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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 should be done by communicating
1238 through a program, such as <prgn>debconf</prgn>, which
1239 conforms to the Debian Configuration management
1240 specification, version 2 or higher. Prompting the user by
1241 other means, such as by hand<footnote>
1242 From the Jargon file: by hand 2. By extension,
1243 writing code which does something in an explicit or
1244 low-level way for which a presupplied library
1245 (<em>debconf, in this instance</em>) routine ought
1246 to have been available.
1247 </footnote>, is now deprecated.
1251 The Debian Configuration management specification is included
1252 in the <file>debconf_specification</file> files in the
1253 <package>debian-policy</package> package.
1254 It is also available from the Debian web mirrors at
1255 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1256 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>
1257 and from the Debian archive mirrors at
1258 <tt><url name="/doc/package-developer/debconf_specification.txt.gz"
1259 id="http://ftp.debian.org/debian/doc/package-developer/debconf_specification.txt.gz"></tt>.
1263 Packages which use the Debian Configuration management
1264 specification may contain an additional
1265 <prgn>config</prgn> script and a <tt>templates</tt>
1266 file in their control archive<footnote>
1267 The control.tar.gz inside the .deb.
1268 See <manref name="deb" section="5">.
1270 The <prgn>config</prgn> script might be run before the
1271 <prgn>preinst</prgn> script, and before the package is unpacked
1272 or any of its dependencies or pre-dependancies are satisfied.
1273 Therefore it must work using only the tools present in
1274 <em>essential</em> packages.<footnote>
1275 <package>Debconf</package> or another tool that
1276 implements the Debian Configuration management
1277 specification will also be installed, and any
1278 versioned dependencies on it will be satisfied
1279 before preconfiguration begins.
1284 Packages should try to minimize the amount of prompting
1285 they need to do, and they should ensure that the user
1286 will only ever be asked each question once. This means
1287 that packages should try to use appropriate shared
1288 configuration files (such as <file>/etc/papersize</file> and
1289 <file>/etc/news/server</file>), and shared
1290 <package>debconf</package> variables rather than each
1291 prompting for their own list of required pieces of
1296 It also means that an upgrade should not ask the same
1297 questions again, unless the user has used
1298 <tt>dpkg --purge</tt> to remove the package's configuration.
1299 The answers to configuration questions should be stored in an
1300 appropriate place in <file>/etc</file> so that the user can
1301 modify them, and how this has been done should be
1306 If a package has a vitally important piece of
1307 information to pass to the user (such as "don't run me
1308 as I am, you must edit the following configuration files
1309 first or you risk your system emitting badly-formatted
1310 messages"), it should display this in the
1311 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1312 prompt the user to hit return to acknowledge the
1313 message. Copyright messages do not count as vitally
1314 important (they belong in
1315 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1316 neither do instructions on how to use a program (these
1317 should be in on-line documentation, where all the users
1322 Any necessary prompting should almost always be confined
1323 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1324 script. If it is done in the <prgn>postinst</prgn>, it
1325 should be protected with a conditional so that
1326 unnecessary prompting doesn't happen if a package's
1327 installation fails and the <prgn>postinst</prgn> is
1328 called with <tt>abort-upgrade</tt>,
1329 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1339 <heading>Source packages</heading>
1341 <sect id="standardsversion">
1342 <heading>Standards conformance</heading>
1345 Source packages should specify the most recent version number
1346 of this policy document with which your package complied
1347 when it was last updated.
1351 This information may be used to file bug reports
1352 automatically if your package becomes too much out of date.
1356 The version is specified in the <tt>Standards-Version</tt>
1358 The format of the <tt>Standards-Version</tt> field is
1359 described in <ref id="f-Standards-Version">.
1363 You should regularly, and especially if your package has
1364 become out of date, check for the newest Policy Manual
1365 available and update your package, if necessary. When your
1366 package complies with the new standards you should update the
1367 <tt>Standards-Version</tt> source package field and
1368 release it.<footnote>
1369 See the file <file>upgrading-checklist</file> for
1370 information about policy which has changed between
1371 different versions of this document.
1377 <sect id="pkg-relations">
1378 <heading>Package relationships</heading>
1381 Source packages should specify which binary packages they
1382 require to be installed or not to be installed in order to
1383 build correctly. For example, if building a package
1384 requires a certain compiler, then the compiler should be
1385 specified as a build-time dependency.
1389 It is not necessary to explicitly specify build-time
1390 relationships on a minimal set of packages that are always
1391 needed to compile, link and put in a Debian package a
1392 standard "Hello World!" program written in C or C++. The
1393 required packages are called <em>build-essential</em>, and
1394 an informational list can be found in
1395 <file>/usr/share/doc/build-essential/list</file> (which is
1396 contained in the <tt>build-essential</tt>
1399 <list compact="compact">
1401 This allows maintaining the list separately
1402 from the policy documents (the list does not
1403 need the kind of control that the policy
1407 Having a separate package allows one to install
1408 the build-essential packages on a machine, as
1409 well as allowing other packages such as tasks to
1410 require installation of the build-essential
1411 packages using the depends relation.
1414 The separate package allows bug reports against
1415 the list to be categorized separately from
1416 the policy management process in the BTS.
1423 When specifying the set of build-time dependencies, one
1424 should list only those packages explicitly required by the
1425 build. It is not necessary to list packages which are
1426 required merely because some other package in the list of
1427 build-time dependencies depends on them.<footnote>
1428 The reason for this is that dependencies change, and
1429 you should list all those packages, and <em>only</em>
1430 those packages that <em>you</em> need directly. What
1431 others need is their business. For example, if you
1432 only link against <file>libimlib</file>, you will need to
1433 build-depend on <package>libimlib2-dev</package> but
1434 not against any <tt>libjpeg*</tt> packages, even
1435 though <tt>libimlib2-dev</tt> currently depends on
1436 them: installation of <package>libimlib2-dev</package>
1437 will automatically ensure that all of its run-time
1438 dependencies are satisfied.
1443 If build-time dependencies are specified, it must be
1444 possible to build the package and produce working binaries
1445 on a system with only essential and build-essential
1446 packages installed and also those required to satisfy the
1447 build-time relationships (including any implied
1448 relationships). In particular, this means that version
1449 clauses should be used rigorously in build-time
1450 relationships so that one cannot produce bad or
1451 inconsistently configured packages when the relationships
1452 are properly satisfied.
1456 <ref id="relationships"> explains the technical details.
1461 <heading>Changes to the upstream sources</heading>
1464 If changes to the source code are made that are not
1465 specific to the needs of the Debian system, they should be
1466 sent to the upstream authors in whatever form they prefer
1467 so as to be included in the upstream version of the
1472 If you need to configure the package differently for
1473 Debian or for Linux, and the upstream source doesn't
1474 provide a way to do so, you should add such configuration
1475 facilities (for example, a new <prgn>autoconf</prgn> test
1476 or <tt>#define</tt>) and send the patch to the upstream
1477 authors, with the default set to the way they originally
1478 had it. You can then easily override the default in your
1479 <file>debian/rules</file> or wherever is appropriate.
1483 You should make sure that the <prgn>configure</prgn> utility
1484 detects the correct architecture specification string
1485 (refer to <ref id="arch-spec"> for details).
1489 If you need to edit a <prgn>Makefile</prgn> where
1490 GNU-style <prgn>configure</prgn> scripts are used, you
1491 should edit the <file>.in</file> files rather than editing the
1492 <prgn>Makefile</prgn> directly. This allows the user to
1493 reconfigure the package if necessary. You should
1494 <em>not</em> configure the package and edit the generated
1495 <prgn>Makefile</prgn>! This makes it impossible for
1496 someone else to later reconfigure the package.
1501 <sect id="dpkgchangelog">
1502 <heading>Debian changelog: <file>debian/changelog</file></heading>
1505 Changes in the Debian version of the package should be
1506 briefly explained in the Debian changelog file
1507 <file>debian/changelog</file>. This includes modifications
1508 made in the Debian package compared to the upstream one
1509 as well as other changes and updates to the package.
1511 Although there is nothing stopping an author who is also
1512 the Debian maintainer from using this changelog for all
1513 their changes, it will have to be renamed if the Debian
1514 and upstream maintainers become different people. In such
1515 a case, however, it might be better to maintain the package
1516 as a non-native package.
1521 Mistakes in changelogs are usually best rectified by making
1522 a new changelog entry rather than "rewriting history" by
1523 editing old changelog entries.
1527 The format of the <file>debian/changelog</file> allows the
1528 package building tools to discover which version of the package
1529 is being built and find out other release-specific information.
1533 That format is a series of entries like this:
1535 <example compact="compact">
1536 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1538 [optional blank line(s), stripped]
1540 * <var>change details</var>
1541 <var>more change details</var>
1543 [blank line(s), included in output of dpkg-parsechangelog]
1545 * <var>even more change details</var>
1547 [optional blank line(s), stripped]
1549 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1554 <var>package</var> and <var>version</var> are the source
1555 package name and version number.
1559 <var>distribution(s)</var> lists the distributions where
1560 this version should be installed when it is uploaded - it
1561 is copied to the <tt>Distribution</tt> field in the
1562 <file>.changes</file> file. See <ref id="f-Distribution">.
1566 <var>urgency</var> is the value for the <tt>Urgency</tt>
1567 field in the <file>.changes</file> file for the upload
1568 (see <ref id="f-Urgency">). It is not possible to specify
1569 an urgency containing commas; commas are used to separate
1570 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1571 <prgn>dpkg</prgn> changelog format (though there is
1572 currently only one useful <var>keyword</var>,
1573 <tt>urgency</tt>).<footnote>
1574 Recognised urgency values are <tt>low</tt>,
1575 <tt>medium</tt>, <tt>high</tt> and <tt>emergency</tt>.
1576 They have an effect on how quickly a package will be
1577 considered for inclusion into the <tt>testing</tt>
1578 distribution, and give an indication of the importance
1579 of any fixes included in this upload.
1584 The change details may in fact be any series of lines
1585 starting with at least two spaces, but conventionally each
1586 change starts with an asterisk and a separating space and
1587 continuation lines are indented so as to bring them in
1588 line with the start of the text above. Blank lines may be
1589 used here to separate groups of changes, if desired.
1593 If this upload resolves bugs recorded in the Bug Tracking
1594 System (BTS), they may be automatically closed on the
1595 inclusion of this package into the Debian archive by
1596 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1597 in the change details.<footnote>
1598 To be precise, the string should match the following
1599 Perl regular expression:
1601 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1603 Then all of the bug numbers listed will be closed by the
1604 archive maintenance script (<prgn>katie</prgn>), or in
1605 the case of an NMU, marked as fixed.
1607 This information is conveyed via the <tt>Closes</tt> field
1608 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1612 The maintainer name and email address used in the changelog
1613 should be the details of the person uploading <em>this</em>
1614 version. They are <em>not</em> necessarily those of the
1615 usual package maintainer. The information here will be
1616 copied to the <tt>Changed-By</tt> field in the
1617 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1618 and then later used to send an acknowledgement when the
1619 upload has been installed.
1623 The <var>date</var> should be in RFC822 format<footnote>
1624 This is generated by the <prgn>822-date</prgn>
1626 </footnote>; it should include the time zone specified
1627 numerically, with the time zone name or abbreviation
1628 optionally present as a comment in parentheses.
1632 The first "title" line with the package name should start
1633 at the left hand margin; the "trailer" line with the
1634 maintainer and date details should be preceded by exactly
1635 one space. The maintainer details and the date must be
1636 separated by exactly two spaces.
1640 For more information on placement of the changelog files
1641 within binary packages, please see <ref id="changelogs">.
1644 <sect1><heading>Alternative changelog formats</heading>
1647 In non-experimental packages you must use a format for
1648 <file>debian/changelog</file> which is supported by the most
1649 recent released version of <prgn>dpkg</prgn>.
1653 It is possible to use a format different from the standard
1654 one by providing a changelog parser for the format you wish
1655 to use. The parser must have an API compatible with that
1656 expected by <prgn>dpkg-genchanges</prgn> and
1657 <prgn>dpkg-gencontrol</prgn>, and it must not interact with
1660 If there is general interest in the new format, you should
1661 contact the <package>dpkg</package> maintainer to have the
1662 parser script for it included in the <prgn>dpkg</prgn>
1663 package. (You will need to agree that the parser and its
1664 manpage may be distributed under the GNU GPL, just as the rest
1665 of <prgn>dpkg</prgn> is.)
1672 <heading>Error trapping in makefiles</heading>
1675 When <prgn>make</prgn> invokes a command in a makefile
1676 (including your package's upstream makefiles and
1677 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1678 means that <prgn>sh</prgn>'s usual bad error handling
1679 properties apply: if you include a miniature script as one
1680 of the commands in your makefile you'll find that if you
1681 don't do anything about it then errors are not detected
1682 and <prgn>make</prgn> will blithely continue after
1687 Every time you put more than one shell command (this
1688 includes using a loop) in a makefile command you
1689 must make sure that errors are trapped. For
1690 simple compound commands, such as changing directory and
1691 then running a program, using <tt>&&</tt> rather
1692 than semicolon as a command separator is sufficient. For
1693 more complex commands including most loops and
1694 conditionals you should include a separate <tt>set -e</tt>
1695 command at the start of every makefile command that's
1696 actually one of these miniature shell scripts.
1700 <sect id="timestamps">
1701 <heading>Time Stamps</heading>
1703 Maintainers should preserve the modification times of the
1704 upstream source files in a package, as far as is reasonably
1706 The rationale is that there is some information conveyed
1707 by knowing the age of the file, for example, you could
1708 recognize that some documentation is very old by looking
1709 at the modification time, so it would be nice if the
1710 modification time of the upstream source would be
1716 <sect id="restrictions">
1717 <heading>Restrictions on objects in source packages</heading>
1720 The source package may not contain any hard links<footnote>
1722 This is not currently detected when building source
1723 packages, but only when extracting
1727 Hard links may be permitted at some point in the
1728 future, but would require a fair amount of
1731 </footnote>, device special files, sockets or setuid or
1732 setgid files.<footnote>
1733 Setgid directories are allowed.
1738 <sect id="debianrules">
1739 <heading>Main building script: <file>debian/rules</file></heading>
1742 This file must be an executable makefile, and contains the
1743 package-specific recipes for compiling the package and
1744 building binary package(s) from the source.
1748 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1749 so that it can be invoked by saying its name rather than
1750 invoking <prgn>make</prgn> explicitly.
1754 Since an interactive <file>debian/rules</file> script makes it
1755 impossible to auto-compile that package and also makes it
1756 hard for other people to reproduce the same binary
1757 package, all <em>required targets</em> MUST be
1758 non-interactive. At a minimum, required targets are the
1759 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1760 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1761 <em>binary-indep</em>, and <em>build</em>. It also follows
1762 that any target that these targets depend on must also be
1767 The targets are as follows (required unless stated otherwise):
1769 <tag><tt>build</tt></tag>
1772 The <tt>build</tt> target should perform all the
1773 configuration and compilation of the package.
1774 If a package has an interactive pre-build
1775 configuration routine, the Debianized source package
1776 must either be built after this has taken place (so
1777 that the binary package can be built without rerunning
1778 the configuration) or the configuration routine
1779 modified to become non-interactive. (The latter is
1780 preferable if there are architecture-specific features
1781 detected by the configuration routine.)
1785 For some packages, notably ones where the same
1786 source tree is compiled in different ways to produce
1787 two binary packages, the <tt>build</tt> target
1788 does not make much sense. For these packages it is
1789 good enough to provide two (or more) targets
1790 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1791 for each of the ways of building the package, and a
1792 <tt>build</tt> target that does nothing. The
1793 <tt>binary</tt> target will have to build the
1794 package in each of the possible ways and make the
1795 binary package out of each.
1799 The <tt>build</tt> target must not do anything
1800 that might require root privilege.
1804 The <tt>build</tt> target may need to run the
1805 <tt>clean</tt> target first - see below.
1809 When a package has a configuration and build routine
1810 which takes a long time, or when the makefiles are
1811 poorly designed, or when <tt>build</tt> needs to
1812 run <tt>clean</tt> first, it is a good idea to
1813 <tt>touch build</tt> when the build process is
1814 complete. This will ensure that if <tt>debian/rules
1815 build</tt> is run again it will not rebuild the whole
1817 Another common way to do this is for <tt>build</tt>
1818 to depend on <prgn>build-stamp</prgn> and to do
1819 nothing else, and for the <prgn>build-stamp</prgn>
1820 target to do the building and to <tt>touch
1821 build-stamp</tt> on completion. This is
1822 especially useful if the build routine creates a
1823 file or directory called <tt>build</tt>; in such a
1824 case, <tt>build</tt> will need to be listed as
1825 a phony target (i.e., as a dependency of the
1826 <tt>.PHONY</tt> target). See the documentation of
1827 <prgn>make</prgn> for more information on phony
1833 <tag><tt>build-arch</tt> (optional),
1834 <tt>build-indep</tt> (optional)
1838 A package may also provide both of the targets
1839 <tt>build-arch</tt> and <tt>build-indep</tt>.
1840 The <tt>build-arch</tt> target, if provided, should
1841 perform all the configuration and compilation required
1842 for producing all architecture-dependant binary packages
1843 (those packages for which the body of the
1844 <tt>Architecture</tt> field in <tt>debian/control</tt>
1845 is not <tt>all</tt>).
1846 Similarly, the <tt>build-indep</tt> target, if
1847 provided, should perform all the configuration and
1848 compilation required for producing all
1849 architecture-independent binary packages
1850 (those packages for which the body of the
1851 <tt>Architecture</tt> field in <tt>debian/control</tt>
1853 The <tt>build</tt> target should depend on those of the
1854 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1855 are provided in the rules file.
1859 If one or both of the targets <tt>build-arch</tt> and
1860 <tt>build-indep</tt> are not provided, then invoking
1861 <file>debian/rules</file> with one of the not-provided
1862 targets as arguments should produce a exit status code
1863 of 2. Usually this is provided automatically by make
1864 if the target is missing.
1868 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1869 must not do anything that might require root privilege.
1873 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1874 <tt>binary-indep</tt>
1878 The <tt>binary</tt> target must be all that is
1879 necessary for the user to build the binary package(s)
1880 produced from this source package. It is
1881 split into two parts: <prgn>binary-arch</prgn> builds
1882 the binary packages which are specific to a particular
1883 architecture, and <tt>binary-indep</tt> builds
1884 those which are not.
1887 <tt>binary</tt> may be (and commonly is) a target with
1888 no commands which simply depends on
1889 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1892 Both <tt>binary-*</tt> targets should depend on the
1893 <tt>build</tt> target, or on the appropriate
1894 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1895 provided, so that the package is built if it has not
1896 been already. It should then create the relevant
1897 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1898 make their control files and <prgn>dpkg-deb</prgn> to
1899 build them and place them in the parent of the top
1904 Both the <tt>binary-arch</tt> and
1905 <tt>binary-indep</tt> targets <em>must</em> exist.
1906 If one of them has nothing to do (which will always be
1907 the case if the source generates only a single binary
1908 package, whether architecture-dependent or not), it
1909 must still exist and must always succeed.
1913 The <tt>binary</tt> targets must be invoked as
1915 The <prgn>fakeroot</prgn> package often allows one
1916 to build a package correctly even without being
1922 <tag><tt>clean</tt></tag>
1925 This must undo any effects that the <tt>build</tt>
1926 and <tt>binary</tt> targets may have had, except
1927 that it should leave alone any output files created in
1928 the parent directory by a run of a <tt>binary</tt>
1933 If a <tt>build</tt> file is touched at the end of
1934 the <tt>build</tt> target, as suggested above, it
1935 should be removed as the first action that
1936 <tt>clean</tt> performs, so that running
1937 <tt>build</tt> again after an interrupted
1938 <tt>clean</tt> doesn't think that everything is
1943 The <tt>clean</tt> target may need to be
1944 invoked as root if <tt>binary</tt> has been
1945 invoked since the last <tt>clean</tt>, or if
1946 <tt>build</tt> has been invoked as root (since
1947 <tt>build</tt> may create directories, for
1952 <tag><tt>get-orig-source</tt> (optional)</tag>
1955 This target fetches the most recent version of the
1956 original source package from a canonical archive site
1957 (via FTP or WWW, for example), does any necessary
1958 rearrangement to turn it into the original source
1959 tar file format described below, and leaves it in the
1964 This target may be invoked in any directory, and
1965 should take care to clean up any temporary files it
1970 This target is optional, but providing it if
1971 possible is a good idea.
1977 The <tt>build</tt>, <tt>binary</tt> and
1978 <tt>clean</tt> targets must be invoked with the current
1979 directory being the package's top-level directory.
1984 Additional targets may exist in <file>debian/rules</file>,
1985 either as published or undocumented interfaces or for the
1986 package's internal use.
1990 The architectures we build on and build for are determined
1991 by <prgn>make</prgn> variables using the utility
1992 <qref id="pkg-dpkgarch"><prgn>dpkg-architecture</prgn></qref>.
1993 You can determine the
1994 Debian architecture and the GNU style architecture
1995 specification string for the build machine (the machine type
1996 we are building on) as well as for the host machine (the
1997 machine type we are building for). Here is a list of
1998 supported <prgn>make</prgn> variables:
1999 <list compact="compact">
2001 <tt>DEB_*_ARCH</tt> (the Debian architecture)
2004 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2005 specification string)
2008 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2009 <tt>DEB_*_GNU_TYPE</tt>)
2012 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2013 <tt>DEB_*_GNU_TYPE</tt>)
2015 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2016 the build machine or <tt>HOST</tt> for specification of the
2021 Backward compatibility can be provided in the rules file
2022 by setting the needed variables to suitable default
2023 values; please refer to the documentation of
2024 <prgn>dpkg-architecture</prgn> for details.
2028 It is important to understand that the <tt>DEB_*_ARCH</tt>
2029 string only determines which Debian architecture we are
2030 building on or for. It should not be used to get the CPU
2031 or system information; the GNU style variables should be
2036 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2037 <sect id="substvars">
2038 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2041 When <prgn>dpkg-gencontrol</prgn>,
2042 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2043 generate control files they perform variable substitutions
2044 on their output just before writing it. Variable
2045 substitutions have the form <tt>${<var>variable</var>}</tt>.
2046 The optional file <file>debian/substvars</file> contains
2047 variable substitutions to be used; variables can also be set
2048 directly from <file>debian/rules</file> using the <tt>-V</tt>
2049 option to the source packaging commands, and certain
2050 predefined variables are also available.
2054 The <file>debian/substvars</file> file is usually generated and
2055 modified dynamically by <file>debian/rules</file> targets, in
2056 which case it must be removed by the <tt>clean</tt> target.
2060 See <manref name="dpkg-source" section="1"> for full
2061 details about source variable substitutions, including the
2062 format of <file>debian/substvars</file>.</p>
2065 <sect id="debianfiles">
2066 <heading>Generated files list: <file>debian/files</file></heading>
2069 This file is not a permanent part of the source tree; it
2070 is used while building packages to record which files are
2071 being generated. <prgn>dpkg-genchanges</prgn> uses it
2072 when it generates a <file>.changes</file> file.
2076 It should not exist in a shipped source package, and so it
2077 (and any backup files or temporary files such as
2078 <file>files.new</file><footnote>
2079 <file>files.new</file> is used as a temporary file by
2080 <prgn>dpkg-gencontrol</prgn> and
2081 <prgn>dpkg-distaddfile</prgn> - they write a new
2082 version of <tt>files</tt> here before renaming it,
2083 to avoid leaving a corrupted copy if an error
2085 </footnote>) should be removed by the
2086 <tt>clean</tt> target. It may also be wise to
2087 ensure a fresh start by emptying or removing it at the
2088 start of the <tt>binary</tt> target.
2092 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2093 package, it adds an entry to <file>debian/files</file> for the
2094 <file>.deb</file> file that will be created when <tt>dpkg-deb
2095 --build</tt> is run for that binary package. So for most
2096 packages all that needs to be done with this file is to
2097 delete it in the <tt>clean</tt> target.
2101 If a package upload includes files besides the source
2102 package and any binary packages whose control files were
2103 made with <prgn>dpkg-gencontrol</prgn> then they should be
2104 placed in the parent of the package's top-level directory
2105 and <prgn>dpkg-distaddfile</prgn> should be called to add
2106 the file to the list in <file>debian/files</file>.</p>
2112 <chapt id="controlfields">
2113 <heading>Control files and their fields</heading>
2116 The package management system manipulates data represented in
2117 a common format, known as <em>control data</em>, stored in
2118 <em>control files</em>.
2119 Control files are used for source packages, binary packages and
2120 the <file>.changes</file> files which control the installation
2121 of uploaded files<footnote>
2122 <prgn>dpkg</prgn>'s internal databases are in a similar
2127 <sect id="controlsyntax">
2128 <heading>Syntax of control files</heading>
2131 A control file consists of one or more paragraphs of
2133 The paragraphs are also sometimes referred to as stanzas.
2135 The paragraphs are separated by blank lines. Some control
2136 files allow only one paragraph; others allow several, in
2137 which case each paragraph usually refers to a different
2138 package. (For example, in source packages, the first
2139 paragraph refers to the source package, and later paragraphs
2140 refer to binary packages generated from the source.)
2144 Each paragraph consists of a series of data fields; each
2145 field consists of the field name, followed by a colon and
2146 then the data/value associated with that field. It ends at
2147 the end of the line. Horizontal whitespace (spaces and
2148 tabs) may occur immediately before or after the value and is
2149 ignored there; it is conventional to put a single space
2150 after the colon. For example, a field might be:
2151 <example compact="compact">
2154 the field name is <tt>Package</tt> and the field value
2159 Some fields' values may span several lines; in this case
2160 each continuation line must start with a space or a tab.
2161 Any trailing spaces or tabs at the end of individual
2162 lines of a field value are ignored.
2166 Except where otherwise stated, only a single line of data is
2167 allowed and whitespace is not significant in a field body.
2168 Whitespace must not appear inside names (of packages,
2169 architectures, files or anything else) or version numbers,
2170 or between the characters of multi-character version
2175 Field names are not case-sensitive, but it is usual to
2176 capitalize the field names using mixed case as shown below.
2180 Blank lines, or lines consisting only of spaces and tabs,
2181 are not allowed within field values or between fields - that
2182 would mean a new paragraph.
2187 <sect id="sourcecontrolfiles">
2188 <heading>Source package control files -- <file>debian/control</file></heading>
2191 The <file>debian/control</file> file contains the most vital
2192 (and version-independent) information about the source package
2193 and about the binary packages it creates.
2197 The first paragraph of the control file contains information about
2198 the source package in general. The subsequent sets each describe a
2199 binary package that the source tree builds.
2203 The fields in the general paragraph (the first one, for the source
2206 <list compact="compact">
2207 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2208 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2209 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2210 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2211 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2212 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2217 The fields in the binary package paragraphs are:
2219 <list compact="compact">
2220 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2221 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2222 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2223 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2224 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2225 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2226 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2231 The syntax and semantics of the fields are described below.
2237 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2238 generate control files for binary packages (see below), by
2239 <prgn>dpkg-genchanges</prgn> to generate the
2240 <tt>.changes</tt> file to accompany the upload, and by
2241 <prgn>dpkg-source</prgn> when it creates the <file>.dsc</file>
2242 source control file as part of a source archive.
2246 The fields here may contain variable references - their
2247 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2248 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2249 when they generate output control files.
2250 See <ref id="substvars"> for details.
2255 <sect id="binarycontrolfiles">
2256 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2259 The <file>DEBIAN/control</file> file contains the most vital
2260 (and version-dependent) information about a binary package.
2264 The fields in this file are:
2266 <list compact="compact">
2267 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2268 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2269 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2270 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2271 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2272 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2273 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2274 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2275 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2276 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2277 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2282 <sect id="debiansourcecontrolfiles">
2283 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2286 This file contains a series of fields, identified and
2287 separated just like the fields in the control file of
2288 a binary package. The fields are listed below; their
2289 syntax is described above, in <ref id="pkg-controlfields">.
2291 <list compact="compact">
2292 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2293 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2294 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2295 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2296 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2297 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2298 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2299 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2304 The source package control file is generated by
2305 <prgn>dpkg-source</prgn> when it builds the source
2306 archive, from other files in the source package,
2307 described above. When unpacking, it is checked against
2308 the files and directories in the other parts of the
2314 <sect id="debianchangesfiles">
2315 <heading>Debian changes files -- <file>.changes</file></heading>
2318 The .changes files are used by the Debian archive maintenance
2319 software to process updates to packages. They contain one
2320 paragraph which contains information from the
2321 <tt>debian/control</tt> file and other data about the
2322 source package gathered via <tt>debian/changelog</tt>
2323 and <tt>debian/rules</tt>.
2327 The fields in this file are:
2329 <list compact="compact">
2330 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2331 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2332 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2333 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2334 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2335 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2336 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2337 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2338 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2339 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2340 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2341 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2342 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2343 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2348 <sect id="controlfieldslist">
2349 <heading>List of fields</heading>
2351 <sect1 id="f-Source">
2352 <heading><tt>Source</tt></heading>
2355 This field identifies the source package name.
2359 In a main source control information, a <file>.changes</file>
2360 or a <file>.dsc</file> file this may contain only the name
2361 of the source package.
2365 In the control file of a binary package it may be followed
2366 by a version number in parentheses<footnote>
2367 It is customary to leave a space after the package name
2368 if a version number is specified.
2370 This version number may be omitted (and is, by
2371 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2372 the <tt>Version</tt> field of the binary package in
2373 question. The field itself may be omitted from a binary
2374 package control file when the source package has the same
2375 name and version as the binary package.
2379 <sect1 id="f-Maintainer">
2380 <heading><tt>Maintainer</tt></heading>
2383 The package maintainer's name and email address. The name
2384 should come first, then the email address inside angle
2385 brackets <tt><></tt> (in RFC822 format).
2389 If the maintainer's name contains a full stop then the
2390 whole field will not work directly as an email address due
2391 to a misfeature in the syntax specified in RFC822; a
2392 program using this field as an address must check for this
2393 and correct the problem if necessary (for example by
2394 putting the name in round brackets and moving it to the
2395 end, and bringing the email address forward).
2399 <sect1 id="f-Changed-By">
2400 <heading><tt>Changed-By</tt></heading>
2403 The name and email address of the person who changed the
2404 said package. Usually the name of the maintainer.
2405 All the rules for the Maintainer field apply here, too.
2409 <sect1 id="f-Section">
2410 <heading><tt>Section</tt></heading>
2413 This field specifies an application area into which the package
2414 has been classified. See <ref id="subsections">.
2418 When it appears in the <file>debian/control</file> file,
2419 it gives the value for the subfield of the same name in
2420 the <tt>Files</tt> field of the <file>.changes</file> file.
2421 It also gives the default for the same field in the binary
2426 By default, <prgn>dpkg-gencontrol</prgn> does not include this
2427 field in the control file of a binary package - use the
2428 <tt>-is</tt> (or <tt>-isp</tt>) options to achieve this effect.
2432 <sect1 id="f-Priority">
2433 <heading><tt>Priority</tt></heading>
2436 This field represents how important that it is that the user
2437 have the package installed. See <ref id="priorities">.
2441 When it appears in the <file>debian/control</file> file,
2442 it gives the value for the subfield of the same name in
2443 the <tt>Files</tt> field of the <file>.changes</file> file.
2444 It also gives the default for the same field in the binary
2449 By default, <prgn>dpkg-gencontrol</prgn> does not include this
2450 field in the control file of a binary package - use the
2451 <tt>-ip</tt> (or <tt>-isp</tt>) options to achieve this effect.
2455 <sect1 id="f-Package">
2456 <heading><tt>Package</tt></heading>
2459 The name of the binary package.
2463 Package names must consist only of lower case letters
2464 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
2465 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
2466 They must be at least two characters long and must start
2467 with an alphanumeric character.
2471 <sect1 id="f-Architecture">
2472 <heading><tt>Architecture</tt></heading>
2475 This is the architecture string; it is a single word for
2476 the Debian architecture. The special value <tt>all</tt>
2477 indicates that the package is architecture-independent.
2481 In the main <file>debian/control</file> file in the source
2482 package, or in the source package control file
2483 <file>.dsc</file>, a list of architectures (separated by
2484 spaces) is also allowed, as is the special value
2485 <tt>any</tt>. A list indicates that the source will build
2486 an architecture-dependent package, and will only work
2487 correctly on the listed architectures. <tt>any</tt>
2488 indicates that though the source package isn't dependent
2489 on any particular architecture and should compile fine on
2490 any one, the binary package(s) produced are not
2491 architecture-independent but will instead be specific to
2492 whatever the current build architecture is.
2496 In a <file>.changes</file> file the <tt>Architecture</tt>
2497 field lists the architecture(s) of the package(s)
2498 currently being uploaded. This will be a list; if the
2499 source for the package is being uploaded too the special
2500 entry <tt>source</tt> is also present.
2504 See <ref id="debianrules"> for information how to get the
2505 architecture for the build process.
2509 <sect1 id="f-Essential">
2510 <heading><tt>Essential</tt></heading>
2513 This is a boolean field which may occur only in the
2514 control file of a binary package or in a per-package fields
2515 paragraph of a main source control data file.
2519 If set to <tt>yes</tt> then the package management system
2520 will refuse to remove the package (upgrading and replacing
2521 it is still possible). The other possible value is <tt>no</tt>,
2522 which is the same as not having the field at all.
2527 <heading>Package interrelationship fields:
2528 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2529 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Conflicts</tt>,
2530 <tt>Provides</tt>, <tt>Replaces</tt>
2534 These fields describe the package's relationships with
2535 other packages. Their syntax and semantics are described
2536 in <ref id="relationships">.</p>
2539 <sect1 id="f-Standards-Version">
2540 <heading><tt>Standards-Version</tt></heading>
2543 The most recent version of the standards (the policy
2544 manual and associated texts) with which the package
2549 The version number has four components: major and minor
2550 version number and major and minor patch level. When the
2551 standards change in a way that requires every package to
2552 change the major number will be changed. Significant
2553 changes that will require work in many packages will be
2554 signaled by a change to the minor number. The major patch
2555 level will be changed for any change to the meaning of the
2556 standards, however small; the minor patch level will be
2557 changed when only cosmetic, typographical or other edits
2558 are made which neither change the meaning of the document
2559 nor affect the contents of packages.
2563 Thus only the first three components of the policy version
2564 are significant in the <em>Standards-Version</em> control
2565 field, and so either these three components or the all
2566 four components may be specified.<footnote>
2567 In the past, people specified the full version number
2568 in the Standards-Version field, for example "2.3.0.0".
2569 Since minor patch-level changes don't introduce new
2570 policy, it was thought it would be better to relax
2571 policy and only require the first 3 components to be
2572 specified, in this example "2.3.0". All four
2573 components may still be used if someone wishes to do so.
2579 <sect1 id="f-Version">
2580 <heading><tt>Version</tt></heading>
2583 The version number of a package. The format is:
2584 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2588 The three components here are:
2590 <tag><var>epoch</var></tag>
2593 This is a single (generally small) unsigned integer. It
2594 may be omitted, in which case zero is assumed. If it is
2595 omitted then the <var>upstream_version</var> may not
2600 It is provided to allow mistakes in the version numbers
2601 of older versions of a package, and also a package's
2602 previous version numbering schemes, to be left behind.
2606 <tag><var>upstream_version</var></tag>
2609 This is the main part of the version number. It is
2610 usually the version number of the original ("upstream")
2611 package from which the <file>.deb</file> file has been made,
2612 if this is applicable. Usually this will be in the same
2613 format as that specified by the upstream author(s);
2614 however, it may need to be reformatted to fit into the
2615 package management system's format and comparison
2620 The comparison behavior of the package management system
2621 with respect to the <var>upstream_version</var> is
2622 described below. The <var>upstream_version</var>
2623 portion of the version number is mandatory.
2627 The <var>upstream_version</var> may contain only
2628 alphanumerics<footnote>
2629 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2631 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2632 <tt>:</tt> (full stop, plus, hyphen, colon) and should
2633 start with a digit. If there is no
2634 <var>debian_revision</var> then hyphens are not allowed;
2635 if there is no <var>epoch</var> then colons are not
2640 <tag><var>debian_revision</var></tag>
2643 This part of the version number specifies the version of
2644 the Debian package based on the upstream version. It
2645 may contain only alphanumerics and the characters
2646 <tt>+</tt> and <tt>.</tt> (plus and full stop) and is
2647 compared in the same way as the
2648 <var>upstream_version</var> is.
2652 It is optional; if it isn't present then the
2653 <var>upstream_version</var> may not contain a hyphen.
2654 This format represents the case where a piece of
2655 software was written specifically to be turned into a
2656 Debian package, and so there is only one "debianization"
2657 of it and therefore no revision indication is required.
2661 It is conventional to restart the
2662 <var>debian_revision</var> at <tt>1</tt> each time the
2663 <var>upstream_version</var> is increased.
2667 The package management system will break the version
2668 number apart at the last hyphen in the string (if there
2669 is one) to determine the <var>upstream_version</var> and
2670 <var>debian_revision</var>. The absence of a
2671 <var>debian_revision</var> compares earlier than the
2672 presence of one (but note that the
2673 <var>debian_revision</var> is the least significant part
2674 of the version number).
2681 The <var>upstream_version</var> and <var>debian_revision</var>
2682 parts are compared by the package management system using the
2687 The strings are compared from left to right.
2691 First the initial part of each string consisting entirely of
2692 non-digit characters is determined. These two parts (one of
2693 which may be empty) are compared lexically. If a difference
2694 is found it is returned. The lexical comparison is a
2695 comparison of ASCII values modified so that all the letters
2696 sort earlier than all the non-letters.
2700 Then the initial part of the remainder of each string which
2701 consists entirely of digit characters is determined. The
2702 numerical values of these two parts are compared, and any
2703 difference found is returned as the result of the comparison.
2704 For these purposes an empty string (which can only occur at
2705 the end of one or both version strings being compared) counts
2710 These two steps (comparing and removing initial non-digit
2711 strings and initial digit strings) are repeated until a
2712 difference is found or both strings are exhausted.
2716 Note that the purpose of epochs is to allow us to leave behind
2717 mistakes in version numbering, and to cope with situations
2718 where the version numbering scheme changes. It is
2719 <em>not</em> intended to cope with version numbers containing
2720 strings of letters which the package management system cannot
2721 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
2722 silly orderings (the author of this manual has heard of a
2723 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
2724 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
2725 <tt>2</tt> and so forth).
2729 <sect1 id="f-Description">
2730 <heading><tt>Description</tt></heading>
2733 In a source or binary control file, the <tt>Description</tt>
2734 field contains a description of the binary package, consisting
2735 of two parts, the synopsis or the short description, and the
2736 long description. The field's format is as follows:
2741 Description: <single line synopsis>
2742 <extended description over several lines>
2747 The lines in the extended description can have these formats:
2753 Those starting with a single space are part of a paragraph.
2754 Successive lines of this form will be word-wrapped when
2755 displayed. The leading space will usually be stripped off.
2759 Those starting with two or more spaces. These will be
2760 displayed verbatim. If the display cannot be panned
2761 horizontally, the displaying program will linewrap them "hard"
2762 (i.e., without taking account of word breaks). If it can they
2763 will be allowed to trail off to the right. None, one or two
2764 initial spaces may be deleted, but the number of spaces
2765 deleted from each line will be the same (so that you can have
2766 indenting work correctly, for example).
2770 Those containing a single space followed by a single full stop
2771 character. These are rendered as blank lines. This is the
2772 <em>only</em> way to get a blank line<footnote>
2773 Completely empty lines will not be rendered as blank lines.
2774 Instead, they will cause the parser to think you're starting
2775 a whole new record in the control file, and will therefore
2776 likely abort with an error.
2781 Those containing a space, a full stop and some more characters.
2782 These are for future expansion. Do not use them.
2788 Do not use tab characters. Their effect is not predictable.
2792 See <ref id="descriptions"> for further information on this.
2796 In a <file>.changes</file> file, the <tt>Description</tt> field
2797 contains a summary of the descriptions for the packages being
2802 The part of the field before the first newline is empty;
2803 thereafter each line has the name of a binary package and
2804 the summary description line from that binary package.
2805 Each line is indented by one space.
2810 <sect1 id="f-Distribution">
2811 <heading><tt>Distribution</tt></heading>
2814 In a <file>.changes</file> file or parsed changelog output
2815 this contains the (space-separated) name(s) of the
2816 distribution(s) where this version of the package should
2817 be installed. Valid distributions are determined by the
2818 archive maintainers.<footnote>
2819 Current distribution names are:
2820 <taglist compact="compact">
2821 <tag><em>stable</em></tag>
2823 This is the current "released" version of Debian
2824 GNU/Linux. Once the distribution is
2825 <em>stable</em> only security fixes and other
2826 major bug fixes are allowed. When changes are
2827 made to this distribution, the release number is
2828 increased (for example: 2.2r1 becomes 2.2r2 then
2832 <tag><em>unstable</em></tag>
2834 This distribution value refers to the
2835 <em>developmental</em> part of the Debian
2836 distribution tree. New packages, new upstream
2837 versions of packages and bug fixes go into the
2838 <em>unstable</em> directory tree. Download from
2839 this distribution at your own risk.
2842 <tag><em>testing</em></tag>
2844 This distribution value refers to the
2845 <em>testing</em> part of the Debian distribution
2846 tree. It receives its packages from the
2847 unstable distribution after a short time lag to
2848 ensure that there are no major issues with the
2849 unstable packages. It is less prone to breakage
2850 than unstable, but still risky. It is not
2851 possible to upload packages directly to
2855 <tag><em>frozen</em></tag>
2857 From time to time, the <em>testing</em>
2858 distribution enters a state of "code-freeze" in
2859 anticipation of release as a <em>stable</em>
2860 version. During this period of testing only
2861 fixes for existing or newly-discovered bugs will
2862 be allowed. The exact details of this stage are
2863 determined by the Release Manager.
2866 <tag><em>experimental</em></tag>
2868 The packages with this distribution value are
2869 deemed by their maintainers to be high
2870 risk. Oftentimes they represent early beta or
2871 developmental packages from various sources that
2872 the maintainers want people to try, but are not
2873 ready to be a part of the other parts of the
2874 Debian distribution tree. Download at your own
2880 You should list <em>all</em> distributions that the
2881 package should be installed into.
2885 More information is available in the Debian Developer's
2886 Reference, section "The Debian archive".
2893 <heading><tt>Date</tt></heading>
2896 This field includes the date the package was built or last edited.
2900 The value of this field is usually extracted from the
2901 <file>debian/changelog</file> file - see
2902 <ref id="dpkgchangelog">).
2906 <sect1 id="f-Format">
2907 <heading><tt>Format</tt></heading>
2910 This field specifies a format revision for the file.
2911 The most current format described in the Policy Manual
2912 is version <strong>1.5</strong>. The syntax of the
2913 format value is the same as that of a package version
2914 number except that no epoch or Debian revision is allowed
2915 - see <ref id="f-Version">.
2919 <sect1 id="f-Urgency">
2920 <heading><tt>Urgency</tt></heading>
2923 This is a description of how important it is to upgrade to
2924 this version from previous ones. It consists of a single
2925 keyword usually taking one of the values <tt>low</tt>,
2926 <tt>medium</tt> or <tt>high</tt> (not case-sensitive)
2927 followed by an optional commentary (separated by a space)
2928 which is usually in parentheses. For example:
2931 Urgency: low (HIGH for users of diversions)
2937 The value of this field is usually extracted from the
2938 <file>debian/changelog</file> file - see
2939 <ref id="dpkgchangelog">.
2943 <sect1 id="f-Changes">
2944 <heading><tt>Changes</tt></heading>
2947 This field contains the human-readable changes data, describing
2948 the differences between the last version and the current one.
2952 There should be nothing in this field before the first
2953 newline; all the subsequent lines must be indented by at
2954 least one space; blank lines must be represented by a line
2955 consiting only of a space and a full stop.
2959 The value of this field is usually extracted from the
2960 <file>debian/changelog</file> file - see
2961 <ref id="dpkgchangelog">).
2965 Each version's change information should be preceded by a
2966 "title" line giving at least the version, distribution(s)
2967 and urgency, in a human-readable way.
2971 If data from several versions is being returned the entry
2972 for the most recent version should be returned first, and
2973 entries should be separated by the representation of a
2974 blank line (the "title" line may also be followed by the
2975 representation of blank line).
2979 <sect1 id="f-Binary">
2980 <heading><tt>Binary</tt></heading>
2983 This field is a list of binary packages.
2987 When it appears in the <file>.dsc</file> file it is the list
2988 of binary packages which a source package can produce. It
2989 does not necessarily produce all of these binary packages
2990 for every architecture. The source control file doesn't
2991 contain details of which architectures are appropriate for
2992 which of the binary packages.
2996 When it appears in a <file>.changes</file> file it lists the
2997 names of the binary packages actually being uploaded.
3001 The syntax is a list of binary packages separated by
3003 A space after each comma is conventional.
3004 </footnote>. Currently the packages must be separated using
3005 only spaces in the <file>.changes</file> file.
3009 <sect1 id="f-Installed-Size">
3010 <heading><tt>Installed-Size</tt></heading>
3013 This field appears in the control files of binary
3014 packages, and in the <file>Packages</file> files. It gives
3015 the total amount of disk space required to install the
3020 The disk space is represented in kilobytes as a simple
3025 <sect1 id="f-Files">
3026 <heading><tt>Files</tt></heading>
3029 This field contains a list of files with information about
3030 each one. The exact information and syntax varies with
3031 the context. In all cases the part of the field
3032 contents on the same line as the field name is empty. The
3033 remainder of the field is one line per file, each line
3034 being indented by one space and containing a number of
3035 sub-fields separated by spaces.
3039 In the <file>.dsc</file> file, each line contains the MD5
3040 checksum, size and filename of the tar file and (if applicable)
3041 diff file which make up the remainder of the source
3043 That is, the parts which are not the <tt>.dsc</tt>.
3045 The exact forms of the filenames are described
3046 in <ref id="pkg-sourcearchives">.
3050 In the <file>.changes</file> file this contains one line per
3051 file being uploaded. Each line contains the MD5 checksum,
3052 size, section and priority and the filename.
3053 The <qref id="f-Section">section</qref>
3054 and <qref id="f-Priority">priority</qref>
3055 are the values of the corresponding fields in
3056 the main source control file. If no section or priority is
3057 specified then <tt>-</tt> should be used, though section
3058 and priority values must be specified for new packages to
3059 be installed properly.
3063 The special value <tt>byhand</tt> for the section in a
3064 <tt>.changes</tt> file indicates that the file in question
3065 is not an ordinary package file and must by installed by
3066 hand by the distribution maintainers. If the section is
3067 <tt>byhand</tt> the priority should be <tt>-</tt>.
3071 If a new Debian revision of a package is being shipped and
3072 no new original source archive is being distributed the
3073 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3074 entry for the original source archive
3075 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
3076 but the <file>.changes</file> file should leave it out. In
3077 this case the original source archive on the distribution
3078 site must match exactly, byte-for-byte, the original
3079 source archive which was used to generate the
3080 <file>.dsc</file> file and diff which are being uploaded.</p>
3083 <sect1 id="f-Closes">
3084 <heading><tt>Closes</tt></heading>
3087 A space-separated list of bug report numbers that the upload
3088 governed by the .changes file closes.
3095 <heading>User-defined fields</heading>
3098 Additional user-defined fields may be added to the
3099 source package control file. Such fields will be
3100 ignored, and not copied to (for example) binary or
3101 source package control files or upload control files.
3105 If you wish to add additional unsupported fields to
3106 these output files you should use the mechanism
3111 Fields in the main source control information file with
3112 names starting <tt>X</tt>, followed by one or more of
3113 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3114 be copied to the output files. Only the part of the
3115 field name after the hyphen will be used in the output
3116 file. Where the letter <tt>B</tt> is used the field
3117 will appear in binary package control files, where the
3118 letter <tt>S</tt> is used in source package control
3119 files and where <tt>C</tt> is used in upload control
3120 (<tt>.changes</tt>) files.
3124 For example, if the main source information control file
3127 XBS-Comment: I stand between the candle and the star.
3129 then the binary and source package control files will contain the
3132 Comment: I stand between the candle and the star.
3141 <chapt id="maintainerscripts">
3142 <heading>Package maintainer scripts and installation procedure</heading>
3145 <heading>Introduction to package maintainer scripts</heading>
3148 It is possible to supply scripts as part of a package which
3149 the package management system will run for you when your
3150 package is installed, upgraded or removed.
3154 These scripts are the files <prgn>preinst</prgn>,
3155 <prgn>postinst</prgn>, <prgn>prerm</prgn> and <prgn>postrm</prgn> in the
3156 control area of the package. They must be proper executable
3157 files; if they are scripts (which is recommended), they must
3158 start with the usual <tt>#!</tt> convention. They should be
3159 readable and executable by anyone, and not world-writable.
3163 The package management system looks at the exit status from
3164 these scripts. It is important that they exit with a
3165 non-zero status if there is an error, so that the package
3166 management system can stop its processing. For shell
3167 scripts this means that you <em>almost always</em> need to
3168 use <tt>set -e</tt> (this is usually true when writing shell
3169 scripts, in fact). It is also important, of course, that
3170 they don't exit with a non-zero status if everything went
3175 When a package is upgraded a combination of the scripts from
3176 the old and new packages is called during the upgrade
3177 procedure. If your scripts are going to be at all
3178 complicated you need to be aware of this, and may need to
3179 check the arguments to your scripts.
3183 Broadly speaking the <prgn>preinst</prgn> is called before
3184 (a particular version of) a package is installed, and the
3185 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3186 before (a version of) a package is removed and the
3187 <prgn>postrm</prgn> afterwards.
3191 Programs called from maintainer scripts should not normally
3192 have a path prepended to them. Before installation is
3193 started, the package management system checks to see if the
3194 programs <prgn>ldconfig</prgn>,
3195 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3196 and <prgn>update-rc.d</prgn> can be found via the
3197 <tt>PATH</tt> environment variable. Those programs, and any
3198 other program that one would expect to be on the
3199 <tt>PATH</tt>, should thus be invoked without an absolute
3200 pathname. Maintainer scripts should also not reset the
3201 <tt>PATH</tt>, though they might choose to modify it by
3202 prepending or appending package-specific directories. These
3203 considerations really apply to all shell scripts.</p>
3206 <sect id="idempotency">
3207 <heading>Maintainer scripts Idempotency</heading>
3210 It is necessary for the error recovery procedures that the
3211 scripts be idempotent. This means that if it is run
3212 successfully, and then it is called again, it doesn't bomb
3213 out or cause any harm, but just ensures that everything is
3214 the way it ought to be. If the first call failed, or
3215 aborted half way through for some reason, the second call
3216 should merely do the things that were left undone the first
3217 time, if any, and exit with a success status if everything
3219 This is so that if an error occurs, the user interrupts
3220 <prgn>dpkg</prgn> or some other unforeseen circumstance
3221 happens you don't leave the user with a badly-broken
3222 package when <prgn>dpkg</prgn> attempts to repeat the
3228 <sect id="controllingterminal">
3229 <heading>Controlling terminal for maintainer scripts</heading>
3232 The maintainer scripts are guaranteed to run with a
3233 controlling terminal and can interact with the user.
3234 If they need to prompt for passwords, do full-screen
3235 interaction or something similar you should do these
3236 things to and from <file>/dev/tty</file>, since
3237 <prgn>dpkg</prgn> will at some point redirect scripts'
3238 standard input and output so that it can log the
3239 installation process. Likewise, because these scripts
3240 may be executed with standard output redirected into a
3241 pipe for logging purposes, Perl scripts should set
3242 unbuffered output by setting <tt>$|=1</tt> so that the
3243 output is printed immediately rather than being
3248 Each script should return a zero exit status for
3249 success, or a nonzero one for failure.
3253 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3258 <list compact="compact">
3260 <var>new-preinst</var> <tt>install</tt>
3263 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3266 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3269 <var>old-preinst</var> <tt>abort-upgrade</tt>
3270 <var>new-version</var>
3275 <list compact="compact">
3277 <var>postinst</var> <tt>configure</tt>
3278 <var>most-recently-configured-version</var>
3281 <var>old-postinst</var> <tt>abort-upgrade</tt>
3282 <var>new-version</var>
3285 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3286 <tt>in-favour</tt> <var>package</var>
3287 <var>new-version</var>
3290 <var>deconfigured's-postinst</var>
3291 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3292 <var>failed-install-package</var> <var>version</var>
3293 <tt>removing</tt> <var>conflicting-package</var>
3299 <list compact="compact">
3301 <var>prerm</var> <tt>remove</tt>
3304 <var>old-prerm</var> <tt>upgrade</tt>
3305 <var>new-version</var>
3308 <var>new-prerm</var> <tt>failed-upgrade</tt>
3309 <var>old-version</var>
3312 <var>conflictor's-prerm</var> <tt>remove</tt>
3313 <tt>in-favour</tt> <var>package</var>
3314 <var>new-version</var>
3317 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3318 <tt>in-favour</tt> <var>package-being-installed</var>
3319 <var>version</var> <tt>removing</tt>
3320 <var>conflicting-package</var>
3326 <list compact="compact">
3328 <var>postrm</var> <tt>remove</tt>
3331 <var>postrm</var> <tt>purge</tt>
3334 <var>old-postrm</var> <tt>upgrade</tt>
3335 <var>new-version</var>
3338 <var>new-postrm</var> <tt>failed-upgrade</tt>
3339 <var>old-version</var>
3342 <var>new-postrm</var> <tt>abort-install</tt>
3345 <var>new-postrm</var> <tt>abort-install</tt>
3346 <var>old-version</var>
3349 <var>new-postrm</var> <tt>abort-upgrade</tt>
3350 <var>old-version</var>
3353 <var>disappearer's-postrm</var> <tt>disappear</tt>
3354 <var>overwriter</var>
3355 <var>overwriter-version</var>
3361 <sect id="unpackphase">
3362 <heading>Details of unpack phase of installation or upgrade</heading>
3365 The procedure on installation/upgrade/overwrite/disappear
3366 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3367 stage of <tt>dpkg --install</tt>) is as follows. In each
3368 case, if a major error occurs (unless listed below) the
3369 actions are, in general, run backwards - this means that the
3370 maintainer scripts are run with different arguments in
3371 reverse order. These are the "error unwind" calls listed
3378 If a version of the package is already installed, call
3379 <example compact="compact">
3380 <var>old-prerm</var> upgrade <var>new-version</var>
3384 If the script runs but exits with a non-zero
3385 exit status, <prgn>dpkg</prgn> will attempt:
3386 <example compact="compact">
3387 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3389 Error unwind, for both the above cases:
3390 <example compact="compact">
3391 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3398 If a "conflicting" package is being removed at the same time:
3401 If any packages depended on that conflicting
3402 package and <tt>--auto-deconfigure</tt> is
3403 specified, call, for each such package:
3404 <example compact="compact">
3405 <var>deconfigured's-prerm</var> deconfigure \
3406 in-favour <var>package-being-installed</var> <var>version</var> \
3407 removing <var>conflicting-package</var> <var>version</var>
3410 <example compact="compact">
3411 <var>deconfigured's-postinst</var> abort-deconfigure \
3412 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3413 removing <var>conflicting-package</var> <var>version</var>
3415 The deconfigured packages are marked as
3416 requiring configuration, so that if
3417 <tt>--install</tt> is used they will be
3418 configured again if possible.
3421 To prepare for removal of the conflicting package, call:
3422 <example compact="compact">
3423 <var>conflictor's-prerm</var> remove \
3424 in-favour <var>package</var> <var>new-version</var>
3427 <example compact="compact">
3428 <var>conflictor's-postinst</var> abort-remove \
3429 in-favour <var>package</var> <var>new-version</var>
3438 If the package is being upgraded, call:
3439 <example compact="compact">
3440 <var>new-preinst</var> upgrade <var>old-version</var>
3444 Otherwise, if the package had some configuration
3445 files from a previous version installed (i.e., it
3446 is in the "configuration files only" state):
3447 <example compact="compact">
3448 <var>new-preinst</var> install <var>old-version</var>
3452 Otherwise (i.e., the package was completely purged):
3453 <example compact="compact">
3454 <var>new-preinst</var> install
3456 Error unwind actions, respectively:
3457 <example compact="compact">
3458 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3459 <var>new-postrm</var> abort-install <var>old-version</var>
3460 <var>new-postrm</var> abort-install
3468 The new package's files are unpacked, overwriting any
3469 that may be on the system already, for example any
3470 from the old version of the same package or from
3471 another package. Backups of the old files are kept
3472 temporarily, and if anything goes wrong the package
3473 management system will attempt to put them back as
3474 part of the error unwind.
3478 It is an error for a package to contain files which
3479 are on the system in another package, unless
3480 <tt>Replaces</tt> is used (see <ref id="replaces">).
3482 The following paragraph is not currently the case:
3483 Currently the <tt>- - force-overwrite</tt> flag is
3484 enabled, downgrading it to a warning, but this may not
3490 It is a more serious error for a package to contain a
3491 plain file or other kind of non-directory where another
3492 package has a directory (again, unless
3493 <tt>Replaces</tt> is used). This error can be
3494 overridden if desired using
3495 <tt>--force-overwrite-dir</tt>, but this is not
3500 Packages which overwrite each other's files produce
3501 behavior which, though deterministic, is hard for the
3502 system administrator to understand. It can easily
3503 lead to "missing" programs if, for example, a package
3504 is installed which overwrites a file from another
3505 package, and is then removed again.<footnote>
3506 Part of the problem is due to what is arguably a
3507 bug in <prgn>dpkg</prgn>.
3512 A directory will never be replaced by a symbolic link
3513 to a directory or vice versa; instead, the existing
3514 state (symlink or not) will be left alone and
3515 <prgn>dpkg</prgn> will follow the symlink if there is
3524 If the package is being upgraded, call
3525 <example compact="compact">
3526 <var>old-postrm</var> upgrade <var>new-version</var>
3530 If this fails, <prgn>dpkg</prgn> will attempt:
3531 <example compact="compact">
3532 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3534 Error unwind, for both cases:
3535 <example compact="compact">
3536 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3543 This is the point of no return - if
3544 <prgn>dpkg</prgn> gets this far, it won't back off
3545 past this point if an error occurs. This will
3546 leave the package in a fairly bad state, which
3547 will require a successful re-installation to clear
3548 up, but it's when <prgn>dpkg</prgn> starts doing
3549 things that are irreversible.
3554 Any files which were in the old version of the package
3555 but not in the new are removed.
3559 The new file list replaces the old.
3563 The new maintainer scripts replace the old.
3567 Any packages all of whose files have been overwritten
3568 during the installation, and which aren't required for
3569 dependencies, are considered to have been removed.
3570 For each such package
3573 <prgn>dpkg</prgn> calls:
3574 <example compact="compact">
3575 <var>disappearer's-postrm</var> disappear \
3576 <var>overwriter</var> <var>overwriter-version</var>
3580 The package's maintainer scripts are removed.
3583 It is noted in the status database as being in a
3584 sane state, namely not installed (any conffiles
3585 it may have are ignored, rather than being
3586 removed by <prgn>dpkg</prgn>). Note that
3587 disappearing packages do not have their prerm
3588 called, because <prgn>dpkg</prgn> doesn't know
3589 in advance that the package is going to
3596 Any files in the package we're unpacking that are also
3597 listed in the file lists of other packages are removed
3598 from those lists. (This will lobotomize the file list
3599 of the "conflicting" package if there is one.)
3603 The backup files made during installation, above, are
3609 The new package's status is now sane, and recorded as
3614 Here is another point of no return - if the
3615 conflicting package's removal fails we do not unwind
3616 the rest of the installation; the conflicting package
3617 is left in a half-removed limbo.
3622 If there was a conflicting package we go and do the
3623 removal actions (described below), starting with the
3624 removal of the conflicting package's files (any that
3625 are also in the package being installed have already
3626 been removed from the conflicting package's file list,
3627 and so do not get removed now).
3633 <sect id="configdetails"><heading>Details of configuration</heading>
3636 When we configure a package (this happens with <tt>dpkg
3637 --install</tt> and <tt>dpkg --configure</tt>), we first
3638 update any <tt>conffile</tt>s and then call:
3639 <example compact="compact">
3640 <var>postinst</var> configure <var>most-recently-configured-version</var>
3645 No attempt is made to unwind after errors during
3650 If there is no most recently configured version
3651 <prgn>dpkg</prgn> will pass a null argument; older versions
3652 of dpkg may pass <tt><unknown></tt> (including the
3653 angle brackets) in this case. Even older ones do not pass a
3654 second argument at all, under any circumstances.
3658 <sect id="removedetails"><heading>Details of removal and/or
3659 configuration purging</heading>
3664 <example compact="compact">
3665 <var>prerm</var> remove
3669 The package's files are removed (except <tt>conffile</tt>s).
3672 <example compact="compact">
3673 <var>postrm</var> remove
3678 All the maintainer scripts except the <prgn>postrm</prgn>
3683 If we aren't purging the package we stop here. Note
3684 that packages which have no <prgn>postrm</prgn> and no
3685 <tt>conffile</tt>s are automatically purged when
3686 removed, as there is no difference except for the
3687 <prgn>dpkg</prgn> status.
3691 The <tt>conffile</tt>s and any backup files
3692 (<tt>~</tt>-files, <tt>#*#</tt> files,
3693 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
3697 <example compact="compact">
3698 <var>postrm</var> purge
3702 The package's file list is removed.
3706 If there are problems during this process, we call
3707 <example compact="compact">postinst
3708 abort-remove</example>. No other attempt is made to unwind
3709 after errors during removal.
3715 <chapt id="relationships">
3716 <heading>Declaring relationships between packages</heading>
3718 <sect id="depsyntax">
3719 <heading>Syntax of relationship fields</heading>
3722 These fields all have a uniform syntax. They are a list of
3723 package names separated by commas.
3727 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3728 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3729 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3730 control file fields of the package, which declare
3731 dependencies on other packages, the package names listed may
3732 also include lists of alternative package names, separated
3733 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
3734 if any one of the alternative packages is installed, that
3735 part of the dependency is considered to be satisfied.
3739 All of the fields except for <tt>Provides</tt> may restrict
3740 their applicability to particular versions of each named
3741 package. This is done in parentheses after each individual
3742 package name; the parentheses should contain a relation from
3743 the list below followed by a version number, in the format
3744 described in <ref id="f-Version">.
3748 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3749 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3750 strictly earlier, earlier or equal, exactly equal, later or
3751 equal and strictly later, respectively. The deprecated
3752 forms <tt><</tt> and <tt>></tt> were used to mean
3753 earlier/later or equal, rather than strictly earlier/later,
3754 so they should not appear in new packages (though
3755 <prgn>dpkg</prgn> still supports them).
3759 Whitespace may appear at any point in the version
3760 specification subject to the rules in <ref
3761 id="controlsyntax">, and must appear where it's necessary to
3762 disambiguate; it is not otherwise significant. For
3763 consistency and in case of future changes to
3764 <prgn>dpkg</prgn> it is recommended that a single space be
3765 used after a version relationship and before a version
3766 number; it is also conventional to put a single space after
3767 each comma, on either side of each vertical bar, and before
3768 each open parenthesis.
3772 For example, a list of dependencies might appear as:
3773 <example compact="compact">
3776 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
3781 All fields that specify build-time relationships
3782 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3783 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3784 may be restricted to a certain set of architectures. This
3785 is indicated in brackets after each individual package name and
3786 the optional version specification. The brackets enclose a
3787 list of Debian architecture names separated by whitespace.
3788 Exclamation marks may be prepended to each of the names.
3789 (It is not permitted for some names to be prepended with
3790 exclamation marks and others not.) If the current Debian
3791 host architecture is not in this list and there are no
3792 exclamation marks in the list, or it is in the list with a
3793 prepended exclamation mark, the package name and the
3794 associated version specification are ignored completely for
3795 the purposes of defining the relationships.
3800 <example compact="compact">
3802 Build-Depends-Indep: texinfo
3803 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3804 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3809 Note that the binary package relationship fields such as
3810 <tt>Depends</tt> appear in one of the binary package
3811 sections of the control file, whereas the build-time
3812 relationships such as <tt>Build-Depends</tt> appear in the
3813 source package section of the control file (which is the
3818 <sect id="binarydeps">
3819 <heading>Binary Dependencies - <tt>Depends</tt>,
3820 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3821 <tt>Pre-Depends</tt>
3825 Packages can declare in their control file that they have
3826 certain relationships to other packages - for example, that
3827 they may not be installed at the same time as certain other
3828 packages, and/or that they depend on the presence of others.
3832 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
3833 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt> and
3834 <tt>Conflicts</tt> control file fields.
3838 These six fields are used to declare a dependency
3839 relationship by one package on another. Except for
3840 <tt>Enhances</tt>, they appear in the depending (binary)
3841 package's control file. (<tt>Enhances</tt> appears in the
3842 recommending package's control file.)
3846 A <tt>Depends</tt> field takes effect <em>only</em> when a
3847 package is to be configured. It does not prevent a package
3848 being on the system in an unconfigured state while its
3849 dependencies are unsatisfied, and it is possible to replace
3850 a package whose dependencies are satisfied and which is
3851 properly installed with a different version whose
3852 dependencies are not and cannot be satisfied; when this is
3853 done the depending package will be left unconfigured (since
3854 attempts to configure it will give errors) and will not
3855 function properly. If it is necessary, a
3856 <tt>Pre-Depends</tt> field can be used, which has a partial
3857 effect even when a package is being unpacked, as explained
3858 in detail below. (The other three dependency fields,
3859 <tt>Recommends</tt>, <tt>Suggests</tt> and
3860 <tt>Enhances</tt>, are only used by the various front-ends
3861 to <prgn>dpkg</prgn> such as <prgn>dselect</prgn>.)
3865 For this reason packages in an installation run are usually
3866 all unpacked first and all configured later; this gives
3867 later versions of packages with dependencies on later
3868 versions of other packages the opportunity to have their
3869 dependencies satisfied.
3873 The <tt>Depends</tt> field thus allows package maintainers
3874 to impose an order in which packages should be configured.
3878 The meaning of the five dependency fields is as follows:
3880 <tag><tt>Depends</tt></tag>
3883 This declares an absolute dependency. A package will
3884 not be configured unless all of the packages listed in
3885 its <tt>Depends</tt> field have been correctly
3890 The <tt>Depends</tt> field should be used if the
3891 depended-on package is required for the depending
3892 package to provide a significant amount of
3897 The <tt>Depends</tt> field should also be used if the
3898 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
3899 <prgn>postrm</prgn> scripts require the package to be
3900 present in order to run. Note, however, that the
3901 <prgn>postrm</prgn> cannot rely on any non-essential
3902 packages to be present during the <tt>purge</tt>
3906 <tag><tt>Recommends</tt></tag>
3909 This declares a strong, but not absolute, dependency.
3913 The <tt>Recommends</tt> field should list packages
3914 that would be found together with this one in all but
3915 unusual installations.
3919 <tag><tt>Suggests</tt></tag>
3921 This is used to declare that one package may be more
3922 useful with one or more others. Using this field
3923 tells the packaging system and the user that the
3924 listed packages are related to this one and can
3925 perhaps enhance its usefulness, but that installing
3926 this one without them is perfectly reasonable.
3929 <tag><tt>Enhances</tt></tag>
3931 This field is similar to Suggests but works in the
3932 opposite direction. It is used to declare that a
3933 package can enhance the functionality of another
3937 <tag><tt>Pre-Depends</tt></tag>
3940 This field is like <tt>Depends</tt>, except that it
3941 also forces <prgn>dpkg</prgn> to complete installation
3942 of the packages named before even starting the
3943 installation of the package which declares the
3944 pre-dependency, as follows:
3948 When a package declaring a pre-dependency is about to
3949 be <em>unpacked</em> the pre-dependency can be
3950 satisfied if the depended-on package is either fully
3951 configured, <em>or even if</em> the depended-on
3952 package(s) are only unpacked or half-configured,
3953 provided that they have been configured correctly at
3954 some point in the past (and not removed or partially
3955 removed since). In this case, both the
3956 previously-configured and currently unpacked or
3957 half-configured versions must satisfy any version
3958 clause in the <tt>Pre-Depends</tt> field.
3962 When the package declaring a pre-dependency is about
3963 to be <em>configured</em>, the pre-dependency will be
3964 treated as a normal <tt>Depends</tt>, that is, it will
3965 be considered satisfied only if the depended-on
3966 package has been correctly configured.
3970 <tt>Pre-Depends</tt> should be used sparingly,
3971 preferably only by packages whose premature upgrade or
3972 installation would hamper the ability of the system to
3973 continue with any upgrade that might be in progress.
3977 <tt>Pre-Depends</tt> are also required if the
3978 <prgn>preinst</prgn> script depends on the named
3979 package. It is best to avoid this situation if
3987 When selecting which level of dependency to use you should
3988 consider how important the depended-on package is to the
3989 functionality of the one declaring the dependency. Some
3990 packages are composed of components of varying degrees of
3991 importance. Such a package should list using
3992 <tt>Depends</tt> the package(s) which are required by the
3993 more important components. The other components'
3994 requirements may be mentioned as Suggestions or
3995 Recommendations, as appropriate to the components' relative
4000 <sect id="conflicts">
4001 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4004 When one binary package declares a conflict with another
4005 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4006 refuse to allow them to be installed on the system at the
4011 If one package is to be installed, the other must be removed
4012 first - if the package being installed is marked as
4013 replacing (see <ref id="replaces">) the one on the system,
4014 or the one on the system is marked as deselected, or both
4015 packages are marked <tt>Essential</tt>, then
4016 <prgn>dpkg</prgn> will automatically remove the package
4017 which is causing the conflict, otherwise it will halt the
4018 installation of the new package with an error. This
4019 mechanism is specifically designed to produce an error when
4020 the installed package is <tt>Essential</tt>, but the new
4025 A package will not cause a conflict merely because its
4026 configuration files are still installed; it must be at least
4031 A special exception is made for packages which declare a
4032 conflict with their own package name, or with a virtual
4033 package which they provide (see below): this does not
4034 prevent their installation, and allows a package to conflict
4035 with others providing a replacement for it. You use this
4036 feature when you want the package in question to be the only
4037 package providing some feature.
4041 A <tt>Conflicts</tt> entry should almost never have an
4042 "earlier than" version clause. This would prevent
4043 <prgn>dpkg</prgn> from upgrading or installing the package
4044 which declared such a conflict until the upgrade or removal
4045 of the conflicted-with package had been completed.
4049 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4053 As well as the names of actual ("concrete") packages, the
4054 package relationship fields <tt>Depends</tt>,
4055 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4056 <tt>Pre-Depends</tt>, <tt>Conflicts</tt>,
4057 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4058 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4059 may mention "virtual packages".
4063 A <em>virtual package</em> is one which appears in the
4064 <tt>Provides</tt> control file field of another package.
4065 The effect is as if the package(s) which provide a
4066 particular virtual package name had been listed by name
4067 everywhere the virtual package name appears. (See also <ref
4072 If there are both concrete and virtual packages of the same
4073 name, then the dependency may be satisfied (or the conflict
4074 caused) by either the concrete package with the name in
4075 question or any other concrete package which provides the
4076 virtual package with the name in question. This is so that,
4077 for example, supposing we have
4078 <example compact="compact">
4082 and someone else releases an enhanced version of the
4083 <tt>bar</tt> package (for example, a non-US variant), they
4085 <example compact="compact">
4089 and the <tt>bar-plus</tt> package will now also satisfy the
4090 dependency for the <tt>foo</tt> package.
4094 If a dependency or a conflict has a version number attached
4095 then only real packages will be considered to see whether
4096 the relationship is satisfied (or the prohibition violated,
4097 for a conflict) - it is assumed that a real package which
4098 provides the virtual package is not of the "right" version.
4099 So, a <tt>Provides</tt> field may not contain version
4100 numbers, and the version number of the concrete package
4101 which provides a particular virtual package will not be
4102 looked at when considering a dependency on or conflict with
4103 the virtual package name.
4107 It is likely that the ability will be added in a future
4108 release of <prgn>dpkg</prgn> to specify a version number for
4109 each virtual package it provides. This feature is not yet
4110 present, however, and is expected to be used only
4115 If you want to specify which of a set of real packages
4116 should be the default to satisfy a particular dependency on
4117 a virtual package, you should list the real package as an
4118 alternative before the virtual one.
4123 <sect id="replaces"><heading>Overwriting files and replacing
4124 packages - <tt>Replaces</tt></heading>
4127 Packages can declare in their control file that they should
4128 overwrite files in certain other packages, or completely
4129 replace other packages. The <tt>Replaces</tt> control file
4130 field has these two distinct purposes.
4133 <sect1><heading>Overwriting files in other packages</heading>
4136 Firstly, as mentioned before, it is usually an error for a
4137 package to contain files which are on the system in
4142 However, if the overwriting package declares that it
4143 <tt>Replaces</tt> the one containing the file being
4144 overwritten, then <prgn>dpkg</prgn> will replace the file
4145 from the old package with that from the new. The file
4146 will no longer be listed as "owned" by the old package.
4150 If a package is completely replaced in this way, so that
4151 <prgn>dpkg</prgn> does not know of any files it still
4152 contains, it is considered to have "disappeared". It will
4153 be marked as not wanted on the system (selected for
4154 removal) and not installed. Any <tt>conffile</tt>s
4155 details noted for the package will be ignored, as they
4156 will have been taken over by the overwriting package. The
4157 package's <prgn>postrm</prgn> script will be run with a
4158 special argument to allow the package to do any final
4159 cleanup required. See <ref id="mscriptsinstact">.
4162 Replaces is a one way relationship -- you have to
4163 install the replacing package after the replaced
4170 For this usage of <tt>Replaces</tt>, virtual packages (see
4171 <ref id="virtual">) are not considered when looking at a
4172 <tt>Replaces</tt> field - the packages declared as being
4173 replaced must be mentioned by their real names.
4177 Furthermore, this usage of <tt>Replaces</tt> only takes
4178 effect when both packages are at least partially on the
4179 system at once, so that it can only happen if they do not
4180 conflict or if the conflict has been overridden.
4185 <sect1><heading>Replacing whole packages, forcing their
4189 Secondly, <tt>Replaces</tt> allows the packaging system to
4190 resolve which package should be removed when there is a
4191 conflict - see <ref id="conflicts">. This usage only
4192 takes effect when the two packages <em>do</em> conflict,
4193 so that the two usages of this field do not interfere with
4198 In this situation, the package declared as being replaced
4199 can be a virtual package, so for example, all mail
4200 transport agents (MTAs) would have the following fields in
4201 their control files:
4202 <example compact="compact">
4203 Provides: mail-transport-agent
4204 Conflicts: mail-transport-agent
4205 Replaces: mail-transport-agent
4207 ensuring that only one MTA can be installed at any one
4212 <sect id="sourcebinarydeps">
4213 <heading>Relationships between source and binary packages -
4214 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4215 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4219 Source packages that require certain binary packages to be
4220 installed or absent at the time of building the package
4221 can declare relationships to those binary packages.
4225 This is done using the <tt>Build-Depends</tt>,
4226 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4227 <tt>Build-Conflicts-Indep</tt> control file fields.
4231 Build-dependencies on "build-essential" binary packages can be
4232 omitted. Please see <ref id="pkg-relations"> for more information.
4236 The dependencies and conflicts they define must be satisfied
4237 (as defined earlier for binary packages) in order to invoke
4238 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4240 If you make "build-arch" or "binary-arch", you need
4241 Build-Depends. If you make "build-indep" or
4242 "binary-indep", you need Build-Depends and
4243 Build-Depends-Indep. If you make "build" or "binary",
4247 There is no Build-Depends-Arch; the autobuilders will
4248 only need the Build-Depends if they know how to build
4249 only build-arch and binary-arch. Anyone building the
4250 build-indep/binary-indep targets is basically assumed to
4251 be building the whole package and so installs all build
4255 The purpose of the original split, I recall, was so that
4256 the autobuilders wouldn't need to install extra packages
4257 needed only for the binary-indep targets. But without a
4258 build-arch/build-indep split, this didn't work, since
4259 most of the work is done in the build target, not in the
4265 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4267 The <tt>Build-Depends</tt> and
4268 <tt>Build-Conflicts</tt> fields must be satisfied when
4269 any of the following targets is invoked:
4270 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4271 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4272 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4274 <tag><tt>Build-Depends-Indep</tt>,
4275 <tt>Build-Conflicts-Indep</tt></tag>
4277 The <tt>Build-Depends-Indep</tt> and
4278 <tt>Build-Conflicts-Indep</tt> fields must be
4279 satisfied when any of the following targets is
4280 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4281 <tt>binary</tt> and <tt>binary-indep</tt>.
4291 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4294 Packages containing shared libraries must be constructed with
4295 a little care to make sure that the shared library is always
4296 available. This is especially important for packages whose
4297 shared libraries are vitally important, such as the C library
4298 (currently <tt>libc6</tt>).
4302 Packages involving shared libraries should be split up into
4303 several binary packages. This section mostly deals with how
4304 this separation is to be accomplished; rules for files within
4305 the shared library packages are in <ref id="libraries"> instead.
4308 <sect id="sharedlibs-runtime">
4309 <heading>Run-time shared libraries</heading>
4312 The run-time shared library needs to be placed in a package called
4313 <package><var>libraryname</var><var>soversion</var></package>, where
4314 <file><var>soversion</var></file> is the version number in the
4315 soname of the shared library<footnote>
4316 The soname is the shared object name: it's the thing
4317 that has to match exactly between building an executable
4318 and running it for the dynamic linker to be able run the
4319 program. For example, if the soname of the library is
4320 <file>libfoo.so.6</file>, the library package would be
4321 called <file>libfoo6</file>.
4323 Alternatively, if it would be confusing to directly append
4324 <var>soversion</var> to <var>libraryname</var> (e.g. because
4325 <var>libraryname</var> itself ends in a number), you may use
4326 <package><var>libraryname</var>-<var>soversion</var></package> and
4327 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4332 If you have several shared libraries built from the same
4333 source tree you may lump them all together into a single
4334 shared library package, provided that you change all of
4335 their sonames at once (so that you don't get filename
4336 clashes if you try to install different versions of the
4337 combined shared libraries package).
4341 The package should install the shared libraries under
4342 their normal names. For example, the <package>libgdbm3</package>
4343 package should install <file>libgdbm.so.3.0.0</file> as
4344 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4345 renamed or re-linked by any <prgn>prerm</prgn> or
4346 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4347 of renaming things safely without affecting running programs,
4348 and attempts to interfere with this are likely to lead to
4353 Shared libraries should not be installed executable, since
4354 the dynamic linker does not require this and trying to
4355 execute a shared library usually results in a core dump.
4359 The run-time library package should include the symbolic link that
4360 <prgn>ldconfig</prgn> would create for the shared libraries.
4361 For example, the <package>libgdbm3</package> package should include
4362 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4363 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4364 linker (for example <prgn>ld.so</prgn> or
4365 <prgn>ld-linux.so.*</prgn>) can find the library between the
4366 time that <prgn>dpkg</prgn> installs it and the time that
4367 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4369 The package management system requires the library to be
4370 placed before the symbolic link pointing to it in the
4371 <file>.deb</file> file. This is so that when
4372 <prgn>dpkg</prgn> comes to install the symlink
4373 (overwriting the previous symlink pointing at an older
4374 version of the library), the new shared library is already
4375 in place. In the past, this was achieved by creating the
4376 library in the temporary packaging directory before
4377 creating the symlink. Unfortunately, this was not always
4378 effective, since the building of the tar file in the
4379 <file>.deb</file> depended on the behavior of the underlying
4380 file system. Some file systems (such as reiserfs) reorder
4381 the files so that the order of creation is forgotten.
4382 Since version 1.7.0, <prgn>dpkg</prgn>
4383 reorders the files itself as necessary when building a
4384 package. Thus it is no longer important to concern
4385 oneself with the order of file creation.
4389 <sect1 id="ldconfig">
4390 <heading><tt>ldconfig</tt></heading>
4393 Any package installing shared libraries in one of the default
4394 library directories of the dynamic linker (which are currently
4395 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4396 listed in <file>/etc/ld.so.conf</file><footnote>
4398 <list compact="compact">
4399 <item>/usr/X11R6/lib/Xaw3d</item>
4400 <item>/usr/local/lib</item>
4401 <item>/usr/lib/libc5-compat</item>
4402 <item>/lib/libc5-compat</item>
4403 <item>/usr/X11R6/lib</item>
4406 must use <prgn>ldconfig</prgn> to update the shared library
4411 The package must call <prgn>ldconfig</prgn> in the
4412 <prgn>postinst</prgn> script if the first argument is
4413 <tt>configure</tt>; the <prgn>postinst</prgn> script may
4414 optionally invoke <prgn>ldconfig</prgn> at other times. The
4415 package should call <prgn>ldconfig</prgn> in the
4416 <prgn>postrm</prgn> script if the first argument is
4417 <tt>remove</tt>. The maintainer scripts must not invoke
4418 <prgn>ldconfig</prgn> under any circumstances other than those
4419 described in this paragraph.<footnote>
4421 During install or upgrade, the preinst is called before
4422 the new files are installed, so calling "ldconfig" is
4423 pointless. The preinst of an existing package can also be
4424 called if an upgrade fails. However, this happens during
4425 the critical time when a shared libs may exist on-disk
4426 under a temporary name. Thus, it is dangerous and
4427 forbidden by current policy to call "ldconfig" at this
4432 When a package is installed or upgraded, "postinst
4433 configure" runs after the new files are safely on-disk.
4434 Since it is perfectly safe to invoke ldconfig
4435 unconditionally in a postinst, it is OK for a package to
4436 simply put ldconfig in its postinst without checking the
4437 argument. The postinst can also be called to recover from
4438 a failed upgrade. This happens before any new files are
4439 unpacked, so there is no reason to call "ldconfig" at this
4444 For a package that is being removed, prerm is
4445 called with all the files intact, so calling ldconfig is
4446 useless. The other calls to "prerm" happen in the case of
4447 upgrade at a time when all the files of the old package
4448 are on-disk, so again calling "ldconfig" is pointless.
4452 postrm, on the other hand, is called with the "remove"
4453 argument just after the files are removed, so this is the
4454 proper time to call "ldconfig" to notify the system of the
4455 fact shared libraries from the package are removed.
4456 The postrm can be called at several other times. At the
4457 time of "postrm purge", "postrm abort-install", or "postrm
4458 abort-upgrade", calling "ldconfig" is useless because the
4459 shared lib files are not on-disk. However, when "postrm"
4460 is invoked with arguments "upgrade", "failed-upgrade", or
4461 "disappear", a shared lib may exist on-disk under a
4470 <sect id="sharedlibs-runtime-progs">
4471 <heading>Run-time support programs</heading>
4474 If your package has some run-time support programs which use
4475 the shared library you must not put them in the shared
4476 library package. If you do that then you won't be able to
4477 install several versions of the shared library without
4478 getting filename clashes.
4482 Instead, either create another package for the runtime binaries
4483 (this package might typically be named
4484 <package><var>libraryname</var>-runtime</package>; note the absence
4485 of the <var>soversion</var> in the package name), or if the
4486 development package is small, include them in there.
4490 <sect id="sharedlibs-static">
4491 <heading>Static libraries</heading>
4494 The static library (<file><var>libraryname.a</var></file>)
4495 is usually provided in addition to the shared version.
4496 It is placed into the development package (see below).
4500 In some cases, it is acceptable for a library to be
4501 available in static form only; these cases include:
4503 <item>libraries for languages whose shared library support
4504 is immature or unstable</item>
4505 <item>libraries whose interfaces are in flux or under
4506 development (commonly the case when the library's
4507 major version number is zero, or where the ABI breaks
4508 across patchlevels)</item>
4509 <item>libraries which are explicitly intended to be
4510 available only in static form by their upstream
4515 <sect id="sharedlibs-dev">
4516 <heading>Development files</heading>
4519 The development files associated to a shared library need to be
4520 placed in a package called
4521 <package><var>libraryname</var><var>soversion</var>-dev</package>,
4522 or if you prefer only to support one development version at a
4523 time, <package><var>libraryname</var>-dev</package>.
4527 In case several development versions of a library exist, you may
4528 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
4529 <ref id="conflicts">) to ensure that the user only installs one
4530 development version at a time (as different development versions are
4531 likely to have the same header files in them, which would cause a
4532 filename clash if both were installed).
4536 The development package should contain a symlink for the associated
4537 shared library without a version number. For example, the
4538 <package>libgdbm-dev</package> package should include a symlink
4539 from <file>/usr/lib/libgdbm.so</file> to
4540 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
4541 (<prgn>ld</prgn>) when compiling packages, as it will only look for
4542 <file>libgdbm.so</file> when compiling dynamically.
4546 <sect id="sharedlibs-intradeps">
4547 <heading>Dependencies between the packages of the same library</heading>
4550 Typically the development version should have an exact
4551 version dependency on the runtime library, to make sure that
4552 compilation and linking happens correctly. The
4553 <tt>${Source-Version}</tt> substitution variable can be
4554 useful for this purpose.
4558 <sect id="sharedlibs-shlibdeps">
4559 <heading>Dependencies between the library and other packages -
4560 the <tt>shlibs</tt> system</heading>
4563 If a package contains a binary or library which links to a
4564 shared library, we must ensure that when the package is
4565 installed on the system, all of the libraries needed are
4566 also installed. This requirement led to the creation of the
4567 <tt>shlibs</tt> system, which is very simple in its design:
4568 any package which <em>provides</em> a shared library also
4569 provides information on the package dependencies required to
4570 ensure the presence of this library, and any package which
4571 <em>uses</em> a shared library uses this information to
4572 determine the dependencies it requires. The files which
4573 contain the mapping from shared libraries to the necessary
4574 dependency information are called <file>shlibs</file> files.
4578 Thus, when a package is built which contains any shared
4579 libraries, it must provide a <file>shlibs</file> file for other
4580 packages to use, and when a package is built which contains
4581 any shared libraries or compiled binaries, it must run
4582 <prgn>dpkg-shlibdeps</prgn> on these to determine the
4583 libraries used and hence the dependencies needed by this
4586 In the past, the shared libraries linked to were
4587 determined by calling <prgn>ldd</prgn>, but now
4588 <prgn>objdump</prgn> is used to do this. The only
4589 change this makes to package building is that
4590 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
4591 libraries, whereas in the past this was unnecessary.
4592 The rest of this footnote explains the advantage that
4597 We say that a binary <tt>foo</tt> <em>directly</em> uses
4598 a library <tt>libbar</tt> if it is explicitly linked
4599 with that library (that is, it uses the flag
4600 <tt>-lbar</tt> during the linking stage). Other
4601 libraries that are needed by <tt>libbar</tt> are linked
4602 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
4603 linker will load them automatically when it loads
4604 <tt>libbar</tt>. A package should depend on
4605 the libraries it directly uses, and the dependencies for
4606 those libraries should automatically pull in the other
4611 Unfortunately, the <prgn>ldd</prgn> program shows both
4612 the directly and indirectly used libraries, meaning that
4613 the dependencies determined included both direct and
4614 indirect dependencies. The use of <prgn>objdump</prgn>
4615 avoids this problem by determining only the directly
4620 A good example of where this helps is the following. We
4621 could update <tt>libimlib</tt> with a new version that
4622 supports a new graphics format called dgf (but retaining
4623 the same major version number). If we used the old
4624 <prgn>ldd</prgn> method, every package that uses
4625 <tt>libimlib</tt> would need to be recompiled so it
4626 would also depend on <tt>libdgf</tt> or it wouldn't run
4627 due to missing symbols. However with the new system,
4628 packages using <tt>libimlib</tt> can rely on
4629 <tt>libimlib</tt> itself having the dependency on
4630 <tt>libdgf</tt> and so they would not need rebuilding.
4636 In the following sections, we will first describe where the
4637 various <tt>shlibs</tt> files are to be found, then how to
4638 use <prgn>dpkg-shlibdeps</prgn>, and finally the
4639 <tt>shlibs</tt> file format and how to create them if your
4640 package contains a shared library.
4644 <heading>The <tt>shlibs</tt> files present on the system</heading>
4647 There are several places where <tt>shlibs</tt> files are
4648 found. The following list gives them in the order in which
4649 they are read by <prgn>dpkg-shlibdeps</prgn>. (The first
4650 one which gives the required information is used.)
4656 <p><file>debian/shlibs.local</file></p>
4659 This lists overrides for this package. Its use is
4660 described below (see <ref id="shlibslocal">).
4665 <p><file>/etc/dpkg/shlibs.override</file></p>
4668 This lists global overrides. This list is normally
4669 empty. It is maintained by the local system
4675 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
4678 When packages are being built, any
4679 <file>debian/shlibs</file> files are copied into the
4680 control file area of the temporary build directory and
4681 given the name <file>shlibs</file>. These files give
4682 details of any shared libraries included in the
4684 An example may help here. Let us say that the
4685 source package <tt>foo</tt> generates two binary
4686 packages, <tt>libfoo2</tt> and
4687 <tt>foo-runtime</tt>. When building the binary
4688 packages, the two packages are created in the
4689 directories <file>debian/libfoo2</file> and
4690 <file>debian/foo-runtime</file> respectively.
4691 (<file>debian/tmp</file> could be used instead of one
4692 of these.) Since <tt>libfoo2</tt> provides the
4693 <tt>libfoo</tt> shared library, it will require a
4694 <tt>shlibs</tt> file, which will be installed in
4695 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
4697 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
4698 when <prgn>dpkg-shlibdeps</prgn> is run on the
4700 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
4702 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
4703 determine whether <tt>foo-prog</tt>'s library
4704 dependencies are satisfied by any of the libraries
4705 provided by <tt>libfoo2</tt>. For this reason,
4706 <prgn>dpkg-shlibdeps</prgn> must only be run once
4707 all of the individual binary packages'
4708 <tt>shlibs</tt> files have been installed into the
4715 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
4718 These are the <file>shlibs</file> files corresponding to
4719 all of the packages installed on the system, and are
4720 maintained by the relevant package maintainers.
4725 <p><file>/etc/dpkg/shlibs.default</file></p>
4728 This file lists any shared libraries whose packages
4729 have failed to provide correct <file>shlibs</file> files.
4730 It was used when the <file>shlibs</file> setup was first
4731 introduced, but it is now normally empty. It is
4732 maintained by the <tt>dpkg</tt> maintainer.
4740 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
4741 <file>shlibs</file> files</heading>
4744 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
4745 <file>debian/rules</file> file. If your package contains only
4746 compiled binaries and libraries (but no scripts), you can
4747 use a command such as:
4748 <example compact="compact">
4749 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
4750 debian/tmp/usr/lib/*
4752 Otherwise, you will need to explicitly list the compiled
4753 binaries and libraries.<footnote>
4754 If you are using <tt>debhelper</tt>, the
4755 <prgn>dh_shlibdeps</prgn> program will do this work for
4756 you. It will also correctly handle multi-binary
4762 This command puts the dependency information into the
4763 <file>debian/substvars</file> file, which is then used by
4764 <prgn>dpkg-gencontrol</prgn>. You will need to place a
4765 <tt>${shlib:Depends}</tt> variable in the <tt>Depends</tt>
4766 field in the control file for this to work.
4770 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
4771 done. If it does complain you might need to create your own
4772 <file>debian/shlibs.local</file> file, as explained below (see
4773 <ref id="shlibslocal">).
4777 If you have multiple binary packages, you will need to call
4778 <prgn>dpkg-shlibdeps</prgn> on each one which contains
4779 compiled libraries or binaries. In such a case, you will
4780 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
4781 utilities to specify a different <file>substvars</file> file.
4782 For more details on this and other options, see <manref
4783 name="dpkg-shlibdeps" section="1">.
4788 <heading>The <file>shlibs</file> File Format</heading>
4791 Each <file>shlibs</file> file has the same format. Lines
4792 beginning with <tt>#</tt> are considered to be comments and
4793 are ignored. Each line is of the form:
4794 <example compact="compact">
4795 <var>library-name</var> <var>soname-version-number</var> <var>dependencies ...</var>
4800 We will explain this by reference to the example of the
4801 <tt>zlib1g</tt> package, which (at the time of writing)
4802 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
4806 <var>library-name</var> is the name of the shared library,
4807 in this case <tt>libz</tt>. (This must match the name part
4808 of the soname, see below.)
4812 <var>soname-version-number</var> is the version part of the
4813 soname of the library. The soname is the thing that must
4814 exactly match for the library to be recognized by the
4815 dynamic linker, and is usually of the form
4816 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
4817 example, <tt>libz.so.1</tt>.<footnote>
4818 This can be determined using the command
4819 <example compact="compact">
4820 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
4823 The version part is the part which comes after
4824 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
4828 <var>dependencies</var> has the same syntax as a dependency
4829 field in a binary package control file. It should give
4830 details of which packages are required to satisfy a binary
4831 built against the version of the library contained in the
4832 package. See <ref id="depsyntax"> for details.
4836 In our example, if the first version of the <tt>zlib1g</tt>
4837 package which contained a minor number of at least
4838 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
4839 <tt>shlibs</tt> entry for this library could say:
4840 <example compact="compact">
4841 libz 1 zlib1g (>= 1:1.1.3)
4843 The version-specific dependency is to avoid warnings from
4844 the dynamic linker about using older shared libraries with
4850 <heading>Providing a <file>shlibs</file> file</heading>
4853 If your package provides a shared library, you should create
4854 a <file>shlibs</file> file following the format described above.
4855 It is usual to call this file <file>debian/shlibs</file> (but if
4856 you have multiple binary packages, you might want to call it
4857 <file>debian/shlibs.<var>package</var></file> instead). Then
4858 let <file>debian/rules</file> install it in the control area:
4859 <example compact="compact">
4860 install -m644 debian/shlibs debian/tmp/DEBIAN
4862 or, in the case of a multi-binary package:
4863 <example compact="compact">
4864 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
4866 An alternative way of doing this is to create the
4867 <file>shlibs</file> file in the control area directly from
4868 <file>debian/rules</file> without using a <file>debian/shlibs</file>
4869 file at all,<footnote>
4870 This is what <prgn>dh_makeshlibs</prgn> in the
4871 <tt>debhelper</tt> suite does.
4873 since the <file>debian/shlibs</file> file itself is ignored by
4874 <prgn>dpkg-shlibdeps</prgn>.
4878 As <prgn>dpkg-shlibdeps</prgn> reads the
4879 <file>DEBIAN/shlibs</file> files in all of the binary packages
4880 being built from this source package, all of the
4881 <file>DEBIAN/shlibs</file> files should be installed before
4882 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
4887 <sect1 id="shlibslocal">
4888 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
4891 This file is intended only as a <em>temporary</em> fix if
4892 your binaries or libraries depend on a library whose package
4893 does not yet provide a correct <file>shlibs</file> file.
4897 We will assume that you are trying to package a binary
4898 <tt>foo</tt>. When you try running
4899 <prgn>dpkg-shlibdeps</prgn> you get the following error
4900 message (<tt>-O</tt> displays the dependency information on
4901 <tt>stdout</tt> instead of writing it to
4902 <tt>debian/substvars</tt>, and the lines have been wrapped
4903 for ease of reading):
4904 <example compact="compact">
4905 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
4906 dpkg-shlibdeps: warning: unable to find dependency
4907 information for shared library libbar (soname 1,
4908 path /usr/lib/libbar.so.1, dependency field Depends)
4909 shlibs:Depends=libc6 (>= 2.2.2-2)
4911 You can then run <prgn>ldd</prgn> on the binary to find the
4912 full location of the library concerned:
4913 <example compact="compact">
4915 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
4916 libc.so.6 => /lib/libc.so.6 (0x40032000)
4917 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
4919 So the <prgn>foo</prgn> binary depends on the
4920 <prgn>libbar</prgn> shared library, but no package seems to
4921 provide a <file>*.shlibs</file> file handling
4922 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
4923 determine the package responsible:
4924 <example compact="compact">
4925 $ dpkg -S /usr/lib/libbar.so.1
4926 bar1: /usr/lib/libbar.so.1
4927 $ dpkg -s bar1 | grep Version
4930 This tells us that the <tt>bar1</tt> package, version 1.0-1,
4931 is the one we are using. Now we can file a bug against the
4932 <tt>bar1</tt> package and create our own
4933 <file>debian/shlibs.local</file> to locally fix the problem.
4934 Including the following line into your
4935 <file>debian/shlibs.local</file> file:
4936 <example compact="compact">
4937 libbar 1 bar1 (>= 1.0-1)
4939 should allow the package build to work.
4943 As soon as the maintainer of <tt>bar1</tt> provides a
4944 correct <file>shlibs</file> file, you should remove this line
4945 from your <file>debian/shlibs.local</file> file. (You should
4946 probably also then have a versioned <tt>Build-Depends</tt>
4947 on <tt>bar1</tt> to help ensure that others do not have the
4948 same problem building your package.)
4957 <chapt id="opersys"><heading>The Operating System</heading>
4960 <heading>Filesystem hierarchy</heading>
4964 <heading>Filesystem Structure</heading>
4967 The location of all installed files and directories must
4968 comply with the Filesystem Hierarchy Standard (FHS),
4969 version 2.1, except where doing so would violate other
4970 terms of Debian Policy. The version of this document
4971 referred here can be found in the <tt>debian-policy</tt>
4973 <url id="http://www.debian.org/doc/packaging-manuals/fhs/"
4974 name="FHS (Debian copy)"> alongside this manual (or, if
4975 you have the <package>debian-policy</package> installed,
4977 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
4978 (local copy)">). The
4979 latest version, which may be a more recent version, may
4981 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
4982 Specific questions about following the standard may be
4983 asked on the <tt>debian-devel</tt> mailing list, or
4984 referred to the FHS mailing list (see the
4985 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
4991 <heading>Site-specific programs</heading>
4994 As mandated by the FHS, packages must not place any
4995 files in <file>/usr/local</file>, either by putting them in
4996 the file system archive to be unpacked by <prgn>dpkg</prgn>
4997 or by manipulating them in their maintainer scripts.
5001 However, the package may create empty directories below
5002 <file>/usr/local</file> so that the system administrator knows
5003 where to place site-specific files. These directories
5004 should be removed on package removal if they are
5009 Note, that this applies only to directories <em>below</em>
5010 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
5011 Packages must not create sub-directories in the directory
5012 <file>/usr/local</file> itself, except those listed in FHS,
5013 section 4.5. However, you may create directories below
5014 them as you wish. You must not remove any of the
5015 directories listed in 4.5, even if you created them.
5019 Since <file>/usr/local</file> can be mounted read-only from a
5020 remote server, these directories must be created and
5021 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5022 maintainer scripts and not be included in the
5023 <file>.deb</file> archive. These scripts must not fail if
5024 either of these operations fail.
5028 For example, the <tt>emacsen-common</tt> package could
5029 contain something like
5030 <example compact="compact">
5031 if [ ! -e /usr/local/share/emacs ]
5033 if mkdir /usr/local/share/emacs 2>/dev/null
5035 chown root:staff /usr/local/share/emacs
5036 chmod 2775 /usr/local/share/emacs
5040 in its <prgn>postinst</prgn> script, and
5041 <example compact="compact">
5042 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5043 rmdir /usr/local/share/emacs 2>/dev/null || true
5045 in the <prgn>prerm</prgn> script. (Note that this form is
5046 used to ensure that if the script is interrupted, the
5047 directory <file>/usr/local/share/emacs</file> will still be
5052 If you do create a directory in <file>/usr/local</file> for
5053 local additions to a package, you should ensure that
5054 settings in <file>/usr/local</file> take precedence over the
5055 equivalents in <file>/usr</file>.
5059 However, because <file>/usr/local</file> and its contents are
5060 for exclusive use of the local administrator, a package
5061 must not rely on the presence or absence of files or
5062 directories in <file>/usr/local</file> for normal operation.
5066 The <file>/usr/local</file> directory itself and all the
5067 subdirectories created by the package should (by default) have
5068 permissions 2775 (group-writable and set-group-id) and be
5069 owned by <tt>root.staff</tt>.
5074 <heading>The system-wide mail directory</heading>
5076 The system-wide mail directory is <file>/var/mail</file>. This
5077 directory is part of the base system and should not owned
5078 by any particular mail agents. The use of the old
5079 location <file>/var/spool/mail</file> is deprecated, even
5080 though the spool may still be physically located there.
5081 To maintain partial upgrade compatibility for systems
5082 which have <file>/var/spool/mail</file> as their physical mail
5083 spool, packages using <file>/var/mail</file> must depend on
5084 either <package>libc6</package> (>= 2.1.3-13), or on
5085 <package>base-files</package> (>= 2.2.0), or on later
5086 versions of either one of these packages.
5092 <heading>Users and groups</heading>
5095 <heading>Introduction</heading>
5097 The Debian system can be configured to use either plain or
5102 Some user ids (UIDs) and group ids (GIDs) are reserved
5103 globally for use by certain packages. Because some
5104 packages need to include files which are owned by these
5105 users or groups, or need the ids compiled into binaries,
5106 these ids must be used on any Debian system only for the
5107 purpose for which they are allocated. This is a serious
5108 restriction, and we should avoid getting in the way of
5109 local administration policies. In particular, many sites
5110 allocate users and/or local system groups starting at 100.
5114 Apart from this we should have dynamically allocated ids,
5115 which should by default be arranged in some sensible
5116 order, but the behavior should be configurable.
5120 Packages other than <tt>base-passwd</tt> must not modify
5121 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5122 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5127 <heading>UID and GID classes</heading>
5129 The UID and GID numbers are divided into classes as
5135 Globally allocated by the Debian project, the same
5136 on every Debian system. These ids will appear in
5137 the <file>passwd</file> and <file>group</file> files of all
5138 Debian systems, new ids in this range being added
5139 automatically as the <tt>base-passwd</tt> package is
5144 Packages which need a single statically allocated
5145 uid or gid should use one of these; their
5146 maintainers should ask the <tt>base-passwd</tt>
5154 Dynamically allocated system users and groups.
5155 Packages which need a user or group, but can have
5156 this user or group allocated dynamically and
5157 differently on each system, should use <tt>adduser
5158 --system</tt> to create the group and/or user.
5159 <prgn>adduser</prgn> will check for the existence of
5160 the user or group, and if necessary choose an unused
5161 id based on the ranges specified in
5162 <file>adduser.conf</file>.
5166 <tag>1000-29999:</tag>
5169 Dynamically allocated user accounts. By default
5170 <prgn>adduser</prgn> will choose UIDs and GIDs for
5171 user accounts in this range, though
5172 <file>adduser.conf</file> may be used to modify this
5177 <tag>30000-59999:</tag>
5182 <tag>60000-64999:</tag>
5185 Globally allocated by the Debian project, but only
5186 created on demand. The ids are allocated centrally
5187 and statically, but the actual accounts are only
5188 created on users' systems on demand.
5192 These ids are for packages which are obscure or
5193 which require many statically-allocated ids. These
5194 packages should check for and create the accounts in
5195 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5196 <prgn>adduser</prgn> if it has this facility) if
5197 necessary. Packages which are likely to require
5198 further allocations should have a "hole" left after
5199 them in the allocation, to give them room to
5204 <tag>65000-65533:</tag>
5212 User <tt>nobody</tt>. The corresponding gid refers
5213 to the group <tt>nogroup</tt>.
5220 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5221 not</em> be used, because it is the error return
5230 <sect id="sysvinit">
5231 <heading>System run levels and <file>init.d</file> scripts</heading>
5233 <sect1 id="/etc/init.d">
5234 <heading>Introduction</heading>
5237 The <file>/etc/init.d</file> directory contains the scripts
5238 executed by <prgn>init</prgn> at boot time and when the
5239 init state (or "runlevel") is changed (see <manref
5240 name="init" section="8">).
5244 There are at least two different, yet functionally
5245 equivalent, ways of handling these scripts. For the sake
5246 of simplicity, this document describes only the symbolic
5247 link method. However, it must not be assumed by maintainer
5248 scripts that this method is being used, and any automated
5249 manipulation of the various runlevel behaviours by
5250 maintainer scripts must be performed using
5251 <prgn>update-rc.d</prgn> as described below and not by
5252 manually installing or removing symlinks. For information
5253 on the implementation details of the other method,
5254 implemented in the <tt>file-rc</tt> package, please refer
5255 to the documentation of that package.
5259 These scripts are referenced by symbolic links in the
5260 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5261 runlevels, <prgn>init</prgn> looks in the directory
5262 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5263 execute, where <tt><var>n</var></tt> is the runlevel that
5264 is being changed to, or <tt>S</tt> for the boot-up
5269 The names of the links all have the form
5270 <file>S<var>mm</var><var>script</var></file> or
5271 <file>K<var>mm</var><var>script</var></file> where
5272 <var>mm</var> is a two-digit number and <var>script</var>
5273 is the name of the script (this should be the same as the
5274 name of the actual script in <file>/etc/init.d</file>).
5278 When <prgn>init</prgn> changes runlevel first the targets
5279 of the links whose names start with a <tt>K</tt> are
5280 executed, each with the single argument <tt>stop</tt>,
5281 followed by the scripts prefixed with an <tt>S</tt>, each
5282 with the single argument <tt>start</tt>. (The links are
5283 those in the <file>/etc/rc<var>n</var>.d</file> directory
5284 corresponding to the new runlevel.) The <tt>K</tt> links
5285 are responsible for killing services and the <tt>S</tt>
5286 link for starting services upon entering the runlevel.
5290 For example, if we are changing from runlevel 2 to
5291 runlevel 3, init will first execute all of the <tt>K</tt>
5292 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
5293 all of the <tt>S</tt> prefixed scripts in that directory.
5294 The links starting with <tt>K</tt> will cause the
5295 referred-to file to be executed with an argument of
5296 <tt>stop</tt>, and the <tt>S</tt> links with an argument
5301 The two-digit number <var>mm</var> is used to determine
5302 the order in which to run the scripts: low-numbered links
5303 have their scripts run first. For example, the
5304 <tt>K20</tt> scripts will be executed before the
5305 <tt>K30</tt> scripts. This is used when a certain service
5306 must be started before another. For example, the name
5307 server <prgn>bind</prgn> might need to be started before
5308 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
5309 can set up its access lists. In this case, the script
5310 that starts <prgn>bind</prgn> would have a lower number
5311 than the script that starts <prgn>inn</prgn> so that it
5313 <example compact="compact">
5320 The two runlevels 0 (halt) and 6 (reboot) are slightly
5321 different. In these runlevels, the links with an
5322 <tt>S</tt> prefix are still called after those with a
5323 <tt>K</tt> prefix, but they too are called with the single
5324 argument <tt>stop</tt>.
5328 Also, if the script name ends <tt>.sh</tt>, the script
5329 will be sourced in runlevel <tt>S</tt> rather that being
5330 run in a forked subprocess, but will be explicitly run by
5331 <prgn>sh</prgn> in all other runlevels.
5336 <heading>Writing the scripts</heading>
5339 Packages that include daemons for system services should
5340 place scripts in <file>/etc/init.d</file> to start or stop
5341 services at boot time or during a change of runlevel.
5342 These scripts should be named
5343 <file>/etc/init.d/<var>package</var></file>, and they should
5344 accept one argument, saying what to do:
5347 <tag><tt>start</tt></tag>
5348 <item>start the service,</item>
5350 <tag><tt>stop</tt></tag>
5351 <item>stop the service,</item>
5353 <tag><tt>restart</tt></tag>
5354 <item>stop and restart the service if it's already running,
5355 otherwise start the service</item>
5357 <tag><tt>reload</tt></tag>
5358 <item><p>cause the configuration of the service to be
5359 reloaded without actually stopping and restarting
5362 <tag><tt>force-reload</tt></tag>
5363 <item>cause the configuration to be reloaded if the
5364 service supports this, otherwise restart the
5368 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
5369 <tt>force-reload</tt> options should be supported by all
5370 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
5375 The <file>init.d</file> scripts should ensure that they will
5376 behave sensibly if invoked with <tt>start</tt> when the
5377 service is already running, or with <tt>stop</tt> when it
5378 isn't, and that they don't kill unfortunately-named user
5379 processes. The best way to achieve this is usually to use
5380 <prgn>start-stop-daemon</prgn>.
5384 If a service reloads its configuration automatically (as
5385 in the case of <prgn>cron</prgn>, for example), the
5386 <tt>reload</tt> option of the <file>init.d</file> script
5387 should behave as if the configuration has been reloaded
5392 The <file>/etc/init.d</file> scripts must be treated as
5393 configuration files, either (if they are present in the
5394 package, that is, in the .deb file) by marking them as
5395 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
5396 by managing them correctly in the maintainer scripts (see
5397 <ref id="config-files">). This is important since we want
5398 to give the local system administrator the chance to adapt
5399 the scripts to the local system, e.g., to disable a
5400 service without de-installing the package, or to specify
5401 some special command line options when starting a service,
5402 while making sure her changes aren't lost during the next
5407 These scripts should not fail obscurely when the
5408 configuration files remain but the package has been
5409 removed, as configuration files remain on the system after
5410 the package has been removed. Only when <prgn>dpkg</prgn>
5411 is executed with the <tt>--purge</tt> option will
5412 configuration files be removed. In particular, as the
5413 <file>/etc/init.d/<var>package</var></file> script itself is
5414 usually a <tt>conffile</tt>, it will remain on the system
5415 if the package is removed but not purged. Therefore, you
5416 should include a <tt>test</tt> statement at the top of the
5418 <example compact="compact">
5419 test -f <var>program-executed-later-in-script</var> || exit 0
5424 Often there are some variables in the <file>init.d</file>
5425 scripts whose values control the behaviour of the scripts,
5426 and which a system administrator is likely to want to
5427 change. As the scripts themselves are frequently
5428 <tt>conffile</tt>s, modifying them requires that the
5429 administrator merge in their changes each time the package
5430 is upgraded and the <tt>conffile</tt> changes. To ease
5431 the burden on the system administrator, such configurable
5432 values should not be placed directly in the script.
5433 Instead, they should be placed in a file in
5434 <file>/etc/default</file>, which typically will have the same
5435 base name as the <file>init.d</file> script. This extra file
5436 should be sourced by the script when the script runs. It
5437 must contain only variable settings and comments in POSIX
5438 <prgn>sh</prgn> format. It may either be a
5439 <tt>conffile</tt> or a configuration file maintained by
5440 the package maintainer scripts. See <ref id="config-files">
5445 To ensure that vital configurable values are always
5446 available, the <file>init.d</file> script should set default
5447 values for each of the shell variables it uses, either
5448 before sourcing the <file>/etc/default/</file> file or
5449 afterwards using something like the <tt>:
5450 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
5451 script must behave sensibly and not fail if the
5452 <file>/etc/default</file> file is deleted.
5457 <heading>Interfacing with the initscript system</heading>
5460 Maintainers should use the abstraction layer provided by
5461 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
5462 programs to deal with initscripts in their packages'
5463 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
5464 and <prgn>postrm</prgn>.
5468 Directly managing the /etc/rc?.d links and directly
5469 invoking the <file>/etc/init.d/</file> initscripts should
5470 be done only by packages providing the initscript
5471 subsystem (such as <prgn>sysv-rct</prgn> and
5472 <prgn>file-rc</prgn>).
5476 <heading>Managing the links</heading>
5479 The program <prgn>update-rc.d</prgn> is provided for
5480 package maintainers to arrange for the proper creation and
5481 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
5482 or their functional equivalent if another method is being
5483 used. This may be used by maintainers in their packages'
5484 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
5488 You must not include any <file>/etc/rc<var>n</var>.d</file>
5489 symbolic links in the actual archive or manually create or
5490 remove the symbolic links in maintainer scripts; you must
5491 use the <prgn>update-rc.d</prgn> program instead. (The
5492 former will fail if an alternative method of maintaining
5493 runlevel information is being used.) You must not include
5494 the <file>/etc/rc<var>n</var>.d</file> directories themselves
5495 in the archive either. (Only the <tt>sysvinit</tt>
5500 By default <prgn>update-rc.d</prgn> will start services in
5501 each of the multi-user state runlevels (2, 3, 4, and 5)
5502 and stop them in the halt runlevel (0), the single-user
5503 runlevel (1) and the reboot runlevel (6). The system
5504 administrator will have the opportunity to customize
5505 runlevels by simply adding, moving, or removing the
5506 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
5507 symbolic links are being used, or by modifying
5508 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
5513 To get the default behavior for your package, put in your
5514 <prgn>postinst</prgn> script
5515 <example compact="compact">
5516 update-rc.d <var>package</var> defaults
5518 and in your <prgn>postrm</prgn>
5519 <example compact="compact">
5520 if [ "$1" = purge ]; then
5521 update-rc.d <var>package</var> remove
5523 </example>. Note that if your package changes runlevels
5524 or priority, you may have to remove and recreate the links,
5525 since otherwise the old links may persist. Refer to the
5526 documentation of <prgn>update-rc.d</prgn>.
5530 This will use a default sequence number of 20. If it does
5531 not matter when or in which order the <file>init.d</file>
5532 script is run, use this default. If it does, then you
5533 should talk to the maintainer of the <prgn>sysvinit</prgn>
5534 package or post to <tt>debian-devel</tt>, and they will
5535 help you choose a number.
5539 For more information about using <tt>update-rc.d</tt>,
5540 please consult its manpage <manref name="update-rc.d"
5546 <heading>Running initscripts</heading>
5548 The program <prgn>invoke-rc.d</prgn> is provided to make
5549 it easier for package maintainers to properly invoke an
5550 initscript, obeying runlevel and other locally-defined
5551 constraints that might limit a package's right to start,
5552 stop and otherwise manage services. This program may be
5553 used by maintainers in their packages' scripts.
5557 The use of <prgn>invoke-rc.d</prgn> to invoke the
5558 <file>/etc/init.d/*</file> initscripts is strongly
5559 recommended<footnote>
5560 In the future, the use of invoke-rc.d to invoke
5561 initscripts shall be made mandatory. Maintainers are
5562 advised to switch to invoke-rc.d as soon as
5564 </footnote>, instead of calling them directly.
5568 By default, <prgn>invoke-rc.d</prgn> will pass any
5569 action requests (start, stop, reload, restart...) to the
5570 <file>/etc/init.d</file> script, filtering out requests
5571 to start or restart a service out of its intended
5576 Most packages will simply need to change:
5577 <example compact="compact">/etc/init.d/<package>
5578 <action></example> in their <prgn>postinst</prgn>
5579 and <prgn>prerm</prgn> scripts to:
5580 <example compact="compact">
5581 if [ -x /usr/sbin/invoke-rc.d ] ; then
5582 invoke-rc.d <var>package</var> <action>
5584 /etc/init.d/<var>package</var> <action>
5590 A package should register its initscript services using
5591 <prgn>update-rc.d</prgn> before it tries to invoke them
5592 using <prgn>invoke-rc.d</prgn>. Invocation of
5593 unregistered services may fail.
5597 For more information about using
5598 <prgn>invoke-rc.d</prgn>, please consult its manpage
5599 <manref name="invoke-rc.d" section="8">.
5605 <heading>Boot-time initialization</heading>
5608 There used to be another directory, <file>/etc/rc.boot</file>,
5609 which contained scripts which were run once per machine
5610 boot. This has been deprecated in favour of links from
5611 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
5612 described in <ref id="/etc/init.d">. Packages must not
5613 place files in <file>/etc/rc.boot</file>.
5618 <heading>Example</heading>
5621 The <prgn>bind</prgn> DNS (nameserver) package wants to
5622 make sure that the nameserver is running in multiuser
5623 runlevels, and is properly shut down with the system. It
5624 puts a script in <file>/etc/init.d</file>, naming the script
5625 appropriately <tt>bind</tt>. As you can see, the script
5626 interprets the argument <tt>reload</tt> to send the
5627 nameserver a <tt>HUP</tt> signal (causing it to reload its
5628 configuration); this way the system administrator can say
5629 <tt>/etc/init.d/bind reload</tt> to reload the name
5630 server. The script has one configurable value, which can
5631 be used to pass parameters to the named program at
5632 startup; this value is read from
5633 <file>/etc/default/bind</file> (see below).
5637 <example compact="compact">
5640 # Original version by Robert Leslie
5641 # <rob@mars.org>, edited by iwj and cs
5643 test -x /usr/sbin/named || exit 0
5645 # Source defaults file.
5647 if [ -f /etc/default/bind ]; then
5654 echo -n "Starting domain name service: named"
5655 start-stop-daemon --start --quiet --exec /usr/sbin/named \
5660 echo -n "Stopping domain name service: named"
5661 start-stop-daemon --stop --quiet \
5662 --pidfile /var/run/named.pid --exec /usr/sbin/named
5666 echo -n "Restarting domain name service: named"
5667 start-stop-daemon --stop --quiet --oknodo \
5668 --pidfile /var/run/named.pid --exec /usr/sbin/named
5669 start-stop-daemon --start --verbose --exec /usr/sbin/named \
5673 force-reload|reload)
5674 echo -n "Reloading configuration of domain name service: named"
5675 start-stop-daemon --stop --signal 1 --quiet \
5676 --pidfile /var/run/named.pid --exec /usr/sbin/named
5680 echo "Usage: /etc/init.d/bind " \
5681 " {start|stop|restart|reload|force-reload}" >&2
5691 Complementing the above init script is a configuration
5692 file <file>/etc/default/bind</file>, which contains
5693 configurable parameters used by the script. This would be
5694 created by the <prgn>postinst</prgn> script if it was not
5695 already present, and removed on purge by the
5696 <prgn>postrm</prgn> script.
5697 <example compact="compact">
5698 # Specified parameters to pass to named. See named(8).
5699 # You may uncomment the following line, and edit to taste.
5705 Another example on which you can base your
5706 <file>/etc/init.d</file> scripts is found in
5707 <file>/etc/init.d/skeleton</file>.
5711 If this package is happy with the default setup from
5712 <prgn>update-rc.d</prgn>, namely an ordering number of 20
5713 and having named running in all runlevels, it can say in
5714 its <prgn>postinst</prgn>:
5715 <example compact="compact">
5716 update-rc.d bind defaults >/dev/null
5718 And in its <prgn>postrm</prgn>, to remove the links when the
5720 <example compact="compact">
5721 if [ "$1" = purge ]; then
5722 update-rc.d bind remove >/dev/null
5730 <heading>Console messages from <file>init.d</file> scripts</heading>
5733 This section describes the formats to be used for messages
5734 written to standard output by the <file>/etc/init.d</file>
5735 scripts. The intent is to improve the consistency of
5736 Debian's startup and shutdown look and feel. For this
5737 reason, please look very carefully at the details. We want
5738 the messages to have the same format in terms of wording,
5739 spaces, punctuation and case of letters.
5743 Here is a list of overall rules that you should use when you
5744 create output messages. They can be useful if you have a
5745 non-standard message that is not covered specifically in the
5752 Every message should fit in one line (fewer than 80
5753 characters), start with a capital letter and end with
5754 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
5758 If you want to express that the computer is working on
5759 something (that is, performing a specific task, not
5760 starting or stopping a program), we use an "ellipsis"
5761 (three dots: <tt>...</tt>). Note that we don't insert
5762 spaces before or after the dots. If the task has been
5763 completed we write <tt>done.</tt> and a line feed.
5767 Design your messages as if the computer is telling you
5768 what he is doing (let him be polite :-), but don't
5769 mention "him" directly. For example, if you think of
5771 <example compact="compact">
5772 I'm starting network daemons: nfsd mountd.
5775 <example compact="compact">
5776 Starting network daemons: nfsd mountd.
5783 There are standard message formats for the following
5784 situations. They should be used by the <tt>init.d</tt>
5791 <p>When daemons are started</p>
5794 If your script starts one or more daemons, the output
5795 should look like this (a single line, no leading
5797 <example compact="compact">
5798 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
5800 The <var>description</var> should describe the
5801 subsystem the daemon or set of daemons are part of,
5802 while <var>daemon-1</var> up to <var>daemon-n</var>
5803 denote each daemon's name (typically the file name of
5808 For example, the output of <file>/etc/init.d/lpd</file>
5810 <example compact="compact">
5811 Starting printer spooler: lpd.
5816 This can be achieved by saying
5817 <example compact="compact">
5818 echo -n "Starting printer spooler: lpd"
5819 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
5822 in the script. If you have more than one daemon to
5823 start, you should do the following:
5824 <example compact="compact">
5825 echo -n "Starting remote file system services:"
5826 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
5827 echo -n " mountd"; start-stop-daemon --start --quiet mountd
5828 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
5831 This makes it possible for the user to see what takes
5832 so long and when the final daemon has been started.
5833 You should be careful where to put spaces: in the
5834 example above the system administrator can easily
5835 comment out a line if he don't wants to start a
5836 specific daemon, while the displayed message still
5842 <p>When a system parameter is being set</p>
5845 If you have to set up different system parameters
5846 during the system boot, you should use this format:
5847 <example compact="compact">
5848 Setting <var>parameter</var> to "<var>value</var>".
5853 You can use a statement such as the following to get
5855 <example compact="compact">
5856 echo "Setting DNS domainname to \"$domainname\"."
5861 Note that the same symbol (<tt>"</tt>) is used for the left
5862 and right quotation marks. A grave accent (<tt>`</tt>) is
5863 not a quote character; neither is an apostrophe
5869 <p>When a daemon is stopped or restarted</p>
5872 When you stop or restart a daemon, you should issue a
5873 message identical to the startup message, except that
5874 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
5875 or <tt>Restarting</tt> respectively.
5879 For example, stopping the printer daemon will like
5881 <example compact="compact">
5882 Stopping printer spooler: lpd.
5888 <p>When something is executed</p>
5891 There are several examples where you have to run a
5892 program at system startup or shutdown to perform a
5893 specific task, for example, setting the system's clock
5894 using <prgn>netdate</prgn> or killing all processes
5895 when the system shuts down. Your message should look
5897 <example compact="compact">
5898 Doing something very useful...done.
5900 You should print the <tt>done.</tt> immediately after
5901 the job has been completed, so that the user is
5902 informed why she has to wait. You can get this
5904 <example compact="compact">
5905 echo -n "Doing something very useful..."
5914 <p>When the configuration is reloaded</p>
5917 When a daemon is forced to reload its configuration
5918 files you should use the following format:
5919 <example compact="compact">
5920 Reloading <var>description</var> configuration...done.
5922 where <var>description</var> is the same as in the
5923 daemon starting message.
5931 <heading>Cron jobs</heading>
5934 Packages must not modify the configuration file
5935 <file>/etc/crontab</file>, and they must not modify the files in
5936 <file>/var/spool/cron/crontabs</file>.</p>
5939 If a package wants to install a job that has to be executed
5940 via cron, it should place a file with the name of the
5941 package in one or more of the following directories:
5942 <example compact="compact">
5947 As these directory names imply, the files within them are
5948 executed on a daily, weekly, or monthly basis,
5949 respectively. The exact times are listed in
5950 <file>/etc/crontab</file>.</p>
5953 All files installed in any of these directories must be
5954 scripts (e.g., shell scripts or Perl scripts) so that they
5955 can easily be modified by the local system administrator.
5956 In addition, they should be treated as configuration
5961 If a certain job has to be executed more frequently than
5962 daily, the package should install a file
5963 <file>/etc/cron.d/<var>package</var></file>. This file uses the
5964 same syntax as <file>/etc/crontab</file> and is processed by
5965 <prgn>cron</prgn> automatically. The file must also be
5966 treated as a configuration file. (Note that entries in the
5967 <file>/etc/cron.d</file> directory are not handled by
5968 <prgn>anacron</prgn>. Thus, you should only use this
5969 directory for jobs which may be skipped if the system is not
5973 The scripts or crontab entries in these directories should
5974 check if all necessary programs are installed before they
5975 try to execute them. Otherwise, problems will arise when a
5976 package was removed but not purged since configuration files
5977 are kept on the system in this situation.</p>
5981 <heading>Menus</heading>
5984 The Debian <tt>menu</tt> package provides a standard
5985 interface between packages providing applications and
5986 documents, and <em>menu programs</em> (either X window
5987 managers or text-based menu programs such as
5988 <prgn>pdmenu</prgn>).
5992 All packages that provide applications that need not be
5993 passed any special command line arguments for normal
5994 operation should register a menu entry for those
5995 applications, so that users of the <tt>menu</tt> package
5996 will automatically get menu entries in their window
5997 managers, as well in shells like <tt>pdmenu</tt>.
6001 Menu entries should follow the current menu policy.
6005 The menu policy can be found in the <tt>menu-policy</tt>
6006 files in the <tt>debian-policy</tt> package.
6007 It is also available from the Debian web mirrors at
6008 <tt><url name="/doc/packaging-manuals/menu-policy/"
6009 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>
6010 and from the Debian archive mirrors at
6011 <tt><url name="/doc/package-developer/menu-policy.txt.gz"
6012 id="http://ftp.debian.org/debian/doc/package-developer/menu-policy.txt.gz"></tt>.
6016 Please also refer to the <em>Debian Menu System</em>
6017 documentation that comes with the <tt>menu</tt> package for
6018 information about how to register your applications and web
6024 <heading>Multimedia handlers</heading>
6027 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6028 is a mechanism for encoding files and data streams and
6029 providing meta-information about them, in particular their
6030 type (e.g. audio or video) and format (e.g. PNG, HTML,
6035 Registration of MIME type handlers allows programs like mail
6036 user agents and web browsers to invoke these handlers to
6037 view, edit or display MIME types they don't support directly.
6041 Packages which provide the ability to view/show/play,
6042 compose, edit or print MIME types should register themselves
6043 as such following the current MIME support policy.
6047 The MIME support policy can be found in the <tt>mime-policy</tt>
6048 files in the <tt>debian-policy</tt> package.
6049 It is also available from the Debian web mirrors at
6050 <tt><url name="/doc/packaging-manuals/mime-policy/"
6051 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>
6052 and from the Debian archive mirrors at
6053 <tt><url name="/doc/package-developer/mime-policy.txt.gz"
6054 id="http://ftp.debian.org/debian/doc/package-developer/mime-policy.txt.gz"></tt>.
6060 <heading>Keyboard configuration</heading>
6063 To achieve a consistent keyboard configuration so that all
6064 applications interpret a keyboard event the same way, all
6065 programs in the Debian distribution must be configured to
6066 comply with the following guidelines.
6070 The following keys must have the specified interpretations:
6073 <tag><tt><--</tt></tag>
6074 <item>delete the character to the left of the cursor</item>
6076 <tag><tt>Delete</tt></tag>
6077 <item>delete the character to the right of the cursor</item>
6079 <tag><tt>Control+H</tt></tag>
6080 <item>emacs: the help prefix</item>
6083 The interpretation of any keyboard events should be
6084 independent of the terminal that is used, be it a virtual
6085 console, an X terminal emulator, an rlogin/telnet session,
6090 The following list explains how the different programs
6091 should be set up to achieve this:
6097 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6101 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6105 X translations are set up to make
6106 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6107 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6108 is the vt220 escape code for the "delete character"
6109 key). This must be done by loading the X resources
6110 using <prgn>xrdb</prgn> on all local X displays, not
6111 using the application defaults, so that the
6112 translation resources used correspond to the
6113 <prgn>xmodmap</prgn> settings.
6117 The Linux console is configured to make
6118 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6119 generate <tt>ESC [ 3 ~</tt>.
6123 X applications are configured so that <tt><</tt>
6124 deletes left, and <tt>Delete</tt> deletes right. Motif
6125 applications already work like this.
6129 Terminals should have <tt>stty erase ^?</tt> .
6133 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6134 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6135 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6139 Emacs is programmed to map <tt>KB_Backspace</tt> or
6140 the <tt>stty erase</tt> character to
6141 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6142 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6143 <tt>^H</tt> to <tt>help</tt> as always.
6147 Other applications use the <tt>stty erase</tt>
6148 character and <tt>kdch1</tt> for the two delete keys,
6149 with ASCII DEL being "delete previous character" and
6150 <tt>kdch1</tt> being "delete character under
6158 This will solve the problem except for the following
6165 Some terminals have a <tt><--</tt> key that cannot
6166 be made to produce anything except <tt>^H</tt>. On
6167 these terminals Emacs help will be unavailable on
6168 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6169 character takes precedence in Emacs, and has been set
6170 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6171 available) can be used instead.
6175 Some operating systems use <tt>^H</tt> for <tt>stty
6176 erase</tt>. However, modern telnet versions and all
6177 rlogin versions propagate <tt>stty</tt> settings, and
6178 almost all UNIX versions honour <tt>stty erase</tt>.
6179 Where the <tt>stty</tt> settings are not propagated
6180 correctly, things can be made to work by using
6181 <tt>stty</tt> manually.
6185 Some systems (including previous Debian versions) use
6186 <prgn>xmodmap</prgn> to arrange for both
6187 <tt><--</tt> and <tt>Delete</tt> to generate
6188 <tt>KB_Delete</tt>. We can change the behavior of
6189 their X clients using the same X resources that we use
6190 to do it for our own clients, or configure our clients
6191 using their resources when things are the other way
6192 around. On displays configured like this
6193 <tt>Delete</tt> will not work, but <tt><--</tt>
6198 Some operating systems have different <tt>kdch1</tt>
6199 settings in their <tt>terminfo</tt> database for
6200 <tt>xterm</tt> and others. On these systems the
6201 <tt>Delete</tt> key will not work correctly when you
6202 log in from a system conforming to our policy, but
6203 <tt><--</tt> will.
6210 <heading>Environment variables</heading>
6213 A program must not depend on environment variables to get
6214 reasonable defaults. (That's because these environment
6215 variables would have to be set in a system-wide
6216 configuration file like <file>/etc/profile</file>, which is not
6217 supported by all shells.)
6221 If a program usually depends on environment variables for its
6222 configuration, the program should be changed to fall back to
6223 a reasonable default configuration if these environment
6224 variables are not present. If this cannot be done easily
6225 (e.g., if the source code of a non-free program is not
6226 available), the program must be replaced by a small
6227 "wrapper" shell script which sets the environment variables
6228 if they are not already defined, and calls the original program.
6232 Here is an example of a wrapper script for this purpose:
6234 <example compact="compact">
6236 BAR=${BAR:-/var/lib/fubar}
6238 exec /usr/lib/foo/foo "$@"
6243 Furthermore, as <file>/etc/profile</file> is a configuration
6244 file of the <prgn>base-files</prgn> package, other packages must
6245 not put any environment variables or other commands into that
6254 <heading>Files</heading>
6257 <heading>Binaries</heading>
6260 Two different packages must not install programs with
6261 different functionality but with the same filenames. (The
6262 case of two programs having the same functionality but
6263 different implementations is handled via "alternatives" or
6264 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6265 <ref id="conflicts"> respectively.) If this case happens,
6266 one of the programs must be renamed. The maintainers should
6267 report this to the <tt>debian-devel</tt> mailing list and
6268 try to find a consensus about which program will have to be
6269 renamed. If a consensus cannot be reached, <em>both</em>
6270 programs must be renamed.
6274 By default, when a package is being built, any binaries
6275 created should include debugging information, as well as
6276 being compiled with optimization. You should also turn on
6277 as many reasonable compilation warnings as possible; this
6278 makes life easier for porters, who can then look at build
6279 logs for possible problems. For the C programming language,
6280 this means the following compilation parameters should be
6282 <example compact="compact">
6284 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6286 install -s # (or use strip on the files in debian/tmp)
6291 Note that by default all installed binaries should be stripped,
6292 either by using the <tt>-s</tt> flag to
6293 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6294 the binaries after they have been copied into
6295 <file>debian/tmp</file> but before the tree is made into a
6300 Although binaries in the build tree should be compiled with
6301 debugging information by default, it can often be difficult
6302 to debug programs if they are also subjected to compiler
6303 optimization. For this reason, it is recommended to support
6304 the standardized environment
6305 variable <tt>DEB_BUILD_OPTIONS</tt>. This variable can
6306 contain several flags to change how a package is compiled
6314 The presence of this string means that the package
6315 should be compiled with a minimum of optimization.
6316 For C programs, it is best to add <tt>-O0</tt>
6317 to <tt>CFLAGS</tt> (although this is usually the
6318 default). Some programs might fail to build or run at
6319 this level of optimization; it may be necessary to
6320 use <tt>-O1</tt>, for example.
6324 This string means that the debugging symbols should
6325 not be stripped from the binary during installation,
6326 so that debugging information may be included in the package.
6332 The following makefile snippet is an example of how one may
6333 implement the build options; you will probably have to
6334 massage this example in order to make it work for your
6336 <example compact="compact">
6339 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
6340 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
6341 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
6342 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
6344 ifneq (,$(findstring noopt,$(DEB_BUILD_OPTIONS)))
6349 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
6350 INSTALL_PROGRAM += -s
6356 It is up to the package maintainer to decide what
6357 compilation options are best for the package. Certain
6358 binaries (such as computationally-intensive programs) will
6359 function better with certain flags (<tt>-O3</tt>, for
6360 example); feel free to use them. Please use good judgment
6361 here. Don't use flags for the sake of it; only use them
6362 if there is good reason to do so. Feel free to override
6363 the upstream author's ideas about which compilation
6364 options are best: they are often inappropriate for our
6370 <sect id="libraries">
6371 <heading>Libraries</heading>
6374 The shared version of a library must be compiled with
6375 <tt>-fPIC</tt>, and the static version must not be. In other
6376 words, each source unit (<tt>*.c</tt>, for example, for C files)
6377 will need to be compiled twice.
6381 You must specify the gcc option <tt>-D_REENTRANT</tt>
6382 when building a library (either static or shared) to make
6383 the library compatible with LinuxThreads.
6387 Although not enforced by the build tools, shared libraries
6388 must be linked against all libraries that they use symbols from
6389 in the same way that binaries are. This ensures the correct
6390 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
6391 system and guarantees that all libraries can be safely opened
6392 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
6393 option <tt>-Wl,-z,defs</tt> when building a shared library.
6394 Since this option enforces symbol resolution at build time,
6395 a missing library reference will be caught early as a fatal
6400 All installed shared libraries should be stripped with
6401 <example compact="compact">
6402 strip --strip-unneeded <var>your-lib</var>
6404 (The option <tt>--strip-unneeded</tt> makes
6405 <prgn>strip</prgn> remove only the symbols which aren't
6406 needed for relocation processing.) Shared libraries can
6407 function perfectly well when stripped, since the symbols for
6408 dynamic linking are in a separate part of the ELF object
6410 You might also want to use the options
6411 <tt>--remove-section=.comment</tt> and
6412 <tt>--remove-section=.note</tt> on both shared libraries
6413 and executables, and <tt>--strip-debug</tt> on static
6419 Note that under some circumstances it may be useful to
6420 install a shared library unstripped, for example when
6421 building a separate package to support debugging.
6425 Shared object files (often <file>.so</file> files) that are not
6426 public libraries, that is, they are not meant to be linked
6427 to by third party executables (binaries of other packages),
6428 should be installed in subdirectories of the
6429 <file>/usr/lib</file> directory. Such files are exempt from the
6430 rules that govern ordinary shared libraries, except that
6431 they must not be installed executable and should be
6433 A common example are the so-called "plug-ins",
6434 internal shared objects that are dynamically loaded by
6435 programs using <manref name="dlopen" section="3">.
6440 Packages containing shared libraries that may be linked to
6441 by other packages' binaries, but which for some
6442 <em>compelling</em> reason can not be installed in
6443 <file>/usr/lib</file> directory, may install the shared library
6444 files in subdirectories of the <file>/usr/lib</file> directory,
6445 in which case they should arrange to add that directory in
6446 <file>/etc/ld.so.conf</file> in the package's post-installation
6447 script, and remove it in the package's post-removal script.
6451 An ever increasing number of packages are using
6452 <prgn>libtool</prgn> to do their linking. The latest GNU
6453 libtools (>= 1.3a) can take advantage of the metadata in the
6454 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
6455 files). The main advantage of <prgn>libtool</prgn>'s
6456 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
6457 store and subsequently access metadata with respect to the
6458 libraries it builds. <prgn>libtool</prgn> will search for
6459 those files, which contain a lot of useful information about
6460 a library (such as library dependency information for static
6461 linking). Also, they're <em>essential</em> for programs
6462 using <tt>libltdl</tt>.<footnote>
6463 Although <prgn>libtool</prgn> is fully capable of
6464 linking against shared libraries which don't have
6465 <tt>.la</tt> files, as it is a mere shell script it can
6466 add considerably to the build time of a
6467 <prgn>libtool</prgn>-using package if that shell script
6468 has to derive all this information from first principles
6469 for each library every time it is linked. With the
6470 advent of <prgn>libtool</prgn> version 1.4 (and to a
6471 lesser extent <prgn>libtool</prgn> version 1.3), the
6472 <file>.la</file> files also store information about
6473 inter-library dependencies which cannot necessarily be
6474 derived after the <file>.la</file> file is deleted.
6479 Packages that use <prgn>libtool</prgn> to create shared
6480 libraries should include the <file>.la</file> files in the
6481 <tt>-dev</tt> package, unless the package relies on
6482 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
6483 the <tt>.la</tt> files must go in the run-time library
6488 You must make sure that you use only released versions of
6489 shared libraries to build your packages; otherwise other
6490 users will not be able to run your binaries
6491 properly. Producing source packages that depend on
6492 unreleased compilers is also usually a bad
6499 <heading>Shared libraries</heading>
6501 This section has moved to <ref id="sharedlibs">.
6507 <heading>Scripts</heading>
6510 All command scripts, including the package maintainer
6511 scripts inside the package and used by <prgn>dpkg</prgn>,
6512 should have a <tt>#!</tt> line naming the shell to be used
6517 In the case of Perl scripts this should be
6518 <tt>#!/usr/bin/perl</tt>.
6522 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
6523 should almost certainly start with <tt>set -e</tt> so that
6524 errors are detected. Every script should use
6525 <tt>set -e</tt> or check the exit status of <em>every</em>
6530 The standard shell interpreter <file>/bin/sh</file> can be a
6531 symbolic link to any POSIX compatible shell, if <tt>echo
6532 -n</tt> does not generate a newline.<footnote>
6533 Debian policy specifies POSIX behavior for
6534 <file>/bin/sh</file>, but <tt>echo -n</tt> has widespread
6535 use in the Linux community (in particular including this
6536 policy, the Linux kernel source, many Debian scripts,
6537 etc.). This <tt>echo -n</tt> mechanism is valid but not
6538 required under POSIX, hence this explicit addition.
6539 Also, rumour has it that this shall be mandated under
6542 Thus, shell scripts specifying <file>/bin/sh</file> as
6543 interpreter should only use POSIX features. If a script
6544 requires non-POSIX features from the shell interpreter, the
6545 appropriate shell must be specified in the first line of the
6546 script (e.g., <tt>#!/bin/bash</tt>) and the package must
6547 depend on the package providing the shell (unless the shell
6548 package is marked "Essential", as in the case of
6553 You may wish to restrict your script to POSIX features when
6554 possible so that it may use <file>/bin/sh</file> as its
6555 interpreter. If your script works with <prgn>dash</prgn>
6556 (originally called <prgn>ash</prgn>), it's probably POSIX
6557 compliant, but if you are in doubt, use
6558 <file>/bin/bash</file>.
6562 Perl scripts should check for errors when making any
6563 system calls, including <tt>open</tt>, <tt>print</tt>,
6564 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
6568 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
6569 scripting languages. See <em>Csh Programming Considered
6570 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
6571 can be found at <url id="http://language.perl.com/versus/csh.whynot">.
6572 If an upstream package comes with <prgn>csh</prgn> scripts
6573 then you must make sure that they start with
6574 <tt>#!/bin/csh</tt> and make your package depend on the
6575 <prgn>c-shell</prgn> virtual package.
6579 Any scripts which create files in world-writeable
6580 directories (e.g., in <file>/tmp</file>) must use a
6581 mechanism which will fail if a file with the same name
6586 The Debian base system provides the <prgn>tempfile</prgn>
6587 and <prgn>mktemp</prgn> utilities for use by scripts for
6594 <heading>Symbolic links</heading>
6597 In general, symbolic links within a top-level directory
6598 should be relative, and symbolic links pointing from one
6599 top-level directory into another should be absolute. (A
6600 top-level directory is a sub-directory of the root
6601 directory <file>/</file>.)
6605 In addition, symbolic links should be specified as short as
6606 possible, i.e., link targets like <file>foo/../bar</file> are
6611 Note that when creating a relative link using
6612 <prgn>ln</prgn> it is not necessary for the target of the
6613 link to exist relative to the working directory you're
6614 running <prgn>ln</prgn> from, nor is it necessary to change
6615 directory to the directory where the link is to be made.
6616 Simply include the string that should appear as the target
6617 of the link (this will be a pathname relative to the
6618 directory in which the link resides) as the first argument
6623 For example, in your <prgn>Makefile</prgn> or
6624 <file>debian/rules</file>, you can do things like:
6625 <example compact="compact">
6626 ln -fs gcc $(prefix)/bin/cc
6627 ln -fs gcc debian/tmp/usr/bin/cc
6628 ln -fs ../sbin/sendmail $(prefix)/bin/runq
6629 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
6634 A symbolic link pointing to a compressed file should always
6635 have the same file extension as the referenced file. (For
6636 example, if a file <file>foo.gz</file> is referenced by a
6637 symbolic link, the filename of the link has to end with
6638 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
6643 <heading>Device files</heading>
6646 Packages must not include device files in the package file
6651 If a package needs any special device files that are not
6652 included in the base system, it must call
6653 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
6654 after notifying the user<footnote>
6655 This notification could be done via a (low-priority)
6656 debconf message, or an echo (printf) statement.
6661 Packages must not remove any device files in the
6662 <prgn>postrm</prgn> or any other script. This is left to the
6663 system administrator.
6667 Debian uses the serial devices
6668 <file>/dev/ttyS*</file>. Programs using the old
6669 <file>/dev/cu*</file> devices should be changed to use
6670 <file>/dev/ttyS*</file>.
6674 <sect id="config-files">
6675 <heading>Configuration files</heading>
6678 <heading>Definitions</heading>
6682 <tag>configuration file</tag>
6684 A file that affects the operation of a program, or
6685 provides site- or host-specific information, or
6686 otherwise customizes the behavior of a program.
6687 Typically, configuration files are intended to be
6688 modified by the system administrator (if needed or
6689 desired) to conform to local policy or to provide
6690 more useful site-specific behavior.
6693 <tag><tt>conffile</tt></tag>
6695 A file listed in a package's <tt>conffiles</tt>
6696 file, and is treated specially by <prgn>dpkg</prgn>
6697 (see <ref id="configdetails">).
6703 The distinction between these two is important; they are
6704 not interchangeable concepts. Almost all
6705 <tt>conffile</tt>s are configuration files, but many
6706 configuration files are not <tt>conffiles</tt>.
6710 Note that a script that embeds configuration information
6711 (such as most of the files in <file>/etc/default</file> and
6712 <file>/etc/cron.{daily,weekly,monthly}</file>) is de-facto a
6713 configuration file and should be treated as such.
6718 <heading>Location</heading>
6721 Any configuration files created or used by your package
6722 must reside in <file>/etc</file>. If there are several,
6723 consider creating a subdirectory of <file>/etc</file>
6724 named after your package.
6728 If your package creates or uses configuration files
6729 outside of <file>/etc</file>, and it is not feasible to modify
6730 the package to use <file>/etc</file> directly, put the files
6731 in <file>/etc</file> and create symbolic links to those files
6732 from the location that the package requires.
6737 <heading>Behavior</heading>
6740 Configuration file handling must conform to the following
6742 <list compact="compact">
6744 local changes must be preserved during a package
6748 configuration files must be preserved when the
6749 package is removed, and only deleted when the
6756 The easy way to achieve this behavior is to make the
6757 configuration file a <tt>conffile</tt>. This is
6758 appropriate only if it is possible to distribute a default
6759 version that will work for most installations, although
6760 some system administrators may choose to modify it. This
6761 implies that the default version will be part of the
6762 package distribution, and must not be modified by the
6763 maintainer scripts during installation (or at any other
6768 In order to ensure that local changes are preserved
6769 correctly, no package may contain or make hard links to
6770 conffiles.<footnote>
6771 Rationale: There are two problems with hard links.
6772 The first is that some editors break the link while
6773 editing one of the files, so that the two files may
6774 unwittingly become unlinked and different. The second
6775 is that <prgn>dpkg</prgn> might break the hard link
6776 while upgrading <tt>conffile</tt>s.
6781 The other way to do it is via the maintainer scripts. In
6782 this case, the configuration file must not be listed as a
6783 <tt>conffile</tt> and must not be part of the package
6784 distribution. If the existence of a file is required for
6785 the package to be sensibly configured it is the
6786 responsibility of the package maintainer to provide
6787 maintainer scripts which correctly create, update and
6788 maintain the file and remove it on purge. (See <ref
6789 id="maintainerscripts"> for more information.) These
6790 scripts must be idempotent (i.e., must work correctly if
6791 <prgn>dpkg</prgn> needs to re-run them due to errors
6792 during installation or removal), must cope with all the
6793 variety of ways <prgn>dpkg</prgn> can call maintainer
6794 scripts, must not overwrite or otherwise mangle the user's
6795 configuration without asking, must not ask unnecessary
6796 questions (particularly during upgrades), and otherwise be
6801 The scripts are not required to configure every possible
6802 option for the package, but only those necessary to get
6803 the package running on a given system. Ideally the
6804 sysadmin should not have to do any configuration other
6805 than that done (semi-)automatically by the
6806 <prgn>postinst</prgn> script.
6810 A common practice is to create a script called
6811 <file><var>package</var>-configure</file> and have the
6812 package's <prgn>postinst</prgn> call it if and only if the
6813 configuration file does not already exist. In certain
6814 cases it is useful for there to be an example or template
6815 file which the maintainer scripts use. Such files should
6816 be in <file>/usr/share/<var>package</var></file> or
6817 <file>/usr/lib/<var>package</var></file> (depending on whether
6818 they are architecture-independent or not). There should
6819 be symbolic links to them from
6820 <file>/usr/share/doc/<var>package</var>/examples</file> if
6821 they are examples, and should be perfectly ordinary
6822 <prgn>dpkg</prgn>-handled files (<em>not</em>
6823 configuration files).
6827 These two styles of configuration file handling must
6828 not be mixed, for that way lies madness:
6829 <prgn>dpkg</prgn> will ask about overwriting the file
6830 every time the package is upgraded.
6835 <heading>Sharing configuration files</heading>
6838 Packages which specify the same file as a
6839 <tt>conffile</tt> must be tagged as <em>conflicting</em>
6840 with each other. (This is an instance of the general rule
6841 about not sharing files. Note that neither alternatives
6842 nor diversions are likely to be appropriate in this case;
6843 in particular, <prgn>dpkg</prgn> does not handle diverted
6844 <tt>conffile</tt>s well.)
6848 The maintainer scripts must not alter a <tt>conffile</tt>
6849 of <em>any</em> package, including the one the scripts
6854 If two or more packages use the same configuration file
6855 and it is reasonable for both to be installed at the same
6856 time, one of these packages must be defined as
6857 <em>owner</em> of the configuration file, i.e., it will be
6858 the package which handles that file as a configuration
6859 file. Other packages that use the configuration file must
6860 depend on the owning package if they require the
6861 configuration file to operate. If the other package will
6862 use the configuration file if present, but is capable of
6863 operating without it, no dependency need be declared.
6867 If it is desirable for two or more related packages to
6868 share a configuration file <em>and</em> for all of the
6869 related packages to be able to modify that configuration
6870 file, then the following should be done:
6871 <enumlist compact="compact">
6873 One of the related packages (the "owning" package)
6874 will manage the configuration file with maintainer
6875 scripts as described in the previous section.
6878 The owning package should also provide a program
6879 that the other packages may use to modify the
6883 The related packages must use the provided program
6884 to make any desired modifications to the
6885 configuration file. They should either depend on
6886 the core package to guarantee that the configuration
6887 modifier program is available or accept gracefully
6888 that they cannot modify the configuration file if it
6889 is not. (This is in addition to the fact that the
6890 configuration file may not even be present in the
6897 Sometimes it's appropriate to create a new package which
6898 provides the basic infrastructure for the other packages
6899 and which manages the shared configuration files. (The
6900 <tt>sgml-base</tt> package is a good example.)
6905 <heading>User configuration files ("dotfiles")</heading>
6908 The files in <file>/etc/skel</file> will automatically be
6909 copied into new user accounts by <prgn>adduser</prgn>.
6910 No other program should reference the files in
6911 <file>/etc/skel</file>.
6915 Therefore, if a program needs a dotfile to exist in
6916 advance in <file>$HOME</file> to work sensibly, that dotfile
6917 should be installed in <file>/etc/skel</file> and treated as a
6922 However, programs that require dotfiles in order to
6923 operate sensibly are a bad thing, unless they do create
6924 the dotfiles themselves automatically.
6928 Furthermore, programs should be configured by the Debian
6929 default installation to behave as closely to the upstream
6930 default behaviour as possible.
6934 Therefore, if a program in a Debian package needs to be
6935 configured in some way in order to operate sensibly, that
6936 should be done using a site-wide configuration file placed
6937 in <file>/etc</file>. Only if the program doesn't support a
6938 site-wide default configuration and the package maintainer
6939 doesn't have time to add it may a default per-user file be
6940 placed in <file>/etc/skel</file>.
6944 <file>/etc/skel</file> should be as empty as we can make it.
6945 This is particularly true because there is no easy (or
6946 necessarily desirable) mechanism for ensuring that the
6947 appropriate dotfiles are copied into the accounts of
6948 existing users when a package is installed.
6954 <heading>Log files</heading>
6956 Log files should usually be named
6957 <file>/var/log/<var>package</var>.log</file>. If you have many
6958 log files, or need a separate directory for permission
6959 reasons (<file>/var/log</file> is writable only by
6960 <file>root</file>), you should usually create a directory named
6961 <file>/var/log/<var>package</var></file> and place your log
6966 Log files must be rotated occasionally so that they don't
6967 grow indefinitely; the best way to do this is to drop a log
6968 rotation configuration file into the directory
6969 <file>/etc/logrotate.d</file> and use the facilities provided by
6970 logrotate.<footnote>
6972 The traditional approach to log files has been to set up
6973 <em>ad hoc</em> log rotation schemes using simple shell
6974 scripts and cron. While this approach is highly
6975 customizable, it requires quite a lot of sysadmin work.
6976 Even though the original Debian system helped a little
6977 by automatically installing a system which can be used
6978 as a template, this was deemed not enough.
6982 The use of <prgn>logrotate</prgn>, a program developed
6983 by Red Hat, is better, as it centralizes log management.
6984 It has both a configuration file
6985 (<file>/etc/logrotate.conf</file>) and a directory where
6986 packages can drop their individual log rotation
6987 configurations (<file>/etc/logrotate.d</file>).
6990 Here is a good example for a logrotate config
6991 file (for more information see <manref name="logrotate"
6993 <example compact="compact">
6994 /var/log/foo/*.log {
6999 /etc/init.d/foo force-reload
7003 This rotates all files under <file>/var/log/foo</file>, saves 12
7004 compressed generations, and forces the daemon to reload its
7005 configuration information after the log rotation.
7009 Log files should be removed when the package is
7010 purged (but not when it is only removed). This should be
7011 done by the <prgn>postrm</prgn> script when it is called
7012 with the argument <tt>purge</tt> (see <ref
7013 id="removedetails">).
7018 <heading>Permissions and owners</heading>
7021 The rules in this section are guidelines for general use.
7022 If necessary you may deviate from the details below.
7023 However, if you do so you must make sure that what is done
7024 is secure and you should try to be as consistent as possible
7025 with the rest of the system. You should probably also
7026 discuss it on <prgn>debian-devel</prgn> first.
7030 Files should be owned by <tt>root.root</tt>, and made
7031 writable only by the owner and universally readable (and
7032 executable, if appropriate), that is mode 644 or 755.
7036 Directories should be mode 755 or (for group-writability)
7037 mode 2775. The ownership of the directory should be
7038 consistent with its mode: if a directory is mode 2775, it
7039 should be owned by the group that needs write access to
7044 Setuid and setgid executables should be mode 4755 or 2755
7045 respectively, and owned by the appropriate user or group.
7046 They should not be made unreadable (modes like 4711 or
7047 2711 or even 4111); doing so achieves no extra security,
7048 because anyone can find the binary in the freely available
7049 Debian package; it is merely inconvenient. For the same
7050 reason you should not restrict read or execute permissions
7051 on non-set-id executables.
7055 Some setuid programs need to be restricted to particular
7056 sets of users, using file permissions. In this case they
7057 should be owned by the uid to which they are set-id, and by
7058 the group which should be allowed to execute them. They
7059 should have mode 4754; again there is no point in making
7060 them unreadable to those users who must not be allowed to
7065 It is possible to arrange that the system administrator can
7066 reconfigure the package to correspond to their local
7067 security policy by changing the permissions on a binary:
7068 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7069 described below.<footnote>
7070 Ordinary files installed by <prgn>dpkg</prgn> (as
7071 opposed to <tt>conffile</tt>s and other similar objects)
7072 normally have their permissions reset to the distributed
7073 permissions when the package is reinstalled. However,
7074 the use of <prgn>dpkg-statoverride</prgn> overrides this
7075 default behaviour. If you use this method, you should
7076 remember to describe <prgn>dpkg-statoverride</prgn> in
7077 the package documentation; being a relatively new
7078 addition to Debian, it is probably not yet well-known.
7080 Another method you should consider is to create a group for
7081 people allowed to use the program(s) and make any setuid
7082 executables executable only by that group.
7086 If you need to create a new user or group for your package
7087 there are two possibilities. Firstly, you may need to
7088 make some files in the binary package be owned by this
7089 user or group, or you may need to compile the user or
7090 group id (rather than just the name) into the binary
7091 (though this latter should be avoided if possible, as in
7092 this case you need a statically allocated id).</p>
7095 If you need a statically allocated id, you must ask for a
7096 user or group id from the <tt>base-passwd</tt> maintainer,
7097 and must not release the package until you have been
7098 allocated one. Once you have been allocated one you must
7099 either make the package depend on a version of the
7100 <tt>base-passwd</tt> package with the id present in
7101 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7102 your package to create the user or group itself with the
7103 correct id (using <tt>adduser</tt>) in its
7104 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7105 the <prgn>postinst</prgn> is to be preferred if it is
7106 possible, otherwise a pre-dependency will be needed on the
7107 <tt>adduser</tt> package.)
7111 On the other hand, the program might be able to determine
7112 the uid or gid from the user or group name at runtime, so
7113 that a dynamically allocated id can be used. In this case
7114 you should choose an appropriate user or group name,
7115 discussing this on <prgn>debian-devel</prgn> and checking
7116 with the <package/base-passwd/ maintainer that it is unique and that
7117 they do not wish you to use a statically allocated id
7118 instead. When this has been checked you must arrange for
7119 your package to create the user or group if necessary using
7120 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7121 <prgn>postinst</prgn> script (again, the latter is to be
7122 preferred if it is possible).
7126 Note that changing the numeric value of an id associated
7127 with a name is very difficult, and involves searching the
7128 file system for all appropriate files. You need to think
7129 carefully whether a static or dynamic id is required, since
7130 changing your mind later will cause problems.
7133 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7135 This section is not intended as policy, but as a
7136 description of the use of <prgn>dpkg-statoverride</prgn>.
7140 <prgn>dpkg-statoverride</prgn> is a replacement for the
7141 deprecated <tt>suidmanager</tt> package. Packages which
7142 previously used <tt>suidmanager</tt> should have a
7143 <tt>Conflicts: suidmanager (<< 0.50)</tt> entry (or even
7144 <tt>(<< 0.52)</tt>), and calls to <tt>suidregister</tt>
7145 and <tt>suidunregister</tt> should now be simply removed
7146 from the maintainer scripts.
7150 If a system administrator wishes to have a file (or
7151 directory or other such thing) installed with owner and
7152 permissions different from those in the distributed Debian
7153 package, he can use the <prgn>dpkg-statoverride</prgn>
7154 program to instruct <prgn>dpkg</prgn> to use the different
7155 settings every time the file is installed. Thus the
7156 package maintainer should distribute the files with their
7157 normal permissions, and leave it for the system
7158 administrator to make any desired changes. For example, a
7159 daemon which is normally required to be setuid root, but
7160 in certain situations could be used without being setuid,
7161 should be installed setuid in the <tt>.deb</tt>. Then the
7162 local system administrator can change this if they wish.
7163 If there are two standard ways of doing it, the package
7164 maintainer can use <tt>debconf</tt> to find out the
7165 preference, and call <prgn>dpkg-statoverride</prgn> in the
7166 maintainer script if necessary to accommodate the system
7167 administrator's choice.
7171 Given the above, <prgn>dpkg-statoverride</prgn> is
7172 essentially a tool for system administrators and would not
7173 normally be needed in the maintainer scripts. There is
7174 one type of situation, though, where calls to
7175 <prgn>dpkg-statoverride</prgn> would be needed in the
7176 maintainer scripts, and that involves packages which use
7177 dynamically allocated user or group ids. In such a
7178 situation, something like the following idiom can be very
7179 helpful in the package's <prgn>postinst</prgn>, where
7180 <tt>sysuser</tt> is a dynamically allocated id:
7182 for i in /usr/bin/foo /usr/sbin/bar
7184 if ! dpkg-statoverride --list $i >/dev/null
7186 dpkg-statoverride --update --add sysuser root 4755 $i
7190 The corresponding <tt>dpkg-statoverride --remove</tt>
7191 calls can then be made unconditionally when the package is
7199 <chapt id="customized-programs">
7200 <heading>Customized programs</heading>
7202 <sect id="arch-spec">
7203 <heading>Architecture specification strings</heading>
7206 If a program needs to specify an <em>architecture specification
7207 string</em> in some place, the following format should be
7208 used: <var>arch</var>-<var>os</var><footnote>
7209 The following architectures and operating systems are
7210 currently recognised by <prgn>dpkg-archictecture</prgn>.
7211 The architecture, <tt><var>arch</var></tt>, is one of
7212 the following: <tt>alpha</tt>, <tt>arm</tt>,
7213 <tt>hppa</tt>, <tt>i386</tt>, <tt>ia64</tt>,
7214 <tt>m68k</tt>, <tt>mips</tt>, <tt>mipsel</tt>,
7215 <tt>powerpc</tt>, <tt>s390</tt>, <tt>sh</tt>,
7216 <tt>sheb</tt>, <tt>sparc</tt> and <tt>sparc64</tt>. The
7217 operating system, <tt><var>os</var></tt>, is one of:
7218 <tt>linux</tt>, <tt>gnu</tt>, <tt>freebsd</tt> and
7219 <tt>openbsd</tt>. Use of <tt>gnu</tt> in this string is
7220 reserved for the GNU/Hurd operating system.
7225 Note that we don't want to use
7226 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7227 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7228 since this would make our programs incompatible with other
7229 Linux distributions. We also don't use something like
7230 <tt><var>arch</var>-unknown-linux</tt>, since the
7231 <tt>unknown</tt> does not look very good.
7236 <heading>Daemons</heading>
7239 The configuration files <file>/etc/services</file>,
7240 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7241 by the <prgn>netbase</prgn> package and must not be modified
7246 If a package requires a new entry in one of these files, the
7247 maintainer should get in contact with the
7248 <prgn>netbase</prgn> maintainer, who will add the entries
7249 and release a new version of the <prgn>netbase</prgn>
7254 The configuration file <file>/etc/inetd.conf</file> must not be
7255 modified by the package's scripts except via the
7256 <prgn>update-inetd</prgn> script or the
7257 <file>DebianNet.pm</file> Perl module. See their documentation
7258 for details on how to add entries.
7262 If a package wants to install an example entry into
7263 <file>/etc/inetd.conf</file>, the entry must be preceded with
7264 exactly one hash character (<tt>#</tt>). Such lines are
7265 treated as "commented out by user" by the
7266 <prgn>update-inetd</prgn> script and are not changed or
7267 activated during package updates.
7272 <heading>Using pseudo-ttys and modifying wtmp, utmp and
7276 Some programs need to create pseudo-ttys. This should be done
7277 using Unix98 ptys if the C library supports it. The resulting
7278 program must not be installed setuid root, unless that
7279 is required for other functionality.
7283 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
7284 <file>/var/log/lastlog</file> must be installed writeable by
7285 group <tt>utmp</tt>. Programs which need to modify those
7286 files must be installed setgid <tt>utmp</tt>.
7291 <heading>Editors and pagers</heading>
7294 Some programs have the ability to launch an editor or pager
7295 program to edit or display a text document. Since there are
7296 lots of different editors and pagers available in the Debian
7297 distribution, the system administrator and each user should
7298 have the possibility to choose his/her preferred editor and
7303 In addition, every program should choose a good default
7304 editor/pager if none is selected by the user or system
7309 Thus, every program that launches an editor or pager must
7310 use the EDITOR or PAGER environment variable to determine
7311 the editor or pager the user wishes to use. If these
7312 variables are not set, the programs <file>/usr/bin/editor</file>
7313 and <file>/usr/bin/pager</file> should be used, respectively.
7317 These two files are managed through the <prgn>dpkg</prgn>
7318 "alternatives" mechanism. Thus every package providing an
7319 editor or pager must call the
7320 <prgn>update-alternatives</prgn> script to register these
7325 If it is very hard to adapt a program to make use of the
7326 EDITOR or PAGER variables, that program may be configured to
7327 use <file>/usr/bin/sensible-editor</file> and
7328 <file>/usr/bin/sensible-pager</file> as the editor or pager
7329 program respectively. These are two scripts provided in the
7330 Debian base system that check the EDITOR and PAGER variables
7331 and launch the appropriate program, and fall back to
7332 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
7333 variable is not set.
7337 A program may also use the VISUAL environment variable to
7338 determine the user's choice of editor. If it exists, it
7339 should take precedence over EDITOR. This is in fact what
7340 <file>/usr/bin/sensible-editor</file> does.
7344 It is not required for a package to depend on
7345 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
7346 package to provide such virtual packages.<footnote>
7347 The Debian base system already provides an editor and a
7353 <sect id="web-appl">
7354 <heading>Web servers and applications</heading>
7357 This section describes the locations and URLs that should
7358 be used by all web servers and web applications in the
7365 Cgi-bin executable files are installed in the
7367 <example compact="compact">
7368 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
7370 and should be referred to as
7371 <example compact="compact">
7372 http://localhost/cgi-bin/<var>cgi-bin-name</var>
7377 <p>Access to HTML documents</p>
7380 HTML documents for a package are stored in
7381 <file>/usr/share/doc/<var>package</var></file>
7382 and can be referred to as
7383 <example compact="compact">
7384 http://localhost/doc/<var>package</var>/<var>filename</var>
7389 The web server should restrict access to the document
7390 tree so that only clients on the same host can read
7391 the documents. If the web server does not support such
7392 access controls, then it should not provide access at
7393 all, or ask about providing access during installation.
7398 <p>Web Document Root</p>
7401 Web Applications should try to avoid storing files in
7402 the Web Document Root. Instead they should use the
7403 /usr/share/doc/<var>package</var> directory for
7404 documents and register the Web Application via the
7405 menu package. If access to the web document root is
7406 unavoidable then use
7407 <example compact="compact">
7410 as the Document Root. This might be just a symbolic
7411 link to the location where the system administrator
7412 has put the real document root.
7420 <sect id="mail-transport-agents">
7421 <heading>Mail transport, delivery and user agents</heading>
7424 Debian packages which process electronic mail, whether mail
7425 user agents (MUAs) or mail transport agents (MTAs), must
7426 ensure that they are compatible with the configuration
7427 decisions below. Failure to do this may result in lost
7428 mail, broken <tt>From:</tt> lines, and other serious brain
7433 The mail spool is <file>/var/mail</file> and the interface to
7434 send a mail message is <file>/usr/sbin/sendmail</file> (as per
7435 the FHS). On older systems, the mail spool may be
7436 physically located in <file>/var/spool/mail</file>, but all
7437 access to the mail spool should be via the
7438 <file>/var/mail</file> symlink. The mail spool is part of the
7439 base system and not part of the MTA package.
7443 All Debian MUAs, MTAs, MDAs and other mailbox accessing
7444 programs (such as IMAP daemons) must lock the mailbox in an
7445 NFS-safe way. This means that <tt>fcntl()</tt> locking must
7446 be combined with dot locking. To avoid deadlocks, a program
7447 should use <tt>fcntl()</tt> first and dot locking after
7448 this, or alternatively implement the two locking methods in
7449 a non blocking way<footnote>
7450 If it is not possible to establish both locks, the
7451 system shouldn't wait for the second lock to be
7452 established, but remove the first lock, wait a (random)
7453 time, and start over locking again.
7454 </footnote>. Using the functions <tt>maillock</tt> and
7455 <tt>mailunlock</tt> provided by the
7456 <tt>liblockfile*</tt><footnote>
7457 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
7458 to use these functions.
7459 </footnote> packages is the recommended way to realize this.
7463 Mailboxes are generally mode 660
7464 <tt><var>user</var>.mail</tt> unless the system
7465 administrator has chosen otherwise. A MUA may remove a
7466 mailbox (unless it has nonstandard permissions) in which
7467 case the MTA or another MUA must recreate it if needed.
7468 Mailboxes must be writable by group mail.
7472 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
7473 be setgid mail to do the locking mentioned above (and
7474 must obviously avoid accessing other users' mailboxes
7475 using this privilege).</p>
7478 <file>/etc/aliases</file> is the source file for the system mail
7479 aliases (e.g., postmaster, usenet, etc.), it is the one
7480 which the sysadmin and <prgn>postinst</prgn> scripts may
7481 edit. After <file>/etc/aliases</file> is edited the program or
7482 human editing it must call <prgn>newaliases</prgn>. All MTA
7483 packages must come with a <prgn>newaliases</prgn> program,
7484 even if it does nothing, but older MTA packages did not do
7485 this so programs should not fail if <prgn>newaliases</prgn>
7486 cannot be found. Note that because of this, all MTA
7487 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
7488 <tt>Replaces: mail-transport-agent</tt> control file
7493 The convention of writing <tt>forward to
7494 <var>address</var></tt> in the mailbox itself is not
7495 supported. Use a <tt>.forward</tt> file instead.</p>
7498 The <prgn>rmail</prgn> program used by UUCP
7499 for incoming mail should be <file>/usr/sbin/rmail</file>.
7500 Likewise, <prgn>rsmtp</prgn>, for receiving
7501 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
7505 If your package needs to know what hostname to use on (for
7506 example) outgoing news and mail messages which are generated
7507 locally, you should use the file <file>/etc/mailname</file>. It
7508 will contain the portion after the username and <tt>@</tt>
7509 (at) sign for email addresses of users on the machine
7510 (followed by a newline).
7514 Such package should check for the existence of this file
7515 when it is being configured. If it exists, it should be
7516 used without comment, although an MTA's configuration script
7517 may wish to prompt the user even if it finds that this file
7518 exists. If the file does not exist, the package should
7519 prompt the user for the value (preferably using
7520 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
7521 as well as using it in the package's configuration. The
7522 prompt should make it clear that the name will not just be
7523 used by that package. For example, in this situation the
7524 <tt>inn</tt> package could say something like:
7525 <example compact="compact">
7526 Please enter the "mail name" of your system. This is the
7527 hostname portion of the address to be shown on outgoing
7528 news and mail messages. The default is
7529 <var>syshostname</var>, your system's host name. Mail
7530 name ["<var>syshostname</var>"]:
7532 where <var>syshostname</var> is the output of <tt>hostname
7538 <heading>News system configuration</heading>
7541 All the configuration files related to the NNTP (news)
7542 servers and clients should be located under
7543 <file>/etc/news</file>.</p>
7546 There are some configuration issues that apply to a number
7547 of news clients and server packages on the machine. These
7551 <tag><file>/etc/news/organization</file></tag>
7553 A string which should appear as the
7554 organization header for all messages posted
7555 by NNTP clients on the machine
7558 <tag><file>/etc/news/server</file></tag>
7560 Contains the FQDN of the upstream NNTP
7561 server, or localhost if the local machine is
7566 Other global files may be added as required for cross-package news
7573 <heading>Programs for the X Window System</heading>
7576 <heading>Providing X support and package priorities</heading>
7579 Programs that can be configured with support for the X
7580 Window System must be configured to do so and must declare
7581 any package dependencies necessary to satisfy their
7582 runtime requirements when using the X Window System. If
7583 such a package is of higher priority than the X packages
7584 on which it depends, it is required that either the
7585 X-specific components be split into a separate package, or
7586 that an alternative version of the package, which includes
7587 X support, be provided, or that the package's priority be
7593 <heading>Packages providing an X server</heading>
7596 Packages that provide an X server that, directly or
7597 indirectly, communicates with real input and display
7598 hardware should declare in their control data that they
7599 provide the virtual package <tt>xserver</tt>.<footnote>
7600 This implements current practice, and provides an
7601 actual policy for usage of the <tt>xserver</tt>
7602 virtual package which appears in the virtual packages
7603 list. In a nutshell, X servers that interface
7604 directly with the display and input hardware or via
7605 another subsystem (e.g., GGI) should provide
7606 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
7607 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
7613 <heading>Packages providing a terminal emulator</heading>
7616 Packages that provide a terminal emulator for the X Window
7617 System which meet the criteria listed below should declare
7618 in their control data that they provide the virtual
7619 package <tt>x-terminal-emulator</tt>. They should also
7620 register themselves as an alternative for
7621 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
7626 To be an <tt>x-terminal-emulator</tt>, a program must:
7627 <list compact="compact">
7629 Be able to emulate a DEC VT100 terminal, or a
7630 compatible terminal.
7634 Support the command-line option <tt>-e
7635 <var>command</var></tt>, which creates a new
7636 terminal window<footnote>
7637 "New terminal window" does not necessarily mean
7638 a new top-level X window directly parented by
7639 the window manager; it could, if the terminal
7640 emulator application were so coded, be a new
7641 "view" in a multiple-document interface (MDI).
7643 and runs the specified <var>command</var>,
7644 interpreting the entirity of the rest of the command
7645 line as a command to pass straight to exec, in the
7646 manner that <tt>xterm</tt> does.
7650 Support the command-line option <tt>-T
7651 <var>title</var></tt>, which creates a new terminal
7652 window with the window title <var>title</var>.
7659 <heading>Packages providing a window manager</heading>
7662 Packages that provide a window manager should declare in
7663 their control data that they provide the virtual package
7664 <tt>x-window-manager</tt>. They should also register
7665 themselves as an alternative for
7666 <file>/usr/bin/x-window-manager</file>, with a priority
7667 calculated as follows:
7668 <list compact="compact">
7670 Start with a priority of 20.
7674 If the window manager supports the Debian menu
7675 system, add 20 points if this support is available
7676 in the package's default configuration (i.e., no
7677 configuration files belonging to the system or user
7678 have to be edited to activate the feature); if
7679 configuration files must be modified, add only 10
7685 If the window manager complies with <url
7686 id="http://www.freedesktop.org/standards/wm-spec.html"
7687 name="The Window Manager Specification Project">,
7688 written by the <url id="http://www.freedesktop.org/"
7689 name="Free Desktop Group">, add 40 points.
7693 If the window manager permits the X session to be
7694 restarted using a <em>different</em> window manager
7695 (without killing the X server) in its default
7696 configuration, add 10 points; otherwise add none.
7703 <heading>Packages providing fonts</heading>
7706 Packages that provide fonts for the X Window
7708 For the purposes of Debian Policy, a "font for the X
7709 Window System" is one which is accessed via X protocol
7710 requests. Fonts for the Linux console, for PostScript
7711 renderers, or any other purpose, do not fit this
7712 definition. Any tool which makes such fonts available
7713 to the X Window System, however, must abide by this
7716 must do a number of things to ensure that they are both
7717 available without modification of the X or font server
7718 configuration, and that they do not corrupt files used by
7719 other font packages to register information about
7723 Fonts of any type supported by the X Window System
7724 must be in a separate binary package from any
7725 executables, libraries, or documentation (except
7726 that specific to the fonts shipped, such as their
7727 license information). If one or more of the fonts
7728 so packaged are necessary for proper operation of
7729 the package with which they are associated the font
7730 package may be Recommended; if the fonts merely
7731 provide an enhancement, a Suggests relationship may
7732 be used. Packages must not Depend on font
7734 This is because the X server may retrieve fonts
7735 from the local filesystem or over the network
7736 from an X font server; the Debian package system
7737 is empowered to deal only with the local
7743 BDF fonts must be converted to PCF fonts with the
7744 <prgn>bdftopcf</prgn> utility (available in the
7745 <tt>xutils</tt> package, <prgn>gzip</prgn>ped, and
7746 placed in a directory that corresponds to their
7748 <list compact="compact">
7750 100 dpi fonts must be placed in
7751 <file>/usr/X11R6/lib/X11/fonts/100dpi/</file>.
7755 75 dpi fonts must be placed in
7756 <file>/usr/X11R6/lib/X11/fonts/75dpi/</file>.
7760 Character-cell fonts, cursor fonts, and other
7761 low-resolution fonts must be placed in
7762 <file>/usr/X11R6/lib/X11/fonts/misc/</file>.
7768 Speedo fonts must be placed in
7769 <file>/usr/X11R6/lib/X11/fonts/Speedo/</file>.
7773 Type 1 fonts must be placed in
7774 <file>/usr/X11R6/lib/X11/fonts/Type1/</file>. If font
7775 metric files are available, they must be placed here
7780 Subdirectories of <file>/usr/X11R6/lib/X11/fonts/</file>
7781 other than those listed above must be neither
7782 created nor used. (The <file>PEX</file>, <file>CID</file>,
7783 and <file>cyrillic</file> directories are excepted for
7784 historical reasons, but installation of files into
7785 these directories remains discouraged.)
7789 Font packages may, instead of placing files directly
7790 in the X font directories listed above, provide
7791 symbolic links in that font directory pointing to
7792 the files' actual location in the filesystem. Such
7793 a location must comply with the FHS.
7797 Font packages should not contain both 75dpi and
7798 100dpi versions of a font. If both are available,
7799 they should be provided in separate binary packages
7800 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
7801 the names of the packages containing the
7802 corresponding fonts.
7806 Fonts destined for the <file>misc</file> subdirectory
7807 should not be included in the same package as 75dpi
7808 or 100dpi fonts; instead, they should be provided in
7809 a separate package with <tt>-misc</tt> appended to
7814 Font packages must not provide the files
7815 <file>fonts.dir</file>, <file>fonts.alias</file>, or
7816 <file>fonts.scale</file> in a font directory:
7819 <file>fonts.dir</file> files must not be provided at all.
7823 <file>fonts.alias</file> and <file>fonts.scale</file>
7824 files, if needed, should be provided in the
7826 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
7827 where <var>fontdir</var> is the name of the
7829 <file>/usr/X11R6/lib/X11/fonts/</file> where the
7830 package's corresponding fonts are stored
7831 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
7832 <var>package</var> is the name of the package
7833 that provides these fonts, and
7834 <var>extension</var> is either <tt>scale</tt>
7835 or <tt>alias</tt>, whichever corresponds to
7842 Font packages must declare a dependency on
7843 <tt>xutils (>> 4.0.3)</tt> in their control
7848 Font packages that provide one or more
7849 <file>fonts.scale</file> files as described above must
7850 invoke <prgn>update-fonts-scale</prgn> on each
7851 directory into which they installed fonts
7852 <em>before</em> invoking
7853 <prgn>update-fonts-dir</prgn> on that directory.
7854 This invocation must occur in both the
7855 <prgn>postinst</prgn> (for all arguments) and
7856 <prgn>postrm</prgn> (for all arguments except
7857 <tt>upgrade</tt>) scripts.
7861 Font packages that provide one or more
7862 <file>fonts.alias</file> files as described above must
7863 invoke <prgn>update-fonts-alias</prgn> on each
7864 directory into which they installed fonts. This
7865 invocation must occur in both the
7866 <prgn>postinst</prgn> (for all arguments) and
7867 <prgn>postrm</prgn> (for all arguments except
7868 <tt>upgrade</tt>) scripts.
7872 Font packages must invoke
7873 <prgn>update-fonts-dir</prgn> on each directory into
7874 which they installed fonts. This invocation must
7875 occur in both the <prgn>postinst</prgn> (for all
7876 arguments) and <prgn>postrm</prgn> (for all
7877 arguments except <tt>upgrade</tt>) scripts.
7881 Font packages must not provide alias names for the
7882 fonts they include which collide with alias names
7883 already in use by fonts already packaged.
7887 Font packages must not provide fonts with the same
7888 XLFD registry name as another font already packaged.
7895 <heading>Application defaults files</heading>
7898 Application defaults files must be installed in the
7899 directory <file>/etc/X11/app-defaults/</file> (use of a
7900 localized subdirectory of <file>/etc/X11/</file> as described
7901 in the <em>X Toolkit Intrinsics - C Language
7902 Interface</em> manual is also permitted). They must be
7903 registered as <tt>conffile</tt>s or handled as
7904 configuration files. Packages must not provide the
7905 directory <file>/usr/X11R6/lib/X11/app-defaults/</file>.
7909 Customization of programs' X resources may also be
7910 supported with the provision of a file with the same name
7911 as that of the package placed in the
7912 <file>/etc/X11/Xresources/</file> directory, which must
7913 registered as a <tt>conffile</tt> or handled as a
7914 configuration file.<footnote>
7915 Note that this mechanism is not the same as using
7916 app-defaults; app-defaults are tied to the client
7917 binary on the local filesystem, whereas X resources
7918 are stored in the X server and affect all connecting
7921 <em>Important:</em> packages that install files into the
7922 <file>/etc/X11/Xresources/</file> directory must conflict with
7923 <tt>xbase (<< 3.3.2.3a-2)</tt>; if this is not done
7924 it is possible for the installing package to destroy a
7925 previously-existing <file>/etc/X11/Xresources</file> file
7926 which had been customized by the system administrator.
7931 <heading>Installation directory issues</heading>
7934 Packages using the X Window System should not be
7935 configured to install files under the <file>/usr/X11R6/</file>
7936 directory unless they use <prgn>imake</prgn>. The
7937 <file>/usr/X11R6/</file> directory hierarchy should be
7938 regarded as deprecated for all packages except the X
7939 Window System itself, and those which use the
7940 <prgn>imake</prgn> program it provides, in which case the
7941 packages may transition out of the <file>/usr/X11R6/</file>
7942 directory at the maintainer's discretion.<footnote>
7943 <prgn>Imake</prgn>-using programs are exempt because,
7944 as long as they are written correctly, the pathnames
7945 they use to locate resources and install themselves
7946 are derived wholly from the X Window System
7947 configuration. Thus, in the event that the X Window
7948 System moves to <file>/usr/X11R7/</file>,
7949 <file>/usr/X12/</file>, or just plain <file>/usr/</file>, all
7950 that is required for these programs is a recompile
7951 against the corresponding X Window System library
7952 development packages.
7957 Programs that use GNU <prgn>autoconf</prgn> and
7958 <prgn>automake</prgn> are usually easily configured at
7959 compile time to use <file>/usr/</file> instead of
7960 <file>/usr/X11R6/</file>, and this should be done whenever
7961 possible. Configuration files for window managers and
7962 display managers should be placed in a subdirectory of
7963 <file>/etc/X11/</file> corresponding to the package name due
7964 to these programs' tight integration with the mechanisms
7965 of the X Window System. Application-level programs should
7966 use the <file>/etc/</file> directory unless otherwise mandated
7971 The installation of files into subdirectories
7972 of <file>/usr/X11R6/include/X11/</file> and
7973 <file>/usr/X11R6/lib/X11/</file> is permitted but discouraged;
7974 package maintainers should determine if subdirectories of
7975 <file>/usr/lib/</file> and <file>/usr/share/</file> can be used
7976 instead. (The use of symbolic links from the
7977 <file>X11R6</file> directories to other FHS-compliant
7978 locations is encouraged if the program is not easily
7979 configured to look elsewhere for its files.)
7983 Packages must not provide or install files into the directories
7984 <file>/usr/bin/X11/</file>, <file>/usr/include/X11/</file> or
7985 <file>/usr/lib/X11/</file>. Files within a package should,
7986 however, make reference to these directories, rather than
7987 their <tt>X11R6</tt>-named counterparts
7988 <file>/usr/X11R6/bin/</file>, <file>/usr/X11R6/include/X11/</file>
7989 and <file>/usr/X11R6/lib/X11/</file>, if the resources being
7990 referred to have not been moved to other FHS-compliant
7996 <heading>The OSF/Motif and OpenMotif libraries</heading>
7999 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8000 OpenMotif libraries</em><footnote>
8001 OSF/Motif and OpenMotif are collectively referred to as
8002 "Motif" in this policy document.
8004 should be compiled against and tested with LessTif (a free
8005 re-implementation of Motif) instead. If the maintainer
8006 judges that the program or programs do not work
8007 sufficiently well with LessTif to be distributed and
8008 supported, but do so when compiled against Motif, then two
8009 versions of the package should be created; one linked
8010 statically against Motif and with <tt>-smotif</tt>
8011 appended to the package name, and one linked dynamically
8012 against Motif and with <tt>-dmotif</tt> appended to the
8017 Both Motif-linked versions are dependent
8018 upon non-DFSG-compliant software and thus cannot be
8019 uploaded to the <em>main</em> distribution; if the
8020 software is itself DFSG-compliant it may be uploaded to
8021 the <em>contrib</em> distribution. While known existing
8022 versions of Motif permit unlimited redistribution of
8023 binaries linked against the library (whether statically or
8024 dynamically), it is the package maintainer's
8025 responsibility to determine whether this is permitted by
8026 the license of the copy of Motif in his or her possession.
8032 <heading>Perl programs and modules</heading>
8035 Perl programs and modules should follow the current Perl policy.
8039 The Perl policy can be found in the <tt>perl-policy</tt>
8040 files in the <tt>debian-policy</tt> package.
8041 It is also available from the Debian web mirrors at
8042 <tt><url name="/doc/packaging-manuals/perl-policy/"
8043 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>
8044 and from the Debian archive mirrors at
8045 <tt><url name="/doc/package-developer/perl-policy.txt.gz"
8046 id="http://ftp.debian.org/debian/doc/package-developer/perl-policy.txt.gz"></tt>.
8051 <heading>Emacs lisp programs</heading>
8054 Please refer to the "Debian Emacs Policy" for details of how to
8055 package emacs lisp programs.
8059 The Emacs policy is available in
8060 <file>debian-emacs-policy.gz</file> of the
8061 <package>emacsen-common</package> package.
8062 It is also available from the Debian web mirrors at
8063 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8064 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8069 <heading>Games</heading>
8072 The permissions on <file>/var/games</file> are mode 755, owner
8073 <tt>root</tt> and group <tt>root</tt>.
8077 Each game decides on its own security policy.</p>
8080 Games which require protected, privileged access to
8081 high-score files, savegames, etc., may be made
8082 set-<em>group</em>-id (mode 2755) and owned by
8083 <tt>root.games</tt>, and use files and directories with
8084 appropriate permissions (770 <tt>root.games</tt>, for
8085 example). They must not be made
8086 set-<em>user</em>-id, as this causes security problems. (If
8087 an attacker can subvert any set-user-id game they can
8088 overwrite the executable of any other, causing other players
8089 of these games to run a Trojan horse program. With a
8090 set-group-id game the attacker only gets access to less
8091 important game data, and if they can get at the other
8092 players' accounts at all it will take considerably more
8096 Some packages, for example some fortune cookie programs, are
8097 configured by the upstream authors to install with their
8098 data files or other static information made unreadable so
8099 that they can only be accessed through set-id programs
8100 provided. You should not do this in a Debian package: anyone can
8101 download the <file>.deb</file> file and read the data from it,
8102 so there is no point making the files unreadable. Not
8103 making the files unreadable also means that you don't have
8104 to make so many programs set-id, which reduces the risk of a
8108 As described in the FHS, binaries of games should be
8109 installed in the directory <file>/usr/games</file>. This also
8110 applies to games that use the X Window System. Manual pages
8111 for games (X and non-X games) should be installed in
8112 <file>/usr/share/man/man6</file>.</p>
8118 <heading>Documentation</heading>
8121 <heading>Manual pages</heading>
8124 You should install manual pages in <prgn>nroff</prgn> source
8125 form, in appropriate places under <file>/usr/share/man</file>.
8126 You should only use sections 1 to 9 (see the FHS for more
8127 details). You must not install a preformatted "cat page".
8131 Each program, utility, and function should have an
8132 associated manual page included in the same package. It is
8133 suggested that all configuration files also have a manual
8134 page included as well. Manual pages for protocols and other
8135 auxiliary things are optional.
8139 If no manual page is available, this is considered as a bug
8140 and should be reported to the Debian Bug Tracking System (the
8141 maintainer of the package is allowed to write this bug report
8142 themselves, if they so desire). Do not close the bug report
8143 until a proper manpage is available.<footnote>
8144 It is not very hard to write a man page. See the
8145 <url id="http://www.schweikhardt.net/man_page_howto.html"
8146 name="Man-Page-HOWTO">,
8147 <manref name="man" section="7">, the examples
8148 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8149 the helper programs <prgn>help2man</prgn>, or the
8150 directory <file>/usr/share/doc/man-db/examples</file>.
8155 You may forward a complaint about a missing manpage to the
8156 upstream authors, and mark the bug as forwarded in the
8157 Debian bug tracking system. Even though the GNU Project do
8158 not in general consider the lack of a manpage to be a bug,
8159 we do; if they tell you that they don't consider it a bug
8160 you should leave the bug in our bug tracking system open
8165 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8169 If one manpage needs to be accessible via several names it
8170 is better to use a symbolic link than the <file>.so</file>
8171 feature, but there is no need to fiddle with the relevant
8172 parts of the upstream source to change from <file>.so</file> to
8173 symlinks: don't do it unless it's easy. You should not
8174 create hard links in the manual page directories, nor put
8175 absolute filenames in <file>.so</file> directives. The filename
8176 in a <file>.so</file> in a manpage should be relative to the
8177 base of the manpage tree (usually
8178 <file>/usr/share/man</file>). If you do not create any links
8179 (whether symlinks, hard links, or <tt>.so</tt> directives)
8180 in the filesystem to the alternate names of the manpage,
8181 then you should not rely on <prgn>man</prgn> finding your
8182 manpage under those names based solely on the information in
8183 the manpage's header.<footnote>
8184 Supporting this in <prgn>man</prgn> often requires
8185 unreasonable processing time to find a manual page or to
8186 report that none exists, and moves knowledge into man's
8187 database that would be better left in the filesystem.
8188 This support is therefore deprecated and will cease to
8189 be present in the future.
8195 <heading>Info documents</heading>
8198 Info documents should be installed in <file>/usr/share/info</file>.
8199 They should be compressed with <tt>gzip -9</tt>.
8203 Your package should call <prgn>install-info</prgn> to update
8204 the Info <file>dir</file> file in its <prgn>postinst</prgn>
8205 script when called with a <tt>configure</tt> argument, for
8207 <example compact="compact">
8208 install-info --quiet --section Development Development \
8209 /usr/share/info/foobar.info
8213 It is a good idea to specify a section for the location of
8214 your program; this is done with the <tt>--section</tt>
8215 switch. To determine which section to use, you should look
8216 at <file>/usr/share/info/dir</file> on your system and choose the most
8217 relevant (or create a new section if none of the current
8218 sections are relevant). Note that the <tt>--section</tt>
8219 flag takes two arguments; the first is a regular expression
8220 to match (case-insensitively) against an existing section,
8221 the second is used when creating a new one.</p>
8224 You should remove the entries in the <prgn>prerm</prgn>
8225 script when called with a <tt>remove</tt> argument:
8226 <example compact="compact">
8227 install-info --quiet --remove /usr/share/info/foobar.info
8231 If <prgn>install-info</prgn> cannot find a description entry
8232 in the Info file you must supply one. See <manref
8233 name="install-info" section="8"> for details.</p>
8237 <heading>Additional documentation</heading>
8240 Any additional documentation that comes with the package may
8241 be installed at the discretion of the package maintainer.
8242 Text documentation should be installed in the directory
8243 <file>/usr/share/doc/<var>package</var></file>, where
8244 <var>package</var> is the name of the package, and
8245 compressed with <tt>gzip -9</tt> unless it is small.
8249 If a package comes with large amounts of documentation which
8250 many users of the package will not require you should create
8251 a separate binary package to contain it, so that it does not
8252 take up disk space on the machines of users who do not need
8253 or want it installed.</p>
8256 It is often a good idea to put text information files
8257 (<file>README</file>s, changelogs, and so forth) that come with
8258 the source package in <file>/usr/share/doc/<var>package</var></file>
8259 in the binary package. However, you don't need to install
8260 the instructions for building and installing the package, of
8264 Packages must not require the existence of any files in
8265 <file>/usr/share/doc/</file> in order to function
8267 The system administrator should be able to
8268 delete files in <file>/usr/share/doc/</file> without causing
8269 any programs to break.
8271 Any files that are referenced by programs but are also
8272 useful as standalone documentation should be installed under
8273 <file>/usr/share/<var>package</var>/</file> with symbolic links from
8274 <file>/usr/share/doc/<var>package</var></file>.
8278 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8279 link to another directory in <file>/usr/share/doc</file> only if
8280 the two packages both come from the same source and the
8281 first package Depends on the second.
8285 Former Debian releases placed all additional documentation
8286 in <file>/usr/doc/<var>package</var></file>. This has been
8287 changed to <file>/usr/share/doc/<var>package</var></file>,
8288 and packages must not put documentation in the directory
8289 <file>/usr/doc/<var>package</var></file>. <footnote>
8290 At this phase of the transition, we no longer require a
8291 symbolic link in <file>/usr/doc/</file>. At a later point,
8292 policy shall change to make the symbolic links a bug.
8298 <heading>Preferred documentation formats</heading>
8301 The unification of Debian documentation is being carried out
8305 If your package comes with extensive documentation in a
8306 markup format that can be converted to various other formats
8307 you should if possible ship HTML versions in a binary
8308 package, in the directory
8309 <file>/usr/share/doc/<var>appropriate-package</var></file> or
8310 its subdirectories.<footnote>
8311 The rationale: The important thing here is that HTML
8312 docs should be available in <em>some</em> package, not
8313 necessarily in the main binary package.
8318 Other formats such as PostScript may be provided at the
8319 package maintainer's discretion.
8323 <sect id="copyrightfile">
8324 <heading>Copyright information</heading>
8327 Every package must be accompanied by a verbatim copy of its
8328 copyright and distribution license in the file
8329 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
8330 file must neither be compressed nor be a symbolic link.
8334 In addition, the copyright file must say where the upstream
8335 sources (if any) were obtained. It should name the original
8336 authors of the package and the Debian maintainer(s) who were
8337 involved with its creation.</p>
8340 A copy of the file which will be installed in
8341 <file>/usr/share/doc/<var>package</var>/copyright</file> should
8342 be in <file>debian/copyright</file> in the source package.
8346 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8347 link to another directory in <file>/usr/share/doc</file> only if
8348 the two packages both come from the same source and the
8349 first package Depends on the second. These rules are
8350 important because copyrights must be extractable by
8355 Packages distributed under the UCB BSD license, the Artistic
8356 license, the GNU GPL, and the GNU LGPL should refer to the
8357 files <file>/usr/share/common-licenses/BSD</file>,
8358 <file>/usr/share/common-licenses/Artistic</file>,
8359 <file>/usr/share/common-licenses/GPL</file>, and
8360 <file>/usr/share/common-licenses/LGPL</file> respectively,
8361 rather than quoting them in the copyright file.
8365 You should not use the copyright file as a general <file>README</file>
8366 file. If your package has such a file it should be
8367 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
8368 <file>README.Debian</file> or some other appropriate place.</p>
8372 <heading>Examples</heading>
8375 Any examples (configurations, source files, whatever),
8376 should be installed in a directory
8377 <file>/usr/share/doc/<var>package</var>/examples</file>. These
8378 files should not be referenced by any program: they're there
8379 for the benefit of the system administrator and users as
8380 documentation only. Architecture-specific example files
8381 should be installed in a directory
8382 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
8384 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
8385 latter directory itself may be a symbolic link to the
8390 If the purpose of a package is to provide examples, then the
8391 example files may be installed into
8392 <file>/usr/share/doc/<var>package</var></file>.
8396 <sect id="changelogs">
8397 <heading>Changelog files</heading>
8400 Packages that are not Debian-native must contain a
8401 compressed copy of the <file>debian/changelog</file> file from
8402 the Debian source tree in
8403 <file>/usr/share/doc/<var>package</var></file> with the name
8404 <file>changelog.Debian.gz</file>.
8408 If an upstream changelog is available, it should be accessible as
8409 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
8410 plain text. If the upstream changelog is distributed in
8411 HTML, it should be made available in that form as
8412 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
8413 and a plain text <file>changelog.gz</file> should be generated
8414 from it using, for example, <tt>lynx -dump -nolist</tt>. If
8415 the upstream changelog files do not already conform to this
8416 naming convention, then this may be achieved either by
8417 renaming the files, or by adding a symbolic link, at the
8418 maintainer's discretion.<footnote>
8419 Rationale: People should not have to look in places for
8420 upstream changelogs merely because they are given
8421 different names or are distributed in HTML format.
8426 All of these files should be installed compressed using
8427 <tt>gzip -9</tt>, as they will become large with time even
8428 if they start out small.
8432 If the package has only one changelog which is used both as
8433 the Debian changelog and the upstream one because there is
8434 no separate upstream maintainer then that changelog should
8435 usually be installed as
8436 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
8437 there is a separate upstream maintainer, but no upstream
8438 changelog, then the Debian changelog should still be called
8439 <file>changelog.Debian.gz</file>.
8443 For details about the format and contents of the Debian
8444 changelog file, please see <ref id="dpkgchangelog">.
8449 <appendix id="pkg-scope">
8450 <heading>Introduction and scope of these appendices</heading>
8453 These appendices are taken essentially verbatim from the
8454 now-deprecated Packaging Manual, version 3.2.1.0. They are
8455 the chapters which are likely to be of use to package
8456 maintainers and which have not already been included in the
8457 policy document itself. Most of these sections are very likely
8458 not relevant to policy; they should be treated as
8459 documentation for the packaging system. Please note that these
8460 appendices are included for convenience, and for historical
8461 reasons: they used to be part of policy package, and they have
8462 not yet been incorporated into dpkg documentation. However,
8463 they still have value, and hence they are presented here.
8467 They have not yet been checked to ensure that they are
8468 compatible with the contents of policy, and if there are any
8469 contradictions, the version in the main policy document takes
8470 precedence. The remaining chapters of the old Packaging
8471 Manual have also not been read in detail to ensure that there
8472 are not parts which have been left out. Both of these will be
8477 Certain parts of the Packaging manual were integrated into the
8478 Policy Manual proper, and removed from the appendices. Links
8479 have been placed from the old locations to the new ones.
8483 <prgn>dpkg</prgn> is a suite of programs for creating binary
8484 package files and installing and removing them on Unix
8486 <prgn>dpkg</prgn> is targetted primarily at Debian
8487 GNU/Linux, but may work on or be ported to other
8493 The binary packages are designed for the management of
8494 installed executable programs (usually compiled binaries) and
8495 their associated data, though source code examples and
8496 documentation are provided as part of some packages.</p>
8499 This manual describes the technical aspects of creating Debian
8500 binary packages (<file>.deb</file> files). It documents the
8501 behaviour of the package management programs
8502 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
8503 they interact with packages.</p>
8506 It also documents the interaction between
8507 <prgn>dselect</prgn>'s core and the access method scripts it
8508 uses to actually install the selected packages, and describes
8509 how to create a new access method.</p>
8512 This manual does not go into detail about the options and
8513 usage of the package building and installation tools. It
8514 should therefore be read in conjuction with those programs'
8519 The utility programs which are provided with <prgn>dpkg</prgn>
8520 for managing various system configuration and similar issues,
8521 such as <prgn>update-rc.d</prgn> and
8522 <prgn>install-info</prgn>, are not described in detail here -
8523 please see their manpages.
8527 It is assumed that the reader is reasonably familiar with the
8528 <prgn>dpkg</prgn> System Administrators' manual.
8529 Unfortunately this manual does not yet exist.
8533 The Debian version of the FSF's GNU hello program is provided
8534 as an example for people wishing to create Debian
8535 packages. The Debian <prgn>debmake</prgn> package is
8536 recommended as a very helpful tool in creating and maintaining
8537 Debian packages. However, while the tools and examples are
8538 helpful, they do not replace the need to read and follow the
8539 Policy and Programmer's Manual.</p>
8542 <appendix id="pkg-binarypkg">
8543 <heading>Binary packages (from old Packaging Manual)</heading>
8546 The binary package has two main sections. The first part
8547 consists of various control information files and scripts used
8548 by <prgn>dpkg</prgn> when installing and removing. See <ref
8549 id="pkg-controlarea">.
8553 The second part is an archive containing the files and
8554 directories to be installed.
8558 In the future binary packages may also contain other
8559 components, such as checksums and digital signatures. The
8560 format for the archive is described in full in the
8561 <file>deb(5)</file> manpage.
8565 <sect id="pkg-bincreating"><heading>Creating package files -
8566 <prgn>dpkg-deb</prgn>
8570 All manipulation of binary package files is done by
8571 <prgn>dpkg-deb</prgn>; it's the only program that has
8572 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
8573 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
8574 will spot that the options requested are appropriate to
8575 <prgn>dpkg-deb</prgn> and invoke that instead with the same
8580 In order to create a binary package you must make a
8581 directory tree which contains all the files and directories
8582 you want to have in the filesystem data part of the package.
8583 In Debian-format source packages this directory is usually
8584 <file>debian/tmp</file>, relative to the top of the package's
8589 They should have the locations (relative to the root of the
8590 directory tree you're constructing) ownerships and
8591 permissions which you want them to have on the system when
8596 With current versions of <prgn>dpkg</prgn> the uid/username
8597 and gid/groupname mappings for the users and groups being
8598 used should be the same on the system where the package is
8599 built and the one where it is installed.
8603 You need to add one special directory to the root of the
8604 miniature filesystem tree you're creating:
8605 <prgn>DEBIAN</prgn>. It should contain the control
8606 information files, notably the binary package control file
8607 (see <ref id="pkg-controlfile">).
8611 The <prgn>DEBIAN</prgn> directory will not appear in the
8612 filesystem archive of the package, and so won't be installed
8613 by <prgn>dpkg</prgn> when the package is installed.
8617 When you've prepared the package, you should invoke:
8619 dpkg --build <var>directory</var>
8624 This will build the package in
8625 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
8626 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
8627 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
8632 See the manpage <manref name="dpkg-deb" section="8"> for details of how
8633 to examine the contents of this newly-created file. You may find the
8634 output of following commands enlightening:
8636 dpkg-deb --info <var>filename</var>.deb
8637 dpkg-deb --contents <var>filename</var>.deb
8638 dpkg --contents <var>filename</var>.deb
8640 To view the copyright file for a package you could use this command:
8642 dpkg --fsys-tarfile <var>filename</var>.deb | tar xof usr/share/doc/<var>\*</var>copyright | less
8647 <sect id="pkg-controlarea">
8648 <heading>Package control information files</heading>
8651 The control information portion of a binary package is a
8652 collection of files with names known to <prgn>dpkg</prgn>.
8653 It will treat the contents of these files specially - some
8654 of them contain information used by <prgn>dpkg</prgn> when
8655 installing or removing the package; others are scripts which
8656 the package maintainer wants <prgn>dpkg</prgn> to run.
8660 It is possible to put other files in the package control
8661 area, but this is not generally a good idea (though they
8662 will largely be ignored).
8666 Here is a brief list of the control info files supported by
8667 <prgn>dpkg</prgn> and a summary of what they're used for.
8672 <tag><tt>control</tt>
8675 This is the key description file used by
8676 <prgn>dpkg</prgn>. It specifies the package's name
8677 and version, gives its description for the user,
8678 states its relationships with other packages, and so
8679 forth. See <ref id="sourcecontrolfiles"> and
8680 <ref id="binarycontrolfiles">.
8684 It is usually generated automatically from information
8685 in the source package by the
8686 <prgn>dpkg-gencontrol</prgn> program, and with
8687 assistance from <prgn>dpkg-shlibdeps</prgn>.
8688 See <ref id="pkg-sourcetools">.
8692 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
8697 These are exectuable files (usually scripts) which
8698 <prgn>dpkg</prgn> runs during installation, upgrade
8699 and removal of packages. They allow the package to
8700 deal with matters which are particular to that package
8701 or require more complicated processing than that
8702 provided by <prgn>dpkg</prgn>. Details of when and
8703 how they are called are in <ref id="maintainerscripts">.
8707 It is very important to make these scripts idempotent.
8708 See <ref id="idempotency">.
8712 The maintainer scripts are guaranteed to run with a
8713 controlling terminal and can interact with the user.
8714 See <ref id="controllingterminal">.
8718 <tag><tt>conffiles</tt>
8721 This file contains a list of configuration files which
8722 are to be handled automatically by <prgn>dpkg</prgn>
8723 (see <ref id="pkg-conffiles">). Note that not necessarily
8724 every configuration file should be listed here.
8727 <tag><tt>shlibs</tt>
8730 This file contains a list of the shared libraries
8731 supplied by the package, with dependency details for
8732 each. This is used by <prgn>dpkg-shlibdeps</prgn>
8733 when it determines what dependencies are required in a
8734 package control file. The <tt>shlibs</tt> file format
8735 is described on <ref id="shlibs">.
8740 <sect id="pkg-controlfile">
8741 <heading>The main control information file: <tt>control</tt></heading>
8744 The most important control information file used by
8745 <prgn>dpkg</prgn> when it installs a package is
8746 <tt>control</tt>. It contains all the package's "vital
8751 The binary package control files of packages built from
8752 Debian sources are made by a special tool,
8753 <prgn>dpkg-gencontrol</prgn>, which reads
8754 <file>debian/control</file> and <file>debian/changelog</file> to
8755 find the information it needs. See <ref id="pkg-sourcepkg"> for
8760 The fields in binary package control files are listed in
8761 <ref id="binarycontrolfiles">.
8765 A description of the syntax of control files and the purpose
8766 of the fields is available in <ref id="controlfields">.
8771 <heading>Time Stamps</heading>
8774 See <ref id="timestamps">.
8779 <appendix id="pkg-sourcepkg">
8780 <heading>Source packages (from old Packaging Manual) </heading>
8783 The Debian binary packages in the distribution are generated
8784 from Debian sources, which are in a special format to assist
8785 the easy and automatic building of binaries.
8788 <sect id="pkg-sourcetools">
8789 <heading>Tools for processing source packages</heading>
8792 Various tools are provided for manipulating source packages;
8793 they pack and unpack sources and help build of binary
8794 packages and help manage the distribution of new versions.
8798 They are introduced and typical uses described here; see
8799 <manref name="dpkg-source" section="1"> for full
8800 documentation about their arguments and operation.
8804 For examples of how to construct a Debian source package,
8805 and how to use those utilities that are used by Debian
8806 source packages, please see the <prgn>hello</prgn> example
8812 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
8817 This program is frequently used by hand, and is also
8818 called from package-independent automated building scripts
8819 such as <prgn>dpkg-buildpackage</prgn>.
8823 To unpack a package it is typically invoked with
8825 dpkg-source -x <var>.../path/to/filename</var>.dsc
8830 with the <file><var>filename</var>.tar.gz</file> and
8831 <file><var>filename</var>.diff.gz</file> (if applicable) in
8832 the same directory. It unpacks into
8833 <file><var>package</var>-<var>version</var></file>, and if
8835 <file><var>package</var>-<var>version</var>.orig</file>, in
8836 the current directory.
8840 To create a packed source archive it is typically invoked:
8842 dpkg-source -b <var>package</var>-<var>version</var>
8847 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
8848 <file>.diff.gz</file> (if appropriate) in the current
8849 directory. <prgn>dpkg-source</prgn> does not clean the
8850 source tree first - this must be done separately if it is
8855 See also <ref id="pkg-sourcearchives">.</p>
8861 <prgn>dpkg-buildpackage</prgn> - overall package-building
8866 <prgn>dpkg-buildpackage</prgn> is a script which invokes
8867 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
8868 targets <tt>clean</tt>, <tt>build</tt> and
8869 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
8870 <prgn>pgp</prgn> to build a signed source and binary
8875 It is usually invoked by hand from the top level of the
8876 built or unbuilt source directory. It may be invoked with
8877 no arguments; useful arguments include:
8878 <taglist compact="compact">
8879 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
8882 Do not PGP-sign the <tt>.changes</tt> file or the
8883 source package <tt>.dsc</tt> file, respectively.</p>
8885 <tag><tt>-p<var>pgp-command</var></tt></tag>
8888 Invoke <var>pgp-command</var> instead of finding
8889 <tt>pgp</tt> on the <prgn>PATH</prgn>.
8890 <var>pgp-command</var> must behave just like
8891 <prgn>pgp</prgn>.</p>
8893 <tag><tt>-r<var>root-command</var></tt></tag>
8896 When root privilege is required, invoke the command
8897 <var>root-command</var>. <var>root-command</var>
8898 should invoke its first argument as a command, from
8899 the <prgn>PATH</prgn> if necessary, and pass its
8900 second and subsequent arguments to the command it
8901 calls. If no <var>root-command</var> is supplied
8902 then <var>dpkg-buildpackage</var> will take no
8903 special action to gain root privilege, so that for
8904 most packages it will have to be invoked as root to
8907 <tag><tt>-b</tt>, <tt>-B</tt></tag>
8910 Two types of binary-only build and upload - see
8911 <manref name="dpkg-source" section="1">.
8920 <prgn>dpkg-gencontrol</prgn> - generates binary package
8925 This program is usually called from <file>debian/rules</file>
8926 (see <ref id="pkg-sourcetree">) in the top level of the source
8931 This is usually done just before the files and directories in the
8932 temporary directory tree where the package is being built have their
8933 permissions and ownerships set and the package is constructed using
8934 <prgn>dpkg-deb/</prgn>
8936 This is so that the control file which is produced has
8937 the right permissions
8942 <prgn>dpkg-gencontrol</prgn> must be called after all the
8943 files which are to go into the package have been placed in
8944 the temporary build directory, so that its calculation of
8945 the installed size of a package is correct.
8949 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
8950 be run after <prgn>dpkg-shlibdeps</prgn> so that the
8951 variable substitutions created by
8952 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
8957 For a package which generates only one binary package, and
8958 which builds it in <file>debian/tmp</file> relative to the top
8959 of the source package, it is usually sufficient to call
8960 <prgn>dpkg-gencontrol</prgn>.
8964 Sources which build several binaries will typically need
8967 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
8968 </example> The <tt>-P</tt> tells
8969 <prgn>dpkg-gencontrol</prgn> that the package is being
8970 built in a non-default directory, and the <tt>-p</tt>
8971 tells it which package's control file should be generated.
8975 <prgn>dpkg-gencontrol</prgn> also adds information to the
8976 list of files in <file>debian/files</file>, for the benefit of
8977 (for example) a future invocation of
8978 <prgn>dpkg-genchanges</prgn>.</p>
8983 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
8988 This program is usually called from <file>debian/rules</file>
8989 just before <prgn>dpkg-gencontrol</prgn> (see <ref
8990 id="pkg-sourcetree">), in the top level of the source tree.
8994 Its arguments are executables.
8997 In a forthcoming dpkg version,
8998 <prgn>dpkg-shlibdeps</prgn> would be required to be
8999 called on shared libraries as well.
9002 They may be specified either in the locations in the
9003 source tree where they are created or in the locations
9004 in the temporary build tree where they are installed
9005 prior to binary package creation.
9007 </footnote> for which shared library dependencies should
9008 be included in the binary package's control file.
9012 If some of the found shared libraries should only
9013 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9014 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9015 by using the <tt>-d<var>dependency-field</var></tt> option
9016 before those executable(s). (Each <tt>-d</tt> option
9017 takes effect until the next <tt>-d</tt>.)
9021 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9022 output control file to be modified. Instead by default it
9023 adds to the <file>debian/substvars</file> file variable
9024 settings like <tt>shlibs:Depends</tt>. These variable
9025 settings must be referenced in dependency fields in the
9026 appropriate per-binary-package sections of the source
9031 For example, the <prgn>procps</prgn> package generates two
9032 kinds of binaries, simple C binaries like <prgn>ps</prgn>
9033 which require a predependency and full-screen ncurses
9034 binaries like <prgn>top</prgn> which require only a
9035 recommendation. It can say in its <file>debian/rules</file>:
9037 dpkg-shlibdeps -dPre-Depends ps -dRecommends top
9039 and then in its main control file <file>debian/control</file>:
9043 Pre-Depends: ${shlibs:Pre-Depends}
9044 Recommends: ${shlibs:Recommends}
9050 Sources which produce several binary packages with
9051 different shared library dependency requirements can use
9052 the <tt>-p<var>varnameprefix</var></tt> option to override
9053 the default <tt>shlibs:</tt> prefix (one invocation of
9054 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9055 They can thus produce several sets of dependency
9056 variables, each of the form
9057 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9058 which can be referred to in the appropriate parts of the
9059 binary package control files.
9066 <prgn>dpkg-distaddfile</prgn> - adds a file to
9067 <file>debian/files</file>
9071 Some packages' uploads need to include files other than
9072 the source and binary package files.
9076 <prgn>dpkg-distaddfile</prgn> adds a file to the
9077 <file>debian/files</file> file so that it will be included in
9078 the <file>.changes</file> file when
9079 <prgn>dpkg-genchanges</prgn> is run.
9083 It is usually invoked from the <tt>binary</tt> target of
9084 <file>debian/rules</file>:
9086 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9088 The <var>filename</var> is relative to the directory where
9089 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9090 is usually the directory above the top level of the source
9091 tree. The <file>debian/rules</file> target should put the
9092 file there just before or just after calling
9093 <prgn>dpkg-distaddfile</prgn>.
9097 The <var>section</var> and <var>priority</var> are passed
9098 unchanged into the resulting <file>.changes</file> file.
9103 <sect1><heading><prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file> upload
9108 This program is usually called by package-independent
9109 automatic building scripts such as
9110 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9115 It is usually called in the top level of a built source
9116 tree, and when invoked with no arguments will print out a
9117 straightforward <file>.changes</file> file based on the
9118 information in the source package's changelog and control
9119 file and the binary and source packages which should have
9125 <sect1><heading><prgn>dpkg-parsechangelog</prgn> - produces parsed representation of
9130 This program is used internally by
9131 <prgn>dpkg-source</prgn> et al. It may also occasionally
9132 be useful in <file>debian/rules</file> and elsewhere. It
9133 parses a changelog, <file>debian/changelog</file> by default,
9134 and prints a control-file format representation of the
9135 information in it to standard output.
9139 <sect1 id="pkg-dpkgarch"><heading><prgn>dpkg-architecture</prgn> -
9140 information about the build and host system
9144 This program can be used manually, but is also invoked by
9145 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9146 to set environment or make variables which specify the build and
9147 host architecture for the package building process.
9152 <sect id="pkg-sourcetree">
9153 <heading>The Debianised source tree</heading>
9156 The source archive scheme described later is intended to
9157 allow a Debianised source tree with some associated control
9158 information to be reproduced and transported easily. The
9159 Debianised source tree is a version of the original program
9160 with certain files added for the benefit of the
9161 Debianisation process, and with any other changes required
9162 made to the rest of the source code and installation
9167 The extra files created for Debian are in the subdirectory
9168 <file>debian</file> of the top level of the Debianised source
9169 tree. They are described below.
9172 <sect1 id="pkg-debianrules">
9173 <heading><file>debian/rules</file> - the main building script</heading>
9176 See <ref id="debianrules">.
9181 <sect1 id="pkg-dpkgchangelog">
9182 <heading><file>debian/changelog</file></heading>
9185 See <ref id="dpkgchangelog">.
9189 It is recommended that the entire changelog be encoded in the
9190 <url id="http://www.cis.ohio-state.edu/cgi-bin/rfc/rfc2279.html" name="UTF-8">
9192 <url id="http://www.unicode.org/"
9193 name="Unicode">.<footnote>
9195 Support for Unicode, and specifically UTF-8, is
9196 steadily increasing among popular applications in
9197 Debian. For example, in unstable, GNOME 2 has
9198 excellent support (almost level 2) in almost all its
9199 applications; the big remaining one is gnome-terminal,
9200 of which one requires development versions in order to
9201 support UTF-8 (available in Debian experimental now if
9202 you want to play). I think that by the time sarge is
9203 released, UTF-8 support will start to hit critical
9206 I think it is fairly obvious that we need to
9207 eventually transition to UTF-8 for our package
9208 infrastructure; it is really the only sane charset in
9209 an international environment. Now, we can't switch to
9210 using UTF-8 for package control fields and the like
9211 until dpkg has better support, but one thing we can
9212 start doing today is requesting that Debian changelogs
9213 are UTF-8 encoded. At some point in time, we can start
9214 requiring them to do so.
9217 Checking for non-UTF8 characters in a changelog is
9218 trivial. Dump the file through
9219 <example>iconv -f utf-8 -t ucs-4</example>
9220 discard the output, and check the return
9221 value. If there are any characters in the stream
9222 which are invalid UTF-8 sequences, iconv will exit
9223 with an error code; and this will be the case for the
9224 vast majority of other character sets.
9229 <sect2><heading>Defining alternative changelog formats
9233 It is possible to use a different format to the standard
9234 one, by providing a parser for the format you wish to
9239 In order to have <tt>dpkg-parsechangelog</tt> run your
9240 parser, you must include a line within the last 40 lines
9241 of your file matching the Perl regular expression:
9242 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9243 parentheses should be the name of the format. For
9244 example, you might say:
9246 @@@ changelog-format: joebloggs @@@
9248 Changelog format names are non-empty strings of alphanumerics.
9252 If such a line exists then <tt>dpkg-parsechangelog</tt>
9253 will look for the parser as
9254 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9256 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9257 it is an error for it not to find it, or for it not to
9258 be an executable program. The default changelog format
9259 is <tt>dpkg</tt>, and a parser for it is provided with
9260 the <tt>dpkg</tt> package.
9264 The parser will be invoked with the changelog open on
9265 standard input at the start of the file. It should read
9266 the file (it may seek if it wishes) to determine the
9267 information required and return the parsed information
9268 to standard output in the form of a series of control
9269 fields in the standard format. By default it should
9270 return information about only the most recent version in
9271 the changelog; it should accept a
9272 <tt>-v<var>version</var></tt> option to return changes
9273 information from all versions present <em>strictly
9274 after</em> <var>version</var>, and it should then be an
9275 error for <var>version</var> not to be present in the
9281 <list compact="compact">
9282 <item><qref id="f-Source"><tt>Source</tt></qref></item>
9283 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
9284 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
9285 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
9286 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
9287 <item><qref id="f-Date"><tt>Date</tt></qref></item>
9288 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
9293 If several versions are being returned (due to the use
9294 of <tt>-v</tt>), the urgency value should be of the
9295 highest urgency code listed at the start of any of the
9296 versions requested followed by the concatenated
9297 (space-separated) comments from all the versions
9298 requested; the maintainer, version, distribution and
9299 date should always be from the most recent version.
9303 For the format of the <tt>Changes</tt> field see
9304 <ref id="f-Changes">.
9308 If the changelog format which is being parsed always or
9309 almost always leaves a blank line between individual
9310 change notes these blank lines should be stripped out,
9311 so as to make the resulting output compact.
9315 If the changelog format does not contain date or package
9316 name information this information should be omitted from
9317 the output. The parser should not attempt to synthesise
9318 it or find it from other sources.
9322 If the changelog does not have the expected format the
9323 parser should exit with a nonzero exit status, rather
9324 than trying to muddle through and possibly generating
9329 A changelog parser may not interact with the user at
9335 <sect1 id="pkg-srcsubstvars">
9336 <heading><file>debian/substvars</file> and variable substitutions</heading>
9339 See <ref id="substvars">.
9345 <heading><file>debian/files</file></heading>
9348 See <ref id="debianfiles">.
9352 <sect1><heading><file>debian/tmp</file>
9356 This is the canonical temporary location for the
9357 construction of binary packages by the <tt>binary</tt>
9358 target. The directory <file>tmp</file> serves as the root of
9359 the filesystem tree as it is being constructed (for
9360 example, by using the package's upstream makefiles install
9361 targets and redirecting the output there), and it also
9362 contains the <tt>DEBIAN</tt> subdirectory. See <ref
9363 id="pkg-bincreating">.
9367 If several binary packages are generated from the same
9368 source tree it is usual to use several
9369 <file>debian/tmp<var>something</var></file> directories, for
9370 example <file>tmp-a</file> or <file>tmp-doc</file>.
9374 Whatever <file>tmp</file> directories are created and used by
9375 <tt>binary</tt> must of course be removed by the
9376 <tt>clean</tt> target.</p></sect1>
9380 <sect id="pkg-sourcearchives"><heading>Source packages as archives
9384 As it exists on the FTP site, a Debian source package
9385 consists of three related files. You must have the right
9386 versions of all three to be able to use them.
9391 <tag>Debian source control file - <tt>.dsc</tt></tag>
9393 This file is a control file used by <prgn>dpkg-source</prgn>
9394 to extract a source package.
9395 See <ref id="debiansourcecontrolfiles">.
9399 Original source archive -
9401 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
9408 This is a compressed (with <tt>gzip -9</tt>)
9409 <prgn>tar</prgn> file containing the source code from
9410 the upstream authors of the program. The tarfile
9411 unpacks into a directory
9412 <file><var>package</var>-<var>upstream-version</var>.orig</file>,
9413 and does not contain files anywhere other than in
9414 there or in its subdirectories.</p>
9418 Debianisation diff -
9420 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
9426 This is a unified context diff (<tt>diff -u</tt>)
9427 giving the changes which are required to turn the
9428 original source into the Debian source. These changes
9429 may only include editing and creating plain files.
9430 The permissions of files, the targets of symbolic
9431 links and the characteristics of special files or
9432 pipes may not be changed and no files may be removed
9437 All the directories in the diff must exist, except the
9438 <file>debian</file> subdirectory of the top of the source
9439 tree, which will be created by
9440 <prgn>dpkg-source</prgn> if necessary when unpacking.
9444 The <prgn>dpkg-source</prgn> program will
9445 automatically make the <file>debian/rules</file> file
9446 executable (see below).</p></item>
9451 If there is no original source code - for example, if the
9452 package is specially prepared for Debian or the Debian
9453 maintainer is the same as the upstream maintainer - the
9454 format is slightly different: then there is no diff, and the
9456 <file><var>package</var>_<var>version</var>.tar.gz</file> and
9457 contains a directory
9458 <file><var>package</var>-<var>version</var></file>.
9463 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
9466 <tt>dpkg-source -x</tt> is the recommended way to unpack a
9467 Debian source package. However, if it is not available it
9468 is possible to unpack a Debian source archive as follows:
9469 <enumlist compact="compact">
9472 Untar the tarfile, which will create a <file>.orig</file>
9476 <p>Rename the <file>.orig</file> directory to
9477 <file><var>package</var>-<var>version</var></file>.</p>
9481 Create the subdirectory <file>debian</file> at the top of
9482 the source tree.</p>
9484 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
9486 <item><p>Untar the tarfile again if you want a copy of the original
9487 source code alongside the Debianised version.</p>
9492 It is not possible to generate a valid Debian source archive
9493 without using <prgn>dpkg-source</prgn>. In particular,
9494 attempting to use <prgn>diff</prgn> directly to generate the
9495 <file>.diff.gz</file> file will not work.
9499 <heading>Restrictions on objects in source packages</heading>
9502 The source package may not contain any hard links
9504 This is not currently detected when building source
9505 packages, but only when extracting
9509 Hard links may be permitted at some point in the
9510 future, but would require a fair amount of
9512 </footnote>, device special files, sockets or setuid or
9515 Setgid directories are allowed.
9520 The source packaging tools manage the changes between the
9521 original and Debianised source using <prgn>diff</prgn> and
9522 <prgn>patch</prgn>. Turning the original source tree as
9523 included in the <file>.orig.tar.gz</file> into the debianised
9524 source must not involve any changes which cannot be
9525 handled by these tools. Problematic changes which cause
9526 <prgn>dpkg-source</prgn> to halt with an error when
9527 building the source package are:
9528 <list compact="compact">
9529 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
9531 <item><p>Changing the targets of symbolic links.</p>
9533 <item><p>Creating directories, other than <file>debian</file>.</p>
9535 <item><p>Changes to the contents of binary files.</p></item>
9536 </list> Changes which cause <prgn>dpkg-source</prgn> to
9537 print a warning but continue anyway are:
9538 <list compact="compact">
9541 Removing files, directories or symlinks.
9543 Renaming a file is not treated specially - it is
9544 seen as the removal of the old file (which
9545 generates a warning, but is otherwise ignored),
9546 and the creation of the new one.
9552 Changed text files which are missing the usual final
9553 newline (either in the original or the modified
9558 Changes which are not represented, but which are not detected by
9559 <prgn>dpkg-source</prgn>, are:
9560 <list compact="compact">
9561 <item><p>Changing the permissions of files (other than
9562 <file>debian/rules</file>) and directories.</p></item>
9567 The <file>debian</file> directory and <file>debian/rules</file>
9568 are handled specially by <prgn>dpkg-source</prgn> - before
9569 applying the changes it will create the <file>debian</file>
9570 directory, and afterwards it will make
9571 <file>debian/rules</file> world-exectuable.
9577 <appendix id="pkg-controlfields">
9578 <heading>Control files and their fields (from old Packaging Manual)</heading>
9581 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
9582 data in a common format, known as control files. Binary and
9583 source packages have control data as do the <file>.changes</file>
9584 files which control the installation of uploaded files, and
9585 <prgn>dpkg</prgn>'s internal databases are in a similar
9590 <heading>Syntax of control files</heading>
9593 See <ref id="controlsyntax">.
9597 It is important to note that there are several fields which
9598 are optional as far as <prgn>dpkg</prgn> and the related
9599 tools are concerned, but which must appear in every Debian
9600 package, or whose omission may cause problems.
9605 <heading>List of fields</heading>
9608 See <ref id="controlfieldslist">.
9612 This section now contains only the fields that didn't belong
9613 to the Policy manual.
9616 <sect1 id="pkg-f-Filename">
9617 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
9620 These fields in <tt>Packages</tt> files give the
9621 filename(s) of (the parts of) a package in the
9622 distribution directories, relative to the root of the
9623 Debian hierarchy. If the package has been split into
9624 several parts the parts are all listed in order, separated
9629 <sect1 id="pkg-f-Size">
9630 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
9633 These fields in <file>Packages</file> files give the size (in
9634 bytes, expressed in decimal) and MD5 checksum of the
9635 file(s) which make(s) up a binary package in the
9636 distribution. If the package is split into several parts
9637 the values for the parts are listed in order, separated by
9642 <sect1 id="pkg-f-Status">
9643 <heading><tt>Status</tt></heading>
9646 This field in <prgn>dpkg</prgn>'s status file records
9647 whether the user wants a package installed, removed or
9648 left alone, whether it is broken (requiring
9649 reinstallation) or not and what its current state on the
9650 system is. Each of these pieces of information is a
9655 <sect1 id="pkg-f-Config-Version">
9656 <heading><tt>Config-Version</tt></heading>
9659 If a package is not installed or not configured, this
9660 field in <prgn>dpkg</prgn>'s status file records the last
9661 version of the package which was successfully
9666 <sect1 id="pkg-f-Conffiles">
9667 <heading><tt>Conffiles</tt></heading>
9670 This field in <prgn>dpkg</prgn>'s status file contains
9671 information about the automatically-managed configuration
9672 files held by a package. This field should <em>not</em>
9673 appear anywhere in a package!
9678 <heading>Obsolete fields</heading>
9681 These are still recognised by <prgn>dpkg</prgn> but should
9682 not appear anywhere any more.
9684 <taglist compact="compact">
9686 <tag><tt>Revision</tt></tag>
9687 <tag><tt>Package-Revision</tt></tag>
9688 <tag><tt>Package_Revision</tt></tag>
9690 The Debian revision part of the package version was
9691 at one point in a separate control file field. This
9692 field went through several names.
9695 <tag><tt>Recommended</tt></tag>
9696 <item>Old name for <tt>Recommends</tt>.</item>
9698 <tag><tt>Optional</tt></tag>
9699 <item>Old name for <tt>Suggests</tt>.</item>
9701 <tag><tt>Class</tt></tag>
9702 <item>Old name for <tt>Priority</tt>.</item>
9711 <appendix id="pkg-conffiles">
9712 <heading>Configuration file handling (from old Packaging Manual)</heading>
9715 <prgn>dpkg</prgn> can do a certain amount of automatic
9716 handling of package configuration files.
9720 Whether this mechanism is appropriate depends on a number of
9721 factors, but basically there are two approaches to any
9722 particular configuration file.
9726 The easy method is to ship a best-effort configuration in the
9727 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
9728 handle updates. If the user is unlikely to want to edit the
9729 file, but you need them to be able to without losing their
9730 changes, and a new package with a changed version of the file
9731 is only released infrequently, this is a good approach.
9735 The hard method is to build the configuration file from
9736 scratch in the <prgn>postinst</prgn> script, and to take the
9737 responsibility for fixing any mistakes made in earlier
9738 versions of the package automatically. This will be
9739 appropriate if the file is likely to need to be different on
9743 <sect><heading>Automatic handling of configuration files by
9748 A package may contain a control area file called
9749 <tt>conffiles</tt>. This file should be a list of filenames
9750 of configuration files needing automatic handling, separated
9751 by newlines. The filenames should be absolute pathnames,
9752 and the files referred to should actually exist in the
9757 When a package is upgraded <prgn>dpkg</prgn> will process
9758 the configuration files during the configuration stage,
9759 shortly before it runs the package's <prgn>postinst</prgn>
9764 For each file it checks to see whether the version of the
9765 file included in the package is the same as the one that was
9766 included in the last version of the package (the one that is
9767 being upgraded from); it also compares the version currently
9768 installed on the system with the one shipped with the last
9773 If neither the user nor the package maintainer has changed
9774 the file, it is left alone. If one or the other has changed
9775 their version, then the changed version is preferred - i.e.,
9776 if the user edits their file, but the package maintainer
9777 doesn't ship a different version, the user's changes will
9778 stay, silently, but if the maintainer ships a new version
9779 and the user hasn't edited it the new version will be
9780 installed (with an informative message). If both have
9781 changed their version the user is prompted about the problem
9782 and must resolve the differences themselves.
9786 The comparisons are done by calculating the MD5 message
9787 digests of the files, and storing the MD5 of the file as it
9788 was included in the most recent version of the package.
9792 When a package is installed for the first time
9793 <prgn>dpkg</prgn> will install the file that comes with it,
9794 unless that would mean overwriting a file already on the
9799 However, note that <prgn>dpkg</prgn> will <em>not</em>
9800 replace a conffile that was removed by the user (or by a
9801 script). This is necessary because with some programs a
9802 missing file produces an effect hard or impossible to
9803 achieve in another way, so that a missing file needs to be
9804 kept that way if the user did it.
9808 Note that a package should <em>not</em> modify a
9809 <prgn>dpkg</prgn>-handled conffile in its maintainer
9810 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
9811 the user confusing and possibly dangerous options for
9812 conffile update when the package is upgraded.</p>
9815 <sect><heading>Fully-featured maintainer script configuration
9820 For files which contain site-specific information such as
9821 the hostname and networking details and so forth, it is
9822 better to create the file in the package's
9823 <prgn>postinst</prgn> script.
9827 This will typically involve examining the state of the rest
9828 of the system to determine values and other information, and
9829 may involve prompting the user for some information which
9830 can't be obtained some other way.
9834 When using this method there are a couple of important
9835 issues which should be considered:
9839 If you discover a bug in the program which generates the
9840 configuration file, or if the format of the file changes
9841 from one version to the next, you will have to arrange for
9842 the postinst script to do something sensible - usually this
9843 will mean editing the installed configuration file to remove
9844 the problem or change the syntax. You will have to do this
9845 very carefully, since the user may have changed the file,
9846 perhaps to fix the very problem that your script is trying
9847 to deal with - you will have to detect these situations and
9848 deal with them correctly.
9852 If you do go down this route it's probably a good idea to
9853 make the program that generates the configuration file(s) a
9854 separate program in <file>/usr/sbin</file>, by convention called
9855 <file><var>package</var>config</file> and then run that if
9856 appropriate from the post-installation script. The
9857 <tt><var>package</var>config</tt> program should not
9858 unquestioningly overwrite an existing configuration - if its
9859 mode of operation is geared towards setting up a package for
9860 the first time (rather than any arbitrary reconfiguration
9861 later) you should have it check whether the configuration
9862 already exists, and require a <tt>--force</tt> flag to
9863 overwrite it.</p></sect>
9866 <appendix id="pkg-alternatives"><heading>Alternative versions of
9867 an interface - <prgn>update-alternatives</prgn> (from old
9872 When several packages all provide different versions of the
9873 same program or file it is useful to have the system select a
9874 default, but to allow the system administrator to change it
9875 and have their decisions respected.
9879 For example, there are several versions of the <prgn>vi</prgn>
9880 editor, and there is no reason to prevent all of them from
9881 being installed at once, each under their own name
9882 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
9883 Nevertheless it is desirable to have the name <tt>vi</tt>
9884 refer to something, at least by default.
9888 If all the packages involved cooperate, this can be done with
9889 <prgn>update-alternatives</prgn>.
9893 Each package provides its own version under its own name, and
9894 calls <prgn>update-alternatives</prgn> in its postinst to
9895 register its version (and again in its prerm to deregister
9900 See the manpage <manref name="update-alternatives"
9901 section="8"> for details.
9905 If <prgn>update-alternatives</prgn> does not seem appropriate
9906 you may wish to consider using diversions instead.</p>
9909 <appendix id="pkg-diversions"><heading>Diversions - overriding a
9910 package's version of a file (from old Packaging Manual)
9914 It is possible to have <prgn>dpkg</prgn> not overwrite a file
9915 when it reinstalls the package it belongs to, and to have it
9916 put the file from the package somewhere else instead.
9920 This can be used locally to override a package's version of a
9921 file, or by one package to override another's version (or
9922 provide a wrapper for it).
9926 Before deciding to use a diversion, read <ref
9927 id="pkg-alternatives"> to see if you really want a diversion
9928 rather than several alternative versions of a program.
9932 There is a diversion list, which is read by <prgn>dpkg</prgn>,
9933 and updated by a special program <prgn>dpkg-divert</prgn>.
9934 Please see <manref name="dpkg-divert" section="8"> for full
9935 details of its operation.
9939 When a package wishes to divert a file from another, it should
9940 call <prgn>dpkg-divert</prgn> in its preinst to add the
9941 diversion and rename the existing file. For example,
9942 supposing that a <prgn>smailwrapper</prgn> package wishes to
9943 install a wrapper around <file>/usr/sbin/smail</file>:
9945 if [ install = "$1" ]; then
9946 dpkg-divert --package smailwrapper --add --rename \
9947 --divert /usr/sbin/smail.real /usr/sbin/smail
9949 </example> Testing <tt>$1</tt> is necessary so that the script
9950 doesn't try to add the diversion again when
9951 <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
9952 smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
9953 copy of <file>/usr/sbin/smail</file> can bypass the diversion and
9954 get installed as the true version.
9958 The postrm has to do the reverse:
9960 if [ remove = "$1" ]; then
9961 dpkg-divert --package smailwrapper --remove --rename \
9962 --divert /usr/sbin/smail.real /usr/sbin/smail
9968 Do not attempt to divert a file which is vitally important for
9969 the system's operation - when using <prgn>dpkg-divert</prgn>
9970 there is a time, after it has been diverted but before
9971 <prgn>dpkg</prgn> has installed the new version, when the file
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