which will be installed in
4718 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
4720 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
4721 when <prgn>dpkg-shlibdeps</prgn> is run on the
4723 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
4725 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
4726 determine whether <tt>foo-prog</tt>'s library
4727 dependencies are satisfied by any of the libraries
4728 provided by <tt>libfoo2</tt>. For this reason,
4729 <prgn>dpkg-shlibdeps</prgn> must only be run once
4730 all of the individual binary packages'
4731 <tt>shlibs</tt> files have been installed into the
4738 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
4741 These are the <file>shlibs</file> files corresponding to
4742 all of the packages installed on the system, and are
4743 maintained by the relevant package maintainers.
4748 <p><file>/etc/dpkg/shlibs.default</file></p>
4751 This file lists any shared libraries whose packages
4752 have failed to provide correct <file>shlibs</file> files.
4753 It was used when the <file>shlibs</file> setup was first
4754 introduced, but it is now normally empty. It is
4755 maintained by the <tt>dpkg</tt> maintainer.
4763 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
4764 <file>shlibs</file> files</heading>
4767 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
4768 <file>debian/rules</file> file. If your package contains only
4769 compiled binaries and libraries (but no scripts), you can
4770 use a command such as:
4771 <example compact="compact">
4772 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
4773 debian/tmp/usr/lib/*
4775 Otherwise, you will need to explicitly list the compiled
4776 binaries and libraries.<footnote>
4777 If you are using <tt>debhelper</tt>, the
4778 <prgn>dh_shlibdeps</prgn> program will do this work for
4779 you. It will also correctly handle multi-binary
4785 This command puts the dependency information into the
4786 <file>debian/substvars</file> file, which is then used by
4787 <prgn>dpkg-gencontrol</prgn>. You will need to place a
4788 <tt>${shlib:Depends}</tt> variable in the <tt>Depends</tt>
4789 field in the control file for this to work.
4793 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
4794 done. If it does complain you might need to create your own
4795 <file>debian/shlibs.local</file> file, as explained below (see
4796 <ref id="shlibslocal">).
4800 If you have multiple binary packages, you will need to call
4801 <prgn>dpkg-shlibdeps</prgn> on each one which contains
4802 compiled libraries or binaries. In such a case, you will
4803 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
4804 utilities to specify a different <file>substvars</file> file.
4805 For more details on this and other options, see <manref
4806 name="dpkg-shlibdeps" section="1">.
4811 <heading>The <file>shlibs</file> File Format</heading>
4814 Each <file>shlibs</file> file has the same format. Lines
4815 beginning with <tt>#</tt> are considered to be comments and
4816 are ignored. Each line is of the form:
4817 <example compact="compact">
4818 <var>library-name</var> <var>soname-version-number</var> <var>dependencies ...</var>
4823 We will explain this by reference to the example of the
4824 <tt>zlib1g</tt> package, which (at the time of writing)
4825 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
4829 <var>library-name</var> is the name of the shared library,
4830 in this case <tt>libz</tt>. (This must match the name part
4831 of the soname, see below.)
4835 <var>soname-version-number</var> is the version part of the
4836 soname of the library. The soname is the thing that must
4837 exactly match for the library to be recognized by the
4838 dynamic linker, and is usually of the form
4839 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
4840 example, <tt>libz.so.1</tt>.<footnote>
4841 This can be determined using the command
4842 <example compact="compact">
4843 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
4846 The version part is the part which comes after
4847 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
4851 <var>dependencies</var> has the same syntax as a dependency
4852 field in a binary package control file. It should give
4853 details of which packages are required to satisfy a binary
4854 built against the version of the library contained in the
4855 package. See <ref id="depsyntax"> for details.
4859 In our example, if the first version of the <tt>zlib1g</tt>
4860 package which contained a minor number of at least
4861 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
4862 <tt>shlibs</tt> entry for this library could say:
4863 <example compact="compact">
4864 libz 1 zlib1g (>= 1:1.1.3)
4866 The version-specific dependency is to avoid warnings from
4867 the dynamic linker about using older shared libraries with
4873 <heading>Providing a <file>shlibs</file> file</heading>
4876 If your package provides a shared library, you should create
4877 a <file>shlibs</file> file following the format described above.
4878 It is usual to call this file <file>debian/shlibs</file> (but if
4879 you have multiple binary packages, you might want to call it
4880 <file>debian/shlibs.<var>package</var></file> instead). Then
4881 let <file>debian/rules</file> install it in the control area:
4882 <example compact="compact">
4883 install -m644 debian/shlibs debian/tmp/DEBIAN
4885 or, in the case of a multi-binary package:
4886 <example compact="compact">
4887 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
4889 An alternative way of doing this is to create the
4890 <file>shlibs</file> file in the control area directly from
4891 <file>debian/rules</file> without using a <file>debian/shlibs</file>
4892 file at all,<footnote>
4893 This is what <prgn>dh_makeshlibs</prgn> in the
4894 <tt>debhelper</tt> suite does.
4896 since the <file>debian/shlibs</file> file itself is ignored by
4897 <prgn>dpkg-shlibdeps</prgn>.
4901 As <prgn>dpkg-shlibdeps</prgn> reads the
4902 <file>DEBIAN/shlibs</file> files in all of the binary packages
4903 being built from this source package, all of the
4904 <file>DEBIAN/shlibs</file> files should be installed before
4905 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
4910 <sect1 id="shlibslocal">
4911 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
4914 This file is intended only as a <em>temporary</em> fix if
4915 your binaries or libraries depend on a library whose package
4916 does not yet provide a correct <file>shlibs</file> file.
4920 We will assume that you are trying to package a binary
4921 <tt>foo</tt>. When you try running
4922 <prgn>dpkg-shlibdeps</prgn> you get the following error
4923 message (<tt>-O</tt> displays the dependency information on
4924 <tt>stdout</tt> instead of writing it to
4925 <tt>debian/substvars</tt>, and the lines have been wrapped
4926 for ease of reading):
4927 <example compact="compact">
4928 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
4929 dpkg-shlibdeps: warning: unable to find dependency
4930 information for shared library libbar (soname 1,
4931 path /usr/lib/libbar.so.1, dependency field Depends)
4932 shlibs:Depends=libc6 (>= 2.2.2-2)
4934 You can then run <prgn>ldd</prgn> on the binary to find the
4935 full location of the library concerned:
4936 <example compact="compact">
4938 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
4939 libc.so.6 => /lib/libc.so.6 (0x40032000)
4940 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
4942 So the <prgn>foo</prgn> binary depends on the
4943 <prgn>libbar</prgn> shared library, but no package seems to
4944 provide a <file>*.shlibs</file> file handling
4945 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
4946 determine the package responsible:
4947 <example compact="compact">
4948 $ dpkg -S /usr/lib/libbar.so.1
4949 bar1: /usr/lib/libbar.so.1
4950 $ dpkg -s bar1 | grep Version
4953 This tells us that the <tt>bar1</tt> package, version 1.0-1,
4954 is the one we are using. Now we can file a bug against the
4955 <tt>bar1</tt> package and create our own
4956 <file>debian/shlibs.local</file> to locally fix the problem.
4957 Including the following line into your
4958 <file>debian/shlibs.local</file> file:
4959 <example compact="compact">
4960 libbar 1 bar1 (>= 1.0-1)
4962 should allow the package build to work.
4966 As soon as the maintainer of <tt>bar1</tt> provides a
4967 correct <file>shlibs</file> file, you should remove this line
4968 from your <file>debian/shlibs.local</file> file. (You should
4969 probably also then have a versioned <tt>Build-Depends</tt>
4970 on <tt>bar1</tt> to help ensure that others do not have the
4971 same problem building your package.)
4980 <chapt id="opersys"><heading>The Operating System</heading>
4983 <heading>Filesystem hierarchy</heading>
4987 <heading>Filesystem Structure</heading>
4990 The location of all installed files and directories must
4991 comply with the Filesystem Hierarchy Standard (FHS),
4992 version 2.1, except where doing so would violate other
4993 terms of Debian Policy. The version of this document
4994 referred here can be found in the <tt>debian-policy</tt>
4996 <url id="http://www.debian.org/doc/packaging-manuals/fhs/"
4997 name="FHS (Debian copy)"> alongside this manual (or, if
4998 you have the <package>debian-policy</package> installed,
5000 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5001 (local copy)">). The
5002 latest version, which may be a more recent version, may
5004 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5005 Specific questions about following the standard may be
5006 asked on the <tt>debian-devel</tt> mailing list, or
5007 referred to the FHS mailing list (see the
5008 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5014 <heading>Site-specific programs</heading>
5017 As mandated by the FHS, packages must not place any
5018 files in <file>/usr/local</file>, either by putting them in
5019 the file system archive to be unpacked by <prgn>dpkg</prgn>
5020 or by manipulating them in their maintainer scripts.
5024 However, the package may create empty directories below
5025 <file>/usr/local</file> so that the system administrator knows
5026 where to place site-specific files. These directories
5027 should be removed on package removal if they are
5032 Note, that this applies only to directories <em>below</em>
5033 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
5034 Packages must not create sub-directories in the directory
5035 <file>/usr/local</file> itself, except those listed in FHS,
5036 section 4.5. However, you may create directories below
5037 them as you wish. You must not remove any of the
5038 directories listed in 4.5, even if you created them.
5042 Since <file>/usr/local</file> can be mounted read-only from a
5043 remote server, these directories must be created and
5044 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5045 maintainer scripts and not be included in the
5046 <file>.deb</file> archive. These scripts must not fail if
5047 either of these operations fail.
5051 For example, the <tt>emacsen-common</tt> package could
5052 contain something like
5053 <example compact="compact">
5054 if [ ! -e /usr/local/share/emacs ]
5056 if mkdir /usr/local/share/emacs 2>/dev/null
5058 chown root:staff /usr/local/share/emacs
5059 chmod 2775 /usr/local/share/emacs
5063 in its <prgn>postinst</prgn> script, and
5064 <example compact="compact">
5065 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5066 rmdir /usr/local/share/emacs 2>/dev/null || true
5068 in the <prgn>prerm</prgn> script. (Note that this form is
5069 used to ensure that if the script is interrupted, the
5070 directory <file>/usr/local/share/emacs</file> will still be
5075 If you do create a directory in <file>/usr/local</file> for
5076 local additions to a package, you should ensure that
5077 settings in <file>/usr/local</file> take precedence over the
5078 equivalents in <file>/usr</file>.
5082 However, because <file>/usr/local</file> and its contents are
5083 for exclusive use of the local administrator, a package
5084 must not rely on the presence or absence of files or
5085 directories in <file>/usr/local</file> for normal operation.
5089 The <file>/usr/local</file> directory itself and all the
5090 subdirectories created by the package should (by default) have
5091 permissions 2775 (group-writable and set-group-id) and be
5092 owned by <tt>root.staff</tt>.
5097 <heading>The system-wide mail directory</heading>
5099 The system-wide mail directory is <file>/var/mail</file>. This
5100 directory is part of the base system and should not owned
5101 by any particular mail agents. The use of the old
5102 location <file>/var/spool/mail</file> is deprecated, even
5103 though the spool may still be physically located there.
5104 To maintain partial upgrade compatibility for systems
5105 which have <file>/var/spool/mail</file> as their physical mail
5106 spool, packages using <file>/var/mail</file> must depend on
5107 either <package>libc6</package> (>= 2.1.3-13), or on
5108 <package>base-files</package> (>= 2.2.0), or on later
5109 versions of either one of these packages.
5115 <heading>Users and groups</heading>
5118 <heading>Introduction</heading>
5120 The Debian system can be configured to use either plain or
5125 Some user ids (UIDs) and group ids (GIDs) are reserved
5126 globally for use by certain packages. Because some
5127 packages need to include files which are owned by these
5128 users or groups, or need the ids compiled into binaries,
5129 these ids must be used on any Debian system only for the
5130 purpose for which they are allocated. This is a serious
5131 restriction, and we should avoid getting in the way of
5132 local administration policies. In particular, many sites
5133 allocate users and/or local system groups starting at 100.
5137 Apart from this we should have dynamically allocated ids,
5138 which should by default be arranged in some sensible
5139 order, but the behavior should be configurable.
5143 Packages other than <tt>base-passwd</tt> must not modify
5144 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5145 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5150 <heading>UID and GID classes</heading>
5152 The UID and GID numbers are divided into classes as
5158 Globally allocated by the Debian project, the same
5159 on every Debian system. These ids will appear in
5160 the <file>passwd</file> and <file>group</file> files of all
5161 Debian systems, new ids in this range being added
5162 automatically as the <tt>base-passwd</tt> package is
5167 Packages which need a single statically allocated
5168 uid or gid should use one of these; their
5169 maintainers should ask the <tt>base-passwd</tt>
5177 Dynamically allocated system users and groups.
5178 Packages which need a user or group, but can have
5179 this user or group allocated dynamically and
5180 differently on each system, should use <tt>adduser
5181 --system</tt> to create the group and/or user.
5182 <prgn>adduser</prgn> will check for the existence of
5183 the user or group, and if necessary choose an unused
5184 id based on the ranges specified in
5185 <file>adduser.conf</file>.
5189 <tag>1000-29999:</tag>
5192 Dynamically allocated user accounts. By default
5193 <prgn>adduser</prgn> will choose UIDs and GIDs for
5194 user accounts in this range, though
5195 <file>adduser.conf</file> may be used to modify this
5200 <tag>30000-59999:</tag>
5205 <tag>60000-64999:</tag>
5208 Globally allocated by the Debian project, but only
5209 created on demand. The ids are allocated centrally
5210 and statically, but the actual accounts are only
5211 created on users' systems on demand.
5215 These ids are for packages which are obscure or
5216 which require many statically-allocated ids. These
5217 packages should check for and create the accounts in
5218 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5219 <prgn>adduser</prgn> if it has this facility) if
5220 necessary. Packages which are likely to require
5221 further allocations should have a "hole" left after
5222 them in the allocation, to give them room to
5227 <tag>65000-65533:</tag>
5235 User <tt>nobody</tt>. The corresponding gid refers
5236 to the group <tt>nogroup</tt>.
5243 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5244 not</em> be used, because it is the error return
5253 <sect id="sysvinit">
5254 <heading>System run levels and <file>init.d</file> scripts</heading>
5256 <sect1 id="/etc/init.d">
5257 <heading>Introduction</heading>
5260 The <file>/etc/init.d</file> directory contains the scripts
5261 executed by <prgn>init</prgn> at boot time and when the
5262 init state (or "runlevel") is changed (see <manref
5263 name="init" section="8">).
5267 There are at least two different, yet functionally
5268 equivalent, ways of handling these scripts. For the sake
5269 of simplicity, this document describes only the symbolic
5270 link method. However, it must not be assumed by maintainer
5271 scripts that this method is being used, and any automated
5272 manipulation of the various runlevel behaviours by
5273 maintainer scripts must be performed using
5274 <prgn>update-rc.d</prgn> as described below and not by
5275 manually installing or removing symlinks. For information
5276 on the implementation details of the other method,
5277 implemented in the <tt>file-rc</tt> package, please refer
5278 to the documentation of that package.
5282 These scripts are referenced by symbolic links in the
5283 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5284 runlevels, <prgn>init</prgn> looks in the directory
5285 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5286 execute, where <tt><var>n</var></tt> is the runlevel that
5287 is being changed to, or <tt>S</tt> for the boot-up
5292 The names of the links all have the form
5293 <file>S<var>mm</var><var>script</var></file> or
5294 <file>K<var>mm</var><var>script</var></file> where
5295 <var>mm</var> is a two-digit number and <var>script</var>
5296 is the name of the script (this should be the same as the
5297 name of the actual script in <file>/etc/init.d</file>).
5301 When <prgn>init</prgn> changes runlevel first the targets
5302 of the links whose names start with a <tt>K</tt> are
5303 executed, each with the single argument <tt>stop</tt>,
5304 followed by the scripts prefixed with an <tt>S</tt>, each
5305 with the single argument <tt>start</tt>. (The links are
5306 those in the <file>/etc/rc<var>n</var>.d</file> directory
5307 corresponding to the new runlevel.) The <tt>K</tt> links
5308 are responsible for killing services and the <tt>S</tt>
5309 link for starting services upon entering the runlevel.
5313 For example, if we are changing from runlevel 2 to
5314 runlevel 3, init will first execute all of the <tt>K</tt>
5315 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
5316 all of the <tt>S</tt> prefixed scripts in that directory.
5317 The links starting with <tt>K</tt> will cause the
5318 referred-to file to be executed with an argument of
5319 <tt>stop</tt>, and the <tt>S</tt> links with an argument
5324 The two-digit number <var>mm</var> is used to determine
5325 the order in which to run the scripts: low-numbered links
5326 have their scripts run first. For example, the
5327 <tt>K20</tt> scripts will be executed before the
5328 <tt>K30</tt> scripts. This is used when a certain service
5329 must be started before another. For example, the name
5330 server <prgn>bind</prgn> might need to be started before
5331 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
5332 can set up its access lists. In this case, the script
5333 that starts <prgn>bind</prgn> would have a lower number
5334 than the script that starts <prgn>inn</prgn> so that it
5336 <example compact="compact">
5343 The two runlevels 0 (halt) and 6 (reboot) are slightly
5344 different. In these runlevels, the links with an
5345 <tt>S</tt> prefix are still called after those with a
5346 <tt>K</tt> prefix, but they too are called with the single
5347 argument <tt>stop</tt>.
5351 Also, if the script name ends <tt>.sh</tt>, the script
5352 will be sourced in runlevel <tt>S</tt> rather that being
5353 run in a forked subprocess, but will be explicitly run by
5354 <prgn>sh</prgn> in all other runlevels.
5359 <heading>Writing the scripts</heading>
5362 Packages that include daemons for system services should
5363 place scripts in <file>/etc/init.d</file> to start or stop
5364 services at boot time or during a change of runlevel.
5365 These scripts should be named
5366 <file>/etc/init.d/<var>package</var></file>, and they should
5367 accept one argument, saying what to do:
5370 <tag><tt>start</tt></tag>
5371 <item>start the service,</item>
5373 <tag><tt>stop</tt></tag>
5374 <item>stop the service,</item>
5376 <tag><tt>restart</tt></tag>
5377 <item>stop and restart the service if it's already running,
5378 otherwise start the service</item>
5380 <tag><tt>reload</tt></tag>
5381 <item><p>cause the configuration of the service to be
5382 reloaded without actually stopping and restarting
5385 <tag><tt>force-reload</tt></tag>
5386 <item>cause the configuration to be reloaded if the
5387 service supports this, otherwise restart the
5391 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
5392 <tt>force-reload</tt> options should be supported by all
5393 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
5398 The <file>init.d</file> scripts should ensure that they will
5399 behave sensibly if invoked with <tt>start</tt> when the
5400 service is already running, or with <tt>stop</tt> when it
5401 isn't, and that they don't kill unfortunately-named user
5402 processes. The best way to achieve this is usually to use
5403 <prgn>start-stop-daemon</prgn>.
5407 If a service reloads its configuration automatically (as
5408 in the case of <prgn>cron</prgn>, for example), the
5409 <tt>reload</tt> option of the <file>init.d</file> script
5410 should behave as if the configuration has been reloaded
5415 The <file>/etc/init.d</file> scripts must be treated as
5416 configuration files, either (if they are present in the
5417 package, that is, in the .deb file) by marking them as
5418 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
5419 by managing them correctly in the maintainer scripts (see
5420 <ref id="config-files">). This is important since we want
5421 to give the local system administrator the chance to adapt
5422 the scripts to the local system, e.g., to disable a
5423 service without de-installing the package, or to specify
5424 some special command line options when starting a service,
5425 while making sure her changes aren't lost during the next
5430 These scripts should not fail obscurely when the
5431 configuration files remain but the package has been
5432 removed, as configuration files remain on the system after
5433 the package has been removed. Only when <prgn>dpkg</prgn>
5434 is executed with the <tt>--purge</tt> option will
5435 configuration files be removed. In particular, as the
5436 <file>/etc/init.d/<var>package</var></file> script itself is
5437 usually a <tt>conffile</tt>, it will remain on the system
5438 if the package is removed but not purged. Therefore, you
5439 should include a <tt>test</tt> statement at the top of the
5441 <example compact="compact">
5442 test -f <var>program-executed-later-in-script</var> || exit 0
5447 Often there are some variables in the <file>init.d</file>
5448 scripts whose values control the behaviour of the scripts,
5449 and which a system administrator is likely to want to
5450 change. As the scripts themselves are frequently
5451 <tt>conffile</tt>s, modifying them requires that the
5452 administrator merge in their changes each time the package
5453 is upgraded and the <tt>conffile</tt> changes. To ease
5454 the burden on the system administrator, such configurable
5455 values should not be placed directly in the script.
5456 Instead, they should be placed in a file in
5457 <file>/etc/default</file>, which typically will have the same
5458 base name as the <file>init.d</file> script. This extra file
5459 should be sourced by the script when the script runs. It
5460 must contain only variable settings and comments in POSIX
5461 <prgn>sh</prgn> format. It may either be a
5462 <tt>conffile</tt> or a configuration file maintained by
5463 the package maintainer scripts. See <ref id="config-files">
5468 To ensure that vital configurable values are always
5469 available, the <file>init.d</file> script should set default
5470 values for each of the shell variables it uses, either
5471 before sourcing the <file>/etc/default/</file> file or
5472 afterwards using something like the <tt>:
5473 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
5474 script must behave sensibly and not fail if the
5475 <file>/etc/default</file> file is deleted.
5480 <heading>Interfacing with the initscript system</heading>
5483 Maintainers should use the abstraction layer provided by
5484 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
5485 programs to deal with initscripts in their packages'
5486 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
5487 and <prgn>postrm</prgn>.
5491 Directly managing the /etc/rc?.d links and directly
5492 invoking the <file>/etc/init.d/</file> initscripts should
5493 be done only by packages providing the initscript
5494 subsystem (such as <prgn>sysvinit</prgn> and
5495 <prgn>file-rc</prgn>).
5499 <heading>Managing the links</heading>
5502 The program <prgn>update-rc.d</prgn> is provided for
5503 package maintainers to arrange for the proper creation and
5504 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
5505 or their functional equivalent if another method is being
5506 used. This may be used by maintainers in their packages'
5507 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
5511 You must not include any <file>/etc/rc<var>n</var>.d</file>
5512 symbolic links in the actual archive or manually create or
5513 remove the symbolic links in maintainer scripts; you must
5514 use the <prgn>update-rc.d</prgn> program instead. (The
5515 former will fail if an alternative method of maintaining
5516 runlevel information is being used.) You must not include
5517 the <file>/etc/rc<var>n</var>.d</file> directories themselves
5518 in the archive either. (Only the <tt>sysvinit</tt>
5523 By default <prgn>update-rc.d</prgn> will start services in
5524 each of the multi-user state runlevels (2, 3, 4, and 5)
5525 and stop them in the halt runlevel (0), the single-user
5526 runlevel (1) and the reboot runlevel (6). The system
5527 administrator will have the opportunity to customize
5528 runlevels by simply adding, moving, or removing the
5529 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
5530 symbolic links are being used, or by modifying
5531 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
5536 To get the default behavior for your package, put in your
5537 <prgn>postinst</prgn> script
5538 <example compact="compact">
5539 update-rc.d <var>package</var> defaults
5541 and in your <prgn>postrm</prgn>
5542 <example compact="compact">
5543 if [ "$1" = purge ]; then
5544 update-rc.d <var>package</var> remove
5546 </example>. Note that if your package changes runlevels
5547 or priority, you may have to remove and recreate the links,
5548 since otherwise the old links may persist. Refer to the
5549 documentation of <prgn>update-rc.d</prgn>.
5553 This will use a default sequence number of 20. If it does
5554 not matter when or in which order the <file>init.d</file>
5555 script is run, use this default. If it does, then you
5556 should talk to the maintainer of the <prgn>sysvinit</prgn>
5557 package or post to <tt>debian-devel</tt>, and they will
5558 help you choose a number.
5562 For more information about using <tt>update-rc.d</tt>,
5563 please consult its manpage <manref name="update-rc.d"
5569 <heading>Running initscripts</heading>
5571 The program <prgn>invoke-rc.d</prgn> is provided to make
5572 it easier for package maintainers to properly invoke an
5573 initscript, obeying runlevel and other locally-defined
5574 constraints that might limit a package's right to start,
5575 stop and otherwise manage services. This program may be
5576 used by maintainers in their packages' scripts.
5580 The use of <prgn>invoke-rc.d</prgn> to invoke the
5581 <file>/etc/init.d/*</file> initscripts is strongly
5582 recommended<footnote>
5583 In the future, the use of invoke-rc.d to invoke
5584 initscripts shall be made mandatory. Maintainers are
5585 advised to switch to invoke-rc.d as soon as
5587 </footnote>, instead of calling them directly.
5591 By default, <prgn>invoke-rc.d</prgn> will pass any
5592 action requests (start, stop, reload, restart...) to the
5593 <file>/etc/init.d</file> script, filtering out requests
5594 to start or restart a service out of its intended
5599 Most packages will simply need to change:
5600 <example compact="compact">/etc/init.d/<package>
5601 <action></example> in their <prgn>postinst</prgn>
5602 and <prgn>prerm</prgn> scripts to:
5603 <example compact="compact">
5604 if [ -x /usr/sbin/invoke-rc.d ] ; then
5605 invoke-rc.d <var>package</var> <action>
5607 /etc/init.d/<var>package</var> <action>
5613 A package should register its initscript services using
5614 <prgn>update-rc.d</prgn> before it tries to invoke them
5615 using <prgn>invoke-rc.d</prgn>. Invocation of
5616 unregistered services may fail.
5620 For more information about using
5621 <prgn>invoke-rc.d</prgn>, please consult its manpage
5622 <manref name="invoke-rc.d" section="8">.
5628 <heading>Boot-time initialization</heading>
5631 There used to be another directory, <file>/etc/rc.boot</file>,
5632 which contained scripts which were run once per machine
5633 boot. This has been deprecated in favour of links from
5634 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
5635 described in <ref id="/etc/init.d">. Packages must not
5636 place files in <file>/etc/rc.boot</file>.
5641 <heading>Example</heading>
5644 The <prgn>bind</prgn> DNS (nameserver) package wants to
5645 make sure that the nameserver is running in multiuser
5646 runlevels, and is properly shut down with the system. It
5647 puts a script in <file>/etc/init.d</file>, naming the script
5648 appropriately <tt>bind</tt>. As you can see, the script
5649 interprets the argument <tt>reload</tt> to send the
5650 nameserver a <tt>HUP</tt> signal (causing it to reload its
5651 configuration); this way the system administrator can say
5652 <tt>/etc/init.d/bind reload</tt> to reload the name
5653 server. The script has one configurable value, which can
5654 be used to pass parameters to the named program at
5655 startup; this value is read from
5656 <file>/etc/default/bind</file> (see below).
5660 <example compact="compact">
5663 # Original version by Robert Leslie
5664 # <rob@mars.org>, edited by iwj and cs
5666 test -x /usr/sbin/named || exit 0
5668 # Source defaults file.
5670 if [ -f /etc/default/bind ]; then
5677 echo -n "Starting domain name service: named"
5678 start-stop-daemon --start --quiet --exec /usr/sbin/named \
5683 echo -n "Stopping domain name service: named"
5684 start-stop-daemon --stop --quiet \
5685 --pidfile /var/run/named.pid --exec /usr/sbin/named
5689 echo -n "Restarting domain name service: named"
5690 start-stop-daemon --stop --quiet \
5691 --pidfile /var/run/named.pid --exec /usr/sbin/named
5692 start-stop-daemon --start --verbose --exec /usr/sbin/named \
5696 force-reload|reload)
5697 echo -n "Reloading configuration of domain name service: named"
5698 start-stop-daemon --stop --signal 1 --quiet \
5699 --pidfile /var/run/named.pid --exec /usr/sbin/named
5703 echo "Usage: /etc/init.d/bind " \
5704 " {start|stop|restart|reload|force-reload}" >&2
5714 Complementing the above init script is a configuration
5715 file <file>/etc/default/bind</file>, which contains
5716 configurable parameters used by the script. This would be
5717 created by the <prgn>postinst</prgn> script if it was not
5718 already present, and removed on purge by the
5719 <prgn>postrm</prgn> script.
5720 <example compact="compact">
5721 # Specified parameters to pass to named. See named(8).
5722 # You may uncomment the following line, and edit to taste.
5728 Another example on which you can base your
5729 <file>/etc/init.d</file> scripts is found in
5730 <file>/etc/init.d/skeleton</file>.
5734 If this package is happy with the default setup from
5735 <prgn>update-rc.d</prgn>, namely an ordering number of 20
5736 and having named running in all runlevels, it can say in
5737 its <prgn>postinst</prgn>:
5738 <example compact="compact">
5739 update-rc.d bind defaults >/dev/null
5741 And in its <prgn>postrm</prgn>, to remove the links when the
5743 <example compact="compact">
5744 if [ "$1" = purge ]; then
5745 update-rc.d bind remove >/dev/null
5753 <heading>Console messages from <file>init.d</file> scripts</heading>
5756 This section describes the formats to be used for messages
5757 written to standard output by the <file>/etc/init.d</file>
5758 scripts. The intent is to improve the consistency of
5759 Debian's startup and shutdown look and feel. For this
5760 reason, please look very carefully at the details. We want
5761 the messages to have the same format in terms of wording,
5762 spaces, punctuation and case of letters.
5766 Here is a list of overall rules that you should use when you
5767 create output messages. They can be useful if you have a
5768 non-standard message that is not covered specifically in the
5775 Every message should fit in one line (fewer than 80
5776 characters), start with a capital letter and end with
5777 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
5781 If you want to express that the computer is working on
5782 something (that is, performing a specific task, not
5783 starting or stopping a program), we use an "ellipsis"
5784 (three dots: <tt>...</tt>). Note that we don't insert
5785 spaces before or after the dots. If the task has been
5786 completed we write <tt>done.</tt> and a line feed.
5790 Design your messages as if the computer is telling you
5791 what he is doing (let him be polite :-), but don't
5792 mention "him" directly. For example, if you think of
5794 <example compact="compact">
5795 I'm starting network daemons: nfsd mountd.
5798 <example compact="compact">
5799 Starting network daemons: nfsd mountd.
5806 There are standard message formats for the following
5807 situations. They should be used by the <tt>init.d</tt>
5814 <p>When daemons are started</p>
5817 If your script starts one or more daemons, the output
5818 should look like this (a single line, no leading
5820 <example compact="compact">
5821 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
5823 The <var>description</var> should describe the
5824 subsystem the daemon or set of daemons are part of,
5825 while <var>daemon-1</var> up to <var>daemon-n</var>
5826 denote each daemon's name (typically the file name of
5831 For example, the output of <file>/etc/init.d/lpd</file>
5833 <example compact="compact">
5834 Starting printer spooler: lpd.
5839 This can be achieved by saying
5840 <example compact="compact">
5841 echo -n "Starting printer spooler: lpd"
5842 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
5845 in the script. If you have more than one daemon to
5846 start, you should do the following:
5847 <example compact="compact">
5848 echo -n "Starting remote file system services:"
5849 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
5850 echo -n " mountd"; start-stop-daemon --start --quiet mountd
5851 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
5854 This makes it possible for the user to see what takes
5855 so long and when the final daemon has been started.
5856 You should be careful where to put spaces: in the
5857 example above the system administrator can easily
5858 comment out a line if he don't wants to start a
5859 specific daemon, while the displayed message still
5865 <p>When a system parameter is being set</p>
5868 If you have to set up different system parameters
5869 during the system boot, you should use this format:
5870 <example compact="compact">
5871 Setting <var>parameter</var> to "<var>value</var>".
5876 You can use a statement such as the following to get
5878 <example compact="compact">
5879 echo "Setting DNS domainname to \"$domainname\"."
5884 Note that the same symbol (<tt>"</tt>) is used for the left
5885 and right quotation marks. A grave accent (<tt>`</tt>) is
5886 not a quote character; neither is an apostrophe
5892 <p>When a daemon is stopped or restarted</p>
5895 When you stop or restart a daemon, you should issue a
5896 message identical to the startup message, except that
5897 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
5898 or <tt>Restarting</tt> respectively.
5902 For example, stopping the printer daemon will like
5904 <example compact="compact">
5905 Stopping printer spooler: lpd.
5911 <p>When something is executed</p>
5914 There are several examples where you have to run a
5915 program at system startup or shutdown to perform a
5916 specific task, for example, setting the system's clock
5917 using <prgn>netdate</prgn> or killing all processes
5918 when the system shuts down. Your message should look
5920 <example compact="compact">
5921 Doing something very useful...done.
5923 You should print the <tt>done.</tt> immediately after
5924 the job has been completed, so that the user is
5925 informed why she has to wait. You can get this
5927 <example compact="compact">
5928 echo -n "Doing something very useful..."
5937 <p>When the configuration is reloaded</p>
5940 When a daemon is forced to reload its configuration
5941 files you should use the following format:
5942 <example compact="compact">
5943 Reloading <var>description</var> configuration...done.
5945 where <var>description</var> is the same as in the
5946 daemon starting message.
5954 <heading>Cron jobs</heading>
5957 Packages must not modify the configuration file
5958 <file>/etc/crontab</file>, and they must not modify the files in
5959 <file>/var/spool/cron/crontabs</file>.</p>
5962 If a package wants to install a job that has to be executed
5963 via cron, it should place a file with the name of the
5964 package in one or more of the following directories:
5965 <example compact="compact">
5970 As these directory names imply, the files within them are
5971 executed on a daily, weekly, or monthly basis,
5972 respectively. The exact times are listed in
5973 <file>/etc/crontab</file>.</p>
5976 All files installed in any of these directories must be
5977 scripts (e.g., shell scripts or Perl scripts) so that they
5978 can easily be modified by the local system administrator.
5979 In addition, they should be treated as configuration
5984 If a certain job has to be executed more frequently than
5985 daily, the package should install a file
5986 <file>/etc/cron.d/<var>package</var></file>. This file uses the
5987 same syntax as <file>/etc/crontab</file> and is processed by
5988 <prgn>cron</prgn> automatically. The file must also be
5989 treated as a configuration file. (Note that entries in the
5990 <file>/etc/cron.d</file> directory are not handled by
5991 <prgn>anacron</prgn>. Thus, you should only use this
5992 directory for jobs which may be skipped if the system is not
5996 The scripts or crontab entries in these directories should
5997 check if all necessary programs are installed before they
5998 try to execute them. Otherwise, problems will arise when a
5999 package was removed but not purged since configuration files
6000 are kept on the system in this situation.</p>
6004 <heading>Menus</heading>
6007 The Debian <tt>menu</tt> package provides a standard
6008 interface between packages providing applications and
6009 documents, and <em>menu programs</em> (either X window
6010 managers or text-based menu programs such as
6011 <prgn>pdmenu</prgn>).
6015 All packages that provide applications that need not be
6016 passed any special command line arguments for normal
6017 operation should register a menu entry for those
6018 applications, so that users of the <tt>menu</tt> package
6019 will automatically get menu entries in their window
6020 managers, as well in shells like <tt>pdmenu</tt>.
6024 Menu entries should follow the current menu policy.
6028 The menu policy can be found in the <tt>menu-policy</tt>
6029 files in the <tt>debian-policy</tt> package.
6030 It is also available from the Debian web mirrors at
6031 <tt><url name="/doc/packaging-manuals/menu-policy/"
6032 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>
6033 and from the Debian archive mirrors at
6034 <tt><url name="/doc/package-developer/menu-policy.txt.gz"
6035 id="http://ftp.debian.org/debian/doc/package-developer/menu-policy.txt.gz"></tt>.
6039 Please also refer to the <em>Debian Menu System</em>
6040 documentation that comes with the <tt>menu</tt> package for
6041 information about how to register your applications and web
6047 <heading>Multimedia handlers</heading>
6050 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6051 is a mechanism for encoding files and data streams and
6052 providing meta-information about them, in particular their
6053 type (e.g. audio or video) and format (e.g. PNG, HTML,
6058 Registration of MIME type handlers allows programs like mail
6059 user agents and web browsers to invoke these handlers to
6060 view, edit or display MIME types they don't support directly.
6064 Packages which provide the ability to view/show/play,
6065 compose, edit or print MIME types should register themselves
6066 as such following the current MIME support policy.
6070 The MIME support policy can be found in the <tt>mime-policy</tt>
6071 files in the <tt>debian-policy</tt> package.
6072 It is also available from the Debian web mirrors at
6073 <tt><url name="/doc/packaging-manuals/mime-policy/"
6074 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>
6075 and from the Debian archive mirrors at
6076 <tt><url name="/doc/package-developer/mime-policy.txt.gz"
6077 id="http://ftp.debian.org/debian/doc/package-developer/mime-policy.txt.gz"></tt>.
6083 <heading>Keyboard configuration</heading>
6086 To achieve a consistent keyboard configuration so that all
6087 applications interpret a keyboard event the same way, all
6088 programs in the Debian distribution must be configured to
6089 comply with the following guidelines.
6093 The following keys must have the specified interpretations:
6096 <tag><tt><--</tt></tag>
6097 <item>delete the character to the left of the cursor</item>
6099 <tag><tt>Delete</tt></tag>
6100 <item>delete the character to the right of the cursor</item>
6102 <tag><tt>Control+H</tt></tag>
6103 <item>emacs: the help prefix</item>
6106 The interpretation of any keyboard events should be
6107 independent of the terminal that is used, be it a virtual
6108 console, an X terminal emulator, an rlogin/telnet session,
6113 The following list explains how the different programs
6114 should be set up to achieve this:
6120 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6124 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6128 X translations are set up to make
6129 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6130 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6131 is the vt220 escape code for the "delete character"
6132 key). This must be done by loading the X resources
6133 using <prgn>xrdb</prgn> on all local X displays, not
6134 using the application defaults, so that the
6135 translation resources used correspond to the
6136 <prgn>xmodmap</prgn> settings.
6140 The Linux console is configured to make
6141 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6142 generate <tt>ESC [ 3 ~</tt>.
6146 X applications are configured so that <tt><</tt>
6147 deletes left, and <tt>Delete</tt> deletes right. Motif
6148 applications already work like this.
6152 Terminals should have <tt>stty erase ^?</tt> .
6156 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6157 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6158 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6162 Emacs is programmed to map <tt>KB_Backspace</tt> or
6163 the <tt>stty erase</tt> character to
6164 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6165 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6166 <tt>^H</tt> to <tt>help</tt> as always.
6170 Other applications use the <tt>stty erase</tt>
6171 character and <tt>kdch1</tt> for the two delete keys,
6172 with ASCII DEL being "delete previous character" and
6173 <tt>kdch1</tt> being "delete character under
6181 This will solve the problem except for the following
6188 Some terminals have a <tt><--</tt> key that cannot
6189 be made to produce anything except <tt>^H</tt>. On
6190 these terminals Emacs help will be unavailable on
6191 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6192 character takes precedence in Emacs, and has been set
6193 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6194 available) can be used instead.
6198 Some operating systems use <tt>^H</tt> for <tt>stty
6199 erase</tt>. However, modern telnet versions and all
6200 rlogin versions propagate <tt>stty</tt> settings, and
6201 almost all UNIX versions honour <tt>stty erase</tt>.
6202 Where the <tt>stty</tt> settings are not propagated
6203 correctly, things can be made to work by using
6204 <tt>stty</tt> manually.
6208 Some systems (including previous Debian versions) use
6209 <prgn>xmodmap</prgn> to arrange for both
6210 <tt><--</tt> and <tt>Delete</tt> to generate
6211 <tt>KB_Delete</tt>. We can change the behavior of
6212 their X clients using the same X resources that we use
6213 to do it for our own clients, or configure our clients
6214 using their resources when things are the other way
6215 around. On displays configured like this
6216 <tt>Delete</tt> will not work, but <tt><--</tt>
6221 Some operating systems have different <tt>kdch1</tt>
6222 settings in their <tt>terminfo</tt> database for
6223 <tt>xterm</tt> and others. On these systems the
6224 <tt>Delete</tt> key will not work correctly when you
6225 log in from a system conforming to our policy, but
6226 <tt><--</tt> will.
6233 <heading>Environment variables</heading>
6236 A program must not depend on environment variables to get
6237 reasonable defaults. (That's because these environment
6238 variables would have to be set in a system-wide
6239 configuration file like <file>/etc/profile</file>, which is not
6240 supported by all shells.)
6244 If a program usually depends on environment variables for its
6245 configuration, the program should be changed to fall back to
6246 a reasonable default configuration if these environment
6247 variables are not present. If this cannot be done easily
6248 (e.g., if the source code of a non-free program is not
6249 available), the program must be replaced by a small
6250 "wrapper" shell script which sets the environment variables
6251 if they are not already defined, and calls the original program.
6255 Here is an example of a wrapper script for this purpose:
6257 <example compact="compact">
6259 BAR=${BAR:-/var/lib/fubar}
6261 exec /usr/lib/foo/foo "$@"
6266 Furthermore, as <file>/etc/profile</file> is a configuration
6267 file of the <prgn>base-files</prgn> package, other packages must
6268 not put any environment variables or other commands into that
6277 <heading>Files</heading>
6280 <heading>Binaries</heading>
6283 Two different packages must not install programs with
6284 different functionality but with the same filenames. (The
6285 case of two programs having the same functionality but
6286 different implementations is handled via "alternatives" or
6287 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6288 <ref id="conflicts"> respectively.) If this case happens,
6289 one of the programs must be renamed. The maintainers should
6290 report this to the <tt>debian-devel</tt> mailing list and
6291 try to find a consensus about which program will have to be
6292 renamed. If a consensus cannot be reached, <em>both</em>
6293 programs must be renamed.
6297 By default, when a package is being built, any binaries
6298 created should include debugging information, as well as
6299 being compiled with optimization. You should also turn on
6300 as many reasonable compilation warnings as possible; this
6301 makes life easier for porters, who can then look at build
6302 logs for possible problems. For the C programming language,
6303 this means the following compilation parameters should be
6305 <example compact="compact">
6307 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6309 install -s # (or use strip on the files in debian/tmp)
6314 Note that by default all installed binaries should be stripped,
6315 either by using the <tt>-s</tt> flag to
6316 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6317 the binaries after they have been copied into
6318 <file>debian/tmp</file> but before the tree is made into a
6323 Although binaries in the build tree should be compiled with
6324 debugging information by default, it can often be difficult
6325 to debug programs if they are also subjected to compiler
6326 optimization. For this reason, it is recommended to support
6327 the standardized environment
6328 variable <tt>DEB_BUILD_OPTIONS</tt>. This variable can
6329 contain several flags to change how a package is compiled
6337 The presence of this string means that the package
6338 should be compiled with a minimum of optimization.
6339 For C programs, it is best to add <tt>-O0</tt>
6340 to <tt>CFLAGS</tt> (although this is usually the
6341 default). Some programs might fail to build or run at
6342 this level of optimization; it may be necessary to
6343 use <tt>-O1</tt>, for example.
6347 This string means that the debugging symbols should
6348 not be stripped from the binary during installation,
6349 so that debugging information may be included in the package.
6355 The following makefile snippet is an example of how one may
6356 implement the build options; you will probably have to
6357 massage this example in order to make it work for your
6359 <example compact="compact">
6362 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
6363 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
6364 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
6365 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
6367 ifneq (,$(findstring noopt,$(DEB_BUILD_OPTIONS)))
6372 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
6373 INSTALL_PROGRAM += -s
6379 It is up to the package maintainer to decide what
6380 compilation options are best for the package. Certain
6381 binaries (such as computationally-intensive programs) will
6382 function better with certain flags (<tt>-O3</tt>, for
6383 example); feel free to use them. Please use good judgment
6384 here. Don't use flags for the sake of it; only use them
6385 if there is good reason to do so. Feel free to override
6386 the upstream author's ideas about which compilation
6387 options are best: they are often inappropriate for our
6393 <sect id="libraries">
6394 <heading>Libraries</heading>
6397 The shared version of a library must be compiled with
6398 <tt>-fPIC</tt>, and the static version must not be. In other
6399 words, each source unit (<tt>*.c</tt>, for example, for C files)
6400 will need to be compiled twice.
6404 You must specify the gcc option <tt>-D_REENTRANT</tt>
6405 when building a library (either static or shared) to make
6406 the library compatible with LinuxThreads.
6410 Although not enforced by the build tools, shared libraries
6411 must be linked against all libraries that they use symbols from
6412 in the same way that binaries are. This ensures the correct
6413 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
6414 system and guarantees that all libraries can be safely opened
6415 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
6416 option <tt>-Wl,-z,defs</tt> when building a shared library.
6417 Since this option enforces symbol resolution at build time,
6418 a missing library reference will be caught early as a fatal
6423 All installed shared libraries should be stripped with
6424 <example compact="compact">
6425 strip --strip-unneeded <var>your-lib</var>
6427 (The option <tt>--strip-unneeded</tt> makes
6428 <prgn>strip</prgn> remove only the symbols which aren't
6429 needed for relocation processing.) Shared libraries can
6430 function perfectly well when stripped, since the symbols for
6431 dynamic linking are in a separate part of the ELF object
6433 You might also want to use the options
6434 <tt>--remove-section=.comment</tt> and
6435 <tt>--remove-section=.note</tt> on both shared libraries
6436 and executables, and <tt>--strip-debug</tt> on static
6442 Note that under some circumstances it may be useful to
6443 install a shared library unstripped, for example when
6444 building a separate package to support debugging.
6448 Shared object files (often <file>.so</file> files) that are not
6449 public libraries, that is, they are not meant to be linked
6450 to by third party executables (binaries of other packages),
6451 should be installed in subdirectories of the
6452 <file>/usr/lib</file> directory. Such files are exempt from the
6453 rules that govern ordinary shared libraries, except that
6454 they must not be installed executable and should be
6456 A common example are the so-called "plug-ins",
6457 internal shared objects that are dynamically loaded by
6458 programs using <manref name="dlopen" section="3">.
6463 Packages containing shared libraries that may be linked to
6464 by other packages' binaries, but which for some
6465 <em>compelling</em> reason can not be installed in
6466 <file>/usr/lib</file> directory, may install the shared library
6467 files in subdirectories of the <file>/usr/lib</file> directory,
6468 in which case they should arrange to add that directory in
6469 <file>/etc/ld.so.conf</file> in the package's post-installation
6470 script, and remove it in the package's post-removal script.
6474 An ever increasing number of packages are using
6475 <prgn>libtool</prgn> to do their linking. The latest GNU
6476 libtools (>= 1.3a) can take advantage of the metadata in the
6477 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
6478 files). The main advantage of <prgn>libtool</prgn>'s
6479 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
6480 store and subsequently access metadata with respect to the
6481 libraries it builds. <prgn>libtool</prgn> will search for
6482 those files, which contain a lot of useful information about
6483 a library (such as library dependency information for static
6484 linking). Also, they're <em>essential</em> for programs
6485 using <tt>libltdl</tt>.<footnote>
6486 Although <prgn>libtool</prgn> is fully capable of
6487 linking against shared libraries which don't have
6488 <tt>.la</tt> files, as it is a mere shell script it can
6489 add considerably to the build time of a
6490 <prgn>libtool</prgn>-using package if that shell script
6491 has to derive all this information from first principles
6492 for each library every time it is linked. With the
6493 advent of <prgn>libtool</prgn> version 1.4 (and to a
6494 lesser extent <prgn>libtool</prgn> version 1.3), the
6495 <file>.la</file> files also store information about
6496 inter-library dependencies which cannot necessarily be
6497 derived after the <file>.la</file> file is deleted.
6502 Packages that use <prgn>libtool</prgn> to create shared
6503 libraries should include the <file>.la</file> files in the
6504 <tt>-dev</tt> package, unless the package relies on
6505 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
6506 the <tt>.la</tt> files must go in the run-time library
6511 You must make sure that you use only released versions of
6512 shared libraries to build your packages; otherwise other
6513 users will not be able to run your binaries
6514 properly. Producing source packages that depend on
6515 unreleased compilers is also usually a bad
6522 <heading>Shared libraries</heading>
6524 This section has moved to <ref id="sharedlibs">.
6530 <heading>Scripts</heading>
6533 All command scripts, including the package maintainer
6534 scripts inside the package and used by <prgn>dpkg</prgn>,
6535 should have a <tt>#!</tt> line naming the shell to be used
6540 In the case of Perl scripts this should be
6541 <tt>#!/usr/bin/perl</tt>.
6545 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
6546 should almost certainly start with <tt>set -e</tt> so that
6547 errors are detected. Every script should use
6548 <tt>set -e</tt> or check the exit status of <em>every</em>
6553 The standard shell interpreter <file>/bin/sh</file> can be a
6554 symbolic link to any POSIX compatible shell, if <tt>echo
6555 -n</tt> does not generate a newline.<footnote>
6556 Debian policy specifies POSIX behavior for
6557 <file>/bin/sh</file>, but <tt>echo -n</tt> has widespread
6558 use in the Linux community (in particular including this
6559 policy, the Linux kernel source, many Debian scripts,
6560 etc.). This <tt>echo -n</tt> mechanism is valid but not
6561 required under POSIX, hence this explicit addition.
6562 Also, rumour has it that this shall be mandated under
6565 Thus, shell scripts specifying <file>/bin/sh</file> as
6566 interpreter should only use POSIX features. If a script
6567 requires non-POSIX features from the shell interpreter, the
6568 appropriate shell must be specified in the first line of the
6569 script (e.g., <tt>#!/bin/bash</tt>) and the package must
6570 depend on the package providing the shell (unless the shell
6571 package is marked "Essential", as in the case of
6576 You may wish to restrict your script to POSIX features when
6577 possible so that it may use <file>/bin/sh</file> as its
6578 interpreter. If your script works with <prgn>dash</prgn>
6579 (originally called <prgn>ash</prgn>), it's probably POSIX
6580 compliant, but if you are in doubt, use
6581 <file>/bin/bash</file>.
6585 Perl scripts should check for errors when making any
6586 system calls, including <tt>open</tt>, <tt>print</tt>,
6587 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
6591 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
6592 scripting languages. See <em>Csh Programming Considered
6593 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
6594 can be found at <url id="http://language.perl.com/versus/csh.whynot">.
6595 If an upstream package comes with <prgn>csh</prgn> scripts
6596 then you must make sure that they start with
6597 <tt>#!/bin/csh</tt> and make your package depend on the
6598 <prgn>c-shell</prgn> virtual package.
6602 Any scripts which create files in world-writeable
6603 directories (e.g., in <file>/tmp</file>) must use a
6604 mechanism which will fail if a file with the same name
6609 The Debian base system provides the <prgn>tempfile</prgn>
6610 and <prgn>mktemp</prgn> utilities for use by scripts for
6617 <heading>Symbolic links</heading>
6620 In general, symbolic links within a top-level directory
6621 should be relative, and symbolic links pointing from one
6622 top-level directory into another should be absolute. (A
6623 top-level directory is a sub-directory of the root
6624 directory <file>/</file>.)
6628 In addition, symbolic links should be specified as short as
6629 possible, i.e., link targets like <file>foo/../bar</file> are
6634 Note that when creating a relative link using
6635 <prgn>ln</prgn> it is not necessary for the target of the
6636 link to exist relative to the working directory you're
6637 running <prgn>ln</prgn> from, nor is it necessary to change
6638 directory to the directory where the link is to be made.
6639 Simply include the string that should appear as the target
6640 of the link (this will be a pathname relative to the
6641 directory in which the link resides) as the first argument
6646 For example, in your <prgn>Makefile</prgn> or
6647 <file>debian/rules</file>, you can do things like:
6648 <example compact="compact">
6649 ln -fs gcc $(prefix)/bin/cc
6650 ln -fs gcc debian/tmp/usr/bin/cc
6651 ln -fs ../sbin/sendmail $(prefix)/bin/runq
6652 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
6657 A symbolic link pointing to a compressed file should always
6658 have the same file extension as the referenced file. (For
6659 example, if a file <file>foo.gz</file> is referenced by a
6660 symbolic link, the filename of the link has to end with
6661 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
6666 <heading>Device files</heading>
6669 Packages must not include device files in the package file
6674 If a package needs any special device files that are not
6675 included in the base system, it must call
6676 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
6677 after notifying the user<footnote>
6678 This notification could be done via a (low-priority)
6679 debconf message, or an echo (printf) statement.
6684 Packages must not remove any device files in the
6685 <prgn>postrm</prgn> or any other script. This is left to the
6686 system administrator.
6690 Debian uses the serial devices
6691 <file>/dev/ttyS*</file>. Programs using the old
6692 <file>/dev/cu*</file> devices should be changed to use
6693 <file>/dev/ttyS*</file>.
6697 <sect id="config-files">
6698 <heading>Configuration files</heading>
6701 <heading>Definitions</heading>
6705 <tag>configuration file</tag>
6707 A file that affects the operation of a program, or
6708 provides site- or host-specific information, or
6709 otherwise customizes the behavior of a program.
6710 Typically, configuration files are intended to be
6711 modified by the system administrator (if needed or
6712 desired) to conform to local policy or to provide
6713 more useful site-specific behavior.
6716 <tag><tt>conffile</tt></tag>
6718 A file listed in a package's <tt>conffiles</tt>
6719 file, and is treated specially by <prgn>dpkg</prgn>
6720 (see <ref id="configdetails">).
6726 The distinction between these two is important; they are
6727 not interchangeable concepts. Almost all
6728 <tt>conffile</tt>s are configuration files, but many
6729 configuration files are not <tt>conffiles</tt>.
6733 Note that a script that embeds configuration information
6734 (such as most of the files in <file>/etc/default</file> and
6735 <file>/etc/cron.{daily,weekly,monthly}</file>) is de-facto a
6736 configuration file and should be treated as such.
6741 <heading>Location</heading>
6744 Any configuration files created or used by your package
6745 must reside in <file>/etc</file>. If there are several,
6746 consider creating a subdirectory of <file>/etc</file>
6747 named after your package.
6751 If your package creates or uses configuration files
6752 outside of <file>/etc</file>, and it is not feasible to modify
6753 the package to use <file>/etc</file> directly, put the files
6754 in <file>/etc</file> and create symbolic links to those files
6755 from the location that the package requires.
6760 <heading>Behavior</heading>
6763 Configuration file handling must conform to the following
6765 <list compact="compact">
6767 local changes must be preserved during a package
6771 configuration files must be preserved when the
6772 package is removed, and only deleted when the
6779 The easy way to achieve this behavior is to make the
6780 configuration file a <tt>conffile</tt>. This is
6781 appropriate only if it is possible to distribute a default
6782 version that will work for most installations, although
6783 some system administrators may choose to modify it. This
6784 implies that the default version will be part of the
6785 package distribution, and must not be modified by the
6786 maintainer scripts during installation (or at any other
6791 In order to ensure that local changes are preserved
6792 correctly, no package may contain or make hard links to
6793 conffiles.<footnote>
6794 Rationale: There are two problems with hard links.
6795 The first is that some editors break the link while
6796 editing one of the files, so that the two files may
6797 unwittingly become unlinked and different. The second
6798 is that <prgn>dpkg</prgn> might break the hard link
6799 while upgrading <tt>conffile</tt>s.
6804 The other way to do it is via the maintainer scripts. In
6805 this case, the configuration file must not be listed as a
6806 <tt>conffile</tt> and must not be part of the package
6807 distribution. If the existence of a file is required for
6808 the package to be sensibly configured it is the
6809 responsibility of the package maintainer to provide
6810 maintainer scripts which correctly create, update and
6811 maintain the file and remove it on purge. (See <ref
6812 id="maintainerscripts"> for more information.) These
6813 scripts must be idempotent (i.e., must work correctly if
6814 <prgn>dpkg</prgn> needs to re-run them due to errors
6815 during installation or removal), must cope with all the
6816 variety of ways <prgn>dpkg</prgn> can call maintainer
6817 scripts, must not overwrite or otherwise mangle the user's
6818 configuration without asking, must not ask unnecessary
6819 questions (particularly during upgrades), and otherwise be
6824 The scripts are not required to configure every possible
6825 option for the package, but only those necessary to get
6826 the package running on a given system. Ideally the
6827 sysadmin should not have to do any configuration other
6828 than that done (semi-)automatically by the
6829 <prgn>postinst</prgn> script.
6833 A common practice is to create a script called
6834 <file><var>package</var>-configure</file> and have the
6835 package's <prgn>postinst</prgn> call it if and only if the
6836 configuration file does not already exist. In certain
6837 cases it is useful for there to be an example or template
6838 file which the maintainer scripts use. Such files should
6839 be in <file>/usr/share/<var>package</var></file> or
6840 <file>/usr/lib/<var>package</var></file> (depending on whether
6841 they are architecture-independent or not). There should
6842 be symbolic links to them from
6843 <file>/usr/share/doc/<var>package</var>/examples</file> if
6844 they are examples, and should be perfectly ordinary
6845 <prgn>dpkg</prgn>-handled files (<em>not</em>
6846 configuration files).
6850 These two styles of configuration file handling must
6851 not be mixed, for that way lies madness:
6852 <prgn>dpkg</prgn> will ask about overwriting the file
6853 every time the package is upgraded.
6858 <heading>Sharing configuration files</heading>
6861 Packages which specify the same file as a
6862 <tt>conffile</tt> must be tagged as <em>conflicting</em>
6863 with each other. (This is an instance of the general rule
6864 about not sharing files. Note that neither alternatives
6865 nor diversions are likely to be appropriate in this case;
6866 in particular, <prgn>dpkg</prgn> does not handle diverted
6867 <tt>conffile</tt>s well.)
6871 The maintainer scripts must not alter a <tt>conffile</tt>
6872 of <em>any</em> package, including the one the scripts
6877 If two or more packages use the same configuration file
6878 and it is reasonable for both to be installed at the same
6879 time, one of these packages must be defined as
6880 <em>owner</em> of the configuration file, i.e., it will be
6881 the package which handles that file as a configuration
6882 file. Other packages that use the configuration file must
6883 depend on the owning package if they require the
6884 configuration file to operate. If the other package will
6885 use the configuration file if present, but is capable of
6886 operating without it, no dependency need be declared.
6890 If it is desirable for two or more related packages to
6891 share a configuration file <em>and</em> for all of the
6892 related packages to be able to modify that configuration
6893 file, then the following should be done:
6894 <enumlist compact="compact">
6896 One of the related packages (the "owning" package)
6897 will manage the configuration file with maintainer
6898 scripts as described in the previous section.
6901 The owning package should also provide a program
6902 that the other packages may use to modify the
6906 The related packages must use the provided program
6907 to make any desired modifications to the
6908 configuration file. They should either depend on
6909 the core package to guarantee that the configuration
6910 modifier program is available or accept gracefully
6911 that they cannot modify the configuration file if it
6912 is not. (This is in addition to the fact that the
6913 configuration file may not even be present in the
6920 Sometimes it's appropriate to create a new package which
6921 provides the basic infrastructure for the other packages
6922 and which manages the shared configuration files. (The
6923 <tt>sgml-base</tt> package is a good example.)
6928 <heading>User configuration files ("dotfiles")</heading>
6931 The files in <file>/etc/skel</file> will automatically be
6932 copied into new user accounts by <prgn>adduser</prgn>.
6933 No other program should reference the files in
6934 <file>/etc/skel</file>.
6938 Therefore, if a program needs a dotfile to exist in
6939 advance in <file>$HOME</file> to work sensibly, that dotfile
6940 should be installed in <file>/etc/skel</file> and treated as a
6945 However, programs that require dotfiles in order to
6946 operate sensibly are a bad thing, unless they do create
6947 the dotfiles themselves automatically.
6951 Furthermore, programs should be configured by the Debian
6952 default installation to behave as closely to the upstream
6953 default behaviour as possible.
6957 Therefore, if a program in a Debian package needs to be
6958 configured in some way in order to operate sensibly, that
6959 should be done using a site-wide configuration file placed
6960 in <file>/etc</file>. Only if the program doesn't support a
6961 site-wide default configuration and the package maintainer
6962 doesn't have time to add it may a default per-user file be
6963 placed in <file>/etc/skel</file>.
6967 <file>/etc/skel</file> should be as empty as we can make it.
6968 This is particularly true because there is no easy (or
6969 necessarily desirable) mechanism for ensuring that the
6970 appropriate dotfiles are copied into the accounts of
6971 existing users when a package is installed.
6977 <heading>Log files</heading>
6979 Log files should usually be named
6980 <file>/var/log/<var>package</var>.log</file>. If you have many
6981 log files, or need a separate directory for permission
6982 reasons (<file>/var/log</file> is writable only by
6983 <file>root</file>), you should usually create a directory named
6984 <file>/var/log/<var>package</var></file> and place your log
6989 Log files must be rotated occasionally so that they don't
6990 grow indefinitely; the best way to do this is to drop a log
6991 rotation configuration file into the directory
6992 <file>/etc/logrotate.d</file> and use the facilities provided by
6993 logrotate.<footnote>
6995 The traditional approach to log files has been to set up
6996 <em>ad hoc</em> log rotation schemes using simple shell
6997 scripts and cron. While this approach is highly
6998 customizable, it requires quite a lot of sysadmin work.
6999 Even though the original Debian system helped a little
7000 by automatically installing a system which can be used
7001 as a template, this was deemed not enough.
7005 The use of <prgn>logrotate</prgn>, a program developed
7006 by Red Hat, is better, as it centralizes log management.
7007 It has both a configuration file
7008 (<file>/etc/logrotate.conf</file>) and a directory where
7009 packages can drop their individual log rotation
7010 configurations (<file>/etc/logrotate.d</file>).
7013 Here is a good example for a logrotate config
7014 file (for more information see <manref name="logrotate"
7016 <example compact="compact">
7017 /var/log/foo/*.log {
7022 /etc/init.d/foo force-reload
7026 This rotates all files under <file>/var/log/foo</file>, saves 12
7027 compressed generations, and forces the daemon to reload its
7028 configuration information after the log rotation.
7032 Log files should be removed when the package is
7033 purged (but not when it is only removed). This should be
7034 done by the <prgn>postrm</prgn> script when it is called
7035 with the argument <tt>purge</tt> (see <ref
7036 id="removedetails">).
7041 <heading>Permissions and owners</heading>
7044 The rules in this section are guidelines for general use.
7045 If necessary you may deviate from the details below.
7046 However, if you do so you must make sure that what is done
7047 is secure and you should try to be as consistent as possible
7048 with the rest of the system. You should probably also
7049 discuss it on <prgn>debian-devel</prgn> first.
7053 Files should be owned by <tt>root.root</tt>, and made
7054 writable only by the owner and universally readable (and
7055 executable, if appropriate), that is mode 644 or 755.
7059 Directories should be mode 755 or (for group-writability)
7060 mode 2775. The ownership of the directory should be
7061 consistent with its mode: if a directory is mode 2775, it
7062 should be owned by the group that needs write access to
7067 Setuid and setgid executables should be mode 4755 or 2755
7068 respectively, and owned by the appropriate user or group.
7069 They should not be made unreadable (modes like 4711 or
7070 2711 or even 4111); doing so achieves no extra security,
7071 because anyone can find the binary in the freely available
7072 Debian package; it is merely inconvenient. For the same
7073 reason you should not restrict read or execute permissions
7074 on non-set-id executables.
7078 Some setuid programs need to be restricted to particular
7079 sets of users, using file permissions. In this case they
7080 should be owned by the uid to which they are set-id, and by
7081 the group which should be allowed to execute them. They
7082 should have mode 4754; again there is no point in making
7083 them unreadable to those users who must not be allowed to
7088 It is possible to arrange that the system administrator can
7089 reconfigure the package to correspond to their local
7090 security policy by changing the permissions on a binary:
7091 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7092 described below.<footnote>
7093 Ordinary files installed by <prgn>dpkg</prgn> (as
7094 opposed to <tt>conffile</tt>s and other similar objects)
7095 normally have their permissions reset to the distributed
7096 permissions when the package is reinstalled. However,
7097 the use of <prgn>dpkg-statoverride</prgn> overrides this
7098 default behaviour. If you use this method, you should
7099 remember to describe <prgn>dpkg-statoverride</prgn> in
7100 the package documentation; being a relatively new
7101 addition to Debian, it is probably not yet well-known.
7103 Another method you should consider is to create a group for
7104 people allowed to use the program(s) and make any setuid
7105 executables executable only by that group.
7109 If you need to create a new user or group for your package
7110 there are two possibilities. Firstly, you may need to
7111 make some files in the binary package be owned by this
7112 user or group, or you may need to compile the user or
7113 group id (rather than just the name) into the binary
7114 (though this latter should be avoided if possible, as in
7115 this case you need a statically allocated id).</p>
7118 If you need a statically allocated id, you must ask for a
7119 user or group id from the <tt>base-passwd</tt> maintainer,
7120 and must not release the package until you have been
7121 allocated one. Once you have been allocated one you must
7122 either make the package depend on a version of the
7123 <tt>base-passwd</tt> package with the id present in
7124 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7125 your package to create the user or group itself with the
7126 correct id (using <tt>adduser</tt>) in its
7127 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7128 the <prgn>postinst</prgn> is to be preferred if it is
7129 possible, otherwise a pre-dependency will be needed on the
7130 <tt>adduser</tt> package.)
7134 On the other hand, the program might be able to determine
7135 the uid or gid from the user or group name at runtime, so
7136 that a dynamically allocated id can be used. In this case
7137 you should choose an appropriate user or group name,
7138 discussing this on <prgn>debian-devel</prgn> and checking
7139 with the <package/base-passwd/ maintainer that it is unique and that
7140 they do not wish you to use a statically allocated id
7141 instead. When this has been checked you must arrange for
7142 your package to create the user or group if necessary using
7143 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7144 <prgn>postinst</prgn> script (again, the latter is to be
7145 preferred if it is possible).
7149 Note that changing the numeric value of an id associated
7150 with a name is very difficult, and involves searching the
7151 file system for all appropriate files. You need to think
7152 carefully whether a static or dynamic id is required, since
7153 changing your mind later will cause problems.
7156 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7158 This section is not intended as policy, but as a
7159 description of the use of <prgn>dpkg-statoverride</prgn>.
7163 <prgn>dpkg-statoverride</prgn> is a replacement for the
7164 deprecated <tt>suidmanager</tt> package. Packages which
7165 previously used <tt>suidmanager</tt> should have a
7166 <tt>Conflicts: suidmanager (<< 0.50)</tt> entry (or even
7167 <tt>(<< 0.52)</tt>), and calls to <tt>suidregister</tt>
7168 and <tt>suidunregister</tt> should now be simply removed
7169 from the maintainer scripts.
7173 If a system administrator wishes to have a file (or
7174 directory or other such thing) installed with owner and
7175 permissions different from those in the distributed Debian
7176 package, he can use the <prgn>dpkg-statoverride</prgn>
7177 program to instruct <prgn>dpkg</prgn> to use the different
7178 settings every time the file is installed. Thus the
7179 package maintainer should distribute the files with their
7180 normal permissions, and leave it for the system
7181 administrator to make any desired changes. For example, a
7182 daemon which is normally required to be setuid root, but
7183 in certain situations could be used without being setuid,
7184 should be installed setuid in the <tt>.deb</tt>. Then the
7185 local system administrator can change this if they wish.
7186 If there are two standard ways of doing it, the package
7187 maintainer can use <tt>debconf</tt> to find out the
7188 preference, and call <prgn>dpkg-statoverride</prgn> in the
7189 maintainer script if necessary to accommodate the system
7190 administrator's choice.
7194 Given the above, <prgn>dpkg-statoverride</prgn> is
7195 essentially a tool for system administrators and would not
7196 normally be needed in the maintainer scripts. There is
7197 one type of situation, though, where calls to
7198 <prgn>dpkg-statoverride</prgn> would be needed in the
7199 maintainer scripts, and that involves packages which use
7200 dynamically allocated user or group ids. In such a
7201 situation, something like the following idiom can be very
7202 helpful in the package's <prgn>postinst</prgn>, where
7203 <tt>sysuser</tt> is a dynamically allocated id:
7205 for i in /usr/bin/foo /usr/sbin/bar
7207 if ! dpkg-statoverride --list $i >/dev/null
7209 dpkg-statoverride --update --add sysuser root 4755 $i
7213 The corresponding <tt>dpkg-statoverride --remove</tt>
7214 calls can then be made unconditionally when the package is
7222 <chapt id="customized-programs">
7223 <heading>Customized programs</heading>
7225 <sect id="arch-spec">
7226 <heading>Architecture specification strings</heading>
7229 If a program needs to specify an <em>architecture specification
7230 string</em> in some place, the following format should be
7231 used: <var>arch</var>-<var>os</var><footnote>
7232 The following architectures and operating systems are
7233 currently recognised by <prgn>dpkg-archictecture</prgn>.
7234 The architecture, <tt><var>arch</var></tt>, is one of
7235 the following: <tt>alpha</tt>, <tt>arm</tt>,
7236 <tt>hppa</tt>, <tt>i386</tt>, <tt>ia64</tt>,
7237 <tt>m68k</tt>, <tt>mips</tt>, <tt>mipsel</tt>,
7238 <tt>powerpc</tt>, <tt>s390</tt>, <tt>sh</tt>,
7239 <tt>sheb</tt>, <tt>sparc</tt> and <tt>sparc64</tt>. The
7240 operating system, <tt><var>os</var></tt>, is one of:
7241 <tt>linux</tt>, <tt>gnu</tt>, <tt>freebsd</tt> and
7242 <tt>openbsd</tt>. Use of <tt>gnu</tt> in this string is
7243 reserved for the GNU/Hurd operating system.
7248 Note that we don't want to use
7249 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7250 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7251 since this would make our programs incompatible with other
7252 Linux distributions. We also don't use something like
7253 <tt><var>arch</var>-unknown-linux</tt>, since the
7254 <tt>unknown</tt> does not look very good.
7259 <heading>Daemons</heading>
7262 The configuration files <file>/etc/services</file>,
7263 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7264 by the <prgn>netbase</prgn> package and must not be modified
7269 If a package requires a new entry in one of these files, the
7270 maintainer should get in contact with the
7271 <prgn>netbase</prgn> maintainer, who will add the entries
7272 and release a new version of the <prgn>netbase</prgn>
7277 The configuration file <file>/etc/inetd.conf</file> must not be
7278 modified by the package's scripts except via the
7279 <prgn>update-inetd</prgn> script or the
7280 <file>DebianNet.pm</file> Perl module. See their documentation
7281 for details on how to add entries.
7285 If a package wants to install an example entry into
7286 <file>/etc/inetd.conf</file>, the entry must be preceded with
7287 exactly one hash character (<tt>#</tt>). Such lines are
7288 treated as "commented out by user" by the
7289 <prgn>update-inetd</prgn> script and are not changed or
7290 activated during package updates.
7295 <heading>Using pseudo-ttys and modifying wtmp, utmp and
7299 Some programs need to create pseudo-ttys. This should be done
7300 using Unix98 ptys if the C library supports it. The resulting
7301 program must not be installed setuid root, unless that
7302 is required for other functionality.
7306 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
7307 <file>/var/log/lastlog</file> must be installed writeable by
7308 group <tt>utmp</tt>. Programs which need to modify those
7309 files must be installed setgid <tt>utmp</tt>.
7314 <heading>Editors and pagers</heading>
7317 Some programs have the ability to launch an editor or pager
7318 program to edit or display a text document. Since there are
7319 lots of different editors and pagers available in the Debian
7320 distribution, the system administrator and each user should
7321 have the possibility to choose his/her preferred editor and
7326 In addition, every program should choose a good default
7327 editor/pager if none is selected by the user or system
7332 Thus, every program that launches an editor or pager must
7333 use the EDITOR or PAGER environment variable to determine
7334 the editor or pager the user wishes to use. If these
7335 variables are not set, the programs <file>/usr/bin/editor</file>
7336 and <file>/usr/bin/pager</file> should be used, respectively.
7340 These two files are managed through the <prgn>dpkg</prgn>
7341 "alternatives" mechanism. Thus every package providing an
7342 editor or pager must call the
7343 <prgn>update-alternatives</prgn> script to register these
7348 If it is very hard to adapt a program to make use of the
7349 EDITOR or PAGER variables, that program may be configured to
7350 use <file>/usr/bin/sensible-editor</file> and
7351 <file>/usr/bin/sensible-pager</file> as the editor or pager
7352 program respectively. These are two scripts provided in the
7353 Debian base system that check the EDITOR and PAGER variables
7354 and launch the appropriate program, and fall back to
7355 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
7356 variable is not set.
7360 A program may also use the VISUAL environment variable to
7361 determine the user's choice of editor. If it exists, it
7362 should take precedence over EDITOR. This is in fact what
7363 <file>/usr/bin/sensible-editor</file> does.
7367 It is not required for a package to depend on
7368 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
7369 package to provide such virtual packages.<footnote>
7370 The Debian base system already provides an editor and a
7376 <sect id="web-appl">
7377 <heading>Web servers and applications</heading>
7380 This section describes the locations and URLs that should
7381 be used by all web servers and web applications in the
7388 Cgi-bin executable files are installed in the
7390 <example compact="compact">
7391 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
7393 and should be referred to as
7394 <example compact="compact">
7395 http://localhost/cgi-bin/<var>cgi-bin-name</var>
7400 <p>Access to HTML documents</p>
7403 HTML documents for a package are stored in
7404 <file>/usr/share/doc/<var>package</var></file>
7405 and can be referred to as
7406 <example compact="compact">
7407 http://localhost/doc/<var>package</var>/<var>filename</var>
7412 The web server should restrict access to the document
7413 tree so that only clients on the same host can read
7414 the documents. If the web server does not support such
7415 access controls, then it should not provide access at
7416 all, or ask about providing access during installation.
7421 <p>Web Document Root</p>
7424 Web Applications should try to avoid storing files in
7425 the Web Document Root. Instead they should use the
7426 /usr/share/doc/<var>package</var> directory for
7427 documents and register the Web Application via the
7428 menu package. If access to the web document root is
7429 unavoidable then use
7430 <example compact="compact">
7433 as the Document Root. This might be just a symbolic
7434 link to the location where the system administrator
7435 has put the real document root.
7443 <sect id="mail-transport-agents">
7444 <heading>Mail transport, delivery and user agents</heading>
7447 Debian packages which process electronic mail, whether mail
7448 user agents (MUAs) or mail transport agents (MTAs), must
7449 ensure that they are compatible with the configuration
7450 decisions below. Failure to do this may result in lost
7451 mail, broken <tt>From:</tt> lines, and other serious brain
7456 The mail spool is <file>/var/mail</file> and the interface to
7457 send a mail message is <file>/usr/sbin/sendmail</file> (as per
7458 the FHS). On older systems, the mail spool may be
7459 physically located in <file>/var/spool/mail</file>, but all
7460 access to the mail spool should be via the
7461 <file>/var/mail</file> symlink. The mail spool is part of the
7462 base system and not part of the MTA package.
7466 All Debian MUAs, MTAs, MDAs and other mailbox accessing
7467 programs (such as IMAP daemons) must lock the mailbox in an
7468 NFS-safe way. This means that <tt>fcntl()</tt> locking must
7469 be combined with dot locking. To avoid deadlocks, a program
7470 should use <tt>fcntl()</tt> first and dot locking after
7471 this, or alternatively implement the two locking methods in
7472 a non blocking way<footnote>
7473 If it is not possible to establish both locks, the
7474 system shouldn't wait for the second lock to be
7475 established, but remove the first lock, wait a (random)
7476 time, and start over locking again.
7477 </footnote>. Using the functions <tt>maillock</tt> and
7478 <tt>mailunlock</tt> provided by the
7479 <tt>liblockfile*</tt><footnote>
7480 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
7481 to use these functions.
7482 </footnote> packages is the recommended way to realize this.
7486 Mailboxes are generally mode 660
7487 <tt><var>user</var>.mail</tt> unless the system
7488 administrator has chosen otherwise. A MUA may remove a
7489 mailbox (unless it has nonstandard permissions) in which
7490 case the MTA or another MUA must recreate it if needed.
7491 Mailboxes must be writable by group mail.
7495 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
7496 be setgid mail to do the locking mentioned above (and
7497 must obviously avoid accessing other users' mailboxes
7498 using this privilege).</p>
7501 <file>/etc/aliases</file> is the source file for the system mail
7502 aliases (e.g., postmaster, usenet, etc.), it is the one
7503 which the sysadmin and <prgn>postinst</prgn> scripts may
7504 edit. After <file>/etc/aliases</file> is edited the program or
7505 human editing it must call <prgn>newaliases</prgn>. All MTA
7506 packages must come with a <prgn>newaliases</prgn> program,
7507 even if it does nothing, but older MTA packages did not do
7508 this so programs should not fail if <prgn>newaliases</prgn>
7509 cannot be found. Note that because of this, all MTA
7510 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
7511 <tt>Replaces: mail-transport-agent</tt> control file
7516 The convention of writing <tt>forward to
7517 <var>address</var></tt> in the mailbox itself is not
7518 supported. Use a <tt>.forward</tt> file instead.</p>
7521 The <prgn>rmail</prgn> program used by UUCP
7522 for incoming mail should be <file>/usr/sbin/rmail</file>.
7523 Likewise, <prgn>rsmtp</prgn>, for receiving
7524 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
7528 If your package needs to know what hostname to use on (for
7529 example) outgoing news and mail messages which are generated
7530 locally, you should use the file <file>/etc/mailname</file>. It
7531 will contain the portion after the username and <tt>@</tt>
7532 (at) sign for email addresses of users on the machine
7533 (followed by a newline).
7537 Such package should check for the existence of this file
7538 when it is being configured. If it exists, it should be
7539 used without comment, although an MTA's configuration script
7540 may wish to prompt the user even if it finds that this file
7541 exists. If the file does not exist, the package should
7542 prompt the user for the value (preferably using
7543 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
7544 as well as using it in the package's configuration. The
7545 prompt should make it clear that the name will not just be
7546 used by that package. For example, in this situation the
7547 <tt>inn</tt> package could say something like:
7548 <example compact="compact">
7549 Please enter the "mail name" of your system. This is the
7550 hostname portion of the address to be shown on outgoing
7551 news and mail messages. The default is
7552 <var>syshostname</var>, your system's host name. Mail
7553 name ["<var>syshostname</var>"]:
7555 where <var>syshostname</var> is the output of <tt>hostname
7561 <heading>News system configuration</heading>
7564 All the configuration files related to the NNTP (news)
7565 servers and clients should be located under
7566 <file>/etc/news</file>.</p>
7569 There are some configuration issues that apply to a number
7570 of news clients and server packages on the machine. These
7574 <tag><file>/etc/news/organization</file></tag>
7576 A string which should appear as the
7577 organization header for all messages posted
7578 by NNTP clients on the machine
7581 <tag><file>/etc/news/server</file></tag>
7583 Contains the FQDN of the upstream NNTP
7584 server, or localhost if the local machine is
7589 Other global files may be added as required for cross-package news
7596 <heading>Programs for the X Window System</heading>
7599 <heading>Providing X support and package priorities</heading>
7602 Programs that can be configured with support for the X
7603 Window System must be configured to do so and must declare
7604 any package dependencies necessary to satisfy their
7605 runtime requirements when using the X Window System. If
7606 such a package is of higher priority than the X packages
7607 on which it depends, it is required that either the
7608 X-specific components be split into a separate package, or
7609 that an alternative version of the package, which includes
7610 X support, be provided, or that the package's priority be
7616 <heading>Packages providing an X server</heading>
7619 Packages that provide an X server that, directly or
7620 indirectly, communicates with real input and display
7621 hardware should declare in their control data that they
7622 provide the virtual package <tt>xserver</tt>.<footnote>
7623 This implements current practice, and provides an
7624 actual policy for usage of the <tt>xserver</tt>
7625 virtual package which appears in the virtual packages
7626 list. In a nutshell, X servers that interface
7627 directly with the display and input hardware or via
7628 another subsystem (e.g., GGI) should provide
7629 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
7630 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
7636 <heading>Packages providing a terminal emulator</heading>
7639 Packages that provide a terminal emulator for the X Window
7640 System which meet the criteria listed below should declare
7641 in their control data that they provide the virtual
7642 package <tt>x-terminal-emulator</tt>. They should also
7643 register themselves as an alternative for
7644 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
7649 To be an <tt>x-terminal-emulator</tt>, a program must:
7650 <list compact="compact">
7652 Be able to emulate a DEC VT100 terminal, or a
7653 compatible terminal.
7657 Support the command-line option <tt>-e
7658 <var>command</var></tt>, which creates a new
7659 terminal window<footnote>
7660 "New terminal window" does not necessarily mean
7661 a new top-level X window directly parented by
7662 the window manager; it could, if the terminal
7663 emulator application were so coded, be a new
7664 "view" in a multiple-document interface (MDI).
7666 and runs the specified <var>command</var>,
7667 interpreting the entirity of the rest of the command
7668 line as a command to pass straight to exec, in the
7669 manner that <tt>xterm</tt> does.
7673 Support the command-line option <tt>-T
7674 <var>title</var></tt>, which creates a new terminal
7675 window with the window title <var>title</var>.
7682 <heading>Packages providing a window manager</heading>
7685 Packages that provide a window manager should declare in
7686 their control data that they provide the virtual package
7687 <tt>x-window-manager</tt>. They should also register
7688 themselves as an alternative for
7689 <file>/usr/bin/x-window-manager</file>, with a priority
7690 calculated as follows:
7691 <list compact="compact">
7693 Start with a priority of 20.
7697 If the window manager supports the Debian menu
7698 system, add 20 points if this support is available
7699 in the package's default configuration (i.e., no
7700 configuration files belonging to the system or user
7701 have to be edited to activate the feature); if
7702 configuration files must be modified, add only 10
7708 If the window manager complies with <url
7709 id="http://www.freedesktop.org/standards/wm-spec.html"
7710 name="The Window Manager Specification Project">,
7711 written by the <url id="http://www.freedesktop.org/"
7712 name="Free Desktop Group">, add 40 points.
7716 If the window manager permits the X session to be
7717 restarted using a <em>different</em> window manager
7718 (without killing the X server) in its default
7719 configuration, add 10 points; otherwise add none.
7726 <heading>Packages providing fonts</heading>
7729 Packages that provide fonts for the X Window
7731 For the purposes of Debian Policy, a "font for the X
7732 Window System" is one which is accessed via X protocol
7733 requests. Fonts for the Linux console, for PostScript
7734 renderers, or any other purpose, do not fit this
7735 definition. Any tool which makes such fonts available
7736 to the X Window System, however, must abide by this
7739 must do a number of things to ensure that they are both
7740 available without modification of the X or font server
7741 configuration, and that they do not corrupt files used by
7742 other font packages to register information about
7746 Fonts of any type supported by the X Window System
7747 must be in a separate binary package from any
7748 executables, libraries, or documentation (except
7749 that specific to the fonts shipped, such as their
7750 license information). If one or more of the fonts
7751 so packaged are necessary for proper operation of
7752 the package with which they are associated the font
7753 package may be Recommended; if the fonts merely
7754 provide an enhancement, a Suggests relationship may
7755 be used. Packages must not Depend on font
7757 This is because the X server may retrieve fonts
7758 from the local filesystem or over the network
7759 from an X font server; the Debian package system
7760 is empowered to deal only with the local
7766 BDF fonts must be converted to PCF fonts with the
7767 <prgn>bdftopcf</prgn> utility (available in the
7768 <tt>xutils</tt> package, <prgn>gzip</prgn>ped, and
7769 placed in a directory that corresponds to their
7771 <list compact="compact">
7773 100 dpi fonts must be placed in
7774 <file>/usr/X11R6/lib/X11/fonts/100dpi/</file>.
7778 75 dpi fonts must be placed in
7779 <file>/usr/X11R6/lib/X11/fonts/75dpi/</file>.
7783 Character-cell fonts, cursor fonts, and other
7784 low-resolution fonts must be placed in
7785 <file>/usr/X11R6/lib/X11/fonts/misc/</file>.
7791 Speedo fonts must be placed in
7792 <file>/usr/X11R6/lib/X11/fonts/Speedo/</file>.
7796 Type 1 fonts must be placed in
7797 <file>/usr/X11R6/lib/X11/fonts/Type1/</file>. If font
7798 metric files are available, they must be placed here
7803 Subdirectories of <file>/usr/X11R6/lib/X11/fonts/</file>
7804 other than those listed above must be neither
7805 created nor used. (The <file>PEX</file>, <file>CID</file>,
7806 and <file>cyrillic</file> directories are excepted for
7807 historical reasons, but installation of files into
7808 these directories remains discouraged.)
7812 Font packages may, instead of placing files directly
7813 in the X font directories listed above, provide
7814 symbolic links in that font directory pointing to
7815 the files' actual location in the filesystem. Such
7816 a location must comply with the FHS.
7820 Font packages should not contain both 75dpi and
7821 100dpi versions of a font. If both are available,
7822 they should be provided in separate binary packages
7823 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
7824 the names of the packages containing the
7825 corresponding fonts.
7829 Fonts destined for the <file>misc</file> subdirectory
7830 should not be included in the same package as 75dpi
7831 or 100dpi fonts; instead, they should be provided in
7832 a separate package with <tt>-misc</tt> appended to
7837 Font packages must not provide the files
7838 <file>fonts.dir</file>, <file>fonts.alias</file>, or
7839 <file>fonts.scale</file> in a font directory:
7842 <file>fonts.dir</file> files must not be provided at all.
7846 <file>fonts.alias</file> and <file>fonts.scale</file>
7847 files, if needed, should be provided in the
7849 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
7850 where <var>fontdir</var> is the name of the
7852 <file>/usr/X11R6/lib/X11/fonts/</file> where the
7853 package's corresponding fonts are stored
7854 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
7855 <var>package</var> is the name of the package
7856 that provides these fonts, and
7857 <var>extension</var> is either <tt>scale</tt>
7858 or <tt>alias</tt>, whichever corresponds to
7865 Font packages must declare a dependency on
7866 <tt>xutils (>> 4.0.3)</tt> in their control
7871 Font packages that provide one or more
7872 <file>fonts.scale</file> files as described above must
7873 invoke <prgn>update-fonts-scale</prgn> on each
7874 directory into which they installed fonts
7875 <em>before</em> invoking
7876 <prgn>update-fonts-dir</prgn> on that directory.
7877 This invocation must occur in both the
7878 <prgn>postinst</prgn> (for all arguments) and
7879 <prgn>postrm</prgn> (for all arguments except
7880 <tt>upgrade</tt>) scripts.
7884 Font packages that provide one or more
7885 <file>fonts.alias</file> files as described above must
7886 invoke <prgn>update-fonts-alias</prgn> on each
7887 directory into which they installed fonts. This
7888 invocation must occur in both the
7889 <prgn>postinst</prgn> (for all arguments) and
7890 <prgn>postrm</prgn> (for all arguments except
7891 <tt>upgrade</tt>) scripts.
7895 Font packages must invoke
7896 <prgn>update-fonts-dir</prgn> on each directory into
7897 which they installed fonts. This invocation must
7898 occur in both the <prgn>postinst</prgn> (for all
7899 arguments) and <prgn>postrm</prgn> (for all
7900 arguments except <tt>upgrade</tt>) scripts.
7904 Font packages must not provide alias names for the
7905 fonts they include which collide with alias names
7906 already in use by fonts already packaged.
7910 Font packages must not provide fonts with the same
7911 XLFD registry name as another font already packaged.
7918 <heading>Application defaults files</heading>
7921 Application defaults files must be installed in the
7922 directory <file>/etc/X11/app-defaults/</file> (use of a
7923 localized subdirectory of <file>/etc/X11/</file> as described
7924 in the <em>X Toolkit Intrinsics - C Language
7925 Interface</em> manual is also permitted). They must be
7926 registered as <tt>conffile</tt>s or handled as
7927 configuration files. Packages must not provide the
7928 directory <file>/usr/X11R6/lib/X11/app-defaults/</file>.
7932 Customization of programs' X resources may also be
7933 supported with the provision of a file with the same name
7934 as that of the package placed in the
7935 <file>/etc/X11/Xresources/</file> directory, which must
7936 registered as a <tt>conffile</tt> or handled as a
7937 configuration file.<footnote>
7938 Note that this mechanism is not the same as using
7939 app-defaults; app-defaults are tied to the client
7940 binary on the local filesystem, whereas X resources
7941 are stored in the X server and affect all connecting
7944 <em>Important:</em> packages that install files into the
7945 <file>/etc/X11/Xresources/</file> directory must conflict with
7946 <tt>xbase (<< 3.3.2.3a-2)</tt>; if this is not done
7947 it is possible for the installing package to destroy a
7948 previously-existing <file>/etc/X11/Xresources</file> file
7949 which had been customized by the system administrator.
7954 <heading>Installation directory issues</heading>
7957 Packages using the X Window System should not be
7958 configured to install files under the <file>/usr/X11R6/</file>
7959 directory unless they use <prgn>imake</prgn>. The
7960 <file>/usr/X11R6/</file> directory hierarchy should be
7961 regarded as deprecated for all packages except the X
7962 Window System itself, and those which use the
7963 <prgn>imake</prgn> program it provides, in which case the
7964 packages may transition out of the <file>/usr/X11R6/</file>
7965 directory at the maintainer's discretion.<footnote>
7966 <prgn>Imake</prgn>-using programs are exempt because,
7967 as long as they are written correctly, the pathnames
7968 they use to locate resources and install themselves
7969 are derived wholly from the X Window System
7970 configuration. Thus, in the event that the X Window
7971 System moves to <file>/usr/X11R7/</file>,
7972 <file>/usr/X12/</file>, or just plain <file>/usr/</file>, all
7973 that is required for these programs is a recompile
7974 against the corresponding X Window System library
7975 development packages.
7980 Programs that use GNU <prgn>autoconf</prgn> and
7981 <prgn>automake</prgn> are usually easily configured at
7982 compile time to use <file>/usr/</file> instead of
7983 <file>/usr/X11R6/</file>, and this should be done whenever
7984 possible. Configuration files for window managers and
7985 display managers should be placed in a subdirectory of
7986 <file>/etc/X11/</file> corresponding to the package name due
7987 to these programs' tight integration with the mechanisms
7988 of the X Window System. Application-level programs should
7989 use the <file>/etc/</file> directory unless otherwise mandated
7994 The installation of files into subdirectories
7995 of <file>/usr/X11R6/include/X11/</file> and
7996 <file>/usr/X11R6/lib/X11/</file> is permitted but discouraged;
7997 package maintainers should determine if subdirectories of
7998 <file>/usr/lib/</file> and <file>/usr/share/</file> can be used
7999 instead. (The use of symbolic links from the
8000 <file>X11R6</file> directories to other FHS-compliant
8001 locations is encouraged if the program is not easily
8002 configured to look elsewhere for its files.)
8006 Packages must not provide or install files into the directories
8007 <file>/usr/bin/X11/</file>, <file>/usr/include/X11/</file> or
8008 <file>/usr/lib/X11/</file>. Files within a package should,
8009 however, make reference to these directories, rather than
8010 their <tt>X11R6</tt>-named counterparts
8011 <file>/usr/X11R6/bin/</file>, <file>/usr/X11R6/include/X11/</file>
8012 and <file>/usr/X11R6/lib/X11/</file>, if the resources being
8013 referred to have not been moved to other FHS-compliant
8019 <heading>The OSF/Motif and OpenMotif libraries</heading>
8022 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8023 OpenMotif libraries</em><footnote>
8024 OSF/Motif and OpenMotif are collectively referred to as
8025 "Motif" in this policy document.
8027 should be compiled against and tested with LessTif (a free
8028 re-implementation of Motif) instead. If the maintainer
8029 judges that the program or programs do not work
8030 sufficiently well with LessTif to be distributed and
8031 supported, but do so when compiled against Motif, then two
8032 versions of the package should be created; one linked
8033 statically against Motif and with <tt>-smotif</tt>
8034 appended to the package name, and one linked dynamically
8035 against Motif and with <tt>-dmotif</tt> appended to the
8040 Both Motif-linked versions are dependent
8041 upon non-DFSG-compliant software and thus cannot be
8042 uploaded to the <em>main</em> distribution; if the
8043 software is itself DFSG-compliant it may be uploaded to
8044 the <em>contrib</em> distribution. While known existing
8045 versions of Motif permit unlimited redistribution of
8046 binaries linked against the library (whether statically or
8047 dynamically), it is the package maintainer's
8048 responsibility to determine whether this is permitted by
8049 the license of the copy of Motif in his or her possession.
8055 <heading>Perl programs and modules</heading>
8058 Perl programs and modules should follow the current Perl policy.
8062 The Perl policy can be found in the <tt>perl-policy</tt>
8063 files in the <tt>debian-policy</tt> package.
8064 It is also available from the Debian web mirrors at
8065 <tt><url name="/doc/packaging-manuals/perl-policy/"
8066 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>
8067 and from the Debian archive mirrors at
8068 <tt><url name="/doc/package-developer/perl-policy.txt.gz"
8069 id="http://ftp.debian.org/debian/doc/package-developer/perl-policy.txt.gz"></tt>.
8074 <heading>Emacs lisp programs</heading>
8077 Please refer to the "Debian Emacs Policy" for details of how to
8078 package emacs lisp programs.
8082 The Emacs policy is available in
8083 <file>debian-emacs-policy.gz</file> of the
8084 <package>emacsen-common</package> package.
8085 It is also available from the Debian web mirrors at
8086 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8087 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8092 <heading>Games</heading>
8095 The permissions on <file>/var/games</file> are mode 755, owner
8096 <tt>root</tt> and group <tt>root</tt>.
8100 Each game decides on its own security policy.</p>
8103 Games which require protected, privileged access to
8104 high-score files, savegames, etc., may be made
8105 set-<em>group</em>-id (mode 2755) and owned by
8106 <tt>root.games</tt>, and use files and directories with
8107 appropriate permissions (770 <tt>root.games</tt>, for
8108 example). They must not be made
8109 set-<em>user</em>-id, as this causes security problems. (If
8110 an attacker can subvert any set-user-id game they can
8111 overwrite the executable of any other, causing other players
8112 of these games to run a Trojan horse program. With a
8113 set-group-id game the attacker only gets access to less
8114 important game data, and if they can get at the other
8115 players' accounts at all it will take considerably more
8119 Some packages, for example some fortune cookie programs, are
8120 configured by the upstream authors to install with their
8121 data files or other static information made unreadable so
8122 that they can only be accessed through set-id programs
8123 provided. You should not do this in a Debian package: anyone can
8124 download the <file>.deb</file> file and read the data from it,
8125 so there is no point making the files unreadable. Not
8126 making the files unreadable also means that you don't have
8127 to make so many programs set-id, which reduces the risk of a
8131 As described in the FHS, binaries of games should be
8132 installed in the directory <file>/usr/games</file>. This also
8133 applies to games that use the X Window System. Manual pages
8134 for games (X and non-X games) should be installed in
8135 <file>/usr/share/man/man6</file>.</p>
8141 <heading>Documentation</heading>
8144 <heading>Manual pages</heading>
8147 You should install manual pages in <prgn>nroff</prgn> source
8148 form, in appropriate places under <file>/usr/share/man</file>.
8149 You should only use sections 1 to 9 (see the FHS for more
8150 details). You must not install a preformatted "cat page".
8154 Each program, utility, and function should have an
8155 associated manual page included in the same package. It is
8156 suggested that all configuration files also have a manual
8157 page included as well. Manual pages for protocols and other
8158 auxiliary things are optional.
8162 If no manual page is available, this is considered as a bug
8163 and should be reported to the Debian Bug Tracking System (the
8164 maintainer of the package is allowed to write this bug report
8165 themselves, if they so desire). Do not close the bug report
8166 until a proper manpage is available.<footnote>
8167 It is not very hard to write a man page. See the
8168 <url id="http://www.schweikhardt.net/man_page_howto.html"
8169 name="Man-Page-HOWTO">,
8170 <manref name="man" section="7">, the examples
8171 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8172 the helper programs <prgn>help2man</prgn>, or the
8173 directory <file>/usr/share/doc/man-db/examples</file>.
8178 You may forward a complaint about a missing manpage to the
8179 upstream authors, and mark the bug as forwarded in the
8180 Debian bug tracking system. Even though the GNU Project do
8181 not in general consider the lack of a manpage to be a bug,
8182 we do; if they tell you that they don't consider it a bug
8183 you should leave the bug in our bug tracking system open
8188 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8192 If one manpage needs to be accessible via several names it
8193 is better to use a symbolic link than the <file>.so</file>
8194 feature, but there is no need to fiddle with the relevant
8195 parts of the upstream source to change from <file>.so</file> to
8196 symlinks: don't do it unless it's easy. You should not
8197 create hard links in the manual page directories, nor put
8198 absolute filenames in <file>.so</file> directives. The filename
8199 in a <file>.so</file> in a manpage should be relative to the
8200 base of the manpage tree (usually
8201 <file>/usr/share/man</file>). If you do not create any links
8202 (whether symlinks, hard links, or <tt>.so</tt> directives)
8203 in the filesystem to the alternate names of the manpage,
8204 then you should not rely on <prgn>man</prgn> finding your
8205 manpage under those names based solely on the information in
8206 the manpage's header.<footnote>
8207 Supporting this in <prgn>man</prgn> often requires
8208 unreasonable processing time to find a manual page or to
8209 report that none exists, and moves knowledge into man's
8210 database that would be better left in the filesystem.
8211 This support is therefore deprecated and will cease to
8212 be present in the future.
8218 <heading>Info documents</heading>
8221 Info documents should be installed in <file>/usr/share/info</file>.
8222 They should be compressed with <tt>gzip -9</tt>.
8226 Your package should call <prgn>install-info</prgn> to update
8227 the Info <file>dir</file> file in its <prgn>postinst</prgn>
8228 script when called with a <tt>configure</tt> argument, for
8230 <example compact="compact">
8231 install-info --quiet --section Development Development \
8232 /usr/share/info/foobar.info
8236 It is a good idea to specify a section for the location of
8237 your program; this is done with the <tt>--section</tt>
8238 switch. To determine which section to use, you should look
8239 at <file>/usr/share/info/dir</file> on your system and choose the most
8240 relevant (or create a new section if none of the current
8241 sections are relevant). Note that the <tt>--section</tt>
8242 flag takes two arguments; the first is a regular expression
8243 to match (case-insensitively) against an existing section,
8244 the second is used when creating a new one.</p>
8247 You should remove the entries in the <prgn>prerm</prgn>
8248 script when called with a <tt>remove</tt> argument:
8249 <example compact="compact">
8250 install-info --quiet --remove /usr/share/info/foobar.info
8254 If <prgn>install-info</prgn> cannot find a description entry
8255 in the Info file you must supply one. See <manref
8256 name="install-info" section="8"> for details.</p>
8260 <heading>Additional documentation</heading>
8263 Any additional documentation that comes with the package may
8264 be installed at the discretion of the package maintainer.
8265 Text documentation should be installed in the directory
8266 <file>/usr/share/doc/<var>package</var></file>, where
8267 <var>package</var> is the name of the package, and
8268 compressed with <tt>gzip -9</tt> unless it is small.
8272 If a package comes with large amounts of documentation which
8273 many users of the package will not require you should create
8274 a separate binary package to contain it, so that it does not
8275 take up disk space on the machines of users who do not need
8276 or want it installed.</p>
8279 It is often a good idea to put text information files
8280 (<file>README</file>s, changelogs, and so forth) that come with
8281 the source package in <file>/usr/share/doc/<var>package</var></file>
8282 in the binary package. However, you don't need to install
8283 the instructions for building and installing the package, of
8287 Packages must not require the existence of any files in
8288 <file>/usr/share/doc/</file> in order to function
8290 The system administrator should be able to
8291 delete files in <file>/usr/share/doc/</file> without causing
8292 any programs to break.
8294 Any files that are referenced by programs but are also
8295 useful as standalone documentation should be installed under
8296 <file>/usr/share/<var>package</var>/</file> with symbolic links from
8297 <file>/usr/share/doc/<var>package</var></file>.
8301 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8302 link to another directory in <file>/usr/share/doc</file> only if
8303 the two packages both come from the same source and the
8304 first package Depends on the second.
8308 Former Debian releases placed all additional documentation
8309 in <file>/usr/doc/<var>package</var></file>. This has been
8310 changed to <file>/usr/share/doc/<var>package</var></file>,
8311 and packages must not put documentation in the directory
8312 <file>/usr/doc/<var>package</var></file>. <footnote>
8313 At this phase of the transition, we no longer require a
8314 symbolic link in <file>/usr/doc/</file>. At a later point,
8315 policy shall change to make the symbolic links a bug.
8321 <heading>Preferred documentation formats</heading>
8324 The unification of Debian documentation is being carried out
8328 If your package comes with extensive documentation in a
8329 markup format that can be converted to various other formats
8330 you should if possible ship HTML versions in a binary
8331 package, in the directory
8332 <file>/usr/share/doc/<var>appropriate-package</var></file> or
8333 its subdirectories.<footnote>
8334 The rationale: The important thing here is that HTML
8335 docs should be available in <em>some</em> package, not
8336 necessarily in the main binary package.
8341 Other formats such as PostScript may be provided at the
8342 package maintainer's discretion.
8346 <sect id="copyrightfile">
8347 <heading>Copyright information</heading>
8350 Every package must be accompanied by a verbatim copy of its
8351 copyright and distribution license in the file
8352 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
8353 file must neither be compressed nor be a symbolic link.
8357 In addition, the copyright file must say where the upstream
8358 sources (if any) were obtained. It should name the original
8359 authors of the package and the Debian maintainer(s) who were
8360 involved with its creation.</p>
8363 A copy of the file which will be installed in
8364 <file>/usr/share/doc/<var>package</var>/copyright</file> should
8365 be in <file>debian/copyright</file> in the source package.
8369 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8370 link to another directory in <file>/usr/share/doc</file> only if
8371 the two packages both come from the same source and the
8372 first package Depends on the second. These rules are
8373 important because copyrights must be extractable by
8378 Packages distributed under the UCB BSD license, the Artistic
8379 license, the GNU GPL, and the GNU LGPL should refer to the
8380 files <file>/usr/share/common-licenses/BSD</file>,
8381 <file>/usr/share/common-licenses/Artistic</file>,
8382 <file>/usr/share/common-licenses/GPL</file>, and
8383 <file>/usr/share/common-licenses/LGPL</file> respectively,
8384 rather than quoting them in the copyright file.
8388 You should not use the copyright file as a general <file>README</file>
8389 file. If your package has such a file it should be
8390 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
8391 <file>README.Debian</file> or some other appropriate place.</p>
8395 <heading>Examples</heading>
8398 Any examples (configurations, source files, whatever),
8399 should be installed in a directory
8400 <file>/usr/share/doc/<var>package</var>/examples</file>. These
8401 files should not be referenced by any program: they're there
8402 for the benefit of the system administrator and users as
8403 documentation only. Architecture-specific example files
8404 should be installed in a directory
8405 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
8407 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
8408 latter directory itself may be a symbolic link to the
8413 If the purpose of a package is to provide examples, then the
8414 example files may be installed into
8415 <file>/usr/share/doc/<var>package</var></file>.
8419 <sect id="changelogs">
8420 <heading>Changelog files</heading>
8423 Packages that are not Debian-native must contain a
8424 compressed copy of the <file>debian/changelog</file> file from
8425 the Debian source tree in
8426 <file>/usr/share/doc/<var>package</var></file> with the name
8427 <file>changelog.Debian.gz</file>.
8431 If an upstream changelog is available, it should be accessible as
8432 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
8433 plain text. If the upstream changelog is distributed in
8434 HTML, it should be made available in that form as
8435 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
8436 and a plain text <file>changelog.gz</file> should be generated
8437 from it using, for example, <tt>lynx -dump -nolist</tt>. If
8438 the upstream changelog files do not already conform to this
8439 naming convention, then this may be achieved either by
8440 renaming the files, or by adding a symbolic link, at the
8441 maintainer's discretion.<footnote>
8442 Rationale: People should not have to look in places for
8443 upstream changelogs merely because they are given
8444 different names or are distributed in HTML format.
8449 All of these files should be installed compressed using
8450 <tt>gzip -9</tt>, as they will become large with time even
8451 if they start out small.
8455 If the package has only one changelog which is used both as
8456 the Debian changelog and the upstream one because there is
8457 no separate upstream maintainer then that changelog should
8458 usually be installed as
8459 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
8460 there is a separate upstream maintainer, but no upstream
8461 changelog, then the Debian changelog should still be called
8462 <file>changelog.Debian.gz</file>.
8466 For details about the format and contents of the Debian
8467 changelog file, please see <ref id="dpkgchangelog">.
8472 <appendix id="pkg-scope">
8473 <heading>Introduction and scope of these appendices</heading>
8476 These appendices are taken essentially verbatim from the
8477 now-deprecated Packaging Manual, version 3.2.1.0. They are
8478 the chapters which are likely to be of use to package
8479 maintainers and which have not already been included in the
8480 policy document itself. Most of these sections are very likely
8481 not relevant to policy; they should be treated as
8482 documentation for the packaging system. Please note that these
8483 appendices are included for convenience, and for historical
8484 reasons: they used to be part of policy package, and they have
8485 not yet been incorporated into dpkg documentation. However,
8486 they still have value, and hence they are presented here.
8490 They have not yet been checked to ensure that they are
8491 compatible with the contents of policy, and if there are any
8492 contradictions, the version in the main policy document takes
8493 precedence. The remaining chapters of the old Packaging
8494 Manual have also not been read in detail to ensure that there
8495 are not parts which have been left out. Both of these will be
8500 Certain parts of the Packaging manual were integrated into the
8501 Policy Manual proper, and removed from the appendices. Links
8502 have been placed from the old locations to the new ones.
8506 <prgn>dpkg</prgn> is a suite of programs for creating binary
8507 package files and installing and removing them on Unix
8509 <prgn>dpkg</prgn> is targetted primarily at Debian
8510 GNU/Linux, but may work on or be ported to other
8516 The binary packages are designed for the management of
8517 installed executable programs (usually compiled binaries) and
8518 their associated data, though source code examples and
8519 documentation are provided as part of some packages.</p>
8522 This manual describes the technical aspects of creating Debian
8523 binary packages (<file>.deb</file> files). It documents the
8524 behaviour of the package management programs
8525 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
8526 they interact with packages.</p>
8529 It also documents the interaction between
8530 <prgn>dselect</prgn>'s core and the access method scripts it
8531 uses to actually install the selected packages, and describes
8532 how to create a new access method.</p>
8535 This manual does not go into detail about the options and
8536 usage of the package building and installation tools. It
8537 should therefore be read in conjuction with those programs'
8542 The utility programs which are provided with <prgn>dpkg</prgn>
8543 for managing various system configuration and similar issues,
8544 such as <prgn>update-rc.d</prgn> and
8545 <prgn>install-info</prgn>, are not described in detail here -
8546 please see their manpages.
8550 It is assumed that the reader is reasonably familiar with the
8551 <prgn>dpkg</prgn> System Administrators' manual.
8552 Unfortunately this manual does not yet exist.
8556 The Debian version of the FSF's GNU hello program is provided
8557 as an example for people wishing to create Debian
8558 packages. The Debian <prgn>debmake</prgn> package is
8559 recommended as a very helpful tool in creating and maintaining
8560 Debian packages. However, while the tools and examples are
8561 helpful, they do not replace the need to read and follow the
8562 Policy and Programmer's Manual.</p>
8565 <appendix id="pkg-binarypkg">
8566 <heading>Binary packages (from old Packaging Manual)</heading>
8569 The binary package has two main sections. The first part
8570 consists of various control information files and scripts used
8571 by <prgn>dpkg</prgn> when installing and removing. See <ref
8572 id="pkg-controlarea">.
8576 The second part is an archive containing the files and
8577 directories to be installed.
8581 In the future binary packages may also contain other
8582 components, such as checksums and digital signatures. The
8583 format for the archive is described in full in the
8584 <file>deb(5)</file> manpage.
8588 <sect id="pkg-bincreating"><heading>Creating package files -
8589 <prgn>dpkg-deb</prgn>
8593 All manipulation of binary package files is done by
8594 <prgn>dpkg-deb</prgn>; it's the only program that has
8595 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
8596 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
8597 will spot that the options requested are appropriate to
8598 <prgn>dpkg-deb</prgn> and invoke that instead with the same
8603 In order to create a binary package you must make a
8604 directory tree which contains all the files and directories
8605 you want to have in the filesystem data part of the package.
8606 In Debian-format source packages this directory is usually
8607 <file>debian/tmp</file>, relative to the top of the package's
8612 They should have the locations (relative to the root of the
8613 directory tree you're constructing) ownerships and
8614 permissions which you want them to have on the system when
8619 With current versions of <prgn>dpkg</prgn> the uid/username
8620 and gid/groupname mappings for the users and groups being
8621 used should be the same on the system where the package is
8622 built and the one where it is installed.
8626 You need to add one special directory to the root of the
8627 miniature filesystem tree you're creating:
8628 <prgn>DEBIAN</prgn>. It should contain the control
8629 information files, notably the binary package control file
8630 (see <ref id="pkg-controlfile">).
8634 The <prgn>DEBIAN</prgn> directory will not appear in the
8635 filesystem archive of the package, and so won't be installed
8636 by <prgn>dpkg</prgn> when the package is installed.
8640 When you've prepared the package, you should invoke:
8642 dpkg --build <var>directory</var>
8647 This will build the package in
8648 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
8649 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
8650 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
8655 See the manpage <manref name="dpkg-deb" section="8"> for details of how
8656 to examine the contents of this newly-created file. You may find the
8657 output of following commands enlightening:
8659 dpkg-deb --info <var>filename</var>.deb
8660 dpkg-deb --contents <var>filename</var>.deb
8661 dpkg --contents <var>filename</var>.deb
8663 To view the copyright file for a package you could use this command:
8665 dpkg --fsys-tarfile <var>filename</var>.deb | tar xof usr/share/doc/<var>\*</var>copyright | less
8670 <sect id="pkg-controlarea">
8671 <heading>Package control information files</heading>
8674 The control information portion of a binary package is a
8675 collection of files with names known to <prgn>dpkg</prgn>.
8676 It will treat the contents of these files specially - some
8677 of them contain information used by <prgn>dpkg</prgn> when
8678 installing or removing the package; others are scripts which
8679 the package maintainer wants <prgn>dpkg</prgn> to run.
8683 It is possible to put other files in the package control
8684 area, but this is not generally a good idea (though they
8685 will largely be ignored).
8689 Here is a brief list of the control info files supported by
8690 <prgn>dpkg</prgn> and a summary of what they're used for.
8695 <tag><tt>control</tt>
8698 This is the key description file used by
8699 <prgn>dpkg</prgn>. It specifies the package's name
8700 and version, gives its description for the user,
8701 states its relationships with other packages, and so
8702 forth. See <ref id="sourcecontrolfiles"> and
8703 <ref id="binarycontrolfiles">.
8707 It is usually generated automatically from information
8708 in the source package by the
8709 <prgn>dpkg-gencontrol</prgn> program, and with
8710 assistance from <prgn>dpkg-shlibdeps</prgn>.
8711 See <ref id="pkg-sourcetools">.
8715 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
8720 These are exectuable files (usually scripts) which
8721 <prgn>dpkg</prgn> runs during installation, upgrade
8722 and removal of packages. They allow the package to
8723 deal with matters which are particular to that package
8724 or require more complicated processing than that
8725 provided by <prgn>dpkg</prgn>. Details of when and
8726 how they are called are in <ref id="maintainerscripts">.
8730 It is very important to make these scripts idempotent.
8731 See <ref id="idempotency">.
8735 The maintainer scripts are guaranteed to run with a
8736 controlling terminal and can interact with the user.
8737 See <ref id="controllingterminal">.
8741 <tag><tt>conffiles</tt>
8744 This file contains a list of configuration files which
8745 are to be handled automatically by <prgn>dpkg</prgn>
8746 (see <ref id="pkg-conffiles">). Note that not necessarily
8747 every configuration file should be listed here.
8750 <tag><tt>shlibs</tt>
8753 This file contains a list of the shared libraries
8754 supplied by the package, with dependency details for
8755 each. This is used by <prgn>dpkg-shlibdeps</prgn>
8756 when it determines what dependencies are required in a
8757 package control file. The <tt>shlibs</tt> file format
8758 is described on <ref id="shlibs">.
8763 <sect id="pkg-controlfile">
8764 <heading>The main control information file: <tt>control</tt></heading>
8767 The most important control information file used by
8768 <prgn>dpkg</prgn> when it installs a package is
8769 <tt>control</tt>. It contains all the package's "vital
8774 The binary package control files of packages built from
8775 Debian sources are made by a special tool,
8776 <prgn>dpkg-gencontrol</prgn>, which reads
8777 <file>debian/control</file> and <file>debian/changelog</file> to
8778 find the information it needs. See <ref id="pkg-sourcepkg"> for
8783 The fields in binary package control files are listed in
8784 <ref id="binarycontrolfiles">.
8788 A description of the syntax of control files and the purpose
8789 of the fields is available in <ref id="controlfields">.
8794 <heading>Time Stamps</heading>
8797 See <ref id="timestamps">.
8802 <appendix id="pkg-sourcepkg">
8803 <heading>Source packages (from old Packaging Manual) </heading>
8806 The Debian binary packages in the distribution are generated
8807 from Debian sources, which are in a special format to assist
8808 the easy and automatic building of binaries.
8811 <sect id="pkg-sourcetools">
8812 <heading>Tools for processing source packages</heading>
8815 Various tools are provided for manipulating source packages;
8816 they pack and unpack sources and help build of binary
8817 packages and help manage the distribution of new versions.
8821 They are introduced and typical uses described here; see
8822 <manref name="dpkg-source" section="1"> for full
8823 documentation about their arguments and operation.
8827 For examples of how to construct a Debian source package,
8828 and how to use those utilities that are used by Debian
8829 source packages, please see the <prgn>hello</prgn> example
8835 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
8840 This program is frequently used by hand, and is also
8841 called from package-independent automated building scripts
8842 such as <prgn>dpkg-buildpackage</prgn>.
8846 To unpack a package it is typically invoked with
8848 dpkg-source -x <var>.../path/to/filename</var>.dsc
8853 with the <file><var>filename</var>.tar.gz</file> and
8854 <file><var>filename</var>.diff.gz</file> (if applicable) in
8855 the same directory. It unpacks into
8856 <file><var>package</var>-<var>version</var></file>, and if
8858 <file><var>package</var>-<var>version</var>.orig</file>, in
8859 the current directory.
8863 To create a packed source archive it is typically invoked:
8865 dpkg-source -b <var>package</var>-<var>version</var>
8870 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
8871 <file>.diff.gz</file> (if appropriate) in the current
8872 directory. <prgn>dpkg-source</prgn> does not clean the
8873 source tree first - this must be done separately if it is
8878 See also <ref id="pkg-sourcearchives">.</p>
8884 <prgn>dpkg-buildpackage</prgn> - overall package-building
8889 <prgn>dpkg-buildpackage</prgn> is a script which invokes
8890 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
8891 targets <tt>clean</tt>, <tt>build</tt> and
8892 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
8893 <prgn>pgp</prgn> to build a signed source and binary
8898 It is usually invoked by hand from the top level of the
8899 built or unbuilt source directory. It may be invoked with
8900 no arguments; useful arguments include:
8901 <taglist compact="compact">
8902 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
8905 Do not PGP-sign the <tt>.changes</tt> file or the
8906 source package <tt>.dsc</tt> file, respectively.</p>
8908 <tag><tt>-p<var>pgp-command</var></tt></tag>
8911 Invoke <var>pgp-command</var> instead of finding
8912 <tt>pgp</tt> on the <prgn>PATH</prgn>.
8913 <var>pgp-command</var> must behave just like
8914 <prgn>pgp</prgn>.</p>
8916 <tag><tt>-r<var>root-command</var></tt></tag>
8919 When root privilege is required, invoke the command
8920 <var>root-command</var>. <var>root-command</var>
8921 should invoke its first argument as a command, from
8922 the <prgn>PATH</prgn> if necessary, and pass its
8923 second and subsequent arguments to the command it
8924 calls. If no <var>root-command</var> is supplied
8925 then <var>dpkg-buildpackage</var> will take no
8926 special action to gain root privilege, so that for
8927 most packages it will have to be invoked as root to
8930 <tag><tt>-b</tt>, <tt>-B</tt></tag>
8933 Two types of binary-only build and upload - see
8934 <manref name="dpkg-source" section="1">.
8943 <prgn>dpkg-gencontrol</prgn> - generates binary package
8948 This program is usually called from <file>debian/rules</file>
8949 (see <ref id="pkg-sourcetree">) in the top level of the source
8954 This is usually done just before the files and directories in the
8955 temporary directory tree where the package is being built have their
8956 permissions and ownerships set and the package is constructed using
8957 <prgn>dpkg-deb/</prgn>
8959 This is so that the control file which is produced has
8960 the right permissions
8965 <prgn>dpkg-gencontrol</prgn> must be called after all the
8966 files which are to go into the package have been placed in
8967 the temporary build directory, so that its calculation of
8968 the installed size of a package is correct.
8972 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
8973 be run after <prgn>dpkg-shlibdeps</prgn> so that the
8974 variable substitutions created by
8975 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
8980 For a package which generates only one binary package, and
8981 which builds it in <file>debian/tmp</file> relative to the top
8982 of the source package, it is usually sufficient to call
8983 <prgn>dpkg-gencontrol</prgn>.
8987 Sources which build several binaries will typically need
8990 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
8991 </example> The <tt>-P</tt> tells
8992 <prgn>dpkg-gencontrol</prgn> that the package is being
8993 built in a non-default directory, and the <tt>-p</tt>
8994 tells it which package's control file should be generated.
8998 <prgn>dpkg-gencontrol</prgn> also adds information to the
8999 list of files in <file>debian/files</file>, for the benefit of
9000 (for example) a future invocation of
9001 <prgn>dpkg-genchanges</prgn>.</p>
9006 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9011 This program is usually called from <file>debian/rules</file>
9012 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9013 id="pkg-sourcetree">), in the top level of the source tree.
9017 Its arguments are executables.
9020 In a forthcoming dpkg version,
9021 <prgn>dpkg-shlibdeps</prgn> would be required to be
9022 called on shared libraries as well.
9025 They may be specified either in the locations in the
9026 source tree where they are created or in the locations
9027 in the temporary build tree where they are installed
9028 prior to binary package creation.
9030 </footnote> for which shared library dependencies should
9031 be included in the binary package's control file.
9035 If some of the found shared libraries should only
9036 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9037 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9038 by using the <tt>-d<var>dependency-field</var></tt> option
9039 before those executable(s). (Each <tt>-d</tt> option
9040 takes effect until the next <tt>-d</tt>.)
9044 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9045 output control file to be modified. Instead by default it
9046 adds to the <file>debian/substvars</file> file variable
9047 settings like <tt>shlibs:Depends</tt>. These variable
9048 settings must be referenced in dependency fields in the
9049 appropriate per-binary-package sections of the source
9054 For example, the <prgn>procps</prgn> package generates two
9055 kinds of binaries, simple C binaries like <prgn>ps</prgn>
9056 which require a predependency and full-screen ncurses
9057 binaries like <prgn>top</prgn> which require only a
9058 recommendation. It can say in its <file>debian/rules</file>:
9060 dpkg-shlibdeps -dPre-Depends ps -dRecommends top
9062 and then in its main control file <file>debian/control</file>:
9066 Pre-Depends: ${shlibs:Pre-Depends}
9067 Recommends: ${shlibs:Recommends}
9073 Sources which produce several binary packages with
9074 different shared library dependency requirements can use
9075 the <tt>-p<var>varnameprefix</var></tt> option to override
9076 the default <tt>shlibs:</tt> prefix (one invocation of
9077 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9078 They can thus produce several sets of dependency
9079 variables, each of the form
9080 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9081 which can be referred to in the appropriate parts of the
9082 binary package control files.
9089 <prgn>dpkg-distaddfile</prgn> - adds a file to
9090 <file>debian/files</file>
9094 Some packages' uploads need to include files other than
9095 the source and binary package files.
9099 <prgn>dpkg-distaddfile</prgn> adds a file to the
9100 <file>debian/files</file> file so that it will be included in
9101 the <file>.changes</file> file when
9102 <prgn>dpkg-genchanges</prgn> is run.
9106 It is usually invoked from the <tt>binary</tt> target of
9107 <file>debian/rules</file>:
9109 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9111 The <var>filename</var> is relative to the directory where
9112 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9113 is usually the directory above the top level of the source
9114 tree. The <file>debian/rules</file> target should put the
9115 file there just before or just after calling
9116 <prgn>dpkg-distaddfile</prgn>.
9120 The <var>section</var> and <var>priority</var> are passed
9121 unchanged into the resulting <file>.changes</file> file.
9126 <sect1><heading><prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file> upload
9131 This program is usually called by package-independent
9132 automatic building scripts such as
9133 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9138 It is usually called in the top level of a built source
9139 tree, and when invoked with no arguments will print out a
9140 straightforward <file>.changes</file> file based on the
9141 information in the source package's changelog and control
9142 file and the binary and source packages which should have
9148 <sect1><heading><prgn>dpkg-parsechangelog</prgn> - produces parsed representation of
9153 This program is used internally by
9154 <prgn>dpkg-source</prgn> et al. It may also occasionally
9155 be useful in <file>debian/rules</file> and elsewhere. It
9156 parses a changelog, <file>debian/changelog</file> by default,
9157 and prints a control-file format representation of the
9158 information in it to standard output.
9162 <sect1 id="pkg-dpkgarch"><heading><prgn>dpkg-architecture</prgn> -
9163 information about the build and host system
9167 This program can be used manually, but is also invoked by
9168 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9169 to set environment or make variables which specify the build and
9170 host architecture for the package building process.
9175 <sect id="pkg-sourcetree">
9176 <heading>The Debianised source tree</heading>
9179 The source archive scheme described later is intended to
9180 allow a Debianised source tree with some associated control
9181 information to be reproduced and transported easily. The
9182 Debianised source tree is a version of the original program
9183 with certain files added for the benefit of the
9184 Debianisation process, and with any other changes required
9185 made to the rest of the source code and installation
9190 The extra files created for Debian are in the subdirectory
9191 <file>debian</file> of the top level of the Debianised source
9192 tree. They are described below.
9195 <sect1 id="pkg-debianrules">
9196 <heading><file>debian/rules</file> - the main building script</heading>
9199 See <ref id="debianrules">.
9204 <sect1 id="pkg-dpkgchangelog">
9205 <heading><file>debian/changelog</file></heading>
9208 See <ref id="dpkgchangelog">.
9212 It is recommended that the entire changelog be encoded in the
9213 <url id="http://www.cis.ohio-state.edu/cgi-bin/rfc/rfc2279.html" name="UTF-8">
9215 <url id="http://www.unicode.org/"
9216 name="Unicode">.<footnote>
9218 Support for Unicode, and specifically UTF-8, is
9219 steadily increasing among popular applications in
9220 Debian. For example, in unstable, GNOME 2 has
9221 excellent support (almost level 2) in almost all its
9222 applications; the big remaining one is gnome-terminal,
9223 of which one requires development versions in order to
9224 support UTF-8 (available in Debian experimental now if
9225 you want to play). I think that by the time sarge is
9226 released, UTF-8 support will start to hit critical
9229 I think it is fairly obvious that we need to
9230 eventually transition to UTF-8 for our package
9231 infrastructure; it is really the only sane charset in
9232 an international environment. Now, we can't switch to
9233 using UTF-8 for package control fields and the like
9234 until dpkg has better support, but one thing we can
9235 start doing today is requesting that Debian changelogs
9236 are UTF-8 encoded. At some point in time, we can start
9237 requiring them to do so.
9240 Checking for non-UTF8 characters in a changelog is
9241 trivial. Dump the file through
9242 <example>iconv -f utf-8 -t ucs-4</example>
9243 discard the output, and check the return
9244 value. If there are any characters in the stream
9245 which are invalid UTF-8 sequences, iconv will exit
9246 with an error code; and this will be the case for the
9247 vast majority of other character sets.
9252 <sect2><heading>Defining alternative changelog formats
9256 It is possible to use a different format to the standard
9257 one, by providing a parser for the format you wish to
9262 In order to have <tt>dpkg-parsechangelog</tt> run your
9263 parser, you must include a line within the last 40 lines
9264 of your file matching the Perl regular expression:
9265 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9266 parentheses should be the name of the format. For
9267 example, you might say:
9269 @@@ changelog-format: joebloggs @@@
9271 Changelog format names are non-empty strings of alphanumerics.
9275 If such a line exists then <tt>dpkg-parsechangelog</tt>
9276 will look for the parser as
9277 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9279 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9280 it is an error for it not to find it, or for it not to
9281 be an executable program. The default changelog format
9282 is <tt>dpkg</tt>, and a parser for it is provided with
9283 the <tt>dpkg</tt> package.
9287 The parser will be invoked with the changelog open on
9288 standard input at the start of the file. It should read
9289 the file (it may seek if it wishes) to determine the
9290 information required and return the parsed information
9291 to standard output in the form of a series of control
9292 fields in the standard format. By default it should
9293 return information about only the most recent version in
9294 the changelog; it should accept a
9295 <tt>-v<var>version</var></tt> option to return changes
9296 information from all versions present <em>strictly
9297 after</em> <var>version</var>, and it should then be an
9298 error for <var>version</var> not to be present in the
9304 <list compact="compact">
9305 <item><qref id="f-Source"><tt>Source</tt></qref></item>
9306 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
9307 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
9308 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
9309 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
9310 <item><qref id="f-Date"><tt>Date</tt></qref></item>
9311 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
9316 If several versions are being returned (due to the use
9317 of <tt>-v</tt>), the urgency value should be of the
9318 highest urgency code listed at the start of any of the
9319 versions requested followed by the concatenated
9320 (space-separated) comments from all the versions
9321 requested; the maintainer, version, distribution and
9322 date should always be from the most recent version.
9326 For the format of the <tt>Changes</tt> field see
9327 <ref id="f-Changes">.
9331 If the changelog format which is being parsed always or
9332 almost always leaves a blank line between individual
9333 change notes these blank lines should be stripped out,
9334 so as to make the resulting output compact.
9338 If the changelog format does not contain date or package
9339 name information this information should be omitted from
9340 the output. The parser should not attempt to synthesise
9341 it or find it from other sources.
9345 If the changelog does not have the expected format the
9346 parser should exit with a nonzero exit status, rather
9347 than trying to muddle through and possibly generating
9352 A changelog parser may not interact with the user at
9358 <sect1 id="pkg-srcsubstvars">
9359 <heading><file>debian/substvars</file> and variable substitutions</heading>
9362 See <ref id="substvars">.
9368 <heading><file>debian/files</file></heading>
9371 See <ref id="debianfiles">.
9375 <sect1><heading><file>debian/tmp</file>
9379 This is the canonical temporary location for the
9380 construction of binary packages by the <tt>binary</tt>
9381 target. The directory <file>tmp</file> serves as the root of
9382 the filesystem tree as it is being constructed (for
9383 example, by using the package's upstream makefiles install
9384 targets and redirecting the output there), and it also
9385 contains the <tt>DEBIAN</tt> subdirectory. See <ref
9386 id="pkg-bincreating">.
9390 If several binary packages are generated from the same
9391 source tree it is usual to use several
9392 <file>debian/tmp<var>something</var></file> directories, for
9393 example <file>tmp-a</file> or <file>tmp-doc</file>.
9397 Whatever <file>tmp</file> directories are created and used by
9398 <tt>binary</tt> must of course be removed by the
9399 <tt>clean</tt> target.</p></sect1>
9403 <sect id="pkg-sourcearchives"><heading>Source packages as archives
9407 As it exists on the FTP site, a Debian source package
9408 consists of three related files. You must have the right
9409 versions of all three to be able to use them.
9414 <tag>Debian source control file - <tt>.dsc</tt></tag>
9416 This file is a control file used by <prgn>dpkg-source</prgn>
9417 to extract a source package.
9418 See <ref id="debiansourcecontrolfiles">.
9422 Original source archive -
9424 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
9431 This is a compressed (with <tt>gzip -9</tt>)
9432 <prgn>tar</prgn> file containing the source code from
9433 the upstream authors of the program. The tarfile
9434 unpacks into a directory
9435 <file><var>package</var>-<var>upstream-version</var>.orig</file>,
9436 and does not contain files anywhere other than in
9437 there or in its subdirectories.</p>
9441 Debianisation diff -
9443 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
9449 This is a unified context diff (<tt>diff -u</tt>)
9450 giving the changes which are required to turn the
9451 original source into the Debian source. These changes
9452 may only include editing and creating plain files.
9453 The permissions of files, the targets of symbolic
9454 links and the characteristics of special files or
9455 pipes may not be changed and no files may be removed
9460 All the directories in the diff must exist, except the
9461 <file>debian</file> subdirectory of the top of the source
9462 tree, which will be created by
9463 <prgn>dpkg-source</prgn> if necessary when unpacking.
9467 The <prgn>dpkg-source</prgn> program will
9468 automatically make the <file>debian/rules</file> file
9469 executable (see below).</p></item>
9474 If there is no original source code - for example, if the
9475 package is specially prepared for Debian or the Debian
9476 maintainer is the same as the upstream maintainer - the
9477 format is slightly different: then there is no diff, and the
9479 <file><var>package</var>_<var>version</var>.tar.gz</file> and
9480 contains a directory
9481 <file><var>package</var>-<var>version</var></file>.
9486 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
9489 <tt>dpkg-source -x</tt> is the recommended way to unpack a
9490 Debian source package. However, if it is not available it
9491 is possible to unpack a Debian source archive as follows:
9492 <enumlist compact="compact">
9495 Untar the tarfile, which will create a <file>.orig</file>
9499 <p>Rename the <file>.orig</file> directory to
9500 <file><var>package</var>-<var>version</var></file>.</p>
9504 Create the subdirectory <file>debian</file> at the top of
9505 the source tree.</p>
9507 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
9509 <item><p>Untar the tarfile again if you want a copy of the original
9510 source code alongside the Debianised version.</p>
9515 It is not possible to generate a valid Debian source archive
9516 without using <prgn>dpkg-source</prgn>. In particular,
9517 attempting to use <prgn>diff</prgn> directly to generate the
9518 <file>.diff.gz</file> file will not work.
9522 <heading>Restrictions on objects in source packages</heading>
9525 The source package may not contain any hard links
9527 This is not currently detected when building source
9528 packages, but only when extracting
9532 Hard links may be permitted at some point in the
9533 future, but would require a fair amount of
9535 </footnote>, device special files, sockets or setuid or
9538 Setgid directories are allowed.
9543 The source packaging tools manage the changes between the
9544 original and Debianised source using <prgn>diff</prgn> and
9545 <prgn>patch</prgn>. Turning the original source tree as
9546 included in the <file>.orig.tar.gz</file> into the debianised
9547 source must not involve any changes which cannot be
9548 handled by these tools. Problematic changes which cause
9549 <prgn>dpkg-source</prgn> to halt with an error when
9550 building the source package are:
9551 <list compact="compact">
9552 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
9554 <item><p>Changing the targets of symbolic links.</p>
9556 <item><p>Creating directories, other than <file>debian</file>.</p>
9558 <item><p>Changes to the contents of binary files.</p></item>
9559 </list> Changes which cause <prgn>dpkg-source</prgn> to
9560 print a warning but continue anyway are:
9561 <list compact="compact">
9564 Removing files, directories or symlinks.
9566 Renaming a file is not treated specially - it is
9567 seen as the removal of the old file (which
9568 generates a warning, but is otherwise ignored),
9569 and the creation of the new one.
9575 Changed text files which are missing the usual final
9576 newline (either in the original or the modified
9581 Changes which are not represented, but which are not detected by
9582 <prgn>dpkg-source</prgn>, are:
9583 <list compact="compact">
9584 <item><p>Changing the permissions of files (other than
9585 <file>debian/rules</file>) and directories.</p></item>
9590 The <file>debian</file> directory and <file>debian/rules</file>
9591 are handled specially by <prgn>dpkg-source</prgn> - before
9592 applying the changes it will create the <file>debian</file>
9593 directory, and afterwards it will make
9594 <file>debian/rules</file> world-exectuable.
9600 <appendix id="pkg-controlfields">
9601 <heading>Control files and their fields (from old Packaging Manual)</heading>
9604 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
9605 data in a common format, known as control files. Binary and
9606 source packages have control data as do the <file>.changes</file>
9607 files which control the installation of uploaded files, and
9608 <prgn>dpkg</prgn>'s internal databases are in a similar
9613 <heading>Syntax of control files</heading>
9616 See <ref id="controlsyntax">.
9620 It is important to note that there are several fields which
9621 are optional as far as <prgn>dpkg</prgn> and the related
9622 tools are concerned, but which must appear in every Debian
9623 package, or whose omission may cause problems.
9628 <heading>List of fields</heading>
9631 See <ref id="controlfieldslist">.
9635 This section now contains only the fields that didn't belong
9636 to the Policy manual.
9639 <sect1 id="pkg-f-Filename">
9640 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
9643 These fields in <tt>Packages</tt> files give the
9644 filename(s) of (the parts of) a package in the
9645 distribution directories, relative to the root of the
9646 Debian hierarchy. If the package has been split into
9647 several parts the parts are all listed in order, separated
9652 <sect1 id="pkg-f-Size">
9653 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
9656 These fields in <file>Packages</file> files give the size (in
9657 bytes, expressed in decimal) and MD5 checksum of the
9658 file(s) which make(s) up a binary package in the
9659 distribution. If the package is split into several parts
9660 the values for the parts are listed in order, separated by
9665 <sect1 id="pkg-f-Status">
9666 <heading><tt>Status</tt></heading>
9669 This field in <prgn>dpkg</prgn>'s status file records
9670 whether the user wants a package installed, removed or
9671 left alone, whether it is broken (requiring
9672 reinstallation) or not and what its current state on the
9673 system is. Each of these pieces of information is a
9678 <sect1 id="pkg-f-Config-Version">
9679 <heading><tt>Config-Version</tt></heading>
9682 If a package is not installed or not configured, this
9683 field in <prgn>dpkg</prgn>'s status file records the last
9684 version of the package which was successfully
9689 <sect1 id="pkg-f-Conffiles">
9690 <heading><tt>Conffiles</tt></heading>
9693 This field in <prgn>dpkg</prgn>'s status file contains
9694 information about the automatically-managed configuration
9695 files held by a package. This field should <em>not</em>
9696 appear anywhere in a package!
9701 <heading>Obsolete fields</heading>
9704 These are still recognised by <prgn>dpkg</prgn> but should
9705 not appear anywhere any more.
9707 <taglist compact="compact">
9709 <tag><tt>Revision</tt></tag>
9710 <tag><tt>Package-Revision</tt></tag>
9711 <tag><tt>Package_Revision</tt></tag>
9713 The Debian revision part of the package version was
9714 at one point in a separate control file field. This
9715 field went through several names.
9718 <tag><tt>Recommended</tt></tag>
9719 <item>Old name for <tt>Recommends</tt>.</item>
9721 <tag><tt>Optional</tt></tag>
9722 <item>Old name for <tt>Suggests</tt>.</item>
9724 <tag><tt>Class</tt></tag>
9725 <item>Old name for <tt>Priority</tt>.</item>
9734 <appendix id="pkg-conffiles">
9735 <heading>Configuration file handling (from old Packaging Manual)</heading>
9738 <prgn>dpkg</prgn> can do a certain amount of automatic
9739 handling of package configuration files.
9743 Whether this mechanism is appropriate depends on a number of
9744 factors, but basically there are two approaches to any
9745 particular configuration file.
9749 The easy method is to ship a best-effort configuration in the
9750 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
9751 handle updates. If the user is unlikely to want to edit the
9752 file, but you need them to be able to without losing their
9753 changes, and a new package with a changed version of the file
9754 is only released infrequently, this is a good approach.
9758 The hard method is to build the configuration file from
9759 scratch in the <prgn>postinst</prgn> script, and to take the
9760 responsibility for fixing any mistakes made in earlier
9761 versions of the package automatically. This will be
9762 appropriate if the file is likely to need to be different on
9766 <sect><heading>Automatic handling of configuration files by
9771 A package may contain a control area file called
9772 <tt>conffiles</tt>. This file should be a list of filenames
9773 of configuration files needing automatic handling, separated
9774 by newlines. The filenames should be absolute pathnames,
9775 and the files referred to should actually exist in the
9780 When a package is upgraded <prgn>dpkg</prgn> will process
9781 the configuration files during the configuration stage,
9782 shortly before it runs the package's <prgn>postinst</prgn>
9787 For each file it checks to see whether the version of the
9788 file included in the package is the same as the one that was
9789 included in the last version of the package (the one that is
9790 being upgraded from); it also compares the version currently
9791 installed on the system with the one shipped with the last
9796 If neither the user nor the package maintainer has changed
9797 the file, it is left alone. If one or the other has changed
9798 their version, then the changed version is preferred - i.e.,
9799 if the user edits their file, but the package maintainer
9800 doesn't ship a different version, the user's changes will
9801 stay, silently, but if the maintainer ships a new version
9802 and the user hasn't edited it the new version will be
9803 installed (with an informative message). If both have
9804 changed their version the user is prompted about the problem
9805 and must resolve the differences themselves.
9809 The comparisons are done by calculating the MD5 message
9810 digests of the files, and storing the MD5 of the file as it
9811 was included in the most recent version of the package.
9815 When a package is installed for the first time
9816 <prgn>dpkg</prgn> will install the file that comes with it,
9817 unless that would mean overwriting a file already on the
9822 However, note that <prgn>dpkg</prgn> will <em>not</em>
9823 replace a conffile that was removed by the user (or by a
9824 script). This is necessary because with some programs a
9825 missing file produces an effect hard or impossible to
9826 achieve in another way, so that a missing file needs to be
9827 kept that way if the user did it.
9831 Note that a package should <em>not</em> modify a
9832 <prgn>dpkg</prgn>-handled conffile in its maintainer
9833 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
9834 the user confusing and possibly dangerous options for
9835 conffile update when the package is upgraded.</p>
9838 <sect><heading>Fully-featured maintainer script configuration
9843 For files which contain site-specific information such as
9844 the hostname and networking details and so forth, it is
9845 better to create the file in the package's
9846 <prgn>postinst</prgn> script.
9850 This will typically involve examining the state of the rest
9851 of the system to determine values and other information, and
9852 may involve prompting the user for some information which
9853 can't be obtained some other way.
9857 When using this method there are a couple of important
9858 issues which should be considered:
9862 If you discover a bug in the program which generates the
9863 configuration file, or if the format of the file changes
9864 from one version to the next, you will have to arrange for
9865 the postinst script to do something sensible - usually this
9866 will mean editing the installed configuration file to remove
9867 the problem or change the syntax. You will have to do this
9868 very carefully, since the user may have changed the file,
9869 perhaps to fix the very problem that your script is trying
9870 to deal with - you will have to detect these situations and
9871 deal with them correctly.
9875 If you do go down this route it's probably a good idea to
9876 make the program that generates the configuration file(s) a
9877 separate program in <file>/usr/sbin</file>, by convention called
9878 <file><var>package</var>config</file> and then run that if
9879 appropriate from the post-installation script. The
9880 <tt><var>package</var>config</tt> program should not
9881 unquestioningly overwrite an existing configuration - if its
9882 mode of operation is geared towards setting up a package for
9883 the first time (rather than any arbitrary reconfiguration
9884 later) you should have it check whether the configuration
9885 already exists, and require a <tt>--force</tt> flag to
9886 overwrite it.</p></sect>
9889 <appendix id="pkg-alternatives"><heading>Alternative versions of
9890 an interface - <prgn>update-alternatives</prgn> (from old
9895 When several packages all provide different versions of the
9896 same program or file it is useful to have the system select a
9897 default, but to allow the system administrator to change it
9898 and have their decisions respected.
9902 For example, there are several versions of the <prgn>vi</prgn>
9903 editor, and there is no reason to prevent all of them from
9904 being installed at once, each under their own name
9905 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
9906 Nevertheless it is desirable to have the name <tt>vi</tt>
9907 refer to something, at least by default.
9911 If all the packages involved cooperate, this can be done with
9912 <prgn>update-alternatives</prgn>.
9916 Each package provides its own version under its own name, and
9917 calls <prgn>update-alternatives</prgn> in its postinst to
9918 register its version (and again in its prerm to deregister
9923 See the manpage <manref name="update-alternatives"
9924 section="8"> for details.
9928 If <prgn>update-alternatives</prgn> does not seem appropriate
9929 you may wish to consider using diversions instead.</p>
9932 <appendix id="pkg-diversions"><heading>Diversions - overriding a
9933 package's version of a file (from old Packaging Manual)
9937 It is possible to have <prgn>dpkg</prgn> not overwrite a file
9938 when it reinstalls the package it belongs to, and to have it
9939 put the file from the package somewhere else instead.
9943 This can be used locally to override a package's version of a
9944 file, or by one package to override another's version (or
9945 provide a wrapper for it).
9949 Before deciding to use a diversion, read <ref
9950 id="pkg-alternatives"> to see if you really want a diversion
9951 rather than several alternative versions of a program.
9955 There is a diversion list, which is read by <prgn>dpkg</prgn>,
9956 and updated by a special program <prgn>dpkg-divert</prgn>.
9957 Please see <manref name="dpkg-divert" section="8"> for full
9958 details of its operation.
9962 When a package wishes to divert a file from another, it should
9963 call <prgn>dpkg-divert</prgn> in its preinst to add the
9964 diversion and rename the existing file. For example,
9965 supposing that a <prgn>smailwrapper</prgn> package wishes to
9966 install a wrapper around <file>/usr/sbin/smail</file>:
9968 if [ install = "$1" ]; then
9969 dpkg-divert --package smailwrapper --add --rename \
9970 --divert /usr/sbin/smail.real /usr/sbin/smail
9972 </example> Testing <tt>$1</tt> is necessary so that the script
9973 doesn't try to add the diversion again when
9974 <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
9975 smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
9976 copy of <file>/usr/sbin/smail</file> can bypass the diversion and
9977 get installed as the true version.
9981 The postrm has to do the reverse:
9983 if [ remove = "$1" ]; then
9984 dpkg-divert --package smailwrapper --remove --rename \
9985 --divert /usr/sbin/smail.real /usr/sbin/smail
9991 Do not attempt to divert a file which is vitally important for
9992 the system's operation - when using <prgn>dpkg-divert</prgn>
9993 there is a time, after it has been diverted but before
9994 <prgn>dpkg</prgn> has installed the new version, when the file
10000 <!-- vim:set ai et sts=2 sw=2 tw=76: -->