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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.
1476 The format of the <file>debian/changelog</file> allows the
1477 package building tools to discover which version of the package
1478 is being built and find out other release-specific information.
1482 That format is a series of entries like this:
1484 <example compact="compact">
1485 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1487 [optional blank line(s), stripped]
1489 * <var>change details</var>
1490 <var>more change details</var>
1492 [blank line(s), included in output of dpkg-parsechangelog]
1494 * <var>even more change details</var>
1496 [optional blank line(s), stripped]
1498 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1503 <var>package</var> and <var>version</var> are the source
1504 package name and version number.
1508 <var>distribution(s)</var> lists the distributions where
1509 this version should be installed when it is uploaded - it
1510 is copied to the <tt>Distribution</tt> field in the
1511 <file>.changes</file> file. See <ref id="f-Distribution">.
1515 <var>urgency</var> is the value for the <tt>Urgency</tt>
1516 field in the <file>.changes</file> file for the upload
1517 (see <ref id="f-Urgency">). It is not possible to specify
1518 an urgency containing commas; commas are used to separate
1519 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1520 <prgn>dpkg</prgn> changelog format (though there is
1521 currently only one useful <var>keyword</var>,
1526 The change details may in fact be any series of lines
1527 starting with at least two spaces, but conventionally each
1528 change starts with an asterisk and a separating space and
1529 continuation lines are indented so as to bring them in
1530 line with the start of the text above. Blank lines may be
1531 used here to separate groups of changes, if desired.
1535 If this upload resolves bugs recorded in the Bug Tracking
1536 System (BTS), they may be automatically closed on the
1537 inclusion of this package into the Debian archive by
1538 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1539 in the change details.<footnote>
1540 To be precise, the string should match the following
1541 Perl regular expression:
1543 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1545 Then all of the bug numbers listed will be closed by the
1546 archive maintenance script (<prgn>katie</prgn>) using the
1547 <var>version</var> of the changelog entry.
1549 This information is conveyed via the <tt>Closes</tt> field
1550 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1554 The maintainer name and email address used in the changelog
1555 should be the details of the person uploading <em>this</em>
1556 version. They are <em>not</em> necessarily those of the
1557 usual package maintainer. The information here will be
1558 copied to the <tt>Changed-By</tt> field in the
1559 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1560 and then later used to send an acknowledgement when the
1561 upload has been installed.
1565 The <var>date</var> must be in RFC822 format<footnote>
1566 This is generated by <tt>date -R</tt>.
1567 </footnote>; it must include the time zone specified
1568 numerically, with the time zone name or abbreviation
1569 optionally present as a comment in parentheses.
1573 The first "title" line with the package name must start
1574 at the left hand margin. The "trailer" line with the
1575 maintainer and date details must be preceded by exactly
1576 one space. The maintainer details and the date must be
1577 separated by exactly two spaces.
1581 For more information on placement of the changelog files
1582 within binary packages, please see <ref id="changelogs">.
1586 <sect id="dpkgcopyright">
1587 <heading>Copyright: <file>debian/copyright</file></heading>
1589 Every package must be accompanied by a verbatim copy of
1590 its copyright and distribution license in the file
1591 <file>/usr/share/doc/<var>package</var>/copyright</file>
1592 (see <ref id="copyrightfile"> for further details). Also see
1593 <ref id="pkgcopyright"> for further considerations relayed
1594 to copyrights for packages.
1598 <heading>Error trapping in makefiles</heading>
1601 When <prgn>make</prgn> invokes a command in a makefile
1602 (including your package's upstream makefiles and
1603 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1604 means that <prgn>sh</prgn>'s usual bad error handling
1605 properties apply: if you include a miniature script as one
1606 of the commands in your makefile you'll find that if you
1607 don't do anything about it then errors are not detected
1608 and <prgn>make</prgn> will blithely continue after
1613 Every time you put more than one shell command (this
1614 includes using a loop) in a makefile command you
1615 must make sure that errors are trapped. For
1616 simple compound commands, such as changing directory and
1617 then running a program, using <tt>&&</tt> rather
1618 than semicolon as a command separator is sufficient. For
1619 more complex commands including most loops and
1620 conditionals you should include a separate <tt>set -e</tt>
1621 command at the start of every makefile command that's
1622 actually one of these miniature shell scripts.
1626 <sect id="timestamps">
1627 <heading>Time Stamps</heading>
1629 Maintainers should preserve the modification times of the
1630 upstream source files in a package, as far as is reasonably
1632 The rationale is that there is some information conveyed
1633 by knowing the age of the file, for example, you could
1634 recognize that some documentation is very old by looking
1635 at the modification time, so it would be nice if the
1636 modification time of the upstream source would be
1642 <sect id="restrictions">
1643 <heading>Restrictions on objects in source packages</heading>
1646 The source package may not contain any hard links<footnote>
1648 This is not currently detected when building source
1649 packages, but only when extracting
1653 Hard links may be permitted at some point in the
1654 future, but would require a fair amount of
1657 </footnote>, device special files, sockets or setuid or
1658 setgid files.<footnote>
1659 Setgid directories are allowed.
1664 <sect id="debianrules">
1665 <heading>Main building script: <file>debian/rules</file></heading>
1668 This file must be an executable makefile, and contains the
1669 package-specific recipes for compiling the package and
1670 building binary package(s) from the source.
1674 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1675 so that it can be invoked by saying its name rather than
1676 invoking <prgn>make</prgn> explicitly.
1680 Since an interactive <file>debian/rules</file> script makes it
1681 impossible to auto-compile that package and also makes it
1682 hard for other people to reproduce the same binary
1683 package, all <em>required targets</em> MUST be
1684 non-interactive. At a minimum, required targets are the
1685 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1686 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1687 <em>binary-indep</em>, and <em>build</em>. It also follows
1688 that any target that these targets depend on must also be
1693 The targets are as follows (required unless stated otherwise):
1695 <tag><tt>build</tt></tag>
1698 The <tt>build</tt> target should perform all the
1699 configuration and compilation of the package.
1700 If a package has an interactive pre-build
1701 configuration routine, the Debianized source package
1702 must either be built after this has taken place (so
1703 that the binary package can be built without rerunning
1704 the configuration) or the configuration routine
1705 modified to become non-interactive. (The latter is
1706 preferable if there are architecture-specific features
1707 detected by the configuration routine.)
1711 For some packages, notably ones where the same
1712 source tree is compiled in different ways to produce
1713 two binary packages, the <tt>build</tt> target
1714 does not make much sense. For these packages it is
1715 good enough to provide two (or more) targets
1716 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1717 for each of the ways of building the package, and a
1718 <tt>build</tt> target that does nothing. The
1719 <tt>binary</tt> target will have to build the
1720 package in each of the possible ways and make the
1721 binary package out of each.
1725 The <tt>build</tt> target must not do anything
1726 that might require root privilege.
1730 The <tt>build</tt> target may need to run the
1731 <tt>clean</tt> target first - see below.
1735 When a package has a configuration and build routine
1736 which takes a long time, or when the makefiles are
1737 poorly designed, or when <tt>build</tt> needs to
1738 run <tt>clean</tt> first, it is a good idea to
1739 <tt>touch build</tt> when the build process is
1740 complete. This will ensure that if <tt>debian/rules
1741 build</tt> is run again it will not rebuild the whole
1743 Another common way to do this is for <tt>build</tt>
1744 to depend on <prgn>build-stamp</prgn> and to do
1745 nothing else, and for the <prgn>build-stamp</prgn>
1746 target to do the building and to <tt>touch
1747 build-stamp</tt> on completion. This is
1748 especially useful if the build routine creates a
1749 file or directory called <tt>build</tt>; in such a
1750 case, <tt>build</tt> will need to be listed as
1751 a phony target (i.e., as a dependency of the
1752 <tt>.PHONY</tt> target). See the documentation of
1753 <prgn>make</prgn> for more information on phony
1759 <tag><tt>build-arch</tt> (optional),
1760 <tt>build-indep</tt> (optional)
1764 A package may also provide both of the targets
1765 <tt>build-arch</tt> and <tt>build-indep</tt>.
1766 The <tt>build-arch</tt> target, if provided, should
1767 perform all the configuration and compilation required
1768 for producing all architecture-dependant binary packages
1769 (those packages for which the body of the
1770 <tt>Architecture</tt> field in <tt>debian/control</tt>
1771 is not <tt>all</tt>).
1772 Similarly, the <tt>build-indep</tt> target, if
1773 provided, should perform all the configuration and
1774 compilation required for producing all
1775 architecture-independent binary packages
1776 (those packages for which the body of the
1777 <tt>Architecture</tt> field in <tt>debian/control</tt>
1779 The <tt>build</tt> target should depend on those of the
1780 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1781 are provided in the rules file.
1785 If one or both of the targets <tt>build-arch</tt> and
1786 <tt>build-indep</tt> are not provided, then invoking
1787 <file>debian/rules</file> with one of the not-provided
1788 targets as arguments should produce a exit status code
1789 of 2. Usually this is provided automatically by make
1790 if the target is missing.
1794 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1795 must not do anything that might require root privilege.
1799 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1800 <tt>binary-indep</tt>
1804 The <tt>binary</tt> target must be all that is
1805 necessary for the user to build the binary package(s)
1806 produced from this source package. It is
1807 split into two parts: <prgn>binary-arch</prgn> builds
1808 the binary packages which are specific to a particular
1809 architecture, and <tt>binary-indep</tt> builds
1810 those which are not.
1813 <tt>binary</tt> may be (and commonly is) a target with
1814 no commands which simply depends on
1815 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1818 Both <tt>binary-*</tt> targets should depend on the
1819 <tt>build</tt> target, or on the appropriate
1820 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1821 provided, so that the package is built if it has not
1822 been already. It should then create the relevant
1823 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1824 make their control files and <prgn>dpkg-deb</prgn> to
1825 build them and place them in the parent of the top
1830 Both the <tt>binary-arch</tt> and
1831 <tt>binary-indep</tt> targets <em>must</em> exist.
1832 If one of them has nothing to do (which will always be
1833 the case if the source generates only a single binary
1834 package, whether architecture-dependent or not), it
1835 must still exist and must always succeed.
1839 The <tt>binary</tt> targets must be invoked as
1841 The <prgn>fakeroot</prgn> package often allows one
1842 to build a package correctly even without being
1848 <tag><tt>clean</tt></tag>
1851 This must undo any effects that the <tt>build</tt>
1852 and <tt>binary</tt> targets may have had, except
1853 that it should leave alone any output files created in
1854 the parent directory by a run of a <tt>binary</tt>
1859 If a <tt>build</tt> file is touched at the end of
1860 the <tt>build</tt> target, as suggested above, it
1861 should be removed as the first action that
1862 <tt>clean</tt> performs, so that running
1863 <tt>build</tt> again after an interrupted
1864 <tt>clean</tt> doesn't think that everything is
1869 The <tt>clean</tt> target may need to be
1870 invoked as root if <tt>binary</tt> has been
1871 invoked since the last <tt>clean</tt>, or if
1872 <tt>build</tt> has been invoked as root (since
1873 <tt>build</tt> may create directories, for
1878 <tag><tt>get-orig-source</tt> (optional)</tag>
1881 This target fetches the most recent version of the
1882 original source package from a canonical archive site
1883 (via FTP or WWW, for example), does any necessary
1884 rearrangement to turn it into the original source
1885 tar file format described below, and leaves it in the
1890 This target may be invoked in any directory, and
1891 should take care to clean up any temporary files it
1896 This target is optional, but providing it if
1897 possible is a good idea.
1901 <tag><tt>patch</tt> (optional)</tag>
1904 This target performs whatever additional actions are
1905 required to make the source ready for editing (unpacking
1906 additional upstream archives, applying patches, etc.).
1907 It is recommended to be implemented for any package where
1908 <tt>dpkg-source -x</tt> does not result in source ready
1909 for additional modification. See
1910 <ref id="readmesource">.
1916 The <tt>build</tt>, <tt>binary</tt> and
1917 <tt>clean</tt> targets must be invoked with the current
1918 directory being the package's top-level directory.
1923 Additional targets may exist in <file>debian/rules</file>,
1924 either as published or undocumented interfaces or for the
1925 package's internal use.
1929 The architectures we build on and build for are determined
1930 by <prgn>make</prgn> variables using the utility
1931 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
1932 You can determine the
1933 Debian architecture and the GNU style architecture
1934 specification string for the build machine (the machine type
1935 we are building on) as well as for the host machine (the
1936 machine type we are building for). Here is a list of
1937 supported <prgn>make</prgn> variables:
1938 <list compact="compact">
1940 <tt>DEB_*_ARCH</tt> (the Debian architecture)
1943 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
1944 specification string)
1947 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
1948 <tt>DEB_*_GNU_TYPE</tt>)
1951 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
1952 <tt>DEB_*_GNU_TYPE</tt>)
1954 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
1955 the build machine or <tt>HOST</tt> for specification of the
1960 Backward compatibility can be provided in the rules file
1961 by setting the needed variables to suitable default
1962 values; please refer to the documentation of
1963 <prgn>dpkg-architecture</prgn> for details.
1967 It is important to understand that the <tt>DEB_*_ARCH</tt>
1968 string only determines which Debian architecture we are
1969 building on or for. It should not be used to get the CPU
1970 or system information; the GNU style variables should be
1974 <sect1 id="debianrules-options">
1975 <heading><file>debian/rules</file> and
1976 <tt>DEB_BUILD_OPTIONS</tt></heading>
1979 Supporting the standardized environment variable
1980 <tt>DEB_BUILD_OPTIONS</tt> is recommended. This variable can
1981 contain several flags to change how a package is compiled and
1982 built. Each flag must be in the form <var>flag</var> or
1983 <var>flag</var>=<var>options</var>. If multiple flags are
1984 given, they must be separated by whitespace.<footnote>
1985 Some packages support any delimiter, but whitespace is the
1986 easiest to parse inside a makefile and avoids ambiguity with
1987 flag values that contain commas.
1989 <var>flag</var> must start with a lowercase letter
1990 (<tt>a-z</tt>) and consist only of lowercase letters,
1991 numbers (<tt>0-9</tt>), and the characters
1992 <tt>-</tt> and <tt>_</tt> (hyphen and underscore).
1993 <var>options</var> must not contain whitespace. The same
1994 tag should not be given multiple times with conflicting
1995 values. Package maintainers may assume that
1996 <tt>DEB_BUILD_OPTIONS</tt> will not contain conflicting tags.
2000 The meaning of the following tags has been standardized:
2004 The presence of this tag means that the package should
2005 be compiled with a minimum of optimization. For C
2006 programs, it is best to add <tt>-O0</tt> to
2007 <tt>CFLAGS</tt> (although this is usually the default).
2008 Some programs might fail to build or run at this level
2009 of optimization; it may be necessary to use
2010 <tt>-O1</tt>, for example.
2014 This tag means that the debugging symbols should not be
2015 stripped from the binary during installation, so that
2016 debugging information may be included in the package.
2018 <tag>parallel=n</tag>
2020 This tag means that the package should be built using up
2021 to <tt>n</tt> parallel processes if the package build
2022 system supports this.<footnote>
2023 Packages built with <tt>make</tt> can often implement
2024 this by passing the <tt>-j</tt><var>n</var> option to
2027 If the package build system does not support parallel
2028 builds, this string must be ignored. If the package
2029 build system only supports a lower level of concurrency
2030 than <var>n</var>, the package should be built using as
2031 many parallel processes as the package build system
2032 supports. It is up to the package maintainer to decide
2033 whether the package build times are long enough and the
2034 package build system is robust enough to make supporting
2035 parallel builds worthwhile.
2041 Unknown flags must be ignored by <file>debian/rules</file>.
2045 The following makefile snippet is an example of how one may
2046 implement the build options; you will probably have to
2047 massage this example in order to make it work for your
2049 <example compact="compact">
2052 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
2053 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
2054 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
2055 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
2057 ifneq (,$(filter noopt,$(DEB_BUILD_OPTIONS)))
2062 ifeq (,$(filter nostrip,$(DEB_BUILD_OPTIONS)))
2063 INSTALL_PROGRAM += -s
2065 ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2066 NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2067 MAKEFLAGS += -j$(NUMJOBS)
2074 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2075 <sect id="substvars">
2076 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2079 When <prgn>dpkg-gencontrol</prgn>,
2080 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2081 generate control files they perform variable substitutions
2082 on their output just before writing it. Variable
2083 substitutions have the form <tt>${<var>variable</var>}</tt>.
2084 The optional file <file>debian/substvars</file> contains
2085 variable substitutions to be used; variables can also be set
2086 directly from <file>debian/rules</file> using the <tt>-V</tt>
2087 option to the source packaging commands, and certain
2088 predefined variables are also available.
2092 The <file>debian/substvars</file> file is usually generated and
2093 modified dynamically by <file>debian/rules</file> targets, in
2094 which case it must be removed by the <tt>clean</tt> target.
2098 See <manref name="deb-substvars" section="5"> for full
2099 details about source variable substitutions, including the
2100 format of <file>debian/substvars</file>.</p>
2103 <sect id="debianwatch">
2104 <heading>Optional upstream source location: <file>debian/watch</file></heading>
2107 This is an optional, recommended control file for the
2108 <tt>uscan</tt> utility which defines how to automatically
2109 scan ftp or http sites for newly available updates of the
2110 package. This is used by <url id="
2111 http://dehs.alioth.debian.org/"> and other Debian QA tools
2112 to help with quality control and maintenance of the
2113 distribution as a whole.
2118 <sect id="debianfiles">
2119 <heading>Generated files list: <file>debian/files</file></heading>
2122 This file is not a permanent part of the source tree; it
2123 is used while building packages to record which files are
2124 being generated. <prgn>dpkg-genchanges</prgn> uses it
2125 when it generates a <file>.changes</file> file.
2129 It should not exist in a shipped source package, and so it
2130 (and any backup files or temporary files such as
2131 <file>files.new</file><footnote>
2132 <file>files.new</file> is used as a temporary file by
2133 <prgn>dpkg-gencontrol</prgn> and
2134 <prgn>dpkg-distaddfile</prgn> - they write a new
2135 version of <tt>files</tt> here before renaming it,
2136 to avoid leaving a corrupted copy if an error
2138 </footnote>) should be removed by the
2139 <tt>clean</tt> target. It may also be wise to
2140 ensure a fresh start by emptying or removing it at the
2141 start of the <tt>binary</tt> target.
2145 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2146 package, it adds an entry to <file>debian/files</file> for the
2147 <file>.deb</file> file that will be created when <tt>dpkg-deb
2148 --build</tt> is run for that binary package. So for most
2149 packages all that needs to be done with this file is to
2150 delete it in the <tt>clean</tt> target.
2154 If a package upload includes files besides the source
2155 package and any binary packages whose control files were
2156 made with <prgn>dpkg-gencontrol</prgn> then they should be
2157 placed in the parent of the package's top-level directory
2158 and <prgn>dpkg-distaddfile</prgn> should be called to add
2159 the file to the list in <file>debian/files</file>.</p>
2162 <sect id="embeddedfiles">
2163 <heading>Convenience copies of code</heading>
2166 Some software packages include in their distribution convenience
2167 copies of code from other software packages, generally so that
2168 users compiling from source don't have to download multiple
2169 packages. Debian packages should not make use of these
2170 convenience copies unless the included package is explicitly
2171 intended to be used in this way.<footnote>
2172 For example, parts of the GNU build system work like this.
2174 If the included code is already in the Debian archive in the
2175 form of a library, the Debian packaging should ensure that
2176 binary packages reference the libraries already in Debian and
2177 the convenience copy is not used. If the included code is not
2178 already in Debian, it should be packaged separately as a
2179 prerequisite if possible.
2181 Having multiple copies of the same code in Debian is
2182 inefficient, often creates either static linking or shared
2183 library conflicts, and, most importantly, increases the
2184 difficulty of handling security vulnerabilities in the
2190 <sect id="readmesource">
2191 <heading>Source package handling:
2192 <file>debian/README.source</file></heading>
2195 If running <prgn>dpkg-source -x</prgn> on a source package
2196 doesn't produce the source of the package, ready for editing,
2197 and allow one to make changes and run
2198 <prgn>dpkg-buildpackage</prgn> to produce a modified package
2199 without taking any additional steps, creating a
2200 <file>debian/README.source</file> documentation file is
2201 recommended. This file should explain how to do all of the
2204 <item>Generate the fully patched source, in a form ready for
2205 editing, that would be built to create Debian
2206 packages. Doing this with a <tt>patch</tt> target in
2207 <file>debian/rules</file> is recommended; see
2208 <ref id="debianrules">.</item>
2209 <item>Modify the source and save those modifications so that
2210 they will be applied when building the package.</item>
2211 <item>Remove source modifications that are currently being
2212 applied when building the package.</item>
2213 <item>Optionally, document what steps are necessary to
2214 upgrade the Debian source package to a new upstream version,
2215 if applicable.</item>
2217 This explanation should include specific commands and mention
2218 any additional required Debian packages. It should not assume
2219 familiarity with any specific Debian packaging system or patch
2224 This explanation may refer to a documentation file installed by
2225 one of the package's build dependencies provided that the
2226 referenced documentation clearly explains these tasks and is not
2227 a general reference manual.
2231 <file>debian/README.source</file> may also include any other
2232 information that would be helpful to someone modifying the
2233 source package. Even if the package doesn't fit the above
2234 description, maintainers are encouraged to document in a
2235 <file>debian/README.source</file> file any source package with a
2236 particularly complex or unintuitive source layout or build
2237 system (for example, a package that builds the same source
2238 multiple times to generate different binary packages).
2244 <chapt id="controlfields">
2245 <heading>Control files and their fields</heading>
2248 The package management system manipulates data represented in
2249 a common format, known as <em>control data</em>, stored in
2250 <em>control files</em>.
2251 Control files are used for source packages, binary packages and
2252 the <file>.changes</file> files which control the installation
2253 of uploaded files<footnote>
2254 <prgn>dpkg</prgn>'s internal databases are in a similar
2259 <sect id="controlsyntax">
2260 <heading>Syntax of control files</heading>
2263 A control file consists of one or more paragraphs of
2265 The paragraphs are also sometimes referred to as stanzas.
2267 The paragraphs are separated by blank lines. Some control
2268 files allow only one paragraph; others allow several, in
2269 which case each paragraph usually refers to a different
2270 package. (For example, in source packages, the first
2271 paragraph refers to the source package, and later paragraphs
2272 refer to binary packages generated from the source.)
2276 Each paragraph consists of a series of data fields; each
2277 field consists of the field name, followed by a colon and
2278 then the data/value associated with that field. It ends at
2279 the end of the (logical) line. Horizontal whitespace
2280 (spaces and tabs) may occur immediately before or after the
2281 value and is ignored there; it is conventional to put a
2282 single space after the colon. For example, a field might
2284 <example compact="compact">
2287 the field name is <tt>Package</tt> and the field value
2292 Many fields' values may span several lines; in this case
2293 each continuation line must start with a space or a tab.
2294 Any trailing spaces or tabs at the end of individual
2295 lines of a field value are ignored.
2299 In fields where it is specified that lines may not wrap,
2300 only a single line of data is allowed and whitespace is not
2301 significant in a field body. Whitespace must not appear
2302 inside names (of packages, architectures, files or anything
2303 else) or version numbers, or between the characters of
2304 multi-character version relationships.
2308 Field names are not case-sensitive, but it is usual to
2309 capitalize the field names using mixed case as shown below.
2313 Blank lines, or lines consisting only of spaces and tabs,
2314 are not allowed within field values or between fields - that
2315 would mean a new paragraph.
2320 <sect id="sourcecontrolfiles">
2321 <heading>Source package control files -- <file>debian/control</file></heading>
2324 The <file>debian/control</file> file contains the most vital
2325 (and version-independent) information about the source package
2326 and about the binary packages it creates.
2330 The first paragraph of the control file contains information about
2331 the source package in general. The subsequent sets each describe a
2332 binary package that the source tree builds.
2336 The fields in the general paragraph (the first one, for the source
2339 <list compact="compact">
2340 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2341 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2342 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2343 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2344 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2345 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2346 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2347 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2352 The fields in the binary package paragraphs are:
2354 <list compact="compact">
2355 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2356 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2357 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2358 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2359 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2360 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2361 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2362 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2367 The syntax and semantics of the fields are described below.
2373 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2374 generate control files for binary packages (see below), by
2375 <prgn>dpkg-genchanges</prgn> to generate the
2376 <tt>.changes</tt> file to accompany the upload, and by
2377 <prgn>dpkg-source</prgn> when it creates the
2378 <file>.dsc</file> source control file as part of a source
2379 archive. Many fields are permitted to span multiple lines in
2380 <file>debian/control</file> but not in any other control
2381 file. These tools are responsible for removing the line
2382 breaks from such fields when using fields from
2383 <file>debian/control</file> to generate other control files.
2387 The fields here may contain variable references - their
2388 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2389 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2390 when they generate output control files.
2391 See <ref id="substvars"> for details.
2396 <sect id="binarycontrolfiles">
2397 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2400 The <file>DEBIAN/control</file> file contains the most vital
2401 (and version-dependent) information about a binary package.
2405 The fields in this file are:
2407 <list compact="compact">
2408 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2409 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2410 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2411 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2412 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2413 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2414 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2415 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2416 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2417 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2418 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2419 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2424 <sect id="debiansourcecontrolfiles">
2425 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2428 This file contains a series of fields, identified and
2429 separated just like the fields in the control file of
2430 a binary package. The fields are listed below; their
2431 syntax is described above, in <ref id="pkg-controlfields">.
2433 <list compact="compact">
2434 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2435 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2436 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2437 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2438 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2439 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2440 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2441 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2442 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2443 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2444 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2449 The source package control file is generated by
2450 <prgn>dpkg-source</prgn> when it builds the source
2451 archive, from other files in the source package,
2452 described above. When unpacking, it is checked against
2453 the files and directories in the other parts of the
2459 <sect id="debianchangesfiles">
2460 <heading>Debian changes files -- <file>.changes</file></heading>
2463 The .changes files are used by the Debian archive maintenance
2464 software to process updates to packages. They contain one
2465 paragraph which contains information from the
2466 <tt>debian/control</tt> file and other data about the
2467 source package gathered via <tt>debian/changelog</tt>
2468 and <tt>debian/rules</tt>.
2472 The fields in this file are:
2474 <list compact="compact">
2475 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2476 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2477 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2478 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2479 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2480 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2481 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2482 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2483 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2484 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2485 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2486 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2487 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2488 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2493 <sect id="controlfieldslist">
2494 <heading>List of fields</heading>
2496 <sect1 id="f-Source">
2497 <heading><tt>Source</tt></heading>
2500 This field identifies the source package name.
2504 In <file>debian/control</file> or a <file>.dsc</file> file,
2505 this field must contain only the name of the source package.
2509 In a binary package control file or a <file>.changes</file>
2510 file, the source package name may be followed by a version
2511 number in parentheses<footnote>
2512 It is customary to leave a space after the package name
2513 if a version number is specified.
2515 This version number may be omitted (and is, by
2516 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2517 the <tt>Version</tt> field of the binary package in
2518 question. The field itself may be omitted from a binary
2519 package control file when the source package has the same
2520 name and version as the binary package.
2524 <sect1 id="f-Maintainer">
2525 <heading><tt>Maintainer</tt></heading>
2528 The package maintainer's name and email address. The name
2529 should come first, then the email address inside angle
2530 brackets <tt><></tt> (in RFC822 format).
2534 If the maintainer's name contains a full stop then the
2535 whole field will not work directly as an email address due
2536 to a misfeature in the syntax specified in RFC822; a
2537 program using this field as an address must check for this
2538 and correct the problem if necessary (for example by
2539 putting the name in round brackets and moving it to the
2540 end, and bringing the email address forward).
2544 <sect1 id="f-Uploaders">
2545 <heading><tt>Uploaders</tt></heading>
2548 List of the names and email addresses of co-maintainers of
2549 the package, if any. If the package has other maintainers
2550 beside the one named in the
2551 <qref id="f-Maintainer">Maintainer field</qref>, their
2552 names and email addresses should be listed here. The
2553 format is the same as that of the Maintainer tag, and
2554 multiple entries should be comma separated. Currently,
2555 this field is restricted to a single line of data. This
2556 is an optional field.
2559 Any parser that interprets the Uploaders field in
2560 <file>debian/control</file> must permit it to span multiple
2561 lines. Line breaks in an Uploaders field that spans multiple
2562 lines are not significant and the semantics of the field are
2563 the same as if the line breaks had not been present.
2567 <sect1 id="f-Changed-By">
2568 <heading><tt>Changed-By</tt></heading>
2571 The name and email address of the person who changed the
2572 said package. Usually the name of the maintainer.
2573 All the rules for the Maintainer field apply here, too.
2577 <sect1 id="f-Section">
2578 <heading><tt>Section</tt></heading>
2581 This field specifies an application area into which the package
2582 has been classified. See <ref id="subsections">.
2586 When it appears in the <file>debian/control</file> file,
2587 it gives the value for the subfield of the same name in
2588 the <tt>Files</tt> field of the <file>.changes</file> file.
2589 It also gives the default for the same field in the binary
2594 <sect1 id="f-Priority">
2595 <heading><tt>Priority</tt></heading>
2598 This field represents how important that it is that the user
2599 have the package installed. See <ref id="priorities">.
2603 When it appears in the <file>debian/control</file> file,
2604 it gives the value for the subfield of the same name in
2605 the <tt>Files</tt> field of the <file>.changes</file> file.
2606 It also gives the default for the same field in the binary
2611 <sect1 id="f-Package">
2612 <heading><tt>Package</tt></heading>
2615 The name of the binary package.
2619 Package names must consist only of lower case letters
2620 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
2621 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
2622 They must be at least two characters long and must start
2623 with an alphanumeric character.
2627 <sect1 id="f-Architecture">
2628 <heading><tt>Architecture</tt></heading>
2631 Depending on context and the control file used, the
2632 <tt>Architecture</tt> field can include the following sets of
2635 <item>A unique single word identifying a Debian machine
2636 architecture, see <ref id="arch-spec">.
2637 <item><tt>all</tt>, which indicates an
2638 architecture-independent package.
2639 <item><tt>any</tt>, which indicates a package available
2640 for building on any architecture.
2641 <item><tt>source</tt>, which indicates a source package.
2646 In the main <file>debian/control</file> file in the source
2647 package, or in the source package control file
2648 <file>.dsc</file>, one may specify a list of architectures
2649 separated by spaces, or the special values <tt>any</tt> or
2654 Specifying <tt>any</tt> indicates that the source package
2655 isn't dependent on any particular architecture and should
2656 compile fine on any one. The produced binary package(s)
2657 will be specific to whatever the current build architecture
2659 This is the most often used setting, and is recommended
2660 for new packages that aren't <tt>Architecture: all</tt>.
2665 Specifying a list of architectures indicates that the source
2666 will build an architecture-dependent package, and will only
2667 work correctly on the listed architectures.<footnote>
2668 This is a setting used for a minority of cases where the
2669 program is not portable. Generally, it should not be used
2675 In a <file>.changes</file> file, the <tt>Architecture</tt>
2676 field lists the architecture(s) of the package(s)
2677 currently being uploaded. This will be a list; if the
2678 source for the package is also being uploaded, the special
2679 entry <tt>source</tt> is also present.
2683 See <ref id="debianrules"> for information how to get the
2684 architecture for the build process.
2688 <sect1 id="f-Essential">
2689 <heading><tt>Essential</tt></heading>
2692 This is a boolean field which may occur only in the
2693 control file of a binary package or in a per-package fields
2694 paragraph of a main source control data file.
2698 If set to <tt>yes</tt> then the package management system
2699 will refuse to remove the package (upgrading and replacing
2700 it is still possible). The other possible value is <tt>no</tt>,
2701 which is the same as not having the field at all.
2706 <heading>Package interrelationship fields:
2707 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2708 <tt>Recommends</tt>, <tt>Suggests</tt>,
2709 <tt>Breaks</tt>, <tt>Conflicts</tt>,
2710 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2714 These fields describe the package's relationships with
2715 other packages. Their syntax and semantics are described
2716 in <ref id="relationships">.</p>
2719 <sect1 id="f-Standards-Version">
2720 <heading><tt>Standards-Version</tt></heading>
2723 The most recent version of the standards (the policy
2724 manual and associated texts) with which the package
2729 The version number has four components: major and minor
2730 version number and major and minor patch level. When the
2731 standards change in a way that requires every package to
2732 change the major number will be changed. Significant
2733 changes that will require work in many packages will be
2734 signaled by a change to the minor number. The major patch
2735 level will be changed for any change to the meaning of the
2736 standards, however small; the minor patch level will be
2737 changed when only cosmetic, typographical or other edits
2738 are made which neither change the meaning of the document
2739 nor affect the contents of packages.
2743 Thus only the first three components of the policy version
2744 are significant in the <em>Standards-Version</em> control
2745 field, and so either these three components or the all
2746 four components may be specified.<footnote>
2747 In the past, people specified the full version number
2748 in the Standards-Version field, for example "2.3.0.0".
2749 Since minor patch-level changes don't introduce new
2750 policy, it was thought it would be better to relax
2751 policy and only require the first 3 components to be
2752 specified, in this example "2.3.0". All four
2753 components may still be used if someone wishes to do so.
2759 <sect1 id="f-Version">
2760 <heading><tt>Version</tt></heading>
2763 The version number of a package. The format is:
2764 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2768 The three components here are:
2770 <tag><var>epoch</var></tag>
2773 This is a single (generally small) unsigned integer. It
2774 may be omitted, in which case zero is assumed. If it is
2775 omitted then the <var>upstream_version</var> may not
2780 It is provided to allow mistakes in the version numbers
2781 of older versions of a package, and also a package's
2782 previous version numbering schemes, to be left behind.
2786 <tag><var>upstream_version</var></tag>
2789 This is the main part of the version number. It is
2790 usually the version number of the original ("upstream")
2791 package from which the <file>.deb</file> file has been made,
2792 if this is applicable. Usually this will be in the same
2793 format as that specified by the upstream author(s);
2794 however, it may need to be reformatted to fit into the
2795 package management system's format and comparison
2800 The comparison behavior of the package management system
2801 with respect to the <var>upstream_version</var> is
2802 described below. The <var>upstream_version</var>
2803 portion of the version number is mandatory.
2807 The <var>upstream_version</var> may contain only
2808 alphanumerics<footnote>
2809 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2811 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2812 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
2813 tilde) and should start with a digit. If there is no
2814 <var>debian_revision</var> then hyphens are not allowed;
2815 if there is no <var>epoch</var> then colons are not
2820 <tag><var>debian_revision</var></tag>
2823 This part of the version number specifies the version of
2824 the Debian package based on the upstream version. It
2825 may contain only alphanumerics and the characters
2826 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
2827 tilde) and is compared in the same way as the
2828 <var>upstream_version</var> is.
2832 It is optional; if it isn't present then the
2833 <var>upstream_version</var> may not contain a hyphen.
2834 This format represents the case where a piece of
2835 software was written specifically to be turned into a
2836 Debian package, and so there is only one "debianisation"
2837 of it and therefore no revision indication is required.
2841 It is conventional to restart the
2842 <var>debian_revision</var> at <tt>1</tt> each time the
2843 <var>upstream_version</var> is increased.
2847 The package management system will break the version
2848 number apart at the last hyphen in the string (if there
2849 is one) to determine the <var>upstream_version</var> and
2850 <var>debian_revision</var>. The absence of a
2851 <var>debian_revision</var> is equivalent to a
2852 <var>debian_revision</var> of <tt>0</tt>.
2859 When comparing two version numbers, first the <var>epoch</var>
2860 of each are compared, then the <var>upstream_version</var> if
2861 <var>epoch</var> is equal, and then <var>debian_revision</var>
2862 if <var>upstream_version</var> is also equal.
2863 <var>epoch</var> is compared numerically. The
2864 <var>upstream_version</var> and <var>debian_revision</var>
2865 parts are compared by the package management system using the
2866 following algorithm:
2870 The strings are compared from left to right.
2874 First the initial part of each string consisting entirely of
2875 non-digit characters is determined. These two parts (one of
2876 which may be empty) are compared lexically. If a difference
2877 is found it is returned. The lexical comparison is a
2878 comparison of ASCII values modified so that all the letters
2879 sort earlier than all the non-letters and so that a tilde
2880 sorts before anything, even the end of a part. For example,
2881 the following parts are in sorted order from earliest to
2882 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
2883 <tt>a</tt>.<footnote>
2884 One common use of <tt>~</tt> is for upstream pre-releases.
2885 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
2886 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
2891 Then the initial part of the remainder of each string which
2892 consists entirely of digit characters is determined. The
2893 numerical values of these two parts are compared, and any
2894 difference found is returned as the result of the comparison.
2895 For these purposes an empty string (which can only occur at
2896 the end of one or both version strings being compared) counts
2901 These two steps (comparing and removing initial non-digit
2902 strings and initial digit strings) are repeated until a
2903 difference is found or both strings are exhausted.
2907 Note that the purpose of epochs is to allow us to leave behind
2908 mistakes in version numbering, and to cope with situations
2909 where the version numbering scheme changes. It is
2910 <em>not</em> intended to cope with version numbers containing
2911 strings of letters which the package management system cannot
2912 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
2913 silly orderings (the author of this manual has heard of a
2914 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
2915 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
2916 <tt>2</tt> and so forth).
2920 <sect1 id="f-Description">
2921 <heading><tt>Description</tt></heading>
2924 In a source or binary control file, the <tt>Description</tt>
2925 field contains a description of the binary package, consisting
2926 of two parts, the synopsis or the short description, and the
2927 long description. The field's format is as follows:
2932 Description: <single line synopsis>
2933 <extended description over several lines>
2938 The lines in the extended description can have these formats:
2944 Those starting with a single space are part of a paragraph.
2945 Successive lines of this form will be word-wrapped when
2946 displayed. The leading space will usually be stripped off.
2950 Those starting with two or more spaces. These will be
2951 displayed verbatim. If the display cannot be panned
2952 horizontally, the displaying program will line wrap them "hard"
2953 (i.e., without taking account of word breaks). If it can they
2954 will be allowed to trail off to the right. None, one or two
2955 initial spaces may be deleted, but the number of spaces
2956 deleted from each line will be the same (so that you can have
2957 indenting work correctly, for example).
2961 Those containing a single space followed by a single full stop
2962 character. These are rendered as blank lines. This is the
2963 <em>only</em> way to get a blank line<footnote>
2964 Completely empty lines will not be rendered as blank lines.
2965 Instead, they will cause the parser to think you're starting
2966 a whole new record in the control file, and will therefore
2967 likely abort with an error.
2972 Those containing a space, a full stop and some more characters.
2973 These are for future expansion. Do not use them.
2979 Do not use tab characters. Their effect is not predictable.
2983 See <ref id="descriptions"> for further information on this.
2987 In a <file>.changes</file> file, the <tt>Description</tt> field
2988 contains a summary of the descriptions for the packages being
2993 The part of the field before the first newline is empty;
2994 thereafter each line has the name of a binary package and
2995 the summary description line from that binary package.
2996 Each line is indented by one space.
3001 <sect1 id="f-Distribution">
3002 <heading><tt>Distribution</tt></heading>
3005 In a <file>.changes</file> file or parsed changelog output
3006 this contains the (space-separated) name(s) of the
3007 distribution(s) where this version of the package should
3008 be installed. Valid distributions are determined by the
3009 archive maintainers.<footnote>
3010 Current distribution names are:
3011 <taglist compact="compact">
3012 <tag><em>stable</em></tag>
3014 This is the current "released" version of Debian
3015 GNU/Linux. Once the distribution is
3016 <em>stable</em> only security fixes and other
3017 major bug fixes are allowed. When changes are
3018 made to this distribution, the release number is
3019 increased (for example: 2.2r1 becomes 2.2r2 then
3023 <tag><em>unstable</em></tag>
3025 This distribution value refers to the
3026 <em>developmental</em> part of the Debian
3027 distribution tree. New packages, new upstream
3028 versions of packages and bug fixes go into the
3029 <em>unstable</em> directory tree. Download from
3030 this distribution at your own risk.
3033 <tag><em>testing</em></tag>
3035 This distribution value refers to the
3036 <em>testing</em> part of the Debian distribution
3037 tree. It receives its packages from the
3038 unstable distribution after a short time lag to
3039 ensure that there are no major issues with the
3040 unstable packages. It is less prone to breakage
3041 than unstable, but still risky. It is not
3042 possible to upload packages directly to
3046 <tag><em>frozen</em></tag>
3048 From time to time, the <em>testing</em>
3049 distribution enters a state of "code-freeze" in
3050 anticipation of release as a <em>stable</em>
3051 version. During this period of testing only
3052 fixes for existing or newly-discovered bugs will
3053 be allowed. The exact details of this stage are
3054 determined by the Release Manager.
3057 <tag><em>experimental</em></tag>
3059 The packages with this distribution value are
3060 deemed by their maintainers to be high
3061 risk. Oftentimes they represent early beta or
3062 developmental packages from various sources that
3063 the maintainers want people to try, but are not
3064 ready to be a part of the other parts of the
3065 Debian distribution tree. Download at your own
3071 You should list <em>all</em> distributions that the
3072 package should be installed into.
3076 More information is available in the Debian Developer's
3077 Reference, section "The Debian archive".
3084 <heading><tt>Date</tt></heading>
3087 This field includes the date the package was built or last edited.
3091 The value of this field is usually extracted from the
3092 <file>debian/changelog</file> file - see
3093 <ref id="dpkgchangelog">).
3097 <sect1 id="f-Format">
3098 <heading><tt>Format</tt></heading>
3101 This field specifies a format revision for the file.
3102 The most current format described in the Policy Manual
3103 is version <strong>1.5</strong>. The syntax of the
3104 format value is the same as that of a package version
3105 number except that no epoch or Debian revision is allowed
3106 - see <ref id="f-Version">.
3110 <sect1 id="f-Urgency">
3111 <heading><tt>Urgency</tt></heading>
3114 This is a description of how important it is to upgrade to
3115 this version from previous ones. It consists of a single
3116 keyword taking one of the values <tt>low</tt>,
3117 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3118 <tt>critical</tt><footnote>
3119 Other urgency values are supported with configuration
3120 changes in the archive software but are not used in Debian.
3121 The urgency affects how quickly a package will be considered
3122 for inclusion into the <tt>testing</tt> distribution and
3123 gives an indication of the importance of any fixes included
3124 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3125 treated as synonymous.
3126 </footnote> (not case-sensitive) followed by an optional
3127 commentary (separated by a space) which is usually in
3128 parentheses. For example:
3131 Urgency: low (HIGH for users of diversions)
3137 The value of this field is usually extracted from the
3138 <file>debian/changelog</file> file - see
3139 <ref id="dpkgchangelog">.
3143 <sect1 id="f-Changes">
3144 <heading><tt>Changes</tt></heading>
3147 This field contains the human-readable changes data, describing
3148 the differences between the last version and the current one.
3152 There should be nothing in this field before the first
3153 newline; all the subsequent lines must be indented by at
3154 least one space; blank lines must be represented by a line
3155 consisting only of a space and a full stop.
3159 The value of this field is usually extracted from the
3160 <file>debian/changelog</file> file - see
3161 <ref id="dpkgchangelog">).
3165 Each version's change information should be preceded by a
3166 "title" line giving at least the version, distribution(s)
3167 and urgency, in a human-readable way.
3171 If data from several versions is being returned the entry
3172 for the most recent version should be returned first, and
3173 entries should be separated by the representation of a
3174 blank line (the "title" line may also be followed by the
3175 representation of blank line).
3179 <sect1 id="f-Binary">
3180 <heading><tt>Binary</tt></heading>
3183 This field is a list of binary packages.
3187 When it appears in the <file>.dsc</file> file it is the list
3188 of binary packages which a source package can produce. It
3189 does not necessarily produce all of these binary packages
3190 for every architecture. The source control file doesn't
3191 contain details of which architectures are appropriate for
3192 which of the binary packages.
3196 When it appears in a <file>.changes</file> file it lists the
3197 names of the binary packages actually being uploaded.
3201 The syntax is a list of binary packages separated by
3203 A space after each comma is conventional.
3204 </footnote>. Currently the packages must be separated using
3205 only spaces in the <file>.changes</file> file.
3209 <sect1 id="f-Installed-Size">
3210 <heading><tt>Installed-Size</tt></heading>
3213 This field appears in the control files of binary
3214 packages, and in the <file>Packages</file> files. It gives
3215 the total amount of disk space required to install the
3220 The disk space is represented in kilobytes as a simple
3225 <sect1 id="f-Files">
3226 <heading><tt>Files</tt></heading>
3229 This field contains a list of files with information about
3230 each one. The exact information and syntax varies with
3231 the context. In all cases the part of the field
3232 contents on the same line as the field name is empty. The
3233 remainder of the field is one line per file, each line
3234 being indented by one space and containing a number of
3235 sub-fields separated by spaces.
3239 In the <file>.dsc</file> file, each line contains the MD5
3240 checksum, size and filename of the tar file and (if applicable)
3241 diff file which make up the remainder of the source
3243 That is, the parts which are not the <tt>.dsc</tt>.
3245 The exact forms of the filenames are described
3246 in <ref id="pkg-sourcearchives">.
3250 In the <file>.changes</file> file this contains one line per
3251 file being uploaded. Each line contains the MD5 checksum,
3252 size, section and priority and the filename.
3253 The <qref id="f-Section">section</qref>
3254 and <qref id="f-Priority">priority</qref>
3255 are the values of the corresponding fields in
3256 the main source control file. If no section or priority is
3257 specified then <tt>-</tt> should be used, though section
3258 and priority values must be specified for new packages to
3259 be installed properly.
3263 The special value <tt>byhand</tt> for the section in a
3264 <tt>.changes</tt> file indicates that the file in question
3265 is not an ordinary package file and must by installed by
3266 hand by the distribution maintainers. If the section is
3267 <tt>byhand</tt> the priority should be <tt>-</tt>.
3271 If a new Debian revision of a package is being shipped and
3272 no new original source archive is being distributed the
3273 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3274 entry for the original source archive
3275 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
3276 but the <file>.changes</file> file should leave it out. In
3277 this case the original source archive on the distribution
3278 site must match exactly, byte-for-byte, the original
3279 source archive which was used to generate the
3280 <file>.dsc</file> file and diff which are being uploaded.</p>
3283 <sect1 id="f-Closes">
3284 <heading><tt>Closes</tt></heading>
3287 A space-separated list of bug report numbers that the upload
3288 governed by the .changes file closes.
3292 <sect1 id="f-Homepage">
3293 <heading><tt>Homepage</tt></heading>
3296 The URL of the web site for this package, preferably (when
3297 applicable) the site from which the original source can be
3298 obtained and any additional upstream documentation or
3299 information may be found. The content of this field is a
3300 simple URL without any surrounding characters such as
3308 <heading>User-defined fields</heading>
3311 Additional user-defined fields may be added to the
3312 source package control file. Such fields will be
3313 ignored, and not copied to (for example) binary or
3314 source package control files or upload control files.
3318 If you wish to add additional unsupported fields to
3319 these output files you should use the mechanism
3324 Fields in the main source control information file with
3325 names starting <tt>X</tt>, followed by one or more of
3326 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3327 be copied to the output files. Only the part of the
3328 field name after the hyphen will be used in the output
3329 file. Where the letter <tt>B</tt> is used the field
3330 will appear in binary package control files, where the
3331 letter <tt>S</tt> is used in source package control
3332 files and where <tt>C</tt> is used in upload control
3333 (<tt>.changes</tt>) files.
3337 For example, if the main source information control file
3340 XBS-Comment: I stand between the candle and the star.
3342 then the binary and source package control files will contain the
3345 Comment: I stand between the candle and the star.
3354 <chapt id="maintainerscripts">
3355 <heading>Package maintainer scripts and installation procedure</heading>
3358 <heading>Introduction to package maintainer scripts</heading>
3361 It is possible to supply scripts as part of a package which
3362 the package management system will run for you when your
3363 package is installed, upgraded or removed.
3367 These scripts are the files <prgn>preinst</prgn>,
3368 <prgn>postinst</prgn>, <prgn>prerm</prgn> and
3369 <prgn>postrm</prgn> in the control area of the package.
3370 They must be proper executable files; if they are scripts
3371 (which is recommended), they must start with the usual
3372 <tt>#!</tt> convention. They should be readable and
3373 executable by anyone, and must not be world-writable.
3377 The package management system looks at the exit status from
3378 these scripts. It is important that they exit with a
3379 non-zero status if there is an error, so that the package
3380 management system can stop its processing. For shell
3381 scripts this means that you <em>almost always</em> need to
3382 use <tt>set -e</tt> (this is usually true when writing shell
3383 scripts, in fact). It is also important, of course, that
3384 they don't exit with a non-zero status if everything went
3389 Additionally, packages interacting with users using
3390 <tt>debconf</tt> in the <prgn>postinst</prgn> script should
3391 install a <prgn>config</prgn> script in the control area,
3392 see <ref id="maintscriptprompt"> for details.
3396 When a package is upgraded a combination of the scripts from
3397 the old and new packages is called during the upgrade
3398 procedure. If your scripts are going to be at all
3399 complicated you need to be aware of this, and may need to
3400 check the arguments to your scripts.
3404 Broadly speaking the <prgn>preinst</prgn> is called before
3405 (a particular version of) a package is installed, and the
3406 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3407 before (a version of) a package is removed and the
3408 <prgn>postrm</prgn> afterwards.
3412 Programs called from maintainer scripts should not normally
3413 have a path prepended to them. Before installation is
3414 started, the package management system checks to see if the
3415 programs <prgn>ldconfig</prgn>,
3416 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3417 and <prgn>update-rc.d</prgn> can be found via the
3418 <tt>PATH</tt> environment variable. Those programs, and any
3419 other program that one would expect to be in the
3420 <tt>PATH</tt>, should thus be invoked without an absolute
3421 pathname. Maintainer scripts should also not reset the
3422 <tt>PATH</tt>, though they might choose to modify it by
3423 prepending or appending package-specific directories. These
3424 considerations really apply to all shell scripts.</p>
3427 <sect id="idempotency">
3428 <heading>Maintainer scripts idempotency</heading>
3431 It is necessary for the error recovery procedures that the
3432 scripts be idempotent. This means that if it is run
3433 successfully, and then it is called again, it doesn't bomb
3434 out or cause any harm, but just ensures that everything is
3435 the way it ought to be. If the first call failed, or
3436 aborted half way through for some reason, the second call
3437 should merely do the things that were left undone the first
3438 time, if any, and exit with a success status if everything
3440 This is so that if an error occurs, the user interrupts
3441 <prgn>dpkg</prgn> or some other unforeseen circumstance
3442 happens you don't leave the user with a badly-broken
3443 package when <prgn>dpkg</prgn> attempts to repeat the
3449 <sect id="controllingterminal">
3450 <heading>Controlling terminal for maintainer scripts</heading>
3453 The maintainer scripts are guaranteed to run with a
3454 controlling terminal and can interact with the user.
3455 Because these scripts may be executed with standard output
3456 redirected into a pipe for logging purposes, Perl scripts
3457 should set unbuffered output by setting <tt>$|=1</tt> so
3458 that the output is printed immediately rather than being
3462 <sect id="exitstatus">
3463 <heading>Exit status</heading>
3466 Each script must return a zero exit status for
3467 success, or a nonzero one for failure, since the package
3468 management system looks for the exit status of these scripts
3469 and determines what action to take next based on that datum.
3473 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3478 <list compact="compact">
3480 <var>new-preinst</var> <tt>install</tt>
3483 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3486 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3489 <var>old-preinst</var> <tt>abort-upgrade</tt>
3490 <var>new-version</var>
3495 <list compact="compact">
3497 <var>postinst</var> <tt>configure</tt>
3498 <var>most-recently-configured-version</var>
3501 <var>old-postinst</var> <tt>abort-upgrade</tt>
3502 <var>new-version</var>
3505 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3506 <tt>in-favour</tt> <var>package</var>
3507 <var>new-version</var>
3510 <var>postinst</var> <tt>abort-remove</tt>
3513 <var>deconfigured's-postinst</var>
3514 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3515 <var>failed-install-package</var> <var>version</var>
3516 [<tt>removing</tt> <var>conflicting-package</var>
3522 <list compact="compact">
3524 <var>prerm</var> <tt>remove</tt>
3527 <var>old-prerm</var> <tt>upgrade</tt>
3528 <var>new-version</var>
3531 <var>new-prerm</var> <tt>failed-upgrade</tt>
3532 <var>old-version</var>
3535 <var>conflictor's-prerm</var> <tt>remove</tt>
3536 <tt>in-favour</tt> <var>package</var>
3537 <var>new-version</var>
3540 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3541 <tt>in-favour</tt> <var>package-being-installed</var>
3542 <var>version</var> [<tt>removing</tt>
3543 <var>conflicting-package</var>
3549 <list compact="compact">
3551 <var>postrm</var> <tt>remove</tt>
3554 <var>postrm</var> <tt>purge</tt>
3557 <var>old-postrm</var> <tt>upgrade</tt>
3558 <var>new-version</var>
3561 <var>new-postrm</var> <tt>failed-upgrade</tt>
3562 <var>old-version</var>
3565 <var>new-postrm</var> <tt>abort-install</tt>
3568 <var>new-postrm</var> <tt>abort-install</tt>
3569 <var>old-version</var>
3572 <var>new-postrm</var> <tt>abort-upgrade</tt>
3573 <var>old-version</var>
3576 <var>disappearer's-postrm</var> <tt>disappear</tt>
3577 <var>overwriter</var>
3578 <var>overwriter-version</var>
3584 <sect id="unpackphase">
3585 <heading>Details of unpack phase of installation or upgrade</heading>
3588 The procedure on installation/upgrade/overwrite/disappear
3589 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3590 stage of <tt>dpkg --install</tt>) is as follows. In each
3591 case, if a major error occurs (unless listed below) the
3592 actions are, in general, run backwards - this means that the
3593 maintainer scripts are run with different arguments in
3594 reverse order. These are the "error unwind" calls listed
3601 If a version of the package is already installed, call
3602 <example compact="compact">
3603 <var>old-prerm</var> upgrade <var>new-version</var>
3607 If the script runs but exits with a non-zero
3608 exit status, <prgn>dpkg</prgn> will attempt:
3609 <example compact="compact">
3610 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3612 If this works, the upgrade continues. If this
3613 does not work, the error unwind:
3614 <example compact="compact">
3615 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3617 If this works, then the old-version is
3618 "Installed", if not, the old version is in a
3619 "Failed-Config" state.
3625 If a "conflicting" package is being removed at the same time,
3626 or if any package will be broken (due to <tt>Breaks</tt>):
3629 If <tt>--auto-deconfigure</tt> is
3630 specified, call, for each package to be deconfigured
3631 due to <tt>Breaks</tt>:
3632 <example compact="compact">
3633 <var>deconfigured's-prerm</var> deconfigure \
3634 in-favour <var>package-being-installed</var> <var>version</var>
3637 <example compact="compact">
3638 <var>deconfigured's-postinst</var> abort-deconfigure \
3639 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3641 The deconfigured packages are marked as
3642 requiring configuration, so that if
3643 <tt>--install</tt> is used they will be
3644 configured again if possible.
3647 If any packages depended on a conflicting
3648 package being removed and <tt>--auto-deconfigure</tt> is
3649 specified, call, for each such package:
3650 <example compact="compact">
3651 <var>deconfigured's-prerm</var> deconfigure \
3652 in-favour <var>package-being-installed</var> <var>version</var> \
3653 removing <var>conflicting-package</var> <var>version</var>
3656 <example compact="compact">
3657 <var>deconfigured's-postinst</var> abort-deconfigure \
3658 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3659 removing <var>conflicting-package</var> <var>version</var>
3661 The deconfigured packages are marked as
3662 requiring configuration, so that if
3663 <tt>--install</tt> is used they will be
3664 configured again if possible.
3667 To prepare for removal of each conflicting package, call:
3668 <example compact="compact">
3669 <var>conflictor's-prerm</var> remove \
3670 in-favour <var>package</var> <var>new-version</var>
3673 <example compact="compact">
3674 <var>conflictor's-postinst</var> abort-remove \
3675 in-favour <var>package</var> <var>new-version</var>
3684 If the package is being upgraded, call:
3685 <example compact="compact">
3686 <var>new-preinst</var> upgrade <var>old-version</var>
3688 If this fails, we call:
3690 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3697 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3699 is called. If this works, then the old version
3700 is in an "Installed" state, or else it is left
3701 in an "Unpacked" state.
3706 If it fails, then the old version is left
3707 in an "Half-Installed" state.
3714 Otherwise, if the package had some configuration
3715 files from a previous version installed (i.e., it
3716 is in the "configuration files only" state):
3717 <example compact="compact">
3718 <var>new-preinst</var> install <var>old-version</var>
3722 <var>new-postrm</var> abort-install <var>old-version</var>
3724 If this fails, the package is left in a
3725 "Half-Installed" state, which requires a
3726 reinstall. If it works, the packages is left in
3727 a "Config Files" state.
3730 Otherwise (i.e., the package was completely purged):
3731 <example compact="compact">
3732 <var>new-preinst</var> install
3735 <example compact="compact">
3736 <var>new-postrm</var> abort-install
3738 If the error-unwind fails, the package is in a
3739 "Half Installed" phase, and requires a
3740 reinstall. If the error unwind works, the
3741 package is in a not installed state.
3748 The new package's files are unpacked, overwriting any
3749 that may be on the system already, for example any
3750 from the old version of the same package or from
3751 another package. Backups of the old files are kept
3752 temporarily, and if anything goes wrong the package
3753 management system will attempt to put them back as
3754 part of the error unwind.
3758 It is an error for a package to contain files which
3759 are on the system in another package, unless
3760 <tt>Replaces</tt> is used (see <ref id="replaces">).
3762 The following paragraph is not currently the case:
3763 Currently the <tt>- - force-overwrite</tt> flag is
3764 enabled, downgrading it to a warning, but this may not
3770 It is a more serious error for a package to contain a
3771 plain file or other kind of non-directory where another
3772 package has a directory (again, unless
3773 <tt>Replaces</tt> is used). This error can be
3774 overridden if desired using
3775 <tt>--force-overwrite-dir</tt>, but this is not
3780 Packages which overwrite each other's files produce
3781 behavior which, though deterministic, is hard for the
3782 system administrator to understand. It can easily
3783 lead to "missing" programs if, for example, a package
3784 is installed which overwrites a file from another
3785 package, and is then removed again.<footnote>
3786 Part of the problem is due to what is arguably a
3787 bug in <prgn>dpkg</prgn>.
3792 A directory will never be replaced by a symbolic link
3793 to a directory or vice versa; instead, the existing
3794 state (symlink or not) will be left alone and
3795 <prgn>dpkg</prgn> will follow the symlink if there is
3804 If the package is being upgraded, call
3805 <example compact="compact">
3806 <var>old-postrm</var> upgrade <var>new-version</var>
3810 If this fails, <prgn>dpkg</prgn> will attempt:
3811 <example compact="compact">
3812 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3814 If this works, installation continues. If not,
3816 <example compact="compact">
3817 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3819 If this fails, the old version is left in an
3820 "Half Installed" state. If it works, dpkg now
3822 <example compact="compact">
3823 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3825 If this fails, the old version is left in an
3826 "Half Installed" state. If it works, dpkg now
3828 <example compact="compact">
3829 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3831 If this fails, the old version is in an
3838 This is the point of no return - if
3839 <prgn>dpkg</prgn> gets this far, it won't back off
3840 past this point if an error occurs. This will
3841 leave the package in a fairly bad state, which
3842 will require a successful re-installation to clear
3843 up, but it's when <prgn>dpkg</prgn> starts doing
3844 things that are irreversible.
3849 Any files which were in the old version of the package
3850 but not in the new are removed.
3854 The new file list replaces the old.
3858 The new maintainer scripts replace the old.
3862 Any packages all of whose files have been overwritten
3863 during the installation, and which aren't required for
3864 dependencies, are considered to have been removed.
3865 For each such package
3868 <prgn>dpkg</prgn> calls:
3869 <example compact="compact">
3870 <var>disappearer's-postrm</var> disappear \
3871 <var>overwriter</var> <var>overwriter-version</var>
3875 The package's maintainer scripts are removed.
3878 It is noted in the status database as being in a
3879 sane state, namely not installed (any conffiles
3880 it may have are ignored, rather than being
3881 removed by <prgn>dpkg</prgn>). Note that
3882 disappearing packages do not have their prerm
3883 called, because <prgn>dpkg</prgn> doesn't know
3884 in advance that the package is going to
3891 Any files in the package we're unpacking that are also
3892 listed in the file lists of other packages are removed
3893 from those lists. (This will lobotomize the file list
3894 of the "conflicting" package if there is one.)
3898 The backup files made during installation, above, are
3904 The new package's status is now sane, and recorded as
3909 Here is another point of no return - if the
3910 conflicting package's removal fails we do not unwind
3911 the rest of the installation; the conflicting package
3912 is left in a half-removed limbo.
3917 If there was a conflicting package we go and do the
3918 removal actions (described below), starting with the
3919 removal of the conflicting package's files (any that
3920 are also in the package being installed have already
3921 been removed from the conflicting package's file list,
3922 and so do not get removed now).
3928 <sect id="configdetails"><heading>Details of configuration</heading>
3931 When we configure a package (this happens with <tt>dpkg
3932 --install</tt> and <tt>dpkg --configure</tt>), we first
3933 update any <tt>conffile</tt>s and then call:
3934 <example compact="compact">
3935 <var>postinst</var> configure <var>most-recently-configured-version</var>
3940 No attempt is made to unwind after errors during
3941 configuration. If the configuration fails, the package is in
3942 a "Failed Config" state, and an error message is generated.
3946 If there is no most recently configured version
3947 <prgn>dpkg</prgn> will pass a null argument.
3950 Historical note: Truly ancient (pre-1997) versions of
3951 <prgn>dpkg</prgn> passed <tt><unknown></tt>
3952 (including the angle brackets) in this case. Even older
3953 ones did not pass a second argument at all, under any
3954 circumstance. Note that upgrades using such an old dpkg
3955 version are unlikely to work for other reasons, even if
3956 this old argument behavior is handled by your postinst script.
3962 <sect id="removedetails"><heading>Details of removal and/or
3963 configuration purging</heading>
3969 <example compact="compact">
3970 <var>prerm</var> remove
3974 If prerm fails during replacement due to conflict
3976 <var>conflictor's-postinst</var> abort-remove \
3977 in-favour <var>package</var> <var>new-version</var>
3981 <var>postinst</var> abort-remove
3985 If this fails, the package is in a "Failed-Config"
3986 state, or else it remains "Installed".
3990 The package's files are removed (except <tt>conffile</tt>s).
3993 <example compact="compact">
3994 <var>postrm</var> remove
3998 If it fails, there's no error unwind, and the package is in
3999 an "Half-Installed" state.
4004 All the maintainer scripts except the <prgn>postrm</prgn>
4009 If we aren't purging the package we stop here. Note
4010 that packages which have no <prgn>postrm</prgn> and no
4011 <tt>conffile</tt>s are automatically purged when
4012 removed, as there is no difference except for the
4013 <prgn>dpkg</prgn> status.
4017 The <tt>conffile</tt>s and any backup files
4018 (<tt>~</tt>-files, <tt>#*#</tt> files,
4019 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4024 <example compact="compact">
4025 <var>postrm</var> purge
4029 If this fails, the package remains in a "Config-Files"
4034 The package's file list is removed.
4043 <chapt id="relationships">
4044 <heading>Declaring relationships between packages</heading>
4046 <sect id="depsyntax">
4047 <heading>Syntax of relationship fields</heading>
4050 These fields all have a uniform syntax. They are a list of
4051 package names separated by commas.
4055 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4056 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4057 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4058 control file fields of the package, which declare
4059 dependencies on other packages, the package names listed may
4060 also include lists of alternative package names, separated
4061 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4062 if any one of the alternative packages is installed, that
4063 part of the dependency is considered to be satisfied.
4067 All of the fields except for <tt>Provides</tt> may restrict
4068 their applicability to particular versions of each named
4069 package. This is done in parentheses after each individual
4070 package name; the parentheses should contain a relation from
4071 the list below followed by a version number, in the format
4072 described in <ref id="f-Version">.
4076 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4077 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4078 strictly earlier, earlier or equal, exactly equal, later or
4079 equal and strictly later, respectively. The deprecated
4080 forms <tt><</tt> and <tt>></tt> were used to mean
4081 earlier/later or equal, rather than strictly earlier/later,
4082 so they should not appear in new packages (though
4083 <prgn>dpkg</prgn> still supports them).
4087 Whitespace may appear at any point in the version
4088 specification subject to the rules in <ref
4089 id="controlsyntax">, and must appear where it's necessary to
4090 disambiguate; it is not otherwise significant. All of the
4091 relationship fields may span multiple lines. For
4092 consistency and in case of future changes to
4093 <prgn>dpkg</prgn> it is recommended that a single space be
4094 used after a version relationship and before a version
4095 number; it is also conventional to put a single space after
4096 each comma, on either side of each vertical bar, and before
4097 each open parenthesis. When wrapping a relationship field, it
4098 is conventional to do so after a comma and before the space
4099 following that comma.
4103 For example, a list of dependencies might appear as:
4104 <example compact="compact">
4107 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4112 All fields that specify build-time relationships
4113 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4114 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
4115 may be restricted to a certain set of architectures. This
4116 is indicated in brackets after each individual package name and
4117 the optional version specification. The brackets enclose a
4118 list of Debian architecture names separated by whitespace.
4119 Exclamation marks may be prepended to each of the names.
4120 (It is not permitted for some names to be prepended with
4121 exclamation marks while others aren't.) If the current Debian
4122 host architecture is not in this list and there are no
4123 exclamation marks in the list, or it is in the list with a
4124 prepended exclamation mark, the package name and the
4125 associated version specification are ignored completely for
4126 the purposes of defining the relationships.
4131 <example compact="compact">
4133 Build-Depends-Indep: texinfo
4134 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4135 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4140 Note that the binary package relationship fields such as
4141 <tt>Depends</tt> appear in one of the binary package
4142 sections of the control file, whereas the build-time
4143 relationships such as <tt>Build-Depends</tt> appear in the
4144 source package section of the control file (which is the
4149 <sect id="binarydeps">
4150 <heading>Binary Dependencies - <tt>Depends</tt>,
4151 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4152 <tt>Pre-Depends</tt>
4156 Packages can declare in their control file that they have
4157 certain relationships to other packages - for example, that
4158 they may not be installed at the same time as certain other
4159 packages, and/or that they depend on the presence of others.
4163 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4164 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4165 <tt>Breaks</tt> and <tt>Conflicts</tt> control file fields.
4169 These seven fields are used to declare a dependency
4170 relationship by one package on another. Except for
4171 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4172 depending (binary) package's control file.
4173 (<tt>Enhances</tt> appears in the recommending package's
4174 control file, and <tt>Breaks</tt> appears in the version of
4175 depended-on package which causes the named package to
4180 A <tt>Depends</tt> field takes effect <em>only</em> when a
4181 package is to be configured. It does not prevent a package
4182 being on the system in an unconfigured state while its
4183 dependencies are unsatisfied, and it is possible to replace
4184 a package whose dependencies are satisfied and which is
4185 properly installed with a different version whose
4186 dependencies are not and cannot be satisfied; when this is
4187 done the depending package will be left unconfigured (since
4188 attempts to configure it will give errors) and will not
4189 function properly. If it is necessary, a
4190 <tt>Pre-Depends</tt> field can be used, which has a partial
4191 effect even when a package is being unpacked, as explained
4192 in detail below. (The other three dependency fields,
4193 <tt>Recommends</tt>, <tt>Suggests</tt> and
4194 <tt>Enhances</tt>, are only used by the various front-ends
4195 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4196 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4200 For this reason packages in an installation run are usually
4201 all unpacked first and all configured later; this gives
4202 later versions of packages with dependencies on later
4203 versions of other packages the opportunity to have their
4204 dependencies satisfied.
4208 In case of circular dependencies, since installation or
4209 removal order honoring the dependency order can't be
4210 established, dependency loops are broken at some point
4211 (based on rules below), and some packages may not be able to
4212 rely on their dependencies being present when being
4213 installed or removed, depending on which side of the break
4214 of the circular dependency loop they happen to be on. If one
4215 of the packages in the loop has no postinst script, then the
4216 cycle will be broken at that package, so as to ensure that
4217 all postinst scripts run with the dependencies properly
4218 configured if this is possible. Otherwise the breaking point
4223 The <tt>Depends</tt> field thus allows package maintainers
4224 to impose an order in which packages should be configured.
4228 The meaning of the five dependency fields is as follows:
4230 <tag><tt>Depends</tt></tag>
4233 This declares an absolute dependency. A package will
4234 not be configured unless all of the packages listed in
4235 its <tt>Depends</tt> field have been correctly
4240 The <tt>Depends</tt> field should be used if the
4241 depended-on package is required for the depending
4242 package to provide a significant amount of
4247 The <tt>Depends</tt> field should also be used if the
4248 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4249 <prgn>postrm</prgn> scripts require the package to be
4250 present in order to run. Note, however, that the
4251 <prgn>postrm</prgn> cannot rely on any non-essential
4252 packages to be present during the <tt>purge</tt>
4256 <tag><tt>Recommends</tt></tag>
4259 This declares a strong, but not absolute, dependency.
4263 The <tt>Recommends</tt> field should list packages
4264 that would be found together with this one in all but
4265 unusual installations.
4269 <tag><tt>Suggests</tt></tag>
4271 This is used to declare that one package may be more
4272 useful with one or more others. Using this field
4273 tells the packaging system and the user that the
4274 listed packages are related to this one and can
4275 perhaps enhance its usefulness, but that installing
4276 this one without them is perfectly reasonable.
4279 <tag><tt>Enhances</tt></tag>
4281 This field is similar to Suggests but works in the
4282 opposite direction. It is used to declare that a
4283 package can enhance the functionality of another
4287 <tag><tt>Pre-Depends</tt></tag>
4290 This field is like <tt>Depends</tt>, except that it
4291 also forces <prgn>dpkg</prgn> to complete installation
4292 of the packages named before even starting the
4293 installation of the package which declares the
4294 pre-dependency, as follows:
4298 When a package declaring a pre-dependency is about to
4299 be <em>unpacked</em> the pre-dependency can be
4300 satisfied if the depended-on package is either fully
4301 configured, <em>or even if</em> the depended-on
4302 package(s) are only unpacked or half-configured,
4303 provided that they have been configured correctly at
4304 some point in the past (and not removed or partially
4305 removed since). In this case, both the
4306 previously-configured and currently unpacked or
4307 half-configured versions must satisfy any version
4308 clause in the <tt>Pre-Depends</tt> field.
4312 When the package declaring a pre-dependency is about
4313 to be <em>configured</em>, the pre-dependency will be
4314 treated as a normal <tt>Depends</tt>, that is, it will
4315 be considered satisfied only if the depended-on
4316 package has been correctly configured.
4320 <tt>Pre-Depends</tt> should be used sparingly,
4321 preferably only by packages whose premature upgrade or
4322 installation would hamper the ability of the system to
4323 continue with any upgrade that might be in progress.
4327 <tt>Pre-Depends</tt> are also required if the
4328 <prgn>preinst</prgn> script depends on the named
4329 package. It is best to avoid this situation if
4337 When selecting which level of dependency to use you should
4338 consider how important the depended-on package is to the
4339 functionality of the one declaring the dependency. Some
4340 packages are composed of components of varying degrees of
4341 importance. Such a package should list using
4342 <tt>Depends</tt> the package(s) which are required by the
4343 more important components. The other components'
4344 requirements may be mentioned as Suggestions or
4345 Recommendations, as appropriate to the components' relative
4351 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4354 Using <tt>Breaks</tt> may cause problems for upgrades from older
4355 versions of Debian and should not be used until the stable
4356 release of Debian supports <tt>Breaks</tt>.
4360 When one binary package declares that it breaks another,
4361 <prgn>dpkg</prgn> will refuse to allow the package which
4362 declares <tt>Breaks</tt> be installed unless the broken
4363 package is deconfigured first, and it will refuse to
4364 allow the broken package to be reconfigured.
4368 A package will not be regarded as causing breakage merely
4369 because its configuration files are still installed; it must
4370 be at least half-installed.
4374 A special exception is made for packages which declare that
4375 they break their own package name or a virtual package which
4376 they provide (see below): this does not count as a real
4381 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4382 version clause; such a <tt>Breaks</tt> is introduced in the
4383 version of an (implicit or explicit) dependency which
4384 violates an assumption or reveals a bug in earlier versions
4385 of the broken package. This use of <tt>Breaks</tt> will
4386 inform higher-level package management tools that broken
4387 package must be upgraded before the new one.
4391 If the breaking package also overwrites some files from the
4392 older package, it should use <tt>Replaces</tt> (not
4393 <tt>Conflicts</tt>) to ensure this goes smoothly.
4397 <sect id="conflicts">
4398 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4401 When one binary package declares a conflict with another
4402 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4403 refuse to allow them to be installed on the system at the
4408 If one package is to be installed, the other must be removed
4409 first - if the package being installed is marked as
4410 replacing (see <ref id="replaces">) the one on the system,
4411 or the one on the system is marked as deselected, or both
4412 packages are marked <tt>Essential</tt>, then
4413 <prgn>dpkg</prgn> will automatically remove the package
4414 which is causing the conflict, otherwise it will halt the
4415 installation of the new package with an error. This
4416 mechanism is specifically designed to produce an error when
4417 the installed package is <tt>Essential</tt>, but the new
4422 A package will not cause a conflict merely because its
4423 configuration files are still installed; it must be at least
4428 A special exception is made for packages which declare a
4429 conflict with their own package name, or with a virtual
4430 package which they provide (see below): this does not
4431 prevent their installation, and allows a package to conflict
4432 with others providing a replacement for it. You use this
4433 feature when you want the package in question to be the only
4434 package providing some feature.
4438 A <tt>Conflicts</tt> entry should almost never have an
4439 "earlier than" version clause. This would prevent
4440 <prgn>dpkg</prgn> from upgrading or installing the package
4441 which declared such a conflict until the upgrade or removal
4442 of the conflicted-with package had been completed. Instead,
4443 <tt>Breaks</tt> may be used (once <tt>Breaks</tt> is supported
4444 by the stable release of Debian).
4448 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4452 As well as the names of actual ("concrete") packages, the
4453 package relationship fields <tt>Depends</tt>,
4454 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4455 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4456 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4457 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4458 may mention "virtual packages".
4462 A <em>virtual package</em> is one which appears in the
4463 <tt>Provides</tt> control file field of another package.
4464 The effect is as if the package(s) which provide a
4465 particular virtual package name had been listed by name
4466 everywhere the virtual package name appears. (See also <ref
4471 If there are both concrete and virtual packages of the same
4472 name, then the dependency may be satisfied (or the conflict
4473 caused) by either the concrete package with the name in
4474 question or any other concrete package which provides the
4475 virtual package with the name in question. This is so that,
4476 for example, supposing we have
4477 <example compact="compact">
4480 </example> and someone else releases an enhanced version of
4481 the <tt>bar</tt> package they can say:
4482 <example compact="compact">
4486 and the <tt>bar-plus</tt> package will now also satisfy the
4487 dependency for the <tt>foo</tt> package.
4491 If a relationship field has a version number attached
4492 then only real packages will be considered to see whether
4493 the relationship is satisfied (or the prohibition violated,
4494 for a conflict or breakage) - it is assumed that a real
4495 package which provides the virtual package is not of the
4496 "right" version. So, a <tt>Provides</tt> field may not
4497 contain version numbers, and the version number of the
4498 concrete package which provides a particular virtual package
4499 will not be looked at when considering a dependency on or
4500 conflict with the virtual package name.
4504 It is likely that the ability will be added in a future
4505 release of <prgn>dpkg</prgn> to specify a version number for
4506 each virtual package it provides. This feature is not yet
4507 present, however, and is expected to be used only
4512 If you want to specify which of a set of real packages
4513 should be the default to satisfy a particular dependency on
4514 a virtual package, you should list the real package as an
4515 alternative before the virtual one.
4520 <sect id="replaces"><heading>Overwriting files and replacing
4521 packages - <tt>Replaces</tt></heading>
4524 Packages can declare in their control file that they should
4525 overwrite files in certain other packages, or completely
4526 replace other packages. The <tt>Replaces</tt> control file
4527 field has these two distinct purposes.
4530 <sect1><heading>Overwriting files in other packages</heading>
4533 Firstly, as mentioned before, it is usually an error for a
4534 package to contain files which are on the system in
4539 However, if the overwriting package declares that it
4540 <tt>Replaces</tt> the one containing the file being
4541 overwritten, then <prgn>dpkg</prgn> will replace the file
4542 from the old package with that from the new. The file
4543 will no longer be listed as "owned" by the old package.
4547 If a package is completely replaced in this way, so that
4548 <prgn>dpkg</prgn> does not know of any files it still
4549 contains, it is considered to have "disappeared". It will
4550 be marked as not wanted on the system (selected for
4551 removal) and not installed. Any <tt>conffile</tt>s
4552 details noted for the package will be ignored, as they
4553 will have been taken over by the overwriting package. The
4554 package's <prgn>postrm</prgn> script will be run with a
4555 special argument to allow the package to do any final
4556 cleanup required. See <ref id="mscriptsinstact">.
4559 Replaces is a one way relationship -- you have to
4560 install the replacing package after the replaced
4567 For this usage of <tt>Replaces</tt>, virtual packages (see
4568 <ref id="virtual">) are not considered when looking at a
4569 <tt>Replaces</tt> field - the packages declared as being
4570 replaced must be mentioned by their real names.
4574 Furthermore, this usage of <tt>Replaces</tt> only takes
4575 effect when both packages are at least partially on the
4576 system at once, so that it can only happen if they do not
4577 conflict or if the conflict has been overridden.
4582 <sect1><heading>Replacing whole packages, forcing their
4586 Secondly, <tt>Replaces</tt> allows the packaging system to
4587 resolve which package should be removed when there is a
4588 conflict - see <ref id="conflicts">. This usage only
4589 takes effect when the two packages <em>do</em> conflict,
4590 so that the two usages of this field do not interfere with
4595 In this situation, the package declared as being replaced
4596 can be a virtual package, so for example, all mail
4597 transport agents (MTAs) would have the following fields in
4598 their control files:
4599 <example compact="compact">
4600 Provides: mail-transport-agent
4601 Conflicts: mail-transport-agent
4602 Replaces: mail-transport-agent
4604 ensuring that only one MTA can be installed at any one
4609 <sect id="sourcebinarydeps">
4610 <heading>Relationships between source and binary packages -
4611 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4612 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4616 Source packages that require certain binary packages to be
4617 installed or absent at the time of building the package
4618 can declare relationships to those binary packages.
4622 This is done using the <tt>Build-Depends</tt>,
4623 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4624 <tt>Build-Conflicts-Indep</tt> control file fields.
4628 Build-dependencies on "build-essential" binary packages can be
4629 omitted. Please see <ref id="pkg-relations"> for more information.
4633 The dependencies and conflicts they define must be satisfied
4634 (as defined earlier for binary packages) in order to invoke
4635 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4637 If you make "build-arch" or "binary-arch", you need
4638 Build-Depends. If you make "build-indep" or
4639 "binary-indep", you need Build-Depends and
4640 Build-Depends-Indep. If you make "build" or "binary",
4644 There is no Build-Depends-Arch; this role is essentially
4645 met with Build-Depends. Anyone building the
4646 <tt>build-indep</tt> and binary-indep<tt></tt> targets
4647 is basically assumed to be building the whole package
4648 anyway and so installs all build dependencies. The
4649 autobuilders use <tt>dpkg-buildpackage -B</tt>, which
4650 calls <tt>build</tt> (not <tt>build-arch</tt>, since it
4651 does not yet know how to check for its existence) and
4652 <tt>binary-arch</tt>.
4655 The purpose of the original split, I recall, was so that
4656 the autobuilders wouldn't need to install extra packages
4657 needed only for the binary-indep targets. But without a
4658 build-arch/build-indep split, this didn't work, since
4659 most of the work is done in the build target, not in the
4665 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4667 The <tt>Build-Depends</tt> and
4668 <tt>Build-Conflicts</tt> fields must be satisfied when
4669 any of the following targets is invoked:
4670 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4671 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4672 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4674 <tag><tt>Build-Depends-Indep</tt>,
4675 <tt>Build-Conflicts-Indep</tt></tag>
4677 The <tt>Build-Depends-Indep</tt> and
4678 <tt>Build-Conflicts-Indep</tt> fields must be
4679 satisfied when any of the following targets is
4680 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4681 <tt>binary</tt> and <tt>binary-indep</tt>.
4691 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4694 Packages containing shared libraries must be constructed with
4695 a little care to make sure that the shared library is always
4696 available. This is especially important for packages whose
4697 shared libraries are vitally important, such as the C library
4698 (currently <tt>libc6</tt>).
4702 Packages involving shared libraries should be split up into
4703 several binary packages. This section mostly deals with how
4704 this separation is to be accomplished; rules for files within
4705 the shared library packages are in <ref id="libraries"> instead.
4708 <sect id="sharedlibs-runtime">
4709 <heading>Run-time shared libraries</heading>
4712 The run-time shared library needs to be placed in a package
4713 whose name changes whenever the shared object version
4716 Since it is common place to install several versions of a
4717 package that just provides shared libraries, it is a
4718 good idea that the library package should not
4719 contain any extraneous non-versioned files, unless they
4720 happen to be in versioned directories.</p>
4722 The most common mechanism is to place it in a package
4724 <package><var>libraryname</var><var>soversion</var></package>,
4725 where <file><var>soversion</var></file> is the version number
4726 in the soname of the shared library<footnote>
4727 The soname is the shared object name: it's the thing
4728 that has to match exactly between building an executable
4729 and running it for the dynamic linker to be able run the
4730 program. For example, if the soname of the library is
4731 <file>libfoo.so.6</file>, the library package would be
4732 called <file>libfoo6</file>.
4734 Alternatively, if it would be confusing to directly append
4735 <var>soversion</var> to <var>libraryname</var> (e.g. because
4736 <var>libraryname</var> itself ends in a number), you may use
4737 <package><var>libraryname</var>-<var>soversion</var></package> and
4738 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4743 If you have several shared libraries built from the same
4744 source tree you may lump them all together into a single
4745 shared library package, provided that you change all of
4746 their sonames at once (so that you don't get filename
4747 clashes if you try to install different versions of the
4748 combined shared libraries package).
4752 The package should install the shared libraries under
4753 their normal names. For example, the <package>libgdbm3</package>
4754 package should install <file>libgdbm.so.3.0.0</file> as
4755 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4756 renamed or re-linked by any <prgn>prerm</prgn> or
4757 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4758 of renaming things safely without affecting running programs,
4759 and attempts to interfere with this are likely to lead to
4764 Shared libraries should not be installed executable, since
4765 the dynamic linker does not require this and trying to
4766 execute a shared library usually results in a core dump.
4770 The run-time library package should include the symbolic link that
4771 <prgn>ldconfig</prgn> would create for the shared libraries.
4772 For example, the <package>libgdbm3</package> package should include
4773 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4774 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4775 linker (for example <prgn>ld.so</prgn> or
4776 <prgn>ld-linux.so.*</prgn>) can find the library between the
4777 time that <prgn>dpkg</prgn> installs it and the time that
4778 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4780 The package management system requires the library to be
4781 placed before the symbolic link pointing to it in the
4782 <file>.deb</file> file. This is so that when
4783 <prgn>dpkg</prgn> comes to install the symlink
4784 (overwriting the previous symlink pointing at an older
4785 version of the library), the new shared library is already
4786 in place. In the past, this was achieved by creating the
4787 library in the temporary packaging directory before
4788 creating the symlink. Unfortunately, this was not always
4789 effective, since the building of the tar file in the
4790 <file>.deb</file> depended on the behavior of the underlying
4791 file system. Some file systems (such as reiserfs) reorder
4792 the files so that the order of creation is forgotten.
4793 Since version 1.7.0, <prgn>dpkg</prgn>
4794 reorders the files itself as necessary when building a
4795 package. Thus it is no longer important to concern
4796 oneself with the order of file creation.
4800 <sect1 id="ldconfig">
4801 <heading><tt>ldconfig</tt></heading>
4804 Any package installing shared libraries in one of the default
4805 library directories of the dynamic linker (which are currently
4806 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4807 listed in <file>/etc/ld.so.conf</file><footnote>
4809 <list compact="compact">
4810 <item>/usr/local/lib</item>
4811 <item>/usr/lib/libc5-compat</item>
4812 <item>/lib/libc5-compat</item>
4815 must use <prgn>ldconfig</prgn> to update the shared library
4820 The package maintainer scripts must only call
4821 <prgn>ldconfig</prgn> under these circumstances:
4822 <list compact="compact">
4823 <item>When the <prgn>postinst</prgn> script is run with a
4824 first argument of <tt>configure</tt>, the script must call
4825 <prgn>ldconfig</prgn>, and may optionally invoke
4826 <prgn>ldconfig</prgn> at other times.
4828 <item>When the <prgn>postrm</prgn> script is run with a
4829 first argument of <tt>remove</tt>, the script should call
4830 <prgn>ldconfig</prgn>.
4835 During install or upgrade, the preinst is called before
4836 the new files are installed, so calling "ldconfig" is
4837 pointless. The preinst of an existing package can also be
4838 called if an upgrade fails. However, this happens during
4839 the critical time when a shared libs may exist on-disk
4840 under a temporary name. Thus, it is dangerous and
4841 forbidden by current policy to call "ldconfig" at this
4846 When a package is installed or upgraded, "postinst
4847 configure" runs after the new files are safely on-disk.
4848 Since it is perfectly safe to invoke ldconfig
4849 unconditionally in a postinst, it is OK for a package to
4850 simply put ldconfig in its postinst without checking the
4851 argument. The postinst can also be called to recover from
4852 a failed upgrade. This happens before any new files are
4853 unpacked, so there is no reason to call "ldconfig" at this
4858 For a package that is being removed, prerm is
4859 called with all the files intact, so calling ldconfig is
4860 useless. The other calls to "prerm" happen in the case of
4861 upgrade at a time when all the files of the old package
4862 are on-disk, so again calling "ldconfig" is pointless.
4866 postrm, on the other hand, is called with the "remove"
4867 argument just after the files are removed, so this is
4868 the proper time to call "ldconfig" to notify the system
4869 of the fact that the shared libraries from the package
4870 are removed. The postrm can be called at several other
4871 times. At the time of "postrm purge", "postrm
4872 abort-install", or "postrm abort-upgrade", calling
4873 "ldconfig" is useless because the shared lib files are
4874 not on-disk. However, when "postrm" is invoked with
4875 arguments "upgrade", "failed-upgrade", or "disappear", a
4876 shared lib may exist on-disk under a temporary filename.
4884 <sect id="sharedlibs-support-files">
4885 <heading>Shared library support files</heading>
4888 If your package contains files whose names do not change with
4889 each change in the library shared object version, you must not
4890 put them in the shared library package. Otherwise, several
4891 versions of the shared library cannot be installed at the same
4892 time without filename clashes, making upgrades and transitions
4893 unnecessarily difficult.
4897 It is recommended that supporting files and run-time support
4898 programs that do not need to be invoked manually by users, but
4899 are nevertheless required for the package to function, be placed
4900 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
4901 preferably under <file>/usr/lib/</file><var>package-name</var>.
4902 If the program or file is architecture independent, the
4903 recommendation is for it to be placed in a subdirectory of
4904 <file>/usr/share</file> instead, preferably under
4905 <file>/usr/share/</file><var>package-name</var>. Following the
4906 <var>package-name</var> naming convention ensures that the file
4907 names change when the shared object version changes.
4911 Run-time support programs that use the shared library but are
4912 not required for the library to function or files used by the
4913 shared library that can be used by any version of the shared
4914 library package should instead be put in a separate package.
4915 This package might typically be named
4916 <package><var>libraryname</var>-tools</package>; note the
4917 absence of the <var>soversion</var> in the package name.
4921 Files and support programs only useful when compiling software
4922 against the library should be included in the development
4923 package for the library.<footnote>
4924 For example, a <file><var>package-name</var>-config</file>
4925 script or <package>pkg-config</package> configuration files.
4930 <sect id="sharedlibs-static">
4931 <heading>Static libraries</heading>
4934 The static library (<file><var>libraryname.a</var></file>)
4935 is usually provided in addition to the shared version.
4936 It is placed into the development package (see below).
4940 In some cases, it is acceptable for a library to be
4941 available in static form only; these cases include:
4943 <item>libraries for languages whose shared library support
4944 is immature or unstable</item>
4945 <item>libraries whose interfaces are in flux or under
4946 development (commonly the case when the library's
4947 major version number is zero, or where the ABI breaks
4948 across patchlevels)</item>
4949 <item>libraries which are explicitly intended to be
4950 available only in static form by their upstream
4955 <sect id="sharedlibs-dev">
4956 <heading>Development files</heading>
4959 The development files associated to a shared library need to be
4960 placed in a package called
4961 <package><var>libraryname</var><var>soversion</var>-dev</package>,
4962 or if you prefer only to support one development version at a
4963 time, <package><var>libraryname</var>-dev</package>.
4967 In case several development versions of a library exist, you may
4968 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
4969 <ref id="conflicts">) to ensure that the user only installs one
4970 development version at a time (as different development versions are
4971 likely to have the same header files in them, which would cause a
4972 filename clash if both were installed).
4976 The development package should contain a symlink for the associated
4977 shared library without a version number. For example, the
4978 <package>libgdbm-dev</package> package should include a symlink
4979 from <file>/usr/lib/libgdbm.so</file> to
4980 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
4981 (<prgn>ld</prgn>) when compiling packages, as it will only look for
4982 <file>libgdbm.so</file> when compiling dynamically.
4986 <sect id="sharedlibs-intradeps">
4987 <heading>Dependencies between the packages of the same library</heading>
4990 Typically the development version should have an exact
4991 version dependency on the runtime library, to make sure that
4992 compilation and linking happens correctly. The
4993 <tt>${binary:Version}</tt> substitution variable can be
4994 useful for this purpose.
4996 Previously, <tt>${Source-Version}</tt> was used, but its name
4997 was confusing and it has been deprecated since dpkg 1.13.19.
5002 <sect id="sharedlibs-shlibdeps">
5003 <heading>Dependencies between the library and other packages -
5004 the <tt>shlibs</tt> system</heading>
5007 If a package contains a binary or library which links to a
5008 shared library, we must ensure that when the package is
5009 installed on the system, all of the libraries needed are
5010 also installed. This requirement led to the creation of the
5011 <tt>shlibs</tt> system, which is very simple in its design:
5012 any package which <em>provides</em> a shared library also
5013 provides information on the package dependencies required to
5014 ensure the presence of this library, and any package which
5015 <em>uses</em> a shared library uses this information to
5016 determine the dependencies it requires. The files which
5017 contain the mapping from shared libraries to the necessary
5018 dependency information are called <file>shlibs</file> files.
5022 Thus, when a package is built which contains any shared
5023 libraries, it must provide a <file>shlibs</file> file for other
5024 packages to use, and when a package is built which contains
5025 any shared libraries or compiled binaries, it must run
5026 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5027 on these to determine the libraries used and hence the
5028 dependencies needed by this package.<footnote>
5030 In the past, the shared libraries linked to were
5031 determined by calling <prgn>ldd</prgn>, but now
5032 <prgn>objdump</prgn> is used to do this. The only
5033 change this makes to package building is that
5034 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
5035 libraries, whereas in the past this was unnecessary.
5036 The rest of this footnote explains the advantage that
5041 We say that a binary <tt>foo</tt> <em>directly</em> uses
5042 a library <tt>libbar</tt> if it is explicitly linked
5043 with that library (that is, it uses the flag
5044 <tt>-lbar</tt> during the linking stage). Other
5045 libraries that are needed by <tt>libbar</tt> are linked
5046 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5047 linker will load them automatically when it loads
5048 <tt>libbar</tt>. A package should depend on
5049 the libraries it directly uses, and the dependencies for
5050 those libraries should automatically pull in the other
5055 Unfortunately, the <prgn>ldd</prgn> program shows both
5056 the directly and indirectly used libraries, meaning that
5057 the dependencies determined included both direct and
5058 indirect dependencies. The use of <prgn>objdump</prgn>
5059 avoids this problem by determining only the directly
5064 A good example of where this helps is the following. We
5065 could update <tt>libimlib</tt> with a new version that
5066 supports a new graphics format called dgf (but retaining
5067 the same major version number). If we used the old
5068 <prgn>ldd</prgn> method, every package that uses
5069 <tt>libimlib</tt> would need to be recompiled so it
5070 would also depend on <tt>libdgf</tt> or it wouldn't run
5071 due to missing symbols. However with the new system,
5072 packages using <tt>libimlib</tt> can rely on
5073 <tt>libimlib</tt> itself having the dependency on
5074 <tt>libdgf</tt> and so they would not need rebuilding.
5080 In the following sections, we will first describe where the
5081 various <tt>shlibs</tt> files are to be found, then how to
5082 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5083 file format and how to create them if your package contains a
5088 <heading>The <tt>shlibs</tt> files present on the system</heading>
5091 There are several places where <tt>shlibs</tt> files are
5092 found. The following list gives them in the order in which
5094 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5095 (The first one which gives the required information is used.)
5101 <p><file>debian/shlibs.local</file></p>
5104 This lists overrides for this package. Its use is
5105 described below (see <ref id="shlibslocal">).
5110 <p><file>/etc/dpkg/shlibs.override</file></p>
5113 This lists global overrides. This list is normally
5114 empty. It is maintained by the local system
5120 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5123 When packages are being built, any
5124 <file>debian/shlibs</file> files are copied into the
5125 control file area of the temporary build directory and
5126 given the name <file>shlibs</file>. These files give
5127 details of any shared libraries included in the
5129 An example may help here. Let us say that the
5130 source package <tt>foo</tt> generates two binary
5131 packages, <tt>libfoo2</tt> and
5132 <tt>foo-runtime</tt>. When building the binary
5133 packages, the two packages are created in the
5134 directories <file>debian/libfoo2</file> and
5135 <file>debian/foo-runtime</file> respectively.
5136 (<file>debian/tmp</file> could be used instead of one
5137 of these.) Since <tt>libfoo2</tt> provides the
5138 <tt>libfoo</tt> shared library, it will require a
5139 <tt>shlibs</tt> file, which will be installed in
5140 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
5142 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
5143 when <prgn>dpkg-shlibdeps</prgn> is run on the
5145 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
5147 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5148 determine whether <tt>foo-prog</tt>'s library
5149 dependencies are satisfied by any of the libraries
5150 provided by <tt>libfoo2</tt>. For this reason,
5151 <prgn>dpkg-shlibdeps</prgn> must only be run once
5152 all of the individual binary packages'
5153 <tt>shlibs</tt> files have been installed into the
5160 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5163 These are the <file>shlibs</file> files corresponding to
5164 all of the packages installed on the system, and are
5165 maintained by the relevant package maintainers.
5170 <p><file>/etc/dpkg/shlibs.default</file></p>
5173 This file lists any shared libraries whose packages
5174 have failed to provide correct <file>shlibs</file> files.
5175 It was used when the <file>shlibs</file> setup was first
5176 introduced, but it is now normally empty. It is
5177 maintained by the <tt>dpkg</tt> maintainer.
5185 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5186 <file>shlibs</file> files</heading>
5190 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5191 into your <file>debian/rules</file> file. If your package
5192 contains only compiled binaries and libraries (but no scripts),
5193 you can use a command such as:
5194 <example compact="compact">
5195 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5196 debian/tmp/usr/lib/*
5198 Otherwise, you will need to explicitly list the compiled
5199 binaries and libraries.<footnote>
5200 If you are using <tt>debhelper</tt>, the
5201 <prgn>dh_shlibdeps</prgn> program will do this work for
5202 you. It will also correctly handle multi-binary
5208 This command puts the dependency information into the
5209 <file>debian/substvars</file> file, which is then used by
5210 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5211 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5212 field in the control file for this to work.
5216 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
5217 done. If it does complain you might need to create your own
5218 <file>debian/shlibs.local</file> file, as explained below (see
5219 <ref id="shlibslocal">).
5223 If you have multiple binary packages, you will need to call
5224 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5225 compiled libraries or binaries. In such a case, you will
5226 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5227 utilities to specify a different <file>substvars</file> file.
5231 If you are creating a udeb for use in the Debian Installer, you
5232 will need to specify that <prgn>dpkg-shlibdeps</prgn> should use
5233 the dependency line of type <tt>udeb</tt> by adding
5234 <tt>-tudeb</tt> as option<footnote>
5235 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5236 will automatically add this option if it knows it is
5238 </footnote>. If there is no dependency line of type <tt>udeb</tt>
5239 in the <file>shlibs</file> file, <prgn>dpkg-shlibdeps</prgn> will
5240 fall back to the regular dependency line.
5244 For more details on dpkg-shlibdeps, please see
5245 <ref id="pkg-dpkg-shlibdeps"> and
5246 <manref name="dpkg-shlibdeps" section="1">.
5251 <heading>The <file>shlibs</file> File Format</heading>
5254 Each <file>shlibs</file> file has the same format. Lines
5255 beginning with <tt>#</tt> are considered to be comments and
5256 are ignored. Each line is of the form:
5257 <example compact="compact">
5258 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5263 We will explain this by reference to the example of the
5264 <tt>zlib1g</tt> package, which (at the time of writing)
5265 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5269 <var>type</var> is an optional element that indicates the type
5270 of package for which the line is valid. The only type currently
5271 in use is <tt>udeb</tt>. The colon and space after the type are
5276 <var>library-name</var> is the name of the shared library,
5277 in this case <tt>libz</tt>. (This must match the name part
5278 of the soname, see below.)
5282 <var>soname-version</var> is the version part of the soname of
5283 the library. The soname is the thing that must exactly match
5284 for the library to be recognized by the dynamic linker, and is
5286 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5287 example, <tt>libz.so.1</tt>.<footnote>
5288 This can be determined using the command
5289 <example compact="compact">
5290 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5293 The version part is the part which comes after
5294 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
5298 <var>dependencies</var> has the same syntax as a dependency
5299 field in a binary package control file. It should give
5300 details of which packages are required to satisfy a binary
5301 built against the version of the library contained in the
5302 package. See <ref id="depsyntax"> for details.
5306 In our example, if the first version of the <tt>zlib1g</tt>
5307 package which contained a minor number of at least
5308 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5309 <tt>shlibs</tt> entry for this library could say:
5310 <example compact="compact">
5311 libz 1 zlib1g (>= 1:1.1.3)
5313 The version-specific dependency is to avoid warnings from
5314 the dynamic linker about using older shared libraries with
5319 As zlib1g also provides a udeb containing the shared library,
5320 there would also be a second line:
5321 <example compact="compact">
5322 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5328 <heading>Providing a <file>shlibs</file> file</heading>
5331 If your package provides a shared library, you need to create
5332 a <file>shlibs</file> file following the format described above.
5333 It is usual to call this file <file>debian/shlibs</file> (but if
5334 you have multiple binary packages, you might want to call it
5335 <file>debian/shlibs.<var>package</var></file> instead). Then
5336 let <file>debian/rules</file> install it in the control area:
5337 <example compact="compact">
5338 install -m644 debian/shlibs debian/tmp/DEBIAN
5340 or, in the case of a multi-binary package:
5341 <example compact="compact">
5342 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5344 An alternative way of doing this is to create the
5345 <file>shlibs</file> file in the control area directly from
5346 <file>debian/rules</file> without using a <file>debian/shlibs</file>
5347 file at all,<footnote>
5348 This is what <prgn>dh_makeshlibs</prgn> in the
5349 <tt>debhelper</tt> suite does. If your package also has a udeb
5350 that provides a shared library, <prgn>dh_makeshlibs</prgn> can
5351 automatically generate the <tt>udeb:</tt> lines if you specify
5352 the name of the udeb with the <tt>--add-udeb</tt> option.
5354 since the <file>debian/shlibs</file> file itself is ignored by
5355 <prgn>dpkg-shlibdeps</prgn>.
5359 As <prgn>dpkg-shlibdeps</prgn> reads the
5360 <file>DEBIAN/shlibs</file> files in all of the binary packages
5361 being built from this source package, all of the
5362 <file>DEBIAN/shlibs</file> files should be installed before
5363 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5368 <sect1 id="shlibslocal">
5369 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
5372 This file is intended only as a <em>temporary</em> fix if
5373 your binaries or libraries depend on a library whose package
5374 does not yet provide a correct <file>shlibs</file> file.
5378 We will assume that you are trying to package a binary
5379 <tt>foo</tt>. When you try running
5380 <prgn>dpkg-shlibdeps</prgn> you get the following error
5381 message (<tt>-O</tt> displays the dependency information on
5382 <tt>stdout</tt> instead of writing it to
5383 <tt>debian/substvars</tt>, and the lines have been wrapped
5384 for ease of reading):
5385 <example compact="compact">
5386 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
5387 dpkg-shlibdeps: warning: unable to find dependency
5388 information for shared library libbar (soname 1,
5389 path /usr/lib/libbar.so.1, dependency field Depends)
5390 shlibs:Depends=libc6 (>= 2.2.2-2)
5392 You can then run <prgn>ldd</prgn> on the binary to find the
5393 full location of the library concerned:
5394 <example compact="compact">
5396 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5397 libc.so.6 => /lib/libc.so.6 (0x40032000)
5398 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5400 So the <prgn>foo</prgn> binary depends on the
5401 <prgn>libbar</prgn> shared library, but no package seems to
5402 provide a <file>*.shlibs</file> file handling
5403 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5404 determine the package responsible:
5405 <example compact="compact">
5406 $ dpkg -S /usr/lib/libbar.so.1
5407 bar1: /usr/lib/libbar.so.1
5408 $ dpkg -s bar1 | grep Version
5411 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5412 is the one we are using. Now we can file a bug against the
5413 <tt>bar1</tt> package and create our own
5414 <file>debian/shlibs.local</file> to locally fix the problem.
5415 Including the following line into your
5416 <file>debian/shlibs.local</file> file:
5417 <example compact="compact">
5418 libbar 1 bar1 (>= 1.0-1)
5420 should allow the package build to work.
5424 As soon as the maintainer of <tt>bar1</tt> provides a
5425 correct <file>shlibs</file> file, you should remove this line
5426 from your <file>debian/shlibs.local</file> file. (You should
5427 probably also then have a versioned <tt>Build-Depends</tt>
5428 on <tt>bar1</tt> to help ensure that others do not have the
5429 same problem building your package.)
5438 <chapt id="opersys"><heading>The Operating System</heading>
5441 <heading>File system hierarchy</heading>
5445 <heading>File system Structure</heading>
5448 The location of all installed files and directories must
5449 comply with the File system Hierarchy Standard (FHS),
5450 version 2.3, with the exceptions noted below, and except
5451 where doing so would violate other terms of Debian
5452 Policy. The following exceptions to the FHS apply:
5457 Legacy XFree86 servers are permitted to retain the
5458 configuration file location
5459 <file>/etc/X11/XF86Config-4</file>.
5464 The optional rules related to user specific
5465 configuration files for applications are stored in
5466 the user's home directory are relaxed. It is
5467 recommended that such files start with the
5468 '<tt>.</tt>' character (a "dot file"), and if an
5469 application needs to create more than one dot file
5470 then the preferred placement is in a subdirectory
5471 with a name starting with a '.' character, (a "dot
5472 directory"). In this case it is recommended the
5473 configuration files not start with the '.'
5479 The requirement for amd64 to use <file>/lib64</file>
5480 for 64 bit binaries is removed.
5485 The requirement that
5486 <file>/usr/local/share/man</file> be "synonymous"
5487 with <file>/usr/local/man</file> is relaxed to a
5492 The requirement that windowmanagers with a single
5493 configuration file call it <file>system.*wmrc</file>
5494 is removed, as is the restriction that the window
5495 manager subdirectory be named identically to the
5496 window manager name itself.
5501 The requirement that boot manager configuration
5502 files live in <file>/etc</file>, or at least are
5503 symlinked there, is relaxed to a recommendation.
5510 The version of this document referred here can be
5511 found in the <tt>debian-policy</tt> package or on <url
5512 id="http://www.debian.org/doc/packaging-manuals/fhs/"
5513 name="FHS (Debian copy)"> alongside this manual (or, if
5514 you have the <package>debian-policy</package> installed,
5516 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5517 (local copy)">). The
5518 latest version, which may be a more recent version, may
5520 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5521 Specific questions about following the standard may be
5522 asked on the <tt>debian-devel</tt> mailing list, or
5523 referred to the FHS mailing list (see the
5524 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5530 <heading>Site-specific programs</heading>
5533 As mandated by the FHS, packages must not place any
5534 files in <file>/usr/local</file>, either by putting them in
5535 the file system archive to be unpacked by <prgn>dpkg</prgn>
5536 or by manipulating them in their maintainer scripts.
5540 However, the package may create empty directories below
5541 <file>/usr/local</file> so that the system administrator knows
5542 where to place site-specific files. These are not
5543 directories <em>in</em> <file>/usr/local</file>, but are
5544 children of directories in <file>/usr/local</file>. These
5545 directories (<file>/usr/local/*/dir/</file>)
5546 should be removed on package removal if they are
5551 Note, that this applies only to directories <em>below</em>
5552 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
5553 Packages must not create sub-directories in the directory
5554 <file>/usr/local</file> itself, except those listed in FHS,
5555 section 4.5. However, you may create directories below
5556 them as you wish. You must not remove any of the
5557 directories listed in 4.5, even if you created them.
5561 Since <file>/usr/local</file> can be mounted read-only from a
5562 remote server, these directories must be created and
5563 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5564 maintainer scripts and not be included in the
5565 <file>.deb</file> archive. These scripts must not fail if
5566 either of these operations fail.
5570 For example, the <tt>emacsen-common</tt> package could
5571 contain something like
5572 <example compact="compact">
5573 if [ ! -e /usr/local/share/emacs ]
5575 if mkdir /usr/local/share/emacs 2>/dev/null
5577 chown root:staff /usr/local/share/emacs
5578 chmod 2775 /usr/local/share/emacs
5582 in its <prgn>postinst</prgn> script, and
5583 <example compact="compact">
5584 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5585 rmdir /usr/local/share/emacs 2>/dev/null || true
5587 in the <prgn>prerm</prgn> script. (Note that this form is
5588 used to ensure that if the script is interrupted, the
5589 directory <file>/usr/local/share/emacs</file> will still be
5594 If you do create a directory in <file>/usr/local</file> for
5595 local additions to a package, you should ensure that
5596 settings in <file>/usr/local</file> take precedence over the
5597 equivalents in <file>/usr</file>.
5601 However, because <file>/usr/local</file> and its contents are
5602 for exclusive use of the local administrator, a package
5603 must not rely on the presence or absence of files or
5604 directories in <file>/usr/local</file> for normal operation.
5608 The <file>/usr/local</file> directory itself and all the
5609 subdirectories created by the package should (by default) have
5610 permissions 2775 (group-writable and set-group-id) and be
5611 owned by <tt>root:staff</tt>.
5616 <heading>The system-wide mail directory</heading>
5618 The system-wide mail directory is <file>/var/mail</file>. This
5619 directory is part of the base system and should not owned
5620 by any particular mail agents. The use of the old
5621 location <file>/var/spool/mail</file> is deprecated, even
5622 though the spool may still be physically located there.
5623 To maintain partial upgrade compatibility for systems
5624 which have <file>/var/spool/mail</file> as their physical mail
5625 spool, packages using <file>/var/mail</file> must depend on
5626 either <package>libc6</package> (>= 2.1.3-13), or on
5627 <package>base-files</package> (>= 2.2.0), or on later
5628 versions of either one of these packages.
5634 <heading>Users and groups</heading>
5637 <heading>Introduction</heading>
5639 The Debian system can be configured to use either plain or
5644 Some user ids (UIDs) and group ids (GIDs) are reserved
5645 globally for use by certain packages. Because some
5646 packages need to include files which are owned by these
5647 users or groups, or need the ids compiled into binaries,
5648 these ids must be used on any Debian system only for the
5649 purpose for which they are allocated. This is a serious
5650 restriction, and we should avoid getting in the way of
5651 local administration policies. In particular, many sites
5652 allocate users and/or local system groups starting at 100.
5656 Apart from this we should have dynamically allocated ids,
5657 which should by default be arranged in some sensible
5658 order, but the behavior should be configurable.
5662 Packages other than <tt>base-passwd</tt> must not modify
5663 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5664 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5669 <heading>UID and GID classes</heading>
5671 The UID and GID numbers are divided into classes as
5677 Globally allocated by the Debian project, the same
5678 on every Debian system. These ids will appear in
5679 the <file>passwd</file> and <file>group</file> files of all
5680 Debian systems, new ids in this range being added
5681 automatically as the <tt>base-passwd</tt> package is
5686 Packages which need a single statically allocated
5687 uid or gid should use one of these; their
5688 maintainers should ask the <tt>base-passwd</tt>
5696 Dynamically allocated system users and groups.
5697 Packages which need a user or group, but can have
5698 this user or group allocated dynamically and
5699 differently on each system, should use <tt>adduser
5700 --system</tt> to create the group and/or user.
5701 <prgn>adduser</prgn> will check for the existence of
5702 the user or group, and if necessary choose an unused
5703 id based on the ranges specified in
5704 <file>adduser.conf</file>.
5708 <tag>1000-29999:</tag>
5711 Dynamically allocated user accounts. By default
5712 <prgn>adduser</prgn> will choose UIDs and GIDs for
5713 user accounts in this range, though
5714 <file>adduser.conf</file> may be used to modify this
5719 <tag>30000-59999:</tag>
5724 <tag>60000-64999:</tag>
5727 Globally allocated by the Debian project, but only
5728 created on demand. The ids are allocated centrally
5729 and statically, but the actual accounts are only
5730 created on users' systems on demand.
5734 These ids are for packages which are obscure or
5735 which require many statically-allocated ids. These
5736 packages should check for and create the accounts in
5737 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5738 <prgn>adduser</prgn> if it has this facility) if
5739 necessary. Packages which are likely to require
5740 further allocations should have a "hole" left after
5741 them in the allocation, to give them room to
5746 <tag>65000-65533:</tag>
5754 User <tt>nobody</tt>. The corresponding gid refers
5755 to the group <tt>nogroup</tt>.
5762 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5763 not</em> be used, because it is the error return
5772 <sect id="sysvinit">
5773 <heading>System run levels and <file>init.d</file> scripts</heading>
5775 <sect1 id="/etc/init.d">
5776 <heading>Introduction</heading>
5779 The <file>/etc/init.d</file> directory contains the scripts
5780 executed by <prgn>init</prgn> at boot time and when the
5781 init state (or "runlevel") is changed (see <manref
5782 name="init" section="8">).
5786 There are at least two different, yet functionally
5787 equivalent, ways of handling these scripts. For the sake
5788 of simplicity, this document describes only the symbolic
5789 link method. However, it must not be assumed by maintainer
5790 scripts that this method is being used, and any automated
5791 manipulation of the various runlevel behaviors by
5792 maintainer scripts must be performed using
5793 <prgn>update-rc.d</prgn> as described below and not by
5794 manually installing or removing symlinks. For information
5795 on the implementation details of the other method,
5796 implemented in the <tt>file-rc</tt> package, please refer
5797 to the documentation of that package.
5801 These scripts are referenced by symbolic links in the
5802 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5803 runlevels, <prgn>init</prgn> looks in the directory
5804 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5805 execute, where <tt><var>n</var></tt> is the runlevel that
5806 is being changed to, or <tt>S</tt> for the boot-up
5811 The names of the links all have the form
5812 <file>S<var>mm</var><var>script</var></file> or
5813 <file>K<var>mm</var><var>script</var></file> where
5814 <var>mm</var> is a two-digit number and <var>script</var>
5815 is the name of the script (this should be the same as the
5816 name of the actual script in <file>/etc/init.d</file>).
5820 When <prgn>init</prgn> changes runlevel first the targets
5821 of the links whose names start with a <tt>K</tt> are
5822 executed, each with the single argument <tt>stop</tt>,
5823 followed by the scripts prefixed with an <tt>S</tt>, each
5824 with the single argument <tt>start</tt>. (The links are
5825 those in the <file>/etc/rc<var>n</var>.d</file> directory
5826 corresponding to the new runlevel.) The <tt>K</tt> links
5827 are responsible for killing services and the <tt>S</tt>
5828 link for starting services upon entering the runlevel.
5832 For example, if we are changing from runlevel 2 to
5833 runlevel 3, init will first execute all of the <tt>K</tt>
5834 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
5835 all of the <tt>S</tt> prefixed scripts in that directory.
5836 The links starting with <tt>K</tt> will cause the
5837 referred-to file to be executed with an argument of
5838 <tt>stop</tt>, and the <tt>S</tt> links with an argument
5843 The two-digit number <var>mm</var> is used to determine
5844 the order in which to run the scripts: low-numbered links
5845 have their scripts run first. For example, the
5846 <tt>K20</tt> scripts will be executed before the
5847 <tt>K30</tt> scripts. This is used when a certain service
5848 must be started before another. For example, the name
5849 server <prgn>bind</prgn> might need to be started before
5850 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
5851 can set up its access lists. In this case, the script
5852 that starts <prgn>bind</prgn> would have a lower number
5853 than the script that starts <prgn>inn</prgn> so that it
5855 <example compact="compact">
5862 The two runlevels 0 (halt) and 6 (reboot) are slightly
5863 different. In these runlevels, the links with an
5864 <tt>S</tt> prefix are still called after those with a
5865 <tt>K</tt> prefix, but they too are called with the single
5866 argument <tt>stop</tt>.
5870 Also, if the script name ends in <tt>.sh</tt>, the script
5871 will be sourced in runlevel <tt>S</tt> rather than being
5872 run in a forked subprocess, but will be explicitly run by
5873 <prgn>sh</prgn> in all other runlevels.
5878 <heading>Writing the scripts</heading>
5881 Packages that include daemons for system services should
5882 place scripts in <file>/etc/init.d</file> to start or stop
5883 services at boot time or during a change of runlevel.
5884 These scripts should be named
5885 <file>/etc/init.d/<var>package</var></file>, and they should
5886 accept one argument, saying what to do:
5889 <tag><tt>start</tt></tag>
5890 <item>start the service,</item>
5892 <tag><tt>stop</tt></tag>
5893 <item>stop the service,</item>
5895 <tag><tt>restart</tt></tag>
5896 <item>stop and restart the service if it's already running,
5897 otherwise start the service</item>
5899 <tag><tt>reload</tt></tag>
5900 <item><p>cause the configuration of the service to be
5901 reloaded without actually stopping and restarting
5904 <tag><tt>force-reload</tt></tag>
5905 <item>cause the configuration to be reloaded if the
5906 service supports this, otherwise restart the
5910 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
5911 <tt>force-reload</tt> options should be supported by all
5912 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
5917 The <file>init.d</file> scripts must ensure that they will
5918 behave sensibly (i.e., returning success and not starting
5919 multiple copies of a service) if invoked with <tt>start</tt>
5920 when the service is already running, or with <tt>stop</tt>
5921 when it isn't, and that they don't kill unfortunately-named
5922 user processes. The best way to achieve this is usually to
5923 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
5928 If a service reloads its configuration automatically (as
5929 in the case of <prgn>cron</prgn>, for example), the
5930 <tt>reload</tt> option of the <file>init.d</file> script
5931 should behave as if the configuration has been reloaded
5936 The <file>/etc/init.d</file> scripts must be treated as
5937 configuration files, either (if they are present in the
5938 package, that is, in the .deb file) by marking them as
5939 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
5940 by managing them correctly in the maintainer scripts (see
5941 <ref id="config-files">). This is important since we want
5942 to give the local system administrator the chance to adapt
5943 the scripts to the local system, e.g., to disable a
5944 service without de-installing the package, or to specify
5945 some special command line options when starting a service,
5946 while making sure their changes aren't lost during the next
5951 These scripts should not fail obscurely when the
5952 configuration files remain but the package has been
5953 removed, as configuration files remain on the system after
5954 the package has been removed. Only when <prgn>dpkg</prgn>
5955 is executed with the <tt>--purge</tt> option will
5956 configuration files be removed. In particular, as the
5957 <file>/etc/init.d/<var>package</var></file> script itself is
5958 usually a <tt>conffile</tt>, it will remain on the system
5959 if the package is removed but not purged. Therefore, you
5960 should include a <tt>test</tt> statement at the top of the
5962 <example compact="compact">
5963 test -f <var>program-executed-later-in-script</var> || exit 0
5968 Often there are some variables in the <file>init.d</file>
5969 scripts whose values control the behavior of the scripts,
5970 and which a system administrator is likely to want to
5971 change. As the scripts themselves are frequently
5972 <tt>conffile</tt>s, modifying them requires that the
5973 administrator merge in their changes each time the package
5974 is upgraded and the <tt>conffile</tt> changes. To ease
5975 the burden on the system administrator, such configurable
5976 values should not be placed directly in the script.
5977 Instead, they should be placed in a file in
5978 <file>/etc/default</file>, which typically will have the same
5979 base name as the <file>init.d</file> script. This extra file
5980 should be sourced by the script when the script runs. It
5981 must contain only variable settings and comments in SUSv3
5982 <prgn>sh</prgn> format. It may either be a
5983 <tt>conffile</tt> or a configuration file maintained by
5984 the package maintainer scripts. See <ref id="config-files">
5989 To ensure that vital configurable values are always
5990 available, the <file>init.d</file> script should set default
5991 values for each of the shell variables it uses, either
5992 before sourcing the <file>/etc/default/</file> file or
5993 afterwards using something like the <tt>:
5994 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
5995 script must behave sensibly and not fail if the
5996 <file>/etc/default</file> file is deleted.
6001 <heading>Interfacing with the initscript system</heading>
6004 Maintainers should use the abstraction layer provided by
6005 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6006 programs to deal with initscripts in their packages'
6007 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6008 and <prgn>postrm</prgn>.
6012 Directly managing the /etc/rc?.d links and directly
6013 invoking the <file>/etc/init.d/</file> initscripts should
6014 be done only by packages providing the initscript
6015 subsystem (such as <prgn>sysv-rc</prgn> and
6016 <prgn>file-rc</prgn>).
6020 <heading>Managing the links</heading>
6023 The program <prgn>update-rc.d</prgn> is provided for
6024 package maintainers to arrange for the proper creation and
6025 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6026 or their functional equivalent if another method is being
6027 used. This may be used by maintainers in their packages'
6028 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6032 You must not include any <file>/etc/rc<var>n</var>.d</file>
6033 symbolic links in the actual archive or manually create or
6034 remove the symbolic links in maintainer scripts; you must
6035 use the <prgn>update-rc.d</prgn> program instead. (The
6036 former will fail if an alternative method of maintaining
6037 runlevel information is being used.) You must not include
6038 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6039 in the archive either. (Only the <tt>sysvinit</tt>
6044 By default <prgn>update-rc.d</prgn> will start services in
6045 each of the multi-user state runlevels (2, 3, 4, and 5)
6046 and stop them in the halt runlevel (0), the single-user
6047 runlevel (1) and the reboot runlevel (6). The system
6048 administrator will have the opportunity to customize
6049 runlevels by simply adding, moving, or removing the
6050 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6051 symbolic links are being used, or by modifying
6052 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6057 To get the default behavior for your package, put in your
6058 <prgn>postinst</prgn> script
6059 <example compact="compact">
6060 update-rc.d <var>package</var> defaults
6062 and in your <prgn>postrm</prgn>
6063 <example compact="compact">
6064 if [ "$1" = purge ]; then
6065 update-rc.d <var>package</var> remove
6067 </example>. Note that if your package changes runlevels
6068 or priority, you may have to remove and recreate the links,
6069 since otherwise the old links may persist. Refer to the
6070 documentation of <prgn>update-rc.d</prgn>.
6074 This will use a default sequence number of 20. If it does
6075 not matter when or in which order the <file>init.d</file>
6076 script is run, use this default. If it does, then you
6077 should talk to the maintainer of the <prgn>sysvinit</prgn>
6078 package or post to <tt>debian-devel</tt>, and they will
6079 help you choose a number.
6083 For more information about using <tt>update-rc.d</tt>,
6084 please consult its man page <manref name="update-rc.d"
6090 <heading>Running initscripts</heading>
6092 The program <prgn>invoke-rc.d</prgn> is provided to make
6093 it easier for package maintainers to properly invoke an
6094 initscript, obeying runlevel and other locally-defined
6095 constraints that might limit a package's right to start,
6096 stop and otherwise manage services. This program may be
6097 used by maintainers in their packages' scripts.
6101 The package maintainer scripts must use
6102 <prgn>invoke-rc.d</prgn> to invoke the
6103 <file>/etc/init.d/*</file> initscripts, instead of
6104 calling them directly.
6108 By default, <prgn>invoke-rc.d</prgn> will pass any
6109 action requests (start, stop, reload, restart...) to the
6110 <file>/etc/init.d</file> script, filtering out requests
6111 to start or restart a service out of its intended
6116 Most packages will simply need to change:
6117 <example compact="compact">/etc/init.d/<package>
6118 <action></example> in their <prgn>postinst</prgn>
6119 and <prgn>prerm</prgn> scripts to:
6120 <example compact="compact">
6121 if which invoke-rc.d >/dev/null 2>&1; then
6122 invoke-rc.d <var>package</var> <action>
6124 /etc/init.d/<var>package</var> <action>
6130 A package should register its initscript services using
6131 <prgn>update-rc.d</prgn> before it tries to invoke them
6132 using <prgn>invoke-rc.d</prgn>. Invocation of
6133 unregistered services may fail.
6137 For more information about using
6138 <prgn>invoke-rc.d</prgn>, please consult its man page
6139 <manref name="invoke-rc.d" section="8">.
6145 <heading>Boot-time initialization</heading>
6148 There used to be another directory, <file>/etc/rc.boot</file>,
6149 which contained scripts which were run once per machine
6150 boot. This has been deprecated in favour of links from
6151 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6152 described in <ref id="/etc/init.d">. Packages must not
6153 place files in <file>/etc/rc.boot</file>.
6158 <heading>Example</heading>
6161 An example on which you can base your
6162 <file>/etc/init.d</file> scripts is found in
6163 <file>/etc/init.d/skeleton</file>.
6170 <heading>Console messages from <file>init.d</file> scripts</heading>
6173 This section describes the formats to be used for messages
6174 written to standard output by the <file>/etc/init.d</file>
6175 scripts. The intent is to improve the consistency of
6176 Debian's startup and shutdown look and feel. For this
6177 reason, please look very carefully at the details. We want
6178 the messages to have the same format in terms of wording,
6179 spaces, punctuation and case of letters.
6183 Here is a list of overall rules that should be used for
6184 messages generated by <file>/etc/init.d</file> scripts.
6190 The message should fit in one line (fewer than 80
6191 characters), start with a capital letter and end with
6192 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6196 If the script is performing some time consuming task in
6197 the background (not merely starting or stopping a
6198 program, for instance), an ellipsis (three dots:
6199 <tt>...</tt>) should be output to the screen, with no
6200 leading or tailing whitespace or line feeds.
6204 The messages should appear as if the computer is telling
6205 the user what it is doing (politely :-), but should not
6206 mention "it" directly. For example, instead of:
6207 <example compact="compact">
6208 I'm starting network daemons: nfsd mountd.
6210 the message should say
6211 <example compact="compact">
6212 Starting network daemons: nfsd mountd.
6219 <tt>init.d</tt> script should use the following standard
6220 message formats for the situations enumerated below.
6226 <p>When daemons are started</p>
6229 If the script starts one or more daemons, the output
6230 should look like this (a single line, no leading
6232 <example compact="compact">
6233 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6235 The <var>description</var> should describe the
6236 subsystem the daemon or set of daemons are part of,
6237 while <var>daemon-1</var> up to <var>daemon-n</var>
6238 denote each daemon's name (typically the file name of
6243 For example, the output of <file>/etc/init.d/lpd</file>
6245 <example compact="compact">
6246 Starting printer spooler: lpd.
6251 This can be achieved by saying
6252 <example compact="compact">
6253 echo -n "Starting printer spooler: lpd"
6254 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6257 in the script. If there are more than one daemon to
6258 start, the output should look like this:
6259 <example compact="compact">
6260 echo -n "Starting remote file system services:"
6261 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6262 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6263 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6266 This makes it possible for the user to see what is
6267 happening and when the final daemon has been started.
6268 Care should be taken in the placement of white spaces:
6269 in the example above the system administrators can
6270 easily comment out a line if they don't want to start
6271 a specific daemon, while the displayed message still
6277 <p>When a system parameter is being set</p>
6280 If you have to set up different system parameters
6281 during the system boot, you should use this format:
6282 <example compact="compact">
6283 Setting <var>parameter</var> to "<var>value</var>".
6288 You can use a statement such as the following to get
6290 <example compact="compact">
6291 echo "Setting DNS domainname to \"$domainname\"."
6296 Note that the same symbol (<tt>"</tt>) is used for the left
6297 and right quotation marks. A grave accent (<tt>`</tt>) is
6298 not a quote character; neither is an apostrophe
6304 <p>When a daemon is stopped or restarted</p>
6307 When you stop or restart a daemon, you should issue a
6308 message identical to the startup message, except that
6309 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6310 or <tt>Restarting</tt> respectively.
6314 For example, stopping the printer daemon will look like
6316 <example compact="compact">
6317 Stopping printer spooler: lpd.
6323 <p>When something is executed</p>
6326 There are several examples where you have to run a
6327 program at system startup or shutdown to perform a
6328 specific task, for example, setting the system's clock
6329 using <prgn>netdate</prgn> or killing all processes
6330 when the system shuts down. Your message should look
6332 <example compact="compact">
6333 Doing something very useful...done.
6335 You should print the <tt>done.</tt> immediately after
6336 the job has been completed, so that the user is
6337 informed why they have to wait. You can get this
6339 <example compact="compact">
6340 echo -n "Doing something very useful..."
6349 <p>When the configuration is reloaded</p>
6352 When a daemon is forced to reload its configuration
6353 files you should use the following format:
6354 <example compact="compact">
6355 Reloading <var>description</var> configuration...done.
6357 where <var>description</var> is the same as in the
6358 daemon starting message.
6366 <heading>Cron jobs</heading>
6369 Packages must not modify the configuration file
6370 <file>/etc/crontab</file>, and they must not modify the files in
6371 <file>/var/spool/cron/crontabs</file>.</p>
6374 If a package wants to install a job that has to be executed
6375 via cron, it should place a file with the name of the
6376 package in one or more of the following directories:
6377 <example compact="compact">
6383 As these directory names imply, the files within them are
6384 executed on an hourly, daily, weekly, or monthly basis,
6385 respectively. The exact times are listed in
6386 <file>/etc/crontab</file>.</p>
6389 All files installed in any of these directories must be
6390 scripts (e.g., shell scripts or Perl scripts) so that they
6391 can easily be modified by the local system administrator.
6392 In addition, they must be treated as configuration files.
6396 If a certain job has to be executed at some other frequency or
6397 at a specific time, the package should install a file
6398 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6399 same syntax as <file>/etc/crontab</file> and is processed by
6400 <prgn>cron</prgn> automatically. The file must also be
6401 treated as a configuration file. (Note that entries in the
6402 <file>/etc/cron.d</file> directory are not handled by
6403 <prgn>anacron</prgn>. Thus, you should only use this
6404 directory for jobs which may be skipped if the system is not
6408 The scripts or crontab entries in these directories should
6409 check if all necessary programs are installed before they
6410 try to execute them. Otherwise, problems will arise when a
6411 package was removed but not purged since configuration files
6412 are kept on the system in this situation.</p>
6416 <heading>Menus</heading>
6419 The Debian <tt>menu</tt> package provides a standard
6420 interface between packages providing applications and
6421 <em>menu programs</em> (either X window managers or
6422 text-based menu programs such as <prgn>pdmenu</prgn>).
6426 All packages that provide applications that need not be
6427 passed any special command line arguments for normal
6428 operation should register a menu entry for those
6429 applications, so that users of the <tt>menu</tt> package
6430 will automatically get menu entries in their window
6431 managers, as well in shells like <tt>pdmenu</tt>.
6435 Menu entries should follow the current menu policy.
6439 The menu policy can be found in the <tt>menu-policy</tt>
6440 files in the <tt>debian-policy</tt> package.
6441 It is also available from the Debian web mirrors at
6442 <tt><url name="/doc/packaging-manuals/menu-policy/"
6443 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6447 Please also refer to the <em>Debian Menu System</em>
6448 documentation that comes with the <package>menu</package>
6449 package for information about how to register your
6455 <heading>Multimedia handlers</heading>
6458 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6459 is a mechanism for encoding files and data streams and
6460 providing meta-information about them, in particular their
6461 type (e.g. audio or video) and format (e.g. PNG, HTML,
6466 Registration of MIME type handlers allows programs like mail
6467 user agents and web browsers to invoke these handlers to
6468 view, edit or display MIME types they don't support directly.
6472 Packages which provide the ability to view/show/play,
6473 compose, edit or print MIME types should register themselves
6474 as such following the current MIME support policy.
6478 The MIME support policy can be found in the <tt>mime-policy</tt>
6479 files in the <tt>debian-policy</tt> package.
6480 It is also available from the Debian web mirrors at
6481 <tt><url name="/doc/packaging-manuals/mime-policy/"
6482 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6488 <heading>Keyboard configuration</heading>
6491 To achieve a consistent keyboard configuration so that all
6492 applications interpret a keyboard event the same way, all
6493 programs in the Debian distribution must be configured to
6494 comply with the following guidelines.
6498 The following keys must have the specified interpretations:
6501 <tag><tt><--</tt></tag>
6502 <item>delete the character to the left of the cursor</item>
6504 <tag><tt>Delete</tt></tag>
6505 <item>delete the character to the right of the cursor</item>
6507 <tag><tt>Control+H</tt></tag>
6508 <item>emacs: the help prefix</item>
6511 The interpretation of any keyboard events should be
6512 independent of the terminal that is used, be it a virtual
6513 console, an X terminal emulator, an rlogin/telnet session,
6518 The following list explains how the different programs
6519 should be set up to achieve this:
6525 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6529 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6533 X translations are set up to make
6534 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6535 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6536 is the vt220 escape code for the "delete character"
6537 key). This must be done by loading the X resources
6538 using <prgn>xrdb</prgn> on all local X displays, not
6539 using the application defaults, so that the
6540 translation resources used correspond to the
6541 <prgn>xmodmap</prgn> settings.
6545 The Linux console is configured to make
6546 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6547 generate <tt>ESC [ 3 ~</tt>.
6551 X applications are configured so that <tt><</tt>
6552 deletes left, and <tt>Delete</tt> deletes right. Motif
6553 applications already work like this.
6557 Terminals should have <tt>stty erase ^?</tt> .
6561 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6562 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6563 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6567 Emacs is programmed to map <tt>KB_Backspace</tt> or
6568 the <tt>stty erase</tt> character to
6569 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6570 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6571 <tt>^H</tt> to <tt>help</tt> as always.
6575 Other applications use the <tt>stty erase</tt>
6576 character and <tt>kdch1</tt> for the two delete keys,
6577 with ASCII DEL being "delete previous character" and
6578 <tt>kdch1</tt> being "delete character under
6586 This will solve the problem except for the following
6593 Some terminals have a <tt><--</tt> key that cannot
6594 be made to produce anything except <tt>^H</tt>. On
6595 these terminals Emacs help will be unavailable on
6596 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6597 character takes precedence in Emacs, and has been set
6598 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6599 available) can be used instead.
6603 Some operating systems use <tt>^H</tt> for <tt>stty
6604 erase</tt>. However, modern telnet versions and all
6605 rlogin versions propagate <tt>stty</tt> settings, and
6606 almost all UNIX versions honour <tt>stty erase</tt>.
6607 Where the <tt>stty</tt> settings are not propagated
6608 correctly, things can be made to work by using
6609 <tt>stty</tt> manually.
6613 Some systems (including previous Debian versions) use
6614 <prgn>xmodmap</prgn> to arrange for both
6615 <tt><--</tt> and <tt>Delete</tt> to generate
6616 <tt>KB_Delete</tt>. We can change the behavior of
6617 their X clients using the same X resources that we use
6618 to do it for our own clients, or configure our clients
6619 using their resources when things are the other way
6620 around. On displays configured like this
6621 <tt>Delete</tt> will not work, but <tt><--</tt>
6626 Some operating systems have different <tt>kdch1</tt>
6627 settings in their <tt>terminfo</tt> database for
6628 <tt>xterm</tt> and others. On these systems the
6629 <tt>Delete</tt> key will not work correctly when you
6630 log in from a system conforming to our policy, but
6631 <tt><--</tt> will.
6638 <heading>Environment variables</heading>
6641 A program must not depend on environment variables to get
6642 reasonable defaults. (That's because these environment
6643 variables would have to be set in a system-wide
6644 configuration file like <file>/etc/profile</file>, which is not
6645 supported by all shells.)
6649 If a program usually depends on environment variables for its
6650 configuration, the program should be changed to fall back to
6651 a reasonable default configuration if these environment
6652 variables are not present. If this cannot be done easily
6653 (e.g., if the source code of a non-free program is not
6654 available), the program must be replaced by a small
6655 "wrapper" shell script which sets the environment variables
6656 if they are not already defined, and calls the original program.
6660 Here is an example of a wrapper script for this purpose:
6662 <example compact="compact">
6664 BAR=${BAR:-/var/lib/fubar}
6666 exec /usr/lib/foo/foo "$@"
6671 Furthermore, as <file>/etc/profile</file> is a configuration
6672 file of the <prgn>base-files</prgn> package, other packages must
6673 not put any environment variables or other commands into that
6678 <sect id="doc-base">
6679 <heading>Registering Documents using doc-base</heading>
6682 The <package>doc-base</package> package implements a
6683 flexible mechanism for handling and presenting
6684 documentation. The recommended practice is for every Debian
6685 package that provides online documentation (other than just
6686 manual pages) to register these documents with
6687 <package>doc-base</package> by installing a
6688 <package>doc-base</package> control file via the
6689 <prgn/install-docs/ script at installation time and
6690 de-register the manuals again when the package is removed.
6693 Please refer to the documentation that comes with the
6694 <package>doc-base</package> package for information and
6703 <heading>Files</heading>
6706 <heading>Binaries</heading>
6709 Two different packages must not install programs with
6710 different functionality but with the same filenames. (The
6711 case of two programs having the same functionality but
6712 different implementations is handled via "alternatives" or
6713 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6714 <ref id="conflicts"> respectively.) If this case happens,
6715 one of the programs must be renamed. The maintainers should
6716 report this to the <tt>debian-devel</tt> mailing list and
6717 try to find a consensus about which program will have to be
6718 renamed. If a consensus cannot be reached, <em>both</em>
6719 programs must be renamed.
6723 By default, when a package is being built, any binaries
6724 created should include debugging information, as well as
6725 being compiled with optimization. You should also turn on
6726 as many reasonable compilation warnings as possible; this
6727 makes life easier for porters, who can then look at build
6728 logs for possible problems. For the C programming language,
6729 this means the following compilation parameters should be
6731 <example compact="compact">
6733 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6735 INSTALL = install -s # (or use strip on the files in debian/tmp)
6740 Note that by default all installed binaries should be stripped,
6741 either by using the <tt>-s</tt> flag to
6742 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6743 the binaries after they have been copied into
6744 <file>debian/tmp</file> but before the tree is made into a
6749 Although binaries in the build tree should be compiled with
6750 debugging information by default, it can often be difficult to
6751 debug programs if they are also subjected to compiler
6752 optimization. For this reason, it is recommended to support the
6753 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
6754 (see <ref id="debianrules-options">). This variable can contain
6755 several flags to change how a package is compiled and built.
6759 It is up to the package maintainer to decide what
6760 compilation options are best for the package. Certain
6761 binaries (such as computationally-intensive programs) will
6762 function better with certain flags (<tt>-O3</tt>, for
6763 example); feel free to use them. Please use good judgment
6764 here. Don't use flags for the sake of it; only use them
6765 if there is good reason to do so. Feel free to override
6766 the upstream author's ideas about which compilation
6767 options are best: they are often inappropriate for our
6773 <sect id="libraries">
6774 <heading>Libraries</heading>
6777 If the package is <strong>architecture: any</strong>, then
6778 the shared library compilation and linking flags must have
6779 <tt>-fPIC</tt>, or the package shall not build on some of
6780 the supported architectures<footnote>
6782 If you are using GCC, <tt>-fPIC</tt> produces code with
6783 relocatable position independent code, which is required for
6784 most architectures to create a shared library, with i386 and
6785 perhaps some others where non position independent code is
6786 permitted in a shared library.
6789 Position independent code may have a performance penalty,
6790 especially on <tt>i386</tt>. However, in most cases the
6791 speed penalty must be measured against the memory wasted on
6792 the few architectures where non position independent code is
6795 </footnote>. Any exception to this rule must be discussed on
6796 the mailing list <em>debian-devel@lists.debian.org</em>, and
6797 a rough consensus obtained. The reasons for not compiling
6798 with <tt>-fPIC</tt> flag must be recorded in the file
6799 <tt>README.Debian</tt>, and care must be taken to either
6800 restrict the architecture or arrange for <tt>-fPIC</tt> to
6801 be used on architectures where it is required.<footnote>
6803 Some of the reasons why this might be required is if the
6804 library contains hand crafted assembly code that is not
6805 relocatable, the speed penalty is excessive for compute
6806 intensive libs, and similar reasons.
6811 As to the static libraries, the common case is not to have
6812 relocatable code, since there is no benefit, unless in specific
6813 cases; therefore the static version must not be compiled
6814 with the <tt>-fPIC</tt> flag. Any exception to this rule
6815 should be discussed on the mailing list
6816 <em>debian-devel@lists.debian.org</em>, and the reasons for
6817 compiling with the <tt>-fPIC</tt> flag must be recorded in
6818 the file <tt>README.Debian</tt>. <footnote>
6820 Some of the reasons for linking static libraries with
6821 the <tt>-fPIC</tt> flag are if, for example, one needs a
6822 Perl API for a library that is under rapid development,
6823 and has an unstable API, so shared libraries are
6824 pointless at this phase of the library's development. In
6825 that case, since Perl needs a library with relocatable
6826 code, it may make sense to create a static library with
6827 relocatable code. Another reason cited is if you are
6828 distilling various libraries into a common shared
6829 library, like <tt>mklibs</tt> does in the Debian
6835 In other words, if both a shared and a static library is
6836 being built, each source unit (<tt>*.c</tt>, for example,
6837 for C files) will need to be compiled twice, for the normal
6841 You must specify the gcc option <tt>-D_REENTRANT</tt>
6842 when building a library (either static or shared) to make
6843 the library compatible with LinuxThreads.
6847 Although not enforced by the build tools, shared libraries
6848 must be linked against all libraries that they use symbols from
6849 in the same way that binaries are. This ensures the correct
6850 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
6851 system and guarantees that all libraries can be safely opened
6852 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
6853 option <tt>-Wl,-z,defs</tt> when building a shared library.
6854 Since this option enforces symbol resolution at build time,
6855 a missing library reference will be caught early as a fatal
6860 All installed shared libraries should be stripped with
6861 <example compact="compact">
6862 strip --strip-unneeded <var>your-lib</var>
6864 (The option <tt>--strip-unneeded</tt> makes
6865 <prgn>strip</prgn> remove only the symbols which aren't
6866 needed for relocation processing.) Shared libraries can
6867 function perfectly well when stripped, since the symbols for
6868 dynamic linking are in a separate part of the ELF object
6870 You might also want to use the options
6871 <tt>--remove-section=.comment</tt> and
6872 <tt>--remove-section=.note</tt> on both shared libraries
6873 and executables, and <tt>--strip-debug</tt> on static
6879 Note that under some circumstances it may be useful to
6880 install a shared library unstripped, for example when
6881 building a separate package to support debugging.
6885 Shared object files (often <file>.so</file> files) that are not
6886 public libraries, that is, they are not meant to be linked
6887 to by third party executables (binaries of other packages),
6888 should be installed in subdirectories of the
6889 <file>/usr/lib</file> directory. Such files are exempt from the
6890 rules that govern ordinary shared libraries, except that
6891 they must not be installed executable and should be
6893 A common example are the so-called "plug-ins",
6894 internal shared objects that are dynamically loaded by
6895 programs using <manref name="dlopen" section="3">.
6900 Packages containing shared libraries that may be linked to
6901 by other packages' binaries, but which for some
6902 <em>compelling</em> reason can not be installed in
6903 <file>/usr/lib</file> directory, may install the shared library
6904 files in subdirectories of the <file>/usr/lib</file> directory,
6905 in which case they should arrange to add that directory in
6906 <file>/etc/ld.so.conf</file> in the package's post-installation
6907 script, and remove it in the package's post-removal script.
6911 An ever increasing number of packages are using
6912 <prgn>libtool</prgn> to do their linking. The latest GNU
6913 libtools (>= 1.3a) can take advantage of the metadata in the
6914 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
6915 files). The main advantage of <prgn>libtool</prgn>'s
6916 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
6917 store and subsequently access metadata with respect to the
6918 libraries it builds. <prgn>libtool</prgn> will search for
6919 those files, which contain a lot of useful information about
6920 a library (such as library dependency information for static
6921 linking). Also, they're <em>essential</em> for programs
6922 using <tt>libltdl</tt>.<footnote>
6923 Although <prgn>libtool</prgn> is fully capable of
6924 linking against shared libraries which don't have
6925 <tt>.la</tt> files, as it is a mere shell script it can
6926 add considerably to the build time of a
6927 <prgn>libtool</prgn>-using package if that shell script
6928 has to derive all this information from first principles
6929 for each library every time it is linked. With the
6930 advent of <prgn>libtool</prgn> version 1.4 (and to a
6931 lesser extent <prgn>libtool</prgn> version 1.3), the
6932 <file>.la</file> files also store information about
6933 inter-library dependencies which cannot necessarily be
6934 derived after the <file>.la</file> file is deleted.
6939 Packages that use <prgn>libtool</prgn> to create shared
6940 libraries should include the <file>.la</file> files in the
6941 <tt>-dev</tt> package, unless the package relies on
6942 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
6943 the <tt>.la</tt> files must go in the run-time library
6948 You must make sure that you use only released versions of
6949 shared libraries to build your packages; otherwise other
6950 users will not be able to run your binaries
6951 properly. Producing source packages that depend on
6952 unreleased compilers is also usually a bad
6959 <heading>Shared libraries</heading>
6961 This section has moved to <ref id="sharedlibs">.
6967 <heading>Scripts</heading>
6970 All command scripts, including the package maintainer
6971 scripts inside the package and used by <prgn>dpkg</prgn>,
6972 should have a <tt>#!</tt> line naming the shell to be used
6977 In the case of Perl scripts this should be
6978 <tt>#!/usr/bin/perl</tt>.
6982 When scripts are installed into a directory in the system
6983 PATH, the script name should not include an extension such
6984 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
6985 language currently used to implement it.
6988 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
6989 should almost certainly start with <tt>set -e</tt> so that
6990 errors are detected. Every script should use
6991 <tt>set -e</tt> or check the exit status of <em>every</em>
6996 Scripts may assume that <file>/bin/sh</file> implements the
6997 SUSv3 Shell Command Language<footnote>
6998 Single UNIX Specification, version 3, which is also IEEE
6999 1003.1-2004 (POSIX), and is available on the World Wide Web
7000 from <url id="http://www.unix.org/version3/online.html"
7001 name="The Open Group"> after free
7002 registration.</footnote>
7003 plus the following additional features not mandated by
7005 These features are in widespread use in the Linux community
7006 and are implemented in all of bash, dash, and ksh, the most
7007 common shells users may wish to use as <file>/bin/sh</file>.
7010 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7011 must not generate a newline.</item>
7012 <item><tt>test</tt>, if implemented as a shell built-in, must
7013 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7015 <item><tt>local</tt> to create a scoped variable must be
7016 supported, including listing multiple variables in a single
7017 local command and assigning a value to a variable at the
7018 same time as localizing it. <tt>local</tt> may or
7019 may not preserve the variable value from an outer scope if
7020 no assignment is present. Uses such as:
7024 # ... use a, b, c, d ...
7027 must be supported and must set the value of <tt>c</tt> to
7031 If a shell script requires non-SUSv3 features from the shell
7032 interpreter other than those listed above, the appropriate shell
7033 must be specified in the first line of the script (e.g.,
7034 <tt>#!/bin/bash</tt>) and the package must depend on the package
7035 providing the shell (unless the shell package is marked
7036 "Essential", as in the case of <prgn>bash</prgn>).
7040 You may wish to restrict your script to SUSv3 features plus the
7041 above set when possible so that it may use <file>/bin/sh</file>
7042 as its interpreter. If your script works with <prgn>dash</prgn>
7043 (originally called <prgn>ash</prgn>), it probably complies with
7044 the above requirements, but if you are in doubt, use
7045 <file>/bin/bash</file>.
7049 Perl scripts should check for errors when making any
7050 system calls, including <tt>open</tt>, <tt>print</tt>,
7051 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7055 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7056 scripting languages. See <em>Csh Programming Considered
7057 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7058 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7059 If an upstream package comes with <prgn>csh</prgn> scripts
7060 then you must make sure that they start with
7061 <tt>#!/bin/csh</tt> and make your package depend on the
7062 <prgn>c-shell</prgn> virtual package.
7066 Any scripts which create files in world-writeable
7067 directories (e.g., in <file>/tmp</file>) must use a
7068 mechanism which will fail atomically if a file with the same
7069 name already exists.
7073 The Debian base system provides the <prgn>tempfile</prgn>
7074 and <prgn>mktemp</prgn> utilities for use by scripts for
7081 <heading>Symbolic links</heading>
7084 In general, symbolic links within a top-level directory
7085 should be relative, and symbolic links pointing from one
7086 top-level directory into another should be absolute. (A
7087 top-level directory is a sub-directory of the root
7088 directory <file>/</file>.)
7092 In addition, symbolic links should be specified as short as
7093 possible, i.e., link targets like <file>foo/../bar</file> are
7098 Note that when creating a relative link using
7099 <prgn>ln</prgn> it is not necessary for the target of the
7100 link to exist relative to the working directory you're
7101 running <prgn>ln</prgn> from, nor is it necessary to change
7102 directory to the directory where the link is to be made.
7103 Simply include the string that should appear as the target
7104 of the link (this will be a pathname relative to the
7105 directory in which the link resides) as the first argument
7110 For example, in your <prgn>Makefile</prgn> or
7111 <file>debian/rules</file>, you can do things like:
7112 <example compact="compact">
7113 ln -fs gcc $(prefix)/bin/cc
7114 ln -fs gcc debian/tmp/usr/bin/cc
7115 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7116 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7121 A symbolic link pointing to a compressed file should always
7122 have the same file extension as the referenced file. (For
7123 example, if a file <file>foo.gz</file> is referenced by a
7124 symbolic link, the filename of the link has to end with
7125 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7130 <heading>Device files</heading>
7133 Packages must not include device files in the package file
7138 If a package needs any special device files that are not
7139 included in the base system, it must call
7140 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7141 after notifying the user<footnote>
7142 This notification could be done via a (low-priority)
7143 debconf message, or an echo (printf) statement.
7148 Packages must not remove any device files in the
7149 <prgn>postrm</prgn> or any other script. This is left to the
7150 system administrator.
7154 Debian uses the serial devices
7155 <file>/dev/ttyS*</file>. Programs using the old
7156 <file>/dev/cu*</file> devices should be changed to use
7157 <file>/dev/ttyS*</file>.
7161 <sect id="config-files">
7162 <heading>Configuration files</heading>
7165 <heading>Definitions</heading>
7169 <tag>configuration file</tag>
7171 A file that affects the operation of a program, or
7172 provides site- or host-specific information, or
7173 otherwise customizes the behavior of a program.
7174 Typically, configuration files are intended to be
7175 modified by the system administrator (if needed or
7176 desired) to conform to local policy or to provide
7177 more useful site-specific behavior.
7180 <tag><tt>conffile</tt></tag>
7182 A file listed in a package's <tt>conffiles</tt>
7183 file, and is treated specially by <prgn>dpkg</prgn>
7184 (see <ref id="configdetails">).
7190 The distinction between these two is important; they are
7191 not interchangeable concepts. Almost all
7192 <tt>conffile</tt>s are configuration files, but many
7193 configuration files are not <tt>conffiles</tt>.
7197 As noted elsewhere, <file>/etc/init.d</file> scripts,
7198 <file>/etc/default</file> files, scripts installed in
7199 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7200 configuration installed in <file>/etc/cron.d</file> must be
7201 treated as configuration files. In general, any script that
7202 embeds configuration information is de-facto a configuration
7203 file and should be treated as such.
7208 <heading>Location</heading>
7211 Any configuration files created or used by your package
7212 must reside in <file>/etc</file>. If there are several,
7213 consider creating a subdirectory of <file>/etc</file>
7214 named after your package.
7218 If your package creates or uses configuration files
7219 outside of <file>/etc</file>, and it is not feasible to modify
7220 the package to use <file>/etc</file> directly, put the files
7221 in <file>/etc</file> and create symbolic links to those files
7222 from the location that the package requires.
7227 <heading>Behavior</heading>
7230 Configuration file handling must conform to the following
7232 <list compact="compact">
7234 local changes must be preserved during a package
7238 configuration files must be preserved when the
7239 package is removed, and only deleted when the
7246 The easy way to achieve this behavior is to make the
7247 configuration file a <tt>conffile</tt>. This is
7248 appropriate only if it is possible to distribute a default
7249 version that will work for most installations, although
7250 some system administrators may choose to modify it. This
7251 implies that the default version will be part of the
7252 package distribution, and must not be modified by the
7253 maintainer scripts during installation (or at any other
7258 In order to ensure that local changes are preserved
7259 correctly, no package may contain or make hard links to
7260 conffiles.<footnote>
7261 Rationale: There are two problems with hard links.
7262 The first is that some editors break the link while
7263 editing one of the files, so that the two files may
7264 unwittingly become unlinked and different. The second
7265 is that <prgn>dpkg</prgn> might break the hard link
7266 while upgrading <tt>conffile</tt>s.
7271 The other way to do it is via the maintainer scripts. In
7272 this case, the configuration file must not be listed as a
7273 <tt>conffile</tt> and must not be part of the package
7274 distribution. If the existence of a file is required for
7275 the package to be sensibly configured it is the
7276 responsibility of the package maintainer to provide
7277 maintainer scripts which correctly create, update and
7278 maintain the file and remove it on purge. (See <ref
7279 id="maintainerscripts"> for more information.) These
7280 scripts must be idempotent (i.e., must work correctly if
7281 <prgn>dpkg</prgn> needs to re-run them due to errors
7282 during installation or removal), must cope with all the
7283 variety of ways <prgn>dpkg</prgn> can call maintainer
7284 scripts, must not overwrite or otherwise mangle the user's
7285 configuration without asking, must not ask unnecessary
7286 questions (particularly during upgrades), and must
7287 otherwise be good citizens.
7291 The scripts are not required to configure every possible
7292 option for the package, but only those necessary to get
7293 the package running on a given system. Ideally the
7294 sysadmin should not have to do any configuration other
7295 than that done (semi-)automatically by the
7296 <prgn>postinst</prgn> script.
7300 A common practice is to create a script called
7301 <file><var>package</var>-configure</file> and have the
7302 package's <prgn>postinst</prgn> call it if and only if the
7303 configuration file does not already exist. In certain
7304 cases it is useful for there to be an example or template
7305 file which the maintainer scripts use. Such files should
7306 be in <file>/usr/share/<var>package</var></file> or
7307 <file>/usr/lib/<var>package</var></file> (depending on whether
7308 they are architecture-independent or not). There should
7309 be symbolic links to them from
7310 <file>/usr/share/doc/<var>package</var>/examples</file> if
7311 they are examples, and should be perfectly ordinary
7312 <prgn>dpkg</prgn>-handled files (<em>not</em>
7313 configuration files).
7317 These two styles of configuration file handling must
7318 not be mixed, for that way lies madness:
7319 <prgn>dpkg</prgn> will ask about overwriting the file
7320 every time the package is upgraded.
7325 <heading>Sharing configuration files</heading>
7328 Packages which specify the same file as a
7329 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7330 with each other. (This is an instance of the general rule
7331 about not sharing files. Note that neither alternatives
7332 nor diversions are likely to be appropriate in this case;
7333 in particular, <prgn>dpkg</prgn> does not handle diverted
7334 <tt>conffile</tt>s well.)
7338 The maintainer scripts must not alter a <tt>conffile</tt>
7339 of <em>any</em> package, including the one the scripts
7344 If two or more packages use the same configuration file
7345 and it is reasonable for both to be installed at the same
7346 time, one of these packages must be defined as
7347 <em>owner</em> of the configuration file, i.e., it will be
7348 the package which handles that file as a configuration
7349 file. Other packages that use the configuration file must
7350 depend on the owning package if they require the
7351 configuration file to operate. If the other package will
7352 use the configuration file if present, but is capable of
7353 operating without it, no dependency need be declared.
7357 If it is desirable for two or more related packages to
7358 share a configuration file <em>and</em> for all of the
7359 related packages to be able to modify that configuration
7360 file, then the following should be done:
7361 <enumlist compact="compact">
7363 One of the related packages (the "owning" package)
7364 will manage the configuration file with maintainer
7365 scripts as described in the previous section.
7368 The owning package should also provide a program
7369 that the other packages may use to modify the
7373 The related packages must use the provided program
7374 to make any desired modifications to the
7375 configuration file. They should either depend on
7376 the core package to guarantee that the configuration
7377 modifier program is available or accept gracefully
7378 that they cannot modify the configuration file if it
7379 is not. (This is in addition to the fact that the
7380 configuration file may not even be present in the
7387 Sometimes it's appropriate to create a new package which
7388 provides the basic infrastructure for the other packages
7389 and which manages the shared configuration files. (The
7390 <tt>sgml-base</tt> package is a good example.)
7395 <heading>User configuration files ("dotfiles")</heading>
7398 The files in <file>/etc/skel</file> will automatically be
7399 copied into new user accounts by <prgn>adduser</prgn>.
7400 No other program should reference the files in
7401 <file>/etc/skel</file>.
7405 Therefore, if a program needs a dotfile to exist in
7406 advance in <file>$HOME</file> to work sensibly, that dotfile
7407 should be installed in <file>/etc/skel</file> and treated as a
7412 However, programs that require dotfiles in order to
7413 operate sensibly are a bad thing, unless they do create
7414 the dotfiles themselves automatically.
7418 Furthermore, programs should be configured by the Debian
7419 default installation to behave as closely to the upstream
7420 default behavior as possible.
7424 Therefore, if a program in a Debian package needs to be
7425 configured in some way in order to operate sensibly, that
7426 should be done using a site-wide configuration file placed
7427 in <file>/etc</file>. Only if the program doesn't support a
7428 site-wide default configuration and the package maintainer
7429 doesn't have time to add it may a default per-user file be
7430 placed in <file>/etc/skel</file>.
7434 <file>/etc/skel</file> should be as empty as we can make it.
7435 This is particularly true because there is no easy (or
7436 necessarily desirable) mechanism for ensuring that the
7437 appropriate dotfiles are copied into the accounts of
7438 existing users when a package is installed.
7444 <heading>Log files</heading>
7446 Log files should usually be named
7447 <file>/var/log/<var>package</var>.log</file>. If you have many
7448 log files, or need a separate directory for permission
7449 reasons (<file>/var/log</file> is writable only by
7450 <file>root</file>), you should usually create a directory named
7451 <file>/var/log/<var>package</var></file> and place your log
7456 Log files must be rotated occasionally so that they don't
7457 grow indefinitely; the best way to do this is to drop a log
7458 rotation configuration file into the directory
7459 <file>/etc/logrotate.d</file> and use the facilities provided by
7460 logrotate.<footnote>
7462 The traditional approach to log files has been to set up
7463 <em>ad hoc</em> log rotation schemes using simple shell
7464 scripts and cron. While this approach is highly
7465 customizable, it requires quite a lot of sysadmin work.
7466 Even though the original Debian system helped a little
7467 by automatically installing a system which can be used
7468 as a template, this was deemed not enough.
7472 The use of <prgn>logrotate</prgn>, a program developed
7473 by Red Hat, is better, as it centralizes log management.
7474 It has both a configuration file
7475 (<file>/etc/logrotate.conf</file>) and a directory where
7476 packages can drop their individual log rotation
7477 configurations (<file>/etc/logrotate.d</file>).
7480 Here is a good example for a logrotate config
7481 file (for more information see <manref name="logrotate"
7483 <example compact="compact">
7484 /var/log/foo/*.log {
7489 /etc/init.d/foo force-reload
7493 This rotates all files under <file>/var/log/foo</file>, saves 12
7494 compressed generations, and forces the daemon to reload its
7495 configuration information after the log rotation.
7499 Log files should be removed when the package is
7500 purged (but not when it is only removed). This should be
7501 done by the <prgn>postrm</prgn> script when it is called
7502 with the argument <tt>purge</tt> (see <ref
7503 id="removedetails">).
7508 <heading>Permissions and owners</heading>
7511 The rules in this section are guidelines for general use.
7512 If necessary you may deviate from the details below.
7513 However, if you do so you must make sure that what is done
7514 is secure and you should try to be as consistent as possible
7515 with the rest of the system. You should probably also
7516 discuss it on <prgn>debian-devel</prgn> first.
7520 Files should be owned by <tt>root:root</tt>, and made
7521 writable only by the owner and universally readable (and
7522 executable, if appropriate), that is mode 644 or 755.
7526 Directories should be mode 755 or (for group-writability)
7527 mode 2775. The ownership of the directory should be
7528 consistent with its mode: if a directory is mode 2775, it
7529 should be owned by the group that needs write access to
7532 When a package is upgraded, and the owner or permissions
7533 of a file included in the package has changed, dpkg
7534 arranges for the ownership and permissions to be
7535 correctly set upon installation. However, this does not
7536 extend to directories; the permissions and ownership of
7537 directories already on the system does not change on
7538 install or upgrade of packages. This makes sense, since
7539 otherwise common directories like <tt>/usr</tt> would
7540 always be in flux. To correctly change permissions of a
7541 directory the package owns, explicit action is required,
7542 usually in the <tt>postinst</tt> script. Care must be
7543 taken to handle downgrades as well, in that case.
7550 Setuid and setgid executables should be mode 4755 or 2755
7551 respectively, and owned by the appropriate user or group.
7552 They should not be made unreadable (modes like 4711 or
7553 2711 or even 4111); doing so achieves no extra security,
7554 because anyone can find the binary in the freely available
7555 Debian package; it is merely inconvenient. For the same
7556 reason you should not restrict read or execute permissions
7557 on non-set-id executables.
7561 Some setuid programs need to be restricted to particular
7562 sets of users, using file permissions. In this case they
7563 should be owned by the uid to which they are set-id, and by
7564 the group which should be allowed to execute them. They
7565 should have mode 4754; again there is no point in making
7566 them unreadable to those users who must not be allowed to
7571 It is possible to arrange that the system administrator can
7572 reconfigure the package to correspond to their local
7573 security policy by changing the permissions on a binary:
7574 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7575 described below.<footnote>
7576 Ordinary files installed by <prgn>dpkg</prgn> (as
7577 opposed to <tt>conffile</tt>s and other similar objects)
7578 normally have their permissions reset to the distributed
7579 permissions when the package is reinstalled. However,
7580 the use of <prgn>dpkg-statoverride</prgn> overrides this
7581 default behavior. If you use this method, you should
7582 remember to describe <prgn>dpkg-statoverride</prgn> in
7583 the package documentation; being a relatively new
7584 addition to Debian, it is probably not yet well-known.
7586 Another method you should consider is to create a group for
7587 people allowed to use the program(s) and make any setuid
7588 executables executable only by that group.
7592 If you need to create a new user or group for your package
7593 there are two possibilities. Firstly, you may need to
7594 make some files in the binary package be owned by this
7595 user or group, or you may need to compile the user or
7596 group id (rather than just the name) into the binary
7597 (though this latter should be avoided if possible, as in
7598 this case you need a statically allocated id).</p>
7601 If you need a statically allocated id, you must ask for a
7602 user or group id from the <tt>base-passwd</tt> maintainer,
7603 and must not release the package until you have been
7604 allocated one. Once you have been allocated one you must
7605 either make the package depend on a version of the
7606 <tt>base-passwd</tt> package with the id present in
7607 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7608 your package to create the user or group itself with the
7609 correct id (using <tt>adduser</tt>) in its
7610 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7611 the <prgn>postinst</prgn> is to be preferred if it is
7612 possible, otherwise a pre-dependency will be needed on the
7613 <tt>adduser</tt> package.)
7617 On the other hand, the program might be able to determine
7618 the uid or gid from the user or group name at runtime, so
7619 that a dynamically allocated id can be used. In this case
7620 you should choose an appropriate user or group name,
7621 discussing this on <prgn>debian-devel</prgn> and checking
7622 with the <package/base-passwd/ maintainer that it is unique and that
7623 they do not wish you to use a statically allocated id
7624 instead. When this has been checked you must arrange for
7625 your package to create the user or group if necessary using
7626 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7627 <prgn>postinst</prgn> script (again, the latter is to be
7628 preferred if it is possible).
7632 Note that changing the numeric value of an id associated
7633 with a name is very difficult, and involves searching the
7634 file system for all appropriate files. You need to think
7635 carefully whether a static or dynamic id is required, since
7636 changing your mind later will cause problems.
7639 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7641 This section is not intended as policy, but as a
7642 description of the use of <prgn>dpkg-statoverride</prgn>.
7646 If a system administrator wishes to have a file (or
7647 directory or other such thing) installed with owner and
7648 permissions different from those in the distributed Debian
7649 package, they can use the <prgn>dpkg-statoverride</prgn>
7650 program to instruct <prgn>dpkg</prgn> to use the different
7651 settings every time the file is installed. Thus the
7652 package maintainer should distribute the files with their
7653 normal permissions, and leave it for the system
7654 administrator to make any desired changes. For example, a
7655 daemon which is normally required to be setuid root, but
7656 in certain situations could be used without being setuid,
7657 should be installed setuid in the <tt>.deb</tt>. Then the
7658 local system administrator can change this if they wish.
7659 If there are two standard ways of doing it, the package
7660 maintainer can use <tt>debconf</tt> to find out the
7661 preference, and call <prgn>dpkg-statoverride</prgn> in the
7662 maintainer script if necessary to accommodate the system
7663 administrator's choice. Care must be taken during
7664 upgrades to not override an existing setting.
7668 Given the above, <prgn>dpkg-statoverride</prgn> is
7669 essentially a tool for system administrators and would not
7670 normally be needed in the maintainer scripts. There is
7671 one type of situation, though, where calls to
7672 <prgn>dpkg-statoverride</prgn> would be needed in the
7673 maintainer scripts, and that involves packages which use
7674 dynamically allocated user or group ids. In such a
7675 situation, something like the following idiom can be very
7676 helpful in the package's <prgn>postinst</prgn>, where
7677 <tt>sysuser</tt> is a dynamically allocated id:
7679 for i in /usr/bin/foo /usr/sbin/bar
7681 # only do something when no setting exists
7682 if ! dpkg-statoverride --list $i >/dev/null 2>&1
7684 #include: debconf processing, question about foo and bar
7685 if [ "$RET" = "true" ] ; then
7686 dpkg-statoverride --update --add sysuser root 4755 $i
7691 The corresponding <tt>dpkg-statoverride --remove</tt>
7692 calls can then be made unconditionally when the package is
7700 <chapt id="customized-programs">
7701 <heading>Customized programs</heading>
7703 <sect id="arch-spec">
7704 <heading>Architecture specification strings</heading>
7707 If a program needs to specify an <em>architecture specification
7708 string</em> in some place, it should select one of the
7709 strings provided by <tt>dpkg-architecture -L</tt>. The
7710 strings are in the format
7711 <tt><var>os</var>-<var>arch</var></tt>, though the OS part
7712 is sometimes elided, as when the OS is Linux.<footnote>
7713 <p>Currently, the strings are:
7714 i386 ia64 alpha amd64 armeb arm hppa m32r m68k mips
7715 mipsel powerpc ppc64 s390 s390x sh3 sh3eb sh4 sh4eb
7716 sparc darwin-i386 darwin-ia64 darwin-alpha darwin-amd64
7717 darwin-armeb darwin-arm darwin-hppa darwin-m32r
7718 darwin-m68k darwin-mips darwin-mipsel darwin-powerpc
7719 darwin-ppc64 darwin-s390 darwin-s390x darwin-sh3
7720 darwin-sh3eb darwin-sh4 darwin-sh4eb darwin-sparc
7721 freebsd-i386 freebsd-ia64 freebsd-alpha freebsd-amd64
7722 freebsd-armeb freebsd-arm freebsd-hppa freebsd-m32r
7723 freebsd-m68k freebsd-mips freebsd-mipsel freebsd-powerpc
7724 freebsd-ppc64 freebsd-s390 freebsd-s390x freebsd-sh3
7725 freebsd-sh3eb freebsd-sh4 freebsd-sh4eb freebsd-sparc
7726 kfreebsd-i386 kfreebsd-ia64 kfreebsd-alpha
7727 kfreebsd-amd64 kfreebsd-armeb kfreebsd-arm kfreebsd-hppa
7728 kfreebsd-m32r kfreebsd-m68k kfreebsd-mips
7729 kfreebsd-mipsel kfreebsd-powerpc kfreebsd-ppc64
7730 kfreebsd-s390 kfreebsd-s390x kfreebsd-sh3 kfreebsd-sh3eb
7731 kfreebsd-sh4 kfreebsd-sh4eb kfreebsd-sparc knetbsd-i386
7732 knetbsd-ia64 knetbsd-alpha knetbsd-amd64 knetbsd-armeb
7733 knetbsd-arm knetbsd-hppa knetbsd-m32r knetbsd-m68k
7734 knetbsd-mips knetbsd-mipsel knetbsd-powerpc
7735 knetbsd-ppc64 knetbsd-s390 knetbsd-s390x knetbsd-sh3
7736 knetbsd-sh3eb knetbsd-sh4 knetbsd-sh4eb knetbsd-sparc
7737 netbsd-i386 netbsd-ia64 netbsd-alpha netbsd-amd64
7738 netbsd-armeb netbsd-arm netbsd-hppa netbsd-m32r
7739 netbsd-m68k netbsd-mips netbsd-mipsel netbsd-powerpc
7740 netbsd-ppc64 netbsd-s390 netbsd-s390x netbsd-sh3
7741 netbsd-sh3eb netbsd-sh4 netbsd-sh4eb netbsd-sparc
7742 openbsd-i386 openbsd-ia64 openbsd-alpha openbsd-amd64
7743 openbsd-armeb openbsd-arm openbsd-hppa openbsd-m32r
7744 openbsd-m68k openbsd-mips openbsd-mipsel openbsd-powerpc
7745 openbsd-ppc64 openbsd-s390 openbsd-s390x openbsd-sh3
7746 openbsd-sh3eb openbsd-sh4 openbsd-sh4eb openbsd-sparc
7747 hurd-i386 hurd-ia64 hurd-alpha hurd-amd64 hurd-armeb
7748 hurd-arm hurd-hppa hurd-m32r hurd-m68k hurd-mips
7749 hurd-mipsel hurd-powerpc hurd-ppc64 hurd-s390 hurd-s390x
7750 hurd-sh3 hurd-sh3eb hurd-sh4 hurd-sh4eb hurd-sparc
7756 Note that we don't want to use
7757 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7758 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7759 since this would make our programs incompatible with other
7760 Linux distributions. We also don't use something like
7761 <tt><var>arch</var>-unknown-linux</tt>, since the
7762 <tt>unknown</tt> does not look very good.
7767 <heading>Daemons</heading>
7770 The configuration files <file>/etc/services</file>,
7771 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7772 by the <prgn>netbase</prgn> package and must not be modified
7777 If a package requires a new entry in one of these files, the
7778 maintainer should get in contact with the
7779 <prgn>netbase</prgn> maintainer, who will add the entries
7780 and release a new version of the <prgn>netbase</prgn>
7785 The configuration file <file>/etc/inetd.conf</file> must not be
7786 modified by the package's scripts except via the
7787 <prgn>update-inetd</prgn> script or the
7788 <file>DebianNet.pm</file> Perl module. See their documentation
7789 for details on how to add entries.
7793 If a package wants to install an example entry into
7794 <file>/etc/inetd.conf</file>, the entry must be preceded with
7795 exactly one hash character (<tt>#</tt>). Such lines are
7796 treated as "commented out by user" by the
7797 <prgn>update-inetd</prgn> script and are not changed or
7798 activated during package updates.
7803 <heading>Using pseudo-ttys and modifying wtmp, utmp and
7807 Some programs need to create pseudo-ttys. This should be done
7808 using Unix98 ptys if the C library supports it. The resulting
7809 program must not be installed setuid root, unless that
7810 is required for other functionality.
7814 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
7815 <file>/var/log/lastlog</file> must be installed writable by
7816 group <tt>utmp</tt>. Programs which need to modify those
7817 files must be installed setgid <tt>utmp</tt>.
7822 <heading>Editors and pagers</heading>
7825 Some programs have the ability to launch an editor or pager
7826 program to edit or display a text document. Since there are
7827 lots of different editors and pagers available in the Debian
7828 distribution, the system administrator and each user should
7829 have the possibility to choose their preferred editor and
7834 In addition, every program should choose a good default
7835 editor/pager if none is selected by the user or system
7840 Thus, every program that launches an editor or pager must
7841 use the EDITOR or PAGER environment variable to determine
7842 the editor or pager the user wishes to use. If these
7843 variables are not set, the programs <file>/usr/bin/editor</file>
7844 and <file>/usr/bin/pager</file> should be used, respectively.
7848 These two files are managed through the <prgn>dpkg</prgn>
7849 "alternatives" mechanism. Thus every package providing an
7850 editor or pager must call the
7851 <prgn>update-alternatives</prgn> script to register these
7856 If it is very hard to adapt a program to make use of the
7857 EDITOR or PAGER variables, that program may be configured to
7858 use <file>/usr/bin/sensible-editor</file> and
7859 <file>/usr/bin/sensible-pager</file> as the editor or pager
7860 program respectively. These are two scripts provided in the
7861 Debian base system that check the EDITOR and PAGER variables
7862 and launch the appropriate program, and fall back to
7863 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
7864 variable is not set.
7868 A program may also use the VISUAL environment variable to
7869 determine the user's choice of editor. If it exists, it
7870 should take precedence over EDITOR. This is in fact what
7871 <file>/usr/bin/sensible-editor</file> does.
7875 It is not required for a package to depend on
7876 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
7877 package to provide such virtual packages.<footnote>
7878 The Debian base system already provides an editor and a
7884 <sect id="web-appl">
7885 <heading>Web servers and applications</heading>
7888 This section describes the locations and URLs that should
7889 be used by all web servers and web applications in the
7896 Cgi-bin executable files are installed in the
7898 <example compact="compact">
7899 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
7901 and should be referred to as
7902 <example compact="compact">
7903 http://localhost/cgi-bin/<var>cgi-bin-name</var>
7909 <p>Access to HTML documents</p>
7912 HTML documents for a package are stored in
7913 <file>/usr/share/doc/<var>package</var></file>
7914 and can be referred to as
7915 <example compact="compact">
7916 http://localhost/doc/<var>package</var>/<var>filename</var>
7921 The web server should restrict access to the document
7922 tree so that only clients on the same host can read
7923 the documents. If the web server does not support such
7924 access controls, then it should not provide access at
7925 all, or ask about providing access during installation.
7930 <p>Access to images</p>
7932 It is recommended that images for a package be stored
7933 in <tt>/usr/share/images/<var>package</var></tt> and
7934 may be referred to through an alias <tt>/images/</tt>
7937 http://localhost/images/<package>/<filename>
7944 <p>Web Document Root</p>
7947 Web Applications should try to avoid storing files in
7948 the Web Document Root. Instead they should use the
7949 /usr/share/doc/<var>package</var> directory for
7950 documents and register the Web Application via the
7951 <package>doc-base</package> package. If access to the
7952 web document root is unavoidable then use
7953 <example compact="compact">
7956 as the Document Root. This might be just a symbolic
7957 link to the location where the system administrator
7958 has put the real document root.
7961 <item><p>Providing httpd and/or httpd-cgi</p>
7963 All web servers should provide the virtual package
7964 <tt>httpd</tt>. If a web server has CGI support it should
7965 provide <tt>httpd-cgi</tt> additionally.
7968 All web applications which do not contain CGI scripts should
7969 depend on <tt>httpd</tt>, all those web applications which
7970 <tt>do</tt> contain CGI scripts, should depend on
7978 <sect id="mail-transport-agents">
7979 <heading>Mail transport, delivery and user agents</heading>
7982 Debian packages which process electronic mail, whether mail
7983 user agents (MUAs) or mail transport agents (MTAs), must
7984 ensure that they are compatible with the configuration
7985 decisions below. Failure to do this may result in lost
7986 mail, broken <tt>From:</tt> lines, and other serious brain
7991 The mail spool is <file>/var/mail</file> and the interface to
7992 send a mail message is <file>/usr/sbin/sendmail</file> (as per
7993 the FHS). On older systems, the mail spool may be
7994 physically located in <file>/var/spool/mail</file>, but all
7995 access to the mail spool should be via the
7996 <file>/var/mail</file> symlink. The mail spool is part of the
7997 base system and not part of the MTA package.
8001 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8002 programs (such as IMAP daemons) must lock the mailbox in an
8003 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8004 be combined with dot locking. To avoid deadlocks, a program
8005 should use <tt>fcntl()</tt> first and dot locking after
8006 this, or alternatively implement the two locking methods in
8007 a non blocking way<footnote>
8008 If it is not possible to establish both locks, the
8009 system shouldn't wait for the second lock to be
8010 established, but remove the first lock, wait a (random)
8011 time, and start over locking again.
8012 </footnote>. Using the functions <tt>maillock</tt> and
8013 <tt>mailunlock</tt> provided by the
8014 <tt>liblockfile*</tt><footnote>
8015 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8016 to use these functions.
8017 </footnote> packages is the recommended way to realize this.
8021 Mailboxes are generally mode 660
8022 <tt><var>user</var>:mail</tt> unless the system
8023 administrator has chosen otherwise. A MUA may remove a
8024 mailbox (unless it has nonstandard permissions) in which
8025 case the MTA or another MUA must recreate it if needed.
8026 Mailboxes must be writable by group mail.
8030 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8031 be setgid mail to do the locking mentioned above (and
8032 must obviously avoid accessing other users' mailboxes
8033 using this privilege).</p>
8036 <file>/etc/aliases</file> is the source file for the system mail
8037 aliases (e.g., postmaster, usenet, etc.), it is the one
8038 which the sysadmin and <prgn>postinst</prgn> scripts may
8039 edit. After <file>/etc/aliases</file> is edited the program or
8040 human editing it must call <prgn>newaliases</prgn>. All MTA
8041 packages must come with a <prgn>newaliases</prgn> program,
8042 even if it does nothing, but older MTA packages did not do
8043 this so programs should not fail if <prgn>newaliases</prgn>
8044 cannot be found. Note that because of this, all MTA
8045 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8046 <tt>Replaces: mail-transport-agent</tt> control file
8051 The convention of writing <tt>forward to
8052 <var>address</var></tt> in the mailbox itself is not
8053 supported. Use a <tt>.forward</tt> file instead.</p>
8056 The <prgn>rmail</prgn> program used by UUCP
8057 for incoming mail should be <file>/usr/sbin/rmail</file>.
8058 Likewise, <prgn>rsmtp</prgn>, for receiving
8059 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8063 If your package needs to know what hostname to use on (for
8064 example) outgoing news and mail messages which are generated
8065 locally, you should use the file <file>/etc/mailname</file>. It
8066 will contain the portion after the username and <tt>@</tt>
8067 (at) sign for email addresses of users on the machine
8068 (followed by a newline).
8072 Such a package should check for the existence of this file
8073 when it is being configured. If it exists, it should be
8074 used without comment, although an MTA's configuration script
8075 may wish to prompt the user even if it finds that this file
8076 exists. If the file does not exist, the package should
8077 prompt the user for the value (preferably using
8078 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8079 as well as using it in the package's configuration. The
8080 prompt should make it clear that the name will not just be
8081 used by that package. For example, in this situation the
8082 <tt>inn</tt> package could say something like:
8083 <example compact="compact">
8084 Please enter the "mail name" of your system. This is the
8085 hostname portion of the address to be shown on outgoing
8086 news and mail messages. The default is
8087 <var>syshostname</var>, your system's host name. Mail
8088 name ["<var>syshostname</var>"]:
8090 where <var>syshostname</var> is the output of <tt>hostname
8096 <heading>News system configuration</heading>
8099 All the configuration files related to the NNTP (news)
8100 servers and clients should be located under
8101 <file>/etc/news</file>.</p>
8104 There are some configuration issues that apply to a number
8105 of news clients and server packages on the machine. These
8109 <tag><file>/etc/news/organization</file></tag>
8111 A string which should appear as the
8112 organization header for all messages posted
8113 by NNTP clients on the machine
8116 <tag><file>/etc/news/server</file></tag>
8118 Contains the FQDN of the upstream NNTP
8119 server, or localhost if the local machine is
8124 Other global files may be added as required for cross-package news
8131 <heading>Programs for the X Window System</heading>
8134 <heading>Providing X support and package priorities</heading>
8137 Programs that can be configured with support for the X
8138 Window System must be configured to do so and must declare
8139 any package dependencies necessary to satisfy their
8140 runtime requirements when using the X Window System. If
8141 such a package is of higher priority than the X packages
8142 on which it depends, it is required that either the
8143 X-specific components be split into a separate package, or
8144 that an alternative version of the package, which includes
8145 X support, be provided, or that the package's priority be
8151 <heading>Packages providing an X server</heading>
8154 Packages that provide an X server that, directly or
8155 indirectly, communicates with real input and display
8156 hardware should declare in their control data that they
8157 provide the virtual package <tt>xserver</tt>.<footnote>
8158 This implements current practice, and provides an
8159 actual policy for usage of the <tt>xserver</tt>
8160 virtual package which appears in the virtual packages
8161 list. In a nutshell, X servers that interface
8162 directly with the display and input hardware or via
8163 another subsystem (e.g., GGI) should provide
8164 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8165 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8171 <heading>Packages providing a terminal emulator</heading>
8174 Packages that provide a terminal emulator for the X Window
8175 System which meet the criteria listed below should declare
8176 in their control data that they provide the virtual
8177 package <tt>x-terminal-emulator</tt>. They should also
8178 register themselves as an alternative for
8179 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8184 To be an <tt>x-terminal-emulator</tt>, a program must:
8185 <list compact="compact">
8187 Be able to emulate a DEC VT100 terminal, or a
8188 compatible terminal.
8192 Support the command-line option <tt>-e
8193 <var>command</var></tt>, which creates a new
8194 terminal window<footnote>
8195 "New terminal window" does not necessarily mean
8196 a new top-level X window directly parented by
8197 the window manager; it could, if the terminal
8198 emulator application were so coded, be a new
8199 "view" in a multiple-document interface (MDI).
8201 and runs the specified <var>command</var>,
8202 interpreting the entirety of the rest of the command
8203 line as a command to pass straight to exec, in the
8204 manner that <tt>xterm</tt> does.
8208 Support the command-line option <tt>-T
8209 <var>title</var></tt>, which creates a new terminal
8210 window with the window title <var>title</var>.
8217 <heading>Packages providing a window manager</heading>
8220 Packages that provide a window manager should declare in
8221 their control data that they provide the virtual package
8222 <tt>x-window-manager</tt>. They should also register
8223 themselves as an alternative for
8224 <file>/usr/bin/x-window-manager</file>, with a priority
8225 calculated as follows:
8226 <list compact="compact">
8228 Start with a priority of 20.
8232 If the window manager supports the Debian menu
8233 system, add 20 points if this support is available
8234 in the package's default configuration (i.e., no
8235 configuration files belonging to the system or user
8236 have to be edited to activate the feature); if
8237 configuration files must be modified, add only 10
8243 If the window manager complies with <url
8244 id="http://www.freedesktop.org/Standards/wm-spec"
8245 name="The Window Manager Specification Project">,
8246 written by the <url id="http://www.freedesktop.org/"
8247 name="Free Desktop Group">, add 40 points.
8251 If the window manager permits the X session to be
8252 restarted using a <em>different</em> window manager
8253 (without killing the X server) in its default
8254 configuration, add 10 points; otherwise add none.
8261 <heading>Packages providing fonts</heading>
8264 Packages that provide fonts for the X Window
8266 For the purposes of Debian Policy, a "font for the X
8267 Window System" is one which is accessed via X protocol
8268 requests. Fonts for the Linux console, for PostScript
8269 renderer, or any other purpose, do not fit this
8270 definition. Any tool which makes such fonts available
8271 to the X Window System, however, must abide by this
8274 must do a number of things to ensure that they are both
8275 available without modification of the X or font server
8276 configuration, and that they do not corrupt files used by
8277 other font packages to register information about
8281 Fonts of any type supported by the X Window System
8282 must be in a separate binary package from any
8283 executables, libraries, or documentation (except
8284 that specific to the fonts shipped, such as their
8285 license information). If one or more of the fonts
8286 so packaged are necessary for proper operation of
8287 the package with which they are associated the font
8288 package may be Recommended; if the fonts merely
8289 provide an enhancement, a Suggests relationship may
8290 be used. Packages must not Depend on font
8292 This is because the X server may retrieve fonts
8293 from the local file system or over the network
8294 from an X font server; the Debian package system
8295 is empowered to deal only with the local
8301 BDF fonts must be converted to PCF fonts with the
8302 <prgn>bdftopcf</prgn> utility (available in the
8303 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8304 placed in a directory that corresponds to their
8306 <list compact="compact">
8308 100 dpi fonts must be placed in
8309 <file>/usr/share/fonts/X11/100dpi/</file>.
8313 75 dpi fonts must be placed in
8314 <file>/usr/share/fonts/X11/75dpi/</file>.
8318 Character-cell fonts, cursor fonts, and other
8319 low-resolution fonts must be placed in
8320 <file>/usr/share/fonts/X11/misc/</file>.
8326 Speedo fonts must be placed in
8327 <file>/usr/share/fonts/X11/Speedo/</file>.
8331 Type 1 fonts must be placed in
8332 <file>/usr/share/fonts/X11/Type1/</file>. If font
8333 metric files are available, they must be placed here
8338 Subdirectories of <file>/usr/share/fonts/X11/</file>
8339 other than those listed above must be neither
8340 created nor used. (The <file>PEX</file>, <file>CID</file>,
8341 and <file>cyrillic</file> directories are excepted for
8342 historical reasons, but installation of files into
8343 these directories remains discouraged.)
8347 Font packages may, instead of placing files directly
8348 in the X font directories listed above, provide
8349 symbolic links in that font directory pointing to
8350 the files' actual location in the filesystem. Such
8351 a location must comply with the FHS.
8355 Font packages should not contain both 75dpi and
8356 100dpi versions of a font. If both are available,
8357 they should be provided in separate binary packages
8358 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8359 the names of the packages containing the
8360 corresponding fonts.
8364 Fonts destined for the <file>misc</file> subdirectory
8365 should not be included in the same package as 75dpi
8366 or 100dpi fonts; instead, they should be provided in
8367 a separate package with <tt>-misc</tt> appended to
8372 Font packages must not provide the files
8373 <file>fonts.dir</file>, <file>fonts.alias</file>, or
8374 <file>fonts.scale</file> in a font directory:
8377 <file>fonts.dir</file> files must not be provided at all.
8381 <file>fonts.alias</file> and <file>fonts.scale</file>
8382 files, if needed, should be provided in the
8384 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
8385 where <var>fontdir</var> is the name of the
8387 <file>/usr/share/fonts/X11/</file> where the
8388 package's corresponding fonts are stored
8389 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
8390 <var>package</var> is the name of the package
8391 that provides these fonts, and
8392 <var>extension</var> is either <tt>scale</tt>
8393 or <tt>alias</tt>, whichever corresponds to
8400 Font packages must declare a dependency on
8401 <tt>xfonts-utils</tt> in their control
8406 Font packages that provide one or more
8407 <file>fonts.scale</file> files as described above must
8408 invoke <prgn>update-fonts-scale</prgn> on each
8409 directory into which they installed fonts
8410 <em>before</em> invoking
8411 <prgn>update-fonts-dir</prgn> on that directory.
8412 This invocation must occur in both the
8413 <prgn>postinst</prgn> (for all arguments) and
8414 <prgn>postrm</prgn> (for all arguments except
8415 <tt>upgrade</tt>) scripts.
8419 Font packages that provide one or more
8420 <file>fonts.alias</file> files as described above must
8421 invoke <prgn>update-fonts-alias</prgn> on each
8422 directory into which they installed fonts. This
8423 invocation must occur in both the
8424 <prgn>postinst</prgn> (for all arguments) and
8425 <prgn>postrm</prgn> (for all arguments except
8426 <tt>upgrade</tt>) scripts.
8430 Font packages must invoke
8431 <prgn>update-fonts-dir</prgn> on each directory into
8432 which they installed fonts. This invocation must
8433 occur in both the <prgn>postinst</prgn> (for all
8434 arguments) and <prgn>postrm</prgn> (for all
8435 arguments except <tt>upgrade</tt>) scripts.
8439 Font packages must not provide alias names for the
8440 fonts they include which collide with alias names
8441 already in use by fonts already packaged.
8445 Font packages must not provide fonts with the same
8446 XLFD registry name as another font already packaged.
8453 <heading>Application defaults files</heading>
8456 Application defaults files must be installed in the
8457 directory <file>/etc/X11/app-defaults/</file> (use of a
8458 localized subdirectory of <file>/etc/X11/</file> as described
8459 in the <em>X Toolkit Intrinsics - C Language
8460 Interface</em> manual is also permitted). They must be
8461 registered as <tt>conffile</tt>s or handled as
8462 configuration files.
8466 Customization of programs' X resources may also be
8467 supported with the provision of a file with the same name
8468 as that of the package placed in the
8469 <file>/etc/X11/Xresources/</file> directory, which must
8470 registered as a <tt>conffile</tt> or handled as a
8471 configuration file.<footnote>
8472 Note that this mechanism is not the same as using
8473 app-defaults; app-defaults are tied to the client
8474 binary on the local file system, whereas X resources
8475 are stored in the X server and affect all connecting
8482 <heading>Installation directory issues</heading>
8485 Packages using the X Window System should not be
8486 configured to install files under the
8487 <file>/usr/X11R6/</file> directory. The
8488 <file>/usr/X11R6/</file> directory hierarchy should be
8489 regarded as obsolete.
8493 Programs that use GNU <prgn>autoconf</prgn> and
8494 <prgn>automake</prgn> are usually easily configured at
8495 compile time to use <file>/usr/</file> instead of
8496 <file>/usr/X11R6/</file>, and this should be done whenever
8497 possible. Configuration files for window managers and
8498 display managers should be placed in a subdirectory of
8499 <file>/etc/X11/</file> corresponding to the package name due
8500 to these programs' tight integration with the mechanisms
8501 of the X Window System. Application-level programs should
8502 use the <file>/etc/</file> directory unless otherwise mandated
8507 The installation of files into subdirectories
8508 of <file>/usr/X11R6/include/X11/</file> and
8509 <file>/usr/X11R6/lib/X11/</file> is now prohibited;
8510 package maintainers should determine if subdirectories of
8511 <file>/usr/lib/</file> and <file>/usr/share/</file> can be used
8516 Packages should install any relevant files into the
8517 directories <file>/usr/include/X11/</file> and
8518 <file>/usr/lib/X11/</file>, but if they do so, they must
8519 pre-depend on <tt>x11-common (>=
8520 1:7.0.0)</tt><footnote>
8522 These libraries used to be all symbolic
8523 links. However, with <tt>X11R7</tt>,
8524 <tt>/usr/include/X11</tt> and <tt>/usr/lib/X11</tt>
8525 are now real directories, and packages
8526 <strong>should</strong> ship their files here instead
8527 of in <tt>/usr/X11R6/{include,lib}/X11</tt>.
8528 <tt>x11-common (>= 1:7.0.0) </tt> is the package
8529 responsible for converting these symlinks into
8537 <heading>The OSF/Motif and OpenMotif libraries</heading>
8540 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8541 OpenMotif libraries</em><footnote>
8542 OSF/Motif and OpenMotif are collectively referred to as
8543 "Motif" in this policy document.
8545 should be compiled against and tested with LessTif (a free
8546 re-implementation of Motif) instead. If the maintainer
8547 judges that the program or programs do not work
8548 sufficiently well with LessTif to be distributed and
8549 supported, but do so when compiled against Motif, then two
8550 versions of the package should be created; one linked
8551 statically against Motif and with <tt>-smotif</tt>
8552 appended to the package name, and one linked dynamically
8553 against Motif and with <tt>-dmotif</tt> appended to the
8558 Both Motif-linked versions are dependent
8559 upon non-DFSG-compliant software and thus cannot be
8560 uploaded to the <em>main</em> distribution; if the
8561 software is itself DFSG-compliant it may be uploaded to
8562 the <em>contrib</em> distribution. While known existing
8563 versions of Motif permit unlimited redistribution of
8564 binaries linked against the library (whether statically or
8565 dynamically), it is the package maintainer's
8566 responsibility to determine whether this is permitted by
8567 the license of the copy of Motif in their possession.
8573 <heading>Perl programs and modules</heading>
8576 Perl programs and modules should follow the current Perl policy.
8580 The Perl policy can be found in the <tt>perl-policy</tt>
8581 files in the <tt>debian-policy</tt> package.
8582 It is also available from the Debian web mirrors at
8583 <tt><url name="/doc/packaging-manuals/perl-policy/"
8584 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8589 <heading>Emacs lisp programs</heading>
8592 Please refer to the "Debian Emacs Policy" for details of how to
8593 package emacs lisp programs.
8597 The Emacs policy is available in
8598 <file>debian-emacs-policy.gz</file> of the
8599 <package>emacsen-common</package> package.
8600 It is also available from the Debian web mirrors at
8601 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8602 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8607 <heading>Games</heading>
8610 The permissions on <file>/var/games</file> are mode 755, owner
8611 <tt>root</tt> and group <tt>root</tt>.
8615 Each game decides on its own security policy.</p>
8618 Games which require protected, privileged access to
8619 high-score files, saved games, etc., may be made
8620 set-<em>group</em>-id (mode 2755) and owned by
8621 <tt>root:games</tt>, and use files and directories with
8622 appropriate permissions (770 <tt>root:games</tt>, for
8623 example). They must not be made
8624 set-<em>user</em>-id, as this causes security problems. (If
8625 an attacker can subvert any set-user-id game they can
8626 overwrite the executable of any other, causing other players
8627 of these games to run a Trojan horse program. With a
8628 set-group-id game the attacker only gets access to less
8629 important game data, and if they can get at the other
8630 players' accounts at all it will take considerably more
8634 Some packages, for example some fortune cookie programs, are
8635 configured by the upstream authors to install with their
8636 data files or other static information made unreadable so
8637 that they can only be accessed through set-id programs
8638 provided. You should not do this in a Debian package: anyone can
8639 download the <file>.deb</file> file and read the data from it,
8640 so there is no point making the files unreadable. Not
8641 making the files unreadable also means that you don't have
8642 to make so many programs set-id, which reduces the risk of a
8646 As described in the FHS, binaries of games should be
8647 installed in the directory <file>/usr/games</file>. This also
8648 applies to games that use the X Window System. Manual pages
8649 for games (X and non-X games) should be installed in
8650 <file>/usr/share/man/man6</file>.</p>
8656 <heading>Documentation</heading>
8659 <heading>Manual pages</heading>
8662 You should install manual pages in <prgn>nroff</prgn> source
8663 form, in appropriate places under <file>/usr/share/man</file>.
8664 You should only use sections 1 to 9 (see the FHS for more
8665 details). You must not install a pre-formatted "cat page".
8669 Each program, utility, and function should have an
8670 associated manual page included in the same package. It is
8671 suggested that all configuration files also have a manual
8672 page included as well. Manual pages for protocols and other
8673 auxiliary things are optional.
8677 If no manual page is available, this is considered as a bug
8678 and should be reported to the Debian Bug Tracking System (the
8679 maintainer of the package is allowed to write this bug report
8680 themselves, if they so desire). Do not close the bug report
8681 until a proper man page is available.<footnote>
8682 It is not very hard to write a man page. See the
8683 <url id="http://www.schweikhardt.net/man_page_howto.html"
8684 name="Man-Page-HOWTO">,
8685 <manref name="man" section="7">, the examples
8686 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8687 the helper programs <prgn>help2man</prgn>, or the
8688 directory <file>/usr/share/doc/man-db/examples</file>.
8693 You may forward a complaint about a missing man page to the
8694 upstream authors, and mark the bug as forwarded in the
8695 Debian bug tracking system. Even though the GNU Project do
8696 not in general consider the lack of a man page to be a bug,
8697 we do; if they tell you that they don't consider it a bug
8698 you should leave the bug in our bug tracking system open
8703 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8707 If one man page needs to be accessible via several names it
8708 is better to use a symbolic link than the <file>.so</file>
8709 feature, but there is no need to fiddle with the relevant
8710 parts of the upstream source to change from <file>.so</file> to
8711 symlinks: don't do it unless it's easy. You should not
8712 create hard links in the manual page directories, nor put
8713 absolute filenames in <file>.so</file> directives. The filename
8714 in a <file>.so</file> in a man page should be relative to the
8715 base of the man page tree (usually
8716 <file>/usr/share/man</file>). If you do not create any links
8717 (whether symlinks, hard links, or <tt>.so</tt> directives)
8718 in the file system to the alternate names of the man page,
8719 then you should not rely on <prgn>man</prgn> finding your
8720 man page under those names based solely on the information in
8721 the man page's header.<footnote>
8722 Supporting this in <prgn>man</prgn> often requires
8723 unreasonable processing time to find a manual page or to
8724 report that none exists, and moves knowledge into man's
8725 database that would be better left in the file system.
8726 This support is therefore deprecated and will cease to
8727 be present in the future.
8732 Manual pages in locale-specific subdirectories of
8733 <file>/usr/share/man</file> should use either UTF-8 or the usual
8734 legacy encoding for that language (normally the one corresponding
8735 to the shortest relevant locale name in
8736 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
8737 <file>/usr/share/man/fr</file> should use either UTF-8 or
8738 ISO-8859-1.<footnote>
8739 <prgn>man</prgn> will automatically detect whether UTF-8 is in
8740 use. In future, all manual pages will be required to use
8746 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
8747 included in the subdirectory name unless it indicates a
8748 significant difference in the language, as this excludes
8749 speakers of the language in other countries.<footnote>
8750 At the time of writing, Chinese and Portuguese are the main
8751 languages with such differences, so <file>pt_BR</file>,
8752 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
8757 Due to limitations in current implementations, all characters
8758 in the manual page source should be representable in the usual
8759 legacy encoding for that language, even if the file is
8760 actually encoded in UTF-8. Safe alternative ways to write many
8761 characters outside that range may be found in
8762 <manref name="groff_char" section="7">.
8767 <heading>Info documents</heading>
8770 Info documents should be installed in <file>/usr/share/info</file>.
8771 They should be compressed with <tt>gzip -9</tt>.
8775 Your package should call <prgn>install-info</prgn> to update
8776 the Info <file>dir</file> file in its <prgn>postinst</prgn>
8777 script when called with a <tt>configure</tt> argument, for
8779 <example compact="compact">
8780 install-info --quiet --section Development Development \
8781 /usr/share/info/foobar.info
8785 It is a good idea to specify a section for the location of
8786 your program; this is done with the <tt>--section</tt>
8787 switch. To determine which section to use, you should look
8788 at <file>/usr/share/info/dir</file> on your system and choose the most
8789 relevant (or create a new section if none of the current
8790 sections are relevant). Note that the <tt>--section</tt>
8791 flag takes two arguments; the first is a regular expression
8792 to match (case-insensitively) against an existing section,
8793 the second is used when creating a new one.</p>
8796 You should remove the entries in the <prgn>prerm</prgn>
8797 script when called with a <tt>remove</tt> argument:
8798 <example compact="compact">
8799 install-info --quiet --remove /usr/share/info/foobar.info
8803 If <prgn>install-info</prgn> cannot find a description entry
8804 in the Info file you must supply one. See <manref
8805 name="install-info" section="8"> for details.</p>
8809 <heading>Additional documentation</heading>
8812 Any additional documentation that comes with the package may
8813 be installed at the discretion of the package maintainer.
8814 Plain text documentation should be installed in the directory
8815 <file>/usr/share/doc/<var>package</var></file>, where
8816 <var>package</var> is the name of the package, and
8817 compressed with <tt>gzip -9</tt> unless it is small.
8821 If a package comes with large amounts of documentation which
8822 many users of the package will not require you should create
8823 a separate binary package to contain it, so that it does not
8824 take up disk space on the machines of users who do not need
8825 or want it installed.</p>
8828 It is often a good idea to put text information files
8829 (<file>README</file>s, changelogs, and so forth) that come with
8830 the source package in <file>/usr/share/doc/<var>package</var></file>
8831 in the binary package. However, you don't need to install
8832 the instructions for building and installing the package, of
8836 Packages must not require the existence of any files in
8837 <file>/usr/share/doc/</file> in order to function
8839 The system administrator should be able to
8840 delete files in <file>/usr/share/doc/</file> without causing
8841 any programs to break.
8843 Any files that are referenced by programs but are also
8844 useful as stand alone documentation should be installed under
8845 <file>/usr/share/<var>package</var>/</file> with symbolic links from
8846 <file>/usr/share/doc/<var>package</var></file>.
8850 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8851 link to another directory in <file>/usr/share/doc</file> only if
8852 the two packages both come from the same source and the
8853 first package Depends on the second.<footnote>
8855 Please note that this does not override the section on
8856 changelog files below, so the file
8857 <file>/usr/share/<var>package</var>/changelog.Debian.gz</file>
8858 must refer to the changelog for the current version of
8859 <var>package</var> in question. In practice, this means
8860 that the sources of the target and the destination of the
8861 symlink must be the same (same source package and
8868 Former Debian releases placed all additional documentation
8869 in <file>/usr/doc/<var>package</var></file>. This has been
8870 changed to <file>/usr/share/doc/<var>package</var></file>,
8871 and packages must not put documentation in the directory
8872 <file>/usr/doc/<var>package</var></file>. <footnote>
8873 At this phase of the transition, we no longer require a
8874 symbolic link in <file>/usr/doc/</file>. At a later point,
8875 policy shall change to make the symbolic links a bug.
8881 <heading>Preferred documentation formats</heading>
8884 The unification of Debian documentation is being carried out
8888 If your package comes with extensive documentation in a
8889 markup format that can be converted to various other formats
8890 you should if possible ship HTML versions in a binary
8891 package, in the directory
8892 <file>/usr/share/doc/<var>appropriate-package</var></file> or
8893 its subdirectories.<footnote>
8894 The rationale: The important thing here is that HTML
8895 docs should be available in <em>some</em> package, not
8896 necessarily in the main binary package.
8901 Other formats such as PostScript may be provided at the
8902 package maintainer's discretion.
8906 <sect id="copyrightfile">
8907 <heading>Copyright information</heading>
8910 Every package must be accompanied by a verbatim copy of its
8911 copyright and distribution license in the file
8912 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
8913 file must neither be compressed nor be a symbolic link.
8917 In addition, the copyright file must say where the upstream
8918 sources (if any) were obtained. It should name the original
8919 authors of the package and the Debian maintainer(s) who were
8920 involved with its creation.
8924 Packages in the <em>contrib</em> or <em>non-free</em> categories
8925 should state in the copyright file that the package is not part
8926 of the Debian GNU/Linux distribution and briefly explain why.
8930 A copy of the file which will be installed in
8931 <file>/usr/share/doc/<var>package</var>/copyright</file> should
8932 be in <file>debian/copyright</file> in the source package.
8936 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8937 link to another directory in <file>/usr/share/doc</file> only if
8938 the two packages both come from the same source and the
8939 first package Depends on the second. These rules are
8940 important because copyrights must be extractable by
8945 Packages distributed under the UCB BSD license, the Apache
8946 license (version 2.0), the Artistic license, the GNU GPL
8947 (version 2 or 3), the GNU LGPL (versions 2, 2.1, or 3), and
8948 the GNU FDL (version 1.2) should refer to the corresponding
8949 files under <file>/usr/share/common-licenses</file>,<footnote>
8952 <file>/usr/share/common-licenses/BSD</file>,
8953 <file>/usr/share/common-licenses/Apache-2.0</file>,
8954 <file>/usr/share/common-licenses/Artistic</file>,
8955 <file>/usr/share/common-licenses/GPL-2</file>,
8956 <file>/usr/share/common-licenses/GPL-3</file>,
8957 <file>/usr/share/common-licenses/LGPL-2</file>,
8958 <file>/usr/share/common-licenses/LGPL-2.1</file>,
8959 <file>/usr/share/common-licenses/LGPL-3</file>, and
8960 <file>/usr/share/common-licenses/GFDL-1.2</file>
8963 </footnote> rather than quoting them in the copyright
8968 You should not use the copyright file as a general <file>README</file>
8969 file. If your package has such a file it should be
8970 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
8971 <file>README.Debian</file> or some other appropriate place.</p>
8975 <heading>Examples</heading>
8978 Any examples (configurations, source files, whatever),
8979 should be installed in a directory
8980 <file>/usr/share/doc/<var>package</var>/examples</file>. These
8981 files should not be referenced by any program: they're there
8982 for the benefit of the system administrator and users as
8983 documentation only. Architecture-specific example files
8984 should be installed in a directory
8985 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
8987 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
8988 latter directory itself may be a symbolic link to the
8993 If the purpose of a package is to provide examples, then the
8994 example files may be installed into
8995 <file>/usr/share/doc/<var>package</var></file>.
8999 <sect id="changelogs">
9000 <heading>Changelog files</heading>
9003 Packages that are not Debian-native must contain a
9004 compressed copy of the <file>debian/changelog</file> file from
9005 the Debian source tree in
9006 <file>/usr/share/doc/<var>package</var></file> with the name
9007 <file>changelog.Debian.gz</file>.
9011 If an upstream changelog is available, it should be accessible as
9012 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9013 plain text. If the upstream changelog is distributed in
9014 HTML, it should be made available in that form as
9015 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9016 and a plain text <file>changelog.gz</file> should be generated
9017 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9018 the upstream changelog files do not already conform to this
9019 naming convention, then this may be achieved either by
9020 renaming the files, or by adding a symbolic link, at the
9021 maintainer's discretion.<footnote>
9022 Rationale: People should not have to look in places for
9023 upstream changelogs merely because they are given
9024 different names or are distributed in HTML format.
9029 All of these files should be installed compressed using
9030 <tt>gzip -9</tt>, as they will become large with time even
9031 if they start out small.
9035 If the package has only one changelog which is used both as
9036 the Debian changelog and the upstream one because there is
9037 no separate upstream maintainer then that changelog should
9038 usually be installed as
9039 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9040 there is a separate upstream maintainer, but no upstream
9041 changelog, then the Debian changelog should still be called
9042 <file>changelog.Debian.gz</file>.
9046 For details about the format and contents of the Debian
9047 changelog file, please see <ref id="dpkgchangelog">.
9052 <appendix id="pkg-scope">
9053 <heading>Introduction and scope of these appendices</heading>
9056 These appendices are taken essentially verbatim from the
9057 now-deprecated Packaging Manual, version 3.2.1.0. They are
9058 the chapters which are likely to be of use to package
9059 maintainers and which have not already been included in the
9060 policy document itself. Most of these sections are very likely
9061 not relevant to policy; they should be treated as
9062 documentation for the packaging system. Please note that these
9063 appendices are included for convenience, and for historical
9064 reasons: they used to be part of policy package, and they have
9065 not yet been incorporated into dpkg documentation. However,
9066 they still have value, and hence they are presented here.
9070 They have not yet been checked to ensure that they are
9071 compatible with the contents of policy, and if there are any
9072 contradictions, the version in the main policy document takes
9073 precedence. The remaining chapters of the old Packaging
9074 Manual have also not been read in detail to ensure that there
9075 are not parts which have been left out. Both of these will be
9080 Certain parts of the Packaging manual were integrated into the
9081 Policy Manual proper, and removed from the appendices. Links
9082 have been placed from the old locations to the new ones.
9086 <prgn>dpkg</prgn> is a suite of programs for creating binary
9087 package files and installing and removing them on Unix
9089 <prgn>dpkg</prgn> is targeted primarily at Debian
9090 GNU/Linux, but may work on or be ported to other
9096 The binary packages are designed for the management of
9097 installed executable programs (usually compiled binaries) and
9098 their associated data, though source code examples and
9099 documentation are provided as part of some packages.</p>
9102 This manual describes the technical aspects of creating Debian
9103 binary packages (<file>.deb</file> files). It documents the
9104 behavior of the package management programs
9105 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9106 they interact with packages.</p>
9109 It also documents the interaction between
9110 <prgn>dselect</prgn>'s core and the access method scripts it
9111 uses to actually install the selected packages, and describes
9112 how to create a new access method.</p>
9115 This manual does not go into detail about the options and
9116 usage of the package building and installation tools. It
9117 should therefore be read in conjunction with those programs'
9122 The utility programs which are provided with <prgn>dpkg</prgn>
9123 for managing various system configuration and similar issues,
9124 such as <prgn>update-rc.d</prgn> and
9125 <prgn>install-info</prgn>, are not described in detail here -
9126 please see their man pages.
9130 It is assumed that the reader is reasonably familiar with the
9131 <prgn>dpkg</prgn> System Administrators' manual.
9132 Unfortunately this manual does not yet exist.
9136 The Debian version of the FSF's GNU hello program is provided
9137 as an example for people wishing to create Debian
9138 packages. The Debian <prgn>debmake</prgn> package is
9139 recommended as a very helpful tool in creating and maintaining
9140 Debian packages. However, while the tools and examples are
9141 helpful, they do not replace the need to read and follow the
9142 Policy and Programmer's Manual.</p>
9145 <appendix id="pkg-binarypkg">
9146 <heading>Binary packages (from old Packaging Manual)</heading>
9149 The binary package has two main sections. The first part
9150 consists of various control information files and scripts used
9151 by <prgn>dpkg</prgn> when installing and removing. See <ref
9152 id="pkg-controlarea">.
9156 The second part is an archive containing the files and
9157 directories to be installed.
9161 In the future binary packages may also contain other
9162 components, such as checksums and digital signatures. The
9163 format for the archive is described in full in the
9164 <file>deb(5)</file> man page.
9168 <sect id="pkg-bincreating"><heading>Creating package files -
9169 <prgn>dpkg-deb</prgn>
9173 All manipulation of binary package files is done by
9174 <prgn>dpkg-deb</prgn>; it's the only program that has
9175 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9176 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9177 will spot that the options requested are appropriate to
9178 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9183 In order to create a binary package you must make a
9184 directory tree which contains all the files and directories
9185 you want to have in the file system data part of the package.
9186 In Debian-format source packages this directory is usually
9187 <file>debian/tmp</file>, relative to the top of the package's
9192 They should have the locations (relative to the root of the
9193 directory tree you're constructing) ownerships and
9194 permissions which you want them to have on the system when
9199 With current versions of <prgn>dpkg</prgn> the uid/username
9200 and gid/groupname mappings for the users and groups being
9201 used should be the same on the system where the package is
9202 built and the one where it is installed.
9206 You need to add one special directory to the root of the
9207 miniature file system tree you're creating:
9208 <prgn>DEBIAN</prgn>. It should contain the control
9209 information files, notably the binary package control file
9210 (see <ref id="pkg-controlfile">).
9214 The <prgn>DEBIAN</prgn> directory will not appear in the
9215 file system archive of the package, and so won't be installed
9216 by <prgn>dpkg</prgn> when the package is installed.
9220 When you've prepared the package, you should invoke:
9222 dpkg --build <var>directory</var>
9227 This will build the package in
9228 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9229 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9230 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9235 See the man page <manref name="dpkg-deb" section="8"> for details of how
9236 to examine the contents of this newly-created file. You may find the
9237 output of following commands enlightening:
9239 dpkg-deb --info <var>filename</var>.deb
9240 dpkg-deb --contents <var>filename</var>.deb
9241 dpkg --contents <var>filename</var>.deb
9243 To view the copyright file for a package you could use this command:
9245 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - \*/copyright | pager
9250 <sect id="pkg-controlarea">
9251 <heading>Package control information files</heading>
9254 The control information portion of a binary package is a
9255 collection of files with names known to <prgn>dpkg</prgn>.
9256 It will treat the contents of these files specially - some
9257 of them contain information used by <prgn>dpkg</prgn> when
9258 installing or removing the package; others are scripts which
9259 the package maintainer wants <prgn>dpkg</prgn> to run.
9263 It is possible to put other files in the package control
9264 area, but this is not generally a good idea (though they
9265 will largely be ignored).
9269 Here is a brief list of the control info files supported by
9270 <prgn>dpkg</prgn> and a summary of what they're used for.
9275 <tag><tt>control</tt>
9278 This is the key description file used by
9279 <prgn>dpkg</prgn>. It specifies the package's name
9280 and version, gives its description for the user,
9281 states its relationships with other packages, and so
9282 forth. See <ref id="sourcecontrolfiles"> and
9283 <ref id="binarycontrolfiles">.
9287 It is usually generated automatically from information
9288 in the source package by the
9289 <prgn>dpkg-gencontrol</prgn> program, and with
9290 assistance from <prgn>dpkg-shlibdeps</prgn>.
9291 See <ref id="pkg-sourcetools">.
9295 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9300 These are executable files (usually scripts) which
9301 <prgn>dpkg</prgn> runs during installation, upgrade
9302 and removal of packages. They allow the package to
9303 deal with matters which are particular to that package
9304 or require more complicated processing than that
9305 provided by <prgn>dpkg</prgn>. Details of when and
9306 how they are called are in <ref id="maintainerscripts">.
9310 It is very important to make these scripts idempotent.
9311 See <ref id="idempotency">.
9315 The maintainer scripts are guaranteed to run with a
9316 controlling terminal and can interact with the user.
9317 See <ref id="controllingterminal">.
9321 <tag><tt>conffiles</tt>
9324 This file contains a list of configuration files which
9325 are to be handled automatically by <prgn>dpkg</prgn>
9326 (see <ref id="pkg-conffiles">). Note that not necessarily
9327 every configuration file should be listed here.
9330 <tag><tt>shlibs</tt>
9333 This file contains a list of the shared libraries
9334 supplied by the package, with dependency details for
9335 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9336 when it determines what dependencies are required in a
9337 package control file. The <tt>shlibs</tt> file format
9338 is described on <ref id="shlibs">.
9343 <sect id="pkg-controlfile">
9344 <heading>The main control information file: <tt>control</tt></heading>
9347 The most important control information file used by
9348 <prgn>dpkg</prgn> when it installs a package is
9349 <tt>control</tt>. It contains all the package's "vital
9354 The binary package control files of packages built from
9355 Debian sources are made by a special tool,
9356 <prgn>dpkg-gencontrol</prgn>, which reads
9357 <file>debian/control</file> and <file>debian/changelog</file> to
9358 find the information it needs. See <ref id="pkg-sourcepkg"> for
9363 The fields in binary package control files are listed in
9364 <ref id="binarycontrolfiles">.
9368 A description of the syntax of control files and the purpose
9369 of the fields is available in <ref id="controlfields">.
9374 <heading>Time Stamps</heading>
9377 See <ref id="timestamps">.
9382 <appendix id="pkg-sourcepkg">
9383 <heading>Source packages (from old Packaging Manual) </heading>
9386 The Debian binary packages in the distribution are generated
9387 from Debian sources, which are in a special format to assist
9388 the easy and automatic building of binaries.
9391 <sect id="pkg-sourcetools">
9392 <heading>Tools for processing source packages</heading>
9395 Various tools are provided for manipulating source packages;
9396 they pack and unpack sources and help build of binary
9397 packages and help manage the distribution of new versions.
9401 They are introduced and typical uses described here; see
9402 <manref name="dpkg-source" section="1"> for full
9403 documentation about their arguments and operation.
9407 For examples of how to construct a Debian source package,
9408 and how to use those utilities that are used by Debian
9409 source packages, please see the <prgn>hello</prgn> example
9413 <sect1 id="pkg-dpkg-source">
9415 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
9420 This program is frequently used by hand, and is also
9421 called from package-independent automated building scripts
9422 such as <prgn>dpkg-buildpackage</prgn>.
9426 To unpack a package it is typically invoked with
9428 dpkg-source -x <var>.../path/to/filename</var>.dsc
9433 with the <file><var>filename</var>.tar.gz</file> and
9434 <file><var>filename</var>.diff.gz</file> (if applicable) in
9435 the same directory. It unpacks into
9436 <file><var>package</var>-<var>version</var></file>, and if
9438 <file><var>package</var>-<var>version</var>.orig</file>, in
9439 the current directory.
9443 To create a packed source archive it is typically invoked:
9445 dpkg-source -b <var>package</var>-<var>version</var>
9450 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
9451 <file>.diff.gz</file> (if appropriate) in the current
9452 directory. <prgn>dpkg-source</prgn> does not clean the
9453 source tree first - this must be done separately if it is
9458 See also <ref id="pkg-sourcearchives">.</p>
9462 <sect1 id="pkg-dpkg-buildpackage">
9464 <prgn>dpkg-buildpackage</prgn> - overall package-building
9469 <prgn>dpkg-buildpackage</prgn> is a script which invokes
9470 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
9471 targets <tt>clean</tt>, <tt>build</tt> and
9472 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
9473 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
9474 source and binary package upload.
9478 It is usually invoked by hand from the top level of the
9479 built or unbuilt source directory. It may be invoked with
9480 no arguments; useful arguments include:
9481 <taglist compact="compact">
9482 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
9485 Do not sign the <tt>.changes</tt> file or the
9486 source package <tt>.dsc</tt> file, respectively.</p>
9488 <tag><tt>-p<var>sign-command</var></tt></tag>
9491 Invoke <var>sign-command</var> instead of finding
9492 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
9493 <var>sign-command</var> must behave just like
9494 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9496 <tag><tt>-r<var>root-command</var></tt></tag>
9499 When root privilege is required, invoke the command
9500 <var>root-command</var>. <var>root-command</var>
9501 should invoke its first argument as a command, from
9502 the <prgn>PATH</prgn> if necessary, and pass its
9503 second and subsequent arguments to the command it
9504 calls. If no <var>root-command</var> is supplied
9505 then <var>dpkg-buildpackage</var> will take no
9506 special action to gain root privilege, so that for
9507 most packages it will have to be invoked as root to
9510 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9513 Two types of binary-only build and upload - see
9514 <manref name="dpkg-source" section="1">.
9521 <sect1 id="pkg-dpkg-gencontrol">
9523 <prgn>dpkg-gencontrol</prgn> - generates binary package
9528 This program is usually called from <file>debian/rules</file>
9529 (see <ref id="pkg-sourcetree">) in the top level of the source
9534 This is usually done just before the files and directories in the
9535 temporary directory tree where the package is being built have their
9536 permissions and ownerships set and the package is constructed using
9537 <prgn>dpkg-deb/</prgn>
9539 This is so that the control file which is produced has
9540 the right permissions
9545 <prgn>dpkg-gencontrol</prgn> must be called after all the
9546 files which are to go into the package have been placed in
9547 the temporary build directory, so that its calculation of
9548 the installed size of a package is correct.
9552 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9553 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9554 variable substitutions created by
9555 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9560 For a package which generates only one binary package, and
9561 which builds it in <file>debian/tmp</file> relative to the top
9562 of the source package, it is usually sufficient to call
9563 <prgn>dpkg-gencontrol</prgn>.
9567 Sources which build several binaries will typically need
9570 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9571 </example> The <tt>-P</tt> tells
9572 <prgn>dpkg-gencontrol</prgn> that the package is being
9573 built in a non-default directory, and the <tt>-p</tt>
9574 tells it which package's control file should be generated.
9578 <prgn>dpkg-gencontrol</prgn> also adds information to the
9579 list of files in <file>debian/files</file>, for the benefit of
9580 (for example) a future invocation of
9581 <prgn>dpkg-genchanges</prgn>.</p>
9584 <sect1 id="pkg-dpkg-shlibdeps">
9586 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9591 This program is usually called from <file>debian/rules</file>
9592 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9593 id="pkg-sourcetree">), in the top level of the source tree.
9597 Its arguments are executables and shared libraries
9600 They may be specified either in the locations in the
9601 source tree where they are created or in the locations
9602 in the temporary build tree where they are installed
9603 prior to binary package creation.
9605 </footnote> for which shared library dependencies should
9606 be included in the binary package's control file.
9610 If some of the found shared libraries should only
9611 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9612 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9613 by using the <tt>-d<var>dependency-field</var></tt> option
9614 before those executable(s). (Each <tt>-d</tt> option
9615 takes effect until the next <tt>-d</tt>.)
9619 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9620 output control file to be modified. Instead by default it
9621 adds to the <file>debian/substvars</file> file variable
9622 settings like <tt>shlibs:Depends</tt>. These variable
9623 settings must be referenced in dependency fields in the
9624 appropriate per-binary-package sections of the source
9629 For example, a package that generates an essential part
9630 which requires dependencies, and optional parts that
9631 which only require a recommendation, would separate those
9632 two sets of dependencies into two different fields.<footnote>
9633 At the time of writing, an example for this was the
9634 <package/xmms/ package, with Depends used for the xmms
9635 executable, Recommends for the plug-ins and Suggests for
9636 even more optional features provided by unzip.
9638 It can say in its <file>debian/rules</file>:
9640 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9641 -dRecommends <var>optionalpart anotheroptionalpart</var>
9643 and then in its main control file <file>debian/control</file>:
9646 Depends: ${shlibs:Depends}
9647 Recommends: ${shlibs:Recommends}
9653 Sources which produce several binary packages with
9654 different shared library dependency requirements can use
9655 the <tt>-p<var>varnameprefix</var></tt> option to override
9656 the default <tt>shlibs:</tt> prefix (one invocation of
9657 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9658 They can thus produce several sets of dependency
9659 variables, each of the form
9660 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9661 which can be referred to in the appropriate parts of the
9662 binary package control files.
9667 <sect1 id="pkg-dpkg-distaddfile">
9669 <prgn>dpkg-distaddfile</prgn> - adds a file to
9670 <file>debian/files</file>
9674 Some packages' uploads need to include files other than
9675 the source and binary package files.
9679 <prgn>dpkg-distaddfile</prgn> adds a file to the
9680 <file>debian/files</file> file so that it will be included in
9681 the <file>.changes</file> file when
9682 <prgn>dpkg-genchanges</prgn> is run.
9686 It is usually invoked from the <tt>binary</tt> target of
9687 <file>debian/rules</file>:
9689 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9691 The <var>filename</var> is relative to the directory where
9692 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9693 is usually the directory above the top level of the source
9694 tree. The <file>debian/rules</file> target should put the
9695 file there just before or just after calling
9696 <prgn>dpkg-distaddfile</prgn>.
9700 The <var>section</var> and <var>priority</var> are passed
9701 unchanged into the resulting <file>.changes</file> file.
9706 <sect1 id="pkg-dpkg-genchanges">
9708 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9713 This program is usually called by package-independent
9714 automatic building scripts such as
9715 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9720 It is usually called in the top level of a built source
9721 tree, and when invoked with no arguments will print out a
9722 straightforward <file>.changes</file> file based on the
9723 information in the source package's changelog and control
9724 file and the binary and source packages which should have
9730 <sect1 id="pkg-dpkg-parsechangelog">
9732 <prgn>dpkg-parsechangelog</prgn> - produces parsed
9733 representation of a changelog
9737 This program is used internally by
9738 <prgn>dpkg-source</prgn> et al. It may also occasionally
9739 be useful in <file>debian/rules</file> and elsewhere. It
9740 parses a changelog, <file>debian/changelog</file> by default,
9741 and prints a control-file format representation of the
9742 information in it to standard output.
9746 <sect1 id="pkg-dpkg-architecture">
9748 <prgn>dpkg-architecture</prgn> - information about the build and
9753 This program can be used manually, but is also invoked by
9754 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9755 environment or make variables which specify the build and host
9756 architecture for the package building process.
9761 <sect id="pkg-sourcetree">
9762 <heading>The Debianised source tree</heading>
9765 The source archive scheme described later is intended to
9766 allow a Debianised source tree with some associated control
9767 information to be reproduced and transported easily. The
9768 Debianised source tree is a version of the original program
9769 with certain files added for the benefit of the
9770 Debianisation process, and with any other changes required
9771 made to the rest of the source code and installation
9776 The extra files created for Debian are in the subdirectory
9777 <file>debian</file> of the top level of the Debianised source
9778 tree. They are described below.
9781 <sect1 id="pkg-debianrules">
9782 <heading><file>debian/rules</file> - the main building script</heading>
9785 See <ref id="debianrules">.
9790 <sect1 id="pkg-dpkgchangelog">
9791 <heading><file>debian/changelog</file></heading>
9794 See <ref id="dpkgchangelog">.
9798 It is recommended that the entire changelog be encoded in the
9799 <url id="http://www.cis.ohio-state.edu/cgi-bin/rfc/rfc2279.html" name="UTF-8">
9801 <url id="http://www.unicode.org/"
9802 name="Unicode">.<footnote>
9804 I think it is fairly obvious that we need to
9805 eventually transition to UTF-8 for our package
9806 infrastructure; it is really the only sane char-set in
9807 an international environment. Now, we can't switch to
9808 using UTF-8 for package control fields and the like
9809 until dpkg has better support, but one thing we can
9810 start doing today is requesting that Debian changelogs
9811 are UTF-8 encoded. At some point in time, we can start
9812 requiring them to do so.
9815 Checking for non-UTF8 characters in a changelog is
9816 trivial. Dump the file through
9817 <example>iconv -f utf-8 -t ucs-4</example>
9818 discard the output, and check the return
9819 value. If there are any characters in the stream
9820 which are invalid UTF-8 sequences, iconv will exit
9821 with an error code; and this will be the case for the
9822 vast majority of other character sets.
9827 <sect2><heading>Defining alternative changelog formats
9831 It is possible to use a different format to the standard
9832 one, by providing a parser for the format you wish to
9837 In order to have <tt>dpkg-parsechangelog</tt> run your
9838 parser, you must include a line within the last 40 lines
9839 of your file matching the Perl regular expression:
9840 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9841 parentheses should be the name of the format. For
9842 example, you might say:
9844 @@@ changelog-format: joebloggs @@@
9846 Changelog format names are non-empty strings of alphanumerics.
9850 If such a line exists then <tt>dpkg-parsechangelog</tt>
9851 will look for the parser as
9852 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9854 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9855 it is an error for it not to find it, or for it not to
9856 be an executable program. The default changelog format
9857 is <tt>dpkg</tt>, and a parser for it is provided with
9858 the <tt>dpkg</tt> package.
9862 The parser will be invoked with the changelog open on
9863 standard input at the start of the file. It should read
9864 the file (it may seek if it wishes) to determine the
9865 information required and return the parsed information
9866 to standard output in the form of a series of control
9867 fields in the standard format. By default it should
9868 return information about only the most recent version in
9869 the changelog; it should accept a
9870 <tt>-v<var>version</var></tt> option to return changes
9871 information from all versions present <em>strictly
9872 after</em> <var>version</var>, and it should then be an
9873 error for <var>version</var> not to be present in the
9879 <list compact="compact">
9880 <item><qref id="f-Source"><tt>Source</tt></qref></item>
9881 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
9882 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
9883 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
9884 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
9885 <item><qref id="f-Date"><tt>Date</tt></qref></item>
9886 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
9891 If several versions are being returned (due to the use
9892 of <tt>-v</tt>), the urgency value should be of the
9893 highest urgency code listed at the start of any of the
9894 versions requested followed by the concatenated
9895 (space-separated) comments from all the versions
9896 requested; the maintainer, version, distribution and
9897 date should always be from the most recent version.
9901 For the format of the <tt>Changes</tt> field see
9902 <ref id="f-Changes">.
9906 If the changelog format which is being parsed always or
9907 almost always leaves a blank line between individual
9908 change notes these blank lines should be stripped out,
9909 so as to make the resulting output compact.
9913 If the changelog format does not contain date or package
9914 name information this information should be omitted from
9915 the output. The parser should not attempt to synthesize
9916 it or find it from other sources.
9920 If the changelog does not have the expected format the
9921 parser should exit with a nonzero exit status, rather
9922 than trying to muddle through and possibly generating
9927 A changelog parser may not interact with the user at
9933 <sect1 id="pkg-srcsubstvars">
9934 <heading><file>debian/substvars</file> and variable substitutions</heading>
9937 See <ref id="substvars">.
9943 <heading><file>debian/files</file></heading>
9946 See <ref id="debianfiles">.
9950 <sect1><heading><file>debian/tmp</file>
9954 This is the canonical temporary location for the
9955 construction of binary packages by the <tt>binary</tt>
9956 target. The directory <file>tmp</file> serves as the root of
9957 the file system tree as it is being constructed (for
9958 example, by using the package's upstream makefiles install
9959 targets and redirecting the output there), and it also
9960 contains the <tt>DEBIAN</tt> subdirectory. See <ref
9961 id="pkg-bincreating">.
9965 If several binary packages are generated from the same
9966 source tree it is usual to use several
9967 <file>debian/tmp<var>something</var></file> directories, for
9968 example <file>tmp-a</file> or <file>tmp-doc</file>.
9972 Whatever <file>tmp</file> directories are created and used by
9973 <tt>binary</tt> must of course be removed by the
9974 <tt>clean</tt> target.</p></sect1>
9978 <sect id="pkg-sourcearchives"><heading>Source packages as archives
9982 As it exists on the FTP site, a Debian source package
9983 consists of three related files. You must have the right
9984 versions of all three to be able to use them.
9989 <tag>Debian source control file - <tt>.dsc</tt></tag>
9991 This file is a control file used by <prgn>dpkg-source</prgn>
9992 to extract a source package.
9993 See <ref id="debiansourcecontrolfiles">.
9997 Original source archive -
9999 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10005 This is a compressed (with <tt>gzip -9</tt>)
10006 <prgn>tar</prgn> file containing the source code from
10007 the upstream authors of the program.
10012 Debianisation diff -
10014 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10020 This is a unified context diff (<tt>diff -u</tt>)
10021 giving the changes which are required to turn the
10022 original source into the Debian source. These changes
10023 may only include editing and creating plain files.
10024 The permissions of files, the targets of symbolic
10025 links and the characteristics of special files or
10026 pipes may not be changed and no files may be removed
10031 All the directories in the diff must exist, except the
10032 <file>debian</file> subdirectory of the top of the source
10033 tree, which will be created by
10034 <prgn>dpkg-source</prgn> if necessary when unpacking.
10038 The <prgn>dpkg-source</prgn> program will
10039 automatically make the <file>debian/rules</file> file
10040 executable (see below).</p></item>
10045 If there is no original source code - for example, if the
10046 package is specially prepared for Debian or the Debian
10047 maintainer is the same as the upstream maintainer - the
10048 format is slightly different: then there is no diff, and the
10050 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10051 and preferably contains a directory named
10052 <file><var>package</var>-<var>version</var></file>.
10057 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10060 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10061 Debian source package. However, if it is not available it
10062 is possible to unpack a Debian source archive as follows:
10063 <enumlist compact="compact">
10066 Untar the tarfile, which will create a <file>.orig</file>
10070 <p>Rename the <file>.orig</file> directory to
10071 <file><var>package</var>-<var>version</var></file>.</p>
10075 Create the subdirectory <file>debian</file> at the top of
10076 the source tree.</p>
10078 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10080 <item><p>Untar the tarfile again if you want a copy of the original
10081 source code alongside the Debianised version.</p>
10086 It is not possible to generate a valid Debian source archive
10087 without using <prgn>dpkg-source</prgn>. In particular,
10088 attempting to use <prgn>diff</prgn> directly to generate the
10089 <file>.diff.gz</file> file will not work.
10093 <heading>Restrictions on objects in source packages</heading>
10096 The source package may not contain any hard links
10098 This is not currently detected when building source
10099 packages, but only when extracting
10103 Hard links may be permitted at some point in the
10104 future, but would require a fair amount of
10106 </footnote>, device special files, sockets or setuid or
10109 Setgid directories are allowed.
10114 The source packaging tools manage the changes between the
10115 original and Debianised source using <prgn>diff</prgn> and
10116 <prgn>patch</prgn>. Turning the original source tree as
10117 included in the <file>.orig.tar.gz</file> into the debianised
10118 source must not involve any changes which cannot be
10119 handled by these tools. Problematic changes which cause
10120 <prgn>dpkg-source</prgn> to halt with an error when
10121 building the source package are:
10122 <list compact="compact">
10123 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10125 <item><p>Changing the targets of symbolic links.</p>
10127 <item><p>Creating directories, other than <file>debian</file>.</p>
10129 <item><p>Changes to the contents of binary files.</p></item>
10130 </list> Changes which cause <prgn>dpkg-source</prgn> to
10131 print a warning but continue anyway are:
10132 <list compact="compact">
10135 Removing files, directories or symlinks.
10137 Renaming a file is not treated specially - it is
10138 seen as the removal of the old file (which
10139 generates a warning, but is otherwise ignored),
10140 and the creation of the new one.
10146 Changed text files which are missing the usual final
10147 newline (either in the original or the modified
10152 Changes which are not represented, but which are not detected by
10153 <prgn>dpkg-source</prgn>, are:
10154 <list compact="compact">
10155 <item><p>Changing the permissions of files (other than
10156 <file>debian/rules</file>) and directories.</p></item>
10161 The <file>debian</file> directory and <file>debian/rules</file>
10162 are handled specially by <prgn>dpkg-source</prgn> - before
10163 applying the changes it will create the <file>debian</file>
10164 directory, and afterwards it will make
10165 <file>debian/rules</file> world-executable.
10171 <appendix id="pkg-controlfields">
10172 <heading>Control files and their fields (from old Packaging Manual)</heading>
10175 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10176 data in a common format, known as control files. Binary and
10177 source packages have control data as do the <file>.changes</file>
10178 files which control the installation of uploaded files, and
10179 <prgn>dpkg</prgn>'s internal databases are in a similar
10184 <heading>Syntax of control files</heading>
10187 See <ref id="controlsyntax">.
10191 It is important to note that there are several fields which
10192 are optional as far as <prgn>dpkg</prgn> and the related
10193 tools are concerned, but which must appear in every Debian
10194 package, or whose omission may cause problems.
10199 <heading>List of fields</heading>
10202 See <ref id="controlfieldslist">.
10206 This section now contains only the fields that didn't belong
10207 to the Policy manual.
10210 <sect1 id="pkg-f-Filename">
10211 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10214 These fields in <tt>Packages</tt> files give the
10215 filename(s) of (the parts of) a package in the
10216 distribution directories, relative to the root of the
10217 Debian hierarchy. If the package has been split into
10218 several parts the parts are all listed in order, separated
10223 <sect1 id="pkg-f-Size">
10224 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10227 These fields in <file>Packages</file> files give the size (in
10228 bytes, expressed in decimal) and MD5 checksum of the
10229 file(s) which make(s) up a binary package in the
10230 distribution. If the package is split into several parts
10231 the values for the parts are listed in order, separated by
10236 <sect1 id="pkg-f-Status">
10237 <heading><tt>Status</tt></heading>
10240 This field in <prgn>dpkg</prgn>'s status file records
10241 whether the user wants a package installed, removed or
10242 left alone, whether it is broken (requiring
10243 re-installation) or not and what its current state on the
10244 system is. Each of these pieces of information is a
10249 <sect1 id="pkg-f-Config-Version">
10250 <heading><tt>Config-Version</tt></heading>
10253 If a package is not installed or not configured, this
10254 field in <prgn>dpkg</prgn>'s status file records the last
10255 version of the package which was successfully
10260 <sect1 id="pkg-f-Conffiles">
10261 <heading><tt>Conffiles</tt></heading>
10264 This field in <prgn>dpkg</prgn>'s status file contains
10265 information about the automatically-managed configuration
10266 files held by a package. This field should <em>not</em>
10267 appear anywhere in a package!
10272 <heading>Obsolete fields</heading>
10275 These are still recognized by <prgn>dpkg</prgn> but should
10276 not appear anywhere any more.
10278 <taglist compact="compact">
10280 <tag><tt>Revision</tt></tag>
10281 <tag><tt>Package-Revision</tt></tag>
10282 <tag><tt>Package_Revision</tt></tag>
10284 The Debian revision part of the package version was
10285 at one point in a separate control file field. This
10286 field went through several names.
10289 <tag><tt>Recommended</tt></tag>
10290 <item>Old name for <tt>Recommends</tt>.</item>
10292 <tag><tt>Optional</tt></tag>
10293 <item>Old name for <tt>Suggests</tt>.</item>
10295 <tag><tt>Class</tt></tag>
10296 <item>Old name for <tt>Priority</tt>.</item>
10305 <appendix id="pkg-conffiles">
10306 <heading>Configuration file handling (from old Packaging Manual)</heading>
10309 <prgn>dpkg</prgn> can do a certain amount of automatic
10310 handling of package configuration files.
10314 Whether this mechanism is appropriate depends on a number of
10315 factors, but basically there are two approaches to any
10316 particular configuration file.
10320 The easy method is to ship a best-effort configuration in the
10321 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10322 handle updates. If the user is unlikely to want to edit the
10323 file, but you need them to be able to without losing their
10324 changes, and a new package with a changed version of the file
10325 is only released infrequently, this is a good approach.
10329 The hard method is to build the configuration file from
10330 scratch in the <prgn>postinst</prgn> script, and to take the
10331 responsibility for fixing any mistakes made in earlier
10332 versions of the package automatically. This will be
10333 appropriate if the file is likely to need to be different on
10337 <sect><heading>Automatic handling of configuration files by
10342 A package may contain a control area file called
10343 <tt>conffiles</tt>. This file should be a list of filenames
10344 of configuration files needing automatic handling, separated
10345 by newlines. The filenames should be absolute pathnames,
10346 and the files referred to should actually exist in the
10351 When a package is upgraded <prgn>dpkg</prgn> will process
10352 the configuration files during the configuration stage,
10353 shortly before it runs the package's <prgn>postinst</prgn>
10358 For each file it checks to see whether the version of the
10359 file included in the package is the same as the one that was
10360 included in the last version of the package (the one that is
10361 being upgraded from); it also compares the version currently
10362 installed on the system with the one shipped with the last
10367 If neither the user nor the package maintainer has changed
10368 the file, it is left alone. If one or the other has changed
10369 their version, then the changed version is preferred - i.e.,
10370 if the user edits their file, but the package maintainer
10371 doesn't ship a different version, the user's changes will
10372 stay, silently, but if the maintainer ships a new version
10373 and the user hasn't edited it the new version will be
10374 installed (with an informative message). If both have
10375 changed their version the user is prompted about the problem
10376 and must resolve the differences themselves.
10380 The comparisons are done by calculating the MD5 message
10381 digests of the files, and storing the MD5 of the file as it
10382 was included in the most recent version of the package.
10386 When a package is installed for the first time
10387 <prgn>dpkg</prgn> will install the file that comes with it,
10388 unless that would mean overwriting a file already on the
10393 However, note that <prgn>dpkg</prgn> will <em>not</em>
10394 replace a conffile that was removed by the user (or by a
10395 script). This is necessary because with some programs a
10396 missing file produces an effect hard or impossible to
10397 achieve in another way, so that a missing file needs to be
10398 kept that way if the user did it.
10402 Note that a package should <em>not</em> modify a
10403 <prgn>dpkg</prgn>-handled conffile in its maintainer
10404 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10405 the user confusing and possibly dangerous options for
10406 conffile update when the package is upgraded.</p>
10409 <sect><heading>Fully-featured maintainer script configuration
10414 For files which contain site-specific information such as
10415 the hostname and networking details and so forth, it is
10416 better to create the file in the package's
10417 <prgn>postinst</prgn> script.
10421 This will typically involve examining the state of the rest
10422 of the system to determine values and other information, and
10423 may involve prompting the user for some information which
10424 can't be obtained some other way.
10428 When using this method there are a couple of important
10429 issues which should be considered:
10433 If you discover a bug in the program which generates the
10434 configuration file, or if the format of the file changes
10435 from one version to the next, you will have to arrange for
10436 the postinst script to do something sensible - usually this
10437 will mean editing the installed configuration file to remove
10438 the problem or change the syntax. You will have to do this
10439 very carefully, since the user may have changed the file,
10440 perhaps to fix the very problem that your script is trying
10441 to deal with - you will have to detect these situations and
10442 deal with them correctly.
10446 If you do go down this route it's probably a good idea to
10447 make the program that generates the configuration file(s) a
10448 separate program in <file>/usr/sbin</file>, by convention called
10449 <file><var>package</var>config</file> and then run that if
10450 appropriate from the post-installation script. The
10451 <tt><var>package</var>config</tt> program should not
10452 unquestioningly overwrite an existing configuration - if its
10453 mode of operation is geared towards setting up a package for
10454 the first time (rather than any arbitrary reconfiguration
10455 later) you should have it check whether the configuration
10456 already exists, and require a <tt>--force</tt> flag to
10457 overwrite it.</p></sect>
10460 <appendix id="pkg-alternatives"><heading>Alternative versions of
10461 an interface - <prgn>update-alternatives</prgn> (from old
10466 When several packages all provide different versions of the
10467 same program or file it is useful to have the system select a
10468 default, but to allow the system administrator to change it
10469 and have their decisions respected.
10473 For example, there are several versions of the <prgn>vi</prgn>
10474 editor, and there is no reason to prevent all of them from
10475 being installed at once, each under their own name
10476 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10477 Nevertheless it is desirable to have the name <tt>vi</tt>
10478 refer to something, at least by default.
10482 If all the packages involved cooperate, this can be done with
10483 <prgn>update-alternatives</prgn>.
10487 Each package provides its own version under its own name, and
10488 calls <prgn>update-alternatives</prgn> in its postinst to
10489 register its version (and again in its prerm to deregister
10494 See the man page <manref name="update-alternatives"
10495 section="8"> for details.
10499 If <prgn>update-alternatives</prgn> does not seem appropriate
10500 you may wish to consider using diversions instead.</p>
10503 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10504 package's version of a file (from old Packaging Manual)
10508 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10509 when it reinstalls the package it belongs to, and to have it
10510 put the file from the package somewhere else instead.
10514 This can be used locally to override a package's version of a
10515 file, or by one package to override another's version (or
10516 provide a wrapper for it).
10520 Before deciding to use a diversion, read <ref
10521 id="pkg-alternatives"> to see if you really want a diversion
10522 rather than several alternative versions of a program.
10526 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10527 and updated by a special program <prgn>dpkg-divert</prgn>.
10528 Please see <manref name="dpkg-divert" section="8"> for full
10529 details of its operation.
10533 When a package wishes to divert a file from another, it should
10534 call <prgn>dpkg-divert</prgn> in its preinst to add the
10535 diversion and rename the existing file. For example,
10536 supposing that a <prgn>smailwrapper</prgn> package wishes to
10537 install a wrapper around <file>/usr/sbin/smail</file>:
10539 if [ install = "$1" ]; then
10540 dpkg-divert --package smailwrapper --add --rename \
10541 --divert /usr/sbin/smail.real /usr/sbin/smail
10543 </example> Testing <tt>$1</tt> is necessary so that the script
10544 doesn't try to add the diversion again when
10545 <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
10546 smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
10547 copy of <file>/usr/sbin/smail</file> can bypass the diversion and
10548 get installed as the true version.
10552 The postrm has to do the reverse:
10554 if [ remove = "$1" ]; then
10555 dpkg-divert --package smailwrapper --remove --rename \
10556 --divert /usr/sbin/smail.real /usr/sbin/smail
10562 Do not attempt to divert a file which is vitally important for
10563 the system's operation - when using <prgn>dpkg-divert</prgn>
10564 there is a time, after it has been diverted but before
10565 <prgn>dpkg</prgn> has installed the new version, when the file
10566 does not exist.</p>
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