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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 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, 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><url name="debian-policy"
161 id="http://packages.debian.org/debian-policy"></package>
162 (<httpsite>packages.debian.org</httpsite>
163 <httppath>/debian-policy</httppath>).
167 The current version of this document is also available from
168 the Debian web mirrors at
169 <tt><url name="/doc/debian-policy/"
170 id="http://www.debian.org/doc/debian-policy/"></tt>.
172 <httpsite>www.debian.org</httpsite>
173 <httppath>/doc/debian-policy/</httppath>)
174 Also available from the same directory are several other
175 formats: <file>policy.html.tar.gz</file>
176 (<httppath>/doc/debian-policy/policy.html.tar.gz</httppath>),
177 <file>policy.pdf.gz</file>
178 (<httppath>/doc/debian-policy/policy.pdf.gz</httppath>)
179 and <file>policy.ps.gz</file>
180 (<httppath>/doc/debian-policy/policy.ps.gz</httppath>).
184 The <package>debian-policy</package> package also includes the file
185 <file>upgrading-checklist.txt.gz</file> which indicates policy
186 changes between versions of this document.
191 <heading>Authors and Maintainers</heading>
194 Originally called "Debian GNU/Linux Policy Manual", this
195 manual was initially written in 1996 by Ian Jackson.
196 It was revised on November 27th, 1996 by David A. Morris.
197 Christian Schwarz added new sections on March 15th, 1997,
198 and reworked/restructured it in April-July 1997.
199 Christoph Lameter contributed the "Web Standard".
200 Julian Gilbey largely restructured it in 2001.
204 Since September 1998, the responsibility for the contents of
205 this document lies on the <url name="debian-policy mailing list"
206 id="mailto:debian-policy@lists.debian.org">. Proposals
207 are discussed there and inserted into policy after a certain
208 consensus is established.
209 <!-- insert shameless policy-process plug here eventually -->
210 The actual editing is done by a group of maintainers that have
211 no editorial powers. These are the current maintainers:
214 <item>Julian Gilbey</item>
215 <item>Branden Robinson</item>
216 <item>Josip Rodin</item>
217 <item>Manoj Srivastava</item>
222 While the authors of this document have tried hard to avoid
223 typos and other errors, these do still occur. If you discover
224 an error in this manual or if you want to give any
225 comments, suggestions, or criticisms please send an email to
226 the Debian Policy List,
227 <email>debian-policy@lists.debian.org</email>, or submit a
228 bug report against the <tt>debian-policy</tt> package.
232 Please do not try to reach the individual authors or maintainers
233 of the Policy Manual regarding changes to the Policy.
238 <heading>Related documents</heading>
241 There are several other documents other than this Policy Manual
242 that are necessary to fully understand some Debian policies and
247 The external "sub-policy" documents are referred to in:
248 <list compact="compact">
249 <item><ref id="fhs"></item>
250 <item><ref id="virtual_pkg"></item>
251 <item><ref id="menus"></item>
252 <item><ref id="mime"></item>
253 <item><ref id="perl"></item>
254 <item><ref id="maintscriptprompt"></item>
255 <item><ref id="emacs"></item>
260 In addition to those, which carry the weight of policy, there
261 is the Debian Developer's Reference. This document describes
262 procedures and resources for Debian developers, but it is
263 <em>not</em> normative; rather, it includes things that don't
264 belong in the Policy, such as best practices for developers.
268 The Developer's Reference is available in the
269 <package>developers-reference</package> package.
270 It's also available from the Debian web mirrors at
271 <tt><url name="/doc/developers-reference/"
272 id="http://www.debian.org/doc/developers-reference/"></tt>.
280 <heading>The Debian Archive</heading>
283 The Debian GNU/Linux system is maintained and distributed as a
284 collection of <em>packages</em>. Since there are so many of
285 them (currently well over 15000), they are split into
286 <em>sections</em> and given <em>priorities</em> to simplify
287 the handling of them.
291 The effort of the Debian project is to build a free operating
292 system, but not every package we want to make accessible is
293 <em>free</em> in our sense (see the Debian Free Software
294 Guidelines, below), or may be imported/exported without
295 restrictions. Thus, the archive is split into the distribution
296 areas or categories based on their licenses and other restrictions.
300 The aims of this are:
302 <list compact="compact">
303 <item>to allow us to make as much software available as we can</item>
304 <item>to allow us to encourage everyone to write free software,
306 <item>to allow us to make it easy for people to produce
307 CD-ROMs of our system without violating any licenses,
308 import/export restrictions, or any other laws.</item>
313 The <em>main</em> category forms the
314 <em>Debian GNU/Linux distribution</em>.
318 Packages in the other distribution areas (<tt>contrib</tt>,
319 <tt>non-free</tt>) are not considered to be part of the Debian
320 distribution, although we support their use and provide
321 infrastructure for them (such as our bug-tracking system and
322 mailing lists). This Debian Policy Manual applies to these
327 <heading>The Debian Free Software Guidelines</heading>
329 The Debian Free Software Guidelines (DFSG) form our
330 definition of "free software". These are:
332 <tag>Free Redistribution
335 The license of a Debian component may not restrict any
336 party from selling or giving away the software as a
337 component of an aggregate software distribution
338 containing programs from several different
339 sources. The license may not require a royalty or
340 other fee for such sale.
345 The program must include source code, and must allow
346 distribution in source code as well as compiled form.
351 The license must allow modifications and derived
352 works, and must allow them to be distributed under the
353 same terms as the license of the original software.
355 <tag>Integrity of The Author's Source Code
358 The license may restrict source-code from being
359 distributed in modified form <em>only</em> if the
360 license allows the distribution of "patch files"
361 with the source code for the purpose of modifying the
362 program at build time. The license must explicitly
363 permit distribution of software built from modified
364 source code. The license may require derived works to
365 carry a different name or version number from the
366 original software. (This is a compromise. The Debian
367 Project encourages all authors to not restrict any
368 files, source or binary, from being modified.)
370 <tag>No Discrimination Against Persons or Groups
373 The license must not discriminate against any person
376 <tag>No Discrimination Against Fields of Endeavor
379 The license must not restrict anyone from making use
380 of the program in a specific field of endeavor. For
381 example, it may not restrict the program from being
382 used in a business, or from being used for genetic
385 <tag>Distribution of License
388 The rights attached to the program must apply to all
389 to whom the program is redistributed without the need
390 for execution of an additional license by those
393 <tag>License Must Not Be Specific to Debian
396 The rights attached to the program must not depend on
397 the program's being part of a Debian system. If the
398 program is extracted from Debian and used or
399 distributed without Debian but otherwise within the
400 terms of the program's license, all parties to whom
401 the program is redistributed must have the same
402 rights as those that are granted in conjunction with
405 <tag>License Must Not Contaminate Other Software
408 The license must not place restrictions on other
409 software that is distributed along with the licensed
410 software. For example, the license must not insist
411 that all other programs distributed on the same medium
412 must be free software.
414 <tag>Example Licenses
417 The "GPL," "BSD," and "Artistic" licenses are examples of
418 licenses that we consider <em>free</em>.
425 <heading>Categories</heading>
428 <heading>The main category</heading>
431 Every package in <em>main</em> must comply with the DFSG
432 (Debian Free Software Guidelines).
436 In addition, the packages in <em>main</em>
437 <list compact="compact">
439 must not require a package outside of <em>main</em>
440 for compilation or execution (thus, the package must
441 not declare a "Depends", "Recommends", or
442 "Build-Depends" relationship on a non-<em>main</em>
446 must not be so buggy that we refuse to support them,
450 must meet all policy requirements presented in this
459 <heading>The contrib category</heading>
462 Every package in <em>contrib</em> must comply with the DFSG.
466 In addition, the packages in <em>contrib</em>
467 <list compact="compact">
469 must not be so buggy that we refuse to support them,
473 must meet all policy requirements presented in this
481 Examples of packages which would be included in
482 <em>contrib</em> are:
483 <list compact="compact">
485 free packages which require <em>contrib</em>,
486 <em>non-free</em> packages or packages which are not
487 in our archive at all for compilation or execution,
491 wrapper packages or other sorts of free accessories for
498 <sect1 id="non-free">
499 <heading>The non-free category</heading>
502 Packages must be placed in <em>non-free</em> if they are
503 not compliant with the DFSG or are encumbered by patents
504 or other legal issues that make their distribution
509 In addition, the packages in <em>non-free</em>
510 <list compact="compact">
512 must not be so buggy that we refuse to support them,
516 must meet all policy requirements presented in this
517 manual that it is possible for them to meet.
519 It is possible that there are policy
520 requirements which the package is unable to
521 meet, for example, if the source is
522 unavailable. These situations will need to be
523 handled on a case-by-case basis.
532 <sect id="pkgcopyright">
533 <heading>Copyright considerations</heading>
536 Every package must be accompanied by a verbatim copy of
537 its copyright and distribution license in the file
538 <file>/usr/share/doc/<var>package</var>/copyright</file>
539 (see <ref id="copyrightfile"> for further details).
543 We reserve the right to restrict files from being included
544 anywhere in our archives if
545 <list compact="compact">
547 their use or distribution would break a law,
550 there is an ethical conflict in their distribution or
554 we would have to sign a license for them, or
557 their distribution would conflict with other project
564 Programs whose authors encourage the user to make
565 donations are fine for the main distribution, provided
566 that the authors do not claim that not donating is
567 immoral, unethical, illegal or something similar; in such
568 a case they must go in <em>non-free</em>.
572 Packages whose copyright permission notices (or patent
573 problems) do not even allow redistribution of binaries
574 only, and where no special permission has been obtained,
575 must not be placed on the Debian FTP site and its mirrors
580 Note that under international copyright law (this applies
581 in the United States, too), <em>no</em> distribution or
582 modification of a work is allowed without an explicit
583 notice saying so. Therefore a program without a copyright
584 notice <em>is</em> copyrighted and you may not do anything
585 to it without risking being sued! Likewise if a program
586 has a copyright notice but no statement saying what is
587 permitted then nothing is permitted.
591 Many authors are unaware of the problems that restrictive
592 copyrights (or lack of copyright notices) can cause for
593 the users of their supposedly-free software. It is often
594 worthwhile contacting such authors diplomatically to ask
595 them to modify their license terms. However, this can be a
596 politically difficult thing to do and you should ask for
597 advice on the <tt>debian-legal</tt> mailing list first, as
602 When in doubt about a copyright, send mail to
603 <email>debian-legal@lists.debian.org</email>. Be prepared
604 to provide us with the copyright statement. Software
605 covered by the GPL, public domain software and BSD-like
606 copyrights are safe; be wary of the phrases "commercial
607 use prohibited" and "distribution restricted".
611 <sect id="subsections">
612 <heading>Sections</heading>
615 The packages in the categories <em>main</em>,
616 <em>contrib</em> and <em>non-free</em> are grouped further
617 into <em>sections</em> to simplify handling.
621 The category and section for each package should be
622 specified in the package's <tt>Section</tt> control record
623 (see <ref id="f-Section">). However, the maintainer of the
624 Debian archive may override this selection to ensure the
625 consistency of the Debian distribution. The
626 <tt>Section</tt> field should be of the form:
627 <list compact="compact">
629 <em>section</em> if the package is in the
630 <em>main</em> category,
633 <em>segment/section</em> if the package is in
634 the <em>contrib</em> or <em>non-free</em>
641 The Debian archive maintainers provide the authoritative
642 list of sections. At present, they are:
643 <em>admin</em>, <em>comm</em>,
644 <em>devel</em>, <em>doc</em>,
645 <em>editors</em>, <em>electronics</em>, <em>embedded</em>,
646 <em>games</em>, <em>gnome</em>, <em>graphics</em>,
647 <em>hamradio</em>, <em>interpreters</em>, <em>kde</em>,
648 <em>libs</em>, <em>libdevel</em>, <em>mail</em>,
649 <em>math</em>, <em>misc</em>, <em>net</em>, <em>news</em>,
651 <em>otherosfs</em>, <em>perl</em>, <em>python</em>,
652 <em>science</em>, <em>shells</em>,
653 <em>sound</em>, <em>tex</em>, <em>text</em>,
654 <em>utils</em>, <em>web</em>, <em>x11</em>.
658 <sect id="priorities">
659 <heading>Priorities</heading>
662 Each package should have a <em>priority</em> value, which is
663 included in the package's <em>control record</em>
664 (see <ref id="f-Priority">).
665 This information is used by the Debian package management tools to
666 separate high-priority packages from less-important packages.
670 The following <em>priority levels</em> are recognized by the
671 Debian package management tools.
673 <tag><tt>required</tt></tag>
675 Packages which are necessary for the proper
676 functioning of the system (usually, this means that
677 dpkg functionality depends on these packages).
678 Removing a <tt>required</tt> package may cause your
679 system to become totally broken and you may not even
680 be able to use <prgn>dpkg</prgn> to put things back,
681 so only do so if you know what you are doing. Systems
682 with only the <tt>required</tt> packages are probably
683 unusable, but they do have enough functionality to
684 allow the sysadmin to boot and install more software.
686 <tag><tt>important</tt></tag>
688 Important programs, including those which one would
689 expect to find on any Unix-like system. If the
690 expectation is that an experienced Unix person who
691 found it missing would say "What on earth is going on,
692 where is <prgn>foo</prgn>?", it must be an
693 <tt>important</tt> package.<footnote>
694 This is an important criterion because we are
695 trying to produce, amongst other things, a free
698 Other packages without which the system will not run
699 well or be usable must also have priority
700 <tt>important</tt>. This does
701 <em>not</em> include Emacs, the X Window System, TeX
702 or any other large applications. The
703 <tt>important</tt> packages are just a bare minimum of
704 commonly-expected and necessary tools.
706 <tag><tt>standard</tt></tag>
708 These packages provide a reasonably small but not too
709 limited character-mode system. This is what will be
710 installed by default if the user doesn't select anything
711 else. It doesn't include many large applications.
713 <tag><tt>optional</tt></tag>
715 (In a sense everything that isn't required is
716 optional, but that's not what is meant here.) This is
717 all the software that you might reasonably want to
718 install if you didn't know what it was and don't have
719 specialized requirements. This is a much larger system
720 and includes the X Window System, a full TeX
721 distribution, and many applications. Note that
722 optional packages should not conflict with each other.
724 <tag><tt>extra</tt></tag>
726 This contains all packages that conflict with others
727 with required, important, standard or optional
728 priorities, or are only likely to be useful if you
729 already know what they are or have specialized
736 Packages must not depend on packages with lower priority
737 values (excluding build-time dependencies). In order to
738 ensure this, the priorities of one or more packages may need
747 <heading>Binary packages</heading>
750 The Debian GNU/Linux distribution is based on the Debian
751 package management system, called <prgn>dpkg</prgn>. Thus,
752 all packages in the Debian distribution must be provided
753 in the <tt>.deb</tt> file format.
757 <heading>The package name</heading>
760 Every package must have a name that's unique within the Debian
765 The package name is included in the control field
766 <tt>Package</tt>, the format of which is described
767 in <ref id="f-Package">.
768 The package name is also included as a part of the file name
769 of the <tt>.deb</tt> file.
774 <heading>The version of a package</heading>
777 Every package has a version number recorded in its
778 <tt>Version</tt> control file field, described in
779 <ref id="f-Version">.
783 The package management system imposes an ordering on version
784 numbers, so that it can tell whether packages are being up- or
785 downgraded and so that package system front end applications
786 can tell whether a package it finds available is newer than
787 the one installed on the system. The version number format
788 has the most significant parts (as far as comparison is
789 concerned) at the beginning.
793 If an upstream package has problematic version numbers they
794 should be converted to a sane form for use in the
795 <tt>Version</tt> field.
799 <heading>Version numbers based on dates</heading>
802 In general, Debian packages should use the same version
803 numbers as the upstream sources.
807 However, in some cases where the upstream version number is
808 based on a date (e.g., a development "snapshot" release) the
809 package management system cannot handle these version
810 numbers without epochs. For example, dpkg will consider
811 "96May01" to be greater than "96Dec24".
815 To prevent having to use epochs for every new upstream
816 version, the date based portion of the version number
817 should be changed to the following format in such cases:
818 "19960501", "19961224". It is up to the maintainer whether
819 they want to bother the upstream maintainer to change
820 the version numbers upstream, too.
824 Note that other version formats based on dates which are
825 parsed correctly by the package management system should
826 <em>not</em> be changed.
830 Native Debian packages (i.e., packages which have been
831 written especially for Debian) whose version numbers include
832 dates should always use the "YYYYMMDD" format.
839 <heading>The maintainer of a package</heading>
842 Every package must have a Debian maintainer (the
843 maintainer may be one person or a group of people
844 reachable from a common email address, such as a mailing
845 list). The maintainer is responsible for ensuring that
846 the package is placed in the appropriate distributions.
850 The maintainer must be specified in the
851 <tt>Maintainer</tt> control field with their correct name
852 and a working email address. If one person maintains
853 several packages, they should try to avoid having
854 different forms of their name and email address in
855 the <tt>Maintainer</tt> fields of those packages.
859 The format of the <tt>Maintainer</tt> control field is
860 described in <ref id="f-Maintainer">.
864 If the maintainer of a package quits from the Debian
865 project, "Debian QA Group"
866 <email>packages@qa.debian.org</email> takes over the
867 maintainer-ship of the package until someone else
868 volunteers for that task. These packages are called
869 <em>orphaned packages</em>.<footnote>
870 The detailed procedure for doing this gracefully can
871 be found in the Debian Developer's Reference,
872 see <ref id="related">.
877 <sect id="descriptions">
878 <heading>The description of a package</heading>
881 Every Debian package must have an extended description
882 stored in the appropriate field of the control record.
883 The technical information about the format of the
884 <tt>Description</tt> field is in <ref id="f-Description">.
888 The description should describe the package (the program) to a
889 user (system administrator) who has never met it before so that
890 they have enough information to decide whether they want to
891 install it. This description should not just be copied verbatim
892 from the program's documentation.
896 Put important information first, both in the synopsis and
897 extended description. Sometimes only the first part of the
898 synopsis or of the description will be displayed. You can
899 assume that there will usually be a way to see the whole
900 extended description.
904 The description should also give information about the
905 significant dependencies and conflicts between this package
906 and others, so that the user knows why these dependencies and
907 conflicts have been declared.
911 Instructions for configuring or using the package should
912 not be included (that is what installation scripts,
913 manual pages, info files, etc., are for). Copyright
914 statements and other administrivia should not be included
915 either (that is what the copyright file is for).
918 <sect1 id="synopsis"><heading>The single line synopsis</heading>
921 The single line synopsis should be kept brief - certainly
926 Do not include the package name in the synopsis line. The
927 display software knows how to display this already, and you
928 do not need to state it. Remember that in many situations
929 the user may only see the synopsis line - make it as
930 informative as you can.
935 <sect1 id="extendeddesc"><heading>The extended description</heading>
938 Do not try to continue the single line synopsis into the
939 extended description. This will not work correctly when
940 the full description is displayed, and makes no sense
941 where only the summary (the single line synopsis) is
946 The extended description should describe what the package
947 does and how it relates to the rest of the system (in terms
948 of, for example, which subsystem it is which part of).
952 The description field needs to make sense to anyone, even
953 people who have no idea about any of the things the
954 package deals with.<footnote>
955 The blurb that comes with a program in its
956 announcements and/or <prgn>README</prgn> files is
957 rarely suitable for use in a description. It is
958 usually aimed at people who are already in the
959 community where the package is used.
968 <heading>Dependencies</heading>
971 Every package must specify the dependency information
972 about other packages that are required for the first to
977 For example, a dependency entry must be provided for any
978 shared libraries required by a dynamically-linked executable
983 Packages are not required to declare any dependencies they
984 have on other packages which are marked <tt>Essential</tt>
985 (see below), and should not do so unless they depend on a
986 particular version of that package.<footnote>
988 Essential is defined as the minimal set of functionality
989 that must be available and usable on the system even
990 when packages are in an unconfigured (but unpacked)
991 state. This is needed to avoid unresolvable dependency
992 loops on upgrade. If packages add unnecessary
993 dependencies on packages in this set, the chances that
994 there <strong>will</strong> be an unresolvable
995 dependency loop caused by forcing these Essential
996 packages to be configured first before they need to be
997 is greatly increased. It also increases the chances
998 that frontends will be unable to
999 <strong>calculate</strong> an upgrade path, even if one
1003 Also, it's pretty unlikely that functionality from
1004 Essential shall ever be removed (which is one reason why
1005 care must be taken before adding to the Essential
1006 packages set), but <em>packages</em> have been removed
1007 from the Essential set when the functionality moved to a
1008 different package. So depending on these packages
1009 <em>just in case</em> they stop being essential does way
1010 more harm than good.
1016 Sometimes, a package requires another package to be installed
1017 <em>and</em> configured before it can be installed. In this
1018 case, you must specify a <tt>Pre-Depends</tt> entry for
1023 You should not specify a <tt>Pre-Depends</tt> entry for a
1024 package before this has been discussed on the
1025 <tt>debian-devel</tt> mailing list and a consensus about
1026 doing that has been reached.
1030 The format of the package interrelationship control fields is
1031 described in <ref id="relationships">.
1035 <sect id="virtual_pkg">
1036 <heading>Virtual packages</heading>
1039 Sometimes, there are several packages which offer
1040 more-or-less the same functionality. In this case, it's
1041 useful to define a <em>virtual package</em> whose name
1042 describes that common functionality. (The virtual
1043 packages only exist logically, not physically; that's why
1044 they are called <em>virtual</em>.) The packages with this
1045 particular function will then <em>provide</em> the virtual
1046 package. Thus, any other package requiring that function
1047 can simply depend on the virtual package without having to
1048 specify all possible packages individually.
1052 All packages should use virtual package names where
1053 appropriate, and arrange to create new ones if necessary.
1054 They should not use virtual package names (except privately,
1055 amongst a cooperating group of packages) unless they have
1056 been agreed upon and appear in the list of virtual package
1057 names. (See also <ref id="virtual">)
1061 The latest version of the authoritative list of virtual
1062 package names can be found in the <tt>debian-policy</tt> package.
1063 It is also available from the Debian web mirrors at
1064 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1065 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>.
1069 The procedure for updating the list is described in the preface
1076 <heading>Base system</heading>
1079 The <tt>base system</tt> is a minimum subset of the Debian
1080 GNU/Linux system that is installed before everything else
1081 on a new system. Only very few packages are allowed to form
1082 part of the base system, in order to keep the required disk
1087 The base system consists of all those packages with priority
1088 <tt>required</tt> or <tt>important</tt>. Many of them will
1089 be tagged <tt>essential</tt> (see below).
1094 <heading>Essential packages</heading>
1097 Some packages are tagged <tt>essential</tt> for a system
1098 using the <tt>Essential</tt> control file field.
1099 The format of the <tt>Essential</tt> control field is
1100 described in <ref id="f-Essential">.
1104 Since these packages cannot be easily removed (one has to
1105 specify an extra <em>force option</em> to
1106 <prgn>dpkg</prgn> to do so), this flag must not be used
1107 unless absolutely necessary. A shared library package
1108 must not be tagged <tt>essential</tt>; dependencies will
1109 prevent its premature removal, and we need to be able to
1110 remove it when it has been superseded.
1114 Since dpkg will not prevent upgrading of other packages
1115 while an <tt>essential</tt> package is in an unconfigured
1116 state, all <tt>essential</tt> packages must supply all of
1117 their core functionality even when unconfigured. If the
1118 package cannot satisfy this requirement it must not be
1119 tagged as essential, and any packages depending on this
1120 package must instead have explicit dependency fields as
1125 You must not tag any packages <tt>essential</tt> before
1126 this has been discussed on the <tt>debian-devel</tt>
1127 mailing list and a consensus about doing that has been
1132 <sect id="maintscripts">
1133 <heading>Maintainer Scripts</heading>
1136 The package installation scripts should avoid producing
1137 output which is unnecessary for the user to see and
1138 should rely on <prgn>dpkg</prgn> to stave off boredom on
1139 the part of a user installing many packages. This means,
1140 amongst other things, using the <tt>--quiet</tt> option on
1141 <prgn>install-info</prgn>.
1145 Errors which occur during the execution of an installation
1146 script must be checked and the installation must not
1147 continue after an error.
1151 Note that in general <ref id="scripts"> applies to package
1152 maintainer scripts, too.
1156 You should not use <prgn>dpkg-divert</prgn> on a file
1157 belonging to another package without consulting the
1158 maintainer of that package first.
1162 All packages which supply an instance of a common command
1163 name (or, in general, filename) should generally use
1164 <prgn>update-alternatives</prgn>, so that they may be
1165 installed together. If <prgn>update-alternatives</prgn>
1166 is not used, then each package must use
1167 <tt>Conflicts</tt> to ensure that other packages are
1168 de-installed. (In this case, it may be appropriate to
1169 specify a conflict against earlier versions of something
1170 that previously did not use
1171 <prgn>update-alternatives</prgn>; this is an exception to
1172 the usual rule that versioned conflicts should be
1176 <sect1 id="maintscriptprompt">
1177 <heading>Prompting in maintainer scripts</heading>
1179 Package maintainer scripts may prompt the user if
1180 necessary. Prompting should be done by communicating
1181 through a program, such as <prgn>debconf</prgn>, which
1182 conforms to the Debian Configuration management
1183 specification, version 2 or higher. Prompting the user by
1184 other means, such as by hand<footnote>
1185 From the Jargon file: by hand 2. By extension,
1186 writing code which does something in an explicit or
1187 low-level way for which a presupplied library
1188 (<em>debconf, in this instance</em>) routine ought
1189 to have been available.
1190 </footnote>, is now deprecated.
1194 The Debian Configuration management specification is included
1195 in the <file>debconf_specification</file> files in the
1196 <package>debian-policy</package> package.
1197 It is also available from the Debian web mirrors at
1198 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1199 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>.
1203 Packages which use the Debian Configuration management
1204 specification may contain an additional
1205 <prgn>config</prgn> script and a <tt>templates</tt>
1206 file in their control archive<footnote>
1207 The control.tar.gz inside the .deb.
1208 See <manref name="deb" section="5">.
1210 The <prgn>config</prgn> script might be run before the
1211 <prgn>preinst</prgn> script, and before the package is unpacked
1212 or any of its dependencies or pre-dependencies are satisfied.
1213 Therefore it must work using only the tools present in
1214 <em>essential</em> packages.<footnote>
1215 <package>Debconf</package> or another tool that
1216 implements the Debian Configuration management
1217 specification will also be installed, and any
1218 versioned dependencies on it will be satisfied
1219 before preconfiguration begins.
1224 Packages which use the Debian Configuration management
1225 specification must allow for translation of their messages
1226 by using a gettext-based system such as the one provided by
1227 the <package>po-debconf</package> package.
1231 Packages should try to minimize the amount of prompting
1232 they need to do, and they should ensure that the user
1233 will only ever be asked each question once. This means
1234 that packages should try to use appropriate shared
1235 configuration files (such as <file>/etc/papersize</file> and
1236 <file>/etc/news/server</file>), and shared
1237 <package>debconf</package> variables rather than each
1238 prompting for their own list of required pieces of
1243 It also means that an upgrade should not ask the same
1244 questions again, unless the user has used
1245 <tt>dpkg --purge</tt> to remove the package's configuration.
1246 The answers to configuration questions should be stored in an
1247 appropriate place in <file>/etc</file> so that the user can
1248 modify them, and how this has been done should be
1253 If a package has a vitally important piece of
1254 information to pass to the user (such as "don't run me
1255 as I am, you must edit the following configuration files
1256 first or you risk your system emitting badly-formatted
1257 messages"), it should display this in the
1258 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1259 prompt the user to hit return to acknowledge the
1260 message. Copyright messages do not count as vitally
1261 important (they belong in
1262 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1263 neither do instructions on how to use a program (these
1264 should be in on-line documentation, where all the users
1269 Any necessary prompting should almost always be confined
1270 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1271 script. If it is done in the <prgn>postinst</prgn>, it
1272 should be protected with a conditional so that
1273 unnecessary prompting doesn't happen if a package's
1274 installation fails and the <prgn>postinst</prgn> is
1275 called with <tt>abort-upgrade</tt>,
1276 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1286 <heading>Source packages</heading>
1288 <sect id="standardsversion">
1289 <heading>Standards conformance</heading>
1292 Source packages should specify the most recent version number
1293 of this policy document with which your package complied
1294 when it was last updated.
1298 This information may be used to file bug reports
1299 automatically if your package becomes too much out of date.
1303 The version is specified in the <tt>Standards-Version</tt>
1305 The format of the <tt>Standards-Version</tt> field is
1306 described in <ref id="f-Standards-Version">.
1310 You should regularly, and especially if your package has
1311 become out of date, check for the newest Policy Manual
1312 available and update your package, if necessary. When your
1313 package complies with the new standards you should update the
1314 <tt>Standards-Version</tt> source package field and
1315 release it.<footnote>
1316 See the file <file>upgrading-checklist</file> for
1317 information about policy which has changed between
1318 different versions of this document.
1324 <sect id="pkg-relations">
1325 <heading>Package relationships</heading>
1328 Source packages should specify which binary packages they
1329 require to be installed or not to be installed in order to
1330 build correctly. For example, if building a package
1331 requires a certain compiler, then the compiler should be
1332 specified as a build-time dependency.
1336 It is not necessary to explicitly specify build-time
1337 relationships on a minimal set of packages that are always
1338 needed to compile, link and put in a Debian package a
1339 standard "Hello World!" program written in C or C++. The
1340 required packages are called <em>build-essential</em>, and
1341 an informational list can be found in
1342 <file>/usr/share/doc/build-essential/list</file> (which is
1343 contained in the <tt>build-essential</tt>
1346 <list compact="compact">
1348 This allows maintaining the list separately
1349 from the policy documents (the list does not
1350 need the kind of control that the policy
1354 Having a separate package allows one to install
1355 the build-essential packages on a machine, as
1356 well as allowing other packages such as tasks to
1357 require installation of the build-essential
1358 packages using the depends relation.
1361 The separate package allows bug reports against
1362 the list to be categorized separately from
1363 the policy management process in the BTS.
1370 When specifying the set of build-time dependencies, one
1371 should list only those packages explicitly required by the
1372 build. It is not necessary to list packages which are
1373 required merely because some other package in the list of
1374 build-time dependencies depends on them.<footnote>
1375 The reason for this is that dependencies change, and
1376 you should list all those packages, and <em>only</em>
1377 those packages that <em>you</em> need directly. What
1378 others need is their business. For example, if you
1379 only link against <file>libimlib</file>, you will need to
1380 build-depend on <package>libimlib2-dev</package> but
1381 not against any <tt>libjpeg*</tt> packages, even
1382 though <tt>libimlib2-dev</tt> currently depends on
1383 them: installation of <package>libimlib2-dev</package>
1384 will automatically ensure that all of its run-time
1385 dependencies are satisfied.
1390 If build-time dependencies are specified, it must be
1391 possible to build the package and produce working binaries
1392 on a system with only essential and build-essential
1393 packages installed and also those required to satisfy the
1394 build-time relationships (including any implied
1395 relationships). In particular, this means that version
1396 clauses should be used rigorously in build-time
1397 relationships so that one cannot produce bad or
1398 inconsistently configured packages when the relationships
1399 are properly satisfied.
1403 <ref id="relationships"> explains the technical details.
1408 <heading>Changes to the upstream sources</heading>
1411 If changes to the source code are made that are not
1412 specific to the needs of the Debian system, they should be
1413 sent to the upstream authors in whatever form they prefer
1414 so as to be included in the upstream version of the
1419 If you need to configure the package differently for
1420 Debian or for Linux, and the upstream source doesn't
1421 provide a way to do so, you should add such configuration
1422 facilities (for example, a new <prgn>autoconf</prgn> test
1423 or <tt>#define</tt>) and send the patch to the upstream
1424 authors, with the default set to the way they originally
1425 had it. You can then easily override the default in your
1426 <file>debian/rules</file> or wherever is appropriate.
1430 You should make sure that the <prgn>configure</prgn> utility
1431 detects the correct architecture specification string
1432 (refer to <ref id="arch-spec"> for details).
1436 If you need to edit a <prgn>Makefile</prgn> where GNU-style
1437 <prgn>configure</prgn> scripts are used, you should edit the
1438 <file>.in</file> files rather than editing the
1439 <prgn>Makefile</prgn> directly. This allows the user to
1440 reconfigure the package if necessary. You should
1441 <em>not</em> configure the package and edit the generated
1442 <prgn>Makefile</prgn>! This makes it impossible for someone
1443 else to later reconfigure the package without losing the
1449 <sect id="dpkgchangelog">
1450 <heading>Debian changelog: <file>debian/changelog</file></heading>
1453 Changes in the Debian version of the package should be
1454 briefly explained in the Debian changelog file
1455 <file>debian/changelog</file>.<footnote>
1457 Mistakes in changelogs are usually best rectified by
1458 making a new changelog entry rather than "rewriting
1459 history" by editing old changelog entries.
1462 This includes modifications
1463 made in the Debian package compared to the upstream one
1464 as well as other changes and updates to the package.
1466 Although there is nothing stopping an author who is also
1467 the Debian maintainer from using this changelog for all
1468 their changes, it will have to be renamed if the Debian
1469 and upstream maintainers become different people. In such
1470 a case, however, it might be better to maintain the package
1471 as a non-native package.
1480 The format of the <file>debian/changelog</file> allows the
1481 package building tools to discover which version of the package
1482 is being built and find out other release-specific information.
1486 That format is a series of entries like this:
1488 <example compact="compact">
1489 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1491 [optional blank line(s), stripped]
1493 * <var>change details</var>
1494 <var>more change details</var>
1496 [blank line(s), included in output of dpkg-parsechangelog]
1498 * <var>even more change details</var>
1500 [optional blank line(s), stripped]
1502 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1507 <var>package</var> and <var>version</var> are the source
1508 package name and version number.
1512 <var>distribution(s)</var> lists the distributions where
1513 this version should be installed when it is uploaded - it
1514 is copied to the <tt>Distribution</tt> field in the
1515 <file>.changes</file> file. See <ref id="f-Distribution">.
1519 <var>urgency</var> is the value for the <tt>Urgency</tt>
1520 field in the <file>.changes</file> file for the upload
1521 (see <ref id="f-Urgency">). It is not possible to specify
1522 an urgency containing commas; commas are used to separate
1523 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1524 <prgn>dpkg</prgn> changelog format (though there is
1525 currently only one useful <var>keyword</var>,
1530 The change details may in fact be any series of lines
1531 starting with at least two spaces, but conventionally each
1532 change starts with an asterisk and a separating space and
1533 continuation lines are indented so as to bring them in
1534 line with the start of the text above. Blank lines may be
1535 used here to separate groups of changes, if desired.
1539 If this upload resolves bugs recorded in the Bug Tracking
1540 System (BTS), they may be automatically closed on the
1541 inclusion of this package into the Debian archive by
1542 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1543 in the change details.<footnote>
1544 To be precise, the string should match the following
1545 Perl regular expression:
1547 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1549 Then all of the bug numbers listed will be closed by the
1550 archive maintenance script (<prgn>katie</prgn>), or in
1551 the case of an NMU, marked as fixed.
1553 This information is conveyed via the <tt>Closes</tt> field
1554 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1558 The maintainer name and email address used in the changelog
1559 should be the details of the person uploading <em>this</em>
1560 version. They are <em>not</em> necessarily those of the
1561 usual package maintainer. The information here will be
1562 copied to the <tt>Changed-By</tt> field in the
1563 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1564 and then later used to send an acknowledgement when the
1565 upload has been installed.
1569 The <var>date</var> should be in RFC822 format<footnote>
1570 This is generated by <tt>date -R</tt>.
1571 </footnote>; it should include the time zone specified
1572 numerically, with the time zone name or abbreviation
1573 optionally present as a comment in parentheses.
1577 The first "title" line with the package name should start
1578 at the left hand margin; the "trailer" line with the
1579 maintainer and date details should be preceded by exactly
1580 one space. The maintainer details and the date must be
1581 separated by exactly two spaces.
1585 For more information on placement of the changelog files
1586 within binary packages, please see <ref id="changelogs">.
1589 <sect1><heading>Alternative changelog formats</heading>
1592 In non-experimental packages you must use a format for
1593 <file>debian/changelog</file> which is supported by the most
1594 recent released version of <prgn>dpkg</prgn>.
1598 It is possible to use a format different from the standard
1599 one by providing a changelog parser for the format you wish
1600 to use. The parser must have an API compatible with that
1601 expected by <prgn>dpkg-genchanges</prgn> and
1602 <prgn>dpkg-gencontrol</prgn>, and it must not interact with
1605 If there is general interest in the new format, you should
1606 contact the <package>dpkg</package> maintainer to have the
1607 parser script for it included in the <prgn>dpkg</prgn>
1608 package. (You will need to agree that the parser and its
1609 man page may be distributed under the GNU GPL, just as the rest
1610 of <prgn>dpkg</prgn> is.)
1615 <sect id="dpkgcopyright">
1616 <heading>Copyright: <file>debian/copyright</file></heading>
1618 Every package must be accompanied by a verbatim copy of
1619 its copyright and distribution license in the file
1620 <file>/usr/share/doc/<var>package</var>/copyright</file>
1621 (see <ref id="copyrightfile"> for further details). Also see
1622 <ref id="pkgcopyright"> for further considerations relayed
1623 to copyrights for packages.
1627 <heading>Error trapping in makefiles</heading>
1630 When <prgn>make</prgn> invokes a command in a makefile
1631 (including your package's upstream makefiles and
1632 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1633 means that <prgn>sh</prgn>'s usual bad error handling
1634 properties apply: if you include a miniature script as one
1635 of the commands in your makefile you'll find that if you
1636 don't do anything about it then errors are not detected
1637 and <prgn>make</prgn> will blithely continue after
1642 Every time you put more than one shell command (this
1643 includes using a loop) in a makefile command you
1644 must make sure that errors are trapped. For
1645 simple compound commands, such as changing directory and
1646 then running a program, using <tt>&&</tt> rather
1647 than semicolon as a command separator is sufficient. For
1648 more complex commands including most loops and
1649 conditionals you should include a separate <tt>set -e</tt>
1650 command at the start of every makefile command that's
1651 actually one of these miniature shell scripts.
1655 <sect id="timestamps">
1656 <heading>Time Stamps</heading>
1658 Maintainers should preserve the modification times of the
1659 upstream source files in a package, as far as is reasonably
1661 The rationale is that there is some information conveyed
1662 by knowing the age of the file, for example, you could
1663 recognize that some documentation is very old by looking
1664 at the modification time, so it would be nice if the
1665 modification time of the upstream source would be
1671 <sect id="restrictions">
1672 <heading>Restrictions on objects in source packages</heading>
1675 The source package may not contain any hard links<footnote>
1677 This is not currently detected when building source
1678 packages, but only when extracting
1682 Hard links may be permitted at some point in the
1683 future, but would require a fair amount of
1686 </footnote>, device special files, sockets or setuid or
1687 setgid files.<footnote>
1688 Setgid directories are allowed.
1693 <sect id="debianrules">
1694 <heading>Main building script: <file>debian/rules</file></heading>
1697 This file must be an executable makefile, and contains the
1698 package-specific recipes for compiling the package and
1699 building binary package(s) from the source.
1703 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1704 so that it can be invoked by saying its name rather than
1705 invoking <prgn>make</prgn> explicitly.
1709 Since an interactive <file>debian/rules</file> script makes it
1710 impossible to auto-compile that package and also makes it
1711 hard for other people to reproduce the same binary
1712 package, all <em>required targets</em> MUST be
1713 non-interactive. At a minimum, required targets are the
1714 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1715 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1716 <em>binary-indep</em>, and <em>build</em>. It also follows
1717 that any target that these targets depend on must also be
1722 The targets are as follows (required unless stated otherwise):
1724 <tag><tt>build</tt></tag>
1727 The <tt>build</tt> target should perform all the
1728 configuration and compilation of the package.
1729 If a package has an interactive pre-build
1730 configuration routine, the Debianized source package
1731 must either be built after this has taken place (so
1732 that the binary package can be built without rerunning
1733 the configuration) or the configuration routine
1734 modified to become non-interactive. (The latter is
1735 preferable if there are architecture-specific features
1736 detected by the configuration routine.)
1740 For some packages, notably ones where the same
1741 source tree is compiled in different ways to produce
1742 two binary packages, the <tt>build</tt> target
1743 does not make much sense. For these packages it is
1744 good enough to provide two (or more) targets
1745 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1746 for each of the ways of building the package, and a
1747 <tt>build</tt> target that does nothing. The
1748 <tt>binary</tt> target will have to build the
1749 package in each of the possible ways and make the
1750 binary package out of each.
1754 The <tt>build</tt> target must not do anything
1755 that might require root privilege.
1759 The <tt>build</tt> target may need to run the
1760 <tt>clean</tt> target first - see below.
1764 When a package has a configuration and build routine
1765 which takes a long time, or when the makefiles are
1766 poorly designed, or when <tt>build</tt> needs to
1767 run <tt>clean</tt> first, it is a good idea to
1768 <tt>touch build</tt> when the build process is
1769 complete. This will ensure that if <tt>debian/rules
1770 build</tt> is run again it will not rebuild the whole
1772 Another common way to do this is for <tt>build</tt>
1773 to depend on <prgn>build-stamp</prgn> and to do
1774 nothing else, and for the <prgn>build-stamp</prgn>
1775 target to do the building and to <tt>touch
1776 build-stamp</tt> on completion. This is
1777 especially useful if the build routine creates a
1778 file or directory called <tt>build</tt>; in such a
1779 case, <tt>build</tt> will need to be listed as
1780 a phony target (i.e., as a dependency of the
1781 <tt>.PHONY</tt> target). See the documentation of
1782 <prgn>make</prgn> for more information on phony
1788 <tag><tt>build-arch</tt> (optional),
1789 <tt>build-indep</tt> (optional)
1793 A package may also provide both of the targets
1794 <tt>build-arch</tt> and <tt>build-indep</tt>.
1795 The <tt>build-arch</tt> target, if provided, should
1796 perform all the configuration and compilation required
1797 for producing all architecture-dependant binary packages
1798 (those packages for which the body of the
1799 <tt>Architecture</tt> field in <tt>debian/control</tt>
1800 is not <tt>all</tt>).
1801 Similarly, the <tt>build-indep</tt> target, if
1802 provided, should perform all the configuration and
1803 compilation required for producing all
1804 architecture-independent binary packages
1805 (those packages for which the body of the
1806 <tt>Architecture</tt> field in <tt>debian/control</tt>
1808 The <tt>build</tt> target should depend on those of the
1809 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1810 are provided in the rules file.
1814 If one or both of the targets <tt>build-arch</tt> and
1815 <tt>build-indep</tt> are not provided, then invoking
1816 <file>debian/rules</file> with one of the not-provided
1817 targets as arguments should produce a exit status code
1818 of 2. Usually this is provided automatically by make
1819 if the target is missing.
1823 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1824 must not do anything that might require root privilege.
1828 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1829 <tt>binary-indep</tt>
1833 The <tt>binary</tt> target must be all that is
1834 necessary for the user to build the binary package(s)
1835 produced from this source package. It is
1836 split into two parts: <prgn>binary-arch</prgn> builds
1837 the binary packages which are specific to a particular
1838 architecture, and <tt>binary-indep</tt> builds
1839 those which are not.
1842 <tt>binary</tt> may be (and commonly is) a target with
1843 no commands which simply depends on
1844 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1847 Both <tt>binary-*</tt> targets should depend on the
1848 <tt>build</tt> target, or on the appropriate
1849 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1850 provided, so that the package is built if it has not
1851 been already. It should then create the relevant
1852 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1853 make their control files and <prgn>dpkg-deb</prgn> to
1854 build them and place them in the parent of the top
1859 Both the <tt>binary-arch</tt> and
1860 <tt>binary-indep</tt> targets <em>must</em> exist.
1861 If one of them has nothing to do (which will always be
1862 the case if the source generates only a single binary
1863 package, whether architecture-dependent or not), it
1864 must still exist and must always succeed.
1868 The <tt>binary</tt> targets must be invoked as
1870 The <prgn>fakeroot</prgn> package often allows one
1871 to build a package correctly even without being
1877 <tag><tt>clean</tt></tag>
1880 This must undo any effects that the <tt>build</tt>
1881 and <tt>binary</tt> targets may have had, except
1882 that it should leave alone any output files created in
1883 the parent directory by a run of a <tt>binary</tt>
1888 If a <tt>build</tt> file is touched at the end of
1889 the <tt>build</tt> target, as suggested above, it
1890 should be removed as the first action that
1891 <tt>clean</tt> performs, so that running
1892 <tt>build</tt> again after an interrupted
1893 <tt>clean</tt> doesn't think that everything is
1898 The <tt>clean</tt> target may need to be
1899 invoked as root if <tt>binary</tt> has been
1900 invoked since the last <tt>clean</tt>, or if
1901 <tt>build</tt> has been invoked as root (since
1902 <tt>build</tt> may create directories, for
1907 <tag><tt>get-orig-source</tt> (optional)</tag>
1910 This target fetches the most recent version of the
1911 original source package from a canonical archive site
1912 (via FTP or WWW, for example), does any necessary
1913 rearrangement to turn it into the original source
1914 tar file format described below, and leaves it in the
1919 This target may be invoked in any directory, and
1920 should take care to clean up any temporary files it
1925 This target is optional, but providing it if
1926 possible is a good idea.
1932 The <tt>build</tt>, <tt>binary</tt> and
1933 <tt>clean</tt> targets must be invoked with the current
1934 directory being the package's top-level directory.
1939 Additional targets may exist in <file>debian/rules</file>,
1940 either as published or undocumented interfaces or for the
1941 package's internal use.
1945 The architectures we build on and build for are determined
1946 by <prgn>make</prgn> variables using the utility
1947 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
1948 You can determine the
1949 Debian architecture and the GNU style architecture
1950 specification string for the build machine (the machine type
1951 we are building on) as well as for the host machine (the
1952 machine type we are building for). Here is a list of
1953 supported <prgn>make</prgn> variables:
1954 <list compact="compact">
1956 <tt>DEB_*_ARCH</tt> (the Debian architecture)
1959 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
1960 specification string)
1963 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
1964 <tt>DEB_*_GNU_TYPE</tt>)
1967 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
1968 <tt>DEB_*_GNU_TYPE</tt>)
1970 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
1971 the build machine or <tt>HOST</tt> for specification of the
1976 Backward compatibility can be provided in the rules file
1977 by setting the needed variables to suitable default
1978 values; please refer to the documentation of
1979 <prgn>dpkg-architecture</prgn> for details.
1983 It is important to understand that the <tt>DEB_*_ARCH</tt>
1984 string only determines which Debian architecture we are
1985 building on or for. It should not be used to get the CPU
1986 or system information; the GNU style variables should be
1990 <sect1 id="debianrules-options">
1991 <heading><file>debian/rules</file> and
1992 <tt>DEB_BUILD_OPTIONS</tt></heading>
1995 Supporting the standardized environment variable
1996 <tt>DEB_BUILD_OPTIONS</tt> is recommended. This variable can
1997 contain several flags to change how a package is compiled and
1998 built. Each flag must be in the form <var>flag</var> or
1999 <var>flag</var>=<var>options</var>. If multiple flags are
2000 given, they must be separated by whitespace.<footnote>
2001 Some packages support any delimiter, but whitespace is the
2002 easiest to parse inside a makefile and avoids ambiguity with
2003 flag values that contain commas.
2005 <var>flag</var> must start with a lowercase letter
2006 (<tt>a-z</tt>) and consist only of lowercase letters,
2007 numbers (<tt>0-9</tt>), and the characters
2008 <tt>-</tt> and <tt>_</tt> (hyphen and underscore).
2009 <var>options</var> must not contain whitespace. The same
2010 tag should not be given multiple times with conflicting
2011 values. Package maintainers may assume that
2012 <tt>DEB_BUILD_OPTIONS</tt> will not contain conflicting tags.
2016 The meaning of the following tags has been standardized:
2020 The presence of this tag means that the package should
2021 be compiled with a minimum of optimization. For C
2022 programs, it is best to add <tt>-O0</tt> to
2023 <tt>CFLAGS</tt> (although this is usually the default).
2024 Some programs might fail to build or run at this level
2025 of optimization; it may be necessary to use
2026 <tt>-O1</tt>, for example.
2030 This tag means that the debugging symbols should not be
2031 stripped from the binary during installation, so that
2032 debugging information may be included in the package.
2034 <tag>parallel=n</tag>
2036 This tag means that the package should be built using up
2037 to <tt>n</tt> parallel processes if the package build
2038 system supports this.<footnote>
2039 Packages built with <tt>make</tt> can often implement
2040 this by passing the <tt>-j</tt><var>n</var> option to
2043 If the package build system does not support parallel
2044 builds, this string must be ignored. If the package
2045 build system only supports a lower level of concurrency
2046 than <var>n</var>, the package should be built using as
2047 many parallel processes as the package build system
2048 supports. It is up to the package maintainer to decide
2049 whether the package build times are long enough and the
2050 package build system is robust enough to make supporting
2051 parallel builds worthwhile.
2057 Unknown flags must be ignored by <file>debian/rules</file>.
2061 The following makefile snippet is an example of how one may
2062 implement the build options; you will probably have to
2063 massage this example in order to make it work for your
2065 <example compact="compact">
2068 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
2069 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
2070 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
2071 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
2073 ifneq (,$(filter noopt,$(DEB_BUILD_OPTIONS)))
2078 ifeq (,$(filter nostrip,$(DEB_BUILD_OPTIONS)))
2079 INSTALL_PROGRAM += -s
2081 ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2082 NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2083 MAKEFLAGS += -j$(NUMJOBS)
2090 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2091 <sect id="substvars">
2092 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2095 When <prgn>dpkg-gencontrol</prgn>,
2096 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2097 generate control files they perform variable substitutions
2098 on their output just before writing it. Variable
2099 substitutions have the form <tt>${<var>variable</var>}</tt>.
2100 The optional file <file>debian/substvars</file> contains
2101 variable substitutions to be used; variables can also be set
2102 directly from <file>debian/rules</file> using the <tt>-V</tt>
2103 option to the source packaging commands, and certain
2104 predefined variables are also available.
2108 The <file>debian/substvars</file> file is usually generated and
2109 modified dynamically by <file>debian/rules</file> targets, in
2110 which case it must be removed by the <tt>clean</tt> target.
2114 See <manref name="dpkg-source" section="1"> for full
2115 details about source variable substitutions, including the
2116 format of <file>debian/substvars</file>.</p>
2119 <sect id="debianwatch">
2120 <heading>Optional upstream source location: <file>debian/watch</file></heading>
2123 This is an optional, recommended control file for the
2124 <tt>uscan</tt> utility which defines how to automatically
2125 scan ftp or http sites for newly available updates of the
2126 package. This is used by <url id="
2127 http://dehs.alioth.debian.org/"> and other Debian QA tools
2128 to help with quality control and maintenance of the
2129 distribution as a whole.
2134 <sect id="debianfiles">
2135 <heading>Generated files list: <file>debian/files</file></heading>
2138 This file is not a permanent part of the source tree; it
2139 is used while building packages to record which files are
2140 being generated. <prgn>dpkg-genchanges</prgn> uses it
2141 when it generates a <file>.changes</file> file.
2145 It should not exist in a shipped source package, and so it
2146 (and any backup files or temporary files such as
2147 <file>files.new</file><footnote>
2148 <file>files.new</file> is used as a temporary file by
2149 <prgn>dpkg-gencontrol</prgn> and
2150 <prgn>dpkg-distaddfile</prgn> - they write a new
2151 version of <tt>files</tt> here before renaming it,
2152 to avoid leaving a corrupted copy if an error
2154 </footnote>) should be removed by the
2155 <tt>clean</tt> target. It may also be wise to
2156 ensure a fresh start by emptying or removing it at the
2157 start of the <tt>binary</tt> target.
2161 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2162 package, it adds an entry to <file>debian/files</file> for the
2163 <file>.deb</file> file that will be created when <tt>dpkg-deb
2164 --build</tt> is run for that binary package. So for most
2165 packages all that needs to be done with this file is to
2166 delete it in the <tt>clean</tt> target.
2170 If a package upload includes files besides the source
2171 package and any binary packages whose control files were
2172 made with <prgn>dpkg-gencontrol</prgn> then they should be
2173 placed in the parent of the package's top-level directory
2174 and <prgn>dpkg-distaddfile</prgn> should be called to add
2175 the file to the list in <file>debian/files</file>.</p>
2178 <sect id="embeddedfiles">
2179 <heading>Convenience copies of code</heading>
2182 Some software packages include in their distribution convenience
2183 copies of code from other software packages, generally so that
2184 users compiling from source don't have to download multiple
2185 packages. Debian packages should not make use of these
2186 convenience copies unless the included package is explicitly
2187 intended to be used in this way.<footnote>
2188 For example, parts of the GNU build system work like this.
2190 If the included code is already in the Debian archive in the
2191 form of a library, the Debian packaging should ensure that
2192 binary packages reference the libraries already in Debian and
2193 the convenience copy is not used. If the included code is not
2194 already in Debian, it should be packaged separately as a
2195 prerequisite if possible.
2197 Having multiple copies of the same code in Debian is
2198 inefficient, often creates either static linking or shared
2199 library conflicts, and, most importantly, increases the
2200 difficulty of handling security vulnerabilities in the
2209 <chapt id="controlfields">
2210 <heading>Control files and their fields</heading>
2213 The package management system manipulates data represented in
2214 a common format, known as <em>control data</em>, stored in
2215 <em>control files</em>.
2216 Control files are used for source packages, binary packages and
2217 the <file>.changes</file> files which control the installation
2218 of uploaded files<footnote>
2219 <prgn>dpkg</prgn>'s internal databases are in a similar
2224 <sect id="controlsyntax">
2225 <heading>Syntax of control files</heading>
2228 A control file consists of one or more paragraphs of
2230 The paragraphs are also sometimes referred to as stanzas.
2232 The paragraphs are separated by blank lines. Some control
2233 files allow only one paragraph; others allow several, in
2234 which case each paragraph usually refers to a different
2235 package. (For example, in source packages, the first
2236 paragraph refers to the source package, and later paragraphs
2237 refer to binary packages generated from the source.)
2241 Each paragraph consists of a series of data fields; each
2242 field consists of the field name, followed by a colon and
2243 then the data/value associated with that field. It ends at
2244 the end of the (logical) line. Horizontal whitespace
2245 (spaces and tabs) may occur immediately before or after the
2246 value and is ignored there; it is conventional to put a
2247 single space after the colon. For example, a field might
2249 <example compact="compact">
2252 the field name is <tt>Package</tt> and the field value
2257 Many fields' values may span several lines; in this case
2258 each continuation line must start with a space or a tab.
2259 Any trailing spaces or tabs at the end of individual
2260 lines of a field value are ignored.
2264 In fields where it is specified that lines may not wrap,
2265 only a single line of data is allowed and whitespace is not
2266 significant in a field body. Whitespace must not appear
2267 inside names (of packages, architectures, files or anything
2268 else) or version numbers, or between the characters of
2269 multi-character version relationships.
2273 Field names are not case-sensitive, but it is usual to
2274 capitalize the field names using mixed case as shown below.
2278 Blank lines, or lines consisting only of spaces and tabs,
2279 are not allowed within field values or between fields - that
2280 would mean a new paragraph.
2285 <sect id="sourcecontrolfiles">
2286 <heading>Source package control files -- <file>debian/control</file></heading>
2289 The <file>debian/control</file> file contains the most vital
2290 (and version-independent) information about the source package
2291 and about the binary packages it creates.
2295 The first paragraph of the control file contains information about
2296 the source package in general. The subsequent sets each describe a
2297 binary package that the source tree builds.
2301 The fields in the general paragraph (the first one, for the source
2304 <list compact="compact">
2305 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2306 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2307 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2308 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2309 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2310 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2311 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2312 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2317 The fields in the binary package paragraphs are:
2319 <list compact="compact">
2320 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2321 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2322 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2323 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2324 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2325 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2326 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2327 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2332 The syntax and semantics of the fields are described below.
2338 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2339 generate control files for binary packages (see below), by
2340 <prgn>dpkg-genchanges</prgn> to generate the
2341 <tt>.changes</tt> file to accompany the upload, and by
2342 <prgn>dpkg-source</prgn> when it creates the
2343 <file>.dsc</file> source control file as part of a source
2344 archive. Many fields are permitted to span multiple lines in
2345 <file>debian/control</file> but not in any other control
2346 file. These tools are responsible for removing the line
2347 breaks from such fields when using fields from
2348 <file>debian/control</file> to generate other control files.
2352 The fields here may contain variable references - their
2353 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2354 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2355 when they generate output control files.
2356 See <ref id="substvars"> for details.
2361 <sect id="binarycontrolfiles">
2362 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2365 The <file>DEBIAN/control</file> file contains the most vital
2366 (and version-dependent) information about a binary package.
2370 The fields in this file are:
2372 <list compact="compact">
2373 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2374 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2375 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2376 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2377 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2378 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2379 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2380 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2381 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2382 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2383 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2384 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2389 <sect id="debiansourcecontrolfiles">
2390 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2393 This file contains a series of fields, identified and
2394 separated just like the fields in the control file of
2395 a binary package. The fields are listed below; their
2396 syntax is described above, in <ref id="pkg-controlfields">.
2398 <list compact="compact">
2399 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2400 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2401 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2402 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2403 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2404 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2405 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2406 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2407 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2408 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2409 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2414 The source package control file is generated by
2415 <prgn>dpkg-source</prgn> when it builds the source
2416 archive, from other files in the source package,
2417 described above. When unpacking, it is checked against
2418 the files and directories in the other parts of the
2424 <sect id="debianchangesfiles">
2425 <heading>Debian changes files -- <file>.changes</file></heading>
2428 The .changes files are used by the Debian archive maintenance
2429 software to process updates to packages. They contain one
2430 paragraph which contains information from the
2431 <tt>debian/control</tt> file and other data about the
2432 source package gathered via <tt>debian/changelog</tt>
2433 and <tt>debian/rules</tt>.
2437 The fields in this file are:
2439 <list compact="compact">
2440 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2441 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2442 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2443 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2444 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2445 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2446 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2447 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2448 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2449 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2450 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2451 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2452 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2453 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2458 <sect id="controlfieldslist">
2459 <heading>List of fields</heading>
2461 <sect1 id="f-Source">
2462 <heading><tt>Source</tt></heading>
2465 This field identifies the source package name.
2469 In <file>debian/control</file> or a <file>.dsc</file> file,
2470 this field must contain only the name of the source package.
2474 In a binary package control file or a <file>.changes</file>
2475 file, the source package name may be followed by a version
2476 number in parentheses<footnote>
2477 It is customary to leave a space after the package name
2478 if a version number is specified.
2480 This version number may be omitted (and is, by
2481 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2482 the <tt>Version</tt> field of the binary package in
2483 question. The field itself may be omitted from a binary
2484 package control file when the source package has the same
2485 name and version as the binary package.
2489 <sect1 id="f-Maintainer">
2490 <heading><tt>Maintainer</tt></heading>
2493 The package maintainer's name and email address. The name
2494 should come first, then the email address inside angle
2495 brackets <tt><></tt> (in RFC822 format).
2499 If the maintainer's name contains a full stop then the
2500 whole field will not work directly as an email address due
2501 to a misfeature in the syntax specified in RFC822; a
2502 program using this field as an address must check for this
2503 and correct the problem if necessary (for example by
2504 putting the name in round brackets and moving it to the
2505 end, and bringing the email address forward).
2509 <sect1 id="f-Uploaders">
2510 <heading><tt>Uploaders</tt></heading>
2513 List of the names and email addresses of co-maintainers of
2514 the package, if any. If the package has other maintainers
2515 beside the one named in the
2516 <qref id="f-Maintainer">Maintainer field</qref>, their
2517 names and email addresses should be listed here. The
2518 format is the same as that of the Maintainer tag, and
2519 multiple entries should be comma separated. Currently,
2520 this field is restricted to a single line of data. This
2521 is an optional field.
2524 Any parser that interprets the Uploaders field in
2525 <file>debian/control</file> must permit it to span multiple
2526 lines. Line breaks in an Uploaders field that spans multiple
2527 lines are not significant and the semantics of the field are
2528 the same as if the line breaks had not been present.
2532 <sect1 id="f-Changed-By">
2533 <heading><tt>Changed-By</tt></heading>
2536 The name and email address of the person who changed the
2537 said package. Usually the name of the maintainer.
2538 All the rules for the Maintainer field apply here, too.
2542 <sect1 id="f-Section">
2543 <heading><tt>Section</tt></heading>
2546 This field specifies an application area into which the package
2547 has been classified. See <ref id="subsections">.
2551 When it appears in the <file>debian/control</file> file,
2552 it gives the value for the subfield of the same name in
2553 the <tt>Files</tt> field of the <file>.changes</file> file.
2554 It also gives the default for the same field in the binary
2559 <sect1 id="f-Priority">
2560 <heading><tt>Priority</tt></heading>
2563 This field represents how important that it is that the user
2564 have the package installed. See <ref id="priorities">.
2568 When it appears in the <file>debian/control</file> file,
2569 it gives the value for the subfield of the same name in
2570 the <tt>Files</tt> field of the <file>.changes</file> file.
2571 It also gives the default for the same field in the binary
2576 <sect1 id="f-Package">
2577 <heading><tt>Package</tt></heading>
2580 The name of the binary package.
2584 Package names must consist only of lower case letters
2585 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
2586 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
2587 They must be at least two characters long and must start
2588 with an alphanumeric character.
2592 <sect1 id="f-Architecture">
2593 <heading><tt>Architecture</tt></heading>
2596 Depending on context and the control file used, the
2597 <tt>Architecture</tt> field can include the following sets of
2600 <item>A unique single word identifying a Debian machine
2601 architecture, see <ref id="arch-spec">.
2602 <item><tt>all</tt>, which indicates an
2603 architecture-independent package.
2604 <item><tt>any</tt>, which indicates a package available
2605 for building on any architecture.
2606 <item><tt>source</tt>, which indicates a source package.
2611 In the main <file>debian/control</file> file in the source
2612 package, or in the source package control file
2613 <file>.dsc</file>, one may specify a list of architectures
2614 separated by spaces, or the special values <tt>any</tt> or
2619 Specifying <tt>any</tt> indicates that the source package
2620 isn't dependent on any particular architecture and should
2621 compile fine on any one. The produced binary package(s)
2622 will be specific to whatever the current build architecture
2624 This is the most often used setting, and is recommended
2625 for new packages that aren't <tt>Architecture: all</tt>.
2630 Specifying a list of architectures indicates that the source
2631 will build an architecture-dependent package, and will only
2632 work correctly on the listed architectures.<footnote>
2633 This is a setting used for a minority of cases where the
2634 program is not portable. Generally, it should not be used
2640 In a <file>.changes</file> file, the <tt>Architecture</tt>
2641 field lists the architecture(s) of the package(s)
2642 currently being uploaded. This will be a list; if the
2643 source for the package is also being uploaded, the special
2644 entry <tt>source</tt> is also present.
2648 See <ref id="debianrules"> for information how to get the
2649 architecture for the build process.
2653 <sect1 id="f-Essential">
2654 <heading><tt>Essential</tt></heading>
2657 This is a boolean field which may occur only in the
2658 control file of a binary package or in a per-package fields
2659 paragraph of a main source control data file.
2663 If set to <tt>yes</tt> then the package management system
2664 will refuse to remove the package (upgrading and replacing
2665 it is still possible). The other possible value is <tt>no</tt>,
2666 which is the same as not having the field at all.
2671 <heading>Package interrelationship fields:
2672 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2673 <tt>Recommends</tt>, <tt>Suggests</tt>,
2674 <tt>Breaks</tt>, <tt>Conflicts</tt>,
2675 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2679 These fields describe the package's relationships with
2680 other packages. Their syntax and semantics are described
2681 in <ref id="relationships">.</p>
2684 <sect1 id="f-Standards-Version">
2685 <heading><tt>Standards-Version</tt></heading>
2688 The most recent version of the standards (the policy
2689 manual and associated texts) with which the package
2694 The version number has four components: major and minor
2695 version number and major and minor patch level. When the
2696 standards change in a way that requires every package to
2697 change the major number will be changed. Significant
2698 changes that will require work in many packages will be
2699 signaled by a change to the minor number. The major patch
2700 level will be changed for any change to the meaning of the
2701 standards, however small; the minor patch level will be
2702 changed when only cosmetic, typographical or other edits
2703 are made which neither change the meaning of the document
2704 nor affect the contents of packages.
2708 Thus only the first three components of the policy version
2709 are significant in the <em>Standards-Version</em> control
2710 field, and so either these three components or the all
2711 four components may be specified.<footnote>
2712 In the past, people specified the full version number
2713 in the Standards-Version field, for example "2.3.0.0".
2714 Since minor patch-level changes don't introduce new
2715 policy, it was thought it would be better to relax
2716 policy and only require the first 3 components to be
2717 specified, in this example "2.3.0". All four
2718 components may still be used if someone wishes to do so.
2724 <sect1 id="f-Version">
2725 <heading><tt>Version</tt></heading>
2728 The version number of a package. The format is:
2729 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2733 The three components here are:
2735 <tag><var>epoch</var></tag>
2738 This is a single (generally small) unsigned integer. It
2739 may be omitted, in which case zero is assumed. If it is
2740 omitted then the <var>upstream_version</var> may not
2745 It is provided to allow mistakes in the version numbers
2746 of older versions of a package, and also a package's
2747 previous version numbering schemes, to be left behind.
2751 <tag><var>upstream_version</var></tag>
2754 This is the main part of the version number. It is
2755 usually the version number of the original ("upstream")
2756 package from which the <file>.deb</file> file has been made,
2757 if this is applicable. Usually this will be in the same
2758 format as that specified by the upstream author(s);
2759 however, it may need to be reformatted to fit into the
2760 package management system's format and comparison
2765 The comparison behavior of the package management system
2766 with respect to the <var>upstream_version</var> is
2767 described below. The <var>upstream_version</var>
2768 portion of the version number is mandatory.
2772 The <var>upstream_version</var> may contain only
2773 alphanumerics<footnote>
2774 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2776 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2777 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
2778 tilde) and should start with a digit. If there is no
2779 <var>debian_revision</var> then hyphens are not allowed;
2780 if there is no <var>epoch</var> then colons are not
2785 <tag><var>debian_revision</var></tag>
2788 This part of the version number specifies the version of
2789 the Debian package based on the upstream version. It
2790 may contain only alphanumerics and the characters
2791 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
2792 tilde) and is compared in the same way as the
2793 <var>upstream_version</var> is.
2797 It is optional; if it isn't present then the
2798 <var>upstream_version</var> may not contain a hyphen.
2799 This format represents the case where a piece of
2800 software was written specifically to be turned into a
2801 Debian package, and so there is only one "debianisation"
2802 of it and therefore no revision indication is required.
2806 It is conventional to restart the
2807 <var>debian_revision</var> at <tt>1</tt> each time the
2808 <var>upstream_version</var> is increased.
2812 The package management system will break the version
2813 number apart at the last hyphen in the string (if there
2814 is one) to determine the <var>upstream_version</var> and
2815 <var>debian_revision</var>. The absence of a
2816 <var>debian_revision</var> compares earlier than the
2817 presence of one (but note that the
2818 <var>debian_revision</var> is the least significant part
2819 of the version number).
2826 The <var>upstream_version</var> and <var>debian_revision</var>
2827 parts are compared by the package management system using the
2832 The strings are compared from left to right.
2836 First the initial part of each string consisting entirely of
2837 non-digit characters is determined. These two parts (one of
2838 which may be empty) are compared lexically. If a difference
2839 is found it is returned. The lexical comparison is a
2840 comparison of ASCII values modified so that all the letters
2841 sort earlier than all the non-letters and so that a tilde
2842 sorts before anything, even the end of a part. For example,
2843 the following parts are in sorted order from earliest to
2844 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
2845 <tt>a</tt>.<footnote>
2846 One common use of <tt>~</tt> is for upstream pre-releases.
2847 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
2848 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
2853 Then the initial part of the remainder of each string which
2854 consists entirely of digit characters is determined. The
2855 numerical values of these two parts are compared, and any
2856 difference found is returned as the result of the comparison.
2857 For these purposes an empty string (which can only occur at
2858 the end of one or both version strings being compared) counts
2863 These two steps (comparing and removing initial non-digit
2864 strings and initial digit strings) are repeated until a
2865 difference is found or both strings are exhausted.
2869 Note that the purpose of epochs is to allow us to leave behind
2870 mistakes in version numbering, and to cope with situations
2871 where the version numbering scheme changes. It is
2872 <em>not</em> intended to cope with version numbers containing
2873 strings of letters which the package management system cannot
2874 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
2875 silly orderings (the author of this manual has heard of a
2876 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
2877 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
2878 <tt>2</tt> and so forth).
2882 <sect1 id="f-Description">
2883 <heading><tt>Description</tt></heading>
2886 In a source or binary control file, the <tt>Description</tt>
2887 field contains a description of the binary package, consisting
2888 of two parts, the synopsis or the short description, and the
2889 long description. The field's format is as follows:
2894 Description: <single line synopsis>
2895 <extended description over several lines>
2900 The lines in the extended description can have these formats:
2906 Those starting with a single space are part of a paragraph.
2907 Successive lines of this form will be word-wrapped when
2908 displayed. The leading space will usually be stripped off.
2912 Those starting with two or more spaces. These will be
2913 displayed verbatim. If the display cannot be panned
2914 horizontally, the displaying program will line wrap them "hard"
2915 (i.e., without taking account of word breaks). If it can they
2916 will be allowed to trail off to the right. None, one or two
2917 initial spaces may be deleted, but the number of spaces
2918 deleted from each line will be the same (so that you can have
2919 indenting work correctly, for example).
2923 Those containing a single space followed by a single full stop
2924 character. These are rendered as blank lines. This is the
2925 <em>only</em> way to get a blank line<footnote>
2926 Completely empty lines will not be rendered as blank lines.
2927 Instead, they will cause the parser to think you're starting
2928 a whole new record in the control file, and will therefore
2929 likely abort with an error.
2934 Those containing a space, a full stop and some more characters.
2935 These are for future expansion. Do not use them.
2941 Do not use tab characters. Their effect is not predictable.
2945 See <ref id="descriptions"> for further information on this.
2949 In a <file>.changes</file> file, the <tt>Description</tt> field
2950 contains a summary of the descriptions for the packages being
2955 The part of the field before the first newline is empty;
2956 thereafter each line has the name of a binary package and
2957 the summary description line from that binary package.
2958 Each line is indented by one space.
2963 <sect1 id="f-Distribution">
2964 <heading><tt>Distribution</tt></heading>
2967 In a <file>.changes</file> file or parsed changelog output
2968 this contains the (space-separated) name(s) of the
2969 distribution(s) where this version of the package should
2970 be installed. Valid distributions are determined by the
2971 archive maintainers.<footnote>
2972 Current distribution names are:
2973 <taglist compact="compact">
2974 <tag><em>stable</em></tag>
2976 This is the current "released" version of Debian
2977 GNU/Linux. Once the distribution is
2978 <em>stable</em> only security fixes and other
2979 major bug fixes are allowed. When changes are
2980 made to this distribution, the release number is
2981 increased (for example: 2.2r1 becomes 2.2r2 then
2985 <tag><em>unstable</em></tag>
2987 This distribution value refers to the
2988 <em>developmental</em> part of the Debian
2989 distribution tree. New packages, new upstream
2990 versions of packages and bug fixes go into the
2991 <em>unstable</em> directory tree. Download from
2992 this distribution at your own risk.
2995 <tag><em>testing</em></tag>
2997 This distribution value refers to the
2998 <em>testing</em> part of the Debian distribution
2999 tree. It receives its packages from the
3000 unstable distribution after a short time lag to
3001 ensure that there are no major issues with the
3002 unstable packages. It is less prone to breakage
3003 than unstable, but still risky. It is not
3004 possible to upload packages directly to
3008 <tag><em>frozen</em></tag>
3010 From time to time, the <em>testing</em>
3011 distribution enters a state of "code-freeze" in
3012 anticipation of release as a <em>stable</em>
3013 version. During this period of testing only
3014 fixes for existing or newly-discovered bugs will
3015 be allowed. The exact details of this stage are
3016 determined by the Release Manager.
3019 <tag><em>experimental</em></tag>
3021 The packages with this distribution value are
3022 deemed by their maintainers to be high
3023 risk. Oftentimes they represent early beta or
3024 developmental packages from various sources that
3025 the maintainers want people to try, but are not
3026 ready to be a part of the other parts of the
3027 Debian distribution tree. Download at your own
3033 You should list <em>all</em> distributions that the
3034 package should be installed into.
3038 More information is available in the Debian Developer's
3039 Reference, section "The Debian archive".
3046 <heading><tt>Date</tt></heading>
3049 This field includes the date the package was built or last edited.
3053 The value of this field is usually extracted from the
3054 <file>debian/changelog</file> file - see
3055 <ref id="dpkgchangelog">).
3059 <sect1 id="f-Format">
3060 <heading><tt>Format</tt></heading>
3063 This field specifies a format revision for the file.
3064 The most current format described in the Policy Manual
3065 is version <strong>1.5</strong>. The syntax of the
3066 format value is the same as that of a package version
3067 number except that no epoch or Debian revision is allowed
3068 - see <ref id="f-Version">.
3072 <sect1 id="f-Urgency">
3073 <heading><tt>Urgency</tt></heading>
3076 This is a description of how important it is to upgrade to
3077 this version from previous ones. It consists of a single
3078 keyword taking one of the values <tt>low</tt>,
3079 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3080 <tt>critical</tt><footnote>
3081 Other urgency values are supported with configuration
3082 changes in the archive software but are not used in Debian.
3083 The urgency affects how quickly a package will be considered
3084 for inclusion into the <tt>testing</tt> distribution and
3085 gives an indication of the importance of any fixes included
3086 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3087 treated as synonymous.
3088 </footnote> (not case-sensitive) followed by an optional
3089 commentary (separated by a space) which is usually in
3090 parentheses. For example:
3093 Urgency: low (HIGH for users of diversions)
3099 The value of this field is usually extracted from the
3100 <file>debian/changelog</file> file - see
3101 <ref id="dpkgchangelog">.
3105 <sect1 id="f-Changes">
3106 <heading><tt>Changes</tt></heading>
3109 This field contains the human-readable changes data, describing
3110 the differences between the last version and the current one.
3114 There should be nothing in this field before the first
3115 newline; all the subsequent lines must be indented by at
3116 least one space; blank lines must be represented by a line
3117 consisting only of a space and a full stop.
3121 The value of this field is usually extracted from the
3122 <file>debian/changelog</file> file - see
3123 <ref id="dpkgchangelog">).
3127 Each version's change information should be preceded by a
3128 "title" line giving at least the version, distribution(s)
3129 and urgency, in a human-readable way.
3133 If data from several versions is being returned the entry
3134 for the most recent version should be returned first, and
3135 entries should be separated by the representation of a
3136 blank line (the "title" line may also be followed by the
3137 representation of blank line).
3141 <sect1 id="f-Binary">
3142 <heading><tt>Binary</tt></heading>
3145 This field is a list of binary packages.
3149 When it appears in the <file>.dsc</file> file it is the list
3150 of binary packages which a source package can produce. It
3151 does not necessarily produce all of these binary packages
3152 for every architecture. The source control file doesn't
3153 contain details of which architectures are appropriate for
3154 which of the binary packages.
3158 When it appears in a <file>.changes</file> file it lists the
3159 names of the binary packages actually being uploaded.
3163 The syntax is a list of binary packages separated by
3165 A space after each comma is conventional.
3166 </footnote>. Currently the packages must be separated using
3167 only spaces in the <file>.changes</file> file.
3171 <sect1 id="f-Installed-Size">
3172 <heading><tt>Installed-Size</tt></heading>
3175 This field appears in the control files of binary
3176 packages, and in the <file>Packages</file> files. It gives
3177 the total amount of disk space required to install the
3182 The disk space is represented in kilobytes as a simple
3187 <sect1 id="f-Files">
3188 <heading><tt>Files</tt></heading>
3191 This field contains a list of files with information about
3192 each one. The exact information and syntax varies with
3193 the context. In all cases the part of the field
3194 contents on the same line as the field name is empty. The
3195 remainder of the field is one line per file, each line
3196 being indented by one space and containing a number of
3197 sub-fields separated by spaces.
3201 In the <file>.dsc</file> file, each line contains the MD5
3202 checksum, size and filename of the tar file and (if applicable)
3203 diff file which make up the remainder of the source
3205 That is, the parts which are not the <tt>.dsc</tt>.
3207 The exact forms of the filenames are described
3208 in <ref id="pkg-sourcearchives">.
3212 In the <file>.changes</file> file this contains one line per
3213 file being uploaded. Each line contains the MD5 checksum,
3214 size, section and priority and the filename.
3215 The <qref id="f-Section">section</qref>
3216 and <qref id="f-Priority">priority</qref>
3217 are the values of the corresponding fields in
3218 the main source control file. If no section or priority is
3219 specified then <tt>-</tt> should be used, though section
3220 and priority values must be specified for new packages to
3221 be installed properly.
3225 The special value <tt>byhand</tt> for the section in a
3226 <tt>.changes</tt> file indicates that the file in question
3227 is not an ordinary package file and must by installed by
3228 hand by the distribution maintainers. If the section is
3229 <tt>byhand</tt> the priority should be <tt>-</tt>.
3233 If a new Debian revision of a package is being shipped and
3234 no new original source archive is being distributed the
3235 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3236 entry for the original source archive
3237 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
3238 but the <file>.changes</file> file should leave it out. In
3239 this case the original source archive on the distribution
3240 site must match exactly, byte-for-byte, the original
3241 source archive which was used to generate the
3242 <file>.dsc</file> file and diff which are being uploaded.</p>
3245 <sect1 id="f-Closes">
3246 <heading><tt>Closes</tt></heading>
3249 A space-separated list of bug report numbers that the upload
3250 governed by the .changes file closes.
3254 <sect1 id="f-Homepage">
3255 <heading><tt>Homepage</tt></heading>
3258 The URL of the web site for this package, preferably (when
3259 applicable) the site from which the original source can be
3260 obtained and any additional upstream documentation or
3261 information may be found. The content of this field is a
3262 simple URL without any surrounding characters such as
3270 <heading>User-defined fields</heading>
3273 Additional user-defined fields may be added to the
3274 source package control file. Such fields will be
3275 ignored, and not copied to (for example) binary or
3276 source package control files or upload control files.
3280 If you wish to add additional unsupported fields to
3281 these output files you should use the mechanism
3286 Fields in the main source control information file with
3287 names starting <tt>X</tt>, followed by one or more of
3288 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3289 be copied to the output files. Only the part of the
3290 field name after the hyphen will be used in the output
3291 file. Where the letter <tt>B</tt> is used the field
3292 will appear in binary package control files, where the
3293 letter <tt>S</tt> is used in source package control
3294 files and where <tt>C</tt> is used in upload control
3295 (<tt>.changes</tt>) files.
3299 For example, if the main source information control file
3302 XBS-Comment: I stand between the candle and the star.
3304 then the binary and source package control files will contain the
3307 Comment: I stand between the candle and the star.
3316 <chapt id="maintainerscripts">
3317 <heading>Package maintainer scripts and installation procedure</heading>
3320 <heading>Introduction to package maintainer scripts</heading>
3323 It is possible to supply scripts as part of a package which
3324 the package management system will run for you when your
3325 package is installed, upgraded or removed.
3329 These scripts are the files <prgn>preinst</prgn>,
3330 <prgn>postinst</prgn>, <prgn>prerm</prgn> and
3331 <prgn>postrm</prgn> in the control area of the package.
3332 They must be proper executable files; if they are scripts
3333 (which is recommended), they must start with the usual
3334 <tt>#!</tt> convention. They should be readable and
3335 executable by anyone, and must not be world-writable.
3339 The package management system looks at the exit status from
3340 these scripts. It is important that they exit with a
3341 non-zero status if there is an error, so that the package
3342 management system can stop its processing. For shell
3343 scripts this means that you <em>almost always</em> need to
3344 use <tt>set -e</tt> (this is usually true when writing shell
3345 scripts, in fact). It is also important, of course, that
3346 they don't exit with a non-zero status if everything went
3351 Additionally, packages interacting with users using
3352 <tt>debconf</tt> in the <prgn>postinst</prgn> script should
3353 install a <prgn>config</prgn> script in the control area,
3354 see <ref id="maintscriptprompt"> for details.
3358 When a package is upgraded a combination of the scripts from
3359 the old and new packages is called during the upgrade
3360 procedure. If your scripts are going to be at all
3361 complicated you need to be aware of this, and may need to
3362 check the arguments to your scripts.
3366 Broadly speaking the <prgn>preinst</prgn> is called before
3367 (a particular version of) a package is installed, and the
3368 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3369 before (a version of) a package is removed and the
3370 <prgn>postrm</prgn> afterwards.
3374 Programs called from maintainer scripts should not normally
3375 have a path prepended to them. Before installation is
3376 started, the package management system checks to see if the
3377 programs <prgn>ldconfig</prgn>,
3378 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3379 and <prgn>update-rc.d</prgn> can be found via the
3380 <tt>PATH</tt> environment variable. Those programs, and any
3381 other program that one would expect to be in the
3382 <tt>PATH</tt>, should thus be invoked without an absolute
3383 pathname. Maintainer scripts should also not reset the
3384 <tt>PATH</tt>, though they might choose to modify it by
3385 prepending or appending package-specific directories. These
3386 considerations really apply to all shell scripts.</p>
3389 <sect id="idempotency">
3390 <heading>Maintainer scripts idempotency</heading>
3393 It is necessary for the error recovery procedures that the
3394 scripts be idempotent. This means that if it is run
3395 successfully, and then it is called again, it doesn't bomb
3396 out or cause any harm, but just ensures that everything is
3397 the way it ought to be. If the first call failed, or
3398 aborted half way through for some reason, the second call
3399 should merely do the things that were left undone the first
3400 time, if any, and exit with a success status if everything
3402 This is so that if an error occurs, the user interrupts
3403 <prgn>dpkg</prgn> or some other unforeseen circumstance
3404 happens you don't leave the user with a badly-broken
3405 package when <prgn>dpkg</prgn> attempts to repeat the
3411 <sect id="controllingterminal">
3412 <heading>Controlling terminal for maintainer scripts</heading>
3415 The maintainer scripts are guaranteed to run with a
3416 controlling terminal and can interact with the user.
3417 Because these scripts may be executed with standard output
3418 redirected into a pipe for logging purposes, Perl scripts
3419 should set unbuffered output by setting <tt>$|=1</tt> so
3420 that the output is printed immediately rather than being
3424 <sect id="exitstatus">
3425 <heading>Exit status</heading>
3428 Each script must return a zero exit status for
3429 success, or a nonzero one for failure, since the package
3430 management system looks for the exit status of these scripts
3431 and determines what action to take next based on that datum.
3435 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3440 <list compact="compact">
3442 <var>new-preinst</var> <tt>install</tt>
3445 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3448 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3451 <var>old-preinst</var> <tt>abort-upgrade</tt>
3452 <var>new-version</var>
3457 <list compact="compact">
3459 <var>postinst</var> <tt>configure</tt>
3460 <var>most-recently-configured-version</var>
3463 <var>old-postinst</var> <tt>abort-upgrade</tt>
3464 <var>new-version</var>
3467 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3468 <tt>in-favour</tt> <var>package</var>
3469 <var>new-version</var>
3472 <var>postinst</var> <tt>abort-remove</tt>
3475 <var>deconfigured's-postinst</var>
3476 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3477 <var>failed-install-package</var> <var>version</var>
3478 [<tt>removing</tt> <var>conflicting-package</var>
3484 <list compact="compact">
3486 <var>prerm</var> <tt>remove</tt>
3489 <var>old-prerm</var> <tt>upgrade</tt>
3490 <var>new-version</var>
3493 <var>new-prerm</var> <tt>failed-upgrade</tt>
3494 <var>old-version</var>
3497 <var>conflictor's-prerm</var> <tt>remove</tt>
3498 <tt>in-favour</tt> <var>package</var>
3499 <var>new-version</var>
3502 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3503 <tt>in-favour</tt> <var>package-being-installed</var>
3504 <var>version</var> [<tt>removing</tt>
3505 <var>conflicting-package</var>
3511 <list compact="compact">
3513 <var>postrm</var> <tt>remove</tt>
3516 <var>postrm</var> <tt>purge</tt>
3519 <var>old-postrm</var> <tt>upgrade</tt>
3520 <var>new-version</var>
3523 <var>new-postrm</var> <tt>failed-upgrade</tt>
3524 <var>old-version</var>
3527 <var>new-postrm</var> <tt>abort-install</tt>
3530 <var>new-postrm</var> <tt>abort-install</tt>
3531 <var>old-version</var>
3534 <var>new-postrm</var> <tt>abort-upgrade</tt>
3535 <var>old-version</var>
3538 <var>disappearer's-postrm</var> <tt>disappear</tt>
3539 <var>overwriter</var>
3540 <var>overwriter-version</var>
3546 <sect id="unpackphase">
3547 <heading>Details of unpack phase of installation or upgrade</heading>
3550 The procedure on installation/upgrade/overwrite/disappear
3551 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3552 stage of <tt>dpkg --install</tt>) is as follows. In each
3553 case, if a major error occurs (unless listed below) the
3554 actions are, in general, run backwards - this means that the
3555 maintainer scripts are run with different arguments in
3556 reverse order. These are the "error unwind" calls listed
3563 If a version of the package is already installed, call
3564 <example compact="compact">
3565 <var>old-prerm</var> upgrade <var>new-version</var>
3569 If the script runs but exits with a non-zero
3570 exit status, <prgn>dpkg</prgn> will attempt:
3571 <example compact="compact">
3572 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3574 If this works, the upgrade continues. If this
3575 does not work, the error unwind:
3576 <example compact="compact">
3577 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3579 If this works, then the old-version is
3580 "Installed", if not, the old version is in a
3581 "Failed-Config" state.
3587 If a "conflicting" package is being removed at the same time,
3588 or if any package will be broken (due to <tt>Breaks</tt>):
3591 If <tt>--auto-deconfigure</tt> is
3592 specified, call, for each package to be deconfigured
3593 due to <tt>Breaks</tt>:
3594 <example compact="compact">
3595 <var>deconfigured's-prerm</var> deconfigure \
3596 in-favour <var>package-being-installed</var> <var>version</var>
3599 <example compact="compact">
3600 <var>deconfigured's-postinst</var> abort-deconfigure \
3601 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3603 The deconfigured packages are marked as
3604 requiring configuration, so that if
3605 <tt>--install</tt> is used they will be
3606 configured again if possible.
3609 If any packages depended on a conflicting
3610 package being removed and <tt>--auto-deconfigure</tt> is
3611 specified, call, for each such package:
3612 <example compact="compact">
3613 <var>deconfigured's-prerm</var> deconfigure \
3614 in-favour <var>package-being-installed</var> <var>version</var> \
3615 removing <var>conflicting-package</var> <var>version</var>
3618 <example compact="compact">
3619 <var>deconfigured's-postinst</var> abort-deconfigure \
3620 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3621 removing <var>conflicting-package</var> <var>version</var>
3623 The deconfigured packages are marked as
3624 requiring configuration, so that if
3625 <tt>--install</tt> is used they will be
3626 configured again if possible.
3629 To prepare for removal of each conflicting package, call:
3630 <example compact="compact">
3631 <var>conflictor's-prerm</var> remove \
3632 in-favour <var>package</var> <var>new-version</var>
3635 <example compact="compact">
3636 <var>conflictor's-postinst</var> abort-remove \
3637 in-favour <var>package</var> <var>new-version</var>
3646 If the package is being upgraded, call:
3647 <example compact="compact">
3648 <var>new-preinst</var> upgrade <var>old-version</var>
3650 If this fails, we call:
3652 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3659 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3661 is called. If this works, then the old version
3662 is in an "Installed" state, or else it is left
3663 in an "Unpacked" state.
3668 If it fails, then the old version is left
3669 in an "Half-Installed" state.
3676 Otherwise, if the package had some configuration
3677 files from a previous version installed (i.e., it
3678 is in the "configuration files only" state):
3679 <example compact="compact">
3680 <var>new-preinst</var> install <var>old-version</var>
3684 <var>new-postrm</var> abort-install <var>old-version</var>
3686 If this fails, the package is left in a
3687 "Half-Installed" state, which requires a
3688 reinstall. If it works, the packages is left in
3689 a "Config Files" state.
3692 Otherwise (i.e., the package was completely purged):
3693 <example compact="compact">
3694 <var>new-preinst</var> install
3697 <example compact="compact">
3698 <var>new-postrm</var> abort-install
3700 If the error-unwind fails, the package is in a
3701 "Half Installed" phase, and requires a
3702 reinstall. If the error unwind works, the
3703 package is in a not installed state.
3710 The new package's files are unpacked, overwriting any
3711 that may be on the system already, for example any
3712 from the old version of the same package or from
3713 another package. Backups of the old files are kept
3714 temporarily, and if anything goes wrong the package
3715 management system will attempt to put them back as
3716 part of the error unwind.
3720 It is an error for a package to contain files which
3721 are on the system in another package, unless
3722 <tt>Replaces</tt> is used (see <ref id="replaces">).
3724 The following paragraph is not currently the case:
3725 Currently the <tt>- - force-overwrite</tt> flag is
3726 enabled, downgrading it to a warning, but this may not
3732 It is a more serious error for a package to contain a
3733 plain file or other kind of non-directory where another
3734 package has a directory (again, unless
3735 <tt>Replaces</tt> is used). This error can be
3736 overridden if desired using
3737 <tt>--force-overwrite-dir</tt>, but this is not
3742 Packages which overwrite each other's files produce
3743 behavior which, though deterministic, is hard for the
3744 system administrator to understand. It can easily
3745 lead to "missing" programs if, for example, a package
3746 is installed which overwrites a file from another
3747 package, and is then removed again.<footnote>
3748 Part of the problem is due to what is arguably a
3749 bug in <prgn>dpkg</prgn>.
3754 A directory will never be replaced by a symbolic link
3755 to a directory or vice versa; instead, the existing
3756 state (symlink or not) will be left alone and
3757 <prgn>dpkg</prgn> will follow the symlink if there is
3766 If the package is being upgraded, call
3767 <example compact="compact">
3768 <var>old-postrm</var> upgrade <var>new-version</var>
3772 If this fails, <prgn>dpkg</prgn> will attempt:
3773 <example compact="compact">
3774 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3776 If this works, installation continues. If not,
3778 <example compact="compact">
3779 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3781 If this fails, the old version is left in an
3782 "Half Installed" state. If it works, dpkg now
3784 <example compact="compact">
3785 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3787 If this fails, the old version is left in an
3788 "Half Installed" state. If it works, dpkg now
3790 <example compact="compact">
3791 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3793 If this fails, the old version is in an
3800 This is the point of no return - if
3801 <prgn>dpkg</prgn> gets this far, it won't back off
3802 past this point if an error occurs. This will
3803 leave the package in a fairly bad state, which
3804 will require a successful re-installation to clear
3805 up, but it's when <prgn>dpkg</prgn> starts doing
3806 things that are irreversible.
3811 Any files which were in the old version of the package
3812 but not in the new are removed.
3816 The new file list replaces the old.
3820 The new maintainer scripts replace the old.
3824 Any packages all of whose files have been overwritten
3825 during the installation, and which aren't required for
3826 dependencies, are considered to have been removed.
3827 For each such package
3830 <prgn>dpkg</prgn> calls:
3831 <example compact="compact">
3832 <var>disappearer's-postrm</var> disappear \
3833 <var>overwriter</var> <var>overwriter-version</var>
3837 The package's maintainer scripts are removed.
3840 It is noted in the status database as being in a
3841 sane state, namely not installed (any conffiles
3842 it may have are ignored, rather than being
3843 removed by <prgn>dpkg</prgn>). Note that
3844 disappearing packages do not have their prerm
3845 called, because <prgn>dpkg</prgn> doesn't know
3846 in advance that the package is going to
3853 Any files in the package we're unpacking that are also
3854 listed in the file lists of other packages are removed
3855 from those lists. (This will lobotomize the file list
3856 of the "conflicting" package if there is one.)
3860 The backup files made during installation, above, are
3866 The new package's status is now sane, and recorded as
3871 Here is another point of no return - if the
3872 conflicting package's removal fails we do not unwind
3873 the rest of the installation; the conflicting package
3874 is left in a half-removed limbo.
3879 If there was a conflicting package we go and do the
3880 removal actions (described below), starting with the
3881 removal of the conflicting package's files (any that
3882 are also in the package being installed have already
3883 been removed from the conflicting package's file list,
3884 and so do not get removed now).
3890 <sect id="configdetails"><heading>Details of configuration</heading>
3893 When we configure a package (this happens with <tt>dpkg
3894 --install</tt> and <tt>dpkg --configure</tt>), we first
3895 update any <tt>conffile</tt>s and then call:
3896 <example compact="compact">
3897 <var>postinst</var> configure <var>most-recently-configured-version</var>
3902 No attempt is made to unwind after errors during
3903 configuration. If the configuration fails, the package is in
3904 a "Failed Config" state, and an error message is generated.
3908 If there is no most recently configured version
3909 <prgn>dpkg</prgn> will pass a null argument.
3912 Historical note: Truly ancient (pre-1997) versions of
3913 <prgn>dpkg</prgn> passed <tt><unknown></tt>
3914 (including the angle brackets) in this case. Even older
3915 ones did not pass a second argument at all, under any
3916 circumstance. Note that upgrades using such an old dpkg
3917 version are unlikely to work for other reasons, even if
3918 this old argument behavior is handled by your postinst script.
3924 <sect id="removedetails"><heading>Details of removal and/or
3925 configuration purging</heading>
3931 <example compact="compact">
3932 <var>prerm</var> remove
3936 If prerm fails during replacement due to conflict
3938 <var>conflictor's-postinst</var> abort-remove \
3939 in-favour <var>package</var> <var>new-version</var>
3943 <var>postinst</var> abort-remove
3947 If this fails, the package is in a "Failed-Config"
3948 state, or else it remains "Installed".
3952 The package's files are removed (except <tt>conffile</tt>s).
3955 <example compact="compact">
3956 <var>postrm</var> remove
3960 If it fails, there's no error unwind, and the package is in
3961 an "Half-Installed" state.
3966 All the maintainer scripts except the <prgn>postrm</prgn>
3971 If we aren't purging the package we stop here. Note
3972 that packages which have no <prgn>postrm</prgn> and no
3973 <tt>conffile</tt>s are automatically purged when
3974 removed, as there is no difference except for the
3975 <prgn>dpkg</prgn> status.
3979 The <tt>conffile</tt>s and any backup files
3980 (<tt>~</tt>-files, <tt>#*#</tt> files,
3981 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
3986 <example compact="compact">
3987 <var>postrm</var> purge
3991 If this fails, the package remains in a "Config-Files"
3996 The package's file list is removed.
4005 <chapt id="relationships">
4006 <heading>Declaring relationships between packages</heading>
4008 <sect id="depsyntax">
4009 <heading>Syntax of relationship fields</heading>
4012 These fields all have a uniform syntax. They are a list of
4013 package names separated by commas.
4017 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4018 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4019 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4020 control file fields of the package, which declare
4021 dependencies on other packages, the package names listed may
4022 also include lists of alternative package names, separated
4023 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4024 if any one of the alternative packages is installed, that
4025 part of the dependency is considered to be satisfied.
4029 All of the fields except for <tt>Provides</tt> may restrict
4030 their applicability to particular versions of each named
4031 package. This is done in parentheses after each individual
4032 package name; the parentheses should contain a relation from
4033 the list below followed by a version number, in the format
4034 described in <ref id="f-Version">.
4038 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4039 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4040 strictly earlier, earlier or equal, exactly equal, later or
4041 equal and strictly later, respectively. The deprecated
4042 forms <tt><</tt> and <tt>></tt> were used to mean
4043 earlier/later or equal, rather than strictly earlier/later,
4044 so they should not appear in new packages (though
4045 <prgn>dpkg</prgn> still supports them).
4049 Whitespace may appear at any point in the version
4050 specification subject to the rules in <ref
4051 id="controlsyntax">, and must appear where it's necessary to
4052 disambiguate; it is not otherwise significant. All of the
4053 relationship fields may span multiple lines. For
4054 consistency and in case of future changes to
4055 <prgn>dpkg</prgn> it is recommended that a single space be
4056 used after a version relationship and before a version
4057 number; it is also conventional to put a single space after
4058 each comma, on either side of each vertical bar, and before
4059 each open parenthesis. When wrapping a relationship field, it
4060 is conventional to do so after a comma and before the space
4061 following that comma.
4065 For example, a list of dependencies might appear as:
4066 <example compact="compact">
4069 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4074 All fields that specify build-time relationships
4075 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4076 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
4077 may be restricted to a certain set of architectures. This
4078 is indicated in brackets after each individual package name and
4079 the optional version specification. The brackets enclose a
4080 list of Debian architecture names separated by whitespace.
4081 Exclamation marks may be prepended to each of the names.
4082 (It is not permitted for some names to be prepended with
4083 exclamation marks while others aren't.) If the current Debian
4084 host architecture is not in this list and there are no
4085 exclamation marks in the list, or it is in the list with a
4086 prepended exclamation mark, the package name and the
4087 associated version specification are ignored completely for
4088 the purposes of defining the relationships.
4093 <example compact="compact">
4095 Build-Depends-Indep: texinfo
4096 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4097 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4102 Note that the binary package relationship fields such as
4103 <tt>Depends</tt> appear in one of the binary package
4104 sections of the control file, whereas the build-time
4105 relationships such as <tt>Build-Depends</tt> appear in the
4106 source package section of the control file (which is the
4111 <sect id="binarydeps">
4112 <heading>Binary Dependencies - <tt>Depends</tt>,
4113 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4114 <tt>Pre-Depends</tt>
4118 Packages can declare in their control file that they have
4119 certain relationships to other packages - for example, that
4120 they may not be installed at the same time as certain other
4121 packages, and/or that they depend on the presence of others.
4125 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4126 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4127 <tt>Breaks</tt> and <tt>Conflicts</tt> control file fields.
4131 These seven fields are used to declare a dependency
4132 relationship by one package on another. Except for
4133 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4134 depending (binary) package's control file.
4135 (<tt>Enhances</tt> appears in the recommending package's
4136 control file, and <tt>Breaks</tt> appears in the version of
4137 depended-on package which causes the named package to
4142 A <tt>Depends</tt> field takes effect <em>only</em> when a
4143 package is to be configured. It does not prevent a package
4144 being on the system in an unconfigured state while its
4145 dependencies are unsatisfied, and it is possible to replace
4146 a package whose dependencies are satisfied and which is
4147 properly installed with a different version whose
4148 dependencies are not and cannot be satisfied; when this is
4149 done the depending package will be left unconfigured (since
4150 attempts to configure it will give errors) and will not
4151 function properly. If it is necessary, a
4152 <tt>Pre-Depends</tt> field can be used, which has a partial
4153 effect even when a package is being unpacked, as explained
4154 in detail below. (The other three dependency fields,
4155 <tt>Recommends</tt>, <tt>Suggests</tt> and
4156 <tt>Enhances</tt>, are only used by the various front-ends
4157 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4158 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4162 For this reason packages in an installation run are usually
4163 all unpacked first and all configured later; this gives
4164 later versions of packages with dependencies on later
4165 versions of other packages the opportunity to have their
4166 dependencies satisfied.
4170 In case of circular dependencies, since installation or
4171 removal order honoring the dependency order can't be
4172 established, dependency loops are broken at some point
4173 (based on rules below), and some packages may not be able to
4174 rely on their dependencies being present when being
4175 installed or removed, depending on which side of the break
4176 of the circular dependency loop they happen to be on. If one
4177 of the packages in the loop has no postinst script, then the
4178 cycle will be broken at that package, so as to ensure that
4179 all postinst scripts run with the dependencies properly
4180 configured if this is possible. Otherwise the breaking point
4185 The <tt>Depends</tt> field thus allows package maintainers
4186 to impose an order in which packages should be configured.
4190 The meaning of the five dependency fields is as follows:
4192 <tag><tt>Depends</tt></tag>
4195 This declares an absolute dependency. A package will
4196 not be configured unless all of the packages listed in
4197 its <tt>Depends</tt> field have been correctly
4202 The <tt>Depends</tt> field should be used if the
4203 depended-on package is required for the depending
4204 package to provide a significant amount of
4209 The <tt>Depends</tt> field should also be used if the
4210 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4211 <prgn>postrm</prgn> scripts require the package to be
4212 present in order to run. Note, however, that the
4213 <prgn>postrm</prgn> cannot rely on any non-essential
4214 packages to be present during the <tt>purge</tt>
4218 <tag><tt>Recommends</tt></tag>
4221 This declares a strong, but not absolute, dependency.
4225 The <tt>Recommends</tt> field should list packages
4226 that would be found together with this one in all but
4227 unusual installations.
4231 <tag><tt>Suggests</tt></tag>
4233 This is used to declare that one package may be more
4234 useful with one or more others. Using this field
4235 tells the packaging system and the user that the
4236 listed packages are related to this one and can
4237 perhaps enhance its usefulness, but that installing
4238 this one without them is perfectly reasonable.
4241 <tag><tt>Enhances</tt></tag>
4243 This field is similar to Suggests but works in the
4244 opposite direction. It is used to declare that a
4245 package can enhance the functionality of another
4249 <tag><tt>Pre-Depends</tt></tag>
4252 This field is like <tt>Depends</tt>, except that it
4253 also forces <prgn>dpkg</prgn> to complete installation
4254 of the packages named before even starting the
4255 installation of the package which declares the
4256 pre-dependency, as follows:
4260 When a package declaring a pre-dependency is about to
4261 be <em>unpacked</em> the pre-dependency can be
4262 satisfied if the depended-on package is either fully
4263 configured, <em>or even if</em> the depended-on
4264 package(s) are only unpacked or half-configured,
4265 provided that they have been configured correctly at
4266 some point in the past (and not removed or partially
4267 removed since). In this case, both the
4268 previously-configured and currently unpacked or
4269 half-configured versions must satisfy any version
4270 clause in the <tt>Pre-Depends</tt> field.
4274 When the package declaring a pre-dependency is about
4275 to be <em>configured</em>, the pre-dependency will be
4276 treated as a normal <tt>Depends</tt>, that is, it will
4277 be considered satisfied only if the depended-on
4278 package has been correctly configured.
4282 <tt>Pre-Depends</tt> should be used sparingly,
4283 preferably only by packages whose premature upgrade or
4284 installation would hamper the ability of the system to
4285 continue with any upgrade that might be in progress.
4289 <tt>Pre-Depends</tt> are also required if the
4290 <prgn>preinst</prgn> script depends on the named
4291 package. It is best to avoid this situation if
4299 When selecting which level of dependency to use you should
4300 consider how important the depended-on package is to the
4301 functionality of the one declaring the dependency. Some
4302 packages are composed of components of varying degrees of
4303 importance. Such a package should list using
4304 <tt>Depends</tt> the package(s) which are required by the
4305 more important components. The other components'
4306 requirements may be mentioned as Suggestions or
4307 Recommendations, as appropriate to the components' relative
4313 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4316 Using <tt>Breaks</tt> may cause problems for upgrades from older
4317 versions of Debian and should not be used until the stable
4318 release of Debian supports <tt>Breaks</tt>.
4322 When one binary package declares that it breaks another,
4323 <prgn>dpkg</prgn> will refuse to allow the package which
4324 declares <tt>Breaks</tt> be installed unless the broken
4325 package is deconfigured first, and it will refuse to
4326 allow the broken package to be reconfigured.
4330 A package will not be regarded as causing breakage merely
4331 because its configuration files are still installed; it must
4332 be at least half-installed.
4336 A special exception is made for packages which declare that
4337 they break their own package name or a virtual package which
4338 they provide (see below): this does not count as a real
4343 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4344 version clause; such a <tt>Breaks</tt> is introduced in the
4345 version of an (implicit or explicit) dependency which
4346 violates an assumption or reveals a bug in earlier versions
4347 of the broken package. This use of <tt>Breaks</tt> will
4348 inform higher-level package management tools that broken
4349 package must be upgraded before the new one.
4353 If the breaking package also overwrites some files from the
4354 older package, it should use <tt>Replaces</tt> (not
4355 <tt>Conflicts</tt>) to ensure this goes smoothly.
4359 <sect id="conflicts">
4360 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4363 When one binary package declares a conflict with another
4364 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4365 refuse to allow them to be installed on the system at the
4370 If one package is to be installed, the other must be removed
4371 first - if the package being installed is marked as
4372 replacing (see <ref id="replaces">) the one on the system,
4373 or the one on the system is marked as deselected, or both
4374 packages are marked <tt>Essential</tt>, then
4375 <prgn>dpkg</prgn> will automatically remove the package
4376 which is causing the conflict, otherwise it will halt the
4377 installation of the new package with an error. This
4378 mechanism is specifically designed to produce an error when
4379 the installed package is <tt>Essential</tt>, but the new
4384 A package will not cause a conflict merely because its
4385 configuration files are still installed; it must be at least
4390 A special exception is made for packages which declare a
4391 conflict with their own package name, or with a virtual
4392 package which they provide (see below): this does not
4393 prevent their installation, and allows a package to conflict
4394 with others providing a replacement for it. You use this
4395 feature when you want the package in question to be the only
4396 package providing some feature.
4400 A <tt>Conflicts</tt> entry should almost never have an
4401 "earlier than" version clause. This would prevent
4402 <prgn>dpkg</prgn> from upgrading or installing the package
4403 which declared such a conflict until the upgrade or removal
4404 of the conflicted-with package had been completed. Instead,
4405 <tt>Breaks</tt> may be used (once <tt>Breaks</tt> is supported
4406 by the stable release of Debian).
4410 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4414 As well as the names of actual ("concrete") packages, the
4415 package relationship fields <tt>Depends</tt>,
4416 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4417 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4418 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4419 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4420 may mention "virtual packages".
4424 A <em>virtual package</em> is one which appears in the
4425 <tt>Provides</tt> control file field of another package.
4426 The effect is as if the package(s) which provide a
4427 particular virtual package name had been listed by name
4428 everywhere the virtual package name appears. (See also <ref
4433 If there are both concrete and virtual packages of the same
4434 name, then the dependency may be satisfied (or the conflict
4435 caused) by either the concrete package with the name in
4436 question or any other concrete package which provides the
4437 virtual package with the name in question. This is so that,
4438 for example, supposing we have
4439 <example compact="compact">
4442 </example> and someone else releases an enhanced version of
4443 the <tt>bar</tt> package they can say:
4444 <example compact="compact">
4448 and the <tt>bar-plus</tt> package will now also satisfy the
4449 dependency for the <tt>foo</tt> package.
4453 If a relationship field has a version number attached
4454 then only real packages will be considered to see whether
4455 the relationship is satisfied (or the prohibition violated,
4456 for a conflict or breakage) - it is assumed that a real
4457 package which provides the virtual package is not of the
4458 "right" version. So, a <tt>Provides</tt> field may not
4459 contain version numbers, and the version number of the
4460 concrete package which provides a particular virtual package
4461 will not be looked at when considering a dependency on or
4462 conflict with the virtual package name.
4466 It is likely that the ability will be added in a future
4467 release of <prgn>dpkg</prgn> to specify a version number for
4468 each virtual package it provides. This feature is not yet
4469 present, however, and is expected to be used only
4474 If you want to specify which of a set of real packages
4475 should be the default to satisfy a particular dependency on
4476 a virtual package, you should list the real package as an
4477 alternative before the virtual one.
4482 <sect id="replaces"><heading>Overwriting files and replacing
4483 packages - <tt>Replaces</tt></heading>
4486 Packages can declare in their control file that they should
4487 overwrite files in certain other packages, or completely
4488 replace other packages. The <tt>Replaces</tt> control file
4489 field has these two distinct purposes.
4492 <sect1><heading>Overwriting files in other packages</heading>
4495 Firstly, as mentioned before, it is usually an error for a
4496 package to contain files which are on the system in
4501 However, if the overwriting package declares that it
4502 <tt>Replaces</tt> the one containing the file being
4503 overwritten, then <prgn>dpkg</prgn> will replace the file
4504 from the old package with that from the new. The file
4505 will no longer be listed as "owned" by the old package.
4509 If a package is completely replaced in this way, so that
4510 <prgn>dpkg</prgn> does not know of any files it still
4511 contains, it is considered to have "disappeared". It will
4512 be marked as not wanted on the system (selected for
4513 removal) and not installed. Any <tt>conffile</tt>s
4514 details noted for the package will be ignored, as they
4515 will have been taken over by the overwriting package. The
4516 package's <prgn>postrm</prgn> script will be run with a
4517 special argument to allow the package to do any final
4518 cleanup required. See <ref id="mscriptsinstact">.
4521 Replaces is a one way relationship -- you have to
4522 install the replacing package after the replaced
4529 For this usage of <tt>Replaces</tt>, virtual packages (see
4530 <ref id="virtual">) are not considered when looking at a
4531 <tt>Replaces</tt> field - the packages declared as being
4532 replaced must be mentioned by their real names.
4536 Furthermore, this usage of <tt>Replaces</tt> only takes
4537 effect when both packages are at least partially on the
4538 system at once, so that it can only happen if they do not
4539 conflict or if the conflict has been overridden.
4544 <sect1><heading>Replacing whole packages, forcing their
4548 Secondly, <tt>Replaces</tt> allows the packaging system to
4549 resolve which package should be removed when there is a
4550 conflict - see <ref id="conflicts">. This usage only
4551 takes effect when the two packages <em>do</em> conflict,
4552 so that the two usages of this field do not interfere with
4557 In this situation, the package declared as being replaced
4558 can be a virtual package, so for example, all mail
4559 transport agents (MTAs) would have the following fields in
4560 their control files:
4561 <example compact="compact">
4562 Provides: mail-transport-agent
4563 Conflicts: mail-transport-agent
4564 Replaces: mail-transport-agent
4566 ensuring that only one MTA can be installed at any one
4571 <sect id="sourcebinarydeps">
4572 <heading>Relationships between source and binary packages -
4573 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4574 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4578 Source packages that require certain binary packages to be
4579 installed or absent at the time of building the package
4580 can declare relationships to those binary packages.
4584 This is done using the <tt>Build-Depends</tt>,
4585 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4586 <tt>Build-Conflicts-Indep</tt> control file fields.
4590 Build-dependencies on "build-essential" binary packages can be
4591 omitted. Please see <ref id="pkg-relations"> for more information.
4595 The dependencies and conflicts they define must be satisfied
4596 (as defined earlier for binary packages) in order to invoke
4597 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4599 If you make "build-arch" or "binary-arch", you need
4600 Build-Depends. If you make "build-indep" or
4601 "binary-indep", you need Build-Depends and
4602 Build-Depends-Indep. If you make "build" or "binary",
4606 There is no Build-Depends-Arch; this role is essentially
4607 met with Build-Depends. Anyone building the
4608 <tt>build-indep</tt> and binary-indep<tt></tt> targets
4609 is basically assumed to be building the whole package
4610 anyway and so installs all build dependencies. The
4611 autobuilders use <tt>dpkg-buildpackage -B</tt>, which
4612 calls <tt>build</tt> (not <tt>build-arch</tt>, since it
4613 does not yet know how to check for its existence) and
4614 <tt>binary-arch</tt>.
4617 The purpose of the original split, I recall, was so that
4618 the autobuilders wouldn't need to install extra packages
4619 needed only for the binary-indep targets. But without a
4620 build-arch/build-indep split, this didn't work, since
4621 most of the work is done in the build target, not in the
4627 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4629 The <tt>Build-Depends</tt> and
4630 <tt>Build-Conflicts</tt> fields must be satisfied when
4631 any of the following targets is invoked:
4632 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4633 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4634 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4636 <tag><tt>Build-Depends-Indep</tt>,
4637 <tt>Build-Conflicts-Indep</tt></tag>
4639 The <tt>Build-Depends-Indep</tt> and
4640 <tt>Build-Conflicts-Indep</tt> fields must be
4641 satisfied when any of the following targets is
4642 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4643 <tt>binary</tt> and <tt>binary-indep</tt>.
4653 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4656 Packages containing shared libraries must be constructed with
4657 a little care to make sure that the shared library is always
4658 available. This is especially important for packages whose
4659 shared libraries are vitally important, such as the C library
4660 (currently <tt>libc6</tt>).
4664 Packages involving shared libraries should be split up into
4665 several binary packages. This section mostly deals with how
4666 this separation is to be accomplished; rules for files within
4667 the shared library packages are in <ref id="libraries"> instead.
4670 <sect id="sharedlibs-runtime">
4671 <heading>Run-time shared libraries</heading>
4674 The run-time shared library needs to be placed in a package
4675 whose name changes whenever the shared object version
4678 Since it is common place to install several versions of a
4679 package that just provides shared libraries, it is a
4680 good idea that the library package should not
4681 contain any extraneous non-versioned files, unless they
4682 happen to be in versioned directories.</p>
4684 The most common mechanism is to place it in a package
4686 <package><var>libraryname</var><var>soversion</var></package>,
4687 where <file><var>soversion</var></file> is the version number
4688 in the soname of the shared library<footnote>
4689 The soname is the shared object name: it's the thing
4690 that has to match exactly between building an executable
4691 and running it for the dynamic linker to be able run the
4692 program. For example, if the soname of the library is
4693 <file>libfoo.so.6</file>, the library package would be
4694 called <file>libfoo6</file>.
4696 Alternatively, if it would be confusing to directly append
4697 <var>soversion</var> to <var>libraryname</var> (e.g. because
4698 <var>libraryname</var> itself ends in a number), you may use
4699 <package><var>libraryname</var>-<var>soversion</var></package> and
4700 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4705 If your package includes run-time support programs that
4706 do not need to be invoked manually by users, but are
4707 nevertheless required for the package to function, then it
4708 is recommended that these programs are placed
4709 (if they are binary) in a subdirectory of
4710 <file>/usr/lib</file>, preferably under
4711 <file>/usr/lib/</file><var>package-name</var>.
4712 If the program is architecture independent, the
4713 recommendation is for it to be placed in a subdirectory of
4714 <file>/usr/share</file> instead, preferably under
4715 <file>/usr/share/</file><var>package-name</var>.
4720 If you have several shared libraries built from the same
4721 source tree you may lump them all together into a single
4722 shared library package, provided that you change all of
4723 their sonames at once (so that you don't get filename
4724 clashes if you try to install different versions of the
4725 combined shared libraries package).
4729 The package should install the shared libraries under
4730 their normal names. For example, the <package>libgdbm3</package>
4731 package should install <file>libgdbm.so.3.0.0</file> as
4732 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4733 renamed or re-linked by any <prgn>prerm</prgn> or
4734 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4735 of renaming things safely without affecting running programs,
4736 and attempts to interfere with this are likely to lead to
4741 Shared libraries should not be installed executable, since
4742 the dynamic linker does not require this and trying to
4743 execute a shared library usually results in a core dump.
4747 The run-time library package should include the symbolic link that
4748 <prgn>ldconfig</prgn> would create for the shared libraries.
4749 For example, the <package>libgdbm3</package> package should include
4750 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4751 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4752 linker (for example <prgn>ld.so</prgn> or
4753 <prgn>ld-linux.so.*</prgn>) can find the library between the
4754 time that <prgn>dpkg</prgn> installs it and the time that
4755 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4757 The package management system requires the library to be
4758 placed before the symbolic link pointing to it in the
4759 <file>.deb</file> file. This is so that when
4760 <prgn>dpkg</prgn> comes to install the symlink
4761 (overwriting the previous symlink pointing at an older
4762 version of the library), the new shared library is already
4763 in place. In the past, this was achieved by creating the
4764 library in the temporary packaging directory before
4765 creating the symlink. Unfortunately, this was not always
4766 effective, since the building of the tar file in the
4767 <file>.deb</file> depended on the behavior of the underlying
4768 file system. Some file systems (such as reiserfs) reorder
4769 the files so that the order of creation is forgotten.
4770 Since version 1.7.0, <prgn>dpkg</prgn>
4771 reorders the files itself as necessary when building a
4772 package. Thus it is no longer important to concern
4773 oneself with the order of file creation.
4777 <sect1 id="ldconfig">
4778 <heading><tt>ldconfig</tt></heading>
4781 Any package installing shared libraries in one of the default
4782 library directories of the dynamic linker (which are currently
4783 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4784 listed in <file>/etc/ld.so.conf</file><footnote>
4786 <list compact="compact">
4787 <item>/usr/local/lib</item>
4788 <item>/usr/lib/libc5-compat</item>
4789 <item>/lib/libc5-compat</item>
4792 must use <prgn>ldconfig</prgn> to update the shared library
4797 The package maintainer scripts must only call
4798 <prgn>ldconfig</prgn> under these circumstances:
4799 <list compact="compact">
4800 <item>When the <prgn>postinst</prgn> script is run with a
4801 first argument of <tt>configure</tt>, the script must call
4802 <prgn>ldconfig</prgn>, and may optionally invoke
4803 <prgn>ldconfig</prgn> at other times.
4805 <item>When the <prgn>postrm</prgn> script is run with a
4806 first argument of <tt>remove</tt>, the script should call
4807 <prgn>ldconfig</prgn>.
4812 During install or upgrade, the preinst is called before
4813 the new files are installed, so calling "ldconfig" is
4814 pointless. The preinst of an existing package can also be
4815 called if an upgrade fails. However, this happens during
4816 the critical time when a shared libs may exist on-disk
4817 under a temporary name. Thus, it is dangerous and
4818 forbidden by current policy to call "ldconfig" at this
4823 When a package is installed or upgraded, "postinst
4824 configure" runs after the new files are safely on-disk.
4825 Since it is perfectly safe to invoke ldconfig
4826 unconditionally in a postinst, it is OK for a package to
4827 simply put ldconfig in its postinst without checking the
4828 argument. The postinst can also be called to recover from
4829 a failed upgrade. This happens before any new files are
4830 unpacked, so there is no reason to call "ldconfig" at this
4835 For a package that is being removed, prerm is
4836 called with all the files intact, so calling ldconfig is
4837 useless. The other calls to "prerm" happen in the case of
4838 upgrade at a time when all the files of the old package
4839 are on-disk, so again calling "ldconfig" is pointless.
4843 postrm, on the other hand, is called with the "remove"
4844 argument just after the files are removed, so this is
4845 the proper time to call "ldconfig" to notify the system
4846 of the fact that the shared libraries from the package
4847 are removed. The postrm can be called at several other
4848 times. At the time of "postrm purge", "postrm
4849 abort-install", or "postrm abort-upgrade", calling
4850 "ldconfig" is useless because the shared lib files are
4851 not on-disk. However, when "postrm" is invoked with
4852 arguments "upgrade", "failed-upgrade", or "disappear", a
4853 shared lib may exist on-disk under a temporary filename.
4861 <sect id="sharedlibs-runtime-progs">
4862 <heading>Run-time support programs</heading>
4865 If your package has some run-time support programs which use
4866 the shared library you must not put them in the shared
4867 library package. If you do that then you won't be able to
4868 install several versions of the shared library without
4869 getting filename clashes.
4873 Instead, either create another package for the runtime binaries
4874 (this package might typically be named
4875 <package><var>libraryname</var>-runtime</package>; note the absence
4876 of the <var>soversion</var> in the package name), or if the
4877 development package is small, include them in there.
4881 <sect id="sharedlibs-static">
4882 <heading>Static libraries</heading>
4885 The static library (<file><var>libraryname.a</var></file>)
4886 is usually provided in addition to the shared version.
4887 It is placed into the development package (see below).
4891 In some cases, it is acceptable for a library to be
4892 available in static form only; these cases include:
4894 <item>libraries for languages whose shared library support
4895 is immature or unstable</item>
4896 <item>libraries whose interfaces are in flux or under
4897 development (commonly the case when the library's
4898 major version number is zero, or where the ABI breaks
4899 across patchlevels)</item>
4900 <item>libraries which are explicitly intended to be
4901 available only in static form by their upstream
4906 <sect id="sharedlibs-dev">
4907 <heading>Development files</heading>
4910 The development files associated to a shared library need to be
4911 placed in a package called
4912 <package><var>libraryname</var><var>soversion</var>-dev</package>,
4913 or if you prefer only to support one development version at a
4914 time, <package><var>libraryname</var>-dev</package>.
4918 In case several development versions of a library exist, you may
4919 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
4920 <ref id="conflicts">) to ensure that the user only installs one
4921 development version at a time (as different development versions are
4922 likely to have the same header files in them, which would cause a
4923 filename clash if both were installed).
4927 The development package should contain a symlink for the associated
4928 shared library without a version number. For example, the
4929 <package>libgdbm-dev</package> package should include a symlink
4930 from <file>/usr/lib/libgdbm.so</file> to
4931 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
4932 (<prgn>ld</prgn>) when compiling packages, as it will only look for
4933 <file>libgdbm.so</file> when compiling dynamically.
4937 <sect id="sharedlibs-intradeps">
4938 <heading>Dependencies between the packages of the same library</heading>
4941 Typically the development version should have an exact
4942 version dependency on the runtime library, to make sure that
4943 compilation and linking happens correctly. The
4944 <tt>${binary:Version}</tt> substitution variable can be
4945 useful for this purpose.
4947 Previously, <tt>${Source-Version}</tt> was used, but its name
4948 was confusing and it has been deprecated since dpkg 1.13.19.
4953 <sect id="sharedlibs-shlibdeps">
4954 <heading>Dependencies between the library and other packages -
4955 the <tt>shlibs</tt> system</heading>
4958 If a package contains a binary or library which links to a
4959 shared library, we must ensure that when the package is
4960 installed on the system, all of the libraries needed are
4961 also installed. This requirement led to the creation of the
4962 <tt>shlibs</tt> system, which is very simple in its design:
4963 any package which <em>provides</em> a shared library also
4964 provides information on the package dependencies required to
4965 ensure the presence of this library, and any package which
4966 <em>uses</em> a shared library uses this information to
4967 determine the dependencies it requires. The files which
4968 contain the mapping from shared libraries to the necessary
4969 dependency information are called <file>shlibs</file> files.
4973 Thus, when a package is built which contains any shared
4974 libraries, it must provide a <file>shlibs</file> file for other
4975 packages to use, and when a package is built which contains
4976 any shared libraries or compiled binaries, it must run
4977 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
4978 on these to determine the libraries used and hence the
4979 dependencies needed by this package.<footnote>
4981 In the past, the shared libraries linked to were
4982 determined by calling <prgn>ldd</prgn>, but now
4983 <prgn>objdump</prgn> is used to do this. The only
4984 change this makes to package building is that
4985 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
4986 libraries, whereas in the past this was unnecessary.
4987 The rest of this footnote explains the advantage that
4992 We say that a binary <tt>foo</tt> <em>directly</em> uses
4993 a library <tt>libbar</tt> if it is explicitly linked
4994 with that library (that is, it uses the flag
4995 <tt>-lbar</tt> during the linking stage). Other
4996 libraries that are needed by <tt>libbar</tt> are linked
4997 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
4998 linker will load them automatically when it loads
4999 <tt>libbar</tt>. A package should depend on
5000 the libraries it directly uses, and the dependencies for
5001 those libraries should automatically pull in the other
5006 Unfortunately, the <prgn>ldd</prgn> program shows both
5007 the directly and indirectly used libraries, meaning that
5008 the dependencies determined included both direct and
5009 indirect dependencies. The use of <prgn>objdump</prgn>
5010 avoids this problem by determining only the directly
5015 A good example of where this helps is the following. We
5016 could update <tt>libimlib</tt> with a new version that
5017 supports a new graphics format called dgf (but retaining
5018 the same major version number). If we used the old
5019 <prgn>ldd</prgn> method, every package that uses
5020 <tt>libimlib</tt> would need to be recompiled so it
5021 would also depend on <tt>libdgf</tt> or it wouldn't run
5022 due to missing symbols. However with the new system,
5023 packages using <tt>libimlib</tt> can rely on
5024 <tt>libimlib</tt> itself having the dependency on
5025 <tt>libdgf</tt> and so they would not need rebuilding.
5031 In the following sections, we will first describe where the
5032 various <tt>shlibs</tt> files are to be found, then how to
5033 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5034 file format and how to create them if your package contains a
5039 <heading>The <tt>shlibs</tt> files present on the system</heading>
5042 There are several places where <tt>shlibs</tt> files are
5043 found. The following list gives them in the order in which
5045 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5046 (The first one which gives the required information is used.)
5052 <p><file>debian/shlibs.local</file></p>
5055 This lists overrides for this package. Its use is
5056 described below (see <ref id="shlibslocal">).
5061 <p><file>/etc/dpkg/shlibs.override</file></p>
5064 This lists global overrides. This list is normally
5065 empty. It is maintained by the local system
5071 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5074 When packages are being built, any
5075 <file>debian/shlibs</file> files are copied into the
5076 control file area of the temporary build directory and
5077 given the name <file>shlibs</file>. These files give
5078 details of any shared libraries included in the
5080 An example may help here. Let us say that the
5081 source package <tt>foo</tt> generates two binary
5082 packages, <tt>libfoo2</tt> and
5083 <tt>foo-runtime</tt>. When building the binary
5084 packages, the two packages are created in the
5085 directories <file>debian/libfoo2</file> and
5086 <file>debian/foo-runtime</file> respectively.
5087 (<file>debian/tmp</file> could be used instead of one
5088 of these.) Since <tt>libfoo2</tt> provides the
5089 <tt>libfoo</tt> shared library, it will require a
5090 <tt>shlibs</tt> file, which will be installed in
5091 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
5093 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
5094 when <prgn>dpkg-shlibdeps</prgn> is run on the
5096 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
5098 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5099 determine whether <tt>foo-prog</tt>'s library
5100 dependencies are satisfied by any of the libraries
5101 provided by <tt>libfoo2</tt>. For this reason,
5102 <prgn>dpkg-shlibdeps</prgn> must only be run once
5103 all of the individual binary packages'
5104 <tt>shlibs</tt> files have been installed into the
5111 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5114 These are the <file>shlibs</file> files corresponding to
5115 all of the packages installed on the system, and are
5116 maintained by the relevant package maintainers.
5121 <p><file>/etc/dpkg/shlibs.default</file></p>
5124 This file lists any shared libraries whose packages
5125 have failed to provide correct <file>shlibs</file> files.
5126 It was used when the <file>shlibs</file> setup was first
5127 introduced, but it is now normally empty. It is
5128 maintained by the <tt>dpkg</tt> maintainer.
5136 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5137 <file>shlibs</file> files</heading>
5141 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5142 into your <file>debian/rules</file> file. If your package
5143 contains only compiled binaries and libraries (but no scripts),
5144 you can use a command such as:
5145 <example compact="compact">
5146 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5147 debian/tmp/usr/lib/*
5149 Otherwise, you will need to explicitly list the compiled
5150 binaries and libraries.<footnote>
5151 If you are using <tt>debhelper</tt>, the
5152 <prgn>dh_shlibdeps</prgn> program will do this work for
5153 you. It will also correctly handle multi-binary
5159 This command puts the dependency information into the
5160 <file>debian/substvars</file> file, which is then used by
5161 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5162 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5163 field in the control file for this to work.
5167 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
5168 done. If it does complain you might need to create your own
5169 <file>debian/shlibs.local</file> file, as explained below (see
5170 <ref id="shlibslocal">).
5174 If you have multiple binary packages, you will need to call
5175 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5176 compiled libraries or binaries. In such a case, you will
5177 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5178 utilities to specify a different <file>substvars</file> file.
5182 If you are creating a udeb for use in the Debian Installer, you
5183 will need to specify that <prgn>dpkg-shlibdeps</prgn> should use
5184 the dependency line of type <tt>udeb</tt> by adding
5185 <tt>-tudeb</tt> as option<footnote>
5186 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5187 will automatically add this option if it knows it is
5189 </footnote>. If there is no dependency line of type <tt>udeb</tt>
5190 in the <file>shlibs</file> file, <prgn>dpkg-shlibdeps</prgn> will
5191 fall back to the regular dependency line.
5195 For more details on dpkg-shlibdeps, please see
5196 <ref id="pkg-dpkg-shlibdeps"> and
5197 <manref name="dpkg-shlibdeps" section="1">.
5202 <heading>The <file>shlibs</file> File Format</heading>
5205 Each <file>shlibs</file> file has the same format. Lines
5206 beginning with <tt>#</tt> are considered to be comments and
5207 are ignored. Each line is of the form:
5208 <example compact="compact">
5209 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5214 We will explain this by reference to the example of the
5215 <tt>zlib1g</tt> package, which (at the time of writing)
5216 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5220 <var>type</var> is an optional element that indicates the type
5221 of package for which the line is valid. The only type currently
5222 in use is <tt>udeb</tt>. The colon and space after the type are
5227 <var>library-name</var> is the name of the shared library,
5228 in this case <tt>libz</tt>. (This must match the name part
5229 of the soname, see below.)
5233 <var>soname-version</var> is the version part of the soname of
5234 the library. The soname is the thing that must exactly match
5235 for the library to be recognized by the dynamic linker, and is
5237 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5238 example, <tt>libz.so.1</tt>.<footnote>
5239 This can be determined using the command
5240 <example compact="compact">
5241 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5244 The version part is the part which comes after
5245 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
5249 <var>dependencies</var> has the same syntax as a dependency
5250 field in a binary package control file. It should give
5251 details of which packages are required to satisfy a binary
5252 built against the version of the library contained in the
5253 package. See <ref id="depsyntax"> for details.
5257 In our example, if the first version of the <tt>zlib1g</tt>
5258 package which contained a minor number of at least
5259 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5260 <tt>shlibs</tt> entry for this library could say:
5261 <example compact="compact">
5262 libz 1 zlib1g (>= 1:1.1.3)
5264 The version-specific dependency is to avoid warnings from
5265 the dynamic linker about using older shared libraries with
5270 As zlib1g also provides a udeb containing the shared library,
5271 there would also be a second line:
5272 <example compact="compact">
5273 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5279 <heading>Providing a <file>shlibs</file> file</heading>
5282 If your package provides a shared library, you need to create
5283 a <file>shlibs</file> file following the format described above.
5284 It is usual to call this file <file>debian/shlibs</file> (but if
5285 you have multiple binary packages, you might want to call it
5286 <file>debian/shlibs.<var>package</var></file> instead). Then
5287 let <file>debian/rules</file> install it in the control area:
5288 <example compact="compact">
5289 install -m644 debian/shlibs debian/tmp/DEBIAN
5291 or, in the case of a multi-binary package:
5292 <example compact="compact">
5293 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5295 An alternative way of doing this is to create the
5296 <file>shlibs</file> file in the control area directly from
5297 <file>debian/rules</file> without using a <file>debian/shlibs</file>
5298 file at all,<footnote>
5299 This is what <prgn>dh_makeshlibs</prgn> in the
5300 <tt>debhelper</tt> suite does. If your package also has a udeb
5301 that provides a shared library, <prgn>dh_makeshlibs</prgn> can
5302 automatically generate the <tt>udeb:</tt> lines if you specify
5303 the name of the udeb with the <tt>--add-udeb</tt> option.
5305 since the <file>debian/shlibs</file> file itself is ignored by
5306 <prgn>dpkg-shlibdeps</prgn>.
5310 As <prgn>dpkg-shlibdeps</prgn> reads the
5311 <file>DEBIAN/shlibs</file> files in all of the binary packages
5312 being built from this source package, all of the
5313 <file>DEBIAN/shlibs</file> files should be installed before
5314 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5319 <sect1 id="shlibslocal">
5320 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
5323 This file is intended only as a <em>temporary</em> fix if
5324 your binaries or libraries depend on a library whose package
5325 does not yet provide a correct <file>shlibs</file> file.
5329 We will assume that you are trying to package a binary
5330 <tt>foo</tt>. When you try running
5331 <prgn>dpkg-shlibdeps</prgn> you get the following error
5332 message (<tt>-O</tt> displays the dependency information on
5333 <tt>stdout</tt> instead of writing it to
5334 <tt>debian/substvars</tt>, and the lines have been wrapped
5335 for ease of reading):
5336 <example compact="compact">
5337 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
5338 dpkg-shlibdeps: warning: unable to find dependency
5339 information for shared library libbar (soname 1,
5340 path /usr/lib/libbar.so.1, dependency field Depends)
5341 shlibs:Depends=libc6 (>= 2.2.2-2)
5343 You can then run <prgn>ldd</prgn> on the binary to find the
5344 full location of the library concerned:
5345 <example compact="compact">
5347 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5348 libc.so.6 => /lib/libc.so.6 (0x40032000)
5349 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5351 So the <prgn>foo</prgn> binary depends on the
5352 <prgn>libbar</prgn> shared library, but no package seems to
5353 provide a <file>*.shlibs</file> file handling
5354 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5355 determine the package responsible:
5356 <example compact="compact">
5357 $ dpkg -S /usr/lib/libbar.so.1
5358 bar1: /usr/lib/libbar.so.1
5359 $ dpkg -s bar1 | grep Version
5362 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5363 is the one we are using. Now we can file a bug against the
5364 <tt>bar1</tt> package and create our own
5365 <file>debian/shlibs.local</file> to locally fix the problem.
5366 Including the following line into your
5367 <file>debian/shlibs.local</file> file:
5368 <example compact="compact">
5369 libbar 1 bar1 (>= 1.0-1)
5371 should allow the package build to work.
5375 As soon as the maintainer of <tt>bar1</tt> provides a
5376 correct <file>shlibs</file> file, you should remove this line
5377 from your <file>debian/shlibs.local</file> file. (You should
5378 probably also then have a versioned <tt>Build-Depends</tt>
5379 on <tt>bar1</tt> to help ensure that others do not have the
5380 same problem building your package.)
5389 <chapt id="opersys"><heading>The Operating System</heading>
5392 <heading>File system hierarchy</heading>
5396 <heading>File system Structure</heading>
5399 The location of all installed files and directories must
5400 comply with the File system Hierarchy Standard (FHS),
5401 version 2.3, with the exceptions noted below, and except
5402 where doing so would violate other terms of Debian
5403 Policy. The following exceptions to the FHS apply:
5408 Legacy XFree86 servers are permitted to retain the
5409 configuration file location
5410 <file>/etc/X11/XF86Config-4</file>.
5415 The optional rules related to user specific
5416 configuration files for applications are stored in
5417 the user's home directory are relaxed. It is
5418 recommended that such files start with the
5419 '<tt>.</tt>' character (a "dot file"), and if an
5420 application needs to create more than one dot file
5421 then the preferred placement is in a subdirectory
5422 with a name starting with a '.' character, (a "dot
5423 directory"). In this case it is recommended the
5424 configuration files not start with the '.'
5430 The requirement for amd64 to use <file>/lib64</file>
5431 for 64 bit binaries is removed.
5436 The requirement that
5437 <file>/usr/local/share/man</file> be "synonymous"
5438 with <file>/usr/local/man</file> is relaxed to a
5443 The requirement that windowmanagers with a single
5444 configuration file call it <file>system.*wmrc</file>
5445 is removed, as is the restriction that the window
5446 manager subdirectory be named identically to the
5447 window manager name itself.
5452 The requirement that boot manager configuration
5453 files live in <file>/etc</file>, or at least are
5454 symlinked there, is relaxed to a recommendation.
5461 The version of this document referred here can be
5462 found in the <tt>debian-policy</tt> package or on <url
5463 id="http://www.debian.org/doc/packaging-manuals/fhs/"
5464 name="FHS (Debian copy)"> alongside this manual (or, if
5465 you have the <package>debian-policy</package> installed,
5467 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5468 (local copy)">). The
5469 latest version, which may be a more recent version, may
5471 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5472 Specific questions about following the standard may be
5473 asked on the <tt>debian-devel</tt> mailing list, or
5474 referred to the FHS mailing list (see the
5475 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5481 <heading>Site-specific programs</heading>
5484 As mandated by the FHS, packages must not place any
5485 files in <file>/usr/local</file>, either by putting them in
5486 the file system archive to be unpacked by <prgn>dpkg</prgn>
5487 or by manipulating them in their maintainer scripts.
5491 However, the package may create empty directories below
5492 <file>/usr/local</file> so that the system administrator knows
5493 where to place site-specific files. These are not
5494 directories <em>in</em> <file>/usr/local</file>, but are
5495 children of directories in <file>/usr/local</file>. These
5496 directories (<file>/usr/local/*/dir/</file>)
5497 should be removed on package removal if they are
5502 Note, that this applies only to directories <em>below</em>
5503 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
5504 Packages must not create sub-directories in the directory
5505 <file>/usr/local</file> itself, except those listed in FHS,
5506 section 4.5. However, you may create directories below
5507 them as you wish. You must not remove any of the
5508 directories listed in 4.5, even if you created them.
5512 Since <file>/usr/local</file> can be mounted read-only from a
5513 remote server, these directories must be created and
5514 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5515 maintainer scripts and not be included in the
5516 <file>.deb</file> archive. These scripts must not fail if
5517 either of these operations fail.
5521 For example, the <tt>emacsen-common</tt> package could
5522 contain something like
5523 <example compact="compact">
5524 if [ ! -e /usr/local/share/emacs ]
5526 if mkdir /usr/local/share/emacs 2>/dev/null
5528 chown root:staff /usr/local/share/emacs
5529 chmod 2775 /usr/local/share/emacs
5533 in its <prgn>postinst</prgn> script, and
5534 <example compact="compact">
5535 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5536 rmdir /usr/local/share/emacs 2>/dev/null || true
5538 in the <prgn>prerm</prgn> script. (Note that this form is
5539 used to ensure that if the script is interrupted, the
5540 directory <file>/usr/local/share/emacs</file> will still be
5545 If you do create a directory in <file>/usr/local</file> for
5546 local additions to a package, you should ensure that
5547 settings in <file>/usr/local</file> take precedence over the
5548 equivalents in <file>/usr</file>.
5552 However, because <file>/usr/local</file> and its contents are
5553 for exclusive use of the local administrator, a package
5554 must not rely on the presence or absence of files or
5555 directories in <file>/usr/local</file> for normal operation.
5559 The <file>/usr/local</file> directory itself and all the
5560 subdirectories created by the package should (by default) have
5561 permissions 2775 (group-writable and set-group-id) and be
5562 owned by <tt>root.staff</tt>.
5567 <heading>The system-wide mail directory</heading>
5569 The system-wide mail directory is <file>/var/mail</file>. This
5570 directory is part of the base system and should not owned
5571 by any particular mail agents. The use of the old
5572 location <file>/var/spool/mail</file> is deprecated, even
5573 though the spool may still be physically located there.
5574 To maintain partial upgrade compatibility for systems
5575 which have <file>/var/spool/mail</file> as their physical mail
5576 spool, packages using <file>/var/mail</file> must depend on
5577 either <package>libc6</package> (>= 2.1.3-13), or on
5578 <package>base-files</package> (>= 2.2.0), or on later
5579 versions of either one of these packages.
5585 <heading>Users and groups</heading>
5588 <heading>Introduction</heading>
5590 The Debian system can be configured to use either plain or
5595 Some user ids (UIDs) and group ids (GIDs) are reserved
5596 globally for use by certain packages. Because some
5597 packages need to include files which are owned by these
5598 users or groups, or need the ids compiled into binaries,
5599 these ids must be used on any Debian system only for the
5600 purpose for which they are allocated. This is a serious
5601 restriction, and we should avoid getting in the way of
5602 local administration policies. In particular, many sites
5603 allocate users and/or local system groups starting at 100.
5607 Apart from this we should have dynamically allocated ids,
5608 which should by default be arranged in some sensible
5609 order, but the behavior should be configurable.
5613 Packages other than <tt>base-passwd</tt> must not modify
5614 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5615 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5620 <heading>UID and GID classes</heading>
5622 The UID and GID numbers are divided into classes as
5628 Globally allocated by the Debian project, the same
5629 on every Debian system. These ids will appear in
5630 the <file>passwd</file> and <file>group</file> files of all
5631 Debian systems, new ids in this range being added
5632 automatically as the <tt>base-passwd</tt> package is
5637 Packages which need a single statically allocated
5638 uid or gid should use one of these; their
5639 maintainers should ask the <tt>base-passwd</tt>
5647 Dynamically allocated system users and groups.
5648 Packages which need a user or group, but can have
5649 this user or group allocated dynamically and
5650 differently on each system, should use <tt>adduser
5651 --system</tt> to create the group and/or user.
5652 <prgn>adduser</prgn> will check for the existence of
5653 the user or group, and if necessary choose an unused
5654 id based on the ranges specified in
5655 <file>adduser.conf</file>.
5659 <tag>1000-29999:</tag>
5662 Dynamically allocated user accounts. By default
5663 <prgn>adduser</prgn> will choose UIDs and GIDs for
5664 user accounts in this range, though
5665 <file>adduser.conf</file> may be used to modify this
5670 <tag>30000-59999:</tag>
5675 <tag>60000-64999:</tag>
5678 Globally allocated by the Debian project, but only
5679 created on demand. The ids are allocated centrally
5680 and statically, but the actual accounts are only
5681 created on users' systems on demand.
5685 These ids are for packages which are obscure or
5686 which require many statically-allocated ids. These
5687 packages should check for and create the accounts in
5688 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5689 <prgn>adduser</prgn> if it has this facility) if
5690 necessary. Packages which are likely to require
5691 further allocations should have a "hole" left after
5692 them in the allocation, to give them room to
5697 <tag>65000-65533:</tag>
5705 User <tt>nobody</tt>. The corresponding gid refers
5706 to the group <tt>nogroup</tt>.
5713 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5714 not</em> be used, because it is the error return
5723 <sect id="sysvinit">
5724 <heading>System run levels and <file>init.d</file> scripts</heading>
5726 <sect1 id="/etc/init.d">
5727 <heading>Introduction</heading>
5730 The <file>/etc/init.d</file> directory contains the scripts
5731 executed by <prgn>init</prgn> at boot time and when the
5732 init state (or "runlevel") is changed (see <manref
5733 name="init" section="8">).
5737 There are at least two different, yet functionally
5738 equivalent, ways of handling these scripts. For the sake
5739 of simplicity, this document describes only the symbolic
5740 link method. However, it must not be assumed by maintainer
5741 scripts that this method is being used, and any automated
5742 manipulation of the various runlevel behaviors by
5743 maintainer scripts must be performed using
5744 <prgn>update-rc.d</prgn> as described below and not by
5745 manually installing or removing symlinks. For information
5746 on the implementation details of the other method,
5747 implemented in the <tt>file-rc</tt> package, please refer
5748 to the documentation of that package.
5752 These scripts are referenced by symbolic links in the
5753 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5754 runlevels, <prgn>init</prgn> looks in the directory
5755 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5756 execute, where <tt><var>n</var></tt> is the runlevel that
5757 is being changed to, or <tt>S</tt> for the boot-up
5762 The names of the links all have the form
5763 <file>S<var>mm</var><var>script</var></file> or
5764 <file>K<var>mm</var><var>script</var></file> where
5765 <var>mm</var> is a two-digit number and <var>script</var>
5766 is the name of the script (this should be the same as the
5767 name of the actual script in <file>/etc/init.d</file>).
5771 When <prgn>init</prgn> changes runlevel first the targets
5772 of the links whose names start with a <tt>K</tt> are
5773 executed, each with the single argument <tt>stop</tt>,
5774 followed by the scripts prefixed with an <tt>S</tt>, each
5775 with the single argument <tt>start</tt>. (The links are
5776 those in the <file>/etc/rc<var>n</var>.d</file> directory
5777 corresponding to the new runlevel.) The <tt>K</tt> links
5778 are responsible for killing services and the <tt>S</tt>
5779 link for starting services upon entering the runlevel.
5783 For example, if we are changing from runlevel 2 to
5784 runlevel 3, init will first execute all of the <tt>K</tt>
5785 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
5786 all of the <tt>S</tt> prefixed scripts in that directory.
5787 The links starting with <tt>K</tt> will cause the
5788 referred-to file to be executed with an argument of
5789 <tt>stop</tt>, and the <tt>S</tt> links with an argument
5794 The two-digit number <var>mm</var> is used to determine
5795 the order in which to run the scripts: low-numbered links
5796 have their scripts run first. For example, the
5797 <tt>K20</tt> scripts will be executed before the
5798 <tt>K30</tt> scripts. This is used when a certain service
5799 must be started before another. For example, the name
5800 server <prgn>bind</prgn> might need to be started before
5801 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
5802 can set up its access lists. In this case, the script
5803 that starts <prgn>bind</prgn> would have a lower number
5804 than the script that starts <prgn>inn</prgn> so that it
5806 <example compact="compact">
5813 The two runlevels 0 (halt) and 6 (reboot) are slightly
5814 different. In these runlevels, the links with an
5815 <tt>S</tt> prefix are still called after those with a
5816 <tt>K</tt> prefix, but they too are called with the single
5817 argument <tt>stop</tt>.
5821 Also, if the script name ends in <tt>.sh</tt>, the script
5822 will be sourced in runlevel <tt>S</tt> rather than being
5823 run in a forked subprocess, but will be explicitly run by
5824 <prgn>sh</prgn> in all other runlevels.
5829 <heading>Writing the scripts</heading>
5832 Packages that include daemons for system services should
5833 place scripts in <file>/etc/init.d</file> to start or stop
5834 services at boot time or during a change of runlevel.
5835 These scripts should be named
5836 <file>/etc/init.d/<var>package</var></file>, and they should
5837 accept one argument, saying what to do:
5840 <tag><tt>start</tt></tag>
5841 <item>start the service,</item>
5843 <tag><tt>stop</tt></tag>
5844 <item>stop the service,</item>
5846 <tag><tt>restart</tt></tag>
5847 <item>stop and restart the service if it's already running,
5848 otherwise start the service</item>
5850 <tag><tt>reload</tt></tag>
5851 <item><p>cause the configuration of the service to be
5852 reloaded without actually stopping and restarting
5855 <tag><tt>force-reload</tt></tag>
5856 <item>cause the configuration to be reloaded if the
5857 service supports this, otherwise restart the
5861 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
5862 <tt>force-reload</tt> options should be supported by all
5863 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
5868 The <file>init.d</file> scripts must ensure that they will
5869 behave sensibly if invoked with <tt>start</tt> when the
5870 service is already running, or with <tt>stop</tt> when it
5871 isn't, and that they don't kill unfortunately-named user
5872 processes. The best way to achieve this is usually to use
5873 <prgn>start-stop-daemon</prgn>.
5877 If a service reloads its configuration automatically (as
5878 in the case of <prgn>cron</prgn>, for example), the
5879 <tt>reload</tt> option of the <file>init.d</file> script
5880 should behave as if the configuration has been reloaded
5885 The <file>/etc/init.d</file> scripts must be treated as
5886 configuration files, either (if they are present in the
5887 package, that is, in the .deb file) by marking them as
5888 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
5889 by managing them correctly in the maintainer scripts (see
5890 <ref id="config-files">). This is important since we want
5891 to give the local system administrator the chance to adapt
5892 the scripts to the local system, e.g., to disable a
5893 service without de-installing the package, or to specify
5894 some special command line options when starting a service,
5895 while making sure their changes aren't lost during the next
5900 These scripts should not fail obscurely when the
5901 configuration files remain but the package has been
5902 removed, as configuration files remain on the system after
5903 the package has been removed. Only when <prgn>dpkg</prgn>
5904 is executed with the <tt>--purge</tt> option will
5905 configuration files be removed. In particular, as the
5906 <file>/etc/init.d/<var>package</var></file> script itself is
5907 usually a <tt>conffile</tt>, it will remain on the system
5908 if the package is removed but not purged. Therefore, you
5909 should include a <tt>test</tt> statement at the top of the
5911 <example compact="compact">
5912 test -f <var>program-executed-later-in-script</var> || exit 0
5917 Often there are some variables in the <file>init.d</file>
5918 scripts whose values control the behavior of the scripts,
5919 and which a system administrator is likely to want to
5920 change. As the scripts themselves are frequently
5921 <tt>conffile</tt>s, modifying them requires that the
5922 administrator merge in their changes each time the package
5923 is upgraded and the <tt>conffile</tt> changes. To ease
5924 the burden on the system administrator, such configurable
5925 values should not be placed directly in the script.
5926 Instead, they should be placed in a file in
5927 <file>/etc/default</file>, which typically will have the same
5928 base name as the <file>init.d</file> script. This extra file
5929 should be sourced by the script when the script runs. It
5930 must contain only variable settings and comments in SUSv3
5931 <prgn>sh</prgn> format. It may either be a
5932 <tt>conffile</tt> or a configuration file maintained by
5933 the package maintainer scripts. See <ref id="config-files">
5938 To ensure that vital configurable values are always
5939 available, the <file>init.d</file> script should set default
5940 values for each of the shell variables it uses, either
5941 before sourcing the <file>/etc/default/</file> file or
5942 afterwards using something like the <tt>:
5943 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
5944 script must behave sensibly and not fail if the
5945 <file>/etc/default</file> file is deleted.
5950 <heading>Interfacing with the initscript system</heading>
5953 Maintainers should use the abstraction layer provided by
5954 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
5955 programs to deal with initscripts in their packages'
5956 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
5957 and <prgn>postrm</prgn>.
5961 Directly managing the /etc/rc?.d links and directly
5962 invoking the <file>/etc/init.d/</file> initscripts should
5963 be done only by packages providing the initscript
5964 subsystem (such as <prgn>sysv-rc</prgn> and
5965 <prgn>file-rc</prgn>).
5969 <heading>Managing the links</heading>
5972 The program <prgn>update-rc.d</prgn> is provided for
5973 package maintainers to arrange for the proper creation and
5974 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
5975 or their functional equivalent if another method is being
5976 used. This may be used by maintainers in their packages'
5977 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
5981 You must not include any <file>/etc/rc<var>n</var>.d</file>
5982 symbolic links in the actual archive or manually create or
5983 remove the symbolic links in maintainer scripts; you must
5984 use the <prgn>update-rc.d</prgn> program instead. (The
5985 former will fail if an alternative method of maintaining
5986 runlevel information is being used.) You must not include
5987 the <file>/etc/rc<var>n</var>.d</file> directories themselves
5988 in the archive either. (Only the <tt>sysvinit</tt>
5993 By default <prgn>update-rc.d</prgn> will start services in
5994 each of the multi-user state runlevels (2, 3, 4, and 5)
5995 and stop them in the halt runlevel (0), the single-user
5996 runlevel (1) and the reboot runlevel (6). The system
5997 administrator will have the opportunity to customize
5998 runlevels by simply adding, moving, or removing the
5999 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6000 symbolic links are being used, or by modifying
6001 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6006 To get the default behavior for your package, put in your
6007 <prgn>postinst</prgn> script
6008 <example compact="compact">
6009 update-rc.d <var>package</var> defaults
6011 and in your <prgn>postrm</prgn>
6012 <example compact="compact">
6013 if [ "$1" = purge ]; then
6014 update-rc.d <var>package</var> remove
6016 </example>. Note that if your package changes runlevels
6017 or priority, you may have to remove and recreate the links,
6018 since otherwise the old links may persist. Refer to the
6019 documentation of <prgn>update-rc.d</prgn>.
6023 This will use a default sequence number of 20. If it does
6024 not matter when or in which order the <file>init.d</file>
6025 script is run, use this default. If it does, then you
6026 should talk to the maintainer of the <prgn>sysvinit</prgn>
6027 package or post to <tt>debian-devel</tt>, and they will
6028 help you choose a number.
6032 For more information about using <tt>update-rc.d</tt>,
6033 please consult its man page <manref name="update-rc.d"
6039 <heading>Running initscripts</heading>
6041 The program <prgn>invoke-rc.d</prgn> is provided to make
6042 it easier for package maintainers to properly invoke an
6043 initscript, obeying runlevel and other locally-defined
6044 constraints that might limit a package's right to start,
6045 stop and otherwise manage services. This program may be
6046 used by maintainers in their packages' scripts.
6050 The package maintainer scripts must use
6051 <prgn>invoke-rc.d</prgn> to invoke the
6052 <file>/etc/init.d/*</file> initscripts, instead of
6053 calling them directly.
6057 By default, <prgn>invoke-rc.d</prgn> will pass any
6058 action requests (start, stop, reload, restart...) to the
6059 <file>/etc/init.d</file> script, filtering out requests
6060 to start or restart a service out of its intended
6065 Most packages will simply need to change:
6066 <example compact="compact">/etc/init.d/<package>
6067 <action></example> in their <prgn>postinst</prgn>
6068 and <prgn>prerm</prgn> scripts to:
6069 <example compact="compact">
6070 if which invoke-rc.d >/dev/null 2>&1; then
6071 invoke-rc.d <var>package</var> <action>
6073 /etc/init.d/<var>package</var> <action>
6079 A package should register its initscript services using
6080 <prgn>update-rc.d</prgn> before it tries to invoke them
6081 using <prgn>invoke-rc.d</prgn>. Invocation of
6082 unregistered services may fail.
6086 For more information about using
6087 <prgn>invoke-rc.d</prgn>, please consult its man page
6088 <manref name="invoke-rc.d" section="8">.
6094 <heading>Boot-time initialization</heading>
6097 There used to be another directory, <file>/etc/rc.boot</file>,
6098 which contained scripts which were run once per machine
6099 boot. This has been deprecated in favour of links from
6100 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6101 described in <ref id="/etc/init.d">. Packages must not
6102 place files in <file>/etc/rc.boot</file>.
6107 <heading>Example</heading>
6110 An example on which you can base your
6111 <file>/etc/init.d</file> scripts is found in
6112 <file>/etc/init.d/skeleton</file>.
6119 <heading>Console messages from <file>init.d</file> scripts</heading>
6122 This section describes the formats to be used for messages
6123 written to standard output by the <file>/etc/init.d</file>
6124 scripts. The intent is to improve the consistency of
6125 Debian's startup and shutdown look and feel. For this
6126 reason, please look very carefully at the details. We want
6127 the messages to have the same format in terms of wording,
6128 spaces, punctuation and case of letters.
6132 Here is a list of overall rules that should be used for
6133 messages generated by <file>/etc/init.d</file> scripts.
6139 The message should fit in one line (fewer than 80
6140 characters), start with a capital letter and end with
6141 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6145 If the script is performing some time consuming task in
6146 the background (not merely starting or stopping a
6147 program, for instance), an ellipsis (three dots:
6148 <tt>...</tt>) should be output to the screen, with no
6149 leading or tailing whitespace or line feeds.
6153 The messages should appear as if the computer is telling
6154 the user what it is doing (politely :-), but should not
6155 mention "it" directly. For example, instead of:
6156 <example compact="compact">
6157 I'm starting network daemons: nfsd mountd.
6159 the message should say
6160 <example compact="compact">
6161 Starting network daemons: nfsd mountd.
6168 <tt>init.d</tt> script should use the following standard
6169 message formats for the situations enumerated below.
6175 <p>When daemons are started</p>
6178 If the script starts one or more daemons, the output
6179 should look like this (a single line, no leading
6181 <example compact="compact">
6182 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6184 The <var>description</var> should describe the
6185 subsystem the daemon or set of daemons are part of,
6186 while <var>daemon-1</var> up to <var>daemon-n</var>
6187 denote each daemon's name (typically the file name of
6192 For example, the output of <file>/etc/init.d/lpd</file>
6194 <example compact="compact">
6195 Starting printer spooler: lpd.
6200 This can be achieved by saying
6201 <example compact="compact">
6202 echo -n "Starting printer spooler: lpd"
6203 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6206 in the script. If there are more than one daemon to
6207 start, the output should look like this:
6208 <example compact="compact">
6209 echo -n "Starting remote file system services:"
6210 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6211 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6212 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6215 This makes it possible for the user to see what is
6216 happening and when the final daemon has been started.
6217 Care should be taken in the placement of white spaces:
6218 in the example above the system administrators can
6219 easily comment out a line if they don't want to start
6220 a specific daemon, while the displayed message still
6226 <p>When a system parameter is being set</p>
6229 If you have to set up different system parameters
6230 during the system boot, you should use this format:
6231 <example compact="compact">
6232 Setting <var>parameter</var> to "<var>value</var>".
6237 You can use a statement such as the following to get
6239 <example compact="compact">
6240 echo "Setting DNS domainname to \"$domainname\"."
6245 Note that the same symbol (<tt>"</tt>) is used for the left
6246 and right quotation marks. A grave accent (<tt>`</tt>) is
6247 not a quote character; neither is an apostrophe
6253 <p>When a daemon is stopped or restarted</p>
6256 When you stop or restart a daemon, you should issue a
6257 message identical to the startup message, except that
6258 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6259 or <tt>Restarting</tt> respectively.
6263 For example, stopping the printer daemon will look like
6265 <example compact="compact">
6266 Stopping printer spooler: lpd.
6272 <p>When something is executed</p>
6275 There are several examples where you have to run a
6276 program at system startup or shutdown to perform a
6277 specific task, for example, setting the system's clock
6278 using <prgn>netdate</prgn> or killing all processes
6279 when the system shuts down. Your message should look
6281 <example compact="compact">
6282 Doing something very useful...done.
6284 You should print the <tt>done.</tt> immediately after
6285 the job has been completed, so that the user is
6286 informed why they have to wait. You can get this
6288 <example compact="compact">
6289 echo -n "Doing something very useful..."
6298 <p>When the configuration is reloaded</p>
6301 When a daemon is forced to reload its configuration
6302 files you should use the following format:
6303 <example compact="compact">
6304 Reloading <var>description</var> configuration...done.
6306 where <var>description</var> is the same as in the
6307 daemon starting message.
6315 <heading>Cron jobs</heading>
6318 Packages must not modify the configuration file
6319 <file>/etc/crontab</file>, and they must not modify the files in
6320 <file>/var/spool/cron/crontabs</file>.</p>
6323 If a package wants to install a job that has to be executed
6324 via cron, it should place a file with the name of the
6325 package in one or more of the following directories:
6326 <example compact="compact">
6331 As these directory names imply, the files within them are
6332 executed on a daily, weekly, or monthly basis,
6333 respectively. The exact times are listed in
6334 <file>/etc/crontab</file>.</p>
6337 All files installed in any of these directories must be
6338 scripts (e.g., shell scripts or Perl scripts) so that they
6339 can easily be modified by the local system administrator.
6340 In addition, they should be treated as configuration
6345 If a certain job has to be executed more frequently than
6346 daily, the package should install a file
6347 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6348 same syntax as <file>/etc/crontab</file> and is processed by
6349 <prgn>cron</prgn> automatically. The file must also be
6350 treated as a configuration file. (Note that entries in the
6351 <file>/etc/cron.d</file> directory are not handled by
6352 <prgn>anacron</prgn>. Thus, you should only use this
6353 directory for jobs which may be skipped if the system is not
6357 The scripts or crontab entries in these directories should
6358 check if all necessary programs are installed before they
6359 try to execute them. Otherwise, problems will arise when a
6360 package was removed but not purged since configuration files
6361 are kept on the system in this situation.</p>
6365 <heading>Menus</heading>
6368 The Debian <tt>menu</tt> package provides a standard
6369 interface between packages providing applications and
6370 <em>menu programs</em> (either X window managers or
6371 text-based menu programs such as <prgn>pdmenu</prgn>).
6375 All packages that provide applications that need not be
6376 passed any special command line arguments for normal
6377 operation should register a menu entry for those
6378 applications, so that users of the <tt>menu</tt> package
6379 will automatically get menu entries in their window
6380 managers, as well in shells like <tt>pdmenu</tt>.
6384 Menu entries should follow the current menu policy.
6388 The menu policy can be found in the <tt>menu-policy</tt>
6389 files in the <tt>debian-policy</tt> package.
6390 It is also available from the Debian web mirrors at
6391 <tt><url name="/doc/packaging-manuals/menu-policy/"
6392 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6396 Please also refer to the <em>Debian Menu System</em>
6397 documentation that comes with the <package>menu</package>
6398 package for information about how to register your
6404 <heading>Multimedia handlers</heading>
6407 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6408 is a mechanism for encoding files and data streams and
6409 providing meta-information about them, in particular their
6410 type (e.g. audio or video) and format (e.g. PNG, HTML,
6415 Registration of MIME type handlers allows programs like mail
6416 user agents and web browsers to invoke these handlers to
6417 view, edit or display MIME types they don't support directly.
6421 Packages which provide the ability to view/show/play,
6422 compose, edit or print MIME types should register themselves
6423 as such following the current MIME support policy.
6427 The MIME support policy can be found in the <tt>mime-policy</tt>
6428 files in the <tt>debian-policy</tt> package.
6429 It is also available from the Debian web mirrors at
6430 <tt><url name="/doc/packaging-manuals/mime-policy/"
6431 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6437 <heading>Keyboard configuration</heading>
6440 To achieve a consistent keyboard configuration so that all
6441 applications interpret a keyboard event the same way, all
6442 programs in the Debian distribution must be configured to
6443 comply with the following guidelines.
6447 The following keys must have the specified interpretations:
6450 <tag><tt><--</tt></tag>
6451 <item>delete the character to the left of the cursor</item>
6453 <tag><tt>Delete</tt></tag>
6454 <item>delete the character to the right of the cursor</item>
6456 <tag><tt>Control+H</tt></tag>
6457 <item>emacs: the help prefix</item>
6460 The interpretation of any keyboard events should be
6461 independent of the terminal that is used, be it a virtual
6462 console, an X terminal emulator, an rlogin/telnet session,
6467 The following list explains how the different programs
6468 should be set up to achieve this:
6474 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6478 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6482 X translations are set up to make
6483 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6484 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6485 is the vt220 escape code for the "delete character"
6486 key). This must be done by loading the X resources
6487 using <prgn>xrdb</prgn> on all local X displays, not
6488 using the application defaults, so that the
6489 translation resources used correspond to the
6490 <prgn>xmodmap</prgn> settings.
6494 The Linux console is configured to make
6495 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6496 generate <tt>ESC [ 3 ~</tt>.
6500 X applications are configured so that <tt><</tt>
6501 deletes left, and <tt>Delete</tt> deletes right. Motif
6502 applications already work like this.
6506 Terminals should have <tt>stty erase ^?</tt> .
6510 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6511 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6512 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6516 Emacs is programmed to map <tt>KB_Backspace</tt> or
6517 the <tt>stty erase</tt> character to
6518 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6519 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6520 <tt>^H</tt> to <tt>help</tt> as always.
6524 Other applications use the <tt>stty erase</tt>
6525 character and <tt>kdch1</tt> for the two delete keys,
6526 with ASCII DEL being "delete previous character" and
6527 <tt>kdch1</tt> being "delete character under
6535 This will solve the problem except for the following
6542 Some terminals have a <tt><--</tt> key that cannot
6543 be made to produce anything except <tt>^H</tt>. On
6544 these terminals Emacs help will be unavailable on
6545 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6546 character takes precedence in Emacs, and has been set
6547 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6548 available) can be used instead.
6552 Some operating systems use <tt>^H</tt> for <tt>stty
6553 erase</tt>. However, modern telnet versions and all
6554 rlogin versions propagate <tt>stty</tt> settings, and
6555 almost all UNIX versions honour <tt>stty erase</tt>.
6556 Where the <tt>stty</tt> settings are not propagated
6557 correctly, things can be made to work by using
6558 <tt>stty</tt> manually.
6562 Some systems (including previous Debian versions) use
6563 <prgn>xmodmap</prgn> to arrange for both
6564 <tt><--</tt> and <tt>Delete</tt> to generate
6565 <tt>KB_Delete</tt>. We can change the behavior of
6566 their X clients using the same X resources that we use
6567 to do it for our own clients, or configure our clients
6568 using their resources when things are the other way
6569 around. On displays configured like this
6570 <tt>Delete</tt> will not work, but <tt><--</tt>
6575 Some operating systems have different <tt>kdch1</tt>
6576 settings in their <tt>terminfo</tt> database for
6577 <tt>xterm</tt> and others. On these systems the
6578 <tt>Delete</tt> key will not work correctly when you
6579 log in from a system conforming to our policy, but
6580 <tt><--</tt> will.
6587 <heading>Environment variables</heading>
6590 A program must not depend on environment variables to get
6591 reasonable defaults. (That's because these environment
6592 variables would have to be set in a system-wide
6593 configuration file like <file>/etc/profile</file>, which is not
6594 supported by all shells.)
6598 If a program usually depends on environment variables for its
6599 configuration, the program should be changed to fall back to
6600 a reasonable default configuration if these environment
6601 variables are not present. If this cannot be done easily
6602 (e.g., if the source code of a non-free program is not
6603 available), the program must be replaced by a small
6604 "wrapper" shell script which sets the environment variables
6605 if they are not already defined, and calls the original program.
6609 Here is an example of a wrapper script for this purpose:
6611 <example compact="compact">
6613 BAR=${BAR:-/var/lib/fubar}
6615 exec /usr/lib/foo/foo "$@"
6620 Furthermore, as <file>/etc/profile</file> is a configuration
6621 file of the <prgn>base-files</prgn> package, other packages must
6622 not put any environment variables or other commands into that
6627 <sect id="doc-base">
6628 <heading>Registering Documents using doc-base</heading>
6631 The <package>doc-base</package> package implements a
6632 flexible mechanism for handling and presenting
6633 documentation. The recommended practice is for every Debian
6634 package that provides online documentation (other than just
6635 manual pages) to register these documents with
6636 <package>doc-base</package> by installing a
6637 <package>doc-base</package> control file via the
6638 <prgn/install-docs/ script at installation time and
6639 de-register the manuals again when the package is removed.
6642 Please refer to the documentation that comes with the
6643 <package>doc-base</package> package for information and
6652 <heading>Files</heading>
6655 <heading>Binaries</heading>
6658 Two different packages must not install programs with
6659 different functionality but with the same filenames. (The
6660 case of two programs having the same functionality but
6661 different implementations is handled via "alternatives" or
6662 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6663 <ref id="conflicts"> respectively.) If this case happens,
6664 one of the programs must be renamed. The maintainers should
6665 report this to the <tt>debian-devel</tt> mailing list and
6666 try to find a consensus about which program will have to be
6667 renamed. If a consensus cannot be reached, <em>both</em>
6668 programs must be renamed.
6672 By default, when a package is being built, any binaries
6673 created should include debugging information, as well as
6674 being compiled with optimization. You should also turn on
6675 as many reasonable compilation warnings as possible; this
6676 makes life easier for porters, who can then look at build
6677 logs for possible problems. For the C programming language,
6678 this means the following compilation parameters should be
6680 <example compact="compact">
6682 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6684 INSTALL = install -s # (or use strip on the files in debian/tmp)
6689 Note that by default all installed binaries should be stripped,
6690 either by using the <tt>-s</tt> flag to
6691 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6692 the binaries after they have been copied into
6693 <file>debian/tmp</file> but before the tree is made into a
6698 Although binaries in the build tree should be compiled with
6699 debugging information by default, it can often be difficult to
6700 debug programs if they are also subjected to compiler
6701 optimization. For this reason, it is recommended to support the
6702 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
6703 (see <ref id="debianrules-options">). This variable can contain
6704 several flags to change how a package is compiled and built.
6708 It is up to the package maintainer to decide what
6709 compilation options are best for the package. Certain
6710 binaries (such as computationally-intensive programs) will
6711 function better with certain flags (<tt>-O3</tt>, for
6712 example); feel free to use them. Please use good judgment
6713 here. Don't use flags for the sake of it; only use them
6714 if there is good reason to do so. Feel free to override
6715 the upstream author's ideas about which compilation
6716 options are best: they are often inappropriate for our
6722 <sect id="libraries">
6723 <heading>Libraries</heading>
6726 If the package is <strong>architecture: any</strong>, then
6727 the shared library compilation and linking flags must have
6728 <tt>-fPIC</tt>, or the package shall not build on some of
6729 the supported architectures<footnote>
6731 If you are using GCC, <tt>-fPIC</tt> produces code with
6732 relocatable position independent code, which is required for
6733 most architectures to create a shared library, with i386 and
6734 perhaps some others where non position independent code is
6735 permitted in a shared library.
6738 Position independent code may have a performance penalty,
6739 especially on <tt>i386</tt>. However, in most cases the
6740 speed penalty must be measured against the memory wasted on
6741 the few architectures where non position independent code is
6744 </footnote>. Any exception to this rule must be discussed on
6745 the mailing list <em>debian-devel@lists.debian.org</em>, and
6746 a rough consensus obtained. The reasons for not compiling
6747 with <tt>-fPIC</tt> flag must be recorded in the file
6748 <tt>README.Debian</tt>, and care must be taken to either
6749 restrict the architecture or arrange for <tt>-fPIC</tt> to
6750 be used on architectures where it is required.<footnote>
6752 Some of the reasons why this might be required is if the
6753 library contains hand crafted assembly code that is not
6754 relocatable, the speed penalty is excessive for compute
6755 intensive libs, and similar reasons.
6760 As to the static libraries, the common case is not to have
6761 relocatable code, since there is no benefit, unless in specific
6762 cases; therefore the static version must not be compiled
6763 with the <tt>-fPIC</tt> flag. Any exception to this rule
6764 should be discussed on the mailing list
6765 <em>debian-devel@lists.debian.org</em>, and the reasons for
6766 compiling with the <tt>-fPIC</tt> flag must be recorded in
6767 the file <tt>README.Debian</tt>. <footnote>
6769 Some of the reasons for linking static libraries with
6770 the <tt>-fPIC</tt> flag are if, for example, one needs a
6771 Perl API for a library that is under rapid development,
6772 and has an unstable API, so shared libraries are
6773 pointless at this phase of the library's development. In
6774 that case, since Perl needs a library with relocatable
6775 code, it may make sense to create a static library with
6776 relocatable code. Another reason cited is if you are
6777 distilling various libraries into a common shared
6778 library, like <tt>mklibs</tt> does in the Debian
6784 In other words, if both a shared and a static library is
6785 being built, each source unit (<tt>*.c</tt>, for example,
6786 for C files) will need to be compiled twice, for the normal
6790 You must specify the gcc option <tt>-D_REENTRANT</tt>
6791 when building a library (either static or shared) to make
6792 the library compatible with LinuxThreads.
6796 Although not enforced by the build tools, shared libraries
6797 must be linked against all libraries that they use symbols from
6798 in the same way that binaries are. This ensures the correct
6799 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
6800 system and guarantees that all libraries can be safely opened
6801 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
6802 option <tt>-Wl,-z,defs</tt> when building a shared library.
6803 Since this option enforces symbol resolution at build time,
6804 a missing library reference will be caught early as a fatal
6809 All installed shared libraries should be stripped with
6810 <example compact="compact">
6811 strip --strip-unneeded <var>your-lib</var>
6813 (The option <tt>--strip-unneeded</tt> makes
6814 <prgn>strip</prgn> remove only the symbols which aren't
6815 needed for relocation processing.) Shared libraries can
6816 function perfectly well when stripped, since the symbols for
6817 dynamic linking are in a separate part of the ELF object
6819 You might also want to use the options
6820 <tt>--remove-section=.comment</tt> and
6821 <tt>--remove-section=.note</tt> on both shared libraries
6822 and executables, and <tt>--strip-debug</tt> on static
6828 Note that under some circumstances it may be useful to
6829 install a shared library unstripped, for example when
6830 building a separate package to support debugging.
6834 Shared object files (often <file>.so</file> files) that are not
6835 public libraries, that is, they are not meant to be linked
6836 to by third party executables (binaries of other packages),
6837 should be installed in subdirectories of the
6838 <file>/usr/lib</file> directory. Such files are exempt from the
6839 rules that govern ordinary shared libraries, except that
6840 they must not be installed executable and should be
6842 A common example are the so-called "plug-ins",
6843 internal shared objects that are dynamically loaded by
6844 programs using <manref name="dlopen" section="3">.
6849 Packages containing shared libraries that may be linked to
6850 by other packages' binaries, but which for some
6851 <em>compelling</em> reason can not be installed in
6852 <file>/usr/lib</file> directory, may install the shared library
6853 files in subdirectories of the <file>/usr/lib</file> directory,
6854 in which case they should arrange to add that directory in
6855 <file>/etc/ld.so.conf</file> in the package's post-installation
6856 script, and remove it in the package's post-removal script.
6860 An ever increasing number of packages are using
6861 <prgn>libtool</prgn> to do their linking. The latest GNU
6862 libtools (>= 1.3a) can take advantage of the metadata in the
6863 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
6864 files). The main advantage of <prgn>libtool</prgn>'s
6865 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
6866 store and subsequently access metadata with respect to the
6867 libraries it builds. <prgn>libtool</prgn> will search for
6868 those files, which contain a lot of useful information about
6869 a library (such as library dependency information for static
6870 linking). Also, they're <em>essential</em> for programs
6871 using <tt>libltdl</tt>.<footnote>
6872 Although <prgn>libtool</prgn> is fully capable of
6873 linking against shared libraries which don't have
6874 <tt>.la</tt> files, as it is a mere shell script it can
6875 add considerably to the build time of a
6876 <prgn>libtool</prgn>-using package if that shell script
6877 has to derive all this information from first principles
6878 for each library every time it is linked. With the
6879 advent of <prgn>libtool</prgn> version 1.4 (and to a
6880 lesser extent <prgn>libtool</prgn> version 1.3), the
6881 <file>.la</file> files also store information about
6882 inter-library dependencies which cannot necessarily be
6883 derived after the <file>.la</file> file is deleted.
6888 Packages that use <prgn>libtool</prgn> to create shared
6889 libraries should include the <file>.la</file> files in the
6890 <tt>-dev</tt> package, unless the package relies on
6891 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
6892 the <tt>.la</tt> files must go in the run-time library
6897 You must make sure that you use only released versions of
6898 shared libraries to build your packages; otherwise other
6899 users will not be able to run your binaries
6900 properly. Producing source packages that depend on
6901 unreleased compilers is also usually a bad
6908 <heading>Shared libraries</heading>
6910 This section has moved to <ref id="sharedlibs">.
6916 <heading>Scripts</heading>
6919 All command scripts, including the package maintainer
6920 scripts inside the package and used by <prgn>dpkg</prgn>,
6921 should have a <tt>#!</tt> line naming the shell to be used
6926 In the case of Perl scripts this should be
6927 <tt>#!/usr/bin/perl</tt>.
6931 When scripts are installed into a directory in the system
6932 PATH, the script name should not include an extension such
6933 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
6934 language currently used to implement it.
6937 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
6938 should almost certainly start with <tt>set -e</tt> so that
6939 errors are detected. Every script should use
6940 <tt>set -e</tt> or check the exit status of <em>every</em>
6945 Scripts may assume that <file>/bin/sh</file> implements the
6946 SUSv3 Shell Command Language<footnote>
6947 Single UNIX Specification, version 3, which is also IEEE
6948 1003.1-2004 (POSIX), and is available on the World Wide Web
6949 from <url id="http://www.unix.org/version3/online.html"
6950 name="The Open Group"> after free
6951 registration.</footnote>
6952 plus the following additional features not mandated by
6954 These features are in widespread use in the Linux community
6955 and are implemented in all of bash, dash, and ksh, the most
6956 common shells users may wish to use as <file>/bin/sh</file>.
6959 <item><tt>echo -n</tt>, if implemented as a shell built-in,
6960 must not generate a newline.</item>
6961 <item><tt>test</tt>, if implemented as a shell built-in, must
6962 support <tt>-a</tt> and <tt>-o</tt> as binary logical
6964 <item><tt>local</tt> to create a scoped variable must be
6965 supported; however, <tt>local</tt> may or may not preserve
6966 the variable value from an outer scope and may or may not
6967 support arguments more complex than simple variables. Only
6979 If a shell script requires non-SUSv3 features from the shell
6980 interpreter other than those listed above, the appropriate shell
6981 must be specified in the first line of the script (e.g.,
6982 <tt>#!/bin/bash</tt>) and the package must depend on the package
6983 providing the shell (unless the shell package is marked
6984 "Essential", as in the case of <prgn>bash</prgn>).
6988 You may wish to restrict your script to SUSv3 features plus the
6989 above set when possible so that it may use <file>/bin/sh</file>
6990 as its interpreter. If your script works with <prgn>dash</prgn>
6991 (originally called <prgn>ash</prgn>), it probably complies with
6992 the above requirements, but if you are in doubt, use
6993 <file>/bin/bash</file>.
6997 Perl scripts should check for errors when making any
6998 system calls, including <tt>open</tt>, <tt>print</tt>,
6999 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7003 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7004 scripting languages. See <em>Csh Programming Considered
7005 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7006 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7007 If an upstream package comes with <prgn>csh</prgn> scripts
7008 then you must make sure that they start with
7009 <tt>#!/bin/csh</tt> and make your package depend on the
7010 <prgn>c-shell</prgn> virtual package.
7014 Any scripts which create files in world-writeable
7015 directories (e.g., in <file>/tmp</file>) must use a
7016 mechanism which will fail atomically if a file with the same
7017 name already exists.
7021 The Debian base system provides the <prgn>tempfile</prgn>
7022 and <prgn>mktemp</prgn> utilities for use by scripts for
7029 <heading>Symbolic links</heading>
7032 In general, symbolic links within a top-level directory
7033 should be relative, and symbolic links pointing from one
7034 top-level directory into another should be absolute. (A
7035 top-level directory is a sub-directory of the root
7036 directory <file>/</file>.)
7040 In addition, symbolic links should be specified as short as
7041 possible, i.e., link targets like <file>foo/../bar</file> are
7046 Note that when creating a relative link using
7047 <prgn>ln</prgn> it is not necessary for the target of the
7048 link to exist relative to the working directory you're
7049 running <prgn>ln</prgn> from, nor is it necessary to change
7050 directory to the directory where the link is to be made.
7051 Simply include the string that should appear as the target
7052 of the link (this will be a pathname relative to the
7053 directory in which the link resides) as the first argument
7058 For example, in your <prgn>Makefile</prgn> or
7059 <file>debian/rules</file>, you can do things like:
7060 <example compact="compact">
7061 ln -fs gcc $(prefix)/bin/cc
7062 ln -fs gcc debian/tmp/usr/bin/cc
7063 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7064 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7069 A symbolic link pointing to a compressed file should always
7070 have the same file extension as the referenced file. (For
7071 example, if a file <file>foo.gz</file> is referenced by a
7072 symbolic link, the filename of the link has to end with
7073 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7078 <heading>Device files</heading>
7081 Packages must not include device files in the package file
7086 If a package needs any special device files that are not
7087 included in the base system, it must call
7088 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7089 after notifying the user<footnote>
7090 This notification could be done via a (low-priority)
7091 debconf message, or an echo (printf) statement.
7096 Packages must not remove any device files in the
7097 <prgn>postrm</prgn> or any other script. This is left to the
7098 system administrator.
7102 Debian uses the serial devices
7103 <file>/dev/ttyS*</file>. Programs using the old
7104 <file>/dev/cu*</file> devices should be changed to use
7105 <file>/dev/ttyS*</file>.
7109 <sect id="config-files">
7110 <heading>Configuration files</heading>
7113 <heading>Definitions</heading>
7117 <tag>configuration file</tag>
7119 A file that affects the operation of a program, or
7120 provides site- or host-specific information, or
7121 otherwise customizes the behavior of a program.
7122 Typically, configuration files are intended to be
7123 modified by the system administrator (if needed or
7124 desired) to conform to local policy or to provide
7125 more useful site-specific behavior.
7128 <tag><tt>conffile</tt></tag>
7130 A file listed in a package's <tt>conffiles</tt>
7131 file, and is treated specially by <prgn>dpkg</prgn>
7132 (see <ref id="configdetails">).
7138 The distinction between these two is important; they are
7139 not interchangeable concepts. Almost all
7140 <tt>conffile</tt>s are configuration files, but many
7141 configuration files are not <tt>conffiles</tt>.
7145 Note that a script that embeds configuration information
7146 (such as most of the files in <file>/etc/default</file> and
7147 <file>/etc/cron.{daily,weekly,monthly}</file>) is de-facto a
7148 configuration file and should be treated as such.
7153 <heading>Location</heading>
7156 Any configuration files created or used by your package
7157 must reside in <file>/etc</file>. If there are several,
7158 consider creating a subdirectory of <file>/etc</file>
7159 named after your package.
7163 If your package creates or uses configuration files
7164 outside of <file>/etc</file>, and it is not feasible to modify
7165 the package to use <file>/etc</file> directly, put the files
7166 in <file>/etc</file> and create symbolic links to those files
7167 from the location that the package requires.
7172 <heading>Behavior</heading>
7175 Configuration file handling must conform to the following
7177 <list compact="compact">
7179 local changes must be preserved during a package
7183 configuration files must be preserved when the
7184 package is removed, and only deleted when the
7191 The easy way to achieve this behavior is to make the
7192 configuration file a <tt>conffile</tt>. This is
7193 appropriate only if it is possible to distribute a default
7194 version that will work for most installations, although
7195 some system administrators may choose to modify it. This
7196 implies that the default version will be part of the
7197 package distribution, and must not be modified by the
7198 maintainer scripts during installation (or at any other
7203 In order to ensure that local changes are preserved
7204 correctly, no package may contain or make hard links to
7205 conffiles.<footnote>
7206 Rationale: There are two problems with hard links.
7207 The first is that some editors break the link while
7208 editing one of the files, so that the two files may
7209 unwittingly become unlinked and different. The second
7210 is that <prgn>dpkg</prgn> might break the hard link
7211 while upgrading <tt>conffile</tt>s.
7216 The other way to do it is via the maintainer scripts. In
7217 this case, the configuration file must not be listed as a
7218 <tt>conffile</tt> and must not be part of the package
7219 distribution. If the existence of a file is required for
7220 the package to be sensibly configured it is the
7221 responsibility of the package maintainer to provide
7222 maintainer scripts which correctly create, update and
7223 maintain the file and remove it on purge. (See <ref
7224 id="maintainerscripts"> for more information.) These
7225 scripts must be idempotent (i.e., must work correctly if
7226 <prgn>dpkg</prgn> needs to re-run them due to errors
7227 during installation or removal), must cope with all the
7228 variety of ways <prgn>dpkg</prgn> can call maintainer
7229 scripts, must not overwrite or otherwise mangle the user's
7230 configuration without asking, must not ask unnecessary
7231 questions (particularly during upgrades), and must
7232 otherwise be good citizens.
7236 The scripts are not required to configure every possible
7237 option for the package, but only those necessary to get
7238 the package running on a given system. Ideally the
7239 sysadmin should not have to do any configuration other
7240 than that done (semi-)automatically by the
7241 <prgn>postinst</prgn> script.
7245 A common practice is to create a script called
7246 <file><var>package</var>-configure</file> and have the
7247 package's <prgn>postinst</prgn> call it if and only if the
7248 configuration file does not already exist. In certain
7249 cases it is useful for there to be an example or template
7250 file which the maintainer scripts use. Such files should
7251 be in <file>/usr/share/<var>package</var></file> or
7252 <file>/usr/lib/<var>package</var></file> (depending on whether
7253 they are architecture-independent or not). There should
7254 be symbolic links to them from
7255 <file>/usr/share/doc/<var>package</var>/examples</file> if
7256 they are examples, and should be perfectly ordinary
7257 <prgn>dpkg</prgn>-handled files (<em>not</em>
7258 configuration files).
7262 These two styles of configuration file handling must
7263 not be mixed, for that way lies madness:
7264 <prgn>dpkg</prgn> will ask about overwriting the file
7265 every time the package is upgraded.
7270 <heading>Sharing configuration files</heading>
7273 Packages which specify the same file as a
7274 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7275 with each other. (This is an instance of the general rule
7276 about not sharing files. Note that neither alternatives
7277 nor diversions are likely to be appropriate in this case;
7278 in particular, <prgn>dpkg</prgn> does not handle diverted
7279 <tt>conffile</tt>s well.)
7283 The maintainer scripts must not alter a <tt>conffile</tt>
7284 of <em>any</em> package, including the one the scripts
7289 If two or more packages use the same configuration file
7290 and it is reasonable for both to be installed at the same
7291 time, one of these packages must be defined as
7292 <em>owner</em> of the configuration file, i.e., it will be
7293 the package which handles that file as a configuration
7294 file. Other packages that use the configuration file must
7295 depend on the owning package if they require the
7296 configuration file to operate. If the other package will
7297 use the configuration file if present, but is capable of
7298 operating without it, no dependency need be declared.
7302 If it is desirable for two or more related packages to
7303 share a configuration file <em>and</em> for all of the
7304 related packages to be able to modify that configuration
7305 file, then the following should be done:
7306 <enumlist compact="compact">
7308 One of the related packages (the "owning" package)
7309 will manage the configuration file with maintainer
7310 scripts as described in the previous section.
7313 The owning package should also provide a program
7314 that the other packages may use to modify the
7318 The related packages must use the provided program
7319 to make any desired modifications to the
7320 configuration file. They should either depend on
7321 the core package to guarantee that the configuration
7322 modifier program is available or accept gracefully
7323 that they cannot modify the configuration file if it
7324 is not. (This is in addition to the fact that the
7325 configuration file may not even be present in the
7332 Sometimes it's appropriate to create a new package which
7333 provides the basic infrastructure for the other packages
7334 and which manages the shared configuration files. (The
7335 <tt>sgml-base</tt> package is a good example.)
7340 <heading>User configuration files ("dotfiles")</heading>
7343 The files in <file>/etc/skel</file> will automatically be
7344 copied into new user accounts by <prgn>adduser</prgn>.
7345 No other program should reference the files in
7346 <file>/etc/skel</file>.
7350 Therefore, if a program needs a dotfile to exist in
7351 advance in <file>$HOME</file> to work sensibly, that dotfile
7352 should be installed in <file>/etc/skel</file> and treated as a
7357 However, programs that require dotfiles in order to
7358 operate sensibly are a bad thing, unless they do create
7359 the dotfiles themselves automatically.
7363 Furthermore, programs should be configured by the Debian
7364 default installation to behave as closely to the upstream
7365 default behavior as possible.
7369 Therefore, if a program in a Debian package needs to be
7370 configured in some way in order to operate sensibly, that
7371 should be done using a site-wide configuration file placed
7372 in <file>/etc</file>. Only if the program doesn't support a
7373 site-wide default configuration and the package maintainer
7374 doesn't have time to add it may a default per-user file be
7375 placed in <file>/etc/skel</file>.
7379 <file>/etc/skel</file> should be as empty as we can make it.
7380 This is particularly true because there is no easy (or
7381 necessarily desirable) mechanism for ensuring that the
7382 appropriate dotfiles are copied into the accounts of
7383 existing users when a package is installed.
7389 <heading>Log files</heading>
7391 Log files should usually be named
7392 <file>/var/log/<var>package</var>.log</file>. If you have many
7393 log files, or need a separate directory for permission
7394 reasons (<file>/var/log</file> is writable only by
7395 <file>root</file>), you should usually create a directory named
7396 <file>/var/log/<var>package</var></file> and place your log
7401 Log files must be rotated occasionally so that they don't
7402 grow indefinitely; the best way to do this is to drop a log
7403 rotation configuration file into the directory
7404 <file>/etc/logrotate.d</file> and use the facilities provided by
7405 logrotate.<footnote>
7407 The traditional approach to log files has been to set up
7408 <em>ad hoc</em> log rotation schemes using simple shell
7409 scripts and cron. While this approach is highly
7410 customizable, it requires quite a lot of sysadmin work.
7411 Even though the original Debian system helped a little
7412 by automatically installing a system which can be used
7413 as a template, this was deemed not enough.
7417 The use of <prgn>logrotate</prgn>, a program developed
7418 by Red Hat, is better, as it centralizes log management.
7419 It has both a configuration file
7420 (<file>/etc/logrotate.conf</file>) and a directory where
7421 packages can drop their individual log rotation
7422 configurations (<file>/etc/logrotate.d</file>).
7425 Here is a good example for a logrotate config
7426 file (for more information see <manref name="logrotate"
7428 <example compact="compact">
7429 /var/log/foo/*.log {
7434 /etc/init.d/foo force-reload
7438 This rotates all files under <file>/var/log/foo</file>, saves 12
7439 compressed generations, and forces the daemon to reload its
7440 configuration information after the log rotation.
7444 Log files should be removed when the package is
7445 purged (but not when it is only removed). This should be
7446 done by the <prgn>postrm</prgn> script when it is called
7447 with the argument <tt>purge</tt> (see <ref
7448 id="removedetails">).
7453 <heading>Permissions and owners</heading>
7456 The rules in this section are guidelines for general use.
7457 If necessary you may deviate from the details below.
7458 However, if you do so you must make sure that what is done
7459 is secure and you should try to be as consistent as possible
7460 with the rest of the system. You should probably also
7461 discuss it on <prgn>debian-devel</prgn> first.
7465 Files should be owned by <tt>root.root</tt>, and made
7466 writable only by the owner and universally readable (and
7467 executable, if appropriate), that is mode 644 or 755.
7471 Directories should be mode 755 or (for group-writability)
7472 mode 2775. The ownership of the directory should be
7473 consistent with its mode: if a directory is mode 2775, it
7474 should be owned by the group that needs write access to
7477 When a package is upgraded, and the owner or permissions
7478 of a file included in the package has changed, dpkg
7479 arranges for the ownership and permissions to be
7480 correctly set upon installation. However, this does not
7481 extend to directories; the permissions and ownership of
7482 directories already on the system does not change on
7483 install or upgrade of packages. This makes sense, since
7484 otherwise common directories like <tt>/usr</tt> would
7485 always be in flux. To correctly change permissions of a
7486 directory the package owns, explicit action is required,
7487 usually in the <tt>postinst</tt> script. Care must be
7488 taken to handle downgrades as well, in that case.
7495 Setuid and setgid executables should be mode 4755 or 2755
7496 respectively, and owned by the appropriate user or group.
7497 They should not be made unreadable (modes like 4711 or
7498 2711 or even 4111); doing so achieves no extra security,
7499 because anyone can find the binary in the freely available
7500 Debian package; it is merely inconvenient. For the same
7501 reason you should not restrict read or execute permissions
7502 on non-set-id executables.
7506 Some setuid programs need to be restricted to particular
7507 sets of users, using file permissions. In this case they
7508 should be owned by the uid to which they are set-id, and by
7509 the group which should be allowed to execute them. They
7510 should have mode 4754; again there is no point in making
7511 them unreadable to those users who must not be allowed to
7516 It is possible to arrange that the system administrator can
7517 reconfigure the package to correspond to their local
7518 security policy by changing the permissions on a binary:
7519 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7520 described below.<footnote>
7521 Ordinary files installed by <prgn>dpkg</prgn> (as
7522 opposed to <tt>conffile</tt>s and other similar objects)
7523 normally have their permissions reset to the distributed
7524 permissions when the package is reinstalled. However,
7525 the use of <prgn>dpkg-statoverride</prgn> overrides this
7526 default behavior. If you use this method, you should
7527 remember to describe <prgn>dpkg-statoverride</prgn> in
7528 the package documentation; being a relatively new
7529 addition to Debian, it is probably not yet well-known.
7531 Another method you should consider is to create a group for
7532 people allowed to use the program(s) and make any setuid
7533 executables executable only by that group.
7537 If you need to create a new user or group for your package
7538 there are two possibilities. Firstly, you may need to
7539 make some files in the binary package be owned by this
7540 user or group, or you may need to compile the user or
7541 group id (rather than just the name) into the binary
7542 (though this latter should be avoided if possible, as in
7543 this case you need a statically allocated id).</p>
7546 If you need a statically allocated id, you must ask for a
7547 user or group id from the <tt>base-passwd</tt> maintainer,
7548 and must not release the package until you have been
7549 allocated one. Once you have been allocated one you must
7550 either make the package depend on a version of the
7551 <tt>base-passwd</tt> package with the id present in
7552 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7553 your package to create the user or group itself with the
7554 correct id (using <tt>adduser</tt>) in its
7555 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7556 the <prgn>postinst</prgn> is to be preferred if it is
7557 possible, otherwise a pre-dependency will be needed on the
7558 <tt>adduser</tt> package.)
7562 On the other hand, the program might be able to determine
7563 the uid or gid from the user or group name at runtime, so
7564 that a dynamically allocated id can be used. In this case
7565 you should choose an appropriate user or group name,
7566 discussing this on <prgn>debian-devel</prgn> and checking
7567 with the <package/base-passwd/ maintainer that it is unique and that
7568 they do not wish you to use a statically allocated id
7569 instead. When this has been checked you must arrange for
7570 your package to create the user or group if necessary using
7571 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7572 <prgn>postinst</prgn> script (again, the latter is to be
7573 preferred if it is possible).
7577 Note that changing the numeric value of an id associated
7578 with a name is very difficult, and involves searching the
7579 file system for all appropriate files. You need to think
7580 carefully whether a static or dynamic id is required, since
7581 changing your mind later will cause problems.
7584 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7586 This section is not intended as policy, but as a
7587 description of the use of <prgn>dpkg-statoverride</prgn>.
7591 If a system administrator wishes to have a file (or
7592 directory or other such thing) installed with owner and
7593 permissions different from those in the distributed Debian
7594 package, they can use the <prgn>dpkg-statoverride</prgn>
7595 program to instruct <prgn>dpkg</prgn> to use the different
7596 settings every time the file is installed. Thus the
7597 package maintainer should distribute the files with their
7598 normal permissions, and leave it for the system
7599 administrator to make any desired changes. For example, a
7600 daemon which is normally required to be setuid root, but
7601 in certain situations could be used without being setuid,
7602 should be installed setuid in the <tt>.deb</tt>. Then the
7603 local system administrator can change this if they wish.
7604 If there are two standard ways of doing it, the package
7605 maintainer can use <tt>debconf</tt> to find out the
7606 preference, and call <prgn>dpkg-statoverride</prgn> in the
7607 maintainer script if necessary to accommodate the system
7608 administrator's choice. Care must be taken during
7609 upgrades to not override an existing setting.
7613 Given the above, <prgn>dpkg-statoverride</prgn> is
7614 essentially a tool for system administrators and would not
7615 normally be needed in the maintainer scripts. There is
7616 one type of situation, though, where calls to
7617 <prgn>dpkg-statoverride</prgn> would be needed in the
7618 maintainer scripts, and that involves packages which use
7619 dynamically allocated user or group ids. In such a
7620 situation, something like the following idiom can be very
7621 helpful in the package's <prgn>postinst</prgn>, where
7622 <tt>sysuser</tt> is a dynamically allocated id:
7624 for i in /usr/bin/foo /usr/sbin/bar
7626 # only do something when no setting exists
7627 if ! dpkg-statoverride --list $i >/dev/null 2>&1
7629 #include: debconf processing, question about foo and bar
7630 if [ "$RET" = "true" ] ; then
7631 dpkg-statoverride --update --add sysuser root 4755 $i
7636 The corresponding <tt>dpkg-statoverride --remove</tt>
7637 calls can then be made unconditionally when the package is
7645 <chapt id="customized-programs">
7646 <heading>Customized programs</heading>
7648 <sect id="arch-spec">
7649 <heading>Architecture specification strings</heading>
7652 If a program needs to specify an <em>architecture specification
7653 string</em> in some place, it should select one of the
7654 strings provided by <tt>dpkg-architecture -L</tt>. The
7655 strings are in the format
7656 <tt><var>os</var>-<var>arch</var></tt>, though the OS part
7657 is sometimes elided, as when the OS is Linux.<footnote>
7658 <p>Currently, the strings are:
7659 i386 ia64 alpha amd64 armeb arm hppa m32r m68k mips
7660 mipsel powerpc ppc64 s390 s390x sh3 sh3eb sh4 sh4eb
7661 sparc darwin-i386 darwin-ia64 darwin-alpha darwin-amd64
7662 darwin-armeb darwin-arm darwin-hppa darwin-m32r
7663 darwin-m68k darwin-mips darwin-mipsel darwin-powerpc
7664 darwin-ppc64 darwin-s390 darwin-s390x darwin-sh3
7665 darwin-sh3eb darwin-sh4 darwin-sh4eb darwin-sparc
7666 freebsd-i386 freebsd-ia64 freebsd-alpha freebsd-amd64
7667 freebsd-armeb freebsd-arm freebsd-hppa freebsd-m32r
7668 freebsd-m68k freebsd-mips freebsd-mipsel freebsd-powerpc
7669 freebsd-ppc64 freebsd-s390 freebsd-s390x freebsd-sh3
7670 freebsd-sh3eb freebsd-sh4 freebsd-sh4eb freebsd-sparc
7671 kfreebsd-i386 kfreebsd-ia64 kfreebsd-alpha
7672 kfreebsd-amd64 kfreebsd-armeb kfreebsd-arm kfreebsd-hppa
7673 kfreebsd-m32r kfreebsd-m68k kfreebsd-mips
7674 kfreebsd-mipsel kfreebsd-powerpc kfreebsd-ppc64
7675 kfreebsd-s390 kfreebsd-s390x kfreebsd-sh3 kfreebsd-sh3eb
7676 kfreebsd-sh4 kfreebsd-sh4eb kfreebsd-sparc knetbsd-i386
7677 knetbsd-ia64 knetbsd-alpha knetbsd-amd64 knetbsd-armeb
7678 knetbsd-arm knetbsd-hppa knetbsd-m32r knetbsd-m68k
7679 knetbsd-mips knetbsd-mipsel knetbsd-powerpc
7680 knetbsd-ppc64 knetbsd-s390 knetbsd-s390x knetbsd-sh3
7681 knetbsd-sh3eb knetbsd-sh4 knetbsd-sh4eb knetbsd-sparc
7682 netbsd-i386 netbsd-ia64 netbsd-alpha netbsd-amd64
7683 netbsd-armeb netbsd-arm netbsd-hppa netbsd-m32r
7684 netbsd-m68k netbsd-mips netbsd-mipsel netbsd-powerpc
7685 netbsd-ppc64 netbsd-s390 netbsd-s390x netbsd-sh3
7686 netbsd-sh3eb netbsd-sh4 netbsd-sh4eb netbsd-sparc
7687 openbsd-i386 openbsd-ia64 openbsd-alpha openbsd-amd64
7688 openbsd-armeb openbsd-arm openbsd-hppa openbsd-m32r
7689 openbsd-m68k openbsd-mips openbsd-mipsel openbsd-powerpc
7690 openbsd-ppc64 openbsd-s390 openbsd-s390x openbsd-sh3
7691 openbsd-sh3eb openbsd-sh4 openbsd-sh4eb openbsd-sparc
7692 hurd-i386 hurd-ia64 hurd-alpha hurd-amd64 hurd-armeb
7693 hurd-arm hurd-hppa hurd-m32r hurd-m68k hurd-mips
7694 hurd-mipsel hurd-powerpc hurd-ppc64 hurd-s390 hurd-s390x
7695 hurd-sh3 hurd-sh3eb hurd-sh4 hurd-sh4eb hurd-sparc
7701 Note that we don't want to use
7702 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7703 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7704 since this would make our programs incompatible with other
7705 Linux distributions. We also don't use something like
7706 <tt><var>arch</var>-unknown-linux</tt>, since the
7707 <tt>unknown</tt> does not look very good.
7712 <heading>Daemons</heading>
7715 The configuration files <file>/etc/services</file>,
7716 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7717 by the <prgn>netbase</prgn> package and must not be modified
7722 If a package requires a new entry in one of these files, the
7723 maintainer should get in contact with the
7724 <prgn>netbase</prgn> maintainer, who will add the entries
7725 and release a new version of the <prgn>netbase</prgn>
7730 The configuration file <file>/etc/inetd.conf</file> must not be
7731 modified by the package's scripts except via the
7732 <prgn>update-inetd</prgn> script or the
7733 <file>DebianNet.pm</file> Perl module. See their documentation
7734 for details on how to add entries.
7738 If a package wants to install an example entry into
7739 <file>/etc/inetd.conf</file>, the entry must be preceded with
7740 exactly one hash character (<tt>#</tt>). Such lines are
7741 treated as "commented out by user" by the
7742 <prgn>update-inetd</prgn> script and are not changed or
7743 activated during package updates.
7748 <heading>Using pseudo-ttys and modifying wtmp, utmp and
7752 Some programs need to create pseudo-ttys. This should be done
7753 using Unix98 ptys if the C library supports it. The resulting
7754 program must not be installed setuid root, unless that
7755 is required for other functionality.
7759 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
7760 <file>/var/log/lastlog</file> must be installed writable by
7761 group <tt>utmp</tt>. Programs which need to modify those
7762 files must be installed setgid <tt>utmp</tt>.
7767 <heading>Editors and pagers</heading>
7770 Some programs have the ability to launch an editor or pager
7771 program to edit or display a text document. Since there are
7772 lots of different editors and pagers available in the Debian
7773 distribution, the system administrator and each user should
7774 have the possibility to choose their preferred editor and
7779 In addition, every program should choose a good default
7780 editor/pager if none is selected by the user or system
7785 Thus, every program that launches an editor or pager must
7786 use the EDITOR or PAGER environment variable to determine
7787 the editor or pager the user wishes to use. If these
7788 variables are not set, the programs <file>/usr/bin/editor</file>
7789 and <file>/usr/bin/pager</file> should be used, respectively.
7793 These two files are managed through the <prgn>dpkg</prgn>
7794 "alternatives" mechanism. Thus every package providing an
7795 editor or pager must call the
7796 <prgn>update-alternatives</prgn> script to register these
7801 If it is very hard to adapt a program to make use of the
7802 EDITOR or PAGER variables, that program may be configured to
7803 use <file>/usr/bin/sensible-editor</file> and
7804 <file>/usr/bin/sensible-pager</file> as the editor or pager
7805 program respectively. These are two scripts provided in the
7806 Debian base system that check the EDITOR and PAGER variables
7807 and launch the appropriate program, and fall back to
7808 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
7809 variable is not set.
7813 A program may also use the VISUAL environment variable to
7814 determine the user's choice of editor. If it exists, it
7815 should take precedence over EDITOR. This is in fact what
7816 <file>/usr/bin/sensible-editor</file> does.
7820 It is not required for a package to depend on
7821 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
7822 package to provide such virtual packages.<footnote>
7823 The Debian base system already provides an editor and a
7829 <sect id="web-appl">
7830 <heading>Web servers and applications</heading>
7833 This section describes the locations and URLs that should
7834 be used by all web servers and web applications in the
7841 Cgi-bin executable files are installed in the
7843 <example compact="compact">
7844 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
7846 and should be referred to as
7847 <example compact="compact">
7848 http://localhost/cgi-bin/<var>cgi-bin-name</var>
7854 <p>Access to HTML documents</p>
7857 HTML documents for a package are stored in
7858 <file>/usr/share/doc/<var>package</var></file>
7859 and can be referred to as
7860 <example compact="compact">
7861 http://localhost/doc/<var>package</var>/<var>filename</var>
7866 The web server should restrict access to the document
7867 tree so that only clients on the same host can read
7868 the documents. If the web server does not support such
7869 access controls, then it should not provide access at
7870 all, or ask about providing access during installation.
7875 <p>Access to images</p>
7877 It is recommended that images for a package be stored
7878 in <tt>/usr/share/images/<var>package</var></tt> and
7879 may be referred to through an alias <tt>/images/</tt>
7882 http://localhost/images/<package>/<filename>
7889 <p>Web Document Root</p>
7892 Web Applications should try to avoid storing files in
7893 the Web Document Root. Instead they should use the
7894 /usr/share/doc/<var>package</var> directory for
7895 documents and register the Web Application via the
7896 <package>doc-base</package> package. If access to the
7897 web document root is unavoidable then use
7898 <example compact="compact">
7901 as the Document Root. This might be just a symbolic
7902 link to the location where the system administrator
7903 has put the real document root.
7906 <item><p>Providing httpd and/or httpd-cgi</p>
7908 All web servers should provide the virtual package
7909 <tt>httpd</tt>. If a web server has CGI support it should
7910 provide <tt>httpd-cgi</tt> additionally.
7913 All web applications which do not contain CGI scripts should
7914 depend on <tt>httpd</tt>, all those web applications which
7915 <tt>do</tt> contain CGI scripts, should depend on
7923 <sect id="mail-transport-agents">
7924 <heading>Mail transport, delivery and user agents</heading>
7927 Debian packages which process electronic mail, whether mail
7928 user agents (MUAs) or mail transport agents (MTAs), must
7929 ensure that they are compatible with the configuration
7930 decisions below. Failure to do this may result in lost
7931 mail, broken <tt>From:</tt> lines, and other serious brain
7936 The mail spool is <file>/var/mail</file> and the interface to
7937 send a mail message is <file>/usr/sbin/sendmail</file> (as per
7938 the FHS). On older systems, the mail spool may be
7939 physically located in <file>/var/spool/mail</file>, but all
7940 access to the mail spool should be via the
7941 <file>/var/mail</file> symlink. The mail spool is part of the
7942 base system and not part of the MTA package.
7946 All Debian MUAs, MTAs, MDAs and other mailbox accessing
7947 programs (such as IMAP daemons) must lock the mailbox in an
7948 NFS-safe way. This means that <tt>fcntl()</tt> locking must
7949 be combined with dot locking. To avoid deadlocks, a program
7950 should use <tt>fcntl()</tt> first and dot locking after
7951 this, or alternatively implement the two locking methods in
7952 a non blocking way<footnote>
7953 If it is not possible to establish both locks, the
7954 system shouldn't wait for the second lock to be
7955 established, but remove the first lock, wait a (random)
7956 time, and start over locking again.
7957 </footnote>. Using the functions <tt>maillock</tt> and
7958 <tt>mailunlock</tt> provided by the
7959 <tt>liblockfile*</tt><footnote>
7960 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
7961 to use these functions.
7962 </footnote> packages is the recommended way to realize this.
7966 Mailboxes are generally mode 660
7967 <tt><var>user</var>.mail</tt> unless the system
7968 administrator has chosen otherwise. A MUA may remove a
7969 mailbox (unless it has nonstandard permissions) in which
7970 case the MTA or another MUA must recreate it if needed.
7971 Mailboxes must be writable by group mail.
7975 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
7976 be setgid mail to do the locking mentioned above (and
7977 must obviously avoid accessing other users' mailboxes
7978 using this privilege).</p>
7981 <file>/etc/aliases</file> is the source file for the system mail
7982 aliases (e.g., postmaster, usenet, etc.), it is the one
7983 which the sysadmin and <prgn>postinst</prgn> scripts may
7984 edit. After <file>/etc/aliases</file> is edited the program or
7985 human editing it must call <prgn>newaliases</prgn>. All MTA
7986 packages must come with a <prgn>newaliases</prgn> program,
7987 even if it does nothing, but older MTA packages did not do
7988 this so programs should not fail if <prgn>newaliases</prgn>
7989 cannot be found. Note that because of this, all MTA
7990 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
7991 <tt>Replaces: mail-transport-agent</tt> control file
7996 The convention of writing <tt>forward to
7997 <var>address</var></tt> in the mailbox itself is not
7998 supported. Use a <tt>.forward</tt> file instead.</p>
8001 The <prgn>rmail</prgn> program used by UUCP
8002 for incoming mail should be <file>/usr/sbin/rmail</file>.
8003 Likewise, <prgn>rsmtp</prgn>, for receiving
8004 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8008 If your package needs to know what hostname to use on (for
8009 example) outgoing news and mail messages which are generated
8010 locally, you should use the file <file>/etc/mailname</file>. It
8011 will contain the portion after the username and <tt>@</tt>
8012 (at) sign for email addresses of users on the machine
8013 (followed by a newline).
8017 Such a package should check for the existence of this file
8018 when it is being configured. If it exists, it should be
8019 used without comment, although an MTA's configuration script
8020 may wish to prompt the user even if it finds that this file
8021 exists. If the file does not exist, the package should
8022 prompt the user for the value (preferably using
8023 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8024 as well as using it in the package's configuration. The
8025 prompt should make it clear that the name will not just be
8026 used by that package. For example, in this situation the
8027 <tt>inn</tt> package could say something like:
8028 <example compact="compact">
8029 Please enter the "mail name" of your system. This is the
8030 hostname portion of the address to be shown on outgoing
8031 news and mail messages. The default is
8032 <var>syshostname</var>, your system's host name. Mail
8033 name ["<var>syshostname</var>"]:
8035 where <var>syshostname</var> is the output of <tt>hostname
8041 <heading>News system configuration</heading>
8044 All the configuration files related to the NNTP (news)
8045 servers and clients should be located under
8046 <file>/etc/news</file>.</p>
8049 There are some configuration issues that apply to a number
8050 of news clients and server packages on the machine. These
8054 <tag><file>/etc/news/organization</file></tag>
8056 A string which should appear as the
8057 organization header for all messages posted
8058 by NNTP clients on the machine
8061 <tag><file>/etc/news/server</file></tag>
8063 Contains the FQDN of the upstream NNTP
8064 server, or localhost if the local machine is
8069 Other global files may be added as required for cross-package news
8076 <heading>Programs for the X Window System</heading>
8079 <heading>Providing X support and package priorities</heading>
8082 Programs that can be configured with support for the X
8083 Window System must be configured to do so and must declare
8084 any package dependencies necessary to satisfy their
8085 runtime requirements when using the X Window System. If
8086 such a package is of higher priority than the X packages
8087 on which it depends, it is required that either the
8088 X-specific components be split into a separate package, or
8089 that an alternative version of the package, which includes
8090 X support, be provided, or that the package's priority be
8096 <heading>Packages providing an X server</heading>
8099 Packages that provide an X server that, directly or
8100 indirectly, communicates with real input and display
8101 hardware should declare in their control data that they
8102 provide the virtual package <tt>xserver</tt>.<footnote>
8103 This implements current practice, and provides an
8104 actual policy for usage of the <tt>xserver</tt>
8105 virtual package which appears in the virtual packages
8106 list. In a nutshell, X servers that interface
8107 directly with the display and input hardware or via
8108 another subsystem (e.g., GGI) should provide
8109 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8110 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8116 <heading>Packages providing a terminal emulator</heading>
8119 Packages that provide a terminal emulator for the X Window
8120 System which meet the criteria listed below should declare
8121 in their control data that they provide the virtual
8122 package <tt>x-terminal-emulator</tt>. They should also
8123 register themselves as an alternative for
8124 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8129 To be an <tt>x-terminal-emulator</tt>, a program must:
8130 <list compact="compact">
8132 Be able to emulate a DEC VT100 terminal, or a
8133 compatible terminal.
8137 Support the command-line option <tt>-e
8138 <var>command</var></tt>, which creates a new
8139 terminal window<footnote>
8140 "New terminal window" does not necessarily mean
8141 a new top-level X window directly parented by
8142 the window manager; it could, if the terminal
8143 emulator application were so coded, be a new
8144 "view" in a multiple-document interface (MDI).
8146 and runs the specified <var>command</var>,
8147 interpreting the entirety of the rest of the command
8148 line as a command to pass straight to exec, in the
8149 manner that <tt>xterm</tt> does.
8153 Support the command-line option <tt>-T
8154 <var>title</var></tt>, which creates a new terminal
8155 window with the window title <var>title</var>.
8162 <heading>Packages providing a window manager</heading>
8165 Packages that provide a window manager should declare in
8166 their control data that they provide the virtual package
8167 <tt>x-window-manager</tt>. They should also register
8168 themselves as an alternative for
8169 <file>/usr/bin/x-window-manager</file>, with a priority
8170 calculated as follows:
8171 <list compact="compact">
8173 Start with a priority of 20.
8177 If the window manager supports the Debian menu
8178 system, add 20 points if this support is available
8179 in the package's default configuration (i.e., no
8180 configuration files belonging to the system or user
8181 have to be edited to activate the feature); if
8182 configuration files must be modified, add only 10
8188 If the window manager complies with <url
8189 id="http://www.freedesktop.org/Standards/wm-spec"
8190 name="The Window Manager Specification Project">,
8191 written by the <url id="http://www.freedesktop.org/"
8192 name="Free Desktop Group">, add 40 points.
8196 If the window manager permits the X session to be
8197 restarted using a <em>different</em> window manager
8198 (without killing the X server) in its default
8199 configuration, add 10 points; otherwise add none.
8206 <heading>Packages providing fonts</heading>
8209 Packages that provide fonts for the X Window
8211 For the purposes of Debian Policy, a "font for the X
8212 Window System" is one which is accessed via X protocol
8213 requests. Fonts for the Linux console, for PostScript
8214 renderer, or any other purpose, do not fit this
8215 definition. Any tool which makes such fonts available
8216 to the X Window System, however, must abide by this
8219 must do a number of things to ensure that they are both
8220 available without modification of the X or font server
8221 configuration, and that they do not corrupt files used by
8222 other font packages to register information about
8226 Fonts of any type supported by the X Window System
8227 must be in a separate binary package from any
8228 executables, libraries, or documentation (except
8229 that specific to the fonts shipped, such as their
8230 license information). If one or more of the fonts
8231 so packaged are necessary for proper operation of
8232 the package with which they are associated the font
8233 package may be Recommended; if the fonts merely
8234 provide an enhancement, a Suggests relationship may
8235 be used. Packages must not Depend on font
8237 This is because the X server may retrieve fonts
8238 from the local file system or over the network
8239 from an X font server; the Debian package system
8240 is empowered to deal only with the local
8246 BDF fonts must be converted to PCF fonts with the
8247 <prgn>bdftopcf</prgn> utility (available in the
8248 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8249 placed in a directory that corresponds to their
8251 <list compact="compact">
8253 100 dpi fonts must be placed in
8254 <file>/usr/share/fonts/X11/100dpi/</file>.
8258 75 dpi fonts must be placed in
8259 <file>/usr/share/fonts/X11/75dpi/</file>.
8263 Character-cell fonts, cursor fonts, and other
8264 low-resolution fonts must be placed in
8265 <file>/usr/share/fonts/X11/misc/</file>.
8271 Speedo fonts must be placed in
8272 <file>/usr/share/fonts/X11/Speedo/</file>.
8276 Type 1 fonts must be placed in
8277 <file>/usr/share/fonts/X11/Type1/</file>. If font
8278 metric files are available, they must be placed here
8283 Subdirectories of <file>/usr/share/fonts/X11/</file>
8284 other than those listed above must be neither
8285 created nor used. (The <file>PEX</file>, <file>CID</file>,
8286 and <file>cyrillic</file> directories are excepted for
8287 historical reasons, but installation of files into
8288 these directories remains discouraged.)
8292 Font packages may, instead of placing files directly
8293 in the X font directories listed above, provide
8294 symbolic links in that font directory pointing to
8295 the files' actual location in the filesystem. Such
8296 a location must comply with the FHS.
8300 Font packages should not contain both 75dpi and
8301 100dpi versions of a font. If both are available,
8302 they should be provided in separate binary packages
8303 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8304 the names of the packages containing the
8305 corresponding fonts.
8309 Fonts destined for the <file>misc</file> subdirectory
8310 should not be included in the same package as 75dpi
8311 or 100dpi fonts; instead, they should be provided in
8312 a separate package with <tt>-misc</tt> appended to
8317 Font packages must not provide the files
8318 <file>fonts.dir</file>, <file>fonts.alias</file>, or
8319 <file>fonts.scale</file> in a font directory:
8322 <file>fonts.dir</file> files must not be provided at all.
8326 <file>fonts.alias</file> and <file>fonts.scale</file>
8327 files, if needed, should be provided in the
8329 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
8330 where <var>fontdir</var> is the name of the
8332 <file>/usr/share/fonts/X11/</file> where the
8333 package's corresponding fonts are stored
8334 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
8335 <var>package</var> is the name of the package
8336 that provides these fonts, and
8337 <var>extension</var> is either <tt>scale</tt>
8338 or <tt>alias</tt>, whichever corresponds to
8345 Font packages must declare a dependency on
8346 <tt>xfonts-utils</tt> in their control
8351 Font packages that provide one or more
8352 <file>fonts.scale</file> files as described above must
8353 invoke <prgn>update-fonts-scale</prgn> on each
8354 directory into which they installed fonts
8355 <em>before</em> invoking
8356 <prgn>update-fonts-dir</prgn> on that directory.
8357 This invocation must occur in both the
8358 <prgn>postinst</prgn> (for all arguments) and
8359 <prgn>postrm</prgn> (for all arguments except
8360 <tt>upgrade</tt>) scripts.
8364 Font packages that provide one or more
8365 <file>fonts.alias</file> files as described above must
8366 invoke <prgn>update-fonts-alias</prgn> on each
8367 directory into which they installed fonts. This
8368 invocation must occur in both the
8369 <prgn>postinst</prgn> (for all arguments) and
8370 <prgn>postrm</prgn> (for all arguments except
8371 <tt>upgrade</tt>) scripts.
8375 Font packages must invoke
8376 <prgn>update-fonts-dir</prgn> on each directory into
8377 which they installed fonts. This invocation must
8378 occur in both the <prgn>postinst</prgn> (for all
8379 arguments) and <prgn>postrm</prgn> (for all
8380 arguments except <tt>upgrade</tt>) scripts.
8384 Font packages must not provide alias names for the
8385 fonts they include which collide with alias names
8386 already in use by fonts already packaged.
8390 Font packages must not provide fonts with the same
8391 XLFD registry name as another font already packaged.
8398 <heading>Application defaults files</heading>
8401 Application defaults files must be installed in the
8402 directory <file>/etc/X11/app-defaults/</file> (use of a
8403 localized subdirectory of <file>/etc/X11/</file> as described
8404 in the <em>X Toolkit Intrinsics - C Language
8405 Interface</em> manual is also permitted). They must be
8406 registered as <tt>conffile</tt>s or handled as
8407 configuration files. Packages must not provide the
8408 directory <file>/usr/X11R6/lib/X11/app-defaults/</file>.
8412 Customization of programs' X resources may also be
8413 supported with the provision of a file with the same name
8414 as that of the package placed in the
8415 <file>/etc/X11/Xresources/</file> directory, which must
8416 registered as a <tt>conffile</tt> or handled as a
8417 configuration file.<footnote>
8418 Note that this mechanism is not the same as using
8419 app-defaults; app-defaults are tied to the client
8420 binary on the local file system, whereas X resources
8421 are stored in the X server and affect all connecting
8424 <em>Important:</em> packages that install files into the
8425 <file>/etc/X11/Xresources/</file> directory must conflict with
8426 <tt>xbase (<< 3.3.2.3a-2)</tt>; if this is not done
8427 it is possible for the installing package to destroy a
8428 previously-existing <file>/etc/X11/Xresources</file> file
8429 which had been customized by the system administrator.
8434 <heading>Installation directory issues</heading>
8437 Packages using the X Window System should not be
8438 configured to install files under the
8439 <file>/usr/X11R6/</file> directory. The
8440 <file>/usr/X11R6/</file> directory hierarchy should be
8441 regarded as obsolete.
8445 Programs that use GNU <prgn>autoconf</prgn> and
8446 <prgn>automake</prgn> are usually easily configured at
8447 compile time to use <file>/usr/</file> instead of
8448 <file>/usr/X11R6/</file>, and this should be done whenever
8449 possible. Configuration files for window managers and
8450 display managers should be placed in a subdirectory of
8451 <file>/etc/X11/</file> corresponding to the package name due
8452 to these programs' tight integration with the mechanisms
8453 of the X Window System. Application-level programs should
8454 use the <file>/etc/</file> directory unless otherwise mandated
8459 The installation of files into subdirectories
8460 of <file>/usr/X11R6/include/X11/</file> and
8461 <file>/usr/X11R6/lib/X11/</file> is now prohibited;
8462 package maintainers should determine if subdirectories of
8463 <file>/usr/lib/</file> and <file>/usr/share/</file> can be used
8468 Packages should install any relevant files into the
8469 directories <file>/usr/include/X11/</file> and
8470 <file>/usr/lib/X11/</file>, but if they do so, they must
8471 pre-depend on <tt>x11-common (>=
8472 1:7.0.0)</tt><footnote>
8474 These libraries used to be all symbolic
8475 links. However, with <tt>X11R7</tt>,
8476 <tt>/usr/include/X11</tt> and <tt>/usr/lib/X11</tt>
8477 are now real directories, and packages
8478 <strong>should</strong> ship their files here instead
8479 of in <tt>/usr/X11R6/{include,lib}/X11</tt>.
8480 <tt>x11-common (>= 1:7.0.0) </tt> is the package
8481 responsible for converting these symlinks into
8489 <heading>The OSF/Motif and OpenMotif libraries</heading>
8492 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8493 OpenMotif libraries</em><footnote>
8494 OSF/Motif and OpenMotif are collectively referred to as
8495 "Motif" in this policy document.
8497 should be compiled against and tested with LessTif (a free
8498 re-implementation of Motif) instead. If the maintainer
8499 judges that the program or programs do not work
8500 sufficiently well with LessTif to be distributed and
8501 supported, but do so when compiled against Motif, then two
8502 versions of the package should be created; one linked
8503 statically against Motif and with <tt>-smotif</tt>
8504 appended to the package name, and one linked dynamically
8505 against Motif and with <tt>-dmotif</tt> appended to the
8510 Both Motif-linked versions are dependent
8511 upon non-DFSG-compliant software and thus cannot be
8512 uploaded to the <em>main</em> distribution; if the
8513 software is itself DFSG-compliant it may be uploaded to
8514 the <em>contrib</em> distribution. While known existing
8515 versions of Motif permit unlimited redistribution of
8516 binaries linked against the library (whether statically or
8517 dynamically), it is the package maintainer's
8518 responsibility to determine whether this is permitted by
8519 the license of the copy of Motif in their possession.
8525 <heading>Perl programs and modules</heading>
8528 Perl programs and modules should follow the current Perl policy.
8532 The Perl policy can be found in the <tt>perl-policy</tt>
8533 files in the <tt>debian-policy</tt> package.
8534 It is also available from the Debian web mirrors at
8535 <tt><url name="/doc/packaging-manuals/perl-policy/"
8536 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8541 <heading>Emacs lisp programs</heading>
8544 Please refer to the "Debian Emacs Policy" for details of how to
8545 package emacs lisp programs.
8549 The Emacs policy is available in
8550 <file>debian-emacs-policy.gz</file> of the
8551 <package>emacsen-common</package> package.
8552 It is also available from the Debian web mirrors at
8553 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8554 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8559 <heading>Games</heading>
8562 The permissions on <file>/var/games</file> are mode 755, owner
8563 <tt>root</tt> and group <tt>root</tt>.
8567 Each game decides on its own security policy.</p>
8570 Games which require protected, privileged access to
8571 high-score files, saved games, etc., may be made
8572 set-<em>group</em>-id (mode 2755) and owned by
8573 <tt>root.games</tt>, and use files and directories with
8574 appropriate permissions (770 <tt>root.games</tt>, for
8575 example). They must not be made
8576 set-<em>user</em>-id, as this causes security problems. (If
8577 an attacker can subvert any set-user-id game they can
8578 overwrite the executable of any other, causing other players
8579 of these games to run a Trojan horse program. With a
8580 set-group-id game the attacker only gets access to less
8581 important game data, and if they can get at the other
8582 players' accounts at all it will take considerably more
8586 Some packages, for example some fortune cookie programs, are
8587 configured by the upstream authors to install with their
8588 data files or other static information made unreadable so
8589 that they can only be accessed through set-id programs
8590 provided. You should not do this in a Debian package: anyone can
8591 download the <file>.deb</file> file and read the data from it,
8592 so there is no point making the files unreadable. Not
8593 making the files unreadable also means that you don't have
8594 to make so many programs set-id, which reduces the risk of a
8598 As described in the FHS, binaries of games should be
8599 installed in the directory <file>/usr/games</file>. This also
8600 applies to games that use the X Window System. Manual pages
8601 for games (X and non-X games) should be installed in
8602 <file>/usr/share/man/man6</file>.</p>
8608 <heading>Documentation</heading>
8611 <heading>Manual pages</heading>
8614 You should install manual pages in <prgn>nroff</prgn> source
8615 form, in appropriate places under <file>/usr/share/man</file>.
8616 You should only use sections 1 to 9 (see the FHS for more
8617 details). You must not install a pre-formatted "cat page".
8621 Each program, utility, and function should have an
8622 associated manual page included in the same package. It is
8623 suggested that all configuration files also have a manual
8624 page included as well. Manual pages for protocols and other
8625 auxiliary things are optional.
8629 If no manual page is available, this is considered as a bug
8630 and should be reported to the Debian Bug Tracking System (the
8631 maintainer of the package is allowed to write this bug report
8632 themselves, if they so desire). Do not close the bug report
8633 until a proper man page is available.<footnote>
8634 It is not very hard to write a man page. See the
8635 <url id="http://www.schweikhardt.net/man_page_howto.html"
8636 name="Man-Page-HOWTO">,
8637 <manref name="man" section="7">, the examples
8638 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8639 the helper programs <prgn>help2man</prgn>, or the
8640 directory <file>/usr/share/doc/man-db/examples</file>.
8645 You may forward a complaint about a missing man page to the
8646 upstream authors, and mark the bug as forwarded in the
8647 Debian bug tracking system. Even though the GNU Project do
8648 not in general consider the lack of a man page to be a bug,
8649 we do; if they tell you that they don't consider it a bug
8650 you should leave the bug in our bug tracking system open
8655 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8659 If one man page needs to be accessible via several names it
8660 is better to use a symbolic link than the <file>.so</file>
8661 feature, but there is no need to fiddle with the relevant
8662 parts of the upstream source to change from <file>.so</file> to
8663 symlinks: don't do it unless it's easy. You should not
8664 create hard links in the manual page directories, nor put
8665 absolute filenames in <file>.so</file> directives. The filename
8666 in a <file>.so</file> in a man page should be relative to the
8667 base of the man page tree (usually
8668 <file>/usr/share/man</file>). If you do not create any links
8669 (whether symlinks, hard links, or <tt>.so</tt> directives)
8670 in the file system to the alternate names of the man page,
8671 then you should not rely on <prgn>man</prgn> finding your
8672 man page under those names based solely on the information in
8673 the man page's header.<footnote>
8674 Supporting this in <prgn>man</prgn> often requires
8675 unreasonable processing time to find a manual page or to
8676 report that none exists, and moves knowledge into man's
8677 database that would be better left in the file system.
8678 This support is therefore deprecated and will cease to
8679 be present in the future.
8684 Manual pages in locale-specific subdirectories of
8685 <file>/usr/share/man</file> should use either UTF-8 or the usual
8686 legacy encoding for that language (normally the one corresponding
8687 to the shortest relevant locale name in
8688 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
8689 <file>/usr/share/man/fr</file> should use either UTF-8 or
8690 ISO-8859-1.<footnote>
8691 <prgn>man</prgn> will automatically detect whether UTF-8 is in
8692 use. In future, all manual pages will be required to use
8698 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
8699 included in the subdirectory name unless it indicates a
8700 significant difference in the language, as this excludes
8701 speakers of the language in other countries.<footnote>
8702 At the time of writing, Chinese and Portuguese are the main
8703 languages with such differences, so <file>pt_BR</file>,
8704 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
8709 Due to limitations in current implementations, all characters
8710 in the manual page source should be representable in the usual
8711 legacy encoding for that language, even if the file is
8712 actually encoded in UTF-8. Safe alternative ways to write many
8713 characters outside that range may be found in
8714 <manref name="groff_char" section="7">.
8719 <heading>Info documents</heading>
8722 Info documents should be installed in <file>/usr/share/info</file>.
8723 They should be compressed with <tt>gzip -9</tt>.
8727 Your package should call <prgn>install-info</prgn> to update
8728 the Info <file>dir</file> file in its <prgn>postinst</prgn>
8729 script when called with a <tt>configure</tt> argument, for
8731 <example compact="compact">
8732 install-info --quiet --section Development Development \
8733 /usr/share/info/foobar.info
8737 It is a good idea to specify a section for the location of
8738 your program; this is done with the <tt>--section</tt>
8739 switch. To determine which section to use, you should look
8740 at <file>/usr/share/info/dir</file> on your system and choose the most
8741 relevant (or create a new section if none of the current
8742 sections are relevant). Note that the <tt>--section</tt>
8743 flag takes two arguments; the first is a regular expression
8744 to match (case-insensitively) against an existing section,
8745 the second is used when creating a new one.</p>
8748 You should remove the entries in the <prgn>prerm</prgn>
8749 script when called with a <tt>remove</tt> argument:
8750 <example compact="compact">
8751 install-info --quiet --remove /usr/share/info/foobar.info
8755 If <prgn>install-info</prgn> cannot find a description entry
8756 in the Info file you must supply one. See <manref
8757 name="install-info" section="8"> for details.</p>
8761 <heading>Additional documentation</heading>
8764 Any additional documentation that comes with the package may
8765 be installed at the discretion of the package maintainer.
8766 Plain text documentation should be installed in the directory
8767 <file>/usr/share/doc/<var>package</var></file>, where
8768 <var>package</var> is the name of the package, and
8769 compressed with <tt>gzip -9</tt> unless it is small.
8773 If a package comes with large amounts of documentation which
8774 many users of the package will not require you should create
8775 a separate binary package to contain it, so that it does not
8776 take up disk space on the machines of users who do not need
8777 or want it installed.</p>
8780 It is often a good idea to put text information files
8781 (<file>README</file>s, changelogs, and so forth) that come with
8782 the source package in <file>/usr/share/doc/<var>package</var></file>
8783 in the binary package. However, you don't need to install
8784 the instructions for building and installing the package, of
8788 Packages must not require the existence of any files in
8789 <file>/usr/share/doc/</file> in order to function
8791 The system administrator should be able to
8792 delete files in <file>/usr/share/doc/</file> without causing
8793 any programs to break.
8795 Any files that are referenced by programs but are also
8796 useful as stand alone documentation should be installed under
8797 <file>/usr/share/<var>package</var>/</file> with symbolic links from
8798 <file>/usr/share/doc/<var>package</var></file>.
8802 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8803 link to another directory in <file>/usr/share/doc</file> only if
8804 the two packages both come from the same source and the
8805 first package Depends on the second.<footnote>
8807 Please note that this does not override the section on
8808 changelog files below, so the file
8809 <file>/usr/share/<var>package</var>/changelog.Debian.gz</file>
8810 must refer to the changelog for the current version of
8811 <var>package</var> in question. In practice, this means
8812 that the sources of the target and the destination of the
8813 symlink must be the same (same source package and
8820 Former Debian releases placed all additional documentation
8821 in <file>/usr/doc/<var>package</var></file>. This has been
8822 changed to <file>/usr/share/doc/<var>package</var></file>,
8823 and packages must not put documentation in the directory
8824 <file>/usr/doc/<var>package</var></file>. <footnote>
8825 At this phase of the transition, we no longer require a
8826 symbolic link in <file>/usr/doc/</file>. At a later point,
8827 policy shall change to make the symbolic links a bug.
8833 <heading>Preferred documentation formats</heading>
8836 The unification of Debian documentation is being carried out
8840 If your package comes with extensive documentation in a
8841 markup format that can be converted to various other formats
8842 you should if possible ship HTML versions in a binary
8843 package, in the directory
8844 <file>/usr/share/doc/<var>appropriate-package</var></file> or
8845 its subdirectories.<footnote>
8846 The rationale: The important thing here is that HTML
8847 docs should be available in <em>some</em> package, not
8848 necessarily in the main binary package.
8853 Other formats such as PostScript may be provided at the
8854 package maintainer's discretion.
8858 <sect id="copyrightfile">
8859 <heading>Copyright information</heading>
8862 Every package must be accompanied by a verbatim copy of its
8863 copyright and distribution license in the file
8864 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
8865 file must neither be compressed nor be a symbolic link.
8869 In addition, the copyright file must say where the upstream
8870 sources (if any) were obtained. It should name the original
8871 authors of the package and the Debian maintainer(s) who were
8872 involved with its creation.
8876 Packages in the <em>contrib</em> or <em>non-free</em> categories
8877 should state in the copyright file that the package is not part
8878 of the Debian GNU/Linux distribution and briefly explain why.
8882 A copy of the file which will be installed in
8883 <file>/usr/share/doc/<var>package</var>/copyright</file> should
8884 be in <file>debian/copyright</file> in the source package.
8888 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8889 link to another directory in <file>/usr/share/doc</file> only if
8890 the two packages both come from the same source and the
8891 first package Depends on the second. These rules are
8892 important because copyrights must be extractable by
8897 Packages distributed under the UCB BSD license, the Apache
8898 license (version 2.0), the Artistic license, the GNU GPL
8899 (version 2 or 3), the GNU LGPL (versions 2, 2.1, or 3), and
8900 the GNU FDL (version 1.2) should refer to the corresponding
8901 files under <file>/usr/share/common-licenses</file>,<footnote>
8904 <file>/usr/share/common-licenses/BSD</file>,
8905 <file>/usr/share/common-licenses/Apache-2.0</file>,
8906 <file>/usr/share/common-licenses/Artistic</file>,
8907 <file>/usr/share/common-licenses/GPL-2</file>,
8908 <file>/usr/share/common-licenses/GPL-3</file>,
8909 <file>/usr/share/common-licenses/LGPL-2</file>,
8910 <file>/usr/share/common-licenses/LGPL-2.1</file>,
8911 <file>/usr/share/common-licenses/LGPL-3</file>, and
8912 <file>/usr/share/common-licenses/GFDL-1.2</file>
8915 </footnote> rather than quoting them in the copyright
8920 You should not use the copyright file as a general <file>README</file>
8921 file. If your package has such a file it should be
8922 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
8923 <file>README.Debian</file> or some other appropriate place.</p>
8927 <heading>Examples</heading>
8930 Any examples (configurations, source files, whatever),
8931 should be installed in a directory
8932 <file>/usr/share/doc/<var>package</var>/examples</file>. These
8933 files should not be referenced by any program: they're there
8934 for the benefit of the system administrator and users as
8935 documentation only. Architecture-specific example files
8936 should be installed in a directory
8937 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
8939 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
8940 latter directory itself may be a symbolic link to the
8945 If the purpose of a package is to provide examples, then the
8946 example files may be installed into
8947 <file>/usr/share/doc/<var>package</var></file>.
8951 <sect id="changelogs">
8952 <heading>Changelog files</heading>
8955 Packages that are not Debian-native must contain a
8956 compressed copy of the <file>debian/changelog</file> file from
8957 the Debian source tree in
8958 <file>/usr/share/doc/<var>package</var></file> with the name
8959 <file>changelog.Debian.gz</file>.
8963 If an upstream changelog is available, it should be accessible as
8964 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
8965 plain text. If the upstream changelog is distributed in
8966 HTML, it should be made available in that form as
8967 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
8968 and a plain text <file>changelog.gz</file> should be generated
8969 from it using, for example, <tt>lynx -dump -nolist</tt>. If
8970 the upstream changelog files do not already conform to this
8971 naming convention, then this may be achieved either by
8972 renaming the files, or by adding a symbolic link, at the
8973 maintainer's discretion.<footnote>
8974 Rationale: People should not have to look in places for
8975 upstream changelogs merely because they are given
8976 different names or are distributed in HTML format.
8981 All of these files should be installed compressed using
8982 <tt>gzip -9</tt>, as they will become large with time even
8983 if they start out small.
8987 If the package has only one changelog which is used both as
8988 the Debian changelog and the upstream one because there is
8989 no separate upstream maintainer then that changelog should
8990 usually be installed as
8991 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
8992 there is a separate upstream maintainer, but no upstream
8993 changelog, then the Debian changelog should still be called
8994 <file>changelog.Debian.gz</file>.
8998 For details about the format and contents of the Debian
8999 changelog file, please see <ref id="dpkgchangelog">.
9004 <appendix id="pkg-scope">
9005 <heading>Introduction and scope of these appendices</heading>
9008 These appendices are taken essentially verbatim from the
9009 now-deprecated Packaging Manual, version 3.2.1.0. They are
9010 the chapters which are likely to be of use to package
9011 maintainers and which have not already been included in the
9012 policy document itself. Most of these sections are very likely
9013 not relevant to policy; they should be treated as
9014 documentation for the packaging system. Please note that these
9015 appendices are included for convenience, and for historical
9016 reasons: they used to be part of policy package, and they have
9017 not yet been incorporated into dpkg documentation. However,
9018 they still have value, and hence they are presented here.
9022 They have not yet been checked to ensure that they are
9023 compatible with the contents of policy, and if there are any
9024 contradictions, the version in the main policy document takes
9025 precedence. The remaining chapters of the old Packaging
9026 Manual have also not been read in detail to ensure that there
9027 are not parts which have been left out. Both of these will be
9032 Certain parts of the Packaging manual were integrated into the
9033 Policy Manual proper, and removed from the appendices. Links
9034 have been placed from the old locations to the new ones.
9038 <prgn>dpkg</prgn> is a suite of programs for creating binary
9039 package files and installing and removing them on Unix
9041 <prgn>dpkg</prgn> is targeted primarily at Debian
9042 GNU/Linux, but may work on or be ported to other
9048 The binary packages are designed for the management of
9049 installed executable programs (usually compiled binaries) and
9050 their associated data, though source code examples and
9051 documentation are provided as part of some packages.</p>
9054 This manual describes the technical aspects of creating Debian
9055 binary packages (<file>.deb</file> files). It documents the
9056 behavior of the package management programs
9057 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9058 they interact with packages.</p>
9061 It also documents the interaction between
9062 <prgn>dselect</prgn>'s core and the access method scripts it
9063 uses to actually install the selected packages, and describes
9064 how to create a new access method.</p>
9067 This manual does not go into detail about the options and
9068 usage of the package building and installation tools. It
9069 should therefore be read in conjunction with those programs'
9074 The utility programs which are provided with <prgn>dpkg</prgn>
9075 for managing various system configuration and similar issues,
9076 such as <prgn>update-rc.d</prgn> and
9077 <prgn>install-info</prgn>, are not described in detail here -
9078 please see their man pages.
9082 It is assumed that the reader is reasonably familiar with the
9083 <prgn>dpkg</prgn> System Administrators' manual.
9084 Unfortunately this manual does not yet exist.
9088 The Debian version of the FSF's GNU hello program is provided
9089 as an example for people wishing to create Debian
9090 packages. The Debian <prgn>debmake</prgn> package is
9091 recommended as a very helpful tool in creating and maintaining
9092 Debian packages. However, while the tools and examples are
9093 helpful, they do not replace the need to read and follow the
9094 Policy and Programmer's Manual.</p>
9097 <appendix id="pkg-binarypkg">
9098 <heading>Binary packages (from old Packaging Manual)</heading>
9101 The binary package has two main sections. The first part
9102 consists of various control information files and scripts used
9103 by <prgn>dpkg</prgn> when installing and removing. See <ref
9104 id="pkg-controlarea">.
9108 The second part is an archive containing the files and
9109 directories to be installed.
9113 In the future binary packages may also contain other
9114 components, such as checksums and digital signatures. The
9115 format for the archive is described in full in the
9116 <file>deb(5)</file> man page.
9120 <sect id="pkg-bincreating"><heading>Creating package files -
9121 <prgn>dpkg-deb</prgn>
9125 All manipulation of binary package files is done by
9126 <prgn>dpkg-deb</prgn>; it's the only program that has
9127 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9128 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9129 will spot that the options requested are appropriate to
9130 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9135 In order to create a binary package you must make a
9136 directory tree which contains all the files and directories
9137 you want to have in the file system data part of the package.
9138 In Debian-format source packages this directory is usually
9139 <file>debian/tmp</file>, relative to the top of the package's
9144 They should have the locations (relative to the root of the
9145 directory tree you're constructing) ownerships and
9146 permissions which you want them to have on the system when
9151 With current versions of <prgn>dpkg</prgn> the uid/username
9152 and gid/groupname mappings for the users and groups being
9153 used should be the same on the system where the package is
9154 built and the one where it is installed.
9158 You need to add one special directory to the root of the
9159 miniature file system tree you're creating:
9160 <prgn>DEBIAN</prgn>. It should contain the control
9161 information files, notably the binary package control file
9162 (see <ref id="pkg-controlfile">).
9166 The <prgn>DEBIAN</prgn> directory will not appear in the
9167 file system archive of the package, and so won't be installed
9168 by <prgn>dpkg</prgn> when the package is installed.
9172 When you've prepared the package, you should invoke:
9174 dpkg --build <var>directory</var>
9179 This will build the package in
9180 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9181 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9182 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9187 See the man page <manref name="dpkg-deb" section="8"> for details of how
9188 to examine the contents of this newly-created file. You may find the
9189 output of following commands enlightening:
9191 dpkg-deb --info <var>filename</var>.deb
9192 dpkg-deb --contents <var>filename</var>.deb
9193 dpkg --contents <var>filename</var>.deb
9195 To view the copyright file for a package you could use this command:
9197 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - \*/copyright | pager
9202 <sect id="pkg-controlarea">
9203 <heading>Package control information files</heading>
9206 The control information portion of a binary package is a
9207 collection of files with names known to <prgn>dpkg</prgn>.
9208 It will treat the contents of these files specially - some
9209 of them contain information used by <prgn>dpkg</prgn> when
9210 installing or removing the package; others are scripts which
9211 the package maintainer wants <prgn>dpkg</prgn> to run.
9215 It is possible to put other files in the package control
9216 area, but this is not generally a good idea (though they
9217 will largely be ignored).
9221 Here is a brief list of the control info files supported by
9222 <prgn>dpkg</prgn> and a summary of what they're used for.
9227 <tag><tt>control</tt>
9230 This is the key description file used by
9231 <prgn>dpkg</prgn>. It specifies the package's name
9232 and version, gives its description for the user,
9233 states its relationships with other packages, and so
9234 forth. See <ref id="sourcecontrolfiles"> and
9235 <ref id="binarycontrolfiles">.
9239 It is usually generated automatically from information
9240 in the source package by the
9241 <prgn>dpkg-gencontrol</prgn> program, and with
9242 assistance from <prgn>dpkg-shlibdeps</prgn>.
9243 See <ref id="pkg-sourcetools">.
9247 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9252 These are executable files (usually scripts) which
9253 <prgn>dpkg</prgn> runs during installation, upgrade
9254 and removal of packages. They allow the package to
9255 deal with matters which are particular to that package
9256 or require more complicated processing than that
9257 provided by <prgn>dpkg</prgn>. Details of when and
9258 how they are called are in <ref id="maintainerscripts">.
9262 It is very important to make these scripts idempotent.
9263 See <ref id="idempotency">.
9267 The maintainer scripts are guaranteed to run with a
9268 controlling terminal and can interact with the user.
9269 See <ref id="controllingterminal">.
9273 <tag><tt>conffiles</tt>
9276 This file contains a list of configuration files which
9277 are to be handled automatically by <prgn>dpkg</prgn>
9278 (see <ref id="pkg-conffiles">). Note that not necessarily
9279 every configuration file should be listed here.
9282 <tag><tt>shlibs</tt>
9285 This file contains a list of the shared libraries
9286 supplied by the package, with dependency details for
9287 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9288 when it determines what dependencies are required in a
9289 package control file. The <tt>shlibs</tt> file format
9290 is described on <ref id="shlibs">.
9295 <sect id="pkg-controlfile">
9296 <heading>The main control information file: <tt>control</tt></heading>
9299 The most important control information file used by
9300 <prgn>dpkg</prgn> when it installs a package is
9301 <tt>control</tt>. It contains all the package's "vital
9306 The binary package control files of packages built from
9307 Debian sources are made by a special tool,
9308 <prgn>dpkg-gencontrol</prgn>, which reads
9309 <file>debian/control</file> and <file>debian/changelog</file> to
9310 find the information it needs. See <ref id="pkg-sourcepkg"> for
9315 The fields in binary package control files are listed in
9316 <ref id="binarycontrolfiles">.
9320 A description of the syntax of control files and the purpose
9321 of the fields is available in <ref id="controlfields">.
9326 <heading>Time Stamps</heading>
9329 See <ref id="timestamps">.
9334 <appendix id="pkg-sourcepkg">
9335 <heading>Source packages (from old Packaging Manual) </heading>
9338 The Debian binary packages in the distribution are generated
9339 from Debian sources, which are in a special format to assist
9340 the easy and automatic building of binaries.
9343 <sect id="pkg-sourcetools">
9344 <heading>Tools for processing source packages</heading>
9347 Various tools are provided for manipulating source packages;
9348 they pack and unpack sources and help build of binary
9349 packages and help manage the distribution of new versions.
9353 They are introduced and typical uses described here; see
9354 <manref name="dpkg-source" section="1"> for full
9355 documentation about their arguments and operation.
9359 For examples of how to construct a Debian source package,
9360 and how to use those utilities that are used by Debian
9361 source packages, please see the <prgn>hello</prgn> example
9365 <sect1 id="pkg-dpkg-source">
9367 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
9372 This program is frequently used by hand, and is also
9373 called from package-independent automated building scripts
9374 such as <prgn>dpkg-buildpackage</prgn>.
9378 To unpack a package it is typically invoked with
9380 dpkg-source -x <var>.../path/to/filename</var>.dsc
9385 with the <file><var>filename</var>.tar.gz</file> and
9386 <file><var>filename</var>.diff.gz</file> (if applicable) in
9387 the same directory. It unpacks into
9388 <file><var>package</var>-<var>version</var></file>, and if
9390 <file><var>package</var>-<var>version</var>.orig</file>, in
9391 the current directory.
9395 To create a packed source archive it is typically invoked:
9397 dpkg-source -b <var>package</var>-<var>version</var>
9402 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
9403 <file>.diff.gz</file> (if appropriate) in the current
9404 directory. <prgn>dpkg-source</prgn> does not clean the
9405 source tree first - this must be done separately if it is
9410 See also <ref id="pkg-sourcearchives">.</p>
9414 <sect1 id="pkg-dpkg-buildpackage">
9416 <prgn>dpkg-buildpackage</prgn> - overall package-building
9421 <prgn>dpkg-buildpackage</prgn> is a script which invokes
9422 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
9423 targets <tt>clean</tt>, <tt>build</tt> and
9424 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
9425 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
9426 source and binary package upload.
9430 It is usually invoked by hand from the top level of the
9431 built or unbuilt source directory. It may be invoked with
9432 no arguments; useful arguments include:
9433 <taglist compact="compact">
9434 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
9437 Do not sign the <tt>.changes</tt> file or the
9438 source package <tt>.dsc</tt> file, respectively.</p>
9440 <tag><tt>-p<var>sign-command</var></tt></tag>
9443 Invoke <var>sign-command</var> instead of finding
9444 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
9445 <var>sign-command</var> must behave just like
9446 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9448 <tag><tt>-r<var>root-command</var></tt></tag>
9451 When root privilege is required, invoke the command
9452 <var>root-command</var>. <var>root-command</var>
9453 should invoke its first argument as a command, from
9454 the <prgn>PATH</prgn> if necessary, and pass its
9455 second and subsequent arguments to the command it
9456 calls. If no <var>root-command</var> is supplied
9457 then <var>dpkg-buildpackage</var> will take no
9458 special action to gain root privilege, so that for
9459 most packages it will have to be invoked as root to
9462 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9465 Two types of binary-only build and upload - see
9466 <manref name="dpkg-source" section="1">.
9473 <sect1 id="pkg-dpkg-gencontrol">
9475 <prgn>dpkg-gencontrol</prgn> - generates binary package
9480 This program is usually called from <file>debian/rules</file>
9481 (see <ref id="pkg-sourcetree">) in the top level of the source
9486 This is usually done just before the files and directories in the
9487 temporary directory tree where the package is being built have their
9488 permissions and ownerships set and the package is constructed using
9489 <prgn>dpkg-deb/</prgn>
9491 This is so that the control file which is produced has
9492 the right permissions
9497 <prgn>dpkg-gencontrol</prgn> must be called after all the
9498 files which are to go into the package have been placed in
9499 the temporary build directory, so that its calculation of
9500 the installed size of a package is correct.
9504 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9505 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9506 variable substitutions created by
9507 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9512 For a package which generates only one binary package, and
9513 which builds it in <file>debian/tmp</file> relative to the top
9514 of the source package, it is usually sufficient to call
9515 <prgn>dpkg-gencontrol</prgn>.
9519 Sources which build several binaries will typically need
9522 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9523 </example> The <tt>-P</tt> tells
9524 <prgn>dpkg-gencontrol</prgn> that the package is being
9525 built in a non-default directory, and the <tt>-p</tt>
9526 tells it which package's control file should be generated.
9530 <prgn>dpkg-gencontrol</prgn> also adds information to the
9531 list of files in <file>debian/files</file>, for the benefit of
9532 (for example) a future invocation of
9533 <prgn>dpkg-genchanges</prgn>.</p>
9536 <sect1 id="pkg-dpkg-shlibdeps">
9538 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9543 This program is usually called from <file>debian/rules</file>
9544 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9545 id="pkg-sourcetree">), in the top level of the source tree.
9549 Its arguments are executables.
9552 In a forthcoming dpkg version,
9553 <prgn>dpkg-shlibdeps</prgn> would be required to be
9554 called on shared libraries as well.
9557 They may be specified either in the locations in the
9558 source tree where they are created or in the locations
9559 in the temporary build tree where they are installed
9560 prior to binary package creation.
9562 </footnote> for which shared library dependencies should
9563 be included in the binary package's control file.
9567 If some of the found shared libraries should only
9568 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9569 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9570 by using the <tt>-d<var>dependency-field</var></tt> option
9571 before those executable(s). (Each <tt>-d</tt> option
9572 takes effect until the next <tt>-d</tt>.)
9576 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9577 output control file to be modified. Instead by default it
9578 adds to the <file>debian/substvars</file> file variable
9579 settings like <tt>shlibs:Depends</tt>. These variable
9580 settings must be referenced in dependency fields in the
9581 appropriate per-binary-package sections of the source
9586 For example, a package that generates an essential part
9587 which requires dependencies, and optional parts that
9588 which only require a recommendation, would separate those
9589 two sets of dependencies into two different fields.<footnote>
9590 At the time of writing, an example for this was the
9591 <package/xmms/ package, with Depends used for the xmms
9592 executable, Recommends for the plug-ins and Suggests for
9593 even more optional features provided by unzip.
9595 It can say in its <file>debian/rules</file>:
9597 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9598 -dRecommends <var>optionalpart anotheroptionalpart</var>
9600 and then in its main control file <file>debian/control</file>:
9603 Depends: ${shlibs:Pre-Depends}
9604 Recommends: ${shlibs:Recommends}
9610 Sources which produce several binary packages with
9611 different shared library dependency requirements can use
9612 the <tt>-p<var>varnameprefix</var></tt> option to override
9613 the default <tt>shlibs:</tt> prefix (one invocation of
9614 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9615 They can thus produce several sets of dependency
9616 variables, each of the form
9617 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9618 which can be referred to in the appropriate parts of the
9619 binary package control files.
9624 <sect1 id="pkg-dpkg-distaddfile">
9626 <prgn>dpkg-distaddfile</prgn> - adds a file to
9627 <file>debian/files</file>
9631 Some packages' uploads need to include files other than
9632 the source and binary package files.
9636 <prgn>dpkg-distaddfile</prgn> adds a file to the
9637 <file>debian/files</file> file so that it will be included in
9638 the <file>.changes</file> file when
9639 <prgn>dpkg-genchanges</prgn> is run.
9643 It is usually invoked from the <tt>binary</tt> target of
9644 <file>debian/rules</file>:
9646 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9648 The <var>filename</var> is relative to the directory where
9649 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9650 is usually the directory above the top level of the source
9651 tree. The <file>debian/rules</file> target should put the
9652 file there just before or just after calling
9653 <prgn>dpkg-distaddfile</prgn>.
9657 The <var>section</var> and <var>priority</var> are passed
9658 unchanged into the resulting <file>.changes</file> file.
9663 <sect1 id="pkg-dpkg-genchanges">
9665 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9670 This program is usually called by package-independent
9671 automatic building scripts such as
9672 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9677 It is usually called in the top level of a built source
9678 tree, and when invoked with no arguments will print out a
9679 straightforward <file>.changes</file> file based on the
9680 information in the source package's changelog and control
9681 file and the binary and source packages which should have
9687 <sect1 id="pkg-dpkg-parsechangelog">
9689 <prgn>dpkg-parsechangelog</prgn> - produces parsed
9690 representation of a changelog
9694 This program is used internally by
9695 <prgn>dpkg-source</prgn> et al. It may also occasionally
9696 be useful in <file>debian/rules</file> and elsewhere. It
9697 parses a changelog, <file>debian/changelog</file> by default,
9698 and prints a control-file format representation of the
9699 information in it to standard output.
9703 <sect1 id="pkg-dpkg-architecture">
9705 <prgn>dpkg-architecture</prgn> - information about the build and
9710 This program can be used manually, but is also invoked by
9711 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9712 to set environment or make variables which specify the build and
9713 host architecture for the package building process.
9718 <sect id="pkg-sourcetree">
9719 <heading>The Debianised source tree</heading>
9722 The source archive scheme described later is intended to
9723 allow a Debianised source tree with some associated control
9724 information to be reproduced and transported easily. The
9725 Debianised source tree is a version of the original program
9726 with certain files added for the benefit of the
9727 Debianisation process, and with any other changes required
9728 made to the rest of the source code and installation
9733 The extra files created for Debian are in the subdirectory
9734 <file>debian</file> of the top level of the Debianised source
9735 tree. They are described below.
9738 <sect1 id="pkg-debianrules">
9739 <heading><file>debian/rules</file> - the main building script</heading>
9742 See <ref id="debianrules">.
9747 <sect1 id="pkg-dpkgchangelog">
9748 <heading><file>debian/changelog</file></heading>
9751 See <ref id="dpkgchangelog">.
9755 It is recommended that the entire changelog be encoded in the
9756 <url id="http://www.cis.ohio-state.edu/cgi-bin/rfc/rfc2279.html" name="UTF-8">
9758 <url id="http://www.unicode.org/"
9759 name="Unicode">.<footnote>
9761 I think it is fairly obvious that we need to
9762 eventually transition to UTF-8 for our package
9763 infrastructure; it is really the only sane char-set in
9764 an international environment. Now, we can't switch to
9765 using UTF-8 for package control fields and the like
9766 until dpkg has better support, but one thing we can
9767 start doing today is requesting that Debian changelogs
9768 are UTF-8 encoded. At some point in time, we can start
9769 requiring them to do so.
9772 Checking for non-UTF8 characters in a changelog is
9773 trivial. Dump the file through
9774 <example>iconv -f utf-8 -t ucs-4</example>
9775 discard the output, and check the return
9776 value. If there are any characters in the stream
9777 which are invalid UTF-8 sequences, iconv will exit
9778 with an error code; and this will be the case for the
9779 vast majority of other character sets.
9784 <sect2><heading>Defining alternative changelog formats
9788 It is possible to use a different format to the standard
9789 one, by providing a parser for the format you wish to
9794 In order to have <tt>dpkg-parsechangelog</tt> run your
9795 parser, you must include a line within the last 40 lines
9796 of your file matching the Perl regular expression:
9797 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9798 parentheses should be the name of the format. For
9799 example, you might say:
9801 @@@ changelog-format: joebloggs @@@
9803 Changelog format names are non-empty strings of alphanumerics.
9807 If such a line exists then <tt>dpkg-parsechangelog</tt>
9808 will look for the parser as
9809 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9811 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9812 it is an error for it not to find it, or for it not to
9813 be an executable program. The default changelog format
9814 is <tt>dpkg</tt>, and a parser for it is provided with
9815 the <tt>dpkg</tt> package.
9819 The parser will be invoked with the changelog open on
9820 standard input at the start of the file. It should read
9821 the file (it may seek if it wishes) to determine the
9822 information required and return the parsed information
9823 to standard output in the form of a series of control
9824 fields in the standard format. By default it should
9825 return information about only the most recent version in
9826 the changelog; it should accept a
9827 <tt>-v<var>version</var></tt> option to return changes
9828 information from all versions present <em>strictly
9829 after</em> <var>version</var>, and it should then be an
9830 error for <var>version</var> not to be present in the
9836 <list compact="compact">
9837 <item><qref id="f-Source"><tt>Source</tt></qref></item>
9838 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
9839 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
9840 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
9841 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
9842 <item><qref id="f-Date"><tt>Date</tt></qref></item>
9843 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
9848 If several versions are being returned (due to the use
9849 of <tt>-v</tt>), the urgency value should be of the
9850 highest urgency code listed at the start of any of the
9851 versions requested followed by the concatenated
9852 (space-separated) comments from all the versions
9853 requested; the maintainer, version, distribution and
9854 date should always be from the most recent version.
9858 For the format of the <tt>Changes</tt> field see
9859 <ref id="f-Changes">.
9863 If the changelog format which is being parsed always or
9864 almost always leaves a blank line between individual
9865 change notes these blank lines should be stripped out,
9866 so as to make the resulting output compact.
9870 If the changelog format does not contain date or package
9871 name information this information should be omitted from
9872 the output. The parser should not attempt to synthesize
9873 it or find it from other sources.
9877 If the changelog does not have the expected format the
9878 parser should exit with a nonzero exit status, rather
9879 than trying to muddle through and possibly generating
9884 A changelog parser may not interact with the user at
9890 <sect1 id="pkg-srcsubstvars">
9891 <heading><file>debian/substvars</file> and variable substitutions</heading>
9894 See <ref id="substvars">.
9900 <heading><file>debian/files</file></heading>
9903 See <ref id="debianfiles">.
9907 <sect1><heading><file>debian/tmp</file>
9911 This is the canonical temporary location for the
9912 construction of binary packages by the <tt>binary</tt>
9913 target. The directory <file>tmp</file> serves as the root of
9914 the file system tree as it is being constructed (for
9915 example, by using the package's upstream makefiles install
9916 targets and redirecting the output there), and it also
9917 contains the <tt>DEBIAN</tt> subdirectory. See <ref
9918 id="pkg-bincreating">.
9922 If several binary packages are generated from the same
9923 source tree it is usual to use several
9924 <file>debian/tmp<var>something</var></file> directories, for
9925 example <file>tmp-a</file> or <file>tmp-doc</file>.
9929 Whatever <file>tmp</file> directories are created and used by
9930 <tt>binary</tt> must of course be removed by the
9931 <tt>clean</tt> target.</p></sect1>
9935 <sect id="pkg-sourcearchives"><heading>Source packages as archives
9939 As it exists on the FTP site, a Debian source package
9940 consists of three related files. You must have the right
9941 versions of all three to be able to use them.
9946 <tag>Debian source control file - <tt>.dsc</tt></tag>
9948 This file is a control file used by <prgn>dpkg-source</prgn>
9949 to extract a source package.
9950 See <ref id="debiansourcecontrolfiles">.
9954 Original source archive -
9956 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
9962 This is a compressed (with <tt>gzip -9</tt>)
9963 <prgn>tar</prgn> file containing the source code from
9964 the upstream authors of the program.
9969 Debianisation diff -
9971 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
9977 This is a unified context diff (<tt>diff -u</tt>)
9978 giving the changes which are required to turn the
9979 original source into the Debian source. These changes
9980 may only include editing and creating plain files.
9981 The permissions of files, the targets of symbolic
9982 links and the characteristics of special files or
9983 pipes may not be changed and no files may be removed
9988 All the directories in the diff must exist, except the
9989 <file>debian</file> subdirectory of the top of the source
9990 tree, which will be created by
9991 <prgn>dpkg-source</prgn> if necessary when unpacking.
9995 The <prgn>dpkg-source</prgn> program will
9996 automatically make the <file>debian/rules</file> file
9997 executable (see below).</p></item>
10002 If there is no original source code - for example, if the
10003 package is specially prepared for Debian or the Debian
10004 maintainer is the same as the upstream maintainer - the
10005 format is slightly different: then there is no diff, and the
10007 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10008 and preferably contains a directory named
10009 <file><var>package</var>-<var>version</var></file>.
10014 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10017 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10018 Debian source package. However, if it is not available it
10019 is possible to unpack a Debian source archive as follows:
10020 <enumlist compact="compact">
10023 Untar the tarfile, which will create a <file>.orig</file>
10027 <p>Rename the <file>.orig</file> directory to
10028 <file><var>package</var>-<var>version</var></file>.</p>
10032 Create the subdirectory <file>debian</file> at the top of
10033 the source tree.</p>
10035 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10037 <item><p>Untar the tarfile again if you want a copy of the original
10038 source code alongside the Debianised version.</p>
10043 It is not possible to generate a valid Debian source archive
10044 without using <prgn>dpkg-source</prgn>. In particular,
10045 attempting to use <prgn>diff</prgn> directly to generate the
10046 <file>.diff.gz</file> file will not work.
10050 <heading>Restrictions on objects in source packages</heading>
10053 The source package may not contain any hard links
10055 This is not currently detected when building source
10056 packages, but only when extracting
10060 Hard links may be permitted at some point in the
10061 future, but would require a fair amount of
10063 </footnote>, device special files, sockets or setuid or
10066 Setgid directories are allowed.
10071 The source packaging tools manage the changes between the
10072 original and Debianised source using <prgn>diff</prgn> and
10073 <prgn>patch</prgn>. Turning the original source tree as
10074 included in the <file>.orig.tar.gz</file> into the debianised
10075 source must not involve any changes which cannot be
10076 handled by these tools. Problematic changes which cause
10077 <prgn>dpkg-source</prgn> to halt with an error when
10078 building the source package are:
10079 <list compact="compact">
10080 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10082 <item><p>Changing the targets of symbolic links.</p>
10084 <item><p>Creating directories, other than <file>debian</file>.</p>
10086 <item><p>Changes to the contents of binary files.</p></item>
10087 </list> Changes which cause <prgn>dpkg-source</prgn> to
10088 print a warning but continue anyway are:
10089 <list compact="compact">
10092 Removing files, directories or symlinks.
10094 Renaming a file is not treated specially - it is
10095 seen as the removal of the old file (which
10096 generates a warning, but is otherwise ignored),
10097 and the creation of the new one.
10103 Changed text files which are missing the usual final
10104 newline (either in the original or the modified
10109 Changes which are not represented, but which are not detected by
10110 <prgn>dpkg-source</prgn>, are:
10111 <list compact="compact">
10112 <item><p>Changing the permissions of files (other than
10113 <file>debian/rules</file>) and directories.</p></item>
10118 The <file>debian</file> directory and <file>debian/rules</file>
10119 are handled specially by <prgn>dpkg-source</prgn> - before
10120 applying the changes it will create the <file>debian</file>
10121 directory, and afterwards it will make
10122 <file>debian/rules</file> world-executable.
10128 <appendix id="pkg-controlfields">
10129 <heading>Control files and their fields (from old Packaging Manual)</heading>
10132 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10133 data in a common format, known as control files. Binary and
10134 source packages have control data as do the <file>.changes</file>
10135 files which control the installation of uploaded files, and
10136 <prgn>dpkg</prgn>'s internal databases are in a similar
10141 <heading>Syntax of control files</heading>
10144 See <ref id="controlsyntax">.
10148 It is important to note that there are several fields which
10149 are optional as far as <prgn>dpkg</prgn> and the related
10150 tools are concerned, but which must appear in every Debian
10151 package, or whose omission may cause problems.
10156 <heading>List of fields</heading>
10159 See <ref id="controlfieldslist">.
10163 This section now contains only the fields that didn't belong
10164 to the Policy manual.
10167 <sect1 id="pkg-f-Filename">
10168 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10171 These fields in <tt>Packages</tt> files give the
10172 filename(s) of (the parts of) a package in the
10173 distribution directories, relative to the root of the
10174 Debian hierarchy. If the package has been split into
10175 several parts the parts are all listed in order, separated
10180 <sect1 id="pkg-f-Size">
10181 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10184 These fields in <file>Packages</file> files give the size (in
10185 bytes, expressed in decimal) and MD5 checksum of the
10186 file(s) which make(s) up a binary package in the
10187 distribution. If the package is split into several parts
10188 the values for the parts are listed in order, separated by
10193 <sect1 id="pkg-f-Status">
10194 <heading><tt>Status</tt></heading>
10197 This field in <prgn>dpkg</prgn>'s status file records
10198 whether the user wants a package installed, removed or
10199 left alone, whether it is broken (requiring
10200 re-installation) or not and what its current state on the
10201 system is. Each of these pieces of information is a
10206 <sect1 id="pkg-f-Config-Version">
10207 <heading><tt>Config-Version</tt></heading>
10210 If a package is not installed or not configured, this
10211 field in <prgn>dpkg</prgn>'s status file records the last
10212 version of the package which was successfully
10217 <sect1 id="pkg-f-Conffiles">
10218 <heading><tt>Conffiles</tt></heading>
10221 This field in <prgn>dpkg</prgn>'s status file contains
10222 information about the automatically-managed configuration
10223 files held by a package. This field should <em>not</em>
10224 appear anywhere in a package!
10229 <heading>Obsolete fields</heading>
10232 These are still recognized by <prgn>dpkg</prgn> but should
10233 not appear anywhere any more.
10235 <taglist compact="compact">
10237 <tag><tt>Revision</tt></tag>
10238 <tag><tt>Package-Revision</tt></tag>
10239 <tag><tt>Package_Revision</tt></tag>
10241 The Debian revision part of the package version was
10242 at one point in a separate control file field. This
10243 field went through several names.
10246 <tag><tt>Recommended</tt></tag>
10247 <item>Old name for <tt>Recommends</tt>.</item>
10249 <tag><tt>Optional</tt></tag>
10250 <item>Old name for <tt>Suggests</tt>.</item>
10252 <tag><tt>Class</tt></tag>
10253 <item>Old name for <tt>Priority</tt>.</item>
10262 <appendix id="pkg-conffiles">
10263 <heading>Configuration file handling (from old Packaging Manual)</heading>
10266 <prgn>dpkg</prgn> can do a certain amount of automatic
10267 handling of package configuration files.
10271 Whether this mechanism is appropriate depends on a number of
10272 factors, but basically there are two approaches to any
10273 particular configuration file.
10277 The easy method is to ship a best-effort configuration in the
10278 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10279 handle updates. If the user is unlikely to want to edit the
10280 file, but you need them to be able to without losing their
10281 changes, and a new package with a changed version of the file
10282 is only released infrequently, this is a good approach.
10286 The hard method is to build the configuration file from
10287 scratch in the <prgn>postinst</prgn> script, and to take the
10288 responsibility for fixing any mistakes made in earlier
10289 versions of the package automatically. This will be
10290 appropriate if the file is likely to need to be different on
10294 <sect><heading>Automatic handling of configuration files by
10299 A package may contain a control area file called
10300 <tt>conffiles</tt>. This file should be a list of filenames
10301 of configuration files needing automatic handling, separated
10302 by newlines. The filenames should be absolute pathnames,
10303 and the files referred to should actually exist in the
10308 When a package is upgraded <prgn>dpkg</prgn> will process
10309 the configuration files during the configuration stage,
10310 shortly before it runs the package's <prgn>postinst</prgn>
10315 For each file it checks to see whether the version of the
10316 file included in the package is the same as the one that was
10317 included in the last version of the package (the one that is
10318 being upgraded from); it also compares the version currently
10319 installed on the system with the one shipped with the last
10324 If neither the user nor the package maintainer has changed
10325 the file, it is left alone. If one or the other has changed
10326 their version, then the changed version is preferred - i.e.,
10327 if the user edits their file, but the package maintainer
10328 doesn't ship a different version, the user's changes will
10329 stay, silently, but if the maintainer ships a new version
10330 and the user hasn't edited it the new version will be
10331 installed (with an informative message). If both have
10332 changed their version the user is prompted about the problem
10333 and must resolve the differences themselves.
10337 The comparisons are done by calculating the MD5 message
10338 digests of the files, and storing the MD5 of the file as it
10339 was included in the most recent version of the package.
10343 When a package is installed for the first time
10344 <prgn>dpkg</prgn> will install the file that comes with it,
10345 unless that would mean overwriting a file already on the
10350 However, note that <prgn>dpkg</prgn> will <em>not</em>
10351 replace a conffile that was removed by the user (or by a
10352 script). This is necessary because with some programs a
10353 missing file produces an effect hard or impossible to
10354 achieve in another way, so that a missing file needs to be
10355 kept that way if the user did it.
10359 Note that a package should <em>not</em> modify a
10360 <prgn>dpkg</prgn>-handled conffile in its maintainer
10361 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10362 the user confusing and possibly dangerous options for
10363 conffile update when the package is upgraded.</p>
10366 <sect><heading>Fully-featured maintainer script configuration
10371 For files which contain site-specific information such as
10372 the hostname and networking details and so forth, it is
10373 better to create the file in the package's
10374 <prgn>postinst</prgn> script.
10378 This will typically involve examining the state of the rest
10379 of the system to determine values and other information, and
10380 may involve prompting the user for some information which
10381 can't be obtained some other way.
10385 When using this method there are a couple of important
10386 issues which should be considered:
10390 If you discover a bug in the program which generates the
10391 configuration file, or if the format of the file changes
10392 from one version to the next, you will have to arrange for
10393 the postinst script to do something sensible - usually this
10394 will mean editing the installed configuration file to remove
10395 the problem or change the syntax. You will have to do this
10396 very carefully, since the user may have changed the file,
10397 perhaps to fix the very problem that your script is trying
10398 to deal with - you will have to detect these situations and
10399 deal with them correctly.
10403 If you do go down this route it's probably a good idea to
10404 make the program that generates the configuration file(s) a
10405 separate program in <file>/usr/sbin</file>, by convention called
10406 <file><var>package</var>config</file> and then run that if
10407 appropriate from the post-installation script. The
10408 <tt><var>package</var>config</tt> program should not
10409 unquestioningly overwrite an existing configuration - if its
10410 mode of operation is geared towards setting up a package for
10411 the first time (rather than any arbitrary reconfiguration
10412 later) you should have it check whether the configuration
10413 already exists, and require a <tt>--force</tt> flag to
10414 overwrite it.</p></sect>
10417 <appendix id="pkg-alternatives"><heading>Alternative versions of
10418 an interface - <prgn>update-alternatives</prgn> (from old
10423 When several packages all provide different versions of the
10424 same program or file it is useful to have the system select a
10425 default, but to allow the system administrator to change it
10426 and have their decisions respected.
10430 For example, there are several versions of the <prgn>vi</prgn>
10431 editor, and there is no reason to prevent all of them from
10432 being installed at once, each under their own name
10433 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10434 Nevertheless it is desirable to have the name <tt>vi</tt>
10435 refer to something, at least by default.
10439 If all the packages involved cooperate, this can be done with
10440 <prgn>update-alternatives</prgn>.
10444 Each package provides its own version under its own name, and
10445 calls <prgn>update-alternatives</prgn> in its postinst to
10446 register its version (and again in its prerm to deregister
10451 See the man page <manref name="update-alternatives"
10452 section="8"> for details.
10456 If <prgn>update-alternatives</prgn> does not seem appropriate
10457 you may wish to consider using diversions instead.</p>
10460 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10461 package's version of a file (from old Packaging Manual)
10465 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10466 when it reinstalls the package it belongs to, and to have it
10467 put the file from the package somewhere else instead.
10471 This can be used locally to override a package's version of a
10472 file, or by one package to override another's version (or
10473 provide a wrapper for it).
10477 Before deciding to use a diversion, read <ref
10478 id="pkg-alternatives"> to see if you really want a diversion
10479 rather than several alternative versions of a program.
10483 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10484 and updated by a special program <prgn>dpkg-divert</prgn>.
10485 Please see <manref name="dpkg-divert" section="8"> for full
10486 details of its operation.
10490 When a package wishes to divert a file from another, it should
10491 call <prgn>dpkg-divert</prgn> in its preinst to add the
10492 diversion and rename the existing file. For example,
10493 supposing that a <prgn>smailwrapper</prgn> package wishes to
10494 install a wrapper around <file>/usr/sbin/smail</file>:
10496 if [ install = "$1" ]; then
10497 dpkg-divert --package smailwrapper --add --rename \
10498 --divert /usr/sbin/smail.real /usr/sbin/smail
10500 </example> Testing <tt>$1</tt> is necessary so that the script
10501 doesn't try to add the diversion again when
10502 <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
10503 smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
10504 copy of <file>/usr/sbin/smail</file> can bypass the diversion and
10505 get installed as the true version.
10509 The postrm has to do the reverse:
10511 if [ remove = "$1" ]; then
10512 dpkg-divert --package smailwrapper --remove --rename \
10513 --divert /usr/sbin/smail.real /usr/sbin/smail
10519 Do not attempt to divert a file which is vitally important for
10520 the system's operation - when using <prgn>dpkg-divert</prgn>
10521 there is a time, after it has been diverted but before
10522 <prgn>dpkg</prgn> has installed the new version, when the file
10523 does not exist.</p>
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