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10 <title>Debian Policy Manual</title>
11 <author><qref id="authors">The Debian Policy Mailing List</qref></author>
12 <version>version &version;, &date;</version>
15 This manual describes the policy requirements for the Debian
16 GNU/Linux distribution. This includes the structure and
17 contents of the Debian archive and several design issues of
18 the operating system, as well as technical requirements that
19 each package must satisfy to be included in the distribution.
24 Copyright © 1996,1997,1998 Ian Jackson
25 and Christian Schwarz.
28 This manual is free software; you may redistribute it and/or
29 modify it under the terms of the GNU General Public License
30 as published by the Free Software Foundation; either version
31 2, or (at your option) any later version.
35 This is distributed in the hope that it will be useful, but
36 <em>without any warranty</em>; without even the implied
37 warranty of merchantability or fitness for a particular
38 purpose. See the GNU General Public License for more
43 A copy of the GNU General Public License is available as
44 <file>/usr/share/common-licenses/GPL</file> in the Debian GNU/Linux
45 distribution or on the World Wide Web at
46 <url id="http://www.gnu.org/copyleft/gpl.html"
47 name="the GNU General Public Licence">. You can also
48 obtain it by writing to the Free Software Foundation, Inc.,
49 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
57 <heading>About this manual</heading>
59 <heading>Scope</heading>
61 This manual describes the policy requirements for the Debian
62 GNU/Linux distribution. This includes the structure and
63 contents of the Debian archive and several design issues of the
64 operating system, as well as technical requirements that
65 each package must satisfy to be included in the
70 This manual also describes Debian policy as it relates to
71 creating Debian packages. It is not a tutorial on how to build
72 packages, nor is it exhaustive where it comes to describing
73 the behavior of the packaging system. Instead, this manual
74 attempts to define the interface to the package management
75 system that the developers have to be conversant with.<footnote>
76 Informally, the criteria used for inclusion is that the
77 material meet one of the following requirements:
78 <taglist compact="compact">
79 <tag>Standard interfaces</tag>
81 The material presented represents an interface to
82 the packaging system that is mandated for use, and
83 is used by, a significant number of packages, and
84 therefore should not be changed without peer
85 review. Package maintainers can then rely on this
86 interfaces not changing, and the package
87 management software authors need to ensure
88 compatibility with these interface
89 definitions. (Control file and changelog file
90 formats are examples.)
92 <tag>Chosen Convention</tag>
94 If there are a number of technically viable choices
95 that can be made, but one needs to select one of
96 these options for inter-operability. The version
97 number format is one example.
100 Please note that these are not mutually exclusive;
101 selected conventions often become parts of standard
107 The footnotes present in this manual are
108 merely informative, and are not part of Debian policy itself.
112 The appendices to this manual are not necessarily normative,
113 either. Please see <ref id="pkg-scope"> for more information.
117 In the normative part of this manual,
118 the words <em>must</em>, <em>should</em> and
119 <em>may</em>, and the adjectives <em>required</em>,
120 <em>recommended</em> and <em>optional</em>, are used to
121 distinguish the significance of the various guidelines in
122 this policy document. Packages that do not conform to the
123 guidelines denoted by <em>must</em> (or <em>required</em>)
124 will generally not be considered acceptable for the Debian
125 distribution. Non-conformance with guidelines denoted by
126 <em>should</em> (or <em>recommended</em>) will generally be
127 considered a bug, but will not necessarily render a package
128 unsuitable for distribution. Guidelines denoted by
129 <em>may</em> (or <em>optional</em>) are truly optional and
130 adherence is left to the maintainer's discretion.
134 These classifications are roughly equivalent to the bug
135 severities <em>serious</em> (for <em>must</em> or
136 <em>required</em> directive violations), <em>minor</em>,
137 <em>normal</em> or <em>important</em>
138 (for <em>should</em> or <em>recommended</em> directive
139 violations) and <em>wishlist</em> (for <em>optional</em>
142 Compare RFC 2119. Note, however, that these words are
143 used in a different way in this document.
148 Much of the information presented in this manual will be
149 useful even when building a package which is to be
150 distributed in some other way or is intended for local use
156 <heading>New versions of this document</heading>
159 This manual is distributed via the Debian package
160 <package>debian-policy</package>.
164 The current version of this document is also available from
165 the Debian web mirrors at
166 <tt><url name="/doc/debian-policy/"
167 id="http://www.debian.org/doc/debian-policy/"></tt>
168 and from the Debian archive mirrors at
169 <tt><url name="/doc/package-developer/policy.txt.gz"
170 id="http://ftp.debian.org/debian/doc/package-developer/policy.txt.gz"></tt>.
171 Also available from the same directory are several other
172 formats: <file>policy.html.tar.gz</file>, <file>policy.pdf.gz</file>
173 and <file>policy.ps.gz</file>.
177 The <package>debian-policy</package> package also includes the file
178 <file>upgrading-checklist.txt</file> which indicates policy
179 changes between versions of this document.
184 <heading>Authors and Maintainers</heading>
187 Originally called "Debian GNU/Linux Policy Manual", this
188 manual was initially written in 1996 by Ian Jackson.
189 It was revised on November 27th, 1996 by David A. Morris.
190 Christian Schwarz added new sections on March 15th, 1997,
191 and reworked/restructured it in April-July 1997.
192 Christoph Lameter contributed the "Web Standard".
193 Julian Gilbey largely restructured it in 2001.
197 Since September 1998, the responsibility for the contents of
198 this document lies on the <url name="debian-policy mailing list"
199 id="mailto:debian-policy@lists.debian.org">. Proposals
200 are discussed there and inserted into policy after a certain
201 consensus is established.
202 <!-- insert shameless policy-process plug here eventually -->
203 The actual editing is done by a group of maintainers that have
204 no editorial powers. These are the current maintainers:
207 <item>Julian Gilbey</item>
208 <item>Branden Robinson</item>
209 <item>Josip Rodin</item>
210 <item>Manoj Srivastava</item>
215 While the authors of this document have tried hard to avoid
216 typos and other errors, these do still occur. If you discover
217 an error in this manual or if you want to give any
218 comments, suggestions, or criticisms please send an email to
219 the Debian Policy List,
220 <email>debian-policy@lists.debian.org</email>, or submit a
221 bug report against the <tt>debian-policy</tt> package.
225 Please do not try to reach the individual authors or maintainers
226 of the Policy Manual regarding changes to the Policy.
231 <heading>Related documents</heading>
234 There are several other documents other than this Policy Manual
235 that are necessary to fully understand some Debian policies and
240 The external "sub-policy" documents are referred to in:
241 <list compact="compact">
242 <item><ref id="fhs"></item>
243 <item><ref id="virtual_pkg"></item>
244 <item><ref id="menus"></item>
245 <item><ref id="mime"></item>
246 <item><ref id="perl"></item>
247 <item><ref id="maintscriptprompt"></item>
248 <item><ref id="emacs"></item>
253 In addition to those, which carry the weight of policy, there
254 is the Debian Developer's Reference. This document describes
255 procedures and resources for Debian developers, but it is
256 <em>not</em> normative; rather, it includes things that don't
257 belong into the Policy, such as best practices for developers.
261 The Developer's Reference is available in the
262 <package>developers-reference</package> package.
263 It's also available from the Debian web mirrors at
264 <tt><url name="/doc/developers-reference/"
265 id="http://www.debian.org/doc/developers-reference/"></tt>.
273 <heading>The Debian Archive</heading>
276 The Debian GNU/Linux system is maintained and distributed as a
277 collection of <em>packages</em>. Since there are so many of
278 them (currently well over 6000), they are split into
279 <em>sections</em> and given <em>priorities</em> to simplify
280 the handling of them.
284 The effort of the Debian project is to build a free operating
285 system, but not every package we want to make accessible is
286 <em>free</em> in our sense (see the Debian Free Software
287 Guidelines, below), or may be imported/exported without
288 restrictions. Thus, the archive is split into the sections
289 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
1256 id="http://kitenet.net/doc/debconf-doc/introduction.html"
1257 name="Debconf introduction">; they include
1258 preconfiguration, (mostly) noninteractive
1259 installation, elimination of redundant prompting,
1260 consistency of user interface, etc.
1264 With this increasing number of packages using
1265 <package>debconf</package>, plus the existence of a
1266 nascent second implementation of the Debian
1267 configuration management system
1268 (<package>cdebconf</package>), and the stabilization
1269 of the protocol these things use, the time has
1270 finally come to reflect the use of these things in
1277 The Debian Configuration management specification is included
1278 in the <file>debconf_specification</file> files in the
1279 <package>debian-policy</package> package.
1280 It is also available from the Debian web mirrors at
1281 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1282 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>
1283 and from the Debian archive mirrors at
1284 <tt><url name="/doc/package-developer/debconf_specification.txt.gz"
1285 id="http://ftp.debian.org/debian/doc/package-developer/debconf_specification.txt.gz"></tt>.
1289 Packages which use the Debian Configuration management
1290 specification may contain an additional
1291 <prgn>config</prgn> script and a <tt>templates</tt>
1292 file in their control archive<footnote>
1293 The control.tar.gz inside the .deb.
1294 See <manref name="deb" section="5">.
1296 The <prgn>config</prgn> script might be run before the
1297 <prgn>preinst</prgn> script, and before the package is unpacked
1298 or any of its dependencies or pre-dependancies are satisfied.
1299 Therefore it must work using only the tools present in
1300 <em>essential</em> packages.<footnote>
1301 <package>Debconf</package> or another tool that
1302 implements the Debian Configuration management
1303 specification will also be installed, and any
1304 versioned dependencies on it will be satisfied
1305 before preconfiguration begins.
1310 Packages should try to minimize the amount of prompting
1311 they need to do, and they should ensure that the user
1312 will only ever be asked each question once. This means
1313 that packages should try to use appropriate shared
1314 configuration files (such as <file>/etc/papersize</file> and
1315 <file>/etc/news/server</file>), and shared
1316 <package>debconf</package> variables rather than each
1317 prompting for their own list of required pieces of
1322 It also means that an upgrade should not ask the same
1323 questions again, unless the user has used
1324 <tt>dpkg --purge</tt> to remove the package's configuration.
1325 The answers to configuration questions should be stored in an
1326 appropriate place in <file>/etc</file> so that the user can
1327 modify them, and how this has been done should be
1332 If a package has a vitally important piece of
1333 information to pass to the user (such as "don't run me
1334 as I am, you must edit the following configuration files
1335 first or you risk your system emitting badly-formatted
1336 messages"), it should display this in the
1337 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1338 prompt the user to hit return to acknowledge the
1339 message. Copyright messages do not count as vitally
1340 important (they belong in
1341 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1342 neither do instructions on how to use a program (these
1343 should be in on-line documentation, where all the users
1348 Any necessary prompting should almost always be confined
1349 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1350 script. If it is done in the <prgn>postinst</prgn>, it
1351 should be protected with a conditional so that
1352 unnecessary prompting doesn't happen if a package's
1353 installation fails and the <prgn>postinst</prgn> is
1354 called with <tt>abort-upgrade</tt>,
1355 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1365 <heading>Source packages</heading>
1367 <sect id="standardsversion">
1368 <heading>Standards conformance</heading>
1371 Source packages should specify the most recent version number
1372 of this policy document with which your package complied
1373 when it was last updated.
1377 This information may be used to file bug reports
1378 automatically if your package becomes too much out of date.
1382 The version is specified in the <tt>Standards-Version</tt>
1384 The format of the <tt>Standards-Version</tt> field is
1385 described in <ref id="f-Standards-Version">.
1389 You should regularly, and especially if your package has
1390 become out of date, check for the newest Policy Manual
1391 available and update your package, if necessary. When your
1392 package complies with the new standards you should update the
1393 <tt>Standards-Version</tt> source package field and
1394 release it.<footnote>
1395 See the file <file>upgrading-checklist</file> for
1396 information about policy which has changed between
1397 different versions of this document.
1403 <sect id="pkg-relations">
1404 <heading>Package relationships</heading>
1407 Source packages should specify which binary packages they
1408 require to be installed or not to be installed in order to
1409 build correctly. For example, if building a package
1410 requires a certain compiler, then the compiler should be
1411 specified as a build-time dependency.
1415 It is not necessary to explicitly specify build-time
1416 relationships on a minimal set of packages that are always
1417 needed to compile, link and put in a Debian package a
1418 standard "Hello World!" program written in C or C++. The
1419 required packages are called <em>build-essential</em>, and
1420 an informational list can be found in
1421 <file>/usr/share/doc/build-essential/list</file> (which is
1422 contained in the <tt>build-essential</tt>
1425 <list compact="compact">
1427 This allows maintaining the list separately
1428 from the policy documents (the list does not
1429 need the kind of control that the policy
1433 Having a separate package allows one to install
1434 the build-essential packages on a machine, as
1435 well as allowing other packages such as tasks to
1436 require installation of the build-essential
1437 packages using the depends relation.
1440 The separate package allows bug reports against
1441 the list to be categorized separately from
1442 the policy management process in the BTS.
1449 When specifying the set of build-time dependencies, one
1450 should list only those packages explicitly required by the
1451 build. It is not necessary to list packages which are
1452 required merely because some other package in the list of
1453 build-time dependencies depends on them.<footnote>
1454 The reason for this is that dependencies change, and
1455 you should list all those packages, and <em>only</em>
1456 those packages that <em>you</em> need directly. What
1457 others need is their business. For example, if you
1458 only link against <file>libimlib</file>, you will need to
1459 build-depend on <package>libimlib2-dev</package> but
1460 not against any <tt>libjpeg*</tt> packages, even
1461 though <tt>libimlib2-dev</tt> currently depends on
1462 them: installation of <package>libimlib2-dev</package>
1463 will automatically ensure that all of its run-time
1464 dependencies are satisfied.
1469 If build-time dependencies are specified, it must be
1470 possible to build the package and produce working binaries
1471 on a system with only essential and build-essential
1472 packages installed and also those required to satisfy the
1473 build-time relationships (including any implied
1474 relationships). In particular, this means that version
1475 clauses should be used rigorously in build-time
1476 relationships so that one cannot produce bad or
1477 inconsistently configured packages when the relationships
1478 are properly satisfied.
1482 <ref id="relationships"> explains the technical details.
1487 <heading>Changes to the upstream sources</heading>
1490 If changes to the source code are made that are not
1491 specific to the needs of the Debian system, they should be
1492 sent to the upstream authors in whatever form they prefer
1493 so as to be included in the upstream version of the
1498 If you need to configure the package differently for
1499 Debian or for Linux, and the upstream source doesn't
1500 provide a way to do so, you should add such configuration
1501 facilities (for example, a new <prgn>autoconf</prgn> test
1502 or <tt>#define</tt>) and send the patch to the upstream
1503 authors, with the default set to the way they originally
1504 had it. You can then easily override the default in your
1505 <file>debian/rules</file> or wherever is appropriate.
1509 You should make sure that the <prgn>configure</prgn> utility
1510 detects the correct architecture specification string
1511 (refer to <ref id="arch-spec"> for details).
1515 If you need to edit a <prgn>Makefile</prgn> where
1516 GNU-style <prgn>configure</prgn> scripts are used, you
1517 should edit the <file>.in</file> files rather than editing the
1518 <prgn>Makefile</prgn> directly. This allows the user to
1519 reconfigure the package if necessary. You should
1520 <em>not</em> configure the package and edit the generated
1521 <prgn>Makefile</prgn>! This makes it impossible for
1522 someone else to later reconfigure the package.
1527 <sect id="dpkgchangelog">
1528 <heading>Debian changelog: <file>debian/changelog</file></heading>
1531 Changes in the Debian version of the package should be
1532 briefly explained in the Debian changelog file
1533 <file>debian/changelog</file>. This includes modifications
1534 made in the Debian package compared to the upstream one
1535 as well as other changes and updates to the package.
1537 Although there is nothing stopping an author who is also
1538 the Debian maintainer from using this changelog for all
1539 their changes, it will have to be renamed if the Debian
1540 and upstream maintainers become different people. In such
1541 a case, however, it might be better to maintain the package
1542 as a non-native package.
1547 Mistakes in changelogs are usually best rectified by making
1548 a new changelog entry rather than "rewriting history" by
1549 editing old changelog entries.
1553 The format of the <file>debian/changelog</file> allows the
1554 package building tools to discover which version of the package
1555 is being built and find out other release-specific information.
1559 That format is a series of entries like this:
1561 <example compact="compact">
1562 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1564 [optional blank line(s), stripped]
1566 * <var>change details</var>
1567 <var>more change details</var>
1569 [blank line(s), included in output of dpkg-parsechangelog]
1571 * <var>even more change details</var>
1573 [optional blank line(s), stripped]
1575 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1580 <var>package</var> and <var>version</var> are the source
1581 package name and version number.
1585 <var>distribution(s)</var> lists the distributions where
1586 this version should be installed when it is uploaded - it
1587 is copied to the <tt>Distribution</tt> field in the
1588 <file>.changes</file> file. See <ref id="f-Distribution">.
1592 <var>urgency</var> is the value for the <tt>Urgency</tt>
1593 field in the <file>.changes</file> file for the upload
1594 (see <ref id="f-Urgency">). It is not possible to specify
1595 an urgency containing commas; commas are used to separate
1596 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1597 <prgn>dpkg</prgn> changelog format (though there is
1598 currently only one useful <var>keyword</var>,
1599 <tt>urgency</tt>).<footnote>
1600 Recognised urgency values are <tt>low</tt>,
1601 <tt>medium</tt>, <tt>high</tt> and <tt>emergency</tt>.
1602 They have an effect on how quickly a package will be
1603 considered for inclusion into the <tt>testing</tt>
1604 distribution, and give an indication of the importance
1605 of any fixes included in this upload.
1610 The change details may in fact be any series of lines
1611 starting with at least two spaces, but conventionally each
1612 change starts with an asterisk and a separating space and
1613 continuation lines are indented so as to bring them in
1614 line with the start of the text above. Blank lines may be
1615 used here to separate groups of changes, if desired.
1619 If this upload resolves bugs recorded in the Bug Tracking
1620 System (BTS), they may be automatically closed on the
1621 inclusion of this package into the Debian archive by
1622 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1623 in the change details.<footnote>
1624 To be precise, the string should match the following
1625 Perl regular expression:
1627 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1629 Then all of the bug numbers listed will be closed by the
1630 archive maintenance script (<prgn>katie</prgn>), or in
1631 the case of an NMU, marked as fixed.
1633 This information is conveyed via the <tt>Closes</tt> field
1634 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1638 The maintainer name and email address used in the changelog
1639 should be the details of the person uploading <em>this</em>
1640 version. They are <em>not</em> necessarily those of the
1641 usual package maintainer. The information here will be
1642 copied to the <tt>Changed-By</tt> field in the
1643 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1644 and then later used to send an acknowledgement when the
1645 upload has been installed.
1649 The <var>date</var> should be in RFC822 format<footnote>
1650 This is generated by the <prgn>822-date</prgn>
1652 </footnote>; it should include the time zone specified
1653 numerically, with the time zone name or abbreviation
1654 optionally present as a comment in parentheses.
1658 The first "title" line with the package name should start
1659 at the left hand margin; the "trailer" line with the
1660 maintainer and date details should be preceded by exactly
1661 one space. The maintainer details and the date must be
1662 separated by exactly two spaces.
1666 For more information on placement of the changelog files
1667 within binary packages, please see <ref id="changelogs">.
1670 <sect1><heading>Alternative changelog formats</heading>
1673 In non-experimental packages you must use a format for
1674 <file>debian/changelog</file> which is supported by the most
1675 recent released version of <prgn>dpkg</prgn>.
1679 It is possible to use a format different from the standard
1680 one by providing a changelog parser for the format you wish
1681 to use. The parser must have an API compatible with that
1682 expected by <prgn>dpkg-genchanges</prgn> and
1683 <prgn>dpkg-gencontrol</prgn>, and it must not interact with
1686 If there is general interest in the new format, you should
1687 contact the <package>dpkg</package> maintainer to have the
1688 parser script for it included in the <prgn>dpkg</prgn>
1689 package. (You will need to agree that the parser and its
1690 manpage may be distributed under the GNU GPL, just as the rest
1691 of <prgn>dpkg</prgn> is.)
1698 <heading>Error trapping in makefiles</heading>
1701 When <prgn>make</prgn> invokes a command in a makefile
1702 (including your package's upstream makefiles and
1703 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1704 means that <prgn>sh</prgn>'s usual bad error handling
1705 properties apply: if you include a miniature script as one
1706 of the commands in your makefile you'll find that if you
1707 don't do anything about it then errors are not detected
1708 and <prgn>make</prgn> will blithely continue after
1713 Every time you put more than one shell command (this
1714 includes using a loop) in a makefile command you
1715 must make sure that errors are trapped. For
1716 simple compound commands, such as changing directory and
1717 then running a program, using <tt>&&</tt> rather
1718 than semicolon as a command separator is sufficient. For
1719 more complex commands including most loops and
1720 conditionals you should include a separate <tt>set -e</tt>
1721 command at the start of every makefile command that's
1722 actually one of these miniature shell scripts.
1726 <sect id="timestamps">
1727 <heading>Time Stamps</heading>
1729 Maintainers should preserve the modification times of the
1730 upstream source files in a package, as far as is reasonably
1732 The rationale is that there is some information conveyed
1733 by knowing the age of the file, for example, you could
1734 recognize that some documentation is very old by looking
1735 at the modification time, so it would be nice if the
1736 modification time of the upstream source would be
1742 <sect id="restrictions">
1743 <heading>Restrictions on objects in source packages</heading>
1746 The source package may not contain any hard links<footnote>
1748 This is not currently detected when building source
1749 packages, but only when extracting
1753 Hard links may be permitted at some point in the
1754 future, but would require a fair amount of
1757 </footnote>, device special files, sockets or setuid or
1758 setgid files.<footnote>
1759 Setgid directories are allowed.
1765 <heading>Obsolete constructs and libraries</heading>
1768 The include file <tt><varargs.h></tt> is
1769 provided to support end-users compiling very old software;
1770 the library <tt>libtermcap</tt> is provided to support the
1771 execution of software which has been linked against it
1772 (either old programs or those such as Netscape which are
1773 only available in binary form).
1777 Debian packages should be patched to use
1778 <tt><stdarg.h></tt> and <tt>ncurses</tt>
1783 <sect id="debianrules">
1784 <heading>Main building script: <file>debian/rules</file></heading>
1787 This file must be an executable makefile, and contains the
1788 package-specific recipes for compiling the package and
1789 building binary package(s) from the source.
1793 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1794 so that it can be invoked by saying its name rather than
1795 invoking <prgn>make</prgn> explicitly.
1799 Since an interactive <file>debian/rules</file> script makes it
1800 impossible to auto-compile that package and also makes it
1801 hard for other people to reproduce the same binary
1802 package, all <em>required targets</em> MUST be
1803 non-interactive. At a minimum, required targets are the
1804 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1805 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1806 <em>binary-indep</em>, and <em>build</em>. It also follows
1807 that any target that these targets depend on must also be
1812 The targets are as follows (required unless stated otherwise):
1814 <tag><tt>build</tt></tag>
1817 The <tt>build</tt> target should perform all the
1818 configuration and compilation of the package.
1819 If a package has an interactive pre-build
1820 configuration routine, the Debianized source package
1821 must either be built after this has taken place (so
1822 that the binary package can be built without rerunning
1823 the configuration) or the configuration routine
1824 modified to become non-interactive. (The latter is
1825 preferable if there are architecture-specific features
1826 detected by the configuration routine.)
1830 For some packages, notably ones where the same
1831 source tree is compiled in different ways to produce
1832 two binary packages, the <tt>build</tt> target
1833 does not make much sense. For these packages it is
1834 good enough to provide two (or more) targets
1835 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1836 for each of the ways of building the package, and a
1837 <tt>build</tt> target that does nothing. The
1838 <tt>binary</tt> target will have to build the
1839 package in each of the possible ways and make the
1840 binary package out of each.
1844 The <tt>build</tt> target must not do anything
1845 that might require root privilege.
1849 The <tt>build</tt> target may need to run the
1850 <tt>clean</tt> target first - see below.
1854 When a package has a configuration and build routine
1855 which takes a long time, or when the makefiles are
1856 poorly designed, or when <tt>build</tt> needs to
1857 run <tt>clean</tt> first, it is a good idea to
1858 <tt>touch build</tt> when the build process is
1859 complete. This will ensure that if <tt>debian/rules
1860 build</tt> is run again it will not rebuild the whole
1862 Another common way to do this is for <tt>build</tt>
1863 to depend on <prgn>build-stamp</prgn> and to do
1864 nothing else, and for the <prgn>build-stamp</prgn>
1865 target to do the building and to <tt>touch
1866 build-stamp</tt> on completion. This is
1867 especially useful if the build routine creates a
1868 file or directory called <tt>build</tt>; in such a
1869 case, <tt>build</tt> will need to be listed as
1870 a phony target (i.e., as a dependency of the
1871 <tt>.PHONY</tt> target). See the documentation of
1872 <prgn>make</prgn> for more information on phony
1878 <tag><tt>build-arch</tt> (optional),
1879 <tt>build-indep</tt> (optional)
1883 A package may also provide both of the targets
1884 <tt>build-arch</tt> and <tt>build-indep</tt>.
1885 The <tt>build-arch</tt> target, if provided, should
1886 perform all the configuration and compilation required
1887 for producing all architecture-dependant binary packages
1888 (those packages for which the body of the
1889 <tt>Architecture</tt> field in <tt>debian/control</tt>
1890 is not <tt>all</tt>).
1891 Similarly, the <tt>build-indep</tt> target, if
1892 provided, should perform all the configuration and
1893 compilation required for producing all
1894 architecture-independent binary packages
1895 (those packages for which the body of the
1896 <tt>Architecture</tt> field in <tt>debian/control</tt>
1898 The <tt>build</tt> target should depend on those of the
1899 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1900 are provided in the rules file.
1904 If one or both of the targets <tt>build-arch</tt> and
1905 <tt>build-indep</tt> are not provided, then invoking
1906 <file>debian/rules</file> with one of the not-provided
1907 targets as arguments should produce a exit status code
1908 of 2. Usually this is provided automatically by make
1909 if the target is missing.
1913 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1914 must not do anything that might require root privilege.
1918 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1919 <tt>binary-indep</tt>
1923 The <tt>binary</tt> target must be all that is
1924 necessary for the user to build the binary package(s)
1925 produced from this source package. It is
1926 split into two parts: <prgn>binary-arch</prgn> builds
1927 the binary packages which are specific to a particular
1928 architecture, and <tt>binary-indep</tt> builds
1929 those which are not.
1932 <tt>binary</tt> may be (and commonly is) a target with
1933 no commands which simply depends on
1934 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1937 Both <tt>binary-*</tt> targets should depend on the
1938 <tt>build</tt> target, or on the appropriate
1939 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1940 provided, so that the package is built if it has not
1941 been already. It should then create the relevant
1942 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1943 make their control files and <prgn>dpkg-deb</prgn> to
1944 build them and place them in the parent of the top
1949 Both the <tt>binary-arch</tt> and
1950 <tt>binary-indep</tt> targets <em>must</em> exist.
1951 If one of them has nothing to do (which will always be
1952 the case if the source generates only a single binary
1953 package, whether architecture-dependent or not), it
1954 must still exist and must always succeed.
1958 The <tt>binary</tt> targets must be invoked as
1960 The <prgn>fakeroot</prgn> package often allows one
1961 to build a package correctly even without being
1967 <tag><tt>clean</tt></tag>
1970 This must undo any effects that the <tt>build</tt>
1971 and <tt>binary</tt> targets may have had, except
1972 that it should leave alone any output files created in
1973 the parent directory by a run of a <tt>binary</tt>
1978 If a <tt>build</tt> file is touched at the end of
1979 the <tt>build</tt> target, as suggested above, it
1980 should be removed as the first action that
1981 <tt>clean</tt> performs, so that running
1982 <tt>build</tt> again after an interrupted
1983 <tt>clean</tt> doesn't think that everything is
1988 The <tt>clean</tt> target may need to be
1989 invoked as root if <tt>binary</tt> has been
1990 invoked since the last <tt>clean</tt>, or if
1991 <tt>build</tt> has been invoked as root (since
1992 <tt>build</tt> may create directories, for
1997 <tag><tt>get-orig-source</tt> (optional)</tag>
2000 This target fetches the most recent version of the
2001 original source package from a canonical archive site
2002 (via FTP or WWW, for example), does any necessary
2003 rearrangement to turn it into the original source
2004 tar file format described below, and leaves it in the
2009 This target may be invoked in any directory, and
2010 should take care to clean up any temporary files it
2015 This target is optional, but providing it if
2016 possible is a good idea.
2022 The <tt>build</tt>, <tt>binary</tt> and
2023 <tt>clean</tt> targets must be invoked with the current
2024 directory being the package's top-level directory.
2029 Additional targets may exist in <file>debian/rules</file>,
2030 either as published or undocumented interfaces or for the
2031 package's internal use.
2035 The architectures we build on and build for are determined
2036 by <prgn>make</prgn> variables using the utility
2037 <qref id="pkg-dpkgarch"><prgn>dpkg-architecture</prgn></qref>.
2038 You can determine the
2039 Debian architecture and the GNU style architecture
2040 specification string for the build machine (the machine type
2041 we are building on) as well as for the host machine (the
2042 machine type we are building for). Here is a list of
2043 supported <prgn>make</prgn> variables:
2044 <list compact="compact">
2046 <tt>DEB_*_ARCH</tt> (the Debian architecture)
2049 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2050 specification string)
2053 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2054 <tt>DEB_*_GNU_TYPE</tt>)
2057 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2058 <tt>DEB_*_GNU_TYPE</tt>)
2060 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2061 the build machine or <tt>HOST</tt> for specification of the
2066 Backward compatibility can be provided in the rules file
2067 by setting the needed variables to suitable default
2068 values; please refer to the documentation of
2069 <prgn>dpkg-architecture</prgn> for details.
2073 It is important to understand that the <tt>DEB_*_ARCH</tt>
2074 string only determines which Debian architecture we are
2075 building on or for. It should not be used to get the CPU
2076 or system information; the GNU style variables should be
2081 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2082 <sect id="substvars">
2083 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2086 When <prgn>dpkg-gencontrol</prgn>,
2087 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2088 generate control files they perform variable substitutions
2089 on their output just before writing it. Variable
2090 substitutions have the form <tt>${<var>variable</var>}</tt>.
2091 The optional file <file>debian/substvars</file> contains
2092 variable substitutions to be used; variables can also be set
2093 directly from <file>debian/rules</file> using the <tt>-V</tt>
2094 option to the source packaging commands, and certain
2095 predefined variables are also available.
2099 The <file>debian/substvars</file> file is usually generated and
2100 modified dynamically by <file>debian/rules</file> targets, in
2101 which case it must be removed by the <tt>clean</tt> target.
2105 See <manref name="dpkg-source" section="1"> for full
2106 details about source variable substitutions, including the
2107 format of <file>debian/substvars</file>.</p>
2110 <sect id="debianfiles">
2111 <heading>Generated files list: <file>debian/files</file></heading>
2114 This file is not a permanent part of the source tree; it
2115 is used while building packages to record which files are
2116 being generated. <prgn>dpkg-genchanges</prgn> uses it
2117 when it generates a <file>.changes</file> file.
2121 It should not exist in a shipped source package, and so it
2122 (and any backup files or temporary files such as
2123 <file>files.new</file><footnote>
2124 <file>files.new</file> is used as a temporary file by
2125 <prgn>dpkg-gencontrol</prgn> and
2126 <prgn>dpkg-distaddfile</prgn> - they write a new
2127 version of <tt>files</tt> here before renaming it,
2128 to avoid leaving a corrupted copy if an error
2130 </footnote>) should be removed by the
2131 <tt>clean</tt> target. It may also be wise to
2132 ensure a fresh start by emptying or removing it at the
2133 start of the <tt>binary</tt> target.
2137 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2138 package, it adds an entry to <file>debian/files</file> for the
2139 <file>.deb</file> file that will be created when <tt>dpkg-deb
2140 --build</tt> is run for that binary package. So for most
2141 packages all that needs to be done with this file is to
2142 delete it in the <tt>clean</tt> target.
2146 If a package upload includes files besides the source
2147 package and any binary packages whose control files were
2148 made with <prgn>dpkg-gencontrol</prgn> then they should be
2149 placed in the parent of the package's top-level directory
2150 and <prgn>dpkg-distaddfile</prgn> should be called to add
2151 the file to the list in <file>debian/files</file>.</p>
2157 <chapt id="controlfields">
2158 <heading>Control files and their fields</heading>
2161 The package management system manipulates data represented in
2162 a common format, known as <em>control data</em>, stored in
2163 <em>control files</em>.
2164 Control files are used for source packages, binary packages and
2165 the <file>.changes</file> files which control the installation
2166 of uploaded files<footnote>
2167 <prgn>dpkg</prgn>'s internal databases are in a similar
2172 <sect id="controlsyntax">
2173 <heading>Syntax of control files</heading>
2176 A control file consists of one or more paragraphs of
2178 The paragraphs are also sometimes referred to as stanzas.
2180 The paragraphs are separated by blank lines. Some control
2181 files allow only one paragraph; others allow several, in
2182 which case each paragraph usually refers to a different
2183 package. (For example, in source packages, the first
2184 paragraph refers to the source package, and later paragraphs
2185 refer to binary packages generated from the source.)
2189 Each paragraph consists of a series of data fields; each
2190 field consists of the field name, followed by a colon and
2191 then the data/value associated with that field. It ends at
2192 the end of the line. Horizontal whitespace (spaces and
2193 tabs) may occur immediately before or after the value and is
2194 ignored there; it is conventional to put a single space
2195 after the colon. For example, a field might be:
2196 <example compact="compact">
2199 the field name is <tt>Package</tt> and the field value
2204 Some fields' values may span several lines; in this case
2205 each continuation line must start with a space or a tab.
2206 Any trailing spaces or tabs at the end of individual
2207 lines of a field value are ignored.
2211 Except where otherwise stated, only a single line of data is
2212 allowed and whitespace is not significant in a field body.
2213 Whitespace must not appear inside names (of packages,
2214 architectures, files or anything else) or version numbers,
2215 or between the characters of multi-character version
2220 Field names are not case-sensitive, but it is usual to
2221 capitalize the field names using mixed case as shown below.
2225 Blank lines, or lines consisting only of spaces and tabs,
2226 are not allowed within field values or between fields - that
2227 would mean a new paragraph.
2232 <sect id="sourcecontrolfiles">
2233 <heading>Source package control files -- <file>debian/control</file></heading>
2236 The <file>debian/control</file> file contains the most vital
2237 (and version-independent) information about the source package
2238 and about the binary packages it creates.
2242 The first paragraph of the control file contains information about
2243 the source package in general. The subsequent sets each describe a
2244 binary package that the source tree builds.
2248 The fields in the general paragraph (the first one, for the source
2251 <list compact="compact">
2252 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2253 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2254 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2255 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2256 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2257 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2262 The fields in the binary package paragraphs are:
2264 <list compact="compact">
2265 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2266 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2267 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2268 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2269 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2270 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2271 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2276 The syntax and semantics of the fields are described below.
2282 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2283 generate control files for binary packages (see below), by
2284 <prgn>dpkg-genchanges</prgn> to generate the
2285 <tt>.changes</tt> file to accompany the upload, and by
2286 <prgn>dpkg-source</prgn> when it creates the <file>.dsc</file>
2287 source control file as part of a source archive.
2291 The fields here may contain variable references - their
2292 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2293 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2294 when they generate output control files.
2295 See <ref id="substvars"> for details.
2300 <sect id="binarycontrolfiles">
2301 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2304 The <file>DEBIAN/control</file> file contains the most vital
2305 (and version-dependent) information about a binary package.
2309 The fields in this file are:
2311 <list compact="compact">
2312 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2313 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2314 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2315 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2316 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2317 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2318 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2319 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2320 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2321 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2322 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2327 <sect id="debiansourcecontrolfiles">
2328 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2331 This file contains a series of fields, identified and
2332 separated just like the fields in the control file of
2333 a binary package. The fields are listed below; their
2334 syntax is described above, in <ref id="pkg-controlfields">.
2336 <list compact="compact">
2337 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2338 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2339 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2340 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2341 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2342 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2343 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2344 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2349 The source package control file is generated by
2350 <prgn>dpkg-source</prgn> when it builds the source
2351 archive, from other files in the source package,
2352 described above. When unpacking, it is checked against
2353 the files and directories in the other parts of the
2359 <sect id="debianchangesfiles">
2360 <heading>Debian changes files -- <file>.changes</file></heading>
2363 The .changes files are used by the Debian archive maintenance
2364 software to process updates to packages. They contain one
2365 paragraph which contains information from the
2366 <tt>debian/control</tt> file and other data about the
2367 source package gathered via <tt>debian/changelog</tt>
2368 and <tt>debian/rules</tt>.
2372 The fields in this file are:
2374 <list compact="compact">
2375 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2376 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2377 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2378 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2379 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2380 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2381 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2382 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2383 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2384 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2385 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2386 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2387 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2388 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2393 <sect id="controlfieldslist">
2394 <heading>List of fields</heading>
2396 <sect1 id="f-Source">
2397 <heading><tt>Source</tt></heading>
2400 This field identifies the source package name.
2404 In a main source control information, a <file>.changes</file>
2405 or a <file>.dsc</file> file this may contain only the name
2406 of the source package.
2410 In the control file of a binary package it may be followed
2411 by a version number in parentheses<footnote>
2412 It is customary to leave a space after the package name
2413 if a version number is specified.
2415 This version number may be omitted (and is, by
2416 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2417 the <tt>Version</tt> field of the binary package in
2418 question. The field itself may be omitted from a binary
2419 package control file when the source package has the same
2420 name and version as the binary package.
2424 <sect1 id="f-Maintainer">
2425 <heading><tt>Maintainer</tt></heading>
2428 The package maintainer's name and email address. The name
2429 should come first, then the email address inside angle
2430 brackets <tt><></tt> (in RFC822 format).
2434 If the maintainer's name contains a full stop then the
2435 whole field will not work directly as an email address due
2436 to a misfeature in the syntax specified in RFC822; a
2437 program using this field as an address must check for this
2438 and correct the problem if necessary (for example by
2439 putting the name in round brackets and moving it to the
2440 end, and bringing the email address forward).
2444 <sect1 id="f-Changed-By">
2445 <heading><tt>Changed-By</tt></heading>
2448 The name and email address of the person who changed the
2449 said package. Usually the name of the maintainer.
2450 All the rules for the Maintainer field apply here, too.
2454 <sect1 id="f-Section">
2455 <heading><tt>Section</tt></heading>
2458 This field specifies an application area into which the package
2459 has been classified. See <ref id="subsections">.
2463 When it appears in the <file>debian/control</file> file,
2464 it gives the value for the subfield of the same name in
2465 the <tt>Files</tt> field of the <file>.changes</file> file.
2466 It also gives the default for the same field in the binary
2471 By default, <prgn>dpkg-gencontrol</prgn> does not include this
2472 field in the control file of a binary package - use the
2473 <tt>-is</tt> (or <tt>-isp</tt>) options to achieve this effect.
2477 <sect1 id="f-Priority">
2478 <heading><tt>Priority</tt></heading>
2481 This field represents how important that it is that the user
2482 have the package installed. See <ref id="priorities">.
2486 When it appears in the <file>debian/control</file> file,
2487 it gives the value for the subfield of the same name in
2488 the <tt>Files</tt> field of the <file>.changes</file> file.
2489 It also gives the default for the same field in the binary
2494 By default, <prgn>dpkg-gencontrol</prgn> does not include this
2495 field in the control file of a binary package - use the
2496 <tt>-ip</tt> (or <tt>-isp</tt>) options to achieve this effect.
2500 <sect1 id="f-Package">
2501 <heading><tt>Package</tt></heading>
2504 The name of the binary package.
2508 Package names must consist only of lower case letters
2509 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
2510 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
2511 They must be at least two characters long and must start
2512 with an alphanumeric character.
2516 <sect1 id="f-Architecture">
2517 <heading><tt>Architecture</tt></heading>
2520 This is the architecture string; it is a single word for
2521 the Debian architecture. The special value <tt>all</tt>
2522 indicates that the package is architecture-independent.
2526 In the main <file>debian/control</file> file in the source
2527 package, or in the source package control file
2528 <file>.dsc</file>, a list of architectures (separated by
2529 spaces) is also allowed, as is the special value
2530 <tt>any</tt>. A list indicates that the source will build
2531 an architecture-dependent package, and will only work
2532 correctly on the listed architectures. <tt>any</tt>
2533 indicates that though the source package isn't dependent
2534 on any particular architecture and should compile fine on
2535 any one, the binary package(s) produced are not
2536 architecture-independent but will instead be specific to
2537 whatever the current build architecture is.
2541 In a <file>.changes</file> file the <tt>Architecture</tt>
2542 field lists the architecture(s) of the package(s)
2543 currently being uploaded. This will be a list; if the
2544 source for the package is being uploaded too the special
2545 entry <tt>source</tt> is also present.
2549 See <ref id="debianrules"> for information how to get the
2550 architecture for the build process.
2554 <sect1 id="f-Essential">
2555 <heading><tt>Essential</tt></heading>
2558 This is a boolean field which may occur only in the
2559 control file of a binary package or in a per-package fields
2560 paragraph of a main source control data file.
2564 If set to <tt>yes</tt> then the package management system
2565 will refuse to remove the package (upgrading and replacing
2566 it is still possible). The other possible value is <tt>no</tt>,
2567 which is the same as not having the field at all.
2572 <heading>Package interrelationship fields:
2573 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2574 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Conflicts</tt>,
2575 <tt>Provides</tt>, <tt>Replaces</tt>
2579 These fields describe the package's relationships with
2580 other packages. Their syntax and semantics are described
2581 in <ref id="relationships">.</p>
2584 <sect1 id="f-Standards-Version">
2585 <heading><tt>Standards-Version</tt></heading>
2588 The most recent version of the standards (the policy
2589 manual and associated texts) with which the package
2594 The version number has four components: major and minor
2595 version number and major and minor patch level. When the
2596 standards change in a way that requires every package to
2597 change the major number will be changed. Significant
2598 changes that will require work in many packages will be
2599 signaled by a change to the minor number. The major patch
2600 level will be changed for any change to the meaning of the
2601 standards, however small; the minor patch level will be
2602 changed when only cosmetic, typographical or other edits
2603 are made which neither change the meaning of the document
2604 nor affect the contents of packages.
2608 Thus only the first three components of the policy version
2609 are significant in the <em>Standards-Version</em> control
2610 field, and so either these three components or the all
2611 four components may be specified.<footnote>
2612 In the past, people specified the full version number
2613 in the Standards-Version field, for example "2.3.0.0".
2614 Since minor patch-level changes don't introduce new
2615 policy, it was thought it would be better to relax
2616 policy and only require the first 3 components to be
2617 specified, in this example "2.3.0". All four
2618 components may still be used if someone wishes to do so.
2624 <sect1 id="f-Version">
2625 <heading><tt>Version</tt></heading>
2628 The version number of a package. The format is:
2629 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2633 The three components here are:
2635 <tag><var>epoch</var></tag>
2638 This is a single (generally small) unsigned integer. It
2639 may be omitted, in which case zero is assumed. If it is
2640 omitted then the <var>upstream_version</var> may not
2645 It is provided to allow mistakes in the version numbers
2646 of older versions of a package, and also a package's
2647 previous version numbering schemes, to be left behind.
2651 <tag><var>upstream_version</var></tag>
2654 This is the main part of the version number. It is
2655 usually the version number of the original ("upstream")
2656 package from which the <file>.deb</file> file has been made,
2657 if this is applicable. Usually this will be in the same
2658 format as that specified by the upstream author(s);
2659 however, it may need to be reformatted to fit into the
2660 package management system's format and comparison
2665 The comparison behavior of the package management system
2666 with respect to the <var>upstream_version</var> is
2667 described below. The <var>upstream_version</var>
2668 portion of the version number is mandatory.
2672 The <var>upstream_version</var> may contain only
2673 alphanumerics<footnote>
2674 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2676 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2677 <tt>:</tt> (full stop, plus, hyphen, colon) and should
2678 start with a digit. If there is no
2679 <var>debian_revision</var> then hyphens are not allowed;
2680 if there is no <var>epoch</var> then colons are not
2685 <tag><var>debian_revision</var></tag>
2688 This part of the version number specifies the version of
2689 the Debian package based on the upstream version. It
2690 may contain only alphanumerics and the characters
2691 <tt>+</tt> and <tt>.</tt> (plus and full stop) and is
2692 compared in the same way as the
2693 <var>upstream_version</var> is.
2697 It is optional; if it isn't present then the
2698 <var>upstream_version</var> may not contain a hyphen.
2699 This format represents the case where a piece of
2700 software was written specifically to be turned into a
2701 Debian package, and so there is only one "debianization"
2702 of it and therefore no revision indication is required.
2706 It is conventional to restart the
2707 <var>debian_revision</var> at <tt>1</tt> each time the
2708 <var>upstream_version</var> is increased.
2712 The package management system will break the version
2713 number apart at the last hyphen in the string (if there
2714 is one) to determine the <var>upstream_version</var> and
2715 <var>debian_revision</var>. The absence of a
2716 <var>debian_revision</var> compares earlier than the
2717 presence of one (but note that the
2718 <var>debian_revision</var> is the least significant part
2719 of the version number).
2726 The <var>upstream_version</var> and <var>debian_revision</var>
2727 parts are compared by the package management system using the
2732 The strings are compared from left to right.
2736 First the initial part of each string consisting entirely of
2737 non-digit characters is determined. These two parts (one of
2738 which may be empty) are compared lexically. If a difference
2739 is found it is returned. The lexical comparison is a
2740 comparison of ASCII values modified so that all the letters
2741 sort earlier than all the non-letters.
2745 Then the initial part of the remainder of each string which
2746 consists entirely of digit characters is determined. The
2747 numerical values of these two parts are compared, and any
2748 difference found is returned as the result of the comparison.
2749 For these purposes an empty string (which can only occur at
2750 the end of one or both version strings being compared) counts
2755 These two steps (comparing and removing initial non-digit
2756 strings and initial digit strings) are repeated until a
2757 difference is found or both strings are exhausted.
2761 Note that the purpose of epochs is to allow us to leave behind
2762 mistakes in version numbering, and to cope with situations
2763 where the version numbering scheme changes. It is
2764 <em>not</em> intended to cope with version numbers containing
2765 strings of letters which the package management system cannot
2766 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
2767 silly orderings (the author of this manual has heard of a
2768 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
2769 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
2770 <tt>2</tt> and so forth).
2774 <sect1 id="f-Description">
2775 <heading><tt>Description</tt></heading>
2778 In a source or binary control file, the <tt>Description</tt>
2779 field contains a description of the binary package, consisting
2780 of two parts, the synopsis or the short description, and the
2781 long description. The field's format is as follows:
2786 Description: <single line synopsis>
2787 <extended description over several lines>
2792 The lines in the extended description can have these formats:
2798 Those starting with a single space are part of a paragraph.
2799 Successive lines of this form will be word-wrapped when
2800 displayed. The leading space will usually be stripped off.
2804 Those starting with two or more spaces. These will be
2805 displayed verbatim. If the display cannot be panned
2806 horizontally, the displaying program will linewrap them "hard"
2807 (i.e., without taking account of word breaks). If it can they
2808 will be allowed to trail off to the right. None, one or two
2809 initial spaces may be deleted, but the number of spaces
2810 deleted from each line will be the same (so that you can have
2811 indenting work correctly, for example).
2815 Those containing a single space followed by a single full stop
2816 character. These are rendered as blank lines. This is the
2817 <em>only</em> way to get a blank line<footnote>
2818 Completely empty lines will not be rendered as blank lines.
2819 Instead, they will cause the parser to think you're starting
2820 a whole new record in the control file, and will therefore
2821 likely abort with an error.
2826 Those containing a space, a full stop and some more characters.
2827 These are for future expansion. Do not use them.
2833 Do not use tab characters. Their effect is not predictable.
2837 See <ref id="descriptions"> for further information on this.
2841 In a <file>.changes</file> file, the <tt>Description</tt> field
2842 contains a summary of the descriptions for the packages being
2847 The part of the field before the first newline is empty;
2848 thereafter each line has the name of a binary package and
2849 the summary description line from that binary package.
2850 Each line is indented by one space.
2855 <sect1 id="f-Distribution">
2856 <heading><tt>Distribution</tt></heading>
2859 In a <file>.changes</file> file or parsed changelog output
2860 this contains the (space-separated) name(s) of the
2861 distribution(s) where this version of the package should
2862 be installed. Valid distributions are determined by the
2863 archive maintainers.<footnote>
2864 Current distribution names are:
2865 <taglist compact="compact">
2866 <tag><em>stable</em></tag>
2868 This is the current "released" version of Debian
2869 GNU/Linux. Once the distribution is
2870 <em>stable</em> only security fixes and other
2871 major bug fixes are allowed. When changes are
2872 made to this distribution, the release number is
2873 increased (for example: 2.2r1 becomes 2.2r2 then
2877 <tag><em>unstable</em></tag>
2879 This distribution value refers to the
2880 <em>developmental</em> part of the Debian
2881 distribution tree. New packages, new upstream
2882 versions of packages and bug fixes go into the
2883 <em>unstable</em> directory tree. Download from
2884 this distribution at your own risk.
2887 <tag><em>testing</em></tag>
2889 This distribution value refers to the
2890 <em>testing</em> part of the Debian distribution
2891 tree. It receives its packages from the
2892 unstable distribution after a short time lag to
2893 ensure that there are no major issues with the
2894 unstable packages. It is less prone to breakage
2895 than unstable, but still risky. It is not
2896 possible to upload packages directly to
2900 <tag><em>frozen</em></tag>
2902 From time to time, the <em>testing</em>
2903 distribution enters a state of "code-freeze" in
2904 anticipation of release as a <em>stable</em>
2905 version. During this period of testing only
2906 fixes for existing or newly-discovered bugs will
2907 be allowed. The exact details of this stage are
2908 determined by the Release Manager.
2911 <tag><em>experimental</em></tag>
2913 The packages with this distribution value are
2914 deemed by their maintainers to be high
2915 risk. Oftentimes they represent early beta or
2916 developmental packages from various sources that
2917 the maintainers want people to try, but are not
2918 ready to be a part of the other parts of the
2919 Debian distribution tree. Download at your own
2925 You should list <em>all</em> distributions that the
2926 package should be installed into.
2930 More information is available in the Debian Developer's
2931 Reference, section "The Debian archive".
2938 <heading><tt>Date</tt></heading>
2941 This field includes the date the package was built or last edited.
2945 The value of this field is usually extracted from the
2946 <file>debian/changelog</file> file - see
2947 <ref id="dpkgchangelog">).
2951 <sect1 id="f-Format">
2952 <heading><tt>Format</tt></heading>
2955 This field specifies a format revision for the file.
2956 The most current format described in the Policy Manual
2957 is version <strong>1.5</strong>. The syntax of the
2958 format value is the same as that of a package version
2959 number except that no epoch or Debian revision is allowed
2960 - see <ref id="f-Version">.
2964 <sect1 id="f-Urgency">
2965 <heading><tt>Urgency</tt></heading>
2968 This is a description of how important it is to upgrade to
2969 this version from previous ones. It consists of a single
2970 keyword usually taking one of the values <tt>low</tt>,
2971 <tt>medium</tt> or <tt>high</tt> (not case-sensitive)
2972 followed by an optional commentary (separated by a space)
2973 which is usually in parentheses. For example:
2976 Urgency: low (HIGH for users of diversions)
2982 The value of this field is usually extracted from the
2983 <file>debian/changelog</file> file - see
2984 <ref id="dpkgchangelog">.
2988 <sect1 id="f-Changes">
2989 <heading><tt>Changes</tt></heading>
2992 This field contains the human-readable changes data, describing
2993 the differences between the last version and the current one.
2997 There should be nothing in this field before the first
2998 newline; all the subsequent lines must be indented by at
2999 least one space; blank lines must be represented by a line
3000 consiting only of a space and a full stop.
3004 The value of this field is usually extracted from the
3005 <file>debian/changelog</file> file - see
3006 <ref id="dpkgchangelog">).
3010 Each version's change information should be preceded by a
3011 "title" line giving at least the version, distribution(s)
3012 and urgency, in a human-readable way.
3016 If data from several versions is being returned the entry
3017 for the most recent version should be returned first, and
3018 entries should be separated by the representation of a
3019 blank line (the "title" line may also be followed by the
3020 representation of blank line).
3024 <sect1 id="f-Binary">
3025 <heading><tt>Binary</tt></heading>
3028 This field is a list of binary packages.
3032 When it appears in the <file>.dsc</file> file it is the list
3033 of binary packages which a source package can produce. It
3034 does not necessarily produce all of these binary packages
3035 for every architecture. The source control file doesn't
3036 contain details of which architectures are appropriate for
3037 which of the binary packages.
3041 When it appears in a <file>.changes</file> file it lists the
3042 names of the binary packages actually being uploaded.
3046 The syntax is a list of binary packages separated by
3048 A space after each comma is conventional.
3049 </footnote>. Currently the packages must be separated using
3050 only spaces in the <file>.changes</file> file.
3054 <sect1 id="f-Installed-Size">
3055 <heading><tt>Installed-Size</tt></heading>
3058 This field appears in the control files of binary
3059 packages, and in the <file>Packages</file> files. It gives
3060 the total amount of disk space required to install the
3065 The disk space is represented in kilobytes as a simple
3070 <sect1 id="f-Files">
3071 <heading><tt>Files</tt></heading>
3074 This field contains a list of files with information about
3075 each one. The exact information and syntax varies with
3076 the context. In all cases the part of the field
3077 contents on the same line as the field name is empty. The
3078 remainder of the field is one line per file, each line
3079 being indented by one space and containing a number of
3080 sub-fields separated by spaces.
3084 In the <file>.dsc</file> file, each line contains the MD5
3085 checksum, size and filename of the tar file and (if applicable)
3086 diff file which make up the remainder of the source
3088 That is, the parts which are not the <tt>.dsc</tt>.
3090 The exact forms of the filenames are described
3091 in <ref id="pkg-sourcearchives">.
3095 In the <file>.changes</file> file this contains one line per
3096 file being uploaded. Each line contains the MD5 checksum,
3097 size, section and priority and the filename.
3098 The <qref id="f-Section">section</qref>
3099 and <qref id="f-Priority">priority</qref>
3100 are the values of the corresponding fields in
3101 the main source control file. If no section or priority is
3102 specified then <tt>-</tt> should be used, though section
3103 and priority values must be specified for new packages to
3104 be installed properly.
3108 The special value <tt>byhand</tt> for the section in a
3109 <tt>.changes</tt> file indicates that the file in question
3110 is not an ordinary package file and must by installed by
3111 hand by the distribution maintainers. If the section is
3112 <tt>byhand</tt> the priority should be <tt>-</tt>.
3116 If a new Debian revision of a package is being shipped and
3117 no new original source archive is being distributed the
3118 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3119 entry for the original source archive
3120 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
3121 but the <file>.changes</file> file should leave it out. In
3122 this case the original source archive on the distribution
3123 site must match exactly, byte-for-byte, the original
3124 source archive which was used to generate the
3125 <file>.dsc</file> file and diff which are being uploaded.</p>
3128 <sect1 id="f-Closes">
3129 <heading><tt>Closes</tt></heading>
3132 A space-separated list of bug report numbers that the upload
3133 governed by the .changes file closes.
3140 <heading>User-defined fields</heading>
3143 Additional user-defined fields may be added to the
3144 source package control file. Such fields will be
3145 ignored, and not copied to (for example) binary or
3146 source package control files or upload control files.
3150 If you wish to add additional unsupported fields to
3151 these output files you should use the mechanism
3156 Fields in the main source control information file with
3157 names starting <tt>X</tt>, followed by one or more of
3158 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3159 be copied to the output files. Only the part of the
3160 field name after the hyphen will be used in the output
3161 file. Where the letter <tt>B</tt> is used the field
3162 will appear in binary package control files, where the
3163 letter <tt>S</tt> is used in source package control
3164 files and where <tt>C</tt> is used in upload control
3165 (<tt>.changes</tt>) files.
3169 For example, if the main source information control file
3172 XBS-Comment: I stand between the candle and the star.
3174 then the binary and source package control files will contain the
3177 Comment: I stand between the candle and the star.
3186 <chapt id="maintainerscripts">
3187 <heading>Package maintainer scripts and installation procedure</heading>
3190 <heading>Introduction to package maintainer scripts</heading>
3193 It is possible to supply scripts as part of a package which
3194 the package management system will run for you when your
3195 package is installed, upgraded or removed.
3199 These scripts are the files <prgn>preinst</prgn>,
3200 <prgn>postinst</prgn>, <prgn>prerm</prgn> and <prgn>postrm</prgn> in the
3201 control area of the package. They must be proper executable
3202 files; if they are scripts (which is recommended), they must
3203 start with the usual <tt>#!</tt> convention. They should be
3204 readable and executable by anyone, and not world-writable.
3208 The package management system looks at the exit status from
3209 these scripts. It is important that they exit with a
3210 non-zero status if there is an error, so that the package
3211 management system can stop its processing. For shell
3212 scripts this means that you <em>almost always</em> need to
3213 use <tt>set -e</tt> (this is usually true when writing shell
3214 scripts, in fact). It is also important, of course, that
3215 they don't exit with a non-zero status if everything went
3220 When a package is upgraded a combination of the scripts from
3221 the old and new packages is called during the upgrade
3222 procedure. If your scripts are going to be at all
3223 complicated you need to be aware of this, and may need to
3224 check the arguments to your scripts.
3228 Broadly speaking the <prgn>preinst</prgn> is called before
3229 (a particular version of) a package is installed, and the
3230 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3231 before (a version of) a package is removed and the
3232 <prgn>postrm</prgn> afterwards.
3236 Programs called from maintainer scripts should not normally
3237 have a path prepended to them. Before installation is
3238 started, the package management system checks to see if the
3239 programs <prgn>ldconfig</prgn>,
3240 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3241 and <prgn>update-rc.d</prgn> can be found via the
3242 <tt>PATH</tt> environment variable. Those programs, and any
3243 other program that one would expect to be on the
3244 <tt>PATH</tt>, should thus be invoked without an absolute
3245 pathname. Maintainer scripts should also not reset the
3246 <tt>PATH</tt>, though they might choose to modify it by
3247 prepending or appending package-specific directories. These
3248 considerations really apply to all shell scripts.</p>
3251 <sect id="idempotency">
3252 <heading>Maintainer scripts Idempotency</heading>
3255 It is necessary for the error recovery procedures that the
3256 scripts be idempotent. This means that if it is run
3257 successfully, and then it is called again, it doesn't bomb
3258 out or cause any harm, but just ensures that everything is
3259 the way it ought to be. If the first call failed, or
3260 aborted half way through for some reason, the second call
3261 should merely do the things that were left undone the first
3262 time, if any, and exit with a success status if everything
3264 This is so that if an error occurs, the user interrupts
3265 <prgn>dpkg</prgn> or some other unforeseen circumstance
3266 happens you don't leave the user with a badly-broken
3267 package when <prgn>dpkg</prgn> attempts to repeat the
3273 <sect id="controllingterminal">
3274 <heading>Controlling terminal for maintainer scripts</heading>
3277 The maintainer scripts are guaranteed to run with a
3278 controlling terminal and can interact with the user.
3279 If they need to prompt for passwords, do full-screen
3280 interaction or something similar you should do these
3281 things to and from <file>/dev/tty</file>, since
3282 <prgn>dpkg</prgn> will at some point redirect scripts'
3283 standard input and output so that it can log the
3284 installation process. Likewise, because these scripts
3285 may be executed with standard output redirected into a
3286 pipe for logging purposes, Perl scripts should set
3287 unbuffered output by setting <tt>$|=1</tt> so that the
3288 output is printed immediately rather than being
3293 Each script should return a zero exit status for
3294 success, or a nonzero one for failure.
3298 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3303 <list compact="compact">
3305 <var>new-preinst</var> <tt>install</tt>
3308 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3311 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3314 <var>old-preinst</var> <tt>abort-upgrade</tt>
3315 <var>new-version</var>
3320 <list compact="compact">
3322 <var>postinst</var> <tt>configure</tt>
3323 <var>most-recently-configured-version</var>
3326 <var>old-postinst</var> <tt>abort-upgrade</tt>
3327 <var>new-version</var>
3330 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3331 <tt>in-favour</tt> <var>package</var>
3332 <var>new-version</var>
3335 <var>deconfigured's-postinst</var>
3336 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3337 <var>failed-install-package</var> <var>version</var>
3338 <tt>removing</tt> <var>conflicting-package</var>
3344 <list compact="compact">
3346 <var>prerm</var> <tt>remove</tt>
3349 <var>old-prerm</var> <tt>upgrade</tt>
3350 <var>new-version</var>
3353 <var>new-prerm</var> <tt>failed-upgrade</tt>
3354 <var>old-version</var>
3357 <var>conflictor's-prerm</var> <tt>remove</tt>
3358 <tt>in-favour</tt> <var>package</var>
3359 <var>new-version</var>
3362 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3363 <tt>in-favour</tt> <var>package-being-installed</var>
3364 <var>version</var> <tt>removing</tt>
3365 <var>conflicting-package</var>
3371 <list compact="compact">
3373 <var>postrm</var> <tt>remove</tt>
3376 <var>postrm</var> <tt>purge</tt>
3379 <var>old-postrm</var> <tt>upgrade</tt>
3380 <var>new-version</var>
3383 <var>new-postrm</var> <tt>failed-upgrade</tt>
3384 <var>old-version</var>
3387 <var>new-postrm</var> <tt>abort-install</tt>
3390 <var>new-postrm</var> <tt>abort-install</tt>
3391 <var>old-version</var>
3394 <var>new-postrm</var> <tt>abort-upgrade</tt>
3395 <var>old-version</var>
3398 <var>disappearer's-postrm</var> <tt>disappear</tt>
3399 <var>overwriter</var>
3400 <var>overwriter-version</var>
3406 <sect id="unpackphase">
3407 <heading>Details of unpack phase of installation or upgrade</heading>
3410 The procedure on installation/upgrade/overwrite/disappear
3411 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3412 stage of <tt>dpkg --install</tt>) is as follows. In each
3413 case, if a major error occurs (unless listed below) the
3414 actions are, in general, run backwards - this means that the
3415 maintainer scripts are run with different arguments in
3416 reverse order. These are the "error unwind" calls listed
3423 If a version of the package is already installed, call
3424 <example compact="compact">
3425 <var>old-prerm</var> upgrade <var>new-version</var>
3429 If the script runs but exits with a non-zero
3430 exit status, <prgn>dpkg</prgn> will attempt:
3431 <example compact="compact">
3432 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3434 Error unwind, for both the above cases:
3435 <example compact="compact">
3436 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3443 If a "conflicting" package is being removed at the same time:
3446 If any packages depended on that conflicting
3447 package and <tt>--auto-deconfigure</tt> is
3448 specified, call, for each such package:
3449 <example compact="compact">
3450 <var>deconfigured's-prerm</var> deconfigure \
3451 in-favour <var>package-being-installed</var> <var>version</var> \
3452 removing <var>conflicting-package</var> <var>version</var>
3455 <example compact="compact">
3456 <var>deconfigured's-postinst</var> abort-deconfigure \
3457 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3458 removing <var>conflicting-package</var> <var>version</var>
3460 The deconfigured packages are marked as
3461 requiring configuration, so that if
3462 <tt>--install</tt> is used they will be
3463 configured again if possible.
3466 To prepare for removal of the conflicting package, call:
3467 <example compact="compact">
3468 <var>conflictor's-prerm</var> remove \
3469 in-favour <var>package</var> <var>new-version</var>
3472 <example compact="compact">
3473 <var>conflictor's-postinst</var> abort-remove \
3474 in-favour <var>package</var> <var>new-version</var>
3483 If the package is being upgraded, call:
3484 <example compact="compact">
3485 <var>new-preinst</var> upgrade <var>old-version</var>
3489 Otherwise, if the package had some configuration
3490 files from a previous version installed (i.e., it
3491 is in the "configuration files only" state):
3492 <example compact="compact">
3493 <var>new-preinst</var> install <var>old-version</var>
3497 Otherwise (i.e., the package was completely purged):
3498 <example compact="compact">
3499 <var>new-preinst</var> install
3501 Error unwind actions, respectively:
3502 <example compact="compact">
3503 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3504 <var>new-postrm</var> abort-install <var>old-version</var>
3505 <var>new-postrm</var> abort-install
3513 The new package's files are unpacked, overwriting any
3514 that may be on the system already, for example any
3515 from the old version of the same package or from
3516 another package. Backups of the old files are kept
3517 temporarily, and if anything goes wrong the package
3518 management system will attempt to put them back as
3519 part of the error unwind.
3523 It is an error for a package to contain files which
3524 are on the system in another package, unless
3525 <tt>Replaces</tt> is used (see <ref id="replaces">).
3527 The following paragraph is not currently the case:
3528 Currently the <tt>- - force-overwrite</tt> flag is
3529 enabled, downgrading it to a warning, but this may not
3535 It is a more serious error for a package to contain a
3536 plain file or other kind of non-directory where another
3537 package has a directory (again, unless
3538 <tt>Replaces</tt> is used). This error can be
3539 overridden if desired using
3540 <tt>--force-overwrite-dir</tt>, but this is not
3545 Packages which overwrite each other's files produce
3546 behavior which, though deterministic, is hard for the
3547 system administrator to understand. It can easily
3548 lead to "missing" programs if, for example, a package
3549 is installed which overwrites a file from another
3550 package, and is then removed again.<footnote>
3551 Part of the problem is due to what is arguably a
3552 bug in <prgn>dpkg</prgn>.
3557 A directory will never be replaced by a symbolic link
3558 to a directory or vice versa; instead, the existing
3559 state (symlink or not) will be left alone and
3560 <prgn>dpkg</prgn> will follow the symlink if there is
3569 If the package is being upgraded, call
3570 <example compact="compact">
3571 <var>old-postrm</var> upgrade <var>new-version</var>
3575 If this fails, <prgn>dpkg</prgn> will attempt:
3576 <example compact="compact">
3577 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3579 Error unwind, for both cases:
3580 <example compact="compact">
3581 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3588 This is the point of no return - if
3589 <prgn>dpkg</prgn> gets this far, it won't back off
3590 past this point if an error occurs. This will
3591 leave the package in a fairly bad state, which
3592 will require a successful re-installation to clear
3593 up, but it's when <prgn>dpkg</prgn> starts doing
3594 things that are irreversible.
3599 Any files which were in the old version of the package
3600 but not in the new are removed.
3604 The new file list replaces the old.
3608 The new maintainer scripts replace the old.
3612 Any packages all of whose files have been overwritten
3613 during the installation, and which aren't required for
3614 dependencies, are considered to have been removed.
3615 For each such package
3618 <prgn>dpkg</prgn> calls:
3619 <example compact="compact">
3620 <var>disappearer's-postrm</var> disappear \
3621 <var>overwriter</var> <var>overwriter-version</var>
3625 The package's maintainer scripts are removed.
3628 It is noted in the status database as being in a
3629 sane state, namely not installed (any conffiles
3630 it may have are ignored, rather than being
3631 removed by <prgn>dpkg</prgn>). Note that
3632 disappearing packages do not have their prerm
3633 called, because <prgn>dpkg</prgn> doesn't know
3634 in advance that the package is going to
3641 Any files in the package we're unpacking that are also
3642 listed in the file lists of other packages are removed
3643 from those lists. (This will lobotomize the file list
3644 of the "conflicting" package if there is one.)
3648 The backup files made during installation, above, are
3654 The new package's status is now sane, and recorded as
3659 Here is another point of no return - if the
3660 conflicting package's removal fails we do not unwind
3661 the rest of the installation; the conflicting package
3662 is left in a half-removed limbo.
3667 If there was a conflicting package we go and do the
3668 removal actions (described below), starting with the
3669 removal of the conflicting package's files (any that
3670 are also in the package being installed have already
3671 been removed from the conflicting package's file list,
3672 and so do not get removed now).
3678 <sect id="configdetails"><heading>Details of configuration</heading>
3681 When we configure a package (this happens with <tt>dpkg
3682 --install</tt> and <tt>dpkg --configure</tt>), we first
3683 update any <tt>conffile</tt>s and then call:
3684 <example compact="compact">
3685 <var>postinst</var> configure <var>most-recently-configured-version</var>
3690 No attempt is made to unwind after errors during
3695 If there is no most recently configured version
3696 <prgn>dpkg</prgn> will pass a null argument; older versions
3697 of dpkg may pass <tt><unknown></tt> (including the
3698 angle brackets) in this case. Even older ones do not pass a
3699 second argument at all, under any circumstances.
3703 <sect id="removedetails"><heading>Details of removal and/or
3704 configuration purging</heading>
3709 <example compact="compact">
3710 <var>prerm</var> remove
3714 The package's files are removed (except <tt>conffile</tt>s).
3717 <example compact="compact">
3718 <var>postrm</var> remove
3723 All the maintainer scripts except the <prgn>postrm</prgn>
3728 If we aren't purging the package we stop here. Note
3729 that packages which have no <prgn>postrm</prgn> and no
3730 <tt>conffile</tt>s are automatically purged when
3731 removed, as there is no difference except for the
3732 <prgn>dpkg</prgn> status.
3736 The <tt>conffile</tt>s and any backup files
3737 (<tt>~</tt>-files, <tt>#*#</tt> files,
3738 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
3742 <example compact="compact">
3743 <var>postrm</var> purge
3747 The package's file list is removed.
3751 No attempt is made to unwind after errors during
3758 <chapt id="relationships">
3759 <heading>Declaring relationships between packages</heading>
3761 <sect id="depsyntax">
3762 <heading>Syntax of relationship fields</heading>
3765 These fields all have a uniform syntax. They are a list of
3766 package names separated by commas.
3770 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3771 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3772 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3773 control file fields of the package, which declare
3774 dependencies on other packages, the package names listed may
3775 also include lists of alternative package names, separated
3776 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
3777 if any one of the alternative packages is installed, that
3778 part of the dependency is considered to be satisfied.
3782 All of the fields except for <tt>Provides</tt> may restrict
3783 their applicability to particular versions of each named
3784 package. This is done in parentheses after each individual
3785 package name; the parentheses should contain a relation from
3786 the list below followed by a version number, in the format
3787 described in <ref id="f-Version">.
3791 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3792 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3793 strictly earlier, earlier or equal, exactly equal, later or
3794 equal and strictly later, respectively. The deprecated
3795 forms <tt><</tt> and <tt>></tt> were used to mean
3796 earlier/later or equal, rather than strictly earlier/later,
3797 so they should not appear in new packages (though
3798 <prgn>dpkg</prgn> still supports them).
3802 Whitespace may appear at any point in the version
3803 specification subject to the rules in <ref
3804 id="controlsyntax">, and must appear where it's necessary to
3805 disambiguate; it is not otherwise significant. For
3806 consistency and in case of future changes to
3807 <prgn>dpkg</prgn> it is recommended that a single space be
3808 used after a version relationship and before a version
3809 number; it is also conventional to put a single space after
3810 each comma, on either side of each vertical bar, and before
3811 each open parenthesis.
3815 For example, a list of dependencies might appear as:
3816 <example compact="compact">
3819 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
3824 All fields that specify build-time relationships
3825 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3826 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3827 may be restricted to a certain set of architectures. This
3828 is indicated in brackets after each individual package name and
3829 the optional version specification. The brackets enclose a
3830 list of Debian architecture names separated by whitespace.
3831 Exclamation marks may be prepended to each of the names.
3832 (It is not permitted for some names to be prepended with
3833 exclamation marks and others not.) If the current Debian
3834 host architecture is not in this list and there are no
3835 exclamation marks in the list, or it is in the list with a
3836 prepended exclamation mark, the package name and the
3837 associated version specification are ignored completely for
3838 the purposes of defining the relationships.
3843 <example compact="compact">
3845 Build-Depends-Indep: texinfo
3846 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3847 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3852 Note that the binary package relationship fields such as
3853 <tt>Depends</tt> appear in one of the binary package
3854 sections of the control file, whereas the build-time
3855 relationships such as <tt>Build-Depends</tt> appear in the
3856 source package section of the control file (which is the
3861 <sect id="binarydeps">
3862 <heading>Binary Dependencies - <tt>Depends</tt>,
3863 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3864 <tt>Pre-Depends</tt>
3868 Packages can declare in their control file that they have
3869 certain relationships to other packages - for example, that
3870 they may not be installed at the same time as certain other
3871 packages, and/or that they depend on the presence of others.
3875 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
3876 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt> and
3877 <tt>Conflicts</tt> control file fields.
3881 These six fields are used to declare a dependency
3882 relationship by one package on another. Except for
3883 <tt>Enhances</tt>, they appear in the depending (binary)
3884 package's control file. (<tt>Enhances</tt> appears in the
3885 recommending package's control file.)
3889 A <tt>Depends</tt> field takes effect <em>only</em> when a
3890 package is to be configured. It does not prevent a package
3891 being on the system in an unconfigured state while its
3892 dependencies are unsatisfied, and it is possible to replace
3893 a package whose dependencies are satisfied and which is
3894 properly installed with a different version whose
3895 dependencies are not and cannot be satisfied; when this is
3896 done the depending package will be left unconfigured (since
3897 attempts to configure it will give errors) and will not
3898 function properly. If it is necessary, a
3899 <tt>Pre-Depends</tt> field can be used, which has a partial
3900 effect even when a package is being unpacked, as explained
3901 in detail below. (The other three dependency fields,
3902 <tt>Recommends</tt>, <tt>Suggests</tt> and
3903 <tt>Enhances</tt>, are only used by the various front-ends
3904 to <prgn>dpkg</prgn> such as <prgn>dselect</prgn>.)
3908 For this reason packages in an installation run are usually
3909 all unpacked first and all configured later; this gives
3910 later versions of packages with dependencies on later
3911 versions of other packages the opportunity to have their
3912 dependencies satisfied.
3916 The <tt>Depends</tt> field thus allows package maintainers
3917 to impose an order in which packages should be configured.
3921 The meaning of the five dependency fields is as follows:
3923 <tag><tt>Depends</tt></tag>
3926 This declares an absolute dependency. A package will
3927 not be configured unless all of the packages listed in
3928 its <tt>Depends</tt> field have been correctly
3933 The <tt>Depends</tt> field should be used if the
3934 depended-on package is required for the depending
3935 package to provide a significant amount of
3940 The <tt>Depends</tt> field should also be used if the
3941 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
3942 <prgn>postrm</prgn> scripts require the package to be
3943 present in order to run. Note, however, that the
3944 <prgn>postrm</prgn> cannot rely on any non-essential
3945 packages to be present during the <tt>purge</tt>
3949 <tag><tt>Recommends</tt></tag>
3952 This declares a strong, but not absolute, dependency.
3956 The <tt>Recommends</tt> field should list packages
3957 that would be found together with this one in all but
3958 unusual installations.
3962 <tag><tt>Suggests</tt></tag>
3964 This is used to declare that one package may be more
3965 useful with one or more others. Using this field
3966 tells the packaging system and the user that the
3967 listed packages are related to this one and can
3968 perhaps enhance its usefulness, but that installing
3969 this one without them is perfectly reasonable.
3972 <tag><tt>Enhances</tt></tag>
3974 This field is similar to Suggests but works in the
3975 opposite direction. It is used to declare that a
3976 package can enhance the functionality of another
3980 <tag><tt>Pre-Depends</tt></tag>
3983 This field is like <tt>Depends</tt>, except that it
3984 also forces <prgn>dpkg</prgn> to complete installation
3985 of the packages named before even starting the
3986 installation of the package which declares the
3987 pre-dependency, as follows:
3991 When a package declaring a pre-dependency is about to
3992 be <em>unpacked</em> the pre-dependency can be
3993 satisfied if the depended-on package is either fully
3994 configured, <em>or even if</em> the depended-on
3995 package(s) are only unpacked or half-configured,
3996 provided that they have been configured correctly at
3997 some point in the past (and not removed or partially
3998 removed since). In this case, both the
3999 previously-configured and currently unpacked or
4000 half-configured versions must satisfy any version
4001 clause in the <tt>Pre-Depends</tt> field.
4005 When the package declaring a pre-dependency is about
4006 to be <em>configured</em>, the pre-dependency will be
4007 treated as a normal <tt>Depends</tt>, that is, it will
4008 be considered satisfied only if the depended-on
4009 package has been correctly configured.
4013 <tt>Pre-Depends</tt> should be used sparingly,
4014 preferably only by packages whose premature upgrade or
4015 installation would hamper the ability of the system to
4016 continue with any upgrade that might be in progress.
4020 <tt>Pre-Depends</tt> are also required if the
4021 <prgn>preinst</prgn> script depends on the named
4022 package. It is best to avoid this situation if
4030 When selecting which level of dependency to use you should
4031 consider how important the depended-on package is to the
4032 functionality of the one declaring the dependency. Some
4033 packages are composed of components of varying degrees of
4034 importance. Such a package should list using
4035 <tt>Depends</tt> the package(s) which are required by the
4036 more important components. The other components'
4037 requirements may be mentioned as Suggestions or
4038 Recommendations, as appropriate to the components' relative
4043 <sect id="conflicts">
4044 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4047 When one binary package declares a conflict with another
4048 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4049 refuse to allow them to be installed on the system at the
4054 If one package is to be installed, the other must be removed
4055 first - if the package being installed is marked as
4056 replacing (see <ref id="replaces">) the one on the system,
4057 or the one on the system is marked as deselected, or both
4058 packages are marked <tt>Essential</tt>, then
4059 <prgn>dpkg</prgn> will automatically remove the package
4060 which is causing the conflict, otherwise it will halt the
4061 installation of the new package with an error. This
4062 mechanism is specifically designed to produce an error when
4063 the installed package is <tt>Essential</tt>, but the new
4068 A package will not cause a conflict merely because its
4069 configuration files are still installed; it must be at least
4074 A special exception is made for packages which declare a
4075 conflict with their own package name, or with a virtual
4076 package which they provide (see below): this does not
4077 prevent their installation, and allows a package to conflict
4078 with others providing a replacement for it. You use this
4079 feature when you want the package in question to be the only
4080 package providing some feature.
4084 A <tt>Conflicts</tt> entry should almost never have an
4085 "earlier than" version clause. This would prevent
4086 <prgn>dpkg</prgn> from upgrading or installing the package
4087 which declared such a conflict until the upgrade or removal
4088 of the conflicted-with package had been completed.
4092 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4096 As well as the names of actual ("concrete") packages, the
4097 package relationship fields <tt>Depends</tt>,
4098 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4099 <tt>Pre-Depends</tt>, <tt>Conflicts</tt>,
4100 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4101 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4102 may mention "virtual packages".
4106 A <em>virtual package</em> is one which appears in the
4107 <tt>Provides</tt> control file field of another package.
4108 The effect is as if the package(s) which provide a
4109 particular virtual package name had been listed by name
4110 everywhere the virtual package name appears. (See also <ref
4115 If there are both concrete and virtual packages of the same
4116 name, then the dependency may be satisfied (or the conflict
4117 caused) by either the concrete package with the name in
4118 question or any other concrete package which provides the
4119 virtual package with the name in question. This is so that,
4120 for example, supposing we have
4121 <example compact="compact">
4125 and someone else releases an enhanced version of the
4126 <tt>bar</tt> package (for example, a non-US variant), they
4128 <example compact="compact">
4132 and the <tt>bar-plus</tt> package will now also satisfy the
4133 dependency for the <tt>foo</tt> package.
4137 If a dependency or a conflict has a version number attached
4138 then only real packages will be considered to see whether
4139 the relationship is satisfied (or the prohibition violated,
4140 for a conflict) - it is assumed that a real package which
4141 provides the virtual package is not of the "right" version.
4142 So, a <tt>Provides</tt> field may not contain version
4143 numbers, and the version number of the concrete package
4144 which provides a particular virtual package will not be
4145 looked at when considering a dependency on or conflict with
4146 the virtual package name.
4150 It is likely that the ability will be added in a future
4151 release of <prgn>dpkg</prgn> to specify a version number for
4152 each virtual package it provides. This feature is not yet
4153 present, however, and is expected to be used only
4158 If you want to specify which of a set of real packages
4159 should be the default to satisfy a particular dependency on
4160 a virtual package, you should list the real package as an
4161 alternative before the virtual one.
4166 <sect id="replaces"><heading>Overwriting files and replacing
4167 packages - <tt>Replaces</tt></heading>
4170 Packages can declare in their control file that they should
4171 overwrite files in certain other packages, or completely
4172 replace other packages. The <tt>Replaces</tt> control file
4173 field has these two distinct purposes.
4176 <sect1><heading>Overwriting files in other packages</heading>
4179 Firstly, as mentioned before, it is usually an error for a
4180 package to contain files which are on the system in
4185 However, if the overwriting package declares that it
4186 <tt>Replaces</tt> the one containing the file being
4187 overwritten, then <prgn>dpkg</prgn> will replace the file
4188 from the old package with that from the new. The file
4189 will no longer be listed as "owned" by the old package.
4193 If a package is completely replaced in this way, so that
4194 <prgn>dpkg</prgn> does not know of any files it still
4195 contains, it is considered to have "disappeared". It will
4196 be marked as not wanted on the system (selected for
4197 removal) and not installed. Any <tt>conffile</tt>s
4198 details noted for the package will be ignored, as they
4199 will have been taken over by the overwriting package. The
4200 package's <prgn>postrm</prgn> script will be run with a
4201 special argument to allow the package to do any final
4202 cleanup required. See <ref id="mscriptsinstact">.
4206 If an installed package, <tt>foo</tt> say, declares that
4207 it replaces another, <tt>bar</tt>, and an attempt is made
4208 to install <tt>bar</tt>, <prgn>dpkg</prgn> will discard
4209 files in the <tt>bar</tt> package which would overwrite
4210 those already present in <tt>foo</tt>. This is so that
4211 you can install an older version of a package without
4216 For this usage of <tt>Replaces</tt>, virtual packages (see
4217 <ref id="virtual">) are not considered when looking at a
4218 <tt>Replaces</tt> field - the packages declared as being
4219 replaced must be mentioned by their real names.
4223 Furthermore, this usage of <tt>Replaces</tt> only takes
4224 effect when both packages are at least partially on the
4225 system at once, so that it can only happen if they do not
4226 conflict or if the conflict has been overridden.
4231 <sect1><heading>Replacing whole packages, forcing their
4235 Secondly, <tt>Replaces</tt> allows the packaging system to
4236 resolve which package should be removed when there is a
4237 conflict - see <ref id="conflicts">. This usage only
4238 takes effect when the two packages <em>do</em> conflict,
4239 so that the two usages of this field do not interfere with
4244 In this situation, the package declared as being replaced
4245 can be a virtual package, so for example, all mail
4246 transport agents (MTAs) would have the following fields in
4247 their control files:
4248 <example compact="compact">
4249 Provides: mail-transport-agent
4250 Conflicts: mail-transport-agent
4251 Replaces: mail-transport-agent
4253 ensuring that only one MTA can be installed at any one
4258 <sect id="sourcebinarydeps">
4259 <heading>Relationships between source and binary packages -
4260 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4261 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4265 Source packages that require certain binary packages to be
4266 installed or absent at the time of building the package
4267 can declare relationships to those binary packages.
4271 This is done using the <tt>Build-Depends</tt>,
4272 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4273 <tt>Build-Conflicts-Indep</tt> control file fields.
4277 Build-dependencies on "build-essential" binary packages can be
4278 omitted. Please see <ref id="pkg-relations"> for more information.
4282 The dependencies and conflicts they define must be satisfied
4283 (as defined earlier for binary packages) in order to invoke
4284 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4286 If you make "build-arch" or "binary-arch", you need
4287 Build-Depends. If you make "build-indep" or
4288 "binary-indep", you need Build-Depends and
4289 Build-Depends-Indep. If you make "build" or "binary",
4293 There is no Build-Depends-Arch; the autobuilders will
4294 only need the Build-Depends if they know how to build
4295 only build-arch and binary-arch. Anyone building the
4296 build-indep/binary-indep targets is basically assumed to
4297 be building the whole package and so installs all build
4301 The purpose of the original split, I recall, was so that
4302 the autobuilders wouldn't need to install extra packages
4303 needed only for the binary-indep targets. But without a
4304 build-arch/build-indep split, this didn't work, since
4305 most of the work is done in the build target, not in the
4311 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4313 The <tt>Build-Depends</tt> and
4314 <tt>Build-Conflicts</tt> fields must be satisfied when
4315 any of the following targets is invoked:
4316 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4317 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4318 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4320 <tag><tt>Build-Depends-Indep</tt>,
4321 <tt>Build-Conflicts-Indep</tt></tag>
4323 The <tt>Build-Depends-Indep</tt> and
4324 <tt>Build-Conflicts-Indep</tt> fields must be
4325 satisfied when any of the following targets is
4326 invoked: <tt>build</tt>, <tt>clean</tt>,
4327 <tt>build-indep</tt>, <tt>binary</tt> and
4328 <tt>binary-indep</tt>.
4338 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4341 Packages containing shared libraries must be constructed with
4342 a little care to make sure that the shared library is always
4343 available. This is especially important for packages whose
4344 shared libraries are vitally important, such as the C library
4345 (currently <tt>libc6</tt>).
4349 Packages involving shared libraries should be split up into
4350 several binary packages. This section mostly deals with how
4351 this separation is to be accomplished; rules for files within
4352 the shared library packages are in <ref id="libraries"> instead.
4355 <sect id="sharedlibs-runtime">
4356 <heading>Run-time shared libraries</heading>
4359 The run-time shared library needs to be placed in a package called
4360 <package><var>libraryname</var><var>soversion</var></package>, where
4361 <file><var>soversion</var></file> is the version number in the
4362 soname of the shared library<footnote>
4363 The soname is the shared object name: it's the thing
4364 that has to match exactly between building an executable
4365 and running it for the dynamic linker to be able run the
4366 program. For example, if the soname of the library is
4367 <file>libfoo.so.6</file>, the library package would be
4368 called <file>libfoo6</file>.
4370 Alternatively, if it would be confusing to directly append
4371 <var>soversion</var> to <var>libraryname</var> (e.g. because
4372 <var>libraryname</var> itself ends in a number), you may use
4373 <package><var>libraryname</var>-<var>soversion</var></package> and
4374 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4379 If you have several shared libraries built from the same
4380 source tree you may lump them all together into a single
4381 shared library package, provided that you change all of
4382 their sonames at once (so that you don't get filename
4383 clashes if you try to install different versions of the
4384 combined shared libraries package).
4388 The package should install the shared libraries under
4389 their normal names. For example, the <package>libgdbmg1</package>
4390 package should install <file>libgdbm.so.1.7.3</file> as
4391 <file>/usr/lib/libgdbm.so.1.7.3</file>. The files should not be
4392 renamed or re-linked by any <prgn>prerm</prgn> or
4393 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4394 of renaming things safely without affecting running programs,
4395 and attempts to interfere with this are likely to lead to
4400 Shared libraries should not be installed executable, since
4401 the dynamic linker does not require this and trying to
4402 execute a shared library usually results in a core dump.
4406 The run-time library package should include the symbolic link that
4407 <prgn>ldconfig</prgn> would create for the shared libraries.
4408 For example, the <package>libgdbmg1</package> package should include
4409 a symbolic link from <file>/usr/lib/libgdbm.so.1</file> to
4410 <file>libgdbm.so.1.7.3</file>. This is needed so that the dynamic
4411 linker (for example <prgn>ld.so</prgn> or
4412 <prgn>ld-linux.so.*</prgn>) can find the library between the
4413 time that <prgn>dpkg</prgn> installs it and the time that
4414 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4416 The package management system requires the library to be
4417 placed before the symbolic link pointing to it in the
4418 <file>.deb</file> file. This is so that when
4419 <prgn>dpkg</prgn> comes to install the symlink
4420 (overwriting the previous symlink pointing at an older
4421 version of the library), the new shared library is already
4422 in place. In the past, this was achieved by creating the
4423 library in the temporary packaging directory before
4424 creating the symlink. Unfortunately, this was not always
4425 effective, since the building of the tar file in the
4426 <file>.deb</file> depended on the behavior of the underlying
4427 file system. Some file systems (such as reiserfs) reorder
4428 the files so that the order of creation is forgotten.
4429 Since version 1.7.0, <prgn>dpkg</prgn>
4430 reorders the files itself as necessary when building a
4431 package. Thus it is no longer important to concern
4432 oneself with the order of file creation.
4436 <sect1 id="ldconfig">
4437 <heading><tt>ldconfig</tt></heading>
4440 Any package installing shared libraries in one of the default
4441 library directories of the dynamic linker (which are currently
4442 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4443 listed in <file>/etc/ld.so.conf</file><footnote>
4445 <list compact="compact">
4446 <item>/usr/X11R6/lib/Xaw3d</item>
4447 <item>/usr/local/lib</item>
4448 <item>/usr/lib/libc5-compat</item>
4449 <item>/lib/libc5-compat</item>
4450 <item>/usr/X11R6/lib</item>
4453 must use <prgn>ldconfig</prgn> to update the shared library
4458 The package must call <prgn>ldconfig</prgn> in the
4459 <prgn>postinst</prgn> script if the first argument is
4460 <tt>configure</tt>; the <prgn>postinst</prgn> script may
4461 optionally invoke <prgn>ldconfig</prgn> at other times. The
4462 package should call <prgn>ldconfig</prgn> in the
4463 <prgn>postrm</prgn> script if the first argument is
4464 <tt>remove</tt>. The maintainer scripts must not invoke
4465 <prgn>ldconfig</prgn> under any circumstances other than those
4466 described in this paragraph.<footnote>
4468 During install or upgrade, the preinst is called before
4469 the new files are installed, so calling "ldconfig" is
4470 pointless. The preinst of an existing package can also be
4471 called if an upgrade fails. However, this happens during
4472 the critical time when a shared libs may exist on-disk
4473 under a temporary name. Thus, it is dangerous and
4474 forbidden by current policy to call "ldconfig" at this
4479 When a package is installed or upgraded, "postinst
4480 configure" runs after the new files are safely on-disk.
4481 Since it is perfectly safe to invoke ldconfig
4482 unconditionally in a postinst, it is OK for a package to
4483 simply put ldconfig in its postinst without checking the
4484 argument. The postinst can also be called to recover from
4485 a failed upgrade. This happens before any new files are
4486 unpacked, so there is no reason to call "ldconfig" at this
4491 For a package that is being removed, prerm is
4492 called with all the files intact, so calling ldconfig is
4493 useless. The other calls to "prerm" happen in the case of
4494 upgrade at a time when all the files of the old package
4495 are on-disk, so again calling "ldconfig" is pointless.
4499 postrm, on the other hand, is called with the "remove"
4500 argument just after the files are removed, so this is the
4501 proper time to call "ldconfig" to notify the system of the
4502 fact shared libraries from the package are removed.
4503 The postrm can be called at several other times. At the
4504 time of "postrm purge", "postrm abort-install", or "postrm
4505 abort-upgrade", calling "ldconfig" is useless because the
4506 shared lib files are not on-disk. However, when "postrm"
4507 is invoked with arguments "upgrade", "failed-upgrade", or
4508 "disappear", a shared lib may exist on-disk under a
4517 <sect id="sharedlibs-runtime-progs">
4518 <heading>Run-time support programs</heading>
4521 If your package has some run-time support programs which use
4522 the shared library you must not put them in the shared
4523 library package. If you do that then you won't be able to
4524 install several versions of the shared library without
4525 getting filename clashes.
4529 Instead, either create another package for the runtime binaries
4530 (this package might typically be named
4531 <package><var>libraryname</var>-runtime</package>; note the absence
4532 of the <var>soversion</var> in the package name), or if the
4533 development package is small, include them in there.
4537 <sect id="sharedlibs-static">
4538 <heading>Static libraries</heading>
4541 The static library (<file><var>libraryname.a</var></file>)
4542 is usually provided in addition to the shared version.
4543 It is placed into the development package (see below).
4547 In some cases, it is acceptable for a library to be
4548 available in static form only; these cases include:
4550 <item>libraries for languages whose shared library support
4551 is immature or unstable</item>
4552 <item>libraries whose interfaces are in flux or under
4553 development (commonly the case when the library's
4554 major version number is zero, or where the ABI breaks
4555 across patchlevels)</item>
4556 <item>libraries which are explicitly intended to be
4557 available only in static form by their upstream
4562 <sect id="sharedlibs-dev">
4563 <heading>Development files</heading>
4566 The development files associated to a shared library need to be
4567 placed in a package called
4568 <package><var>libraryname</var><var>soversion</var>-dev</package>,
4569 or if you prefer only to support one development version at a
4570 time, <package><var>libraryname</var>-dev</package>.
4574 In case several development versions of a library exist, you may
4575 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
4576 <ref id="conflicts">) to ensure that the user only installs one
4577 development version at a time (as different development versions are
4578 likely to have the same header files in them, which would cause a
4579 filename clash if both were installed).
4583 The development package should contain a symlink for the associated
4584 shared library without a version number. For example, the
4585 <package>libgdbmg1-dev</package> package should include a symlink
4586 from <file>/usr/lib/libgdbm.so</file> to
4587 <file>libgdbm.so.1.7.3</file>. This symlink is needed by the linker
4588 (<prgn>ld</prgn>) when compiling packages, as it will only look for
4589 <file>libgdbm.so</file> when compiling dynamically.
4593 <sect id="sharedlibs-intradeps">
4594 <heading>Dependencies between the packages of the same library</heading>
4597 Typically the development version should have an exact
4598 version dependency on the runtime library, to make sure that
4599 compilation and linking happens correctly. The
4600 <tt>${Source-Version}</tt> substitution variable can be
4601 useful for this purpose.
4605 <sect id="sharedlibs-shlibdeps">
4606 <heading>Dependencies between the library and other packages -
4607 the <tt>shlibs</tt> system</heading>
4610 If a package contains a binary or library which links to a
4611 shared library, we must ensure that when the package is
4612 installed on the system, all of the libraries needed are
4613 also installed. This requirement led to the creation of the
4614 <tt>shlibs</tt> system, which is very simple in its design:
4615 any package which <em>provides</em> a shared library also
4616 provides information on the package dependencies required to
4617 ensure the presence of this library, and any package which
4618 <em>uses</em> a shared library uses this information to
4619 determine the dependencies it requires. The files which
4620 contain the mapping from shared libraries to the necessary
4621 dependency information are called <file>shlibs</file> files.
4625 Thus, when a package is built which contains any shared
4626 libraries, it must provide a <file>shlibs</file> file for other
4627 packages to use, and when a package is built which contains
4628 any shared libraries or compiled binaries, it must run
4629 <prgn>dpkg-shlibdeps</prgn> on these to determine the
4630 libraries used and hence the dependencies needed by this
4633 In the past, the shared libraries linked to were
4634 determined by calling <prgn>ldd</prgn>, but now
4635 <prgn>objdump</prgn> is used to do this. The only
4636 change this makes to package building is that
4637 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
4638 libraries, whereas in the past this was unnecessary.
4639 The rest of this footnote explains the advantage that
4644 We say that a binary <tt>foo</tt> <em>directly</em> uses
4645 a library <tt>libbar</tt> if it is explicitly linked
4646 with that library (that is, it uses the flag
4647 <tt>-lbar</tt> during the linking stage). Other
4648 libraries that are needed by <tt>libbar</tt> are linked
4649 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
4650 linker will load them automatically when it loads
4651 <tt>libbar</tt>. A package should depend on
4652 the libraries it directly uses, and the dependencies for
4653 those libraries should automatically pull in the other
4658 Unfortunately, the <prgn>ldd</prgn> program shows both
4659 the directly and indirectly used libraries, meaning that
4660 the dependencies determined included both direct and
4661 indirect dependencies. The use of <prgn>objdump</prgn>
4662 avoids this problem by determining only the directly
4667 A good example of where this helps is the following. We
4668 could update <tt>libimlib</tt> with a new version that
4669 supports a new graphics format called dgf (but retaining
4670 the same major version number). If we used the old
4671 <prgn>ldd</prgn> method, every package that uses
4672 <tt>libimlib</tt> would need to be recompiled so it
4673 would also depend on <tt>libdgf</tt> or it wouldn't run
4674 due to missing symbols. However with the new system,
4675 packages using <tt>libimlib</tt> can rely on
4676 <tt>libimlib</tt> itself having the dependency on
4677 <tt>libdgf</tt> and so they would not need rebuilding.
4683 In the following sections, we will first describe where the
4684 various <tt>shlibs</tt> files are to be found, then how to
4685 use <prgn>dpkg-shlibdeps</prgn>, and finally the
4686 <tt>shlibs</tt> file format and how to create them if your
4687 package contains a shared library.
4691 <heading>The <tt>shlibs</tt> files present on the system</heading>
4694 There are several places where <tt>shlibs</tt> files are
4695 found. The following list gives them in the order in which
4696 they are read by <prgn>dpkg-shlibdeps</prgn>. (The first
4697 one which gives the required information is used.)
4703 <p><file>debian/shlibs.local</file></p>
4706 This lists overrides for this package. Its use is
4707 described below (see <ref id="shlibslocal">).
4712 <p><file>/etc/dpkg/shlibs.override</file></p>
4715 This lists global overrides. This list is normally
4716 empty. It is maintained by the local system
4722 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
4725 When packages are being built, any
4726 <file>debian/shlibs</file> files are copied into the
4727 control file area of the temporary build directory and
4728 given the name <file>shlibs</file>. These files give
4729 details of any shared libraries included in the
4731 An example may help here. Let us say that the
4732 source package <tt>foo</tt> generates two binary
4733 packages, <tt>libfoo2</tt> and
4734 <tt>foo-runtime</tt>. When building the binary
4735 packages, the two packages are created in the
4736 directories <file>debian/libfoo2</file> and
4737 <file>debian/foo-runtime</file> respectively.
4738 (<file>debian/tmp</file> could be used instead of one
4739 of these.) Since <tt>libfoo2</tt> provides the
4740 <tt>libfoo</tt> shared library, it will require a
4741 <tt>shlibs</tt> file, which will be installed in
4742 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
4744 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
4745 when <prgn>dpkg-shlibdeps</prgn> is run on the
4747 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
4749 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
4750 determine whether <tt>foo-prog</tt>'s library
4751 dependencies are satisfied by any of the libraries
4752 provided by <tt>libfoo2</tt>. For this reason,
4753 <prgn>dpkg-shlibdeps</prgn> must only be run once
4754 all of the individual binary packages'
4755 <tt>shlibs</tt> files have been installed into the
4762 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
4765 These are the <file>shlibs</file> files corresponding to
4766 all of the packages installed on the system, and are
4767 maintained by the relevant package maintainers.
4772 <p><file>/etc/dpkg/shlibs.default</file></p>
4775 This file lists any shared libraries whose packages
4776 have failed to provide correct <file>shlibs</file> files.
4777 It was used when the <file>shlibs</file> setup was first
4778 introduced, but it is now normally empty. It is
4779 maintained by the <tt>dpkg</tt> maintainer.
4787 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
4788 <file>shlibs</file> files</heading>
4791 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
4792 <file>debian/rules</file> file. If your package contains only
4793 compiled binaries and libraries (but no scripts), you can
4794 use a command such as:
4795 <example compact="compact">
4796 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
4797 debian/tmp/usr/lib/*
4799 Otherwise, you will need to explicitly list the compiled
4800 binaries and libraries.<footnote>
4801 If you are using <tt>debhelper</tt>, the
4802 <prgn>dh_shlibdeps</prgn> program will do this work for
4803 you. It will also correctly handle multi-binary
4809 This command puts the dependency information into the
4810 <file>debian/substvars</file> file, which is then used by
4811 <prgn>dpkg-gencontrol</prgn>. You will need to place a
4812 <tt>${shlib:Depends}</tt> variable in the <tt>Depends</tt>
4813 field in the control file for this to work.
4817 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
4818 done. If it does complain you might need to create your own
4819 <file>debian/shlibs.local</file> file, as explained below (see
4820 <ref id="shlibslocal">).
4824 If you have multiple binary packages, you will need to call
4825 <prgn>dpkg-shlibdeps</prgn> on each one which contains
4826 compiled libraries or binaries. In such a case, you will
4827 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
4828 utilities to specify a different <file>substvars</file> file.
4829 For more details on this and other options, see <manref
4830 name="dpkg-shlibdeps" section="1">.
4835 <heading>The <file>shlibs</file> File Format</heading>
4838 Each <file>shlibs</file> file has the same format. Lines
4839 beginning with <tt>#</tt> are considered to be comments and
4840 are ignored. Each line is of the form:
4841 <example compact="compact">
4842 <var>library-name</var> <var>soname-version-number</var> <var>dependencies ...</var>
4847 We will explain this by reference to the example of the
4848 <tt>zlib1g</tt> package, which (at the time of writing)
4849 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
4853 <var>library-name</var> is the name of the shared library,
4854 in this case <tt>libz</tt>. (This must match the name part
4855 of the soname, see below.)
4859 <var>soname-version-number</var> is the version part of the
4860 soname of the library. The soname is the thing that must
4861 exactly match for the library to be recognized by the
4862 dynamic linker, and is usually of the form
4863 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
4864 example, <tt>libz.so.1</tt>.<footnote>
4865 This can be determined using the command
4866 <example compact="compact">
4867 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
4870 The version part is the part which comes after
4871 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
4875 <var>dependencies</var> has the same syntax as a dependency
4876 field in a binary package control file. It should give
4877 details of which packages are required to satisfy a binary
4878 built against the version of the library contained in the
4879 package. See <ref id="depsyntax"> for details.
4883 In our example, if the first version of the <tt>zlib1g</tt>
4884 package which contained a minor number of at least
4885 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
4886 <tt>shlibs</tt> entry for this library could say:
4887 <example compact="compact">
4888 libz 1 zlib1g (>= 1:1.1.3)
4890 The version-specific dependency is to avoid warnings from
4891 the dynamic linker about using older shared libraries with
4897 <heading>Providing a <file>shlibs</file> file</heading>
4900 If your package provides a shared library, you should create
4901 a <file>shlibs</file> file following the format described above.
4902 It is usual to call this file <file>debian/shlibs</file> (but if
4903 you have multiple binary packages, you might want to call it
4904 <file>debian/shlibs.<var>package</var></file> instead). Then
4905 let <file>debian/rules</file> install it in the control area:
4906 <example compact="compact">
4907 install -m644 debian/shlibs debian/tmp/DEBIAN
4909 or, in the case of a multi-binary package:
4910 <example compact="compact">
4911 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
4913 An alternative way of doing this is to create the
4914 <file>shlibs</file> file in the control area directly from
4915 <file>debian/rules</file> without using a <file>debian/shlibs</file>
4916 file at all,<footnote>
4917 This is what <prgn>dh_makeshlibs</prgn> in the
4918 <tt>debhelper</tt> suite does.
4920 since the <file>debian/shlibs</file> file itself is ignored by
4921 <prgn>dpkg-shlibdeps</prgn>.
4925 As <prgn>dpkg-shlibdeps</prgn> reads the
4926 <file>DEBIAN/shlibs</file> files in all of the binary packages
4927 being built from this source package, all of the
4928 <file>DEBIAN/shlibs</file> files should be installed before
4929 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
4934 <sect1 id="shlibslocal">
4935 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
4938 This file is intended only as a <em>temporary</em> fix if
4939 your binaries or libraries depend on a library whose package
4940 does not yet provide a correct <file>shlibs</file> file.
4944 We will assume that you are trying to package a binary
4945 <tt>foo</tt>. When you try running
4946 <prgn>dpkg-shlibdeps</prgn> you get the following error
4947 message (<tt>-O</tt> displays the dependency information on
4948 <tt>stdout</tt> instead of writing it to
4949 <tt>debian/substvars</tt>, and the lines have been wrapped
4950 for ease of reading):
4951 <example compact="compact">
4952 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
4953 dpkg-shlibdeps: warning: unable to find dependency
4954 information for shared library libbar (soname 1,
4955 path /usr/lib/libbar.so.1, dependency field Depends)
4956 shlibs:Depends=libc6 (>= 2.2.2-2)
4958 You can then run <prgn>ldd</prgn> on the binary to find the
4959 full location of the library concerned:
4960 <example compact="compact">
4962 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
4963 libc.so.6 => /lib/libc.so.6 (0x40032000)
4964 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
4966 So the <prgn>foo</prgn> binary depends on the
4967 <prgn>libbar</prgn> shared library, but no package seems to
4968 provide a <file>*.shlibs</file> file handling
4969 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
4970 determine the package responsible:
4971 <example compact="compact">
4972 $ dpkg -S /usr/lib/libbar.so.1
4973 bar1: /usr/lib/libbar.so.1
4974 $ dpkg -s bar1 | grep Version
4977 This tells us that the <tt>bar1</tt> package, version 1.0-1,
4978 is the one we are using. Now we can file a bug against the
4979 <tt>bar1</tt> package and create our own
4980 <file>debian/shlibs.local</file> to locally fix the problem.
4981 Including the following line into your
4982 <file>debian/shlibs.local</file> file:
4983 <example compact="compact">
4984 libbar 1 bar1 (>= 1.0-1)
4986 should allow the package build to work.
4990 As soon as the maintainer of <tt>bar1</tt> provides a
4991 correct <file>shlibs</file> file, you should remove this line
4992 from your <file>debian/shlibs.local</file> file. (You should
4993 probably also then have a versioned <tt>Build-Depends</tt>
4994 on <tt>bar1</tt> to help ensure that others do not have the
4995 same problem building your package.)
5004 <chapt id="opersys"><heading>The Operating System</heading>
5007 <heading>Filesystem hierarchy</heading>
5011 <heading>Filesystem Structure</heading>
5014 The location of all installed files and directories must
5015 comply with the Filesystem Hierarchy Standard (FHS),
5016 version 2.1, except where doing so would violate other
5017 terms of Debian Policy. The version of this document
5018 referred here can be found in the <tt>debian-policy</tt>
5020 <url id="http://www.debian.org/doc/packaging-manuals/fhs/"
5021 name="FHS (Debian copy)"> alongside this manual (or, if
5022 you have the <package>debian-policy</package> installed,
5024 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5025 (local copy)">). The
5026 latest version, which may be a more recent version, may
5028 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5029 Specific questions about following the standard may be
5030 asked on the <tt>debian-devel</tt> mailing list, or
5031 referred to the FHS mailing list (see the
5032 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5038 <heading>Site-specific programs</heading>
5041 As mandated by the FHS, packages must not place any
5042 files in <file>/usr/local</file>, either by putting them in
5043 the file system archive to be unpacked by <prgn>dpkg</prgn>
5044 or by manipulating them in their maintainer scripts.
5048 However, the package may create empty directories below
5049 <file>/usr/local</file> so that the system administrator knows
5050 where to place site-specific files. These directories
5051 should be removed on package removal if they are
5056 Note, that this applies only to directories <em>below</em>
5057 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
5058 Packages must not create sub-directories in the directory
5059 <file>/usr/local</file> itself, except those listed in FHS,
5060 section 4.5. However, you may create directories below
5061 them as you wish. You must not remove any of the
5062 directories listed in 4.5, even if you created them.
5066 Since <file>/usr/local</file> can be mounted read-only from a
5067 remote server, these directories must be created and
5068 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5069 maintainer scripts and not be included in the
5070 <file>.deb</file> archive. These scripts must not fail if
5071 either of these operations fail.
5075 For example, the <tt>emacsen-common</tt> package could
5076 contain something like
5077 <example compact="compact">
5078 if [ ! -e /usr/local/share/emacs ]
5080 if mkdir /usr/local/share/emacs 2>/dev/null
5082 chown root:staff /usr/local/share/emacs
5083 chmod 2775 /usr/local/share/emacs
5087 in its <prgn>postinst</prgn> script, and
5088 <example compact="compact">
5089 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5090 rmdir /usr/local/share/emacs 2>/dev/null || true
5092 in the <prgn>prerm</prgn> script. (Note that this form is
5093 used to ensure that if the script is interrupted, the
5094 directory <file>/usr/local/share/emacs</file> will still be
5099 If you do create a directory in <file>/usr/local</file> for
5100 local additions to a package, you should ensure that
5101 settings in <file>/usr/local</file> take precedence over the
5102 equivalents in <file>/usr</file>.
5106 However, because <file>/usr/local</file> and its contents are
5107 for exclusive use of the local administrator, a package
5108 must not rely on the presence or absence of files or
5109 directories in <file>/usr/local</file> for normal operation.
5113 The <file>/usr/local</file> directory itself and all the
5114 subdirectories created by the package should (by default) have
5115 permissions 2775 (group-writable and set-group-id) and be
5116 owned by <tt>root.staff</tt>.
5121 <heading>The system-wide mail directory</heading>
5123 The system-wide mail directory is <file>/var/mail</file>. This
5124 directory is part of the base system and should not owned
5125 by any particular mail agents. The use of the old
5126 location <file>/var/spool/mail</file> is deprecated, even
5127 though the spool may still be physically located there.
5128 To maintain partial upgrade compatibility for systems
5129 which have <file>/var/spool/mail</file> as their physical mail
5130 spool, packages using <file>/var/mail</file> must depend on
5131 either <package>libc6</package> (>= 2.1.3-13), or on
5132 <package>base-files</package> (>= 2.2.0), or on later
5133 versions of either one of these packages.
5139 <heading>Users and groups</heading>
5142 <heading>Introduction</heading>
5144 The Debian system can be configured to use either plain or
5149 Some user ids (UIDs) and group ids (GIDs) are reserved
5150 globally for use by certain packages. Because some
5151 packages need to include files which are owned by these
5152 users or groups, or need the ids compiled into binaries,
5153 these ids must be used on any Debian system only for the
5154 purpose for which they are allocated. This is a serious
5155 restriction, and we should avoid getting in the way of
5156 local administration policies. In particular, many sites
5157 allocate users and/or local system groups starting at 100.
5161 Apart from this we should have dynamically allocated ids,
5162 which should by default be arranged in some sensible
5163 order, but the behavior should be configurable.
5167 Packages other than <tt>base-passwd</tt> must not modify
5168 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5169 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5174 <heading>UID and GID classes</heading>
5176 The UID and GID numbers are divided into classes as
5182 Globally allocated by the Debian project, the same
5183 on every Debian system. These ids will appear in
5184 the <file>passwd</file> and <file>group</file> files of all
5185 Debian systems, new ids in this range being added
5186 automatically as the <tt>base-passwd</tt> package is
5191 Packages which need a single statically allocated
5192 uid or gid should use one of these; their
5193 maintainers should ask the <tt>base-passwd</tt>
5201 Dynamically allocated system users and groups.
5202 Packages which need a user or group, but can have
5203 this user or group allocated dynamically and
5204 differently on each system, should use <tt>adduser
5205 --system</tt> to create the group and/or user.
5206 <prgn>adduser</prgn> will check for the existence of
5207 the user or group, and if necessary choose an unused
5208 id based on the ranges specified in
5209 <file>adduser.conf</file>.
5213 <tag>1000-29999:</tag>
5216 Dynamically allocated user accounts. By default
5217 <prgn>adduser</prgn> will choose UIDs and GIDs for
5218 user accounts in this range, though
5219 <file>adduser.conf</file> may be used to modify this
5224 <tag>30000-59999:</tag>
5229 <tag>60000-64999:</tag>
5232 Globally allocated by the Debian project, but only
5233 created on demand. The ids are allocated centrally
5234 and statically, but the actual accounts are only
5235 created on users' systems on demand.
5239 These ids are for packages which are obscure or
5240 which require many statically-allocated ids. These
5241 packages should check for and create the accounts in
5242 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5243 <prgn>adduser</prgn> if it has this facility) if
5244 necessary. Packages which are likely to require
5245 further allocations should have a "hole" left after
5246 them in the allocation, to give them room to
5251 <tag>65000-65533:</tag>
5259 User <tt>nobody</tt>. The corresponding gid refers
5260 to the group <tt>nogroup</tt>.
5267 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5268 not</em> be used, because it is the error return
5277 <sect id="sysvinit">
5278 <heading>System run levels and <file>init.d</file> scripts</heading>
5280 <sect1 id="/etc/init.d">
5281 <heading>Introduction</heading>
5284 The <file>/etc/init.d</file> directory contains the scripts
5285 executed by <prgn>init</prgn> at boot time and when the
5286 init state (or "runlevel") is changed (see <manref
5287 name="init" section="8">).
5291 There are at least two different, yet functionally
5292 equivalent, ways of handling these scripts. For the sake
5293 of simplicity, this document describes only the symbolic
5294 link method. However, it must not be assumed by maintainer
5295 scripts that this method is being used, and any automated
5296 manipulation of the various runlevel behaviours by
5297 maintainer scripts must be performed using
5298 <prgn>update-rc.d</prgn> as described below and not by
5299 manually installing or removing symlinks. For information
5300 on the implementation details of the other method,
5301 implemented in the <tt>file-rc</tt> package, please refer
5302 to the documentation of that package.
5306 These scripts are referenced by symbolic links in the
5307 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5308 runlevels, <prgn>init</prgn> looks in the directory
5309 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5310 execute, where <tt><var>n</var></tt> is the runlevel that
5311 is being changed to, or <tt>S</tt> for the boot-up
5316 The names of the links all have the form
5317 <file>S<var>mm</var><var>script</var></file> or
5318 <file>K<var>mm</var><var>script</var></file> where
5319 <var>mm</var> is a two-digit number and <var>script</var>
5320 is the name of the script (this should be the same as the
5321 name of the actual script in <file>/etc/init.d</file>).
5325 When <prgn>init</prgn> changes runlevel first the targets
5326 of the links whose names start with a <tt>K</tt> are
5327 executed, each with the single argument <tt>stop</tt>,
5328 followed by the scripts prefixed with an <tt>S</tt>, each
5329 with the single argument <tt>start</tt>. (The links are
5330 those in the <file>/etc/rc<var>n</var>.d</file> directory
5331 corresponding to the new runlevel.) The <tt>K</tt> links
5332 are responsible for killing services and the <tt>S</tt>
5333 link for starting services upon entering the runlevel.
5337 For example, if we are changing from runlevel 2 to
5338 runlevel 3, init will first execute all of the <tt>K</tt>
5339 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
5340 all of the <tt>S</tt> prefixed scripts in that directory.
5341 The links starting with <tt>K</tt> will cause the
5342 referred-to file to be executed with an argument of
5343 <tt>stop</tt>, and the <tt>S</tt> links with an argument
5348 The two-digit number <var>mm</var> is used to determine
5349 the order in which to run the scripts: low-numbered links
5350 have their scripts run first. For example, the
5351 <tt>K20</tt> scripts will be executed before the
5352 <tt>K30</tt> scripts. This is used when a certain service
5353 must be started before another. For example, the name
5354 server <prgn>bind</prgn> might need to be started before
5355 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
5356 can set up its access lists. In this case, the script
5357 that starts <prgn>bind</prgn> would have a lower number
5358 than the script that starts <prgn>inn</prgn> so that it
5360 <example compact="compact">
5367 The two runlevels 0 (halt) and 6 (reboot) are slightly
5368 different. In these runlevels, the links with an
5369 <tt>S</tt> prefix are still called after those with a
5370 <tt>K</tt> prefix, but they too are called with the single
5371 argument <tt>stop</tt>.
5375 Also, if the script name ends <tt>.sh</tt>, the script
5376 will be sourced in runlevel <tt>S</tt> rather that being
5377 run in a forked subprocess, but will be explicitly run by
5378 <prgn>sh</prgn> in all other runlevels.
5383 <heading>Writing the scripts</heading>
5386 Packages that include daemons for system services should
5387 place scripts in <file>/etc/init.d</file> to start or stop
5388 services at boot time or during a change of runlevel.
5389 These scripts should be named
5390 <file>/etc/init.d/<var>package</var></file>, and they should
5391 accept one argument, saying what to do:
5394 <tag><tt>start</tt></tag>
5395 <item>start the service,</item>
5397 <tag><tt>stop</tt></tag>
5398 <item>stop the service,</item>
5400 <tag><tt>restart</tt></tag>
5401 <item>stop and restart the service if it's already running,
5402 otherwise start the service</item>
5404 <tag><tt>reload</tt></tag>
5405 <item><p>cause the configuration of the service to be
5406 reloaded without actually stopping and restarting
5409 <tag><tt>force-reload</tt></tag>
5410 <item>cause the configuration to be reloaded if the
5411 service supports this, otherwise restart the
5415 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
5416 <tt>force-reload</tt> options should be supported by all
5417 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
5422 The <file>init.d</file> scripts should ensure that they will
5423 behave sensibly if invoked with <tt>start</tt> when the
5424 service is already running, or with <tt>stop</tt> when it
5425 isn't, and that they don't kill unfortunately-named user
5426 processes. The best way to achieve this is usually to use
5427 <prgn>start-stop-daemon</prgn>.
5431 If a service reloads its configuration automatically (as
5432 in the case of <prgn>cron</prgn>, for example), the
5433 <tt>reload</tt> option of the <file>init.d</file> script
5434 should behave as if the configuration has been reloaded
5439 The <file>/etc/init.d</file> scripts must be treated as
5440 configuration files, either (if they are present in the
5441 package, that is, in the .deb file) by marking them as
5442 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
5443 by managing them correctly in the maintainer scripts (see
5444 <ref id="config-files">). This is important since we want
5445 to give the local system administrator the chance to adapt
5446 the scripts to the local system, e.g., to disable a
5447 service without de-installing the package, or to specify
5448 some special command line options when starting a service,
5449 while making sure her changes aren't lost during the next
5454 These scripts should not fail obscurely when the
5455 configuration files remain but the package has been
5456 removed, as configuration files remain on the system after
5457 the package has been removed. Only when <prgn>dpkg</prgn>
5458 is executed with the <tt>--purge</tt> option will
5459 configuration files be removed. In particular, as the
5460 <file>/etc/init.d/<var>package</var></file> script itself is
5461 usually a <tt>conffile</tt>, it will remain on the system
5462 if the package is removed but not purged. Therefore, you
5463 should include a <tt>test</tt> statement at the top of the
5465 <example compact="compact">
5466 test -f <var>program-executed-later-in-script</var> || exit 0
5471 Often there are some variables in the <file>init.d</file>
5472 scripts whose values control the behaviour of the scripts,
5473 and which a system administrator is likely to want to
5474 change. As the scripts themselves are frequently
5475 <tt>conffile</tt>s, modifying them requires that the
5476 administrator merge in their changes each time the package
5477 is upgraded and the <tt>conffile</tt> changes. To ease
5478 the burden on the system administrator, such configurable
5479 values should not be placed directly in the script.
5480 Instead, they should be placed in a file in
5481 <file>/etc/default</file>, which typically will have the same
5482 base name as the <file>init.d</file> script. This extra file
5483 should be sourced by the script when the script runs. It
5484 must contain only variable settings and comments in POSIX
5485 <prgn>sh</prgn> format. It may either be a
5486 <tt>conffile</tt> or a configuration file maintained by
5487 the package maintainer scripts. See <ref id="config-files">
5492 To ensure that vital configurable values are always
5493 available, the <file>init.d</file> script should set default
5494 values for each of the shell variables it uses, either
5495 before sourcing the <file>/etc/default/</file> file or
5496 afterwards using something like the <tt>:
5497 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
5498 script must behave sensibly and not fail if the
5499 <file>/etc/default</file> file is deleted.
5504 <heading>Interfacing with the initscript system</heading>
5507 Maintainers should use the abstraction layer provided by
5508 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
5509 programs to deal with initscripts in their packages'
5510 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
5511 and <prgn>postrm</prgn>.
5515 Directly managing the /etc/rc?.d links and directly
5516 invoking the <file>/etc/init.d/</file> initscripts should
5517 be done only by packages providing the initscript
5518 subsystem (such as <prgn>sysvinit</prgn> and
5519 <prgn>file-rc</prgn>).
5523 <heading>Managing the links</heading>
5526 The program <prgn>update-rc.d</prgn> is provided for
5527 package maintainers to arrange for the proper creation and
5528 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
5529 or their functional equivalent if another method is being
5530 used. This may be used by maintainers in their packages'
5531 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
5535 You must not include any <file>/etc/rc<var>n</var>.d</file>
5536 symbolic links in the actual archive or manually create or
5537 remove the symbolic links in maintainer scripts; you must
5538 use the <prgn>update-rc.d</prgn> program instead. (The
5539 former will fail if an alternative method of maintaining
5540 runlevel information is being used.) You must not include
5541 the <file>/etc/rc<var>n</var>.d</file> directories themselves
5542 in the archive either. (Only the <tt>sysvinit</tt>
5547 By default <prgn>update-rc.d</prgn> will start services in
5548 each of the multi-user state runlevels (2, 3, 4, and 5)
5549 and stop them in the halt runlevel (0), the single-user
5550 runlevel (1) and the reboot runlevel (6). The system
5551 administrator will have the opportunity to customize
5552 runlevels by simply adding, moving, or removing the
5553 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
5554 symbolic links are being used, or by modifying
5555 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
5560 To get the default behavior for your package, put in your
5561 <prgn>postinst</prgn> script
5562 <example compact="compact">
5563 update-rc.d <var>package</var> defaults
5565 and in your <prgn>postrm</prgn>
5566 <example compact="compact">
5567 if [ "$1" = purge ]; then
5568 update-rc.d <var>package</var> remove
5570 </example>. Note that if your package changes runlevels
5571 or priority, you may have to remove and recreate the links,
5572 since otherwise the old links may persist. Refer to the
5573 documentation of <prgn>update-rc.d</prgn>.
5577 This will use a default sequence number of 20. If it does
5578 not matter when or in which order the <file>init.d</file>
5579 script is run, use this default. If it does, then you
5580 should talk to the maintainer of the <prgn>sysvinit</prgn>
5581 package or post to <tt>debian-devel</tt>, and they will
5582 help you choose a number.
5586 For more information about using <tt>update-rc.d</tt>,
5587 please consult its manpage <manref name="update-rc.d"
5593 <heading>Running initscripts</heading>
5595 The program <prgn>invoke-rc.d</prgn> is provided to make
5596 it easier for package maintainers to properly invoke an
5597 initscript, obeying runlevel and other locally-defined
5598 constraints that might limit a package's right to start,
5599 stop and otherwise manage services. This program may be
5600 used by maintainers in their packages' scripts.
5604 The use of <prgn>invoke-rc.d</prgn> to invoke the
5605 <file>/etc/init.d/*</file> initscripts is strongly
5606 recommended<footnote>
5607 In the future, the use of invoke-rc.d to invoke
5608 initscripts shall be made mandatory. Maintainers are
5609 advised to switch to invoke-rc.d as soon as
5611 </footnote>, instead of calling them directly.
5615 By default, <prgn>invoke-rc.d</prgn> will pass any
5616 action requests (start, stop, reload, restart...) to the
5617 <file>/etc/init.d</file> script, filtering out requests
5618 to start or restart a service out of its intended
5623 Most packages will simply need to change:
5624 <example compact="compact">/etc/init.d/<package>
5625 <action></example> in their <prgn>postinst</prgn>
5626 and <prgn>prerm</prgn> scripts to:
5627 <example compact="compact">
5628 if [ -x /usr/sbin/invoke-rc.d ] ; then
5629 invoke-rc.d <var>package</var> <action>
5631 /etc/init.d/<var>package</var> <action>
5637 A package should register its initscript services using
5638 <prgn>update-rc.d</prgn> before it tries to invoke them
5639 using <prgn>invoke-rc.d</prgn>. Invocation of
5640 unregistered services may fail.
5644 For more information about using
5645 <prgn>invoke-rc.d</prgn>, please consult its manpage
5646 <manref name="invoke-rc.d" section="8">.
5652 <heading>Boot-time initialization</heading>
5655 There used to be another directory, <file>/etc/rc.boot</file>,
5656 which contained scripts which were run once per machine
5657 boot. This has been deprecated in favour of links from
5658 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
5659 described in <ref id="/etc/init.d">. Packages must not
5660 place files in <file>/etc/rc.boot</file>.
5665 <heading>Example</heading>
5668 The <prgn>bind</prgn> DNS (nameserver) package wants to
5669 make sure that the nameserver is running in multiuser
5670 runlevels, and is properly shut down with the system. It
5671 puts a script in <file>/etc/init.d</file>, naming the script
5672 appropriately <tt>bind</tt>. As you can see, the script
5673 interprets the argument <tt>reload</tt> to send the
5674 nameserver a <tt>HUP</tt> signal (causing it to reload its
5675 configuration); this way the system administrator can say
5676 <tt>/etc/init.d/bind reload</tt> to reload the name
5677 server. The script has one configurable value, which can
5678 be used to pass parameters to the named program at
5679 startup; this value is read from
5680 <file>/etc/default/bind</file> (see below).
5684 <example compact="compact">
5687 # Original version by Robert Leslie
5688 # <rob@mars.org>, edited by iwj and cs
5690 test -x /usr/sbin/named || exit 0
5692 # Source defaults file.
5694 if [ -f /etc/default/bind ]; then
5701 echo -n "Starting domain name service: named"
5702 start-stop-daemon --start --quiet --exec /usr/sbin/named \
5707 echo -n "Stopping domain name service: named"
5708 start-stop-daemon --stop --quiet \
5709 --pidfile /var/run/named.pid --exec /usr/sbin/named
5713 echo -n "Restarting domain name service: named"
5714 start-stop-daemon --stop --quiet \
5715 --pidfile /var/run/named.pid --exec /usr/sbin/named
5716 start-stop-daemon --start --verbose --exec /usr/sbin/named \
5720 force-reload|reload)
5721 echo -n "Reloading configuration of domain name service: named"
5722 start-stop-daemon --stop --signal 1 --quiet \
5723 --pidfile /var/run/named.pid --exec /usr/sbin/named
5727 echo "Usage: /etc/init.d/bind " \
5728 " {start|stop|restart|reload|force-reload}" >&2
5738 Complementing the above init script is a configuration
5739 file <file>/etc/default/bind</file>, which contains
5740 configurable parameters used by the script. This would be
5741 created by the <prgn>postinst</prgn> script if it was not
5742 already present, and removed on purge by the
5743 <prgn>postrm</prgn> script.
5744 <example compact="compact">
5745 # Specified parameters to pass to named. See named(8).
5746 # You may uncomment the following line, and edit to taste.
5752 Another example on which you can base your
5753 <file>/etc/init.d</file> scripts is found in
5754 <file>/etc/init.d/skeleton</file>.
5758 If this package is happy with the default setup from
5759 <prgn>update-rc.d</prgn>, namely an ordering number of 20
5760 and having named running in all runlevels, it can say in
5761 its <prgn>postinst</prgn>:
5762 <example compact="compact">
5763 update-rc.d bind defaults >/dev/null
5765 And in its <prgn>postrm</prgn>, to remove the links when the
5767 <example compact="compact">
5768 if [ "$1" = purge ]; then
5769 update-rc.d bind remove >/dev/null
5777 <heading>Console messages from <file>init.d</file> scripts</heading>
5780 This section describes the formats to be used for messages
5781 written to standard output by the <file>/etc/init.d</file>
5782 scripts. The intent is to improve the consistency of
5783 Debian's startup and shutdown look and feel. For this
5784 reason, please look very carefully at the details. We want
5785 the messages to have the same format in terms of wording,
5786 spaces, punctuation and case of letters.
5790 Here is a list of overall rules that you should use when you
5791 create output messages. They can be useful if you have a
5792 non-standard message that is not covered specifically in the
5799 Every message should fit in one line (fewer than 80
5800 characters), start with a capital letter and end with
5801 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
5805 If you want to express that the computer is working on
5806 something (that is, performing a specific task, not
5807 starting or stopping a program), we use an "ellipsis"
5808 (three dots: <tt>...</tt>). Note that we don't insert
5809 spaces before or after the dots. If the task has been
5810 completed we write <tt>done.</tt> and a line feed.
5814 Design your messages as if the computer is telling you
5815 what he is doing (let him be polite :-), but don't
5816 mention "him" directly. For example, if you think of
5818 <example compact="compact">
5819 I'm starting network daemons: nfsd mountd.
5822 <example compact="compact">
5823 Starting network daemons: nfsd mountd.
5830 There are standard message formats for the following
5831 situations. They should be used by the <tt>init.d</tt>
5838 <p>When daemons are started</p>
5841 If your script starts one or more daemons, the output
5842 should look like this (a single line, no leading
5844 <example compact="compact">
5845 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
5847 The <var>description</var> should describe the
5848 subsystem the daemon or set of daemons are part of,
5849 while <var>daemon-1</var> up to <var>daemon-n</var>
5850 denote each daemon's name (typically the file name of
5855 For example, the output of <file>/etc/init.d/lpd</file>
5857 <example compact="compact">
5858 Starting printer spooler: lpd.
5863 This can be achieved by saying
5864 <example compact="compact">
5865 echo -n "Starting printer spooler: lpd"
5866 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
5869 in the script. If you have more than one daemon to
5870 start, you should do the following:
5871 <example compact="compact">
5872 echo -n "Starting remote file system services:"
5873 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
5874 echo -n " mountd"; start-stop-daemon --start --quiet mountd
5875 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
5878 This makes it possible for the user to see what takes
5879 so long and when the final daemon has been started.
5880 You should be careful where to put spaces: in the
5881 example above the system administrator can easily
5882 comment out a line if he don't wants to start a
5883 specific daemon, while the displayed message still
5889 <p>When a system parameter is being set</p>
5892 If you have to set up different system parameters
5893 during the system boot, you should use this format:
5894 <example compact="compact">
5895 Setting <var>parameter</var> to "<var>value</var>".
5900 You can use a statement such as the following to get
5902 <example compact="compact">
5903 echo "Setting DNS domainname to \"$domainname\"."
5908 Note that the same symbol (<tt>"</tt>) is used for the left
5909 and right quotation marks. A grave accent (<tt>`</tt>) is
5910 not a quote character; neither is an apostrophe
5916 <p>When a daemon is stopped or restarted</p>
5919 When you stop or restart a daemon, you should issue a
5920 message identical to the startup message, except that
5921 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
5922 or <tt>Restarting</tt> respectively.
5926 For example, stopping the printer daemon will like
5928 <example compact="compact">
5929 Stopping printer spooler: lpd.
5935 <p>When something is executed</p>
5938 There are several examples where you have to run a
5939 program at system startup or shutdown to perform a
5940 specific task, for example, setting the system's clock
5941 using <prgn>netdate</prgn> or killing all processes
5942 when the system shuts down. Your message should look
5944 <example compact="compact">
5945 Doing something very useful...done.
5947 You should print the <tt>done.</tt> immediately after
5948 the job has been completed, so that the user is
5949 informed why she has to wait. You can get this
5951 <example compact="compact">
5952 echo -n "Doing something very useful..."
5961 <p>When the configuration is reloaded</p>
5964 When a daemon is forced to reload its configuration
5965 files you should use the following format:
5966 <example compact="compact">
5967 Reloading <var>description</var> configuration...done.
5969 where <var>description</var> is the same as in the
5970 daemon starting message.
5978 <heading>Cron jobs</heading>
5981 Packages must not modify the configuration file
5982 <file>/etc/crontab</file>, and they must not modify the files in
5983 <file>/var/spool/cron/crontabs</file>.</p>
5986 If a package wants to install a job that has to be executed
5987 via cron, it should place a file with the name of the
5988 package in one or more of the following directories:
5989 <example compact="compact">
5994 As these directory names imply, the files within them are
5995 executed on a daily, weekly, or monthly basis,
5996 respectively. The exact times are listed in
5997 <file>/etc/crontab</file>.</p>
6000 All files installed in any of these directories must be
6001 scripts (e.g., shell scripts or Perl scripts) so that they
6002 can easily be modified by the local system administrator.
6003 In addition, they should be treated as configuration
6008 If a certain job has to be executed more frequently than
6009 daily, the package should install a file
6010 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6011 same syntax as <file>/etc/crontab</file> and is processed by
6012 <prgn>cron</prgn> automatically. The file must also be
6013 treated as a configuration file. (Note that entries in the
6014 <file>/etc/cron.d</file> directory are not handled by
6015 <prgn>anacron</prgn>. Thus, you should only use this
6016 directory for jobs which may be skipped if the system is not
6020 The scripts or crontab entries in these directories should
6021 check if all necessary programs are installed before they
6022 try to execute them. Otherwise, problems will arise when a
6023 package was removed but not purged since configuration files
6024 are kept on the system in this situation.</p>
6028 <heading>Menus</heading>
6031 The Debian <tt>menu</tt> package provides a standard
6032 interface between packages providing applications and
6033 documents, and <em>menu programs</em> (either X window
6034 managers or text-based menu programs such as
6035 <prgn>pdmenu</prgn>).
6039 All packages that provide applications that need not be
6040 passed any special command line arguments for normal
6041 operation should register a menu entry for those
6042 applications, so that users of the <tt>menu</tt> package
6043 will automatically get menu entries in their window
6044 managers, as well in shells like <tt>pdmenu</tt>.
6048 Menu entries should follow the current menu policy.
6052 The menu policy can be found in the <tt>menu-policy</tt>
6053 files in the <tt>debian-policy</tt> package.
6054 It is also available from the Debian web mirrors at
6055 <tt><url name="/doc/packaging-manuals/menu-policy/"
6056 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>
6057 and from the Debian archive mirrors at
6058 <tt><url name="/doc/package-developer/menu-policy.txt.gz"
6059 id="http://ftp.debian.org/debian/doc/package-developer/menu-policy.txt.gz"></tt>.
6063 Please also refer to the <em>Debian Menu System</em>
6064 documentation that comes with the <tt>menu</tt> package for
6065 information about how to register your applications and web
6071 <heading>Multimedia handlers</heading>
6074 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6075 is a mechanism for encoding files and data streams and
6076 providing meta-information about them, in particular their
6077 type (e.g. audio or video) and format (e.g. PNG, HTML,
6082 Registration of MIME type handlers allows programs like mail
6083 user agents and web browsers to invoke these handlers to
6084 view, edit or display MIME types they don't support directly.
6088 Packages which provide the ability to view/show/play,
6089 compose, edit or print MIME types should register themselves
6090 as such following the current MIME support policy.
6094 The MIME support policy can be found in the <tt>mime-policy</tt>
6095 files in the <tt>debian-policy</tt> package.
6096 It is also available from the Debian web mirrors at
6097 <tt><url name="/doc/packaging-manuals/mime-policy/"
6098 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>
6099 and from the Debian archive mirrors at
6100 <tt><url name="/doc/package-developer/mime-policy.txt.gz"
6101 id="http://ftp.debian.org/debian/doc/package-developer/mime-policy.txt.gz"></tt>.
6107 <heading>Keyboard configuration</heading>
6110 To achieve a consistent keyboard configuration so that all
6111 applications interpret a keyboard event the same way, all
6112 programs in the Debian distribution must be configured to
6113 comply with the following guidelines.
6117 The following keys must have the specified interpretations:
6120 <tag><tt><--</tt></tag>
6121 <item>delete the character to the left of the cursor</item>
6123 <tag><tt>Delete</tt></tag>
6124 <item>delete the character to the right of the cursor</item>
6126 <tag><tt>Control+H</tt></tag>
6127 <item>emacs: the help prefix</item>
6130 The interpretation of any keyboard events should be
6131 independent of the terminal that is used, be it a virtual
6132 console, an X terminal emulator, an rlogin/telnet session,
6137 The following list explains how the different programs
6138 should be set up to achieve this:
6144 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6148 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6152 X translations are set up to make
6153 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6154 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6155 is the vt220 escape code for the "delete character"
6156 key). This must be done by loading the X resources
6157 using <prgn>xrdb</prgn> on all local X displays, not
6158 using the application defaults, so that the
6159 translation resources used correspond to the
6160 <prgn>xmodmap</prgn> settings.
6164 The Linux console is configured to make
6165 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6166 generate <tt>ESC [ 3 ~</tt>.
6170 X applications are configured so that <tt><</tt>
6171 deletes left, and <tt>Delete</tt> deletes right. Motif
6172 applications already work like this.
6176 Terminals should have <tt>stty erase ^?</tt> .
6180 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6181 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6182 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6186 Emacs is programmed to map <tt>KB_Backspace</tt> or
6187 the <tt>stty erase</tt> character to
6188 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6189 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6190 <tt>^H</tt> to <tt>help</tt> as always.
6194 Other applications use the <tt>stty erase</tt>
6195 character and <tt>kdch1</tt> for the two delete keys,
6196 with ASCII DEL being "delete previous character" and
6197 <tt>kdch1</tt> being "delete character under
6205 This will solve the problem except for the following
6212 Some terminals have a <tt><--</tt> key that cannot
6213 be made to produce anything except <tt>^H</tt>. On
6214 these terminals Emacs help will be unavailable on
6215 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6216 character takes precedence in Emacs, and has been set
6217 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6218 available) can be used instead.
6222 Some operating systems use <tt>^H</tt> for <tt>stty
6223 erase</tt>. However, modern telnet versions and all
6224 rlogin versions propagate <tt>stty</tt> settings, and
6225 almost all UNIX versions honour <tt>stty erase</tt>.
6226 Where the <tt>stty</tt> settings are not propagated
6227 correctly, things can be made to work by using
6228 <tt>stty</tt> manually.
6232 Some systems (including previous Debian versions) use
6233 <prgn>xmodmap</prgn> to arrange for both
6234 <tt><--</tt> and <tt>Delete</tt> to generate
6235 <tt>KB_Delete</tt>. We can change the behavior of
6236 their X clients using the same X resources that we use
6237 to do it for our own clients, or configure our clients
6238 using their resources when things are the other way
6239 around. On displays configured like this
6240 <tt>Delete</tt> will not work, but <tt><--</tt>
6245 Some operating systems have different <tt>kdch1</tt>
6246 settings in their <tt>terminfo</tt> database for
6247 <tt>xterm</tt> and others. On these systems the
6248 <tt>Delete</tt> key will not work correctly when you
6249 log in from a system conforming to our policy, but
6250 <tt><--</tt> will.
6257 <heading>Environment variables</heading>
6260 A program must not depend on environment variables to get
6261 reasonable defaults. (That's because these environment
6262 variables would have to be set in a system-wide
6263 configuration file like <file>/etc/profile</file>, which is not
6264 supported by all shells.)
6268 If a program usually depends on environment variables for its
6269 configuration, the program should be changed to fall back to
6270 a reasonable default configuration if these environment
6271 variables are not present. If this cannot be done easily
6272 (e.g., if the source code of a non-free program is not
6273 available), the program must be replaced by a small
6274 "wrapper" shell script which sets the environment variables
6275 if they are not already defined, and calls the original program.
6279 Here is an example of a wrapper script for this purpose:
6281 <example compact="compact">
6283 BAR=${BAR:-/var/lib/fubar}
6285 exec /usr/lib/foo/foo "$@"
6290 Furthermore, as <file>/etc/profile</file> is a configuration
6291 file of the <prgn>base-files</prgn> package, other packages must
6292 not put any environment variables or other commands into that
6301 <heading>Files</heading>
6304 <heading>Binaries</heading>
6307 Two different packages must not install programs with
6308 different functionality but with the same filenames. (The
6309 case of two programs having the same functionality but
6310 different implementations is handled via "alternatives" or
6311 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6312 <ref id="conflicts"> respectively.) If this case happens,
6313 one of the programs must be renamed. The maintainers should
6314 report this to the <tt>debian-devel</tt> mailing list and
6315 try to find a consensus about which program will have to be
6316 renamed. If a consensus cannot be reached, <em>both</em>
6317 programs must be renamed.
6321 By default, when a package is being built, any binaries
6322 created should include debugging information, as well as
6323 being compiled with optimization. You should also turn on
6324 as many reasonable compilation warnings as possible; this
6325 makes life easier for porters, who can then look at build
6326 logs for possible problems. For the C programming language,
6327 this means the following compilation parameters should be
6329 <example compact="compact">
6331 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6333 install -s # (or use strip on the files in debian/tmp)
6338 Note that by default all installed binaries should be stripped,
6339 either by using the <tt>-s</tt> flag to
6340 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6341 the binaries after they have been copied into
6342 <file>debian/tmp</file> but before the tree is made into a
6347 Although binaries in the build tree should be compiled with
6348 debugging information by default, it can often be difficult
6349 to debug programs if they are also subjected to compiler
6350 optimization. For this reason, it is recommended to support
6351 the standardized environment
6352 variable <tt>DEB_BUILD_OPTIONS</tt>. This variable can
6353 contain several flags to change how a package is compiled
6361 The presence of this string means that the package
6362 should be compiled with a minimum of optimization.
6363 For C programs, it is best to add <tt>-O0</tt>
6364 to <tt>CFLAGS</tt> (although this is usually the
6365 default). Some programs might fail to build or run at
6366 this level of optimization; it may be necessary to
6367 use <tt>-O1</tt>, for example.
6371 This string means that the debugging symbols should
6372 not be stripped from the binary during installation,
6373 so that debugging information may be included in the package.
6379 The following makefile snippet is an example of how one may
6380 implement the build options; you will probably have to
6381 massage this example in order to make it work for your
6383 <example compact="compact">
6386 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
6387 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
6388 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
6389 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
6391 ifneq (,$(findstring noopt,$(DEB_BUILD_OPTIONS)))
6396 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
6397 INSTALL_PROGRAM += -s
6403 It is up to the package maintainer to decide what
6404 compilation options are best for the package. Certain
6405 binaries (such as computationally-intensive programs) will
6406 function better with certain flags (<tt>-O3</tt>, for
6407 example); feel free to use them. Please use good judgment
6408 here. Don't use flags for the sake of it; only use them
6409 if there is good reason to do so. Feel free to override
6410 the upstream author's ideas about which compilation
6411 options are best: they are often inappropriate for our
6417 <sect id="libraries">
6418 <heading>Libraries</heading>
6421 The shared version of a library must be compiled with
6422 <tt>-fPIC</tt>, and the static version must not be. In other
6423 words, each source unit (<tt>*.c</tt>, for example, for C files)
6424 will need to be compiled twice.
6428 You must specify the gcc option <tt>-D_REENTRANT</tt>
6429 when building a library (either static or shared) to make
6430 the library compatible with LinuxThreads.
6435 Although not enforced by the build tools, shared libraries
6436 must be linked against all libraries that they use symbols from
6437 in the same way that binaries are. This ensures the correct
6438 functioning of the <ref id="sharedlibs-shlibdeps">shlibs</ref>
6439 system and guarantees that all libraries can be safely opened
6440 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
6441 option <tt>-Wl,-z,defs</tt> when building a shared library.
6442 Since this option enforces symbol resolution at build time,
6443 a missing library reference will be caught early as a fatal
6450 All installed shared libraries should be stripped with
6451 <example compact="compact">
6452 strip --strip-unneeded <var>your-lib</var>
6454 (The option <tt>--strip-unneeded</tt> makes
6455 <prgn>strip</prgn> remove only the symbols which aren't
6456 needed for relocation processing.) Shared libraries can
6457 function perfectly well when stripped, since the symbols for
6458 dynamic linking are in a separate part of the ELF object
6460 You might also want to use the options
6461 <tt>--remove-section=.comment</tt> and
6462 <tt>--remove-section=.note</tt> on both shared libraries
6463 and executables, and <tt>--strip-debug</tt> on static
6469 Note that under some circumstances it may be useful to
6470 install a shared library unstripped, for example when
6471 building a separate package to support debugging.
6475 Shared object files (often <file>.so</file> files) that are not
6476 public libraries, that is, they are not meant to be linked
6477 to by third party executables (binaries of other packages),
6478 should be installed in subdirectories of the
6479 <file>/usr/lib</file> directory. Such files are exempt from the
6480 rules that govern ordinary shared libraries, except that
6481 they must not be installed executable and should be
6483 A common example are the so-called "plug-ins",
6484 internal shared objects that are dynamically loaded by
6485 programs using <manref name="dlopen" section="3">.
6490 Packages containing shared libraries that may be linked to
6491 by other packages' binaries, but which for some
6492 <em>compelling</em> reason can not be installed in
6493 <file>/usr/lib</file> directory, may install the shared library
6494 files in subdirectories of the <file>/usr/lib</file> directory,
6495 in which case they should arrange to add that directory in
6496 <file>/etc/ld.so.conf</file> in the package's post-installation
6497 script, and remove it in the package's post-removal script.
6501 An ever increasing number of packages are using
6502 <prgn>libtool</prgn> to do their linking. The latest GNU
6503 libtools (>= 1.3a) can take advantage of the metadata in the
6504 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
6505 files). The main advantage of <prgn>libtool</prgn>'s
6506 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
6507 store and subsequently access metadata with respect to the
6508 libraries it builds. <prgn>libtool</prgn> will search for
6509 those files, which contain a lot of useful information about
6510 a library (such as library dependency information for static
6511 linking). Also, they're <em>essential</em> for programs
6512 using <tt>libltdl</tt>.<footnote>
6513 Although <prgn>libtool</prgn> is fully capable of
6514 linking against shared libraries which don't have
6515 <tt>.la</tt> files, as it is a mere shell script it can
6516 add considerably to the build time of a
6517 <prgn>libtool</prgn>-using package if that shell script
6518 has to derive all this information from first principles
6519 for each library every time it is linked. With the
6520 advent of <prgn>libtool</prgn> version 1.4 (and to a
6521 lesser extent <prgn>libtool</prgn> version 1.3), the
6522 <file>.la</file> files also store information about
6523 inter-library dependencies which cannot necessarily be
6524 derived after the <file>.la</file> file is deleted.
6529 Packages that use <prgn>libtool</prgn> to create shared
6530 libraries should include the <file>.la</file> files in the
6531 <tt>-dev</tt> package, unless the package relies on
6532 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
6533 the <tt>.la</tt> files must go in the run-time library
6538 You must make sure that you use only released versions of
6539 shared libraries to build your packages; otherwise other
6540 users will not be able to run your binaries
6541 properly. Producing source packages that depend on
6542 unreleased compilers is also usually a bad
6549 <heading>Shared libraries</heading>
6551 This section has moved to <ref id="sharedlibs">.
6557 <heading>Scripts</heading>
6560 All command scripts, including the package maintainer
6561 scripts inside the package and used by <prgn>dpkg</prgn>,
6562 should have a <tt>#!</tt> line naming the shell to be used
6567 In the case of Perl scripts this should be
6568 <tt>#!/usr/bin/perl</tt>.
6572 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
6573 should almost certainly start with <tt>set -e</tt> so that
6574 errors are detected. Every script should use
6575 <tt>set -e</tt> or check the exit status of <em>every</em>
6580 The standard shell interpreter <file>/bin/sh</file> can be a
6581 symbolic link to any POSIX compatible shell, if <tt>echo
6582 -n</tt> does not generate a newline.<footnote>
6583 Debian policy specifies POSIX behavior for
6584 <file>/bin/sh</file>, but <tt>echo -n</tt> has widespread
6585 use in the Linux community (in particular including this
6586 policy, the Linux kernel source, many Debian scripts,
6587 etc.). This <tt>echo -n</tt> mechanism is valid but not
6588 required under POSIX, hence this explicit addition.
6589 Also, rumour has it that this shall be mandated under
6592 Thus, shell scripts specifying <file>/bin/sh</file> as
6593 interpreter should only use POSIX features. If a script
6594 requires non-POSIX features from the shell interpreter, the
6595 appropriate shell must be specified in the first line of the
6596 script (e.g., <tt>#!/bin/bash</tt>) and the package must
6597 depend on the package providing the shell (unless the shell
6598 package is marked "Essential", as in the case of
6603 You may wish to restrict your script to POSIX features when
6604 possible so that it may use <file>/bin/sh</file> as its
6605 interpreter. If your script works with <prgn>dash</prgn>
6606 (originally called <prgn>ash</prgn>), it's probably POSIX
6607 compliant, but if you are in doubt, use
6608 <file>/bin/bash</file>.
6612 Perl scripts should check for errors when making any
6613 system calls, including <tt>open</tt>, <tt>print</tt>,
6614 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
6618 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
6619 scripting languages. See <em>Csh Programming Considered
6620 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
6621 can be found at <url id="http://language.perl.com/versus/csh.whynot">.
6622 If an upstream package comes with <prgn>csh</prgn> scripts
6623 then you must make sure that they start with
6624 <tt>#!/bin/csh</tt> and make your package depend on the
6625 <prgn>c-shell</prgn> virtual package.
6629 Any scripts which create files in world-writeable
6630 directories (e.g., in <file>/tmp</file>) must use a
6631 mechanism which will fail if a file with the same name
6636 The Debian base system provides the <prgn>tempfile</prgn>
6637 and <prgn>mktemp</prgn> utilities for use by scripts for
6644 <heading>Symbolic links</heading>
6647 In general, symbolic links within a top-level directory
6648 should be relative, and symbolic links pointing from one
6649 top-level directory into another should be absolute. (A
6650 top-level directory is a sub-directory of the root
6651 directory <file>/</file>.)
6655 In addition, symbolic links should be specified as short as
6656 possible, i.e., link targets like <file>foo/../bar</file> are
6661 Note that when creating a relative link using
6662 <prgn>ln</prgn> it is not necessary for the target of the
6663 link to exist relative to the working directory you're
6664 running <prgn>ln</prgn> from, nor is it necessary to change
6665 directory to the directory where the link is to be made.
6666 Simply include the string that should appear as the target
6667 of the link (this will be a pathname relative to the
6668 directory in which the link resides) as the first argument
6673 For example, in your <prgn>Makefile</prgn> or
6674 <file>debian/rules</file>, you can do things like:
6675 <example compact="compact">
6676 ln -fs gcc $(prefix)/bin/cc
6677 ln -fs gcc debian/tmp/usr/bin/cc
6678 ln -fs ../sbin/sendmail $(prefix)/bin/runq
6679 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
6684 A symbolic link pointing to a compressed file should always
6685 have the same file extension as the referenced file. (For
6686 example, if a file <file>foo.gz</file> is referenced by a
6687 symbolic link, the filename of the link has to end with
6688 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
6693 <heading>Device files</heading>
6696 Packages must not include device files in the package file
6701 If a package needs any special device files that are not
6702 included in the base system, it must call
6703 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
6704 after notifying the user<footnote>
6705 This notification could be done via a (low-priority)
6706 debconf message, or an echo (printf) statement.
6711 Packages must not remove any device files in the
6712 <prgn>postrm</prgn> or any other script. This is left to the
6713 system administrator.
6717 Debian uses the serial devices
6718 <file>/dev/ttyS*</file>. Programs using the old
6719 <file>/dev/cu*</file> devices should be changed to use
6720 <file>/dev/ttyS*</file>.
6724 <sect id="config-files">
6725 <heading>Configuration files</heading>
6728 <heading>Definitions</heading>
6732 <tag>configuration file</tag>
6734 A file that affects the operation of a program, or
6735 provides site- or host-specific information, or
6736 otherwise customizes the behavior of a program.
6737 Typically, configuration files are intended to be
6738 modified by the system administrator (if needed or
6739 desired) to conform to local policy or to provide
6740 more useful site-specific behavior.
6743 <tag><tt>conffile</tt></tag>
6745 A file listed in a package's <tt>conffiles</tt>
6746 file, and is treated specially by <prgn>dpkg</prgn>
6747 (see <ref id="configdetails">).
6753 The distinction between these two is important; they are
6754 not interchangeable concepts. Almost all
6755 <tt>conffile</tt>s are configuration files, but many
6756 configuration files are not <tt>conffiles</tt>.
6760 Note that a script that embeds configuration information
6761 (such as most of the files in <file>/etc/default</file> and
6762 <file>/etc/cron.{daily,weekly,monthly}</file>) is de-facto a
6763 configuration file and should be treated as such.
6768 <heading>Location</heading>
6771 Any configuration files created or used by your package
6772 must reside in <file>/etc</file>. If there are several,
6773 consider creating a subdirectory of <file>/etc</file>
6774 named after your package.
6778 If your package creates or uses configuration files
6779 outside of <file>/etc</file>, and it is not feasible to modify
6780 the package to use <file>/etc</file> directly, put the files
6781 in <file>/etc</file> and create symbolic links to those files
6782 from the location that the package requires.
6787 <heading>Behavior</heading>
6790 Configuration file handling must conform to the following
6792 <list compact="compact">
6794 local changes must be preserved during a package
6798 configuration files must be preserved when the
6799 package is removed, and only deleted when the
6806 The easy way to achieve this behavior is to make the
6807 configuration file a <tt>conffile</tt>. This is
6808 appropriate only if it is possible to distribute a default
6809 version that will work for most installations, although
6810 some system administrators may choose to modify it. This
6811 implies that the default version will be part of the
6812 package distribution, and must not be modified by the
6813 maintainer scripts during installation (or at any other
6818 In order to ensure that local changes are preserved
6819 correctly, no package may contain or make hard links to
6820 conffiles.<footnote>
6821 Rationale: There are two problems with hard links.
6822 The first is that some editors break the link while
6823 editing one of the files, so that the two files may
6824 unwittingly become unlinked and different. The second
6825 is that <prgn>dpkg</prgn> might break the hard link
6826 while upgrading <tt>conffile</tt>s.
6831 The other way to do it is via the maintainer scripts. In
6832 this case, the configuration file must not be listed as a
6833 <tt>conffile</tt> and must not be part of the package
6834 distribution. If the existence of a file is required for
6835 the package to be sensibly configured it is the
6836 responsibility of the package maintainer to provide
6837 maintainer scripts which correctly create, update and
6838 maintain the file and remove it on purge. (See <ref
6839 id="maintainerscripts"> for more information.) These
6840 scripts must be idempotent (i.e., must work correctly if
6841 <prgn>dpkg</prgn> needs to re-run them due to errors
6842 during installation or removal), must cope with all the
6843 variety of ways <prgn>dpkg</prgn> can call maintainer
6844 scripts, must not overwrite or otherwise mangle the user's
6845 configuration without asking, must not ask unnecessary
6846 questions (particularly during upgrades), and otherwise be
6851 The scripts are not required to configure every possible
6852 option for the package, but only those necessary to get
6853 the package running on a given system. Ideally the
6854 sysadmin should not have to do any configuration other
6855 than that done (semi-)automatically by the
6856 <prgn>postinst</prgn> script.
6860 A common practice is to create a script called
6861 <file><var>package</var>-configure</file> and have the
6862 package's <prgn>postinst</prgn> call it if and only if the
6863 configuration file does not already exist. In certain
6864 cases it is useful for there to be an example or template
6865 file which the maintainer scripts use. Such files should
6866 be in <file>/usr/share/<var>package</var></file> or
6867 <file>/usr/lib/<var>package</var></file> (depending on whether
6868 they are architecture-independent or not). There should
6869 be symbolic links to them from
6870 <file>/usr/share/doc/<var>package</var>/examples</file> if
6871 they are examples, and should be perfectly ordinary
6872 <prgn>dpkg</prgn>-handled files (<em>not</em>
6873 configuration files).
6877 These two styles of configuration file handling must
6878 not be mixed, for that way lies madness:
6879 <prgn>dpkg</prgn> will ask about overwriting the file
6880 every time the package is upgraded.
6885 <heading>Sharing configuration files</heading>
6888 Packages which specify the same file as a
6889 <tt>conffile</tt> must be tagged as <em>conflicting</em>
6890 with each other. (This is an instance of the general rule
6891 about not sharing files. Note that neither alternatives
6892 nor diversions are likely to be appropriate in this case;
6893 in particular, <prgn>dpkg</prgn> does not handle diverted
6894 <tt>conffile</tt>s well.)
6898 The maintainer scripts must not alter a <tt>conffile</tt>
6899 of <em>any</em> package, including the one the scripts
6904 If two or more packages use the same configuration file
6905 and it is reasonable for both to be installed at the same
6906 time, one of these packages must be defined as
6907 <em>owner</em> of the configuration file, i.e., it will be
6908 the package which handles that file as a configuration
6909 file. Other packages that use the configuration file must
6910 depend on the owning package if they require the
6911 configuration file to operate. If the other package will
6912 use the configuration file if present, but is capable of
6913 operating without it, no dependency need be declared.
6917 If it is desirable for two or more related packages to
6918 share a configuration file <em>and</em> for all of the
6919 related packages to be able to modify that configuration
6920 file, then the following should be done:
6921 <enumlist compact="compact">
6923 One of the related packages (the "owning" package)
6924 will manage the configuration file with maintainer
6925 scripts as described in the previous section.
6928 The owning package should also provide a program
6929 that the other packages may use to modify the
6933 The related packages must use the provided program
6934 to make any desired modifications to the
6935 configuration file. They should either depend on
6936 the core package to guarantee that the configuration
6937 modifier program is available or accept gracefully
6938 that they cannot modify the configuration file if it
6939 is not. (This is in addition to the fact that the
6940 configuration file may not even be present in the
6947 Sometimes it's appropriate to create a new package which
6948 provides the basic infrastructure for the other packages
6949 and which manages the shared configuration files. (The
6950 <tt>sgml-base</tt> package is a good example.)
6955 <heading>User configuration files ("dotfiles")</heading>
6958 The files in <file>/etc/skel</file> will automatically be
6959 copied into new user accounts by <prgn>adduser</prgn>.
6960 No other program should reference the files in
6961 <file>/etc/skel</file>.
6965 Therefore, if a program needs a dotfile to exist in
6966 advance in <file>$HOME</file> to work sensibly, that dotfile
6967 should be installed in <file>/etc/skel</file> and treated as a
6972 However, programs that require dotfiles in order to
6973 operate sensibly are a bad thing, unless they do create
6974 the dotfiles themselves automatically.
6978 Furthermore, programs should be configured by the Debian
6979 default installation to behave as closely to the upstream
6980 default behaviour as possible.
6984 Therefore, if a program in a Debian package needs to be
6985 configured in some way in order to operate sensibly, that
6986 should be done using a site-wide configuration file placed
6987 in <file>/etc</file>. Only if the program doesn't support a
6988 site-wide default configuration and the package maintainer
6989 doesn't have time to add it may a default per-user file be
6990 placed in <file>/etc/skel</file>.
6994 <file>/etc/skel</file> should be as empty as we can make it.
6995 This is particularly true because there is no easy (or
6996 necessarily desirable) mechanism for ensuring that the
6997 appropriate dotfiles are copied into the accounts of
6998 existing users when a package is installed.
7004 <heading>Log files</heading>
7006 Log files should usually be named
7007 <file>/var/log/<var>package</var>.log</file>. If you have many
7008 log files, or need a separate directory for permission
7009 reasons (<file>/var/log</file> is writable only by
7010 <file>root</file>), you should usually create a directory named
7011 <file>/var/log/<var>package</var></file> and place your log
7016 Log files must be rotated occasionally so that they don't
7017 grow indefinitely; the best way to do this is to drop a log
7018 rotation configuration file into the directory
7019 <file>/etc/logrotate.d</file> and use the facilities provided by
7020 logrotate.<footnote>
7022 The traditional approach to log files has been to set up
7023 <em>ad hoc</em> log rotation schemes using simple shell
7024 scripts and cron. While this approach is highly
7025 customizable, it requires quite a lot of sysadmin work.
7026 Even though the original Debian system helped a little
7027 by automatically installing a system which can be used
7028 as a template, this was deemed not enough.
7032 The use of <prgn>logrotate</prgn>, a program developed
7033 by Red Hat, is better, as it centralizes log management.
7034 It has both a configuration file
7035 (<file>/etc/logrotate.conf</file>) and a directory where
7036 packages can drop their individual log rotation
7037 configurations (<file>/etc/logrotate.d</file>).
7040 Here is a good example for a logrotate config
7041 file (for more information see <manref name="logrotate"
7043 <example compact="compact">
7044 /var/log/foo/*.log {
7049 /etc/init.d/foo force-reload
7053 This rotates all files under <file>/var/log/foo</file>, saves 12
7054 compressed generations, and forces the daemon to reload its
7055 configuration information after the log rotation.
7059 Log files should be removed when the package is
7060 purged (but not when it is only removed). This should be
7061 done by the <prgn>postrm</prgn> script when it is called
7062 with the argument <tt>purge</tt> (see <ref
7063 id="removedetails">).
7068 <heading>Permissions and owners</heading>
7071 The rules in this section are guidelines for general use.
7072 If necessary you may deviate from the details below.
7073 However, if you do so you must make sure that what is done
7074 is secure and you should try to be as consistent as possible
7075 with the rest of the system. You should probably also
7076 discuss it on <prgn>debian-devel</prgn> first.
7080 Files should be owned by <tt>root.root</tt>, and made
7081 writable only by the owner and universally readable (and
7082 executable, if appropriate), that is mode 644 or 755.
7086 Directories should be mode 755 or (for group-writability)
7087 mode 2775. The ownership of the directory should be
7088 consistent with its mode: if a directory is mode 2775, it
7089 should be owned by the group that needs write access to
7094 Setuid and setgid executables should be mode 4755 or 2755
7095 respectively, and owned by the appropriate user or group.
7096 They should not be made unreadable (modes like 4711 or
7097 2711 or even 4111); doing so achieves no extra security,
7098 because anyone can find the binary in the freely available
7099 Debian package; it is merely inconvenient. For the same
7100 reason you should not restrict read or execute permissions
7101 on non-set-id executables.
7105 Some setuid programs need to be restricted to particular
7106 sets of users, using file permissions. In this case they
7107 should be owned by the uid to which they are set-id, and by
7108 the group which should be allowed to execute them. They
7109 should have mode 4754; again there is no point in making
7110 them unreadable to those users who must not be allowed to
7115 It is possible to arrange that the system administrator can
7116 reconfigure the package to correspond to their local
7117 security policy by changing the permissions on a binary:
7118 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7119 described below.<footnote>
7120 Ordinary files installed by <prgn>dpkg</prgn> (as
7121 opposed to <tt>conffile</tt>s and other similar objects)
7122 normally have their permissions reset to the distributed
7123 permissions when the package is reinstalled. However,
7124 the use of <prgn>dpkg-statoverride</prgn> overrides this
7125 default behaviour. If you use this method, you should
7126 remember to describe <prgn>dpkg-statoverride</prgn> in
7127 the package documentation; being a relatively new
7128 addition to Debian, it is probably not yet well-known.
7130 Another method you should consider is to create a group for
7131 people allowed to use the program(s) and make any setuid
7132 executables executable only by that group.
7136 If you need to create a new user or group for your package
7137 there are two possibilities. Firstly, you may need to
7138 make some files in the binary package be owned by this
7139 user or group, or you may need to compile the user or
7140 group id (rather than just the name) into the binary
7141 (though this latter should be avoided if possible, as in
7142 this case you need a statically allocated id).</p>
7145 If you need a statically allocated id, you must ask for a
7146 user or group id from the <tt>base-passwd</tt> maintainer,
7147 and must not release the package until you have been
7148 allocated one. Once you have been allocated one you must
7149 either make the package depend on a version of the
7150 <tt>base-passwd</tt> package with the id present in
7151 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7152 your package to create the user or group itself with the
7153 correct id (using <tt>adduser</tt>) in its
7154 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7155 the <prgn>postinst</prgn> is to be preferred if it is
7156 possible, otherwise a pre-dependency will be needed on the
7157 <tt>adduser</tt> package.)
7161 On the other hand, the program might be able to determine
7162 the uid or gid from the user or group name at runtime, so
7163 that a dynamically allocated id can be used. In this case
7164 you should choose an appropriate user or group name,
7165 discussing this on <prgn>debian-devel</prgn> and checking
7166 with the <package/base-passwd/ maintainer that it is unique and that
7167 they do not wish you to use a statically allocated id
7168 instead. When this has been checked you must arrange for
7169 your package to create the user or group if necessary using
7170 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7171 <prgn>postinst</prgn> script (again, the latter is to be
7172 preferred if it is possible).
7176 Note that changing the numeric value of an id associated
7177 with a name is very difficult, and involves searching the
7178 file system for all appropriate files. You need to think
7179 carefully whether a static or dynamic id is required, since
7180 changing your mind later will cause problems.
7183 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7185 This section is not intended as policy, but as a
7186 description of the use of <prgn>dpkg-statoverride</prgn>.
7190 <prgn>dpkg-statoverride</prgn> is a replacement for the
7191 deprecated <tt>suidmanager</tt> package. Packages which
7192 previously used <tt>suidmanager</tt> should have a
7193 <tt>Conflicts: suidmanager (<< 0.50)</tt> entry (or even
7194 <tt>(<< 0.52)</tt>), and calls to <tt>suidregister</tt>
7195 and <tt>suidunregister</tt> should now be simply removed
7196 from the maintainer scripts.
7200 If a system administrator wishes to have a file (or
7201 directory or other such thing) installed with owner and
7202 permissions different from those in the distributed Debian
7203 package, he can use the <prgn>dpkg-statoverride</prgn>
7204 program to instruct <prgn>dpkg</prgn> to use the different
7205 settings every time the file is installed. Thus the
7206 package maintainer should distribute the files with their
7207 normal permissions, and leave it for the system
7208 administrator to make any desired changes. For example, a
7209 daemon which is normally required to be setuid root, but
7210 in certain situations could be used without being setuid,
7211 should be installed setuid in the <tt>.deb</tt>. Then the
7212 local system administrator can change this if they wish.
7213 If there are two standard ways of doing it, the package
7214 maintainer can use <tt>debconf</tt> to find out the
7215 preference, and call <prgn>dpkg-statoverride</prgn> in the
7216 maintainer script if necessary to accommodate the system
7217 administrator's choice.
7221 Given the above, <prgn>dpkg-statoverride</prgn> is
7222 essentially a tool for system administrators and would not
7223 normally be needed in the maintainer scripts. There is
7224 one type of situation, though, where calls to
7225 <prgn>dpkg-statoverride</prgn> would be needed in the
7226 maintainer scripts, and that involves packages which use
7227 dynamically allocated user or group ids. In such a
7228 situation, something like the following idiom can be very
7229 helpful in the package's <prgn>postinst</prgn>, where
7230 <tt>sysuser</tt> is a dynamically allocated id:
7232 for i in /usr/bin/foo /usr/sbin/bar
7234 if ! dpkg-statoverride --list $i >/dev/null
7236 dpkg-statoverride --update --add sysuser root 4755 $i
7240 The corresponding <tt>dpkg-statoverride --remove</tt>
7241 calls can then be made unconditionally when the package is
7249 <chapt id="customized-programs">
7250 <heading>Customized programs</heading>
7252 <sect id="arch-spec">
7253 <heading>Architecture specification strings</heading>
7256 If a program needs to specify an <em>architecture specification
7257 string</em> in some place, the following format should be
7258 used: <var>arch</var>-<var>os</var><footnote>
7259 The following architectures and operating systems are
7260 currently recognised by <prgn>dpkg-archictecture</prgn>.
7261 The architecture, <tt><var>arch</var></tt>, is one of
7262 the following: <tt>alpha</tt>, <tt>arm</tt>,
7263 <tt>hppa</tt>, <tt>i386</tt>, <tt>ia64</tt>,
7264 <tt>m68k</tt>, <tt>mips</tt>, <tt>mipsel</tt>,
7265 <tt>powerpc</tt>, <tt>s390</tt>, <tt>sh</tt>,
7266 <tt>sheb</tt>, <tt>sparc</tt> and <tt>sparc64</tt>. The
7267 operating system, <tt><var>os</var></tt>, is one of:
7268 <tt>linux</tt>, <tt>gnu</tt>, <tt>freebsd</tt> and
7269 <tt>openbsd</tt>. Use of <tt>gnu</tt> in this string is
7270 reserved for the GNU/Hurd operating system.
7275 Note that we don't want to use
7276 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7277 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7278 since this would make our programs incompatible with other
7279 Linux distributions. We also don't use something like
7280 <tt><var>arch</var>-unknown-linux</tt>, since the
7281 <tt>unknown</tt> does not look very good.
7286 <heading>Daemons</heading>
7289 The configuration files <file>/etc/services</file>,
7290 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7291 by the <prgn>netbase</prgn> package and must not be modified
7296 If a package requires a new entry in one of these files, the
7297 maintainer should get in contact with the
7298 <prgn>netbase</prgn> maintainer, who will add the entries
7299 and release a new version of the <prgn>netbase</prgn>
7304 The configuration file <file>/etc/inetd.conf</file> must not be
7305 modified by the package's scripts except via the
7306 <prgn>update-inetd</prgn> script or the
7307 <file>DebianNet.pm</file> Perl module. See their documentation
7308 for details on how to add entries.
7312 If a package wants to install an example entry into
7313 <file>/etc/inetd.conf</file>, the entry must be preceded with
7314 exactly one hash character (<tt>#</tt>). Such lines are
7315 treated as "commented out by user" by the
7316 <prgn>update-inetd</prgn> script and are not changed or
7317 activated during package updates.
7322 <heading>Using pseudo-ttys and modifying wtmp, utmp and
7326 Some programs need to create pseudo-ttys. This should be done
7327 using Unix98 ptys if the C library supports it. The resulting
7328 program must not be installed setuid root, unless that
7329 is required for other functionality.
7333 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
7334 <file>/var/log/lastlog</file> must be installed writeable by
7335 group <tt>utmp</tt>. Programs which need to modify those
7336 files must be installed setgid <tt>utmp</tt>.
7341 <heading>Editors and pagers</heading>
7344 Some programs have the ability to launch an editor or pager
7345 program to edit or display a text document. Since there are
7346 lots of different editors and pagers available in the Debian
7347 distribution, the system administrator and each user should
7348 have the possibility to choose his/her preferred editor and
7353 In addition, every program should choose a good default
7354 editor/pager if none is selected by the user or system
7359 Thus, every program that launches an editor or pager must
7360 use the EDITOR or PAGER environment variable to determine
7361 the editor or pager the user wishes to use. If these
7362 variables are not set, the programs <file>/usr/bin/editor</file>
7363 and <file>/usr/bin/pager</file> should be used, respectively.
7367 These two files are managed through the <prgn>dpkg</prgn>
7368 "alternatives" mechanism. Thus every package providing an
7369 editor or pager must call the
7370 <prgn>update-alternatives</prgn> script to register these
7375 If it is very hard to adapt a program to make use of the
7376 EDITOR or PAGER variables, that program may be configured to
7377 use <file>/usr/bin/sensible-editor</file> and
7378 <file>/usr/bin/sensible-pager</file> as the editor or pager
7379 program respectively. These are two scripts provided in the
7380 Debian base system that check the EDITOR and PAGER variables
7381 and launch the appropriate program, and fall back to
7382 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
7383 variable is not set.
7387 A program may also use the VISUAL environment variable to
7388 determine the user's choice of editor. If it exists, it
7389 should take precedence over EDITOR. This is in fact what
7390 <file>/usr/bin/sensible-editor</file> does.
7394 It is not required for a package to depend on
7395 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
7396 package to provide such virtual packages.<footnote>
7397 The Debian base system already provides an editor and a
7403 <sect id="web-appl">
7404 <heading>Web servers and applications</heading>
7407 This section describes the locations and URLs that should
7408 be used by all web servers and web applications in the
7415 Cgi-bin executable files are installed in the
7417 <example compact="compact">
7418 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
7420 and should be referred to as
7421 <example compact="compact">
7422 http://localhost/cgi-bin/<var>cgi-bin-name</var>
7427 <p>Access to HTML documents</p>
7430 HTML documents for a package are stored in
7431 <file>/usr/share/doc/<var>package</var></file>
7432 and can be referred to as
7433 <example compact="compact">
7434 http://localhost/doc/<var>package</var>/<var>filename</var>
7439 The web server should restrict access to the document
7440 tree so that only clients on the same host can read
7441 the documents. If the web server does not support such
7442 access controls, then it should not provide access at
7443 all, or ask about providing access during installation.
7448 <p>Web Document Root</p>
7451 Web Applications should try to avoid storing files in
7452 the Web Document Root. Instead they should use the
7453 /usr/share/doc/<var>package</var> directory for
7454 documents and register the Web Application via the
7455 menu package. If access to the web document root is
7456 unavoidable then use
7457 <example compact="compact">
7460 as the Document Root. This might be just a symbolic
7461 link to the location where the system administrator
7462 has put the real document root.
7470 <sect id="mail-transport-agents">
7471 <heading>Mail transport, delivery and user agents</heading>
7474 Debian packages which process electronic mail, whether mail
7475 user agents (MUAs) or mail transport agents (MTAs), must
7476 ensure that they are compatible with the configuration
7477 decisions below. Failure to do this may result in lost
7478 mail, broken <tt>From:</tt> lines, and other serious brain
7483 The mail spool is <file>/var/mail</file> and the interface to
7484 send a mail message is <file>/usr/sbin/sendmail</file> (as per
7485 the FHS). On older systems, the mail spool may be
7486 physically located in <file>/var/spool/mail</file>, but all
7487 access to the mail spool should be via the
7488 <file>/var/mail</file> symlink. The mail spool is part of the
7489 base system and not part of the MTA package.
7493 All Debian MUAs, MTAs, MDAs and other mailbox accessing
7494 programs (such as IMAP daemons) must lock the mailbox in an
7495 NFS-safe way. This means that <tt>fcntl()</tt> locking must
7496 be combined with dot locking. To avoid deadlocks, a program
7497 should use <tt>fcntl()</tt> first and dot locking after
7498 this, or alternatively implement the two locking methods in
7499 a non blocking way<footnote>
7500 If it is not possible to establish both locks, the
7501 system shouldn't wait for the second lock to be
7502 established, but remove the first lock, wait a (random)
7503 time, and start over locking again.
7504 </footnote>. Using the functions <tt>maillock</tt> and
7505 <tt>mailunlock</tt> provided by the
7506 <tt>liblockfile*</tt><footnote>
7507 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
7508 to use these functions.
7509 </footnote> packages is the recommended way to realize this.
7513 Mailboxes are generally mode 660
7514 <tt><var>user</var>.mail</tt> unless the system
7515 administrator has chosen otherwise. A MUA may remove a
7516 mailbox (unless it has nonstandard permissions) in which
7517 case the MTA or another MUA must recreate it if needed.
7518 Mailboxes must be writable by group mail.
7522 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
7523 be setgid mail to do the locking mentioned above (and
7524 must obviously avoid accessing other users' mailboxes
7525 using this privilege).</p>
7528 <file>/etc/aliases</file> is the source file for the system mail
7529 aliases (e.g., postmaster, usenet, etc.), it is the one
7530 which the sysadmin and <prgn>postinst</prgn> scripts may
7531 edit. After <file>/etc/aliases</file> is edited the program or
7532 human editing it must call <prgn>newaliases</prgn>. All MTA
7533 packages must come with a <prgn>newaliases</prgn> program,
7534 even if it does nothing, but older MTA packages did not do
7535 this so programs should not fail if <prgn>newaliases</prgn>
7536 cannot be found. Note that because of this, all MTA
7537 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
7538 <tt>Replaces: mail-transport-agent</tt> control file
7543 The convention of writing <tt>forward to
7544 <var>address</var></tt> in the mailbox itself is not
7545 supported. Use a <tt>.forward</tt> file instead.</p>
7548 The <prgn>rmail</prgn> program used by UUCP
7549 for incoming mail should be <file>/usr/sbin/rmail</file>.
7550 Likewise, <prgn>rsmtp</prgn>, for receiving
7551 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
7555 If your package needs to know what hostname to use on (for
7556 example) outgoing news and mail messages which are generated
7557 locally, you should use the file <file>/etc/mailname</file>. It
7558 will contain the portion after the username and <tt>@</tt>
7559 (at) sign for email addresses of users on the machine
7560 (followed by a newline).
7564 Such package should check for the existence of this file
7565 when it is being configured. If it exists, it should be
7566 used without comment, although an MTA's configuration script
7567 may wish to prompt the user even if it finds that this file
7568 exists. If the file does not exist, the package should
7569 prompt the user for the value (preferably using
7570 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
7571 as well as using it in the package's configuration. The
7572 prompt should make it clear that the name will not just be
7573 used by that package. For example, in this situation the
7574 <tt>inn</tt> package could say something like:
7575 <example compact="compact">
7576 Please enter the "mail name" of your system. This is the
7577 hostname portion of the address to be shown on outgoing
7578 news and mail messages. The default is
7579 <var>syshostname</var>, your system's host name. Mail
7580 name ["<var>syshostname</var>"]:
7582 where <var>syshostname</var> is the output of <tt>hostname
7588 <heading>News system configuration</heading>
7591 All the configuration files related to the NNTP (news)
7592 servers and clients should be located under
7593 <file>/etc/news</file>.</p>
7596 There are some configuration issues that apply to a number
7597 of news clients and server packages on the machine. These
7601 <tag><file>/etc/news/organization</file></tag>
7603 A string which should appear as the
7604 organization header for all messages posted
7605 by NNTP clients on the machine
7608 <tag><file>/etc/news/server</file></tag>
7610 Contains the FQDN of the upstream NNTP
7611 server, or localhost if the local machine is
7616 Other global files may be added as required for cross-package news
7623 <heading>Programs for the X Window System</heading>
7626 <heading>Providing X support and package priorities</heading>
7629 Programs that can be configured with support for the X
7630 Window System must be configured to do so and must declare
7631 any package dependencies necessary to satisfy their
7632 runtime requirements when using the X Window System. If
7633 such a package is of higher priority than the X packages
7634 on which it depends, it is required that either the
7635 X-specific components be split into a separate package, or
7636 that an alternative version of the package, which includes
7637 X support, be provided, or that the package's priority be
7643 <heading>Packages providing an X server</heading>
7646 Packages that provide an X server that, directly or
7647 indirectly, communicates with real input and display
7648 hardware should declare in their control data that they
7649 provide the virtual package <tt>xserver</tt>.<footnote>
7650 This implements current practice, and provides an
7651 actual policy for usage of the <tt>xserver</tt>
7652 virtual package which appears in the virtual packages
7653 list. In a nutshell, X servers that interface
7654 directly with the display and input hardware or via
7655 another subsystem (e.g., GGI) should provide
7656 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
7657 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
7663 <heading>Packages providing a terminal emulator</heading>
7666 Packages that provide a terminal emulator for the X Window
7667 System which meet the criteria listed below should declare
7668 in their control data that they provide the virtual
7669 package <tt>x-terminal-emulator</tt>. They should also
7670 register themselves as an alternative for
7671 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
7676 To be an <tt>x-terminal-emulator</tt>, a program must:
7677 <list compact="compact">
7679 Be able to emulate a DEC VT100 terminal, or a
7680 compatible terminal.
7684 Support the command-line option <tt>-e
7685 <var>command</var></tt>, which creates a new
7686 terminal window<footnote>
7687 "New terminal window" does not necessarily mean
7688 a new top-level X window directly parented by
7689 the window manager; it could, if the terminal
7690 emulator application were so coded, be a new
7691 "view" in a multiple-document interface (MDI).
7693 and runs the specified <var>command</var>,
7694 interpreting the entirity of the rest of the command
7695 line as a command to pass straight to exec, in the
7696 manner that <tt>xterm</tt> does.
7700 Support the command-line option <tt>-T
7701 <var>title</var></tt>, which creates a new terminal
7702 window with the window title <var>title</var>.
7709 <heading>Packages providing a window manager</heading>
7712 Packages that provide a window manager should declare in
7713 their control data that they provide the virtual package
7714 <tt>x-window-manager</tt>. They should also register
7715 themselves as an alternative for
7716 <file>/usr/bin/x-window-manager</file>, with a priority
7717 calculated as follows:
7718 <list compact="compact">
7720 Start with a priority of 20.
7724 If the window manager supports the Debian menu
7725 system, add 20 points if this support is available
7726 in the package's default configuration (i.e., no
7727 configuration files belonging to the system or user
7728 have to be edited to activate the feature); if
7729 configuration files must be modified, add only 10
7735 If the window manager complies with <url
7736 id="http://www.freedesktop.org/standards/wm-spec.html"
7737 name="The Window Manager Specification Project">,
7738 written by the <url id="http://www.freedesktop.org/"
7739 name="Free Desktop Group">, add 40 points.
7743 If the window manager permits the X session to be
7744 restarted using a <em>different</em> window manager
7745 (without killing the X server) in its default
7746 configuration, add 10 points; otherwise add none.
7753 <heading>Packages providing fonts</heading>
7756 Packages that provide fonts for the X Window
7758 For the purposes of Debian Policy, a "font for the X
7759 Window System" is one which is accessed via X protocol
7760 requests. Fonts for the Linux console, for PostScript
7761 renderers, or any other purpose, do not fit this
7762 definition. Any tool which makes such fonts available
7763 to the X Window System, however, must abide by this
7766 must do a number of things to ensure that they are both
7767 available without modification of the X or font server
7768 configuration, and that they do not corrupt files used by
7769 other font packages to register information about
7773 Fonts of any type supported by the X Window System
7774 must be in a separate binary package from any
7775 executables, libraries, or documentation (except
7776 that specific to the fonts shipped, such as their
7777 license information). If one or more of the fonts
7778 so packaged are necessary for proper operation of
7779 the package with which they are associated the font
7780 package may be Recommended; if the fonts merely
7781 provide an enhancement, a Suggests relationship may
7782 be used. Packages must not Depend on font
7784 This is because the X server may retrieve fonts
7785 from the local filesystem or over the network
7786 from an X font server; the Debian package system
7787 is empowered to deal only with the local
7793 BDF fonts must be converted to PCF fonts with the
7794 <prgn>bdftopcf</prgn> utility (available in the
7795 <tt>xutils</tt> package, <prgn>gzip</prgn>ped, and
7796 placed in a directory that corresponds to their
7798 <list compact="compact">
7800 100 dpi fonts must be placed in
7801 <file>/usr/X11R6/lib/X11/fonts/100dpi/</file>.
7805 75 dpi fonts must be placed in
7806 <file>/usr/X11R6/lib/X11/fonts/75dpi/</file>.
7810 Character-cell fonts, cursor fonts, and other
7811 low-resolution fonts must be placed in
7812 <file>/usr/X11R6/lib/X11/fonts/misc/</file>.
7818 Speedo fonts must be placed in
7819 <file>/usr/X11R6/lib/X11/fonts/Speedo/</file>.
7823 Type 1 fonts must be placed in
7824 <file>/usr/X11R6/lib/X11/fonts/Type1/</file>. If font
7825 metric files are available, they must be placed here
7830 Subdirectories of <file>/usr/X11R6/lib/X11/fonts/</file>
7831 other than those listed above must be neither
7832 created nor used. (The <file>PEX</file>, <file>CID</file>,
7833 and <file>cyrillic</file> directories are excepted for
7834 historical reasons, but installation of files into
7835 these directories remains discouraged.)
7839 Font packages may, instead of placing files directly
7840 in the X font directories listed above, provide
7841 symbolic links in that font directory pointing to
7842 the files' actual location in the filesystem. Such
7843 a location must comply with the FHS.
7847 Font packages should not contain both 75dpi and
7848 100dpi versions of a font. If both are available,
7849 they should be provided in separate binary packages
7850 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
7851 the names of the packages containing the
7852 corresponding fonts.
7856 Fonts destined for the <file>misc</file> subdirectory
7857 should not be included in the same package as 75dpi
7858 or 100dpi fonts; instead, they should be provided in
7859 a separate package with <tt>-misc</tt> appended to
7864 Font packages must not provide the files
7865 <file>fonts.dir</file>, <file>fonts.alias</file>, or
7866 <file>fonts.scale</file> in a font directory:
7869 <file>fonts.dir</file> files must not be provided at all.
7873 <file>fonts.alias</file> and <file>fonts.scale</file>
7874 files, if needed, should be provided in the
7876 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
7877 where <var>fontdir</var> is the name of the
7879 <file>/usr/X11R6/lib/X11/fonts/</file> where the
7880 package's corresponding fonts are stored
7881 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
7882 <var>package</var> is the name of the package
7883 that provides these fonts, and
7884 <var>extension</var> is either <tt>scale</tt>
7885 or <tt>alias</tt>, whichever corresponds to
7892 Font packages must declare a dependency on
7893 <tt>xutils (>> 4.0.3)</tt> in their control
7898 Font packages that provide one or more
7899 <file>fonts.scale</file> files as described above must
7900 invoke <prgn>update-fonts-scale</prgn> on each
7901 directory into which they installed fonts
7902 <em>before</em> invoking
7903 <prgn>update-fonts-dir</prgn> on that directory.
7904 This invocation must occur in both the
7905 <prgn>postinst</prgn> (for all arguments) and
7906 <prgn>postrm</prgn> (for all arguments except
7907 <tt>upgrade</tt>) scripts.
7911 Font packages that provide one or more
7912 <file>fonts.alias</file> files as described above must
7913 invoke <prgn>update-fonts-alias</prgn> on each
7914 directory into which they installed fonts. This
7915 invocation must occur in both the
7916 <prgn>postinst</prgn> (for all arguments) and
7917 <prgn>postrm</prgn> (for all arguments except
7918 <tt>upgrade</tt>) scripts.
7922 Font packages must invoke
7923 <prgn>update-fonts-dir</prgn> on each directory into
7924 which they installed fonts. This invocation must
7925 occur in both the <prgn>postinst</prgn> (for all
7926 arguments) and <prgn>postrm</prgn> (for all
7927 arguments except <tt>upgrade</tt>) scripts.
7931 Font packages must not provide alias names for the
7932 fonts they include which collide with alias names
7933 already in use by fonts already packaged.
7937 Font packages must not provide fonts with the same
7938 XLFD registry name as another font already packaged.
7945 <heading>Application defaults files</heading>
7948 Application defaults files must be installed in the
7949 directory <file>/etc/X11/app-defaults/</file> (use of a
7950 localized subdirectory of <file>/etc/X11/</file> as described
7951 in the <em>X Toolkit Intrinsics - C Language
7952 Interface</em> manual is also permitted). They must be
7953 registered as <tt>conffile</tt>s or handled as
7954 configuration files. Packages must not provide the
7955 directory <file>/usr/X11R6/lib/X11/app-defaults/</file>.
7959 Customization of programs' X resources may also be
7960 supported with the provision of a file with the same name
7961 as that of the package placed in the
7962 <file>/etc/X11/Xresources/</file> directory, which must
7963 registered as a <tt>conffile</tt> or handled as a
7964 configuration file.<footnote>
7965 Note that this mechanism is not the same as using
7966 app-defaults; app-defaults are tied to the client
7967 binary on the local filesystem, whereas X resources
7968 are stored in the X server and affect all connecting
7971 <em>Important:</em> packages that install files into the
7972 <file>/etc/X11/Xresources/</file> directory must conflict with
7973 <tt>xbase (<< 3.3.2.3a-2)</tt>; if this is not done
7974 it is possible for the installing package to destroy a
7975 previously-existing <file>/etc/X11/Xresources</file> file
7976 which had been customized by the system administrator.
7981 <heading>Installation directory issues</heading>
7984 Packages using the X Window System should not be
7985 configured to install files under the <file>/usr/X11R6/</file>
7986 directory unless they use <prgn>imake</prgn>. The
7987 <file>/usr/X11R6/</file> directory hierarchy should be
7988 regarded as deprecated for all packages except the X
7989 Window System itself, and those which use the
7990 <prgn>imake</prgn> program it provides, in which case the
7991 packages may transition out of the <file>/usr/X11R6/</file>
7992 directory at the maintainer's discretion.<footnote>
7993 <prgn>Imake</prgn>-using programs are exempt because,
7994 as long as they are written correctly, the pathnames
7995 they use to locate resources and install themselves
7996 are derived wholly from the X Window System
7997 configuration. Thus, in the event that the X Window
7998 System moves to <file>/usr/X11R7/</file>,
7999 <file>/usr/X12/</file>, or just plain <file>/usr/</file>, all
8000 that is required for these programs is a recompile
8001 against the corresponding X Window System library
8002 development packages.
8007 Programs that use GNU <prgn>autoconf</prgn> and
8008 <prgn>automake</prgn> are usually easily configured at
8009 compile time to use <file>/usr/</file> instead of
8010 <file>/usr/X11R6/</file>, and this should be done whenever
8011 possible. Configuration files for window managers and
8012 display managers should be placed in a subdirectory of
8013 <file>/etc/X11/</file> corresponding to the package name due
8014 to these programs' tight integration with the mechanisms
8015 of the X Window System. Application-level programs should
8016 use the <file>/etc/</file> directory unless otherwise mandated
8021 The installation of files into subdirectories
8022 of <file>/usr/X11R6/include/X11/</file> and
8023 <file>/usr/X11R6/lib/X11/</file> is permitted but discouraged;
8024 package maintainers should determine if subdirectories of
8025 <file>/usr/lib/</file> and <file>/usr/share/</file> can be used
8026 instead. (The use of symbolic links from the
8027 <file>X11R6</file> directories to other FHS-compliant
8028 locations is encouraged if the program is not easily
8029 configured to look elsewhere for its files.)
8033 Packages must not provide or install files into the directories
8034 <file>/usr/bin/X11/</file>, <file>/usr/include/X11/</file> or
8035 <file>/usr/lib/X11/</file>. Files within a package should,
8036 however, make reference to these directories, rather than
8037 their <tt>X11R6</tt>-named counterparts
8038 <file>/usr/X11R6/bin/</file>, <file>/usr/X11R6/include/X11/</file>
8039 and <file>/usr/X11R6/lib/X11/</file>, if the resources being
8040 referred to have not been moved to other FHS-compliant
8046 <heading>The OSF/Motif and OpenMotif libraries</heading>
8049 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8050 OpenMotif libraries</em><footnote>
8051 OSF/Motif and OpenMotif are collectively referred to as
8052 "Motif" in this policy document.
8054 should be compiled against and tested with LessTif (a free
8055 re-implementation of Motif) instead. If the maintainer
8056 judges that the program or programs do not work
8057 sufficiently well with LessTif to be distributed and
8058 supported, but do so when compiled against Motif, then two
8059 versions of the package should be created; one linked
8060 statically against Motif and with <tt>-smotif</tt>
8061 appended to the package name, and one linked dynamically
8062 against Motif and with <tt>-dmotif</tt> appended to the
8067 Both Motif-linked versions are dependent
8068 upon non-DFSG-compliant software and thus cannot be
8069 uploaded to the <em>main</em> distribution; if the
8070 software is itself DFSG-compliant it may be uploaded to
8071 the <em>contrib</em> distribution. While known existing
8072 versions of Motif permit unlimited redistribution of
8073 binaries linked against the library (whether statically or
8074 dynamically), it is the package maintainer's
8075 responsibility to determine whether this is permitted by
8076 the license of the copy of Motif in his or her possession.
8082 <heading>Perl programs and modules</heading>
8085 Perl programs and modules should follow the current Perl policy.
8089 The Perl policy can be found in the <tt>perl-policy</tt>
8090 files in the <tt>debian-policy</tt> package.
8091 It is also available from the Debian web mirrors at
8092 <tt><url name="/doc/packaging-manuals/perl-policy/"
8093 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>
8094 and from the Debian archive mirrors at
8095 <tt><url name="/doc/package-developer/perl-policy.txt.gz"
8096 id="http://ftp.debian.org/debian/doc/package-developer/perl-policy.txt.gz"></tt>.
8101 <heading>Emacs lisp programs</heading>
8104 Please refer to the "Debian Emacs Policy" for details of how to
8105 package emacs lisp programs.
8109 The Emacs policy is available in
8110 <file>debian-emacs-policy.gz</file> of the
8111 <package>emacsen-common</package> package.
8112 It is also available from the Debian web mirrors at
8113 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8114 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8119 <heading>Games</heading>
8122 The permissions on <file>/var/games</file> are mode 755, owner
8123 <tt>root</tt> and group <tt>root</tt>.
8127 Each game decides on its own security policy.</p>
8130 Games which require protected, privileged access to
8131 high-score files, savegames, etc., may be made
8132 set-<em>group</em>-id (mode 2755) and owned by
8133 <tt>root.games</tt>, and use files and directories with
8134 appropriate permissions (770 <tt>root.games</tt>, for
8135 example). They must not be made
8136 set-<em>user</em>-id, as this causes security problems. (If
8137 an attacker can subvert any set-user-id game they can
8138 overwrite the executable of any other, causing other players
8139 of these games to run a Trojan horse program. With a
8140 set-group-id game the attacker only gets access to less
8141 important game data, and if they can get at the other
8142 players' accounts at all it will take considerably more
8146 Some packages, for example some fortune cookie programs, are
8147 configured by the upstream authors to install with their
8148 data files or other static information made unreadable so
8149 that they can only be accessed through set-id programs
8150 provided. You should not do this in a Debian package: anyone can
8151 download the <file>.deb</file> file and read the data from it,
8152 so there is no point making the files unreadable. Not
8153 making the files unreadable also means that you don't have
8154 to make so many programs set-id, which reduces the risk of a
8158 As described in the FHS, binaries of games should be
8159 installed in the directory <file>/usr/games</file>. This also
8160 applies to games that use the X Window System. Manual pages
8161 for games (X and non-X games) should be installed in
8162 <file>/usr/share/man/man6</file>.</p>
8168 <heading>Documentation</heading>
8171 <heading>Manual pages</heading>
8174 You should install manual pages in <prgn>nroff</prgn> source
8175 form, in appropriate places under <file>/usr/share/man</file>.
8176 You should only use sections 1 to 9 (see the FHS for more
8177 details). You must not install a preformatted "cat page".
8181 Each program, utility, and function should have an
8182 associated manual page included in the same package. It is
8183 suggested that all configuration files also have a manual
8184 page included as well. Manual pages for protocols and other
8185 auxiliary things are optional.
8189 If no manual page is available, this is considered as a bug
8190 and should be reported to the Debian Bug Tracking System (the
8191 maintainer of the package is allowed to write this bug report
8192 themselves, if they so desire). Do not close the bug report
8193 until a proper manpage is available.<footnote>
8194 It is not very hard to write a man page. See the
8195 <url id="http://www.schweikhardt.net/man_page_howto.html"
8196 name="Man-Page-HOWTO">,
8197 <manref name="man" section="7">, the examples
8198 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8199 the helper programs <prgn>help2man</prgn>, or the
8200 directory <file>/usr/share/doc/man-db/examples</file>.
8205 You may forward a complaint about a missing manpage to the
8206 upstream authors, and mark the bug as forwarded in the
8207 Debian bug tracking system. Even though the GNU Project do
8208 not in general consider the lack of a manpage to be a bug,
8209 we do; if they tell you that they don't consider it a bug
8210 you should leave the bug in our bug tracking system open
8215 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8219 If one manpage needs to be accessible via several names it
8220 is better to use a symbolic link than the <file>.so</file>
8221 feature, but there is no need to fiddle with the relevant
8222 parts of the upstream source to change from <file>.so</file> to
8223 symlinks: don't do it unless it's easy. You should not
8224 create hard links in the manual page directories, nor put
8225 absolute filenames in <file>.so</file> directives. The filename
8226 in a <file>.so</file> in a manpage should be relative to the
8227 base of the manpage tree (usually
8228 <file>/usr/share/man</file>). If you do not create any links
8229 (whether symlinks, hard links, or <tt>.so</tt> directives)
8230 in the filesystem to the alternate names of the manpage,
8231 then you should not rely on <prgn>man</prgn> finding your
8232 manpage under those names based solely on the information in
8233 the manpage's header.<footnote>
8234 Supporting this in <prgn>man</prgn> often requires
8235 unreasonable processing time to find a manual page or to
8236 report that none exists, and moves knowledge into man's
8237 database that would be better left in the filesystem.
8238 This support is therefore deprecated and will cease to
8239 be present in the future.
8245 <heading>Info documents</heading>
8248 Info documents should be installed in <file>/usr/share/info</file>.
8249 They should be compressed with <tt>gzip -9</tt>.
8253 Your package should call <prgn>install-info</prgn> to update
8254 the Info <file>dir</file> file in its <prgn>postinst</prgn>
8255 script when called with a <tt>configure</tt> argument, for
8257 <example compact="compact">
8258 install-info --quiet --section Development Development \
8259 /usr/share/info/foobar.info
8263 It is a good idea to specify a section for the location of
8264 your program; this is done with the <tt>--section</tt>
8265 switch. To determine which section to use, you should look
8266 at <file>/usr/share/info/dir</file> on your system and choose the most
8267 relevant (or create a new section if none of the current
8268 sections are relevant). Note that the <tt>--section</tt>
8269 flag takes two arguments; the first is a regular expression
8270 to match (case-insensitively) against an existing section,
8271 the second is used when creating a new one.</p>
8274 You should remove the entries in the <prgn>prerm</prgn>
8275 script when called with a <tt>remove</tt> argument:
8276 <example compact="compact">
8277 install-info --quiet --remove /usr/share/info/foobar.info
8281 If <prgn>install-info</prgn> cannot find a description entry
8282 in the Info file you must supply one. See <manref
8283 name="install-info" section="8"> for details.</p>
8287 <heading>Additional documentation</heading>
8290 Any additional documentation that comes with the package may
8291 be installed at the discretion of the package maintainer.
8292 Text documentation should be installed in the directory
8293 <file>/usr/share/doc/<var>package</var></file>, where
8294 <var>package</var> is the name of the package, and
8295 compressed with <tt>gzip -9</tt> unless it is small.
8299 If a package comes with large amounts of documentation which
8300 many users of the package will not require you should create
8301 a separate binary package to contain it, so that it does not
8302 take up disk space on the machines of users who do not need
8303 or want it installed.</p>
8306 It is often a good idea to put text information files
8307 (<file>README</file>s, changelogs, and so forth) that come with
8308 the source package in <file>/usr/share/doc/<var>package</var></file>
8309 in the binary package. However, you don't need to install
8310 the instructions for building and installing the package, of
8314 Packages must not require the existence of any files in
8315 <file>/usr/share/doc/</file> in order to function
8317 The system administrator should be able to
8318 delete files in <file>/usr/share/doc/</file> without causing
8319 any programs to break.
8321 Any files that are referenced by programs but are also
8322 useful as standalone documentation should be installed under
8323 <file>/usr/share/<var>package</var>/</file> with symbolic links from
8324 <file>/usr/share/doc/<var>package</var></file>.
8328 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8329 link to another directory in <file>/usr/share/doc</file> only if
8330 the two packages both come from the same source and the
8331 first package Depends on the second.
8335 Former Debian releases placed all additional documentation
8336 in <file>/usr/doc/<var>package</var></file>. This has been
8337 changed to <file>/usr/share/doc/<var>package</var></file>,
8338 and packages must not put documentation in the directory
8339 <file>/usr/doc/<var>package</var></file>. <footnote>
8340 At this phase of the transition, we no longer require a
8341 symbolic link in <file>/usr/doc/</file>. At a later point,
8342 policy shall change to make the symbolic links a bug.
8348 <heading>Preferred documentation formats</heading>
8351 The unification of Debian documentation is being carried out
8355 If your package comes with extensive documentation in a
8356 markup format that can be converted to various other formats
8357 you should if possible ship HTML versions in a binary
8358 package, in the directory
8359 <file>/usr/share/doc/<var>appropriate-package</var></file> or
8360 its subdirectories.<footnote>
8361 The rationale: The important thing here is that HTML
8362 docs should be available in <em>some</em> package, not
8363 necessarily in the main binary package.
8368 Other formats such as PostScript may be provided at the
8369 package maintainer's discretion.
8373 <sect id="copyrightfile">
8374 <heading>Copyright information</heading>
8377 Every package must be accompanied by a verbatim copy of its
8378 copyright and distribution license in the file
8379 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
8380 file must neither be compressed nor be a symbolic link.
8384 In addition, the copyright file must say where the upstream
8385 sources (if any) were obtained. It should name the original
8386 authors of the package and the Debian maintainer(s) who were
8387 involved with its creation.</p>
8390 A copy of the file which will be installed in
8391 <file>/usr/share/doc/<var>package</var>/copyright</file> should
8392 be in <file>debian/copyright</file> in the source package.
8396 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8397 link to another directory in <file>/usr/share/doc</file> only if
8398 the two packages both come from the same source and the
8399 first package Depends on the second. These rules are
8400 important because copyrights must be extractable by
8405 Packages distributed under the UCB BSD license, the Artistic
8406 license, the GNU GPL, and the GNU LGPL should refer to the
8407 files <file>/usr/share/common-licenses/BSD</file>,
8408 <file>/usr/share/common-licenses/Artistic</file>,
8409 <file>/usr/share/common-licenses/GPL</file>, and
8410 <file>/usr/share/common-licenses/LGPL</file> respectively,
8411 rather than quoting them in the copyright file.
8415 You should not use the copyright file as a general <file>README</file>
8416 file. If your package has such a file it should be
8417 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
8418 <file>README.Debian</file> or some other appropriate place.</p>
8422 <heading>Examples</heading>
8425 Any examples (configurations, source files, whatever),
8426 should be installed in a directory
8427 <file>/usr/share/doc/<var>package</var>/examples</file>. These
8428 files should not be referenced by any program: they're there
8429 for the benefit of the system administrator and users as
8430 documentation only. Architecture-specific example files
8431 should be installed in a directory
8432 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
8434 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
8435 latter directory itself may be a symbolic link to the
8440 If the purpose of a package is to provide examples, then the
8441 example files may be installed into
8442 <file>/usr/share/doc/<var>package</var></file>.
8446 <sect id="changelogs">
8447 <heading>Changelog files</heading>
8450 Packages that are not Debian-native must contain a
8451 compressed copy of the <file>debian/changelog</file> file from
8452 the Debian source tree in
8453 <file>/usr/share/doc/<var>package</var></file> with the name
8454 <file>changelog.Debian.gz</file>.
8458 If an upstream changelog is available, it should be accessible as
8459 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
8460 plain text. If the upstream changelog is distributed in
8461 HTML, it should be made available in that form as
8462 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
8463 and a plain text <file>changelog.gz</file> should be generated
8464 from it using, for example, <tt>lynx -dump -nolist</tt>. If
8465 the upstream changelog files do not already conform to this
8466 naming convention, then this may be achieved either by
8467 renaming the files, or by adding a symbolic link, at the
8468 maintainer's discretion.<footnote>
8469 Rationale: People should not have to look in places for
8470 upstream changelogs merely because they are given
8471 different names or are distributed in HTML format.
8476 All of these files should be installed compressed using
8477 <tt>gzip -9</tt>, as they will become large with time even
8478 if they start out small.
8482 If the package has only one changelog which is used both as
8483 the Debian changelog and the upstream one because there is
8484 no separate upstream maintainer then that changelog should
8485 usually be installed as
8486 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
8487 there is a separate upstream maintainer, but no upstream
8488 changelog, then the Debian changelog should still be called
8489 <file>changelog.Debian.gz</file>.
8493 For details about the format and contents of the Debian
8494 changelog file, please see <ref id="dpkgchangelog">.
8499 <appendix id="pkg-scope">
8500 <heading>Introduction and scope of these appendices</heading>
8503 These appendices are taken essentially verbatim from the
8504 now-deprecated Packaging Manual, version 3.2.1.0. They are
8505 the chapters which are likely to be of use to package
8506 maintainers and which have not already been included in the
8507 policy document itself. Most of these sections are very likely
8508 not relevant to policy; they should be treated as
8509 documentation for the packaging system. Please note that these
8510 appendices are included for convenience, and for historical
8511 reasons: they used to be part of policy package, and they have
8512 not yet been incorporated into dpkg documentation. However,
8513 they still have value, and hence they are presented here.
8517 They have not yet been checked to ensure that they are
8518 compatible with the contents of policy, and if there are any
8519 contradictions, the version in the main policy document takes
8520 precedence. The remaining chapters of the old Packaging
8521 Manual have also not been read in detail to ensure that there
8522 are not parts which have been left out. Both of these will be
8527 Certain parts of the Packaging manual were integrated into the
8528 Policy Manual proper, and removed from the appendices. Links
8529 have been placed from the old locations to the new ones.
8533 <prgn>dpkg</prgn> is a suite of programs for creating binary
8534 package files and installing and removing them on Unix
8536 <prgn>dpkg</prgn> is targetted primarily at Debian
8537 GNU/Linux, but may work on or be ported to other
8543 The binary packages are designed for the management of
8544 installed executable programs (usually compiled binaries) and
8545 their associated data, though source code examples and
8546 documentation are provided as part of some packages.</p>
8549 This manual describes the technical aspects of creating Debian
8550 binary packages (<file>.deb</file> files). It documents the
8551 behaviour of the package management programs
8552 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
8553 they interact with packages.</p>
8556 It also documents the interaction between
8557 <prgn>dselect</prgn>'s core and the access method scripts it
8558 uses to actually install the selected packages, and describes
8559 how to create a new access method.</p>
8562 This manual does not go into detail about the options and
8563 usage of the package building and installation tools. It
8564 should therefore be read in conjuction with those programs'
8569 The utility programs which are provided with <prgn>dpkg</prgn>
8570 for managing various system configuration and similar issues,
8571 such as <prgn>update-rc.d</prgn> and
8572 <prgn>install-info</prgn>, are not described in detail here -
8573 please see their manpages.
8577 It is assumed that the reader is reasonably familiar with the
8578 <prgn>dpkg</prgn> System Administrators' manual.
8579 Unfortunately this manual does not yet exist.
8583 The Debian version of the FSF's GNU hello program is provided
8584 as an example for people wishing to create Debian
8585 packages. The Debian <prgn>debmake</prgn> package is
8586 recommended as a very helpful tool in creating and maintaining
8587 Debian packages. However, while the tools and examples are
8588 helpful, they do not replace the need to read and follow the
8589 Policy and Programmer's Manual.</p>
8592 <appendix id="pkg-binarypkg">
8593 <heading>Binary packages (from old Packaging Manual)</heading>
8596 The binary package has two main sections. The first part
8597 consists of various control information files and scripts used
8598 by <prgn>dpkg</prgn> when installing and removing. See <ref
8599 id="pkg-controlarea">.
8603 The second part is an archive containing the files and
8604 directories to be installed.
8608 In the future binary packages may also contain other
8609 components, such as checksums and digital signatures. The
8610 format for the archive is described in full in the
8611 <file>deb(5)</file> manpage.
8615 <sect id="pkg-bincreating"><heading>Creating package files -
8616 <prgn>dpkg-deb</prgn>
8620 All manipulation of binary package files is done by
8621 <prgn>dpkg-deb</prgn>; it's the only program that has
8622 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
8623 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
8624 will spot that the options requested are appropriate to
8625 <prgn>dpkg-deb</prgn> and invoke that instead with the same
8630 In order to create a binary package you must make a
8631 directory tree which contains all the files and directories
8632 you want to have in the filesystem data part of the package.
8633 In Debian-format source packages this directory is usually
8634 <file>debian/tmp</file>, relative to the top of the package's
8639 They should have the locations (relative to the root of the
8640 directory tree you're constructing) ownerships and
8641 permissions which you want them to have on the system when
8646 With current versions of <prgn>dpkg</prgn> the uid/username
8647 and gid/groupname mappings for the users and groups being
8648 used should be the same on the system where the package is
8649 built and the one where it is installed.
8653 You need to add one special directory to the root of the
8654 miniature filesystem tree you're creating:
8655 <prgn>DEBIAN</prgn>. It should contain the control
8656 information files, notably the binary package control file
8657 (see <ref id="pkg-controlfile">).
8661 The <prgn>DEBIAN</prgn> directory will not appear in the
8662 filesystem archive of the package, and so won't be installed
8663 by <prgn>dpkg</prgn> when the package is installed.
8667 When you've prepared the package, you should invoke:
8669 dpkg --build <var>directory</var>
8674 This will build the package in
8675 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
8676 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
8677 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
8682 See the manpage <manref name="dpkg-deb" section="8"> for details of how
8683 to examine the contents of this newly-created file. You may find the
8684 output of following commands enlightening:
8686 dpkg-deb --info <var>filename</var>.deb
8687 dpkg-deb --contents <var>filename</var>.deb
8688 dpkg --contents <var>filename</var>.deb
8690 To view the copyright file for a package you could use this command:
8692 dpkg --fsys-tarfile <var>filename</var>.deb | tar xof usr/share/doc/<var>\*</var>copyright | less
8697 <sect id="pkg-controlarea">
8698 <heading>Package control information files</heading>
8701 The control information portion of a binary package is a
8702 collection of files with names known to <prgn>dpkg</prgn>.
8703 It will treat the contents of these files specially - some
8704 of them contain information used by <prgn>dpkg</prgn> when
8705 installing or removing the package; others are scripts which
8706 the package maintainer wants <prgn>dpkg</prgn> to run.
8710 It is possible to put other files in the package control
8711 area, but this is not generally a good idea (though they
8712 will largely be ignored).
8716 Here is a brief list of the control info files supported by
8717 <prgn>dpkg</prgn> and a summary of what they're used for.
8722 <tag><tt>control</tt>
8725 This is the key description file used by
8726 <prgn>dpkg</prgn>. It specifies the package's name
8727 and version, gives its description for the user,
8728 states its relationships with other packages, and so
8729 forth. See <ref id="sourcecontrolfiles"> and
8730 <ref id="binarycontrolfiles">.
8734 It is usually generated automatically from information
8735 in the source package by the
8736 <prgn>dpkg-gencontrol</prgn> program, and with
8737 assistance from <prgn>dpkg-shlibdeps</prgn>.
8738 See <ref id="pkg-sourcetools">.
8742 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
8747 These are exectuable files (usually scripts) which
8748 <prgn>dpkg</prgn> runs during installation, upgrade
8749 and removal of packages. They allow the package to
8750 deal with matters which are particular to that package
8751 or require more complicated processing than that
8752 provided by <prgn>dpkg</prgn>. Details of when and
8753 how they are called are in <ref id="maintainerscripts">.
8757 It is very important to make these scripts idempotent.
8758 See <ref id="idempotency">.
8762 The maintainer scripts are guaranteed to run with a
8763 controlling terminal and can interact with the user.
8764 See <ref id="controllingterminal">.
8768 <tag><tt>conffiles</tt>
8771 This file contains a list of configuration files which
8772 are to be handled automatically by <prgn>dpkg</prgn>
8773 (see <ref id="pkg-conffiles">). Note that not necessarily
8774 every configuration file should be listed here.
8777 <tag><tt>shlibs</tt>
8780 This file contains a list of the shared libraries
8781 supplied by the package, with dependency details for
8782 each. This is used by <prgn>dpkg-shlibdeps</prgn>
8783 when it determines what dependencies are required in a
8784 package control file. The <tt>shlibs</tt> file format
8785 is described on <ref id="shlibs">.
8790 <sect id="pkg-controlfile">
8791 <heading>The main control information file: <tt>control</tt></heading>
8794 The most important control information file used by
8795 <prgn>dpkg</prgn> when it installs a package is
8796 <tt>control</tt>. It contains all the package's "vital
8801 The binary package control files of packages built from
8802 Debian sources are made by a special tool,
8803 <prgn>dpkg-gencontrol</prgn>, which reads
8804 <file>debian/control</file> and <file>debian/changelog</file> to
8805 find the information it needs. See <ref id="pkg-sourcepkg"> for
8810 The fields in binary package control files are listed in
8811 <ref id="binarycontrolfiles">.
8815 A description of the syntax of control files and the purpose
8816 of the fields is available in <ref id="controlfields">.
8821 <heading>Time Stamps</heading>
8824 See <ref id="timestamps">.
8829 <appendix id="pkg-sourcepkg">
8830 <heading>Source packages (from old Packaging Manual) </heading>
8833 The Debian binary packages in the distribution are generated
8834 from Debian sources, which are in a special format to assist
8835 the easy and automatic building of binaries.
8838 <sect id="pkg-sourcetools">
8839 <heading>Tools for processing source packages</heading>
8842 Various tools are provided for manipulating source packages;
8843 they pack and unpack sources and help build of binary
8844 packages and help manage the distribution of new versions.
8848 They are introduced and typical uses described here; see
8849 <manref name="dpkg-source" section="1"> for full
8850 documentation about their arguments and operation.
8854 For examples of how to construct a Debian source package,
8855 and how to use those utilities that are used by Debian
8856 source packages, please see the <prgn>hello</prgn> example
8862 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
8867 This program is frequently used by hand, and is also
8868 called from package-independent automated building scripts
8869 such as <prgn>dpkg-buildpackage</prgn>.
8873 To unpack a package it is typically invoked with
8875 dpkg-source -x <var>.../path/to/filename</var>.dsc
8880 with the <file><var>filename</var>.tar.gz</file> and
8881 <file><var>filename</var>.diff.gz</file> (if applicable) in
8882 the same directory. It unpacks into
8883 <file><var>package</var>-<var>version</var></file>, and if
8885 <file><var>package</var>-<var>version</var>.orig</file>, in
8886 the current directory.
8890 To create a packed source archive it is typically invoked:
8892 dpkg-source -b <var>package</var>-<var>version</var>
8897 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
8898 <file>.diff.gz</file> (if appropriate) in the current
8899 directory. <prgn>dpkg-source</prgn> does not clean the
8900 source tree first - this must be done separately if it is
8905 See also <ref id="pkg-sourcearchives">.</p>
8911 <prgn>dpkg-buildpackage</prgn> - overall package-building
8916 <prgn>dpkg-buildpackage</prgn> is a script which invokes
8917 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
8918 targets <tt>clean</tt>, <tt>build</tt> and
8919 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
8920 <prgn>pgp</prgn> to build a signed source and binary
8925 It is usually invoked by hand from the top level of the
8926 built or unbuilt source directory. It may be invoked with
8927 no arguments; useful arguments include:
8928 <taglist compact="compact">
8929 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
8932 Do not PGP-sign the <tt>.changes</tt> file or the
8933 source package <tt>.dsc</tt> file, respectively.</p>
8935 <tag><tt>-p<var>pgp-command</var></tt></tag>
8938 Invoke <var>pgp-command</var> instead of finding
8939 <tt>pgp</tt> on the <prgn>PATH</prgn>.
8940 <var>pgp-command</var> must behave just like
8941 <prgn>pgp</prgn>.</p>
8943 <tag><tt>-r<var>root-command</var></tt></tag>
8946 When root privilege is required, invoke the command
8947 <var>root-command</var>. <var>root-command</var>
8948 should invoke its first argument as a command, from
8949 the <prgn>PATH</prgn> if necessary, and pass its
8950 second and subsequent arguments to the command it
8951 calls. If no <var>root-command</var> is supplied
8952 then <var>dpkg-buildpackage</var> will take no
8953 special action to gain root privilege, so that for
8954 most packages it will have to be invoked as root to
8957 <tag><tt>-b</tt>, <tt>-B</tt></tag>
8960 Two types of binary-only build and upload - see
8961 <manref name="dpkg-source" section="1">.
8970 <prgn>dpkg-gencontrol</prgn> - generates binary package
8975 This program is usually called from <file>debian/rules</file>
8976 (see <ref id="pkg-sourcetree">) in the top level of the source
8981 This is usually done just before the files and directories in the
8982 temporary directory tree where the package is being built have their
8983 permissions and ownerships set and the package is constructed using
8984 <prgn>dpkg-deb/</prgn>
8986 This is so that the control file which is produced has
8987 the right permissions
8992 <prgn>dpkg-gencontrol</prgn> must be called after all the
8993 files which are to go into the package have been placed in
8994 the temporary build directory, so that its calculation of
8995 the installed size of a package is correct.
8999 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9000 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9001 variable substitutions created by
9002 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9007 For a package which generates only one binary package, and
9008 which builds it in <file>debian/tmp</file> relative to the top
9009 of the source package, it is usually sufficient to call
9010 <prgn>dpkg-gencontrol</prgn>.
9014 Sources which build several binaries will typically need
9017 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9018 </example> The <tt>-P</tt> tells
9019 <prgn>dpkg-gencontrol</prgn> that the package is being
9020 built in a non-default directory, and the <tt>-p</tt>
9021 tells it which package's control file should be generated.
9025 <prgn>dpkg-gencontrol</prgn> also adds information to the
9026 list of files in <file>debian/files</file>, for the benefit of
9027 (for example) a future invocation of
9028 <prgn>dpkg-genchanges</prgn>.</p>
9033 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9038 This program is usually called from <file>debian/rules</file>
9039 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9040 id="pkg-sourcetree">), in the top level of the source tree.
9044 Its arguments are executables.
9047 In a forthcoming dpkg version,
9048 <prgn>dpkg-shlibdeps</prgn> would be required to be
9049 called on shared libraries as well.
9052 They may be specified either in the locations in the
9053 source tree where they are created or in the locations
9054 in the temporary build tree where they are installed
9055 prior to binary package creation.
9057 </footnote> for which shared library dependencies should
9058 be included in the binary package's control file.
9062 If some of the found shared libraries should only
9063 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9064 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9065 by using the <tt>-d<var>dependency-field</var></tt> option
9066 before those executable(s). (Each <tt>-d</tt> option
9067 takes effect until the next <tt>-d</tt>.)
9071 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9072 output control file to be modified. Instead by default it
9073 adds to the <file>debian/substvars</file> file variable
9074 settings like <tt>shlibs:Depends</tt>. These variable
9075 settings must be referenced in dependency fields in the
9076 appropriate per-binary-package sections of the source
9081 For example, the <prgn>procps</prgn> package generates two
9082 kinds of binaries, simple C binaries like <prgn>ps</prgn>
9083 which require a predependency and full-screen ncurses
9084 binaries like <prgn>top</prgn> which require only a
9085 recommendation. It can say in its <file>debian/rules</file>:
9087 dpkg-shlibdeps -dPre-Depends ps -dRecommends top
9089 and then in its main control file <file>debian/control</file>:
9093 Pre-Depends: ${shlibs:Pre-Depends}
9094 Recommends: ${shlibs:Recommends}
9100 Sources which produce several binary packages with
9101 different shared library dependency requirements can use
9102 the <tt>-p<var>varnameprefix</var></tt> option to override
9103 the default <tt>shlibs:</tt> prefix (one invocation of
9104 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9105 They can thus produce several sets of dependency
9106 variables, each of the form
9107 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9108 which can be referred to in the appropriate parts of the
9109 binary package control files.
9116 <prgn>dpkg-distaddfile</prgn> - adds a file to
9117 <file>debian/files</file>
9121 Some packages' uploads need to include files other than
9122 the source and binary package files.
9126 <prgn>dpkg-distaddfile</prgn> adds a file to the
9127 <file>debian/files</file> file so that it will be included in
9128 the <file>.changes</file> file when
9129 <prgn>dpkg-genchanges</prgn> is run.
9133 It is usually invoked from the <tt>binary</tt> target of
9134 <file>debian/rules</file>:
9136 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9138 The <var>filename</var> is relative to the directory where
9139 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9140 is usually the directory above the top level of the source
9141 tree. The <file>debian/rules</file> target should put the
9142 file there just before or just after calling
9143 <prgn>dpkg-distaddfile</prgn>.
9147 The <var>section</var> and <var>priority</var> are passed
9148 unchanged into the resulting <file>.changes</file> file.
9153 <sect1><heading><prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file> upload
9158 This program is usually called by package-independent
9159 automatic building scripts such as
9160 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9165 It is usually called in the top level of a built source
9166 tree, and when invoked with no arguments will print out a
9167 straightforward <file>.changes</file> file based on the
9168 information in the source package's changelog and control
9169 file and the binary and source packages which should have
9175 <sect1><heading><prgn>dpkg-parsechangelog</prgn> - produces parsed representation of
9180 This program is used internally by
9181 <prgn>dpkg-source</prgn> et al. It may also occasionally
9182 be useful in <file>debian/rules</file> and elsewhere. It
9183 parses a changelog, <file>debian/changelog</file> by default,
9184 and prints a control-file format representation of the
9185 information in it to standard output.
9189 <sect1 id="pkg-dpkgarch"><heading><prgn>dpkg-architecture</prgn> -
9190 information about the build and host system
9194 This program can be used manually, but is also invoked by
9195 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9196 to set environment or make variables which specify the build and
9197 host architecture for the package building process.
9202 <sect id="pkg-sourcetree">
9203 <heading>The Debianised source tree</heading>
9206 The source archive scheme described later is intended to
9207 allow a Debianised source tree with some associated control
9208 information to be reproduced and transported easily. The
9209 Debianised source tree is a version of the original program
9210 with certain files added for the benefit of the
9211 Debianisation process, and with any other changes required
9212 made to the rest of the source code and installation
9217 The extra files created for Debian are in the subdirectory
9218 <file>debian</file> of the top level of the Debianised source
9219 tree. They are described below.
9222 <sect1 id="pkg-debianrules">
9223 <heading><file>debian/rules</file> - the main building script</heading>
9226 See <ref id="debianrules">.
9231 <sect1 id="pkg-dpkgchangelog">
9232 <heading><file>debian/changelog</file></heading>
9235 See <ref id="dpkgchangelog">.
9239 It is recommended that the entire changelog be encoded in the
9240 <url id="http://www.cis.ohio-state.edu/cgi-bin/rfc/rfc2279.html" name="UTF-8">
9242 <url id="http://www.unicode.org/"
9243 name="Unicode">.<footnote>
9245 Support for Unicode, and specifically UTF-8, is
9246 steadily increasing among popular applications in
9247 Debian. For example, in unstable, GNOME 2 has
9248 excellent support (almost level 2) in almost all its
9249 applications; the big remaining one is gnome-terminal,
9250 of which one requires development versions in order to
9251 support UTF-8 (available in Debian experimental now if
9252 you want to play). I think that by the time sarge is
9253 released, UTF-8 support will start to hit critical
9256 I think it is fairly obvious that we need to
9257 eventually transition to UTF-8 for our package
9258 infrastructure; it is really the only sane charset in
9259 an international environment. Now, we can't switch to
9260 using UTF-8 for package control fields and the like
9261 until dpkg has better support, but one thing we can
9262 start doing today is requesting that Debian changelogs
9263 are UTF-8 encoded. At some point in time, we can start
9264 requiring them to do so.
9267 Checking for non-UTF8 characters in a changelog is
9268 trivial. Dump the file through
9269 <example>iconv -f utf-8 -t ucs-4</example>
9270 discard the output, and check the return
9271 value. If there are any characters in the stream
9272 which are invalid UTF-8 sequences, iconv will exit
9273 with an error code; and this will be the case for the
9274 vast majority of other character sets.
9279 <sect2><heading>Defining alternative changelog formats
9283 It is possible to use a different format to the standard
9284 one, by providing a parser for the format you wish to
9289 In order to have <tt>dpkg-parsechangelog</tt> run your
9290 parser, you must include a line within the last 40 lines
9291 of your file matching the Perl regular expression:
9292 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9293 parentheses should be the name of the format. For
9294 example, you might say:
9296 @@@ changelog-format: joebloggs @@@
9298 Changelog format names are non-empty strings of alphanumerics.
9302 If such a line exists then <tt>dpkg-parsechangelog</tt>
9303 will look for the parser as
9304 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9306 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9307 it is an error for it not to find it, or for it not to
9308 be an executable program. The default changelog format
9309 is <tt>dpkg</tt>, and a parser for it is provided with
9310 the <tt>dpkg</tt> package.
9314 The parser will be invoked with the changelog open on
9315 standard input at the start of the file. It should read
9316 the file (it may seek if it wishes) to determine the
9317 information required and return the parsed information
9318 to standard output in the form of a series of control
9319 fields in the standard format. By default it should
9320 return information about only the most recent version in
9321 the changelog; it should accept a
9322 <tt>-v<var>version</var></tt> option to return changes
9323 information from all versions present <em>strictly
9324 after</em> <var>version</var>, and it should then be an
9325 error for <var>version</var> not to be present in the
9331 <list compact="compact">
9332 <item><qref id="f-Source"><tt>Source</tt></qref></item>
9333 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
9334 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
9335 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
9336 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
9337 <item><qref id="f-Date"><tt>Date</tt></qref></item>
9338 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
9343 If several versions are being returned (due to the use
9344 of <tt>-v</tt>), the urgency value should be of the
9345 highest urgency code listed at the start of any of the
9346 versions requested followed by the concatenated
9347 (space-separated) comments from all the versions
9348 requested; the maintainer, version, distribution and
9349 date should always be from the most recent version.
9353 For the format of the <tt>Changes</tt> field see
9354 <ref id="f-Changes">.
9358 If the changelog format which is being parsed always or
9359 almost always leaves a blank line between individual
9360 change notes these blank lines should be stripped out,
9361 so as to make the resulting output compact.
9365 If the changelog format does not contain date or package
9366 name information this information should be omitted from
9367 the output. The parser should not attempt to synthesise
9368 it or find it from other sources.
9372 If the changelog does not have the expected format the
9373 parser should exit with a nonzero exit status, rather
9374 than trying to muddle through and possibly generating
9379 A changelog parser may not interact with the user at
9385 <sect1 id="pkg-srcsubstvars">
9386 <heading><file>debian/substvars</file> and variable substitutions</heading>
9389 See <ref id="substvars">.
9395 <heading><file>debian/files</file></heading>
9398 See <ref id="debianfiles">.
9402 <sect1><heading><file>debian/tmp</file>
9406 This is the canonical temporary location for the
9407 construction of binary packages by the <tt>binary</tt>
9408 target. The directory <file>tmp</file> serves as the root of
9409 the filesystem tree as it is being constructed (for
9410 example, by using the package's upstream makefiles install
9411 targets and redirecting the output there), and it also
9412 contains the <tt>DEBIAN</tt> subdirectory. See <ref
9413 id="pkg-bincreating">.
9417 If several binary packages are generated from the same
9418 source tree it is usual to use several
9419 <file>debian/tmp<var>something</var></file> directories, for
9420 example <file>tmp-a</file> or <file>tmp-doc</file>.
9424 Whatever <file>tmp</file> directories are created and used by
9425 <tt>binary</tt> must of course be removed by the
9426 <tt>clean</tt> target.</p></sect1>
9430 <sect id="pkg-sourcearchives"><heading>Source packages as archives
9434 As it exists on the FTP site, a Debian source package
9435 consists of three related files. You must have the right
9436 versions of all three to be able to use them.
9441 <tag>Debian source control file - <tt>.dsc</tt></tag>
9443 This file is a control file used by <prgn>dpkg-source</prgn>
9444 to extract a source package.
9445 See <ref id="debiansourcecontrolfiles">.
9449 Original source archive -
9451 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
9458 This is a compressed (with <tt>gzip -9</tt>)
9459 <prgn>tar</prgn> file containing the source code from
9460 the upstream authors of the program. The tarfile
9461 unpacks into a directory
9462 <file><var>package</var>-<var>upstream-version</var>.orig</file>,
9463 and does not contain files anywhere other than in
9464 there or in its subdirectories.</p>
9468 Debianisation diff -
9470 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
9476 This is a unified context diff (<tt>diff -u</tt>)
9477 giving the changes which are required to turn the
9478 original source into the Debian source. These changes
9479 may only include editing and creating plain files.
9480 The permissions of files, the targets of symbolic
9481 links and the characteristics of special files or
9482 pipes may not be changed and no files may be removed
9487 All the directories in the diff must exist, except the
9488 <file>debian</file> subdirectory of the top of the source
9489 tree, which will be created by
9490 <prgn>dpkg-source</prgn> if necessary when unpacking.
9494 The <prgn>dpkg-source</prgn> program will
9495 automatically make the <file>debian/rules</file> file
9496 executable (see below).</p></item>
9501 If there is no original source code - for example, if the
9502 package is specially prepared for Debian or the Debian
9503 maintainer is the same as the upstream maintainer - the
9504 format is slightly different: then there is no diff, and the
9506 <file><var>package</var>_<var>version</var>.tar.gz</file> and
9507 contains a directory
9508 <file><var>package</var>-<var>version</var></file>.
9513 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
9516 <tt>dpkg-source -x</tt> is the recommended way to unpack a
9517 Debian source package. However, if it is not available it
9518 is possible to unpack a Debian source archive as follows:
9519 <enumlist compact="compact">
9522 Untar the tarfile, which will create a <file>.orig</file>
9526 <p>Rename the <file>.orig</file> directory to
9527 <file><var>package</var>-<var>version</var></file>.</p>
9531 Create the subdirectory <file>debian</file> at the top of
9532 the source tree.</p>
9534 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
9536 <item><p>Untar the tarfile again if you want a copy of the original
9537 source code alongside the Debianised version.</p>
9542 It is not possible to generate a valid Debian source archive
9543 without using <prgn>dpkg-source</prgn>. In particular,
9544 attempting to use <prgn>diff</prgn> directly to generate the
9545 <file>.diff.gz</file> file will not work.
9549 <heading>Restrictions on objects in source packages</heading>
9552 The source package may not contain any hard links
9554 This is not currently detected when building source
9555 packages, but only when extracting
9559 Hard links may be permitted at some point in the
9560 future, but would require a fair amount of
9562 </footnote>, device special files, sockets or setuid or
9565 Setgid directories are allowed.
9570 The source packaging tools manage the changes between the
9571 original and Debianised source using <prgn>diff</prgn> and
9572 <prgn>patch</prgn>. Turning the original source tree as
9573 included in the <file>.orig.tar.gz</file> into the debianised
9574 source must not involve any changes which cannot be
9575 handled by these tools. Problematic changes which cause
9576 <prgn>dpkg-source</prgn> to halt with an error when
9577 building the source package are:
9578 <list compact="compact">
9579 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
9581 <item><p>Changing the targets of symbolic links.</p>
9583 <item><p>Creating directories, other than <file>debian</file>.</p>
9585 <item><p>Changes to the contents of binary files.</p></item>
9586 </list> Changes which cause <prgn>dpkg-source</prgn> to
9587 print a warning but continue anyway are:
9588 <list compact="compact">
9591 Removing files, directories or symlinks.
9593 Renaming a file is not treated specially - it is
9594 seen as the removal of the old file (which
9595 generates a warning, but is otherwise ignored),
9596 and the creation of the new one.
9602 Changed text files which are missing the usual final
9603 newline (either in the original or the modified
9608 Changes which are not represented, but which are not detected by
9609 <prgn>dpkg-source</prgn>, are:
9610 <list compact="compact">
9611 <item><p>Changing the permissions of files (other than
9612 <file>debian/rules</file>) and directories.</p></item>
9617 The <file>debian</file> directory and <file>debian/rules</file>
9618 are handled specially by <prgn>dpkg-source</prgn> - before
9619 applying the changes it will create the <file>debian</file>
9620 directory, and afterwards it will make
9621 <file>debian/rules</file> world-exectuable.
9627 <appendix id="pkg-controlfields">
9628 <heading>Control files and their fields (from old Packaging Manual)</heading>
9631 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
9632 data in a common format, known as control files. Binary and
9633 source packages have control data as do the <file>.changes</file>
9634 files which control the installation of uploaded files, and
9635 <prgn>dpkg</prgn>'s internal databases are in a similar
9640 <heading>Syntax of control files</heading>
9643 See <ref id="controlsyntax">.
9647 It is important to note that there are several fields which
9648 are optional as far as <prgn>dpkg</prgn> and the related
9649 tools are concerned, but which must appear in every Debian
9650 package, or whose omission may cause problems.
9655 <heading>List of fields</heading>
9658 See <ref id="controlfieldslist">.
9662 This section now contains only the fields that didn't belong
9663 to the Policy manual.
9666 <sect1 id="pkg-f-Filename">
9667 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
9670 These fields in <tt>Packages</tt> files give the
9671 filename(s) of (the parts of) a package in the
9672 distribution directories, relative to the root of the
9673 Debian hierarchy. If the package has been split into
9674 several parts the parts are all listed in order, separated
9679 <sect1 id="pkg-f-Size">
9680 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
9683 These fields in <file>Packages</file> files give the size (in
9684 bytes, expressed in decimal) and MD5 checksum of the
9685 file(s) which make(s) up a binary package in the
9686 distribution. If the package is split into several parts
9687 the values for the parts are listed in order, separated by
9692 <sect1 id="pkg-f-Status">
9693 <heading><tt>Status</tt></heading>
9696 This field in <prgn>dpkg</prgn>'s status file records
9697 whether the user wants a package installed, removed or
9698 left alone, whether it is broken (requiring
9699 reinstallation) or not and what its current state on the
9700 system is. Each of these pieces of information is a
9705 <sect1 id="pkg-f-Config-Version">
9706 <heading><tt>Config-Version</tt></heading>
9709 If a package is not installed or not configured, this
9710 field in <prgn>dpkg</prgn>'s status file records the last
9711 version of the package which was successfully
9716 <sect1 id="pkg-f-Conffiles">
9717 <heading><tt>Conffiles</tt></heading>
9720 This field in <prgn>dpkg</prgn>'s status file contains
9721 information about the automatically-managed configuration
9722 files held by a package. This field should <em>not</em>
9723 appear anywhere in a package!
9728 <heading>Obsolete fields</heading>
9731 These are still recognised by <prgn>dpkg</prgn> but should
9732 not appear anywhere any more.
9734 <taglist compact="compact">
9736 <tag><tt>Revision</tt></tag>
9737 <tag><tt>Package-Revision</tt></tag>
9738 <tag><tt>Package_Revision</tt></tag>
9740 The Debian revision part of the package version was
9741 at one point in a separate control file field. This
9742 field went through several names.
9745 <tag><tt>Recommended</tt></tag>
9746 <item>Old name for <tt>Recommends</tt>.</item>
9748 <tag><tt>Optional</tt></tag>
9749 <item>Old name for <tt>Suggests</tt>.</item>
9751 <tag><tt>Class</tt></tag>
9752 <item>Old name for <tt>Priority</tt>.</item>
9761 <appendix id="pkg-conffiles">
9762 <heading>Configuration file handling (from old Packaging Manual)</heading>
9765 <prgn>dpkg</prgn> can do a certain amount of automatic
9766 handling of package configuration files.
9770 Whether this mechanism is appropriate depends on a number of
9771 factors, but basically there are two approaches to any
9772 particular configuration file.
9776 The easy method is to ship a best-effort configuration in the
9777 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
9778 handle updates. If the user is unlikely to want to edit the
9779 file, but you need them to be able to without losing their
9780 changes, and a new package with a changed version of the file
9781 is only released infrequently, this is a good approach.
9785 The hard method is to build the configuration file from
9786 scratch in the <prgn>postinst</prgn> script, and to take the
9787 responsibility for fixing any mistakes made in earlier
9788 versions of the package automatically. This will be
9789 appropriate if the file is likely to need to be different on
9793 <sect><heading>Automatic handling of configuration files by
9798 A package may contain a control area file called
9799 <tt>conffiles</tt>. This file should be a list of filenames
9800 of configuration files needing automatic handling, separated
9801 by newlines. The filenames should be absolute pathnames,
9802 and the files referred to should actually exist in the
9807 When a package is upgraded <prgn>dpkg</prgn> will process
9808 the configuration files during the configuration stage,
9809 shortly before it runs the package's <prgn>postinst</prgn>
9814 For each file it checks to see whether the version of the
9815 file included in the package is the same as the one that was
9816 included in the last version of the package (the one that is
9817 being upgraded from); it also compares the version currently
9818 installed on the system with the one shipped with the last
9823 If neither the user nor the package maintainer has changed
9824 the file, it is left alone. If one or the other has changed
9825 their version, then the changed version is preferred - i.e.,
9826 if the user edits their file, but the package maintainer
9827 doesn't ship a different version, the user's changes will
9828 stay, silently, but if the maintainer ships a new version
9829 and the user hasn't edited it the new version will be
9830 installed (with an informative message). If both have
9831 changed their version the user is prompted about the problem
9832 and must resolve the differences themselves.
9836 The comparisons are done by calculating the MD5 message
9837 digests of the files, and storing the MD5 of the file as it
9838 was included in the most recent version of the package.
9842 When a package is installed for the first time
9843 <prgn>dpkg</prgn> will install the file that comes with it,
9844 unless that would mean overwriting a file already on the
9849 However, note that <prgn>dpkg</prgn> will <em>not</em>
9850 replace a conffile that was removed by the user (or by a
9851 script). This is necessary because with some programs a
9852 missing file produces an effect hard or impossible to
9853 achieve in another way, so that a missing file needs to be
9854 kept that way if the user did it.
9858 Note that a package should <em>not</em> modify a
9859 <prgn>dpkg</prgn>-handled conffile in its maintainer
9860 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
9861 the user confusing and possibly dangerous options for
9862 conffile update when the package is upgraded.</p>
9865 <sect><heading>Fully-featured maintainer script configuration
9870 For files which contain site-specific information such as
9871 the hostname and networking details and so forth, it is
9872 better to create the file in the package's
9873 <prgn>postinst</prgn> script.
9877 This will typically involve examining the state of the rest
9878 of the system to determine values and other information, and
9879 may involve prompting the user for some information which
9880 can't be obtained some other way.
9884 When using this method there are a couple of important
9885 issues which should be considered:
9889 If you discover a bug in the program which generates the
9890 configuration file, or if the format of the file changes
9891 from one version to the next, you will have to arrange for
9892 the postinst script to do something sensible - usually this
9893 will mean editing the installed configuration file to remove
9894 the problem or change the syntax. You will have to do this
9895 very carefully, since the user may have changed the file,
9896 perhaps to fix the very problem that your script is trying
9897 to deal with - you will have to detect these situations and
9898 deal with them correctly.
9902 If you do go down this route it's probably a good idea to
9903 make the program that generates the configuration file(s) a
9904 separate program in <file>/usr/sbin</file>, by convention called
9905 <file><var>package</var>config</file> and then run that if
9906 appropriate from the post-installation script. The
9907 <tt><var>package</var>config</tt> program should not
9908 unquestioningly overwrite an existing configuration - if its
9909 mode of operation is geared towards setting up a package for
9910 the first time (rather than any arbitrary reconfiguration
9911 later) you should have it check whether the configuration
9912 already exists, and require a <tt>--force</tt> flag to
9913 overwrite it.</p></sect>
9916 <appendix id="pkg-alternatives"><heading>Alternative versions of
9917 an interface - <prgn>update-alternatives</prgn> (from old
9922 When several packages all provide different versions of the
9923 same program or file it is useful to have the system select a
9924 default, but to allow the system administrator to change it
9925 and have their decisions respected.
9929 For example, there are several versions of the <prgn>vi</prgn>
9930 editor, and there is no reason to prevent all of them from
9931 being installed at once, each under their own name
9932 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
9933 Nevertheless it is desirable to have the name <tt>vi</tt>
9934 refer to something, at least by default.
9938 If all the packages involved cooperate, this can be done with
9939 <prgn>update-alternatives</prgn>.
9943 Each package provides its own version under its own name, and
9944 calls <prgn>update-alternatives</prgn> in its postinst to
9945 register its version (and again in its prerm to deregister
9950 See the manpage <manref name="update-alternatives"
9951 section="8"> for details.
9955 If <prgn>update-alternatives</prgn> does not seem appropriate
9956 you may wish to consider using diversions instead.</p>
9959 <appendix id="pkg-diversions"><heading>Diversions - overriding a
9960 package's version of a file (from old Packaging Manual)
9964 It is possible to have <prgn>dpkg</prgn> not overwrite a file
9965 when it reinstalls the package it belongs to, and to have it
9966 put the file from the package somewhere else instead.
9970 This can be used locally to override a package's version of a
9971 file, or by one package to override another's version (or
9972 provide a wrapper for it).
9976 Before deciding to use a diversion, read <ref
9977 id="pkg-alternatives"> to see if you really want a diversion
9978 rather than several alternative versions of a program.
9982 There is a diversion list, which is read by <prgn>dpkg</prgn>,
9983 and updated by a special program <prgn>dpkg-divert</prgn>.
9984 Please see <manref name="dpkg-divert" section="8"> for full
9985 details of its operation.
9989 When a package wishes to divert a file from another, it should
9990 call <prgn>dpkg-divert</prgn> in its preinst to add the
9991 diversion and rename the existing file. For example,
9992 supposing that a <prgn>smailwrapper</prgn> package wishes to
9993 install a wrapper around <file>/usr/sbin/smail</file>:
9995 if [ install = "$1" ]; then
9996 dpkg-divert --package smailwrapper --add --rename \
9997 --divert /usr/sbin/smail.real /usr/sbin/smail
9999 </example> Testing <tt>$1</tt> is necessary so that the script
10000 doesn't try to add the diversion again when
10001 <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
10002 smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
10003 copy of <file>/usr/sbin/smail</file> can bypass the diversion and
10004 get installed as the true version.
10008 The postrm has to do the reverse:
10010 if [ remove = "$1" ]; then
10011 dpkg-divert --package smailwrapper --remove --rename \
10012 --divert /usr/sbin/smail.real /usr/sbin/smail
10018 Do not attempt to divert a file which is vitally important for
10019 the system's operation - when using <prgn>dpkg-divert</prgn>
10020 there is a time, after it has been diverted but before
10021 <prgn>dpkg</prgn> has installed the new version, when the file
10022 does not exist.</p>
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