1 <!doctype debiandoc system [
2 <!-- include version information so we don't have to hard code it
3 within the document -->
4 <!entity % versiondata SYSTEM "version.ent"> %versiondata;
10 <title>Debian Policy Manual</title>
11 <author><qref id="authors">The Debian Policy Mailing List</qref></author>
12 <version>version &version;, &date;</version>
15 This manual describes the policy requirements for the Debian
16 GNU/Linux distribution. This includes the structure and
17 contents of the Debian archive and several design issues of
18 the operating system, as well as technical requirements that
19 each package must satisfy to be included in the distribution.
24 Copyright © 1996,1997,1998 Ian Jackson
25 and Christian Schwarz.
28 This manual is free software; you may redistribute it and/or
29 modify it under the terms of the GNU General Public License
30 as published by the Free Software Foundation; either version
31 2, or (at your option) any later version.
35 This is distributed in the hope that it will be useful, but
36 <em>without any warranty</em>; without even the implied
37 warranty of merchantability or fitness for a particular
38 purpose. See the GNU General Public License for more
43 A copy of the GNU General Public License is available as
44 <file>/usr/share/common-licenses/GPL</file> in the Debian GNU/Linux
45 distribution or on the World Wide Web at
46 <url id="http://www.gnu.org/copyleft/gpl.html"
47 name="the GNU General Public Licence">. You can also
48 obtain it by writing to the Free Software Foundation, Inc.,
49 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
57 <heading>About this manual</heading>
59 <heading>Scope</heading>
61 This manual describes the policy requirements for the Debian
62 GNU/Linux distribution. This includes the structure and
63 contents of the Debian archive and several design issues of the
64 operating system, as well as technical requirements that
65 each package must satisfy to be included in the
70 This manual also describes Debian policy as it relates to
71 creating Debian packages. It is not a tutorial on how to build
72 packages, nor is it exhaustive where it comes to describing
73 the behavior of the packaging system. Instead, this manual
74 attempts to define the interface to the package management
75 system that the developers have to be conversant with.<footnote>
76 Informally, the criteria used for inclusion is that the
77 material meet one of the following requirements:
78 <taglist compact="compact">
79 <tag>Standard interfaces</tag>
81 The material presented represents an interface to
82 the packaging system that is mandated for use, and
83 is used by, a significant number of packages, and
84 therefore should not be changed without peer
85 review. Package maintainers can then rely on this
86 interfaces not changing, and the package
87 management software authors need to ensure
88 compatibility with these interface
89 definitions. (Control file and changelog file
90 formats are examples.)
92 <tag>Chosen Convention</tag>
94 If there are a number of technically viable choices
95 that can be made, but one needs to select one of
96 these options for inter-operability. The version
97 number format is one example.
100 Please note that these are not mutually exclusive;
101 selected conventions often become parts of standard
107 The footnotes present in this manual are
108 merely informative, and are not part of Debian policy itself.
112 The appendices to this manual are not necessarily normative,
113 either. Please see <ref id="pkg-scope"> for more information.
117 In the normative part of this manual,
118 the words <em>must</em>, <em>should</em> and
119 <em>may</em>, and the adjectives <em>required</em>,
120 <em>recommended</em> and <em>optional</em>, are used to
121 distinguish the significance of the various guidelines in
122 this policy document. Packages that do not conform to the
123 guidelines denoted by <em>must</em> (or <em>required</em>)
124 will generally not be considered acceptable for the Debian
125 distribution. Non-conformance with guidelines denoted by
126 <em>should</em> (or <em>recommended</em>) will generally be
127 considered a bug, but will not necessarily render a package
128 unsuitable for distribution. Guidelines denoted by
129 <em>may</em> (or <em>optional</em>) are truly optional and
130 adherence is left to the maintainer's discretion.
134 These classifications are roughly equivalent to the bug
135 severities <em>serious</em> (for <em>must</em> or
136 <em>required</em> directive violations), <em>minor</em>,
137 <em>normal</em> or <em>important</em>
138 (for <em>should</em> or <em>recommended</em> directive
139 violations) and <em>wishlist</em> (for <em>optional</em>
142 Compare RFC 2119. Note, however, that these words are
143 used in a different way in this document.
148 Much of the information presented in this manual will be
149 useful even when building a package which is to be
150 distributed in some other way or is intended for local use
156 <heading>New versions of this document</heading>
159 This manual is distributed via the Debian package
160 <package><url name="debian-policy"
161 id="http://packages.debian.org/debian-policy"></package>
162 (<httpsite>packages.debian.org</httpsite>
163 <httppath>/debian-policy</httppath>).
167 The current version of this document is also available from
168 the Debian web mirrors at
169 <tt><url name="/doc/debian-policy/"
170 id="http://www.debian.org/doc/debian-policy/"></tt>.
172 <httpsite>www.debian.org</httpsite>
173 <httppath>/doc/debian-policy/</httppath>)
174 Also available from the same directory are several other
175 formats: <file>policy.html.tar.gz</file>
176 (<httppath>/doc/debian-policy/policy.html.tar.gz</httppath>),
177 <file>policy.pdf.gz</file>
178 (<httppath>/doc/debian-policy/policy.pdf.gz</httppath>)
179 and <file>policy.ps.gz</file>
180 (<httppath>/doc/debian-policy/policy.ps.gz</httppath>).
184 The <package>debian-policy</package> package also includes the file
185 <file>upgrading-checklist.txt.gz</file> which indicates policy
186 changes between versions of this document.
191 <heading>Authors and Maintainers</heading>
194 Originally called "Debian GNU/Linux Policy Manual", this
195 manual was initially written in 1996 by Ian Jackson.
196 It was revised on November 27th, 1996 by David A. Morris.
197 Christian Schwarz added new sections on March 15th, 1997,
198 and reworked/restructured it in April-July 1997.
199 Christoph Lameter contributed the "Web Standard".
200 Julian Gilbey largely restructured it in 2001.
204 Since September 1998, the responsibility for the contents of
205 this document lies on the <url name="debian-policy mailing list"
206 id="mailto:debian-policy@lists.debian.org">. Proposals
207 are discussed there and inserted into policy after a certain
208 consensus is established.
209 <!-- insert shameless policy-process plug here eventually -->
210 The actual editing is done by a group of maintainers that have
211 no editorial powers. These are the current maintainers:
214 <item>Julian Gilbey</item>
215 <item>Branden Robinson</item>
216 <item>Josip Rodin</item>
217 <item>Manoj Srivastava</item>
222 While the authors of this document have tried hard to avoid
223 typos and other errors, these do still occur. If you discover
224 an error in this manual or if you want to give any
225 comments, suggestions, or criticisms please send an email to
226 the Debian Policy List,
227 <email>debian-policy@lists.debian.org</email>, or submit a
228 bug report against the <tt>debian-policy</tt> package.
232 Please do not try to reach the individual authors or maintainers
233 of the Policy Manual regarding changes to the Policy.
238 <heading>Related documents</heading>
241 There are several other documents other than this Policy Manual
242 that are necessary to fully understand some Debian policies and
247 The external "sub-policy" documents are referred to in:
248 <list compact="compact">
249 <item><ref id="fhs"></item>
250 <item><ref id="virtual_pkg"></item>
251 <item><ref id="menus"></item>
252 <item><ref id="mime"></item>
253 <item><ref id="perl"></item>
254 <item><ref id="maintscriptprompt"></item>
255 <item><ref id="emacs"></item>
260 In addition to those, which carry the weight of policy, there
261 is the Debian Developer's Reference. This document describes
262 procedures and resources for Debian developers, but it is
263 <em>not</em> normative; rather, it includes things that don't
264 belong in the Policy, such as best practices for developers.
268 The Developer's Reference is available in the
269 <package>developers-reference</package> package.
270 It's also available from the Debian web mirrors at
271 <tt><url name="/doc/developers-reference/"
272 id="http://www.debian.org/doc/developers-reference/"></tt>.
280 <heading>The Debian Archive</heading>
283 The Debian GNU/Linux system is maintained and distributed as a
284 collection of <em>packages</em>. Since there are so many of
285 them (currently well over 15000), they are split into
286 <em>sections</em> and given <em>priorities</em> to simplify
287 the handling of them.
291 The effort of the Debian project is to build a free operating
292 system, but not every package we want to make accessible is
293 <em>free</em> in our sense (see the Debian Free Software
294 Guidelines, below), or may be imported/exported without
295 restrictions. Thus, the archive is split into the distribution
296 areas or categories based on their licenses and other restrictions.
300 The aims of this are:
302 <list compact="compact">
303 <item>to allow us to make as much software available as we can</item>
304 <item>to allow us to encourage everyone to write free software,
306 <item>to allow us to make it easy for people to produce
307 CD-ROMs of our system without violating any licenses,
308 import/export restrictions, or any other laws.</item>
313 The <em>main</em> category forms the
314 <em>Debian GNU/Linux distribution</em>.
318 Packages in the other distribution areas (<tt>contrib</tt>,
319 <tt>non-free</tt>) are not considered to be part of the Debian
320 distribution, although we support their use and provide
321 infrastructure for them (such as our bug-tracking system and
322 mailing lists). This Debian Policy Manual applies to these
327 <heading>The Debian Free Software Guidelines</heading>
329 The Debian Free Software Guidelines (DFSG) form our
330 definition of "free software". These are:
332 <tag>Free Redistribution
335 The license of a Debian component may not restrict any
336 party from selling or giving away the software as a
337 component of an aggregate software distribution
338 containing programs from several different
339 sources. The license may not require a royalty or
340 other fee for such sale.
345 The program must include source code, and must allow
346 distribution in source code as well as compiled form.
351 The license must allow modifications and derived
352 works, and must allow them to be distributed under the
353 same terms as the license of the original software.
355 <tag>Integrity of The Author's Source Code
358 The license may restrict source-code from being
359 distributed in modified form <em>only</em> if the
360 license allows the distribution of "patch files"
361 with the source code for the purpose of modifying the
362 program at build time. The license must explicitly
363 permit distribution of software built from modified
364 source code. The license may require derived works to
365 carry a different name or version number from the
366 original software. (This is a compromise. The Debian
367 Project encourages all authors to not restrict any
368 files, source or binary, from being modified.)
370 <tag>No Discrimination Against Persons or Groups
373 The license must not discriminate against any person
376 <tag>No Discrimination Against Fields of Endeavor
379 The license must not restrict anyone from making use
380 of the program in a specific field of endeavor. For
381 example, it may not restrict the program from being
382 used in a business, or from being used for genetic
385 <tag>Distribution of License
388 The rights attached to the program must apply to all
389 to whom the program is redistributed without the need
390 for execution of an additional license by those
393 <tag>License Must Not Be Specific to Debian
396 The rights attached to the program must not depend on
397 the program's being part of a Debian system. If the
398 program is extracted from Debian and used or
399 distributed without Debian but otherwise within the
400 terms of the program's license, all parties to whom
401 the program is redistributed must have the same
402 rights as those that are granted in conjunction with
405 <tag>License Must Not Contaminate Other Software
408 The license must not place restrictions on other
409 software that is distributed along with the licensed
410 software. For example, the license must not insist
411 that all other programs distributed on the same medium
412 must be free software.
414 <tag>Example Licenses
417 The "GPL," "BSD," and "Artistic" licenses are examples of
418 licenses that we consider <em>free</em>.
425 <heading>Categories</heading>
428 <heading>The main category</heading>
431 Every package in <em>main</em> must comply with the DFSG
432 (Debian Free Software Guidelines).
436 In addition, the packages in <em>main</em>
437 <list compact="compact">
439 must not require a package outside of <em>main</em>
440 for compilation or execution (thus, the package must
441 not declare a "Depends", "Recommends", or
442 "Build-Depends" relationship on a non-<em>main</em>
446 must not be so buggy that we refuse to support them,
450 must meet all policy requirements presented in this
459 <heading>The contrib category</heading>
462 Every package in <em>contrib</em> must comply with the DFSG.
466 In addition, the packages in <em>contrib</em>
467 <list compact="compact">
469 must not be so buggy that we refuse to support them,
473 must meet all policy requirements presented in this
481 Examples of packages which would be included in
482 <em>contrib</em> are:
483 <list compact="compact">
485 free packages which require <em>contrib</em>,
486 <em>non-free</em> packages or packages which are not
487 in our archive at all for compilation or execution,
491 wrapper packages or other sorts of free accessories for
498 <sect1 id="non-free">
499 <heading>The non-free category</heading>
502 Packages must be placed in <em>non-free</em> if they are
503 not compliant with the DFSG or are encumbered by patents
504 or other legal issues that make their distribution
509 In addition, the packages in <em>non-free</em>
510 <list compact="compact">
512 must not be so buggy that we refuse to support them,
516 must meet all policy requirements presented in this
517 manual that it is possible for them to meet.
519 It is possible that there are policy
520 requirements which the package is unable to
521 meet, for example, if the source is
522 unavailable. These situations will need to be
523 handled on a case-by-case basis.
532 <sect id="pkgcopyright">
533 <heading>Copyright considerations</heading>
536 Every package must be accompanied by a verbatim copy of
537 its copyright and distribution license in the file
538 <file>/usr/share/doc/<var>package</var>/copyright</file>
539 (see <ref id="copyrightfile"> for further details).
543 We reserve the right to restrict files from being included
544 anywhere in our archives if
545 <list compact="compact">
547 their use or distribution would break a law,
550 there is an ethical conflict in their distribution or
554 we would have to sign a license for them, or
557 their distribution would conflict with other project
564 Programs whose authors encourage the user to make
565 donations are fine for the main distribution, provided
566 that the authors do not claim that not donating is
567 immoral, unethical, illegal or something similar; in such
568 a case they must go in <em>non-free</em>.
572 Packages whose copyright permission notices (or patent
573 problems) do not even allow redistribution of binaries
574 only, and where no special permission has been obtained,
575 must not be placed on the Debian FTP site and its mirrors
580 Note that under international copyright law (this applies
581 in the United States, too), <em>no</em> distribution or
582 modification of a work is allowed without an explicit
583 notice saying so. Therefore a program without a copyright
584 notice <em>is</em> copyrighted and you may not do anything
585 to it without risking being sued! Likewise if a program
586 has a copyright notice but no statement saying what is
587 permitted then nothing is permitted.
591 Many authors are unaware of the problems that restrictive
592 copyrights (or lack of copyright notices) can cause for
593 the users of their supposedly-free software. It is often
594 worthwhile contacting such authors diplomatically to ask
595 them to modify their license terms. However, this can be a
596 politically difficult thing to do and you should ask for
597 advice on the <tt>debian-legal</tt> mailing list first, as
602 When in doubt about a copyright, send mail to
603 <email>debian-legal@lists.debian.org</email>. Be prepared
604 to provide us with the copyright statement. Software
605 covered by the GPL, public domain software and BSD-like
606 copyrights are safe; be wary of the phrases "commercial
607 use prohibited" and "distribution restricted".
611 <sect id="subsections">
612 <heading>Sections</heading>
615 The packages in the categories <em>main</em>,
616 <em>contrib</em> and <em>non-free</em> are grouped further
617 into <em>sections</em> to simplify handling.
621 The category and section for each package should be
622 specified in the package's <tt>Section</tt> control record
623 (see <ref id="f-Section">). However, the maintainer of the
624 Debian archive may override this selection to ensure the
625 consistency of the Debian distribution. The
626 <tt>Section</tt> field should be of the form:
627 <list compact="compact">
629 <em>section</em> if the package is in the
630 <em>main</em> category,
633 <em>segment/section</em> if the package is in
634 the <em>contrib</em> or <em>non-free</em>
641 The Debian archive maintainers provide the authoritative
642 list of sections. At present, they are:
643 <em>admin</em>, <em>comm</em>,
644 <em>devel</em>, <em>doc</em>,
645 <em>editors</em>, <em>electronics</em>, <em>embedded</em>,
646 <em>games</em>, <em>gnome</em>, <em>graphics</em>,
647 <em>hamradio</em>, <em>interpreters</em>, <em>kde</em>,
648 <em>libs</em>, <em>libdevel</em>, <em>mail</em>,
649 <em>math</em>, <em>misc</em>, <em>net</em>, <em>news</em>,
651 <em>otherosfs</em>, <em>perl</em>, <em>python</em>,
652 <em>science</em>, <em>shells</em>,
653 <em>sound</em>, <em>tex</em>, <em>text</em>,
654 <em>utils</em>, <em>web</em>, <em>x11</em>.
658 <sect id="priorities">
659 <heading>Priorities</heading>
662 Each package should have a <em>priority</em> value, which is
663 included in the package's <em>control record</em>
664 (see <ref id="f-Priority">).
665 This information is used by the Debian package management tools to
666 separate high-priority packages from less-important packages.
670 The following <em>priority levels</em> are recognized by the
671 Debian package management tools.
673 <tag><tt>required</tt></tag>
675 Packages which are necessary for the proper
676 functioning of the system (usually, this means that
677 dpkg functionality depends on these packages).
678 Removing a <tt>required</tt> package may cause your
679 system to become totally broken and you may not even
680 be able to use <prgn>dpkg</prgn> to put things back,
681 so only do so if you know what you are doing. Systems
682 with only the <tt>required</tt> packages are probably
683 unusable, but they do have enough functionality to
684 allow the sysadmin to boot and install more software.
686 <tag><tt>important</tt></tag>
688 Important programs, including those which one would
689 expect to find on any Unix-like system. If the
690 expectation is that an experienced Unix person who
691 found it missing would say "What on earth is going on,
692 where is <prgn>foo</prgn>?", it must be an
693 <tt>important</tt> package.<footnote>
694 This is an important criterion because we are
695 trying to produce, amongst other things, a free
698 Other packages without which the system will not run
699 well or be usable must also have priority
700 <tt>important</tt>. This does
701 <em>not</em> include Emacs, the X Window System, TeX
702 or any other large applications. The
703 <tt>important</tt> packages are just a bare minimum of
704 commonly-expected and necessary tools.
706 <tag><tt>standard</tt></tag>
708 These packages provide a reasonably small but not too
709 limited character-mode system. This is what will be
710 installed by default if the user doesn't select anything
711 else. It doesn't include many large applications.
713 <tag><tt>optional</tt></tag>
715 (In a sense everything that isn't required is
716 optional, but that's not what is meant here.) This is
717 all the software that you might reasonably want to
718 install if you didn't know what it was and don't have
719 specialized requirements. This is a much larger system
720 and includes the X Window System, a full TeX
721 distribution, and many applications. Note that
722 optional packages should not conflict with each other.
724 <tag><tt>extra</tt></tag>
726 This contains all packages that conflict with others
727 with required, important, standard or optional
728 priorities, or are only likely to be useful if you
729 already know what they are or have specialized
736 Packages must not depend on packages with lower priority
737 values (excluding build-time dependencies). In order to
738 ensure this, the priorities of one or more packages may need
747 <heading>Binary packages</heading>
750 The Debian GNU/Linux distribution is based on the Debian
751 package management system, called <prgn>dpkg</prgn>. Thus,
752 all packages in the Debian distribution must be provided
753 in the <tt>.deb</tt> file format.
757 <heading>The package name</heading>
760 Every package must have a name that's unique within the Debian
765 The package name is included in the control field
766 <tt>Package</tt>, the format of which is described
767 in <ref id="f-Package">.
768 The package name is also included as a part of the file name
769 of the <tt>.deb</tt> file.
774 <heading>The version of a package</heading>
777 Every package has a version number recorded in its
778 <tt>Version</tt> control file field, described in
779 <ref id="f-Version">.
783 The package management system imposes an ordering on version
784 numbers, so that it can tell whether packages are being up- or
785 downgraded and so that package system front end applications
786 can tell whether a package it finds available is newer than
787 the one installed on the system. The version number format
788 has the most significant parts (as far as comparison is
789 concerned) at the beginning.
793 If an upstream package has problematic version numbers they
794 should be converted to a sane form for use in the
795 <tt>Version</tt> field.
799 <heading>Version numbers based on dates</heading>
802 In general, Debian packages should use the same version
803 numbers as the upstream sources.
807 However, in some cases where the upstream version number is
808 based on a date (e.g., a development "snapshot" release) the
809 package management system cannot handle these version
810 numbers without epochs. For example, dpkg will consider
811 "96May01" to be greater than "96Dec24".
815 To prevent having to use epochs for every new upstream
816 version, the date based portion of the version number
817 should be changed to the following format in such cases:
818 "19960501", "19961224". It is up to the maintainer whether
819 they want to bother the upstream maintainer to change
820 the version numbers upstream, too.
824 Note that other version formats based on dates which are
825 parsed correctly by the package management system should
826 <em>not</em> be changed.
830 Native Debian packages (i.e., packages which have been
831 written especially for Debian) whose version numbers include
832 dates should always use the "YYYYMMDD" format.
839 <heading>The maintainer of a package</heading>
842 Every package must have a Debian maintainer (the
843 maintainer may be one person or a group of people
844 reachable from a common email address, such as a mailing
845 list). The maintainer is responsible for ensuring that
846 the package is placed in the appropriate distributions.
850 The maintainer must be specified in the
851 <tt>Maintainer</tt> control field with their correct name
852 and a working email address. If one person maintains
853 several packages, they should try to avoid having
854 different forms of their name and email address in
855 the <tt>Maintainer</tt> fields of those packages.
859 The format of the <tt>Maintainer</tt> control field is
860 described in <ref id="f-Maintainer">.
864 If the maintainer of a package quits from the Debian
865 project, "Debian QA Group"
866 <email>packages@qa.debian.org</email> takes over the
867 maintainer-ship of the package until someone else
868 volunteers for that task. These packages are called
869 <em>orphaned packages</em>.<footnote>
870 The detailed procedure for doing this gracefully can
871 be found in the Debian Developer's Reference,
872 see <ref id="related">.
877 <sect id="descriptions">
878 <heading>The description of a package</heading>
881 Every Debian package must have an extended description
882 stored in the appropriate field of the control record.
883 The technical information about the format of the
884 <tt>Description</tt> field is in <ref id="f-Description">.
888 The description should describe the package (the program) to a
889 user (system administrator) who has never met it before so that
890 they have enough information to decide whether they want to
891 install it. This description should not just be copied verbatim
892 from the program's documentation.
896 Put important information first, both in the synopsis and
897 extended description. Sometimes only the first part of the
898 synopsis or of the description will be displayed. You can
899 assume that there will usually be a way to see the whole
900 extended description.
904 The description should also give information about the
905 significant dependencies and conflicts between this package
906 and others, so that the user knows why these dependencies and
907 conflicts have been declared.
911 Instructions for configuring or using the package should
912 not be included (that is what installation scripts,
913 manual pages, info files, etc., are for). Copyright
914 statements and other administrivia should not be included
915 either (that is what the copyright file is for).
918 <sect1 id="synopsis"><heading>The single line synopsis</heading>
921 The single line synopsis should be kept brief - certainly
926 Do not include the package name in the synopsis line. The
927 display software knows how to display this already, and you
928 do not need to state it. Remember that in many situations
929 the user may only see the synopsis line - make it as
930 informative as you can.
935 <sect1 id="extendeddesc"><heading>The extended description</heading>
938 Do not try to continue the single line synopsis into the
939 extended description. This will not work correctly when
940 the full description is displayed, and makes no sense
941 where only the summary (the single line synopsis) is
946 The extended description should describe what the package
947 does and how it relates to the rest of the system (in terms
948 of, for example, which subsystem it is which part of).
952 The description field needs to make sense to anyone, even
953 people who have no idea about any of the things the
954 package deals with.<footnote>
955 The blurb that comes with a program in its
956 announcements and/or <prgn>README</prgn> files is
957 rarely suitable for use in a description. It is
958 usually aimed at people who are already in the
959 community where the package is used.
968 <heading>Dependencies</heading>
971 Every package must specify the dependency information
972 about other packages that are required for the first to
977 For example, a dependency entry must be provided for any
978 shared libraries required by a dynamically-linked executable
983 Packages are not required to declare any dependencies they
984 have on other packages which are marked <tt>Essential</tt>
985 (see below), and should not do so unless they depend on a
986 particular version of that package.<footnote>
988 Essential is defined as the minimal set of functionality
989 that must be available and usable on the system even
990 when packages are in an unconfigured (but unpacked)
991 state. This is needed to avoid unresolvable dependency
992 loops on upgrade. If packages add unnecessary
993 dependencies on packages in this set, the chances that
994 there <strong>will</strong> be an unresolvable
995 dependency loop caused by forcing these Essential
996 packages to be configured first before they need to be
997 is greatly increased. It also increases the chances
998 that frontends will be unable to
999 <strong>calculate</strong> an upgrade path, even if one
1003 Also, it's pretty unlikely that functionality from
1004 Essential shall ever be removed (which is one reason why
1005 care must be taken before adding to the Essential
1006 packages set), but <em>packages</em> have been removed
1007 from the Essential set when the functionality moved to a
1008 different package. So depending on these packages
1009 <em>just in case</em> they stop being essential does way
1010 more harm than good.
1016 Sometimes, a package requires another package to be installed
1017 <em>and</em> configured before it can be installed. In this
1018 case, you must specify a <tt>Pre-Depends</tt> entry for
1023 You should not specify a <tt>Pre-Depends</tt> entry for a
1024 package before this has been discussed on the
1025 <tt>debian-devel</tt> mailing list and a consensus about
1026 doing that has been reached.
1030 The format of the package interrelationship control fields is
1031 described in <ref id="relationships">.
1035 <sect id="virtual_pkg">
1036 <heading>Virtual packages</heading>
1039 Sometimes, there are several packages which offer
1040 more-or-less the same functionality. In this case, it's
1041 useful to define a <em>virtual package</em> whose name
1042 describes that common functionality. (The virtual
1043 packages only exist logically, not physically; that's why
1044 they are called <em>virtual</em>.) The packages with this
1045 particular function will then <em>provide</em> the virtual
1046 package. Thus, any other package requiring that function
1047 can simply depend on the virtual package without having to
1048 specify all possible packages individually.
1052 All packages should use virtual package names where
1053 appropriate, and arrange to create new ones if necessary.
1054 They should not use virtual package names (except privately,
1055 amongst a cooperating group of packages) unless they have
1056 been agreed upon and appear in the list of virtual package
1057 names. (See also <ref id="virtual">)
1061 The latest version of the authoritative list of virtual
1062 package names can be found in the <tt>debian-policy</tt> package.
1063 It is also available from the Debian web mirrors at
1064 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1065 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>.
1069 The procedure for updating the list is described in the preface
1076 <heading>Base system</heading>
1079 The <tt>base system</tt> is a minimum subset of the Debian
1080 GNU/Linux system that is installed before everything else
1081 on a new system. Only very few packages are allowed to form
1082 part of the base system, in order to keep the required disk
1087 The base system consists of all those packages with priority
1088 <tt>required</tt> or <tt>important</tt>. Many of them will
1089 be tagged <tt>essential</tt> (see below).
1094 <heading>Essential packages</heading>
1097 Some packages are tagged <tt>essential</tt> for a system
1098 using the <tt>Essential</tt> control file field.
1099 The format of the <tt>Essential</tt> control field is
1100 described in <ref id="f-Essential">.
1104 Since these packages cannot be easily removed (one has to
1105 specify an extra <em>force option</em> to
1106 <prgn>dpkg</prgn> to do so), this flag must not be used
1107 unless absolutely necessary. A shared library package
1108 must not be tagged <tt>essential</tt>; dependencies will
1109 prevent its premature removal, and we need to be able to
1110 remove it when it has been superseded.
1114 Since dpkg will not prevent upgrading of other packages
1115 while an <tt>essential</tt> package is in an unconfigured
1116 state, all <tt>essential</tt> packages must supply all of
1117 their core functionality even when unconfigured. If the
1118 package cannot satisfy this requirement it must not be
1119 tagged as essential, and any packages depending on this
1120 package must instead have explicit dependency fields as
1125 You must not tag any packages <tt>essential</tt> before
1126 this has been discussed on the <tt>debian-devel</tt>
1127 mailing list and a consensus about doing that has been
1132 <sect id="maintscripts">
1133 <heading>Maintainer Scripts</heading>
1136 The package installation scripts should avoid producing
1137 output which is unnecessary for the user to see and
1138 should rely on <prgn>dpkg</prgn> to stave off boredom on
1139 the part of a user installing many packages. This means,
1140 amongst other things, using the <tt>--quiet</tt> option on
1141 <prgn>install-info</prgn>.
1145 Errors which occur during the execution of an installation
1146 script must be checked and the installation must not
1147 continue after an error.
1151 Note that in general <ref id="scripts"> applies to package
1152 maintainer scripts, too.
1156 You should not use <prgn>dpkg-divert</prgn> on a file
1157 belonging to another package without consulting the
1158 maintainer of that package first.
1162 All packages which supply an instance of a common command
1163 name (or, in general, filename) should generally use
1164 <prgn>update-alternatives</prgn>, so that they may be
1165 installed together. If <prgn>update-alternatives</prgn>
1166 is not used, then each package must use
1167 <tt>Conflicts</tt> to ensure that other packages are
1168 de-installed. (In this case, it may be appropriate to
1169 specify a conflict against earlier versions of something
1170 that previously did not use
1171 <prgn>update-alternatives</prgn>; this is an exception to
1172 the usual rule that versioned conflicts should be
1176 <sect1 id="maintscriptprompt">
1177 <heading>Prompting in maintainer scripts</heading>
1179 Package maintainer scripts may prompt the user if
1180 necessary. Prompting should be done by communicating
1181 through a program, such as <prgn>debconf</prgn>, which
1182 conforms to the Debian Configuration management
1183 specification, version 2 or higher. Prompting the user by
1184 other means, such as by hand<footnote>
1185 From the Jargon file: by hand 2. By extension,
1186 writing code which does something in an explicit or
1187 low-level way for which a presupplied library
1188 (<em>debconf, in this instance</em>) routine ought
1189 to have been available.
1190 </footnote>, is now deprecated.
1194 The Debian Configuration management specification is included
1195 in the <file>debconf_specification</file> files in the
1196 <package>debian-policy</package> package.
1197 It is also available from the Debian web mirrors at
1198 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1199 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>.
1203 Packages which use the Debian Configuration management
1204 specification may contain an additional
1205 <prgn>config</prgn> script and a <tt>templates</tt>
1206 file in their control archive<footnote>
1207 The control.tar.gz inside the .deb.
1208 See <manref name="deb" section="5">.
1210 The <prgn>config</prgn> script might be run before the
1211 <prgn>preinst</prgn> script, and before the package is unpacked
1212 or any of its dependencies or pre-dependencies are satisfied.
1213 Therefore it must work using only the tools present in
1214 <em>essential</em> packages.<footnote>
1215 <package>Debconf</package> or another tool that
1216 implements the Debian Configuration management
1217 specification will also be installed, and any
1218 versioned dependencies on it will be satisfied
1219 before preconfiguration begins.
1224 Packages which use the Debian Configuration management
1225 specification must allow for translation of their messages
1226 by using a gettext-based system such as the one provided by
1227 the <package>po-debconf</package> package.
1231 Packages should try to minimize the amount of prompting
1232 they need to do, and they should ensure that the user
1233 will only ever be asked each question once. This means
1234 that packages should try to use appropriate shared
1235 configuration files (such as <file>/etc/papersize</file> and
1236 <file>/etc/news/server</file>), and shared
1237 <package>debconf</package> variables rather than each
1238 prompting for their own list of required pieces of
1243 It also means that an upgrade should not ask the same
1244 questions again, unless the user has used
1245 <tt>dpkg --purge</tt> to remove the package's configuration.
1246 The answers to configuration questions should be stored in an
1247 appropriate place in <file>/etc</file> so that the user can
1248 modify them, and how this has been done should be
1253 If a package has a vitally important piece of
1254 information to pass to the user (such as "don't run me
1255 as I am, you must edit the following configuration files
1256 first or you risk your system emitting badly-formatted
1257 messages"), it should display this in the
1258 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1259 prompt the user to hit return to acknowledge the
1260 message. Copyright messages do not count as vitally
1261 important (they belong in
1262 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1263 neither do instructions on how to use a program (these
1264 should be in on-line documentation, where all the users
1269 Any necessary prompting should almost always be confined
1270 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1271 script. If it is done in the <prgn>postinst</prgn>, it
1272 should be protected with a conditional so that
1273 unnecessary prompting doesn't happen if a package's
1274 installation fails and the <prgn>postinst</prgn> is
1275 called with <tt>abort-upgrade</tt>,
1276 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1286 <heading>Source packages</heading>
1288 <sect id="standardsversion">
1289 <heading>Standards conformance</heading>
1292 Source packages should specify the most recent version number
1293 of this policy document with which your package complied
1294 when it was last updated.
1298 This information may be used to file bug reports
1299 automatically if your package becomes too much out of date.
1303 The version is specified in the <tt>Standards-Version</tt>
1305 The format of the <tt>Standards-Version</tt> field is
1306 described in <ref id="f-Standards-Version">.
1310 You should regularly, and especially if your package has
1311 become out of date, check for the newest Policy Manual
1312 available and update your package, if necessary. When your
1313 package complies with the new standards you should update the
1314 <tt>Standards-Version</tt> source package field and
1315 release it.<footnote>
1316 See the file <file>upgrading-checklist</file> for
1317 information about policy which has changed between
1318 different versions of this document.
1324 <sect id="pkg-relations">
1325 <heading>Package relationships</heading>
1328 Source packages should specify which binary packages they
1329 require to be installed or not to be installed in order to
1330 build correctly. For example, if building a package
1331 requires a certain compiler, then the compiler should be
1332 specified as a build-time dependency.
1336 It is not necessary to explicitly specify build-time
1337 relationships on a minimal set of packages that are always
1338 needed to compile, link and put in a Debian package a
1339 standard "Hello World!" program written in C or C++. The
1340 required packages are called <em>build-essential</em>, and
1341 an informational list can be found in
1342 <file>/usr/share/doc/build-essential/list</file> (which is
1343 contained in the <tt>build-essential</tt>
1346 <list compact="compact">
1348 This allows maintaining the list separately
1349 from the policy documents (the list does not
1350 need the kind of control that the policy
1354 Having a separate package allows one to install
1355 the build-essential packages on a machine, as
1356 well as allowing other packages such as tasks to
1357 require installation of the build-essential
1358 packages using the depends relation.
1361 The separate package allows bug reports against
1362 the list to be categorized separately from
1363 the policy management process in the BTS.
1370 When specifying the set of build-time dependencies, one
1371 should list only those packages explicitly required by the
1372 build. It is not necessary to list packages which are
1373 required merely because some other package in the list of
1374 build-time dependencies depends on them.<footnote>
1375 The reason for this is that dependencies change, and
1376 you should list all those packages, and <em>only</em>
1377 those packages that <em>you</em> need directly. What
1378 others need is their business. For example, if you
1379 only link against <file>libimlib</file>, you will need to
1380 build-depend on <package>libimlib2-dev</package> but
1381 not against any <tt>libjpeg*</tt> packages, even
1382 though <tt>libimlib2-dev</tt> currently depends on
1383 them: installation of <package>libimlib2-dev</package>
1384 will automatically ensure that all of its run-time
1385 dependencies are satisfied.
1390 If build-time dependencies are specified, it must be
1391 possible to build the package and produce working binaries
1392 on a system with only essential and build-essential
1393 packages installed and also those required to satisfy the
1394 build-time relationships (including any implied
1395 relationships). In particular, this means that version
1396 clauses should be used rigorously in build-time
1397 relationships so that one cannot produce bad or
1398 inconsistently configured packages when the relationships
1399 are properly satisfied.
1403 <ref id="relationships"> explains the technical details.
1408 <heading>Changes to the upstream sources</heading>
1411 If changes to the source code are made that are not
1412 specific to the needs of the Debian system, they should be
1413 sent to the upstream authors in whatever form they prefer
1414 so as to be included in the upstream version of the
1419 If you need to configure the package differently for
1420 Debian or for Linux, and the upstream source doesn't
1421 provide a way to do so, you should add such configuration
1422 facilities (for example, a new <prgn>autoconf</prgn> test
1423 or <tt>#define</tt>) and send the patch to the upstream
1424 authors, with the default set to the way they originally
1425 had it. You can then easily override the default in your
1426 <file>debian/rules</file> or wherever is appropriate.
1430 You should make sure that the <prgn>configure</prgn> utility
1431 detects the correct architecture specification string
1432 (refer to <ref id="arch-spec"> for details).
1436 If you need to edit a <prgn>Makefile</prgn> where GNU-style
1437 <prgn>configure</prgn> scripts are used, you should edit the
1438 <file>.in</file> files rather than editing the
1439 <prgn>Makefile</prgn> directly. This allows the user to
1440 reconfigure the package if necessary. You should
1441 <em>not</em> configure the package and edit the generated
1442 <prgn>Makefile</prgn>! This makes it impossible for someone
1443 else to later reconfigure the package without losing the
1449 <sect id="dpkgchangelog">
1450 <heading>Debian changelog: <file>debian/changelog</file></heading>
1453 Changes in the Debian version of the package should be
1454 briefly explained in the Debian changelog file
1455 <file>debian/changelog</file>.<footnote>
1457 Mistakes in changelogs are usually best rectified by
1458 making a new changelog entry rather than "rewriting
1459 history" by editing old changelog entries.
1462 This includes modifications
1463 made in the Debian package compared to the upstream one
1464 as well as other changes and updates to the package.
1466 Although there is nothing stopping an author who is also
1467 the Debian maintainer from using this changelog for all
1468 their changes, it will have to be renamed if the Debian
1469 and upstream maintainers become different people. In such
1470 a case, however, it might be better to maintain the package
1471 as a non-native package.
1480 The format of the <file>debian/changelog</file> allows the
1481 package building tools to discover which version of the package
1482 is being built and find out other release-specific information.
1486 That format is a series of entries like this:
1488 <example compact="compact">
1489 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1491 [optional blank line(s), stripped]
1493 * <var>change details</var>
1494 <var>more change details</var>
1496 [blank line(s), included in output of dpkg-parsechangelog]
1498 * <var>even more change details</var>
1500 [optional blank line(s), stripped]
1502 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1507 <var>package</var> and <var>version</var> are the source
1508 package name and version number.
1512 <var>distribution(s)</var> lists the distributions where
1513 this version should be installed when it is uploaded - it
1514 is copied to the <tt>Distribution</tt> field in the
1515 <file>.changes</file> file. See <ref id="f-Distribution">.
1519 <var>urgency</var> is the value for the <tt>Urgency</tt>
1520 field in the <file>.changes</file> file for the upload
1521 (see <ref id="f-Urgency">). It is not possible to specify
1522 an urgency containing commas; commas are used to separate
1523 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1524 <prgn>dpkg</prgn> changelog format (though there is
1525 currently only one useful <var>keyword</var>,
1530 The change details may in fact be any series of lines
1531 starting with at least two spaces, but conventionally each
1532 change starts with an asterisk and a separating space and
1533 continuation lines are indented so as to bring them in
1534 line with the start of the text above. Blank lines may be
1535 used here to separate groups of changes, if desired.
1539 If this upload resolves bugs recorded in the Bug Tracking
1540 System (BTS), they may be automatically closed on the
1541 inclusion of this package into the Debian archive by
1542 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1543 in the change details.<footnote>
1544 To be precise, the string should match the following
1545 Perl regular expression:
1547 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1549 Then all of the bug numbers listed will be closed by the
1550 archive maintenance script (<prgn>katie</prgn>) using the
1551 <var>version</var> of the changelog entry.
1553 This information is conveyed via the <tt>Closes</tt> field
1554 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1558 The maintainer name and email address used in the changelog
1559 should be the details of the person uploading <em>this</em>
1560 version. They are <em>not</em> necessarily those of the
1561 usual package maintainer. The information here will be
1562 copied to the <tt>Changed-By</tt> field in the
1563 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1564 and then later used to send an acknowledgement when the
1565 upload has been installed.
1569 The <var>date</var> should be in RFC822 format<footnote>
1570 This is generated by <tt>date -R</tt>.
1571 </footnote>; it should include the time zone specified
1572 numerically, with the time zone name or abbreviation
1573 optionally present as a comment in parentheses.
1577 The first "title" line with the package name should start
1578 at the left hand margin; the "trailer" line with the
1579 maintainer and date details should be preceded by exactly
1580 one space. The maintainer details and the date must be
1581 separated by exactly two spaces.
1585 For more information on placement of the changelog files
1586 within binary packages, please see <ref id="changelogs">.
1589 <sect1><heading>Alternative changelog formats</heading>
1592 In non-experimental packages you must use a format for
1593 <file>debian/changelog</file> which is supported by the most
1594 recent released version of <prgn>dpkg</prgn>.
1598 It is possible to use a format different from the standard
1599 one by providing a changelog parser for the format you wish
1600 to use. The parser must have an API compatible with that
1601 expected by <prgn>dpkg-genchanges</prgn> and
1602 <prgn>dpkg-gencontrol</prgn>, and it must not interact with
1605 If there is general interest in the new format, you should
1606 contact the <package>dpkg</package> maintainer to have the
1607 parser script for it included in the <prgn>dpkg</prgn>
1608 package. (You will need to agree that the parser and its
1609 man page may be distributed under the GNU GPL, just as the rest
1610 of <prgn>dpkg</prgn> is.)
1615 <sect id="dpkgcopyright">
1616 <heading>Copyright: <file>debian/copyright</file></heading>
1618 Every package must be accompanied by a verbatim copy of
1619 its copyright and distribution license in the file
1620 <file>/usr/share/doc/<var>package</var>/copyright</file>
1621 (see <ref id="copyrightfile"> for further details). Also see
1622 <ref id="pkgcopyright"> for further considerations relayed
1623 to copyrights for packages.
1627 <heading>Error trapping in makefiles</heading>
1630 When <prgn>make</prgn> invokes a command in a makefile
1631 (including your package's upstream makefiles and
1632 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1633 means that <prgn>sh</prgn>'s usual bad error handling
1634 properties apply: if you include a miniature script as one
1635 of the commands in your makefile you'll find that if you
1636 don't do anything about it then errors are not detected
1637 and <prgn>make</prgn> will blithely continue after
1642 Every time you put more than one shell command (this
1643 includes using a loop) in a makefile command you
1644 must make sure that errors are trapped. For
1645 simple compound commands, such as changing directory and
1646 then running a program, using <tt>&&</tt> rather
1647 than semicolon as a command separator is sufficient. For
1648 more complex commands including most loops and
1649 conditionals you should include a separate <tt>set -e</tt>
1650 command at the start of every makefile command that's
1651 actually one of these miniature shell scripts.
1655 <sect id="timestamps">
1656 <heading>Time Stamps</heading>
1658 Maintainers should preserve the modification times of the
1659 upstream source files in a package, as far as is reasonably
1661 The rationale is that there is some information conveyed
1662 by knowing the age of the file, for example, you could
1663 recognize that some documentation is very old by looking
1664 at the modification time, so it would be nice if the
1665 modification time of the upstream source would be
1671 <sect id="restrictions">
1672 <heading>Restrictions on objects in source packages</heading>
1675 The source package may not contain any hard links<footnote>
1677 This is not currently detected when building source
1678 packages, but only when extracting
1682 Hard links may be permitted at some point in the
1683 future, but would require a fair amount of
1686 </footnote>, device special files, sockets or setuid or
1687 setgid files.<footnote>
1688 Setgid directories are allowed.
1693 <sect id="debianrules">
1694 <heading>Main building script: <file>debian/rules</file></heading>
1697 This file must be an executable makefile, and contains the
1698 package-specific recipes for compiling the package and
1699 building binary package(s) from the source.
1703 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1704 so that it can be invoked by saying its name rather than
1705 invoking <prgn>make</prgn> explicitly.
1709 Since an interactive <file>debian/rules</file> script makes it
1710 impossible to auto-compile that package and also makes it
1711 hard for other people to reproduce the same binary
1712 package, all <em>required targets</em> MUST be
1713 non-interactive. At a minimum, required targets are the
1714 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1715 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1716 <em>binary-indep</em>, and <em>build</em>. It also follows
1717 that any target that these targets depend on must also be
1722 The targets are as follows (required unless stated otherwise):
1724 <tag><tt>build</tt></tag>
1727 The <tt>build</tt> target should perform all the
1728 configuration and compilation of the package.
1729 If a package has an interactive pre-build
1730 configuration routine, the Debianized source package
1731 must either be built after this has taken place (so
1732 that the binary package can be built without rerunning
1733 the configuration) or the configuration routine
1734 modified to become non-interactive. (The latter is
1735 preferable if there are architecture-specific features
1736 detected by the configuration routine.)
1740 For some packages, notably ones where the same
1741 source tree is compiled in different ways to produce
1742 two binary packages, the <tt>build</tt> target
1743 does not make much sense. For these packages it is
1744 good enough to provide two (or more) targets
1745 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1746 for each of the ways of building the package, and a
1747 <tt>build</tt> target that does nothing. The
1748 <tt>binary</tt> target will have to build the
1749 package in each of the possible ways and make the
1750 binary package out of each.
1754 The <tt>build</tt> target must not do anything
1755 that might require root privilege.
1759 The <tt>build</tt> target may need to run the
1760 <tt>clean</tt> target first - see below.
1764 When a package has a configuration and build routine
1765 which takes a long time, or when the makefiles are
1766 poorly designed, or when <tt>build</tt> needs to
1767 run <tt>clean</tt> first, it is a good idea to
1768 <tt>touch build</tt> when the build process is
1769 complete. This will ensure that if <tt>debian/rules
1770 build</tt> is run again it will not rebuild the whole
1772 Another common way to do this is for <tt>build</tt>
1773 to depend on <prgn>build-stamp</prgn> and to do
1774 nothing else, and for the <prgn>build-stamp</prgn>
1775 target to do the building and to <tt>touch
1776 build-stamp</tt> on completion. This is
1777 especially useful if the build routine creates a
1778 file or directory called <tt>build</tt>; in such a
1779 case, <tt>build</tt> will need to be listed as
1780 a phony target (i.e., as a dependency of the
1781 <tt>.PHONY</tt> target). See the documentation of
1782 <prgn>make</prgn> for more information on phony
1788 <tag><tt>build-arch</tt> (optional),
1789 <tt>build-indep</tt> (optional)
1793 A package may also provide both of the targets
1794 <tt>build-arch</tt> and <tt>build-indep</tt>.
1795 The <tt>build-arch</tt> target, if provided, should
1796 perform all the configuration and compilation required
1797 for producing all architecture-dependant binary packages
1798 (those packages for which the body of the
1799 <tt>Architecture</tt> field in <tt>debian/control</tt>
1800 is not <tt>all</tt>).
1801 Similarly, the <tt>build-indep</tt> target, if
1802 provided, should perform all the configuration and
1803 compilation required for producing all
1804 architecture-independent binary packages
1805 (those packages for which the body of the
1806 <tt>Architecture</tt> field in <tt>debian/control</tt>
1808 The <tt>build</tt> target should depend on those of the
1809 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1810 are provided in the rules file.
1814 If one or both of the targets <tt>build-arch</tt> and
1815 <tt>build-indep</tt> are not provided, then invoking
1816 <file>debian/rules</file> with one of the not-provided
1817 targets as arguments should produce a exit status code
1818 of 2. Usually this is provided automatically by make
1819 if the target is missing.
1823 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1824 must not do anything that might require root privilege.
1828 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1829 <tt>binary-indep</tt>
1833 The <tt>binary</tt> target must be all that is
1834 necessary for the user to build the binary package(s)
1835 produced from this source package. It is
1836 split into two parts: <prgn>binary-arch</prgn> builds
1837 the binary packages which are specific to a particular
1838 architecture, and <tt>binary-indep</tt> builds
1839 those which are not.
1842 <tt>binary</tt> may be (and commonly is) a target with
1843 no commands which simply depends on
1844 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1847 Both <tt>binary-*</tt> targets should depend on the
1848 <tt>build</tt> target, or on the appropriate
1849 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1850 provided, so that the package is built if it has not
1851 been already. It should then create the relevant
1852 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1853 make their control files and <prgn>dpkg-deb</prgn> to
1854 build them and place them in the parent of the top
1859 Both the <tt>binary-arch</tt> and
1860 <tt>binary-indep</tt> targets <em>must</em> exist.
1861 If one of them has nothing to do (which will always be
1862 the case if the source generates only a single binary
1863 package, whether architecture-dependent or not), it
1864 must still exist and must always succeed.
1868 The <tt>binary</tt> targets must be invoked as
1870 The <prgn>fakeroot</prgn> package often allows one
1871 to build a package correctly even without being
1877 <tag><tt>clean</tt></tag>
1880 This must undo any effects that the <tt>build</tt>
1881 and <tt>binary</tt> targets may have had, except
1882 that it should leave alone any output files created in
1883 the parent directory by a run of a <tt>binary</tt>
1888 If a <tt>build</tt> file is touched at the end of
1889 the <tt>build</tt> target, as suggested above, it
1890 should be removed as the first action that
1891 <tt>clean</tt> performs, so that running
1892 <tt>build</tt> again after an interrupted
1893 <tt>clean</tt> doesn't think that everything is
1898 The <tt>clean</tt> target may need to be
1899 invoked as root if <tt>binary</tt> has been
1900 invoked since the last <tt>clean</tt>, or if
1901 <tt>build</tt> has been invoked as root (since
1902 <tt>build</tt> may create directories, for
1907 <tag><tt>get-orig-source</tt> (optional)</tag>
1910 This target fetches the most recent version of the
1911 original source package from a canonical archive site
1912 (via FTP or WWW, for example), does any necessary
1913 rearrangement to turn it into the original source
1914 tar file format described below, and leaves it in the
1919 This target may be invoked in any directory, and
1920 should take care to clean up any temporary files it
1925 This target is optional, but providing it if
1926 possible is a good idea.
1930 <tag><tt>patch</tt> (optional)</tag>
1933 This target performs whatever additional actions are
1934 required to make the source ready for editing (unpacking
1935 additional upstream archives, applying patches, etc.).
1936 It is recommended to be implemented for any package where
1937 <tt>dpkg-source -x</tt> does not result in source ready
1938 for additional modification. See
1939 <ref id="readmesource">.
1945 The <tt>build</tt>, <tt>binary</tt> and
1946 <tt>clean</tt> targets must be invoked with the current
1947 directory being the package's top-level directory.
1952 Additional targets may exist in <file>debian/rules</file>,
1953 either as published or undocumented interfaces or for the
1954 package's internal use.
1958 The architectures we build on and build for are determined
1959 by <prgn>make</prgn> variables using the utility
1960 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
1961 You can determine the
1962 Debian architecture and the GNU style architecture
1963 specification string for the build machine (the machine type
1964 we are building on) as well as for the host machine (the
1965 machine type we are building for). Here is a list of
1966 supported <prgn>make</prgn> variables:
1967 <list compact="compact">
1969 <tt>DEB_*_ARCH</tt> (the Debian architecture)
1972 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
1973 specification string)
1976 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
1977 <tt>DEB_*_GNU_TYPE</tt>)
1980 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
1981 <tt>DEB_*_GNU_TYPE</tt>)
1983 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
1984 the build machine or <tt>HOST</tt> for specification of the
1989 Backward compatibility can be provided in the rules file
1990 by setting the needed variables to suitable default
1991 values; please refer to the documentation of
1992 <prgn>dpkg-architecture</prgn> for details.
1996 It is important to understand that the <tt>DEB_*_ARCH</tt>
1997 string only determines which Debian architecture we are
1998 building on or for. It should not be used to get the CPU
1999 or system information; the GNU style variables should be
2003 <sect1 id="debianrules-options">
2004 <heading><file>debian/rules</file> and
2005 <tt>DEB_BUILD_OPTIONS</tt></heading>
2008 Supporting the standardized environment variable
2009 <tt>DEB_BUILD_OPTIONS</tt> is recommended. This variable can
2010 contain several flags to change how a package is compiled and
2011 built. Each flag must be in the form <var>flag</var> or
2012 <var>flag</var>=<var>options</var>. If multiple flags are
2013 given, they must be separated by whitespace.<footnote>
2014 Some packages support any delimiter, but whitespace is the
2015 easiest to parse inside a makefile and avoids ambiguity with
2016 flag values that contain commas.
2018 <var>flag</var> must start with a lowercase letter
2019 (<tt>a-z</tt>) and consist only of lowercase letters,
2020 numbers (<tt>0-9</tt>), and the characters
2021 <tt>-</tt> and <tt>_</tt> (hyphen and underscore).
2022 <var>options</var> must not contain whitespace. The same
2023 tag should not be given multiple times with conflicting
2024 values. Package maintainers may assume that
2025 <tt>DEB_BUILD_OPTIONS</tt> will not contain conflicting tags.
2029 The meaning of the following tags has been standardized:
2033 This tag says to not run any build-time test suite
2034 provided by the package.
2038 The presence of this tag means that the package should
2039 be compiled with a minimum of optimization. For C
2040 programs, it is best to add <tt>-O0</tt> to
2041 <tt>CFLAGS</tt> (although this is usually the default).
2042 Some programs might fail to build or run at this level
2043 of optimization; it may be necessary to use
2044 <tt>-O1</tt>, for example.
2048 This tag means that the debugging symbols should not be
2049 stripped from the binary during installation, so that
2050 debugging information may be included in the package.
2052 <tag>parallel=n</tag>
2054 This tag means that the package should be built using up
2055 to <tt>n</tt> parallel processes if the package build
2056 system supports this.<footnote>
2057 Packages built with <tt>make</tt> can often implement
2058 this by passing the <tt>-j</tt><var>n</var> option to
2061 If the package build system does not support parallel
2062 builds, this string must be ignored. If the package
2063 build system only supports a lower level of concurrency
2064 than <var>n</var>, the package should be built using as
2065 many parallel processes as the package build system
2066 supports. It is up to the package maintainer to decide
2067 whether the package build times are long enough and the
2068 package build system is robust enough to make supporting
2069 parallel builds worthwhile.
2075 Unknown flags must be ignored by <file>debian/rules</file>.
2079 The following makefile snippet is an example of how one may
2080 implement the build options; you will probably have to
2081 massage this example in order to make it work for your
2083 <example compact="compact">
2086 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
2087 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
2088 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
2089 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
2091 ifneq (,$(filter noopt,$(DEB_BUILD_OPTIONS)))
2096 ifeq (,$(filter nostrip,$(DEB_BUILD_OPTIONS)))
2097 INSTALL_PROGRAM += -s
2099 ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2100 NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2101 MAKEFLAGS += -j$(NUMJOBS)
2106 ifeq (,$(filter nocheck,$(DEB_BUILD_OPTIONS)))
2107 # Code to run the package test suite.
2114 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2115 <sect id="substvars">
2116 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2119 When <prgn>dpkg-gencontrol</prgn>,
2120 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2121 generate control files they perform variable substitutions
2122 on their output just before writing it. Variable
2123 substitutions have the form <tt>${<var>variable</var>}</tt>.
2124 The optional file <file>debian/substvars</file> contains
2125 variable substitutions to be used; variables can also be set
2126 directly from <file>debian/rules</file> using the <tt>-V</tt>
2127 option to the source packaging commands, and certain
2128 predefined variables are also available.
2132 The <file>debian/substvars</file> file is usually generated and
2133 modified dynamically by <file>debian/rules</file> targets, in
2134 which case it must be removed by the <tt>clean</tt> target.
2138 See <manref name="deb-substvars" section="5"> for full
2139 details about source variable substitutions, including the
2140 format of <file>debian/substvars</file>.</p>
2143 <sect id="debianwatch">
2144 <heading>Optional upstream source location: <file>debian/watch</file></heading>
2147 This is an optional, recommended control file for the
2148 <tt>uscan</tt> utility which defines how to automatically
2149 scan ftp or http sites for newly available updates of the
2150 package. This is used by <url id="
2151 http://dehs.alioth.debian.org/"> and other Debian QA tools
2152 to help with quality control and maintenance of the
2153 distribution as a whole.
2158 <sect id="debianfiles">
2159 <heading>Generated files list: <file>debian/files</file></heading>
2162 This file is not a permanent part of the source tree; it
2163 is used while building packages to record which files are
2164 being generated. <prgn>dpkg-genchanges</prgn> uses it
2165 when it generates a <file>.changes</file> file.
2169 It should not exist in a shipped source package, and so it
2170 (and any backup files or temporary files such as
2171 <file>files.new</file><footnote>
2172 <file>files.new</file> is used as a temporary file by
2173 <prgn>dpkg-gencontrol</prgn> and
2174 <prgn>dpkg-distaddfile</prgn> - they write a new
2175 version of <tt>files</tt> here before renaming it,
2176 to avoid leaving a corrupted copy if an error
2178 </footnote>) should be removed by the
2179 <tt>clean</tt> target. It may also be wise to
2180 ensure a fresh start by emptying or removing it at the
2181 start of the <tt>binary</tt> target.
2185 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2186 package, it adds an entry to <file>debian/files</file> for the
2187 <file>.deb</file> file that will be created when <tt>dpkg-deb
2188 --build</tt> is run for that binary package. So for most
2189 packages all that needs to be done with this file is to
2190 delete it in the <tt>clean</tt> target.
2194 If a package upload includes files besides the source
2195 package and any binary packages whose control files were
2196 made with <prgn>dpkg-gencontrol</prgn> then they should be
2197 placed in the parent of the package's top-level directory
2198 and <prgn>dpkg-distaddfile</prgn> should be called to add
2199 the file to the list in <file>debian/files</file>.</p>
2202 <sect id="embeddedfiles">
2203 <heading>Convenience copies of code</heading>
2206 Some software packages include in their distribution convenience
2207 copies of code from other software packages, generally so that
2208 users compiling from source don't have to download multiple
2209 packages. Debian packages should not make use of these
2210 convenience copies unless the included package is explicitly
2211 intended to be used in this way.<footnote>
2212 For example, parts of the GNU build system work like this.
2214 If the included code is already in the Debian archive in the
2215 form of a library, the Debian packaging should ensure that
2216 binary packages reference the libraries already in Debian and
2217 the convenience copy is not used. If the included code is not
2218 already in Debian, it should be packaged separately as a
2219 prerequisite if possible.
2221 Having multiple copies of the same code in Debian is
2222 inefficient, often creates either static linking or shared
2223 library conflicts, and, most importantly, increases the
2224 difficulty of handling security vulnerabilities in the
2230 <sect id="readmesource">
2231 <heading>Source package handling:
2232 <file>debian/README.source</file></heading>
2235 If running <prgn>dpkg-source -x</prgn> on a source package
2236 doesn't produce the source of the package, ready for editing,
2237 and allow one to make changes and run
2238 <prgn>dpkg-buildpackage</prgn> to produce a modified package
2239 without taking any additional steps, creating a
2240 <file>debian/README.source</file> documentation file is
2241 recommended. This file should explain how to do all of the
2244 <item>Generate the fully patched source, in a form ready for
2245 editing, that would be built to create Debian
2246 packages. Doing this with a <tt>patch</tt> target in
2247 <file>debian/rules</file> is recommended; see
2248 <ref id="debianrules">.</item>
2249 <item>Modify the source and save those modifications so that
2250 they will be applied when building the package.</item>
2251 <item>Remove source modifications that are currently being
2252 applied when building the package.</item>
2253 <item>Optionally, document what steps are necessary to
2254 upgrade the Debian source package to a new upstream version,
2255 if applicable.</item>
2257 This explanation should include specific commands and mention
2258 any additional required Debian packages. It should not assume
2259 familiarity with any specific Debian packaging system or patch
2264 This explanation may refer to a documentation file installed by
2265 one of the package's build dependencies provided that the
2266 referenced documentation clearly explains these tasks and is not
2267 a general reference manual.
2271 <file>debian/README.source</file> may also include any other
2272 information that would be helpful to someone modifying the
2273 source package. Even if the package doesn't fit the above
2274 description, maintainers are encouraged to document in a
2275 <file>debian/README.source</file> file any source package with a
2276 particularly complex or unintuitive source layout or build
2277 system (for example, a package that builds the same source
2278 multiple times to generate different binary packages).
2284 <chapt id="controlfields">
2285 <heading>Control files and their fields</heading>
2288 The package management system manipulates data represented in
2289 a common format, known as <em>control data</em>, stored in
2290 <em>control files</em>.
2291 Control files are used for source packages, binary packages and
2292 the <file>.changes</file> files which control the installation
2293 of uploaded files<footnote>
2294 <prgn>dpkg</prgn>'s internal databases are in a similar
2299 <sect id="controlsyntax">
2300 <heading>Syntax of control files</heading>
2303 A control file consists of one or more paragraphs of
2305 The paragraphs are also sometimes referred to as stanzas.
2307 The paragraphs are separated by blank lines. Some control
2308 files allow only one paragraph; others allow several, in
2309 which case each paragraph usually refers to a different
2310 package. (For example, in source packages, the first
2311 paragraph refers to the source package, and later paragraphs
2312 refer to binary packages generated from the source.)
2316 Each paragraph consists of a series of data fields; each
2317 field consists of the field name, followed by a colon and
2318 then the data/value associated with that field. It ends at
2319 the end of the (logical) line. Horizontal whitespace
2320 (spaces and tabs) may occur immediately before or after the
2321 value and is ignored there; it is conventional to put a
2322 single space after the colon. For example, a field might
2324 <example compact="compact">
2327 the field name is <tt>Package</tt> and the field value
2332 Many fields' values may span several lines; in this case
2333 each continuation line must start with a space or a tab.
2334 Any trailing spaces or tabs at the end of individual
2335 lines of a field value are ignored.
2339 In fields where it is specified that lines may not wrap,
2340 only a single line of data is allowed and whitespace is not
2341 significant in a field body. Whitespace must not appear
2342 inside names (of packages, architectures, files or anything
2343 else) or version numbers, or between the characters of
2344 multi-character version relationships.
2348 Field names are not case-sensitive, but it is usual to
2349 capitalize the field names using mixed case as shown below.
2353 Blank lines, or lines consisting only of spaces and tabs,
2354 are not allowed within field values or between fields - that
2355 would mean a new paragraph.
2360 <sect id="sourcecontrolfiles">
2361 <heading>Source package control files -- <file>debian/control</file></heading>
2364 The <file>debian/control</file> file contains the most vital
2365 (and version-independent) information about the source package
2366 and about the binary packages it creates.
2370 The first paragraph of the control file contains information about
2371 the source package in general. The subsequent sets each describe a
2372 binary package that the source tree builds.
2376 The fields in the general paragraph (the first one, for the source
2379 <list compact="compact">
2380 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2381 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2382 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2383 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2384 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2385 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2386 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2387 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2392 The fields in the binary package paragraphs are:
2394 <list compact="compact">
2395 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2396 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2397 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2398 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2399 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2400 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2401 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2402 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2407 The syntax and semantics of the fields are described below.
2413 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2414 generate control files for binary packages (see below), by
2415 <prgn>dpkg-genchanges</prgn> to generate the
2416 <tt>.changes</tt> file to accompany the upload, and by
2417 <prgn>dpkg-source</prgn> when it creates the
2418 <file>.dsc</file> source control file as part of a source
2419 archive. Many fields are permitted to span multiple lines in
2420 <file>debian/control</file> but not in any other control
2421 file. These tools are responsible for removing the line
2422 breaks from such fields when using fields from
2423 <file>debian/control</file> to generate other control files.
2427 The fields here may contain variable references - their
2428 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2429 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2430 when they generate output control files.
2431 See <ref id="substvars"> for details.
2436 <sect id="binarycontrolfiles">
2437 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2440 The <file>DEBIAN/control</file> file contains the most vital
2441 (and version-dependent) information about a binary package.
2445 The fields in this file are:
2447 <list compact="compact">
2448 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2449 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2450 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2451 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2452 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2453 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2454 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2455 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2456 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2457 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2458 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2459 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2464 <sect id="debiansourcecontrolfiles">
2465 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2468 This file contains a series of fields, identified and
2469 separated just like the fields in the control file of
2470 a binary package. The fields are listed below; their
2471 syntax is described above, in <ref id="pkg-controlfields">.
2473 <list compact="compact">
2474 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2475 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2476 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2477 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2478 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2479 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2480 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2481 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2482 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2483 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2484 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2489 The source package control file is generated by
2490 <prgn>dpkg-source</prgn> when it builds the source
2491 archive, from other files in the source package,
2492 described above. When unpacking, it is checked against
2493 the files and directories in the other parts of the
2499 <sect id="debianchangesfiles">
2500 <heading>Debian changes files -- <file>.changes</file></heading>
2503 The .changes files are used by the Debian archive maintenance
2504 software to process updates to packages. They contain one
2505 paragraph which contains information from the
2506 <tt>debian/control</tt> file and other data about the
2507 source package gathered via <tt>debian/changelog</tt>
2508 and <tt>debian/rules</tt>.
2512 The fields in this file are:
2514 <list compact="compact">
2515 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2516 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2517 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2518 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2519 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2520 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2521 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2522 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2523 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2524 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2525 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2526 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2527 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2528 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2533 <sect id="controlfieldslist">
2534 <heading>List of fields</heading>
2536 <sect1 id="f-Source">
2537 <heading><tt>Source</tt></heading>
2540 This field identifies the source package name.
2544 In <file>debian/control</file> or a <file>.dsc</file> file,
2545 this field must contain only the name of the source package.
2549 In a binary package control file or a <file>.changes</file>
2550 file, the source package name may be followed by a version
2551 number in parentheses<footnote>
2552 It is customary to leave a space after the package name
2553 if a version number is specified.
2555 This version number may be omitted (and is, by
2556 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2557 the <tt>Version</tt> field of the binary package in
2558 question. The field itself may be omitted from a binary
2559 package control file when the source package has the same
2560 name and version as the binary package.
2564 <sect1 id="f-Maintainer">
2565 <heading><tt>Maintainer</tt></heading>
2568 The package maintainer's name and email address. The name
2569 should come first, then the email address inside angle
2570 brackets <tt><></tt> (in RFC822 format).
2574 If the maintainer's name contains a full stop then the
2575 whole field will not work directly as an email address due
2576 to a misfeature in the syntax specified in RFC822; a
2577 program using this field as an address must check for this
2578 and correct the problem if necessary (for example by
2579 putting the name in round brackets and moving it to the
2580 end, and bringing the email address forward).
2584 <sect1 id="f-Uploaders">
2585 <heading><tt>Uploaders</tt></heading>
2588 List of the names and email addresses of co-maintainers of
2589 the package, if any. If the package has other maintainers
2590 beside the one named in the
2591 <qref id="f-Maintainer">Maintainer field</qref>, their
2592 names and email addresses should be listed here. The
2593 format is the same as that of the Maintainer tag, and
2594 multiple entries should be comma separated. Currently,
2595 this field is restricted to a single line of data. This
2596 is an optional field.
2599 Any parser that interprets the Uploaders field in
2600 <file>debian/control</file> must permit it to span multiple
2601 lines. Line breaks in an Uploaders field that spans multiple
2602 lines are not significant and the semantics of the field are
2603 the same as if the line breaks had not been present.
2607 <sect1 id="f-Changed-By">
2608 <heading><tt>Changed-By</tt></heading>
2611 The name and email address of the person who changed the
2612 said package. Usually the name of the maintainer.
2613 All the rules for the Maintainer field apply here, too.
2617 <sect1 id="f-Section">
2618 <heading><tt>Section</tt></heading>
2621 This field specifies an application area into which the package
2622 has been classified. See <ref id="subsections">.
2626 When it appears in the <file>debian/control</file> file,
2627 it gives the value for the subfield of the same name in
2628 the <tt>Files</tt> field of the <file>.changes</file> file.
2629 It also gives the default for the same field in the binary
2634 <sect1 id="f-Priority">
2635 <heading><tt>Priority</tt></heading>
2638 This field represents how important that it is that the user
2639 have the package installed. See <ref id="priorities">.
2643 When it appears in the <file>debian/control</file> file,
2644 it gives the value for the subfield of the same name in
2645 the <tt>Files</tt> field of the <file>.changes</file> file.
2646 It also gives the default for the same field in the binary
2651 <sect1 id="f-Package">
2652 <heading><tt>Package</tt></heading>
2655 The name of the binary package.
2659 Package names must consist only of lower case letters
2660 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
2661 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
2662 They must be at least two characters long and must start
2663 with an alphanumeric character.
2667 <sect1 id="f-Architecture">
2668 <heading><tt>Architecture</tt></heading>
2671 Depending on context and the control file used, the
2672 <tt>Architecture</tt> field can include the following sets of
2675 <item>A unique single word identifying a Debian machine
2676 architecture, see <ref id="arch-spec">.
2677 <item><tt>all</tt>, which indicates an
2678 architecture-independent package.
2679 <item><tt>any</tt>, which indicates a package available
2680 for building on any architecture.
2681 <item><tt>source</tt>, which indicates a source package.
2686 In the main <file>debian/control</file> file in the source
2687 package, or in the source package control file
2688 <file>.dsc</file>, one may specify a list of architectures
2689 separated by spaces, or the special values <tt>any</tt> or
2694 Specifying <tt>any</tt> indicates that the source package
2695 isn't dependent on any particular architecture and should
2696 compile fine on any one. The produced binary package(s)
2697 will be specific to whatever the current build architecture
2699 This is the most often used setting, and is recommended
2700 for new packages that aren't <tt>Architecture: all</tt>.
2705 Specifying a list of architectures indicates that the source
2706 will build an architecture-dependent package, and will only
2707 work correctly on the listed architectures.<footnote>
2708 This is a setting used for a minority of cases where the
2709 program is not portable. Generally, it should not be used
2715 In a <file>.changes</file> file, the <tt>Architecture</tt>
2716 field lists the architecture(s) of the package(s)
2717 currently being uploaded. This will be a list; if the
2718 source for the package is also being uploaded, the special
2719 entry <tt>source</tt> is also present.
2723 See <ref id="debianrules"> for information how to get the
2724 architecture for the build process.
2728 <sect1 id="f-Essential">
2729 <heading><tt>Essential</tt></heading>
2732 This is a boolean field which may occur only in the
2733 control file of a binary package or in a per-package fields
2734 paragraph of a main source control data file.
2738 If set to <tt>yes</tt> then the package management system
2739 will refuse to remove the package (upgrading and replacing
2740 it is still possible). The other possible value is <tt>no</tt>,
2741 which is the same as not having the field at all.
2746 <heading>Package interrelationship fields:
2747 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2748 <tt>Recommends</tt>, <tt>Suggests</tt>,
2749 <tt>Breaks</tt>, <tt>Conflicts</tt>,
2750 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2754 These fields describe the package's relationships with
2755 other packages. Their syntax and semantics are described
2756 in <ref id="relationships">.</p>
2759 <sect1 id="f-Standards-Version">
2760 <heading><tt>Standards-Version</tt></heading>
2763 The most recent version of the standards (the policy
2764 manual and associated texts) with which the package
2769 The version number has four components: major and minor
2770 version number and major and minor patch level. When the
2771 standards change in a way that requires every package to
2772 change the major number will be changed. Significant
2773 changes that will require work in many packages will be
2774 signaled by a change to the minor number. The major patch
2775 level will be changed for any change to the meaning of the
2776 standards, however small; the minor patch level will be
2777 changed when only cosmetic, typographical or other edits
2778 are made which neither change the meaning of the document
2779 nor affect the contents of packages.
2783 Thus only the first three components of the policy version
2784 are significant in the <em>Standards-Version</em> control
2785 field, and so either these three components or the all
2786 four components may be specified.<footnote>
2787 In the past, people specified the full version number
2788 in the Standards-Version field, for example "2.3.0.0".
2789 Since minor patch-level changes don't introduce new
2790 policy, it was thought it would be better to relax
2791 policy and only require the first 3 components to be
2792 specified, in this example "2.3.0". All four
2793 components may still be used if someone wishes to do so.
2799 <sect1 id="f-Version">
2800 <heading><tt>Version</tt></heading>
2803 The version number of a package. The format is:
2804 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2808 The three components here are:
2810 <tag><var>epoch</var></tag>
2813 This is a single (generally small) unsigned integer. It
2814 may be omitted, in which case zero is assumed. If it is
2815 omitted then the <var>upstream_version</var> may not
2820 It is provided to allow mistakes in the version numbers
2821 of older versions of a package, and also a package's
2822 previous version numbering schemes, to be left behind.
2826 <tag><var>upstream_version</var></tag>
2829 This is the main part of the version number. It is
2830 usually the version number of the original ("upstream")
2831 package from which the <file>.deb</file> file has been made,
2832 if this is applicable. Usually this will be in the same
2833 format as that specified by the upstream author(s);
2834 however, it may need to be reformatted to fit into the
2835 package management system's format and comparison
2840 The comparison behavior of the package management system
2841 with respect to the <var>upstream_version</var> is
2842 described below. The <var>upstream_version</var>
2843 portion of the version number is mandatory.
2847 The <var>upstream_version</var> may contain only
2848 alphanumerics<footnote>
2849 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2851 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2852 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
2853 tilde) and should start with a digit. If there is no
2854 <var>debian_revision</var> then hyphens are not allowed;
2855 if there is no <var>epoch</var> then colons are not
2860 <tag><var>debian_revision</var></tag>
2863 This part of the version number specifies the version of
2864 the Debian package based on the upstream version. It
2865 may contain only alphanumerics and the characters
2866 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
2867 tilde) and is compared in the same way as the
2868 <var>upstream_version</var> is.
2872 It is optional; if it isn't present then the
2873 <var>upstream_version</var> may not contain a hyphen.
2874 This format represents the case where a piece of
2875 software was written specifically to be turned into a
2876 Debian package, and so there is only one "debianisation"
2877 of it and therefore no revision indication is required.
2881 It is conventional to restart the
2882 <var>debian_revision</var> at <tt>1</tt> each time the
2883 <var>upstream_version</var> is increased.
2887 The package management system will break the version
2888 number apart at the last hyphen in the string (if there
2889 is one) to determine the <var>upstream_version</var> and
2890 <var>debian_revision</var>. The absence of a
2891 <var>debian_revision</var> is equivalent to a
2892 <var>debian_revision</var> of <tt>0</tt>.
2899 When comparing two version numbers, first the <var>epoch</var>
2900 of each are compared, then the <var>upstream_version</var> if
2901 <var>epoch</var> is equal, and then <var>debian_revision</var>
2902 if <var>upstream_version</var> is also equal.
2903 <var>epoch</var> is compared numerically. The
2904 <var>upstream_version</var> and <var>debian_revision</var>
2905 parts are compared by the package management system using the
2906 following algorithm:
2910 The strings are compared from left to right.
2914 First the initial part of each string consisting entirely of
2915 non-digit characters is determined. These two parts (one of
2916 which may be empty) are compared lexically. If a difference
2917 is found it is returned. The lexical comparison is a
2918 comparison of ASCII values modified so that all the letters
2919 sort earlier than all the non-letters and so that a tilde
2920 sorts before anything, even the end of a part. For example,
2921 the following parts are in sorted order from earliest to
2922 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
2923 <tt>a</tt>.<footnote>
2924 One common use of <tt>~</tt> is for upstream pre-releases.
2925 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
2926 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
2931 Then the initial part of the remainder of each string which
2932 consists entirely of digit characters is determined. The
2933 numerical values of these two parts are compared, and any
2934 difference found is returned as the result of the comparison.
2935 For these purposes an empty string (which can only occur at
2936 the end of one or both version strings being compared) counts
2941 These two steps (comparing and removing initial non-digit
2942 strings and initial digit strings) are repeated until a
2943 difference is found or both strings are exhausted.
2947 Note that the purpose of epochs is to allow us to leave behind
2948 mistakes in version numbering, and to cope with situations
2949 where the version numbering scheme changes. It is
2950 <em>not</em> intended to cope with version numbers containing
2951 strings of letters which the package management system cannot
2952 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
2953 silly orderings (the author of this manual has heard of a
2954 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
2955 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
2956 <tt>2</tt> and so forth).
2960 <sect1 id="f-Description">
2961 <heading><tt>Description</tt></heading>
2964 In a source or binary control file, the <tt>Description</tt>
2965 field contains a description of the binary package, consisting
2966 of two parts, the synopsis or the short description, and the
2967 long description. The field's format is as follows:
2972 Description: <single line synopsis>
2973 <extended description over several lines>
2978 The lines in the extended description can have these formats:
2984 Those starting with a single space are part of a paragraph.
2985 Successive lines of this form will be word-wrapped when
2986 displayed. The leading space will usually be stripped off.
2990 Those starting with two or more spaces. These will be
2991 displayed verbatim. If the display cannot be panned
2992 horizontally, the displaying program will line wrap them "hard"
2993 (i.e., without taking account of word breaks). If it can they
2994 will be allowed to trail off to the right. None, one or two
2995 initial spaces may be deleted, but the number of spaces
2996 deleted from each line will be the same (so that you can have
2997 indenting work correctly, for example).
3001 Those containing a single space followed by a single full stop
3002 character. These are rendered as blank lines. This is the
3003 <em>only</em> way to get a blank line<footnote>
3004 Completely empty lines will not be rendered as blank lines.
3005 Instead, they will cause the parser to think you're starting
3006 a whole new record in the control file, and will therefore
3007 likely abort with an error.
3012 Those containing a space, a full stop and some more characters.
3013 These are for future expansion. Do not use them.
3019 Do not use tab characters. Their effect is not predictable.
3023 See <ref id="descriptions"> for further information on this.
3027 In a <file>.changes</file> file, the <tt>Description</tt> field
3028 contains a summary of the descriptions for the packages being
3033 The part of the field before the first newline is empty;
3034 thereafter each line has the name of a binary package and
3035 the summary description line from that binary package.
3036 Each line is indented by one space.
3041 <sect1 id="f-Distribution">
3042 <heading><tt>Distribution</tt></heading>
3045 In a <file>.changes</file> file or parsed changelog output
3046 this contains the (space-separated) name(s) of the
3047 distribution(s) where this version of the package should
3048 be installed. Valid distributions are determined by the
3049 archive maintainers.<footnote>
3050 Current distribution names are:
3051 <taglist compact="compact">
3052 <tag><em>stable</em></tag>
3054 This is the current "released" version of Debian
3055 GNU/Linux. Once the distribution is
3056 <em>stable</em> only security fixes and other
3057 major bug fixes are allowed. When changes are
3058 made to this distribution, the release number is
3059 increased (for example: 2.2r1 becomes 2.2r2 then
3063 <tag><em>unstable</em></tag>
3065 This distribution value refers to the
3066 <em>developmental</em> part of the Debian
3067 distribution tree. New packages, new upstream
3068 versions of packages and bug fixes go into the
3069 <em>unstable</em> directory tree. Download from
3070 this distribution at your own risk.
3073 <tag><em>testing</em></tag>
3075 This distribution value refers to the
3076 <em>testing</em> part of the Debian distribution
3077 tree. It receives its packages from the
3078 unstable distribution after a short time lag to
3079 ensure that there are no major issues with the
3080 unstable packages. It is less prone to breakage
3081 than unstable, but still risky. It is not
3082 possible to upload packages directly to
3086 <tag><em>frozen</em></tag>
3088 From time to time, the <em>testing</em>
3089 distribution enters a state of "code-freeze" in
3090 anticipation of release as a <em>stable</em>
3091 version. During this period of testing only
3092 fixes for existing or newly-discovered bugs will
3093 be allowed. The exact details of this stage are
3094 determined by the Release Manager.
3097 <tag><em>experimental</em></tag>
3099 The packages with this distribution value are
3100 deemed by their maintainers to be high
3101 risk. Oftentimes they represent early beta or
3102 developmental packages from various sources that
3103 the maintainers want people to try, but are not
3104 ready to be a part of the other parts of the
3105 Debian distribution tree. Download at your own
3111 You should list <em>all</em> distributions that the
3112 package should be installed into.
3116 More information is available in the Debian Developer's
3117 Reference, section "The Debian archive".
3124 <heading><tt>Date</tt></heading>
3127 This field includes the date the package was built or last edited.
3131 The value of this field is usually extracted from the
3132 <file>debian/changelog</file> file - see
3133 <ref id="dpkgchangelog">).
3137 <sect1 id="f-Format">
3138 <heading><tt>Format</tt></heading>
3141 This field specifies a format revision for the file.
3142 The most current format described in the Policy Manual
3143 is version <strong>1.5</strong>. The syntax of the
3144 format value is the same as that of a package version
3145 number except that no epoch or Debian revision is allowed
3146 - see <ref id="f-Version">.
3150 <sect1 id="f-Urgency">
3151 <heading><tt>Urgency</tt></heading>
3154 This is a description of how important it is to upgrade to
3155 this version from previous ones. It consists of a single
3156 keyword taking one of the values <tt>low</tt>,
3157 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3158 <tt>critical</tt><footnote>
3159 Other urgency values are supported with configuration
3160 changes in the archive software but are not used in Debian.
3161 The urgency affects how quickly a package will be considered
3162 for inclusion into the <tt>testing</tt> distribution and
3163 gives an indication of the importance of any fixes included
3164 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3165 treated as synonymous.
3166 </footnote> (not case-sensitive) followed by an optional
3167 commentary (separated by a space) which is usually in
3168 parentheses. For example:
3171 Urgency: low (HIGH for users of diversions)
3177 The value of this field is usually extracted from the
3178 <file>debian/changelog</file> file - see
3179 <ref id="dpkgchangelog">.
3183 <sect1 id="f-Changes">
3184 <heading><tt>Changes</tt></heading>
3187 This field contains the human-readable changes data, describing
3188 the differences between the last version and the current one.
3192 There should be nothing in this field before the first
3193 newline; all the subsequent lines must be indented by at
3194 least one space; blank lines must be represented by a line
3195 consisting only of a space and a full stop.
3199 The value of this field is usually extracted from the
3200 <file>debian/changelog</file> file - see
3201 <ref id="dpkgchangelog">).
3205 Each version's change information should be preceded by a
3206 "title" line giving at least the version, distribution(s)
3207 and urgency, in a human-readable way.
3211 If data from several versions is being returned the entry
3212 for the most recent version should be returned first, and
3213 entries should be separated by the representation of a
3214 blank line (the "title" line may also be followed by the
3215 representation of blank line).
3219 <sect1 id="f-Binary">
3220 <heading><tt>Binary</tt></heading>
3223 This field is a list of binary packages.
3227 When it appears in the <file>.dsc</file> file it is the list
3228 of binary packages which a source package can produce. It
3229 does not necessarily produce all of these binary packages
3230 for every architecture. The source control file doesn't
3231 contain details of which architectures are appropriate for
3232 which of the binary packages.
3236 When it appears in a <file>.changes</file> file it lists the
3237 names of the binary packages actually being uploaded.
3241 The syntax is a list of binary packages separated by
3243 A space after each comma is conventional.
3244 </footnote>. Currently the packages must be separated using
3245 only spaces in the <file>.changes</file> file.
3249 <sect1 id="f-Installed-Size">
3250 <heading><tt>Installed-Size</tt></heading>
3253 This field appears in the control files of binary
3254 packages, and in the <file>Packages</file> files. It gives
3255 the total amount of disk space required to install the
3260 The disk space is represented in kilobytes as a simple
3265 <sect1 id="f-Files">
3266 <heading><tt>Files</tt></heading>
3269 This field contains a list of files with information about
3270 each one. The exact information and syntax varies with
3271 the context. In all cases the part of the field
3272 contents on the same line as the field name is empty. The
3273 remainder of the field is one line per file, each line
3274 being indented by one space and containing a number of
3275 sub-fields separated by spaces.
3279 In the <file>.dsc</file> file, each line contains the MD5
3280 checksum, size and filename of the tar file and (if applicable)
3281 diff file which make up the remainder of the source
3283 That is, the parts which are not the <tt>.dsc</tt>.
3285 The exact forms of the filenames are described
3286 in <ref id="pkg-sourcearchives">.
3290 In the <file>.changes</file> file this contains one line per
3291 file being uploaded. Each line contains the MD5 checksum,
3292 size, section and priority and the filename.
3293 The <qref id="f-Section">section</qref>
3294 and <qref id="f-Priority">priority</qref>
3295 are the values of the corresponding fields in
3296 the main source control file. If no section or priority is
3297 specified then <tt>-</tt> should be used, though section
3298 and priority values must be specified for new packages to
3299 be installed properly.
3303 The special value <tt>byhand</tt> for the section in a
3304 <tt>.changes</tt> file indicates that the file in question
3305 is not an ordinary package file and must by installed by
3306 hand by the distribution maintainers. If the section is
3307 <tt>byhand</tt> the priority should be <tt>-</tt>.
3311 If a new Debian revision of a package is being shipped and
3312 no new original source archive is being distributed the
3313 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3314 entry for the original source archive
3315 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
3316 but the <file>.changes</file> file should leave it out. In
3317 this case the original source archive on the distribution
3318 site must match exactly, byte-for-byte, the original
3319 source archive which was used to generate the
3320 <file>.dsc</file> file and diff which are being uploaded.</p>
3323 <sect1 id="f-Closes">
3324 <heading><tt>Closes</tt></heading>
3327 A space-separated list of bug report numbers that the upload
3328 governed by the .changes file closes.
3332 <sect1 id="f-Homepage">
3333 <heading><tt>Homepage</tt></heading>
3336 The URL of the web site for this package, preferably (when
3337 applicable) the site from which the original source can be
3338 obtained and any additional upstream documentation or
3339 information may be found. The content of this field is a
3340 simple URL without any surrounding characters such as
3348 <heading>User-defined fields</heading>
3351 Additional user-defined fields may be added to the
3352 source package control file. Such fields will be
3353 ignored, and not copied to (for example) binary or
3354 source package control files or upload control files.
3358 If you wish to add additional unsupported fields to
3359 these output files you should use the mechanism
3364 Fields in the main source control information file with
3365 names starting <tt>X</tt>, followed by one or more of
3366 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3367 be copied to the output files. Only the part of the
3368 field name after the hyphen will be used in the output
3369 file. Where the letter <tt>B</tt> is used the field
3370 will appear in binary package control files, where the
3371 letter <tt>S</tt> is used in source package control
3372 files and where <tt>C</tt> is used in upload control
3373 (<tt>.changes</tt>) files.
3377 For example, if the main source information control file
3380 XBS-Comment: I stand between the candle and the star.
3382 then the binary and source package control files will contain the
3385 Comment: I stand between the candle and the star.
3394 <chapt id="maintainerscripts">
3395 <heading>Package maintainer scripts and installation procedure</heading>
3398 <heading>Introduction to package maintainer scripts</heading>
3401 It is possible to supply scripts as part of a package which
3402 the package management system will run for you when your
3403 package is installed, upgraded or removed.
3407 These scripts are the files <prgn>preinst</prgn>,
3408 <prgn>postinst</prgn>, <prgn>prerm</prgn> and
3409 <prgn>postrm</prgn> in the control area of the package.
3410 They must be proper executable files; if they are scripts
3411 (which is recommended), they must start with the usual
3412 <tt>#!</tt> convention. They should be readable and
3413 executable by anyone, and must not be world-writable.
3417 The package management system looks at the exit status from
3418 these scripts. It is important that they exit with a
3419 non-zero status if there is an error, so that the package
3420 management system can stop its processing. For shell
3421 scripts this means that you <em>almost always</em> need to
3422 use <tt>set -e</tt> (this is usually true when writing shell
3423 scripts, in fact). It is also important, of course, that
3424 they don't exit with a non-zero status if everything went
3429 Additionally, packages interacting with users using
3430 <tt>debconf</tt> in the <prgn>postinst</prgn> script should
3431 install a <prgn>config</prgn> script in the control area,
3432 see <ref id="maintscriptprompt"> for details.
3436 When a package is upgraded a combination of the scripts from
3437 the old and new packages is called during the upgrade
3438 procedure. If your scripts are going to be at all
3439 complicated you need to be aware of this, and may need to
3440 check the arguments to your scripts.
3444 Broadly speaking the <prgn>preinst</prgn> is called before
3445 (a particular version of) a package is installed, and the
3446 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3447 before (a version of) a package is removed and the
3448 <prgn>postrm</prgn> afterwards.
3452 Programs called from maintainer scripts should not normally
3453 have a path prepended to them. Before installation is
3454 started, the package management system checks to see if the
3455 programs <prgn>ldconfig</prgn>,
3456 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3457 and <prgn>update-rc.d</prgn> can be found via the
3458 <tt>PATH</tt> environment variable. Those programs, and any
3459 other program that one would expect to be in the
3460 <tt>PATH</tt>, should thus be invoked without an absolute
3461 pathname. Maintainer scripts should also not reset the
3462 <tt>PATH</tt>, though they might choose to modify it by
3463 prepending or appending package-specific directories. These
3464 considerations really apply to all shell scripts.</p>
3467 <sect id="idempotency">
3468 <heading>Maintainer scripts idempotency</heading>
3471 It is necessary for the error recovery procedures that the
3472 scripts be idempotent. This means that if it is run
3473 successfully, and then it is called again, it doesn't bomb
3474 out or cause any harm, but just ensures that everything is
3475 the way it ought to be. If the first call failed, or
3476 aborted half way through for some reason, the second call
3477 should merely do the things that were left undone the first
3478 time, if any, and exit with a success status if everything
3480 This is so that if an error occurs, the user interrupts
3481 <prgn>dpkg</prgn> or some other unforeseen circumstance
3482 happens you don't leave the user with a badly-broken
3483 package when <prgn>dpkg</prgn> attempts to repeat the
3489 <sect id="controllingterminal">
3490 <heading>Controlling terminal for maintainer scripts</heading>
3493 The maintainer scripts are guaranteed to run with a
3494 controlling terminal and can interact with the user.
3495 Because these scripts may be executed with standard output
3496 redirected into a pipe for logging purposes, Perl scripts
3497 should set unbuffered output by setting <tt>$|=1</tt> so
3498 that the output is printed immediately rather than being
3502 <sect id="exitstatus">
3503 <heading>Exit status</heading>
3506 Each script must return a zero exit status for
3507 success, or a nonzero one for failure, since the package
3508 management system looks for the exit status of these scripts
3509 and determines what action to take next based on that datum.
3513 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3518 <list compact="compact">
3520 <var>new-preinst</var> <tt>install</tt>
3523 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3526 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3529 <var>old-preinst</var> <tt>abort-upgrade</tt>
3530 <var>new-version</var>
3535 <list compact="compact">
3537 <var>postinst</var> <tt>configure</tt>
3538 <var>most-recently-configured-version</var>
3541 <var>old-postinst</var> <tt>abort-upgrade</tt>
3542 <var>new-version</var>
3545 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3546 <tt>in-favour</tt> <var>package</var>
3547 <var>new-version</var>
3550 <var>postinst</var> <tt>abort-remove</tt>
3553 <var>deconfigured's-postinst</var>
3554 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3555 <var>failed-install-package</var> <var>version</var>
3556 [<tt>removing</tt> <var>conflicting-package</var>
3562 <list compact="compact">
3564 <var>prerm</var> <tt>remove</tt>
3567 <var>old-prerm</var> <tt>upgrade</tt>
3568 <var>new-version</var>
3571 <var>new-prerm</var> <tt>failed-upgrade</tt>
3572 <var>old-version</var>
3575 <var>conflictor's-prerm</var> <tt>remove</tt>
3576 <tt>in-favour</tt> <var>package</var>
3577 <var>new-version</var>
3580 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3581 <tt>in-favour</tt> <var>package-being-installed</var>
3582 <var>version</var> [<tt>removing</tt>
3583 <var>conflicting-package</var>
3589 <list compact="compact">
3591 <var>postrm</var> <tt>remove</tt>
3594 <var>postrm</var> <tt>purge</tt>
3597 <var>old-postrm</var> <tt>upgrade</tt>
3598 <var>new-version</var>
3601 <var>new-postrm</var> <tt>failed-upgrade</tt>
3602 <var>old-version</var>
3605 <var>new-postrm</var> <tt>abort-install</tt>
3608 <var>new-postrm</var> <tt>abort-install</tt>
3609 <var>old-version</var>
3612 <var>new-postrm</var> <tt>abort-upgrade</tt>
3613 <var>old-version</var>
3616 <var>disappearer's-postrm</var> <tt>disappear</tt>
3617 <var>overwriter</var>
3618 <var>overwriter-version</var>
3624 <sect id="unpackphase">
3625 <heading>Details of unpack phase of installation or upgrade</heading>
3628 The procedure on installation/upgrade/overwrite/disappear
3629 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3630 stage of <tt>dpkg --install</tt>) is as follows. In each
3631 case, if a major error occurs (unless listed below) the
3632 actions are, in general, run backwards - this means that the
3633 maintainer scripts are run with different arguments in
3634 reverse order. These are the "error unwind" calls listed
3641 If a version of the package is already installed, call
3642 <example compact="compact">
3643 <var>old-prerm</var> upgrade <var>new-version</var>
3647 If the script runs but exits with a non-zero
3648 exit status, <prgn>dpkg</prgn> will attempt:
3649 <example compact="compact">
3650 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3652 If this works, the upgrade continues. If this
3653 does not work, the error unwind:
3654 <example compact="compact">
3655 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3657 If this works, then the old-version is
3658 "Installed", if not, the old version is in a
3659 "Failed-Config" state.
3665 If a "conflicting" package is being removed at the same time,
3666 or if any package will be broken (due to <tt>Breaks</tt>):
3669 If <tt>--auto-deconfigure</tt> is
3670 specified, call, for each package to be deconfigured
3671 due to <tt>Breaks</tt>:
3672 <example compact="compact">
3673 <var>deconfigured's-prerm</var> deconfigure \
3674 in-favour <var>package-being-installed</var> <var>version</var>
3677 <example compact="compact">
3678 <var>deconfigured's-postinst</var> abort-deconfigure \
3679 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3681 The deconfigured packages are marked as
3682 requiring configuration, so that if
3683 <tt>--install</tt> is used they will be
3684 configured again if possible.
3687 If any packages depended on a conflicting
3688 package being removed and <tt>--auto-deconfigure</tt> is
3689 specified, call, for each such package:
3690 <example compact="compact">
3691 <var>deconfigured's-prerm</var> deconfigure \
3692 in-favour <var>package-being-installed</var> <var>version</var> \
3693 removing <var>conflicting-package</var> <var>version</var>
3696 <example compact="compact">
3697 <var>deconfigured's-postinst</var> abort-deconfigure \
3698 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3699 removing <var>conflicting-package</var> <var>version</var>
3701 The deconfigured packages are marked as
3702 requiring configuration, so that if
3703 <tt>--install</tt> is used they will be
3704 configured again if possible.
3707 To prepare for removal of each conflicting package, call:
3708 <example compact="compact">
3709 <var>conflictor's-prerm</var> remove \
3710 in-favour <var>package</var> <var>new-version</var>
3713 <example compact="compact">
3714 <var>conflictor's-postinst</var> abort-remove \
3715 in-favour <var>package</var> <var>new-version</var>
3724 If the package is being upgraded, call:
3725 <example compact="compact">
3726 <var>new-preinst</var> upgrade <var>old-version</var>
3728 If this fails, we call:
3730 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3737 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3739 is called. If this works, then the old version
3740 is in an "Installed" state, or else it is left
3741 in an "Unpacked" state.
3746 If it fails, then the old version is left
3747 in an "Half-Installed" state.
3754 Otherwise, if the package had some configuration
3755 files from a previous version installed (i.e., it
3756 is in the "configuration files only" state):
3757 <example compact="compact">
3758 <var>new-preinst</var> install <var>old-version</var>
3762 <var>new-postrm</var> abort-install <var>old-version</var>
3764 If this fails, the package is left in a
3765 "Half-Installed" state, which requires a
3766 reinstall. If it works, the packages is left in
3767 a "Config Files" state.
3770 Otherwise (i.e., the package was completely purged):
3771 <example compact="compact">
3772 <var>new-preinst</var> install
3775 <example compact="compact">
3776 <var>new-postrm</var> abort-install
3778 If the error-unwind fails, the package is in a
3779 "Half Installed" phase, and requires a
3780 reinstall. If the error unwind works, the
3781 package is in a not installed state.
3788 The new package's files are unpacked, overwriting any
3789 that may be on the system already, for example any
3790 from the old version of the same package or from
3791 another package. Backups of the old files are kept
3792 temporarily, and if anything goes wrong the package
3793 management system will attempt to put them back as
3794 part of the error unwind.
3798 It is an error for a package to contain files which
3799 are on the system in another package, unless
3800 <tt>Replaces</tt> is used (see <ref id="replaces">).
3802 The following paragraph is not currently the case:
3803 Currently the <tt>- - force-overwrite</tt> flag is
3804 enabled, downgrading it to a warning, but this may not
3810 It is a more serious error for a package to contain a
3811 plain file or other kind of non-directory where another
3812 package has a directory (again, unless
3813 <tt>Replaces</tt> is used). This error can be
3814 overridden if desired using
3815 <tt>--force-overwrite-dir</tt>, but this is not
3820 Packages which overwrite each other's files produce
3821 behavior which, though deterministic, is hard for the
3822 system administrator to understand. It can easily
3823 lead to "missing" programs if, for example, a package
3824 is installed which overwrites a file from another
3825 package, and is then removed again.<footnote>
3826 Part of the problem is due to what is arguably a
3827 bug in <prgn>dpkg</prgn>.
3832 A directory will never be replaced by a symbolic link
3833 to a directory or vice versa; instead, the existing
3834 state (symlink or not) will be left alone and
3835 <prgn>dpkg</prgn> will follow the symlink if there is
3844 If the package is being upgraded, call
3845 <example compact="compact">
3846 <var>old-postrm</var> upgrade <var>new-version</var>
3850 If this fails, <prgn>dpkg</prgn> will attempt:
3851 <example compact="compact">
3852 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3854 If this works, installation continues. If not,
3856 <example compact="compact">
3857 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3859 If this fails, the old version is left in an
3860 "Half Installed" state. If it works, dpkg now
3862 <example compact="compact">
3863 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3865 If this fails, the old version is left in an
3866 "Half Installed" state. If it works, dpkg now
3868 <example compact="compact">
3869 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3871 If this fails, the old version is in an
3878 This is the point of no return - if
3879 <prgn>dpkg</prgn> gets this far, it won't back off
3880 past this point if an error occurs. This will
3881 leave the package in a fairly bad state, which
3882 will require a successful re-installation to clear
3883 up, but it's when <prgn>dpkg</prgn> starts doing
3884 things that are irreversible.
3889 Any files which were in the old version of the package
3890 but not in the new are removed.
3894 The new file list replaces the old.
3898 The new maintainer scripts replace the old.
3902 Any packages all of whose files have been overwritten
3903 during the installation, and which aren't required for
3904 dependencies, are considered to have been removed.
3905 For each such package
3908 <prgn>dpkg</prgn> calls:
3909 <example compact="compact">
3910 <var>disappearer's-postrm</var> disappear \
3911 <var>overwriter</var> <var>overwriter-version</var>
3915 The package's maintainer scripts are removed.
3918 It is noted in the status database as being in a
3919 sane state, namely not installed (any conffiles
3920 it may have are ignored, rather than being
3921 removed by <prgn>dpkg</prgn>). Note that
3922 disappearing packages do not have their prerm
3923 called, because <prgn>dpkg</prgn> doesn't know
3924 in advance that the package is going to
3931 Any files in the package we're unpacking that are also
3932 listed in the file lists of other packages are removed
3933 from those lists. (This will lobotomize the file list
3934 of the "conflicting" package if there is one.)
3938 The backup files made during installation, above, are
3944 The new package's status is now sane, and recorded as
3949 Here is another point of no return - if the
3950 conflicting package's removal fails we do not unwind
3951 the rest of the installation; the conflicting package
3952 is left in a half-removed limbo.
3957 If there was a conflicting package we go and do the
3958 removal actions (described below), starting with the
3959 removal of the conflicting package's files (any that
3960 are also in the package being installed have already
3961 been removed from the conflicting package's file list,
3962 and so do not get removed now).
3968 <sect id="configdetails"><heading>Details of configuration</heading>
3971 When we configure a package (this happens with <tt>dpkg
3972 --install</tt> and <tt>dpkg --configure</tt>), we first
3973 update any <tt>conffile</tt>s and then call:
3974 <example compact="compact">
3975 <var>postinst</var> configure <var>most-recently-configured-version</var>
3980 No attempt is made to unwind after errors during
3981 configuration. If the configuration fails, the package is in
3982 a "Failed Config" state, and an error message is generated.
3986 If there is no most recently configured version
3987 <prgn>dpkg</prgn> will pass a null argument.
3990 Historical note: Truly ancient (pre-1997) versions of
3991 <prgn>dpkg</prgn> passed <tt><unknown></tt>
3992 (including the angle brackets) in this case. Even older
3993 ones did not pass a second argument at all, under any
3994 circumstance. Note that upgrades using such an old dpkg
3995 version are unlikely to work for other reasons, even if
3996 this old argument behavior is handled by your postinst script.
4002 <sect id="removedetails"><heading>Details of removal and/or
4003 configuration purging</heading>
4009 <example compact="compact">
4010 <var>prerm</var> remove
4014 If prerm fails during replacement due to conflict
4016 <var>conflictor's-postinst</var> abort-remove \
4017 in-favour <var>package</var> <var>new-version</var>
4021 <var>postinst</var> abort-remove
4025 If this fails, the package is in a "Failed-Config"
4026 state, or else it remains "Installed".
4030 The package's files are removed (except <tt>conffile</tt>s).
4033 <example compact="compact">
4034 <var>postrm</var> remove
4038 If it fails, there's no error unwind, and the package is in
4039 an "Half-Installed" state.
4044 All the maintainer scripts except the <prgn>postrm</prgn>
4049 If we aren't purging the package we stop here. Note
4050 that packages which have no <prgn>postrm</prgn> and no
4051 <tt>conffile</tt>s are automatically purged when
4052 removed, as there is no difference except for the
4053 <prgn>dpkg</prgn> status.
4057 The <tt>conffile</tt>s and any backup files
4058 (<tt>~</tt>-files, <tt>#*#</tt> files,
4059 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4064 <example compact="compact">
4065 <var>postrm</var> purge
4069 If this fails, the package remains in a "Config-Files"
4074 The package's file list is removed.
4083 <chapt id="relationships">
4084 <heading>Declaring relationships between packages</heading>
4086 <sect id="depsyntax">
4087 <heading>Syntax of relationship fields</heading>
4090 These fields all have a uniform syntax. They are a list of
4091 package names separated by commas.
4095 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4096 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4097 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4098 control file fields of the package, which declare
4099 dependencies on other packages, the package names listed may
4100 also include lists of alternative package names, separated
4101 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4102 if any one of the alternative packages is installed, that
4103 part of the dependency is considered to be satisfied.
4107 All of the fields except for <tt>Provides</tt> may restrict
4108 their applicability to particular versions of each named
4109 package. This is done in parentheses after each individual
4110 package name; the parentheses should contain a relation from
4111 the list below followed by a version number, in the format
4112 described in <ref id="f-Version">.
4116 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4117 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4118 strictly earlier, earlier or equal, exactly equal, later or
4119 equal and strictly later, respectively. The deprecated
4120 forms <tt><</tt> and <tt>></tt> were used to mean
4121 earlier/later or equal, rather than strictly earlier/later,
4122 so they should not appear in new packages (though
4123 <prgn>dpkg</prgn> still supports them).
4127 Whitespace may appear at any point in the version
4128 specification subject to the rules in <ref
4129 id="controlsyntax">, and must appear where it's necessary to
4130 disambiguate; it is not otherwise significant. All of the
4131 relationship fields may span multiple lines. For
4132 consistency and in case of future changes to
4133 <prgn>dpkg</prgn> it is recommended that a single space be
4134 used after a version relationship and before a version
4135 number; it is also conventional to put a single space after
4136 each comma, on either side of each vertical bar, and before
4137 each open parenthesis. When wrapping a relationship field, it
4138 is conventional to do so after a comma and before the space
4139 following that comma.
4143 For example, a list of dependencies might appear as:
4144 <example compact="compact">
4147 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4152 All fields that specify build-time relationships
4153 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4154 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
4155 may be restricted to a certain set of architectures. This
4156 is indicated in brackets after each individual package name and
4157 the optional version specification. The brackets enclose a
4158 list of Debian architecture names separated by whitespace.
4159 Exclamation marks may be prepended to each of the names.
4160 (It is not permitted for some names to be prepended with
4161 exclamation marks while others aren't.) If the current Debian
4162 host architecture is not in this list and there are no
4163 exclamation marks in the list, or it is in the list with a
4164 prepended exclamation mark, the package name and the
4165 associated version specification are ignored completely for
4166 the purposes of defining the relationships.
4171 <example compact="compact">
4173 Build-Depends-Indep: texinfo
4174 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4175 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4180 Note that the binary package relationship fields such as
4181 <tt>Depends</tt> appear in one of the binary package
4182 sections of the control file, whereas the build-time
4183 relationships such as <tt>Build-Depends</tt> appear in the
4184 source package section of the control file (which is the
4189 <sect id="binarydeps">
4190 <heading>Binary Dependencies - <tt>Depends</tt>,
4191 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4192 <tt>Pre-Depends</tt>
4196 Packages can declare in their control file that they have
4197 certain relationships to other packages - for example, that
4198 they may not be installed at the same time as certain other
4199 packages, and/or that they depend on the presence of others.
4203 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4204 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4205 <tt>Breaks</tt> and <tt>Conflicts</tt> control file fields.
4209 These seven fields are used to declare a dependency
4210 relationship by one package on another. Except for
4211 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4212 depending (binary) package's control file.
4213 (<tt>Enhances</tt> appears in the recommending package's
4214 control file, and <tt>Breaks</tt> appears in the version of
4215 depended-on package which causes the named package to
4220 A <tt>Depends</tt> field takes effect <em>only</em> when a
4221 package is to be configured. It does not prevent a package
4222 being on the system in an unconfigured state while its
4223 dependencies are unsatisfied, and it is possible to replace
4224 a package whose dependencies are satisfied and which is
4225 properly installed with a different version whose
4226 dependencies are not and cannot be satisfied; when this is
4227 done the depending package will be left unconfigured (since
4228 attempts to configure it will give errors) and will not
4229 function properly. If it is necessary, a
4230 <tt>Pre-Depends</tt> field can be used, which has a partial
4231 effect even when a package is being unpacked, as explained
4232 in detail below. (The other three dependency fields,
4233 <tt>Recommends</tt>, <tt>Suggests</tt> and
4234 <tt>Enhances</tt>, are only used by the various front-ends
4235 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4236 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4240 For this reason packages in an installation run are usually
4241 all unpacked first and all configured later; this gives
4242 later versions of packages with dependencies on later
4243 versions of other packages the opportunity to have their
4244 dependencies satisfied.
4248 In case of circular dependencies, since installation or
4249 removal order honoring the dependency order can't be
4250 established, dependency loops are broken at some point
4251 (based on rules below), and some packages may not be able to
4252 rely on their dependencies being present when being
4253 installed or removed, depending on which side of the break
4254 of the circular dependency loop they happen to be on. If one
4255 of the packages in the loop has no postinst script, then the
4256 cycle will be broken at that package, so as to ensure that
4257 all postinst scripts run with the dependencies properly
4258 configured if this is possible. Otherwise the breaking point
4263 The <tt>Depends</tt> field thus allows package maintainers
4264 to impose an order in which packages should be configured.
4268 The meaning of the five dependency fields is as follows:
4270 <tag><tt>Depends</tt></tag>
4273 This declares an absolute dependency. A package will
4274 not be configured unless all of the packages listed in
4275 its <tt>Depends</tt> field have been correctly
4280 The <tt>Depends</tt> field should be used if the
4281 depended-on package is required for the depending
4282 package to provide a significant amount of
4287 The <tt>Depends</tt> field should also be used if the
4288 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4289 <prgn>postrm</prgn> scripts require the package to be
4290 present in order to run. Note, however, that the
4291 <prgn>postrm</prgn> cannot rely on any non-essential
4292 packages to be present during the <tt>purge</tt>
4296 <tag><tt>Recommends</tt></tag>
4299 This declares a strong, but not absolute, dependency.
4303 The <tt>Recommends</tt> field should list packages
4304 that would be found together with this one in all but
4305 unusual installations.
4309 <tag><tt>Suggests</tt></tag>
4311 This is used to declare that one package may be more
4312 useful with one or more others. Using this field
4313 tells the packaging system and the user that the
4314 listed packages are related to this one and can
4315 perhaps enhance its usefulness, but that installing
4316 this one without them is perfectly reasonable.
4319 <tag><tt>Enhances</tt></tag>
4321 This field is similar to Suggests but works in the
4322 opposite direction. It is used to declare that a
4323 package can enhance the functionality of another
4327 <tag><tt>Pre-Depends</tt></tag>
4330 This field is like <tt>Depends</tt>, except that it
4331 also forces <prgn>dpkg</prgn> to complete installation
4332 of the packages named before even starting the
4333 installation of the package which declares the
4334 pre-dependency, as follows:
4338 When a package declaring a pre-dependency is about to
4339 be <em>unpacked</em> the pre-dependency can be
4340 satisfied if the depended-on package is either fully
4341 configured, <em>or even if</em> the depended-on
4342 package(s) are only unpacked or half-configured,
4343 provided that they have been configured correctly at
4344 some point in the past (and not removed or partially
4345 removed since). In this case, both the
4346 previously-configured and currently unpacked or
4347 half-configured versions must satisfy any version
4348 clause in the <tt>Pre-Depends</tt> field.
4352 When the package declaring a pre-dependency is about
4353 to be <em>configured</em>, the pre-dependency will be
4354 treated as a normal <tt>Depends</tt>, that is, it will
4355 be considered satisfied only if the depended-on
4356 package has been correctly configured.
4360 <tt>Pre-Depends</tt> should be used sparingly,
4361 preferably only by packages whose premature upgrade or
4362 installation would hamper the ability of the system to
4363 continue with any upgrade that might be in progress.
4367 <tt>Pre-Depends</tt> are also required if the
4368 <prgn>preinst</prgn> script depends on the named
4369 package. It is best to avoid this situation if
4377 When selecting which level of dependency to use you should
4378 consider how important the depended-on package is to the
4379 functionality of the one declaring the dependency. Some
4380 packages are composed of components of varying degrees of
4381 importance. Such a package should list using
4382 <tt>Depends</tt> the package(s) which are required by the
4383 more important components. The other components'
4384 requirements may be mentioned as Suggestions or
4385 Recommendations, as appropriate to the components' relative
4391 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4394 Using <tt>Breaks</tt> may cause problems for upgrades from older
4395 versions of Debian and should not be used until the stable
4396 release of Debian supports <tt>Breaks</tt>.
4400 When one binary package declares that it breaks another,
4401 <prgn>dpkg</prgn> will refuse to allow the package which
4402 declares <tt>Breaks</tt> be installed unless the broken
4403 package is deconfigured first, and it will refuse to
4404 allow the broken package to be reconfigured.
4408 A package will not be regarded as causing breakage merely
4409 because its configuration files are still installed; it must
4410 be at least half-installed.
4414 A special exception is made for packages which declare that
4415 they break their own package name or a virtual package which
4416 they provide (see below): this does not count as a real
4421 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4422 version clause; such a <tt>Breaks</tt> is introduced in the
4423 version of an (implicit or explicit) dependency which
4424 violates an assumption or reveals a bug in earlier versions
4425 of the broken package. This use of <tt>Breaks</tt> will
4426 inform higher-level package management tools that broken
4427 package must be upgraded before the new one.
4431 If the breaking package also overwrites some files from the
4432 older package, it should use <tt>Replaces</tt> (not
4433 <tt>Conflicts</tt>) to ensure this goes smoothly.
4437 <sect id="conflicts">
4438 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4441 When one binary package declares a conflict with another
4442 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4443 refuse to allow them to be installed on the system at the
4448 If one package is to be installed, the other must be removed
4449 first - if the package being installed is marked as
4450 replacing (see <ref id="replaces">) the one on the system,
4451 or the one on the system is marked as deselected, or both
4452 packages are marked <tt>Essential</tt>, then
4453 <prgn>dpkg</prgn> will automatically remove the package
4454 which is causing the conflict, otherwise it will halt the
4455 installation of the new package with an error. This
4456 mechanism is specifically designed to produce an error when
4457 the installed package is <tt>Essential</tt>, but the new
4462 A package will not cause a conflict merely because its
4463 configuration files are still installed; it must be at least
4468 A special exception is made for packages which declare a
4469 conflict with their own package name, or with a virtual
4470 package which they provide (see below): this does not
4471 prevent their installation, and allows a package to conflict
4472 with others providing a replacement for it. You use this
4473 feature when you want the package in question to be the only
4474 package providing some feature.
4478 A <tt>Conflicts</tt> entry should almost never have an
4479 "earlier than" version clause. This would prevent
4480 <prgn>dpkg</prgn> from upgrading or installing the package
4481 which declared such a conflict until the upgrade or removal
4482 of the conflicted-with package had been completed. Instead,
4483 <tt>Breaks</tt> may be used (once <tt>Breaks</tt> is supported
4484 by the stable release of Debian).
4488 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4492 As well as the names of actual ("concrete") packages, the
4493 package relationship fields <tt>Depends</tt>,
4494 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4495 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4496 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4497 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4498 may mention "virtual packages".
4502 A <em>virtual package</em> is one which appears in the
4503 <tt>Provides</tt> control file field of another package.
4504 The effect is as if the package(s) which provide a
4505 particular virtual package name had been listed by name
4506 everywhere the virtual package name appears. (See also <ref
4511 If there are both concrete and virtual packages of the same
4512 name, then the dependency may be satisfied (or the conflict
4513 caused) by either the concrete package with the name in
4514 question or any other concrete package which provides the
4515 virtual package with the name in question. This is so that,
4516 for example, supposing we have
4517 <example compact="compact">
4520 </example> and someone else releases an enhanced version of
4521 the <tt>bar</tt> package they can say:
4522 <example compact="compact">
4526 and the <tt>bar-plus</tt> package will now also satisfy the
4527 dependency for the <tt>foo</tt> package.
4531 If a relationship field has a version number attached
4532 then only real packages will be considered to see whether
4533 the relationship is satisfied (or the prohibition violated,
4534 for a conflict or breakage) - it is assumed that a real
4535 package which provides the virtual package is not of the
4536 "right" version. So, a <tt>Provides</tt> field may not
4537 contain version numbers, and the version number of the
4538 concrete package which provides a particular virtual package
4539 will not be looked at when considering a dependency on or
4540 conflict with the virtual package name.
4544 It is likely that the ability will be added in a future
4545 release of <prgn>dpkg</prgn> to specify a version number for
4546 each virtual package it provides. This feature is not yet
4547 present, however, and is expected to be used only
4552 If you want to specify which of a set of real packages
4553 should be the default to satisfy a particular dependency on
4554 a virtual package, you should list the real package as an
4555 alternative before the virtual one.
4560 <sect id="replaces"><heading>Overwriting files and replacing
4561 packages - <tt>Replaces</tt></heading>
4564 Packages can declare in their control file that they should
4565 overwrite files in certain other packages, or completely
4566 replace other packages. The <tt>Replaces</tt> control file
4567 field has these two distinct purposes.
4570 <sect1><heading>Overwriting files in other packages</heading>
4573 Firstly, as mentioned before, it is usually an error for a
4574 package to contain files which are on the system in
4579 However, if the overwriting package declares that it
4580 <tt>Replaces</tt> the one containing the file being
4581 overwritten, then <prgn>dpkg</prgn> will replace the file
4582 from the old package with that from the new. The file
4583 will no longer be listed as "owned" by the old package.
4587 If a package is completely replaced in this way, so that
4588 <prgn>dpkg</prgn> does not know of any files it still
4589 contains, it is considered to have "disappeared". It will
4590 be marked as not wanted on the system (selected for
4591 removal) and not installed. Any <tt>conffile</tt>s
4592 details noted for the package will be ignored, as they
4593 will have been taken over by the overwriting package. The
4594 package's <prgn>postrm</prgn> script will be run with a
4595 special argument to allow the package to do any final
4596 cleanup required. See <ref id="mscriptsinstact">.
4599 Replaces is a one way relationship -- you have to
4600 install the replacing package after the replaced
4607 For this usage of <tt>Replaces</tt>, virtual packages (see
4608 <ref id="virtual">) are not considered when looking at a
4609 <tt>Replaces</tt> field - the packages declared as being
4610 replaced must be mentioned by their real names.
4614 Furthermore, this usage of <tt>Replaces</tt> only takes
4615 effect when both packages are at least partially on the
4616 system at once, so that it can only happen if they do not
4617 conflict or if the conflict has been overridden.
4622 <sect1><heading>Replacing whole packages, forcing their
4626 Secondly, <tt>Replaces</tt> allows the packaging system to
4627 resolve which package should be removed when there is a
4628 conflict - see <ref id="conflicts">. This usage only
4629 takes effect when the two packages <em>do</em> conflict,
4630 so that the two usages of this field do not interfere with
4635 In this situation, the package declared as being replaced
4636 can be a virtual package, so for example, all mail
4637 transport agents (MTAs) would have the following fields in
4638 their control files:
4639 <example compact="compact">
4640 Provides: mail-transport-agent
4641 Conflicts: mail-transport-agent
4642 Replaces: mail-transport-agent
4644 ensuring that only one MTA can be installed at any one
4649 <sect id="sourcebinarydeps">
4650 <heading>Relationships between source and binary packages -
4651 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4652 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4656 Source packages that require certain binary packages to be
4657 installed or absent at the time of building the package
4658 can declare relationships to those binary packages.
4662 This is done using the <tt>Build-Depends</tt>,
4663 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4664 <tt>Build-Conflicts-Indep</tt> control file fields.
4668 Build-dependencies on "build-essential" binary packages can be
4669 omitted. Please see <ref id="pkg-relations"> for more information.
4673 The dependencies and conflicts they define must be satisfied
4674 (as defined earlier for binary packages) in order to invoke
4675 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4677 If you make "build-arch" or "binary-arch", you need
4678 Build-Depends. If you make "build-indep" or
4679 "binary-indep", you need Build-Depends and
4680 Build-Depends-Indep. If you make "build" or "binary",
4684 There is no Build-Depends-Arch; this role is essentially
4685 met with Build-Depends. Anyone building the
4686 <tt>build-indep</tt> and binary-indep<tt></tt> targets
4687 is basically assumed to be building the whole package
4688 anyway and so installs all build dependencies. The
4689 autobuilders use <tt>dpkg-buildpackage -B</tt>, which
4690 calls <tt>build</tt> (not <tt>build-arch</tt>, since it
4691 does not yet know how to check for its existence) and
4692 <tt>binary-arch</tt>.
4695 The purpose of the original split, I recall, was so that
4696 the autobuilders wouldn't need to install extra packages
4697 needed only for the binary-indep targets. But without a
4698 build-arch/build-indep split, this didn't work, since
4699 most of the work is done in the build target, not in the
4705 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4707 The <tt>Build-Depends</tt> and
4708 <tt>Build-Conflicts</tt> fields must be satisfied when
4709 any of the following targets is invoked:
4710 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4711 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4712 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4714 <tag><tt>Build-Depends-Indep</tt>,
4715 <tt>Build-Conflicts-Indep</tt></tag>
4717 The <tt>Build-Depends-Indep</tt> and
4718 <tt>Build-Conflicts-Indep</tt> fields must be
4719 satisfied when any of the following targets is
4720 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4721 <tt>binary</tt> and <tt>binary-indep</tt>.
4731 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4734 Packages containing shared libraries must be constructed with
4735 a little care to make sure that the shared library is always
4736 available. This is especially important for packages whose
4737 shared libraries are vitally important, such as the C library
4738 (currently <tt>libc6</tt>).
4742 Packages involving shared libraries should be split up into
4743 several binary packages. This section mostly deals with how
4744 this separation is to be accomplished; rules for files within
4745 the shared library packages are in <ref id="libraries"> instead.
4748 <sect id="sharedlibs-runtime">
4749 <heading>Run-time shared libraries</heading>
4752 The run-time shared library needs to be placed in a package
4753 whose name changes whenever the shared object version
4756 Since it is common place to install several versions of a
4757 package that just provides shared libraries, it is a
4758 good idea that the library package should not
4759 contain any extraneous non-versioned files, unless they
4760 happen to be in versioned directories.</p>
4762 The most common mechanism is to place it in a package
4764 <package><var>libraryname</var><var>soversion</var></package>,
4765 where <file><var>soversion</var></file> is the version number
4766 in the soname of the shared library<footnote>
4767 The soname is the shared object name: it's the thing
4768 that has to match exactly between building an executable
4769 and running it for the dynamic linker to be able run the
4770 program. For example, if the soname of the library is
4771 <file>libfoo.so.6</file>, the library package would be
4772 called <file>libfoo6</file>.
4774 Alternatively, if it would be confusing to directly append
4775 <var>soversion</var> to <var>libraryname</var> (e.g. because
4776 <var>libraryname</var> itself ends in a number), you may use
4777 <package><var>libraryname</var>-<var>soversion</var></package> and
4778 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4783 If you have several shared libraries built from the same
4784 source tree you may lump them all together into a single
4785 shared library package, provided that you change all of
4786 their sonames at once (so that you don't get filename
4787 clashes if you try to install different versions of the
4788 combined shared libraries package).
4792 The package should install the shared libraries under
4793 their normal names. For example, the <package>libgdbm3</package>
4794 package should install <file>libgdbm.so.3.0.0</file> as
4795 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4796 renamed or re-linked by any <prgn>prerm</prgn> or
4797 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4798 of renaming things safely without affecting running programs,
4799 and attempts to interfere with this are likely to lead to
4804 Shared libraries should not be installed executable, since
4805 the dynamic linker does not require this and trying to
4806 execute a shared library usually results in a core dump.
4810 The run-time library package should include the symbolic link that
4811 <prgn>ldconfig</prgn> would create for the shared libraries.
4812 For example, the <package>libgdbm3</package> package should include
4813 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4814 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4815 linker (for example <prgn>ld.so</prgn> or
4816 <prgn>ld-linux.so.*</prgn>) can find the library between the
4817 time that <prgn>dpkg</prgn> installs it and the time that
4818 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4820 The package management system requires the library to be
4821 placed before the symbolic link pointing to it in the
4822 <file>.deb</file> file. This is so that when
4823 <prgn>dpkg</prgn> comes to install the symlink
4824 (overwriting the previous symlink pointing at an older
4825 version of the library), the new shared library is already
4826 in place. In the past, this was achieved by creating the
4827 library in the temporary packaging directory before
4828 creating the symlink. Unfortunately, this was not always
4829 effective, since the building of the tar file in the
4830 <file>.deb</file> depended on the behavior of the underlying
4831 file system. Some file systems (such as reiserfs) reorder
4832 the files so that the order of creation is forgotten.
4833 Since version 1.7.0, <prgn>dpkg</prgn>
4834 reorders the files itself as necessary when building a
4835 package. Thus it is no longer important to concern
4836 oneself with the order of file creation.
4840 <sect1 id="ldconfig">
4841 <heading><tt>ldconfig</tt></heading>
4844 Any package installing shared libraries in one of the default
4845 library directories of the dynamic linker (which are currently
4846 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4847 listed in <file>/etc/ld.so.conf</file><footnote>
4849 <list compact="compact">
4850 <item>/usr/local/lib</item>
4851 <item>/usr/lib/libc5-compat</item>
4852 <item>/lib/libc5-compat</item>
4855 must use <prgn>ldconfig</prgn> to update the shared library
4860 The package maintainer scripts must only call
4861 <prgn>ldconfig</prgn> under these circumstances:
4862 <list compact="compact">
4863 <item>When the <prgn>postinst</prgn> script is run with a
4864 first argument of <tt>configure</tt>, the script must call
4865 <prgn>ldconfig</prgn>, and may optionally invoke
4866 <prgn>ldconfig</prgn> at other times.
4868 <item>When the <prgn>postrm</prgn> script is run with a
4869 first argument of <tt>remove</tt>, the script should call
4870 <prgn>ldconfig</prgn>.
4875 During install or upgrade, the preinst is called before
4876 the new files are installed, so calling "ldconfig" is
4877 pointless. The preinst of an existing package can also be
4878 called if an upgrade fails. However, this happens during
4879 the critical time when a shared libs may exist on-disk
4880 under a temporary name. Thus, it is dangerous and
4881 forbidden by current policy to call "ldconfig" at this
4886 When a package is installed or upgraded, "postinst
4887 configure" runs after the new files are safely on-disk.
4888 Since it is perfectly safe to invoke ldconfig
4889 unconditionally in a postinst, it is OK for a package to
4890 simply put ldconfig in its postinst without checking the
4891 argument. The postinst can also be called to recover from
4892 a failed upgrade. This happens before any new files are
4893 unpacked, so there is no reason to call "ldconfig" at this
4898 For a package that is being removed, prerm is
4899 called with all the files intact, so calling ldconfig is
4900 useless. The other calls to "prerm" happen in the case of
4901 upgrade at a time when all the files of the old package
4902 are on-disk, so again calling "ldconfig" is pointless.
4906 postrm, on the other hand, is called with the "remove"
4907 argument just after the files are removed, so this is
4908 the proper time to call "ldconfig" to notify the system
4909 of the fact that the shared libraries from the package
4910 are removed. The postrm can be called at several other
4911 times. At the time of "postrm purge", "postrm
4912 abort-install", or "postrm abort-upgrade", calling
4913 "ldconfig" is useless because the shared lib files are
4914 not on-disk. However, when "postrm" is invoked with
4915 arguments "upgrade", "failed-upgrade", or "disappear", a
4916 shared lib may exist on-disk under a temporary filename.
4924 <sect id="sharedlibs-support-files">
4925 <heading>Shared library support files</heading>
4928 If your package contains files whose names do not change with
4929 each change in the library shared object version, you must not
4930 put them in the shared library package. Otherwise, several
4931 versions of the shared library cannot be installed at the same
4932 time without filename clashes, making upgrades and transitions
4933 unnecessarily difficult.
4937 It is recommended that supporting files and run-time support
4938 programs that do not need to be invoked manually by users, but
4939 are nevertheless required for the package to function, be placed
4940 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
4941 preferably under <file>/usr/lib/</file><var>package-name</var>.
4942 If the program or file is architecture independent, the
4943 recommendation is for it to be placed in a subdirectory of
4944 <file>/usr/share</file> instead, preferably under
4945 <file>/usr/share/</file><var>package-name</var>. Following the
4946 <var>package-name</var> naming convention ensures that the file
4947 names change when the shared object version changes.
4951 Run-time support programs that use the shared library but are
4952 not required for the library to function or files used by the
4953 shared library that can be used by any version of the shared
4954 library package should instead be put in a separate package.
4955 This package might typically be named
4956 <package><var>libraryname</var>-tools</package>; note the
4957 absence of the <var>soversion</var> in the package name.
4961 Files and support programs only useful when compiling software
4962 against the library should be included in the development
4963 package for the library.<footnote>
4964 For example, a <file><var>package-name</var>-config</file>
4965 script or <package>pkg-config</package> configuration files.
4970 <sect id="sharedlibs-static">
4971 <heading>Static libraries</heading>
4974 The static library (<file><var>libraryname.a</var></file>)
4975 is usually provided in addition to the shared version.
4976 It is placed into the development package (see below).
4980 In some cases, it is acceptable for a library to be
4981 available in static form only; these cases include:
4983 <item>libraries for languages whose shared library support
4984 is immature or unstable</item>
4985 <item>libraries whose interfaces are in flux or under
4986 development (commonly the case when the library's
4987 major version number is zero, or where the ABI breaks
4988 across patchlevels)</item>
4989 <item>libraries which are explicitly intended to be
4990 available only in static form by their upstream
4995 <sect id="sharedlibs-dev">
4996 <heading>Development files</heading>
4999 The development files associated to a shared library need to be
5000 placed in a package called
5001 <package><var>libraryname</var><var>soversion</var>-dev</package>,
5002 or if you prefer only to support one development version at a
5003 time, <package><var>libraryname</var>-dev</package>.
5007 In case several development versions of a library exist, you may
5008 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5009 <ref id="conflicts">) to ensure that the user only installs one
5010 development version at a time (as different development versions are
5011 likely to have the same header files in them, which would cause a
5012 filename clash if both were installed).
5016 The development package should contain a symlink for the associated
5017 shared library without a version number. For example, the
5018 <package>libgdbm-dev</package> package should include a symlink
5019 from <file>/usr/lib/libgdbm.so</file> to
5020 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5021 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5022 <file>libgdbm.so</file> when compiling dynamically.
5026 <sect id="sharedlibs-intradeps">
5027 <heading>Dependencies between the packages of the same library</heading>
5030 Typically the development version should have an exact
5031 version dependency on the runtime library, to make sure that
5032 compilation and linking happens correctly. The
5033 <tt>${binary:Version}</tt> substitution variable can be
5034 useful for this purpose.
5036 Previously, <tt>${Source-Version}</tt> was used, but its name
5037 was confusing and it has been deprecated since dpkg 1.13.19.
5042 <sect id="sharedlibs-shlibdeps">
5043 <heading>Dependencies between the library and other packages -
5044 the <tt>shlibs</tt> system</heading>
5047 If a package contains a binary or library which links to a
5048 shared library, we must ensure that when the package is
5049 installed on the system, all of the libraries needed are
5050 also installed. This requirement led to the creation of the
5051 <tt>shlibs</tt> system, which is very simple in its design:
5052 any package which <em>provides</em> a shared library also
5053 provides information on the package dependencies required to
5054 ensure the presence of this library, and any package which
5055 <em>uses</em> a shared library uses this information to
5056 determine the dependencies it requires. The files which
5057 contain the mapping from shared libraries to the necessary
5058 dependency information are called <file>shlibs</file> files.
5062 Thus, when a package is built which contains any shared
5063 libraries, it must provide a <file>shlibs</file> file for other
5064 packages to use, and when a package is built which contains
5065 any shared libraries or compiled binaries, it must run
5066 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5067 on these to determine the libraries used and hence the
5068 dependencies needed by this package.<footnote>
5070 In the past, the shared libraries linked to were
5071 determined by calling <prgn>ldd</prgn>, but now
5072 <prgn>objdump</prgn> is used to do this. The only
5073 change this makes to package building is that
5074 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
5075 libraries, whereas in the past this was unnecessary.
5076 The rest of this footnote explains the advantage that
5081 We say that a binary <tt>foo</tt> <em>directly</em> uses
5082 a library <tt>libbar</tt> if it is explicitly linked
5083 with that library (that is, it uses the flag
5084 <tt>-lbar</tt> during the linking stage). Other
5085 libraries that are needed by <tt>libbar</tt> are linked
5086 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5087 linker will load them automatically when it loads
5088 <tt>libbar</tt>. A package should depend on
5089 the libraries it directly uses, and the dependencies for
5090 those libraries should automatically pull in the other
5095 Unfortunately, the <prgn>ldd</prgn> program shows both
5096 the directly and indirectly used libraries, meaning that
5097 the dependencies determined included both direct and
5098 indirect dependencies. The use of <prgn>objdump</prgn>
5099 avoids this problem by determining only the directly
5104 A good example of where this helps is the following. We
5105 could update <tt>libimlib</tt> with a new version that
5106 supports a new graphics format called dgf (but retaining
5107 the same major version number). If we used the old
5108 <prgn>ldd</prgn> method, every package that uses
5109 <tt>libimlib</tt> would need to be recompiled so it
5110 would also depend on <tt>libdgf</tt> or it wouldn't run
5111 due to missing symbols. However with the new system,
5112 packages using <tt>libimlib</tt> can rely on
5113 <tt>libimlib</tt> itself having the dependency on
5114 <tt>libdgf</tt> and so they would not need rebuilding.
5120 In the following sections, we will first describe where the
5121 various <tt>shlibs</tt> files are to be found, then how to
5122 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5123 file format and how to create them if your package contains a
5128 <heading>The <tt>shlibs</tt> files present on the system</heading>
5131 There are several places where <tt>shlibs</tt> files are
5132 found. The following list gives them in the order in which
5134 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5135 (The first one which gives the required information is used.)
5141 <p><file>debian/shlibs.local</file></p>
5144 This lists overrides for this package. Its use is
5145 described below (see <ref id="shlibslocal">).
5150 <p><file>/etc/dpkg/shlibs.override</file></p>
5153 This lists global overrides. This list is normally
5154 empty. It is maintained by the local system
5160 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5163 When packages are being built, any
5164 <file>debian/shlibs</file> files are copied into the
5165 control file area of the temporary build directory and
5166 given the name <file>shlibs</file>. These files give
5167 details of any shared libraries included in the
5169 An example may help here. Let us say that the
5170 source package <tt>foo</tt> generates two binary
5171 packages, <tt>libfoo2</tt> and
5172 <tt>foo-runtime</tt>. When building the binary
5173 packages, the two packages are created in the
5174 directories <file>debian/libfoo2</file> and
5175 <file>debian/foo-runtime</file> respectively.
5176 (<file>debian/tmp</file> could be used instead of one
5177 of these.) Since <tt>libfoo2</tt> provides the
5178 <tt>libfoo</tt> shared library, it will require a
5179 <tt>shlibs</tt> file, which will be installed in
5180 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
5182 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
5183 when <prgn>dpkg-shlibdeps</prgn> is run on the
5185 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
5187 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5188 determine whether <tt>foo-prog</tt>'s library
5189 dependencies are satisfied by any of the libraries
5190 provided by <tt>libfoo2</tt>. For this reason,
5191 <prgn>dpkg-shlibdeps</prgn> must only be run once
5192 all of the individual binary packages'
5193 <tt>shlibs</tt> files have been installed into the
5200 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5203 These are the <file>shlibs</file> files corresponding to
5204 all of the packages installed on the system, and are
5205 maintained by the relevant package maintainers.
5210 <p><file>/etc/dpkg/shlibs.default</file></p>
5213 This file lists any shared libraries whose packages
5214 have failed to provide correct <file>shlibs</file> files.
5215 It was used when the <file>shlibs</file> setup was first
5216 introduced, but it is now normally empty. It is
5217 maintained by the <tt>dpkg</tt> maintainer.
5225 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5226 <file>shlibs</file> files</heading>
5230 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5231 into your <file>debian/rules</file> file. If your package
5232 contains only compiled binaries and libraries (but no scripts),
5233 you can use a command such as:
5234 <example compact="compact">
5235 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5236 debian/tmp/usr/lib/*
5238 Otherwise, you will need to explicitly list the compiled
5239 binaries and libraries.<footnote>
5240 If you are using <tt>debhelper</tt>, the
5241 <prgn>dh_shlibdeps</prgn> program will do this work for
5242 you. It will also correctly handle multi-binary
5248 This command puts the dependency information into the
5249 <file>debian/substvars</file> file, which is then used by
5250 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5251 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5252 field in the control file for this to work.
5256 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
5257 done. If it does complain you might need to create your own
5258 <file>debian/shlibs.local</file> file, as explained below (see
5259 <ref id="shlibslocal">).
5263 If you have multiple binary packages, you will need to call
5264 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5265 compiled libraries or binaries. In such a case, you will
5266 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5267 utilities to specify a different <file>substvars</file> file.
5271 If you are creating a udeb for use in the Debian Installer, you
5272 will need to specify that <prgn>dpkg-shlibdeps</prgn> should use
5273 the dependency line of type <tt>udeb</tt> by adding
5274 <tt>-tudeb</tt> as option<footnote>
5275 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5276 will automatically add this option if it knows it is
5278 </footnote>. If there is no dependency line of type <tt>udeb</tt>
5279 in the <file>shlibs</file> file, <prgn>dpkg-shlibdeps</prgn> will
5280 fall back to the regular dependency line.
5284 For more details on dpkg-shlibdeps, please see
5285 <ref id="pkg-dpkg-shlibdeps"> and
5286 <manref name="dpkg-shlibdeps" section="1">.
5291 <heading>The <file>shlibs</file> File Format</heading>
5294 Each <file>shlibs</file> file has the same format. Lines
5295 beginning with <tt>#</tt> are considered to be comments and
5296 are ignored. Each line is of the form:
5297 <example compact="compact">
5298 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5303 We will explain this by reference to the example of the
5304 <tt>zlib1g</tt> package, which (at the time of writing)
5305 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5309 <var>type</var> is an optional element that indicates the type
5310 of package for which the line is valid. The only type currently
5311 in use is <tt>udeb</tt>. The colon and space after the type are
5316 <var>library-name</var> is the name of the shared library,
5317 in this case <tt>libz</tt>. (This must match the name part
5318 of the soname, see below.)
5322 <var>soname-version</var> is the version part of the soname of
5323 the library. The soname is the thing that must exactly match
5324 for the library to be recognized by the dynamic linker, and is
5326 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5327 example, <tt>libz.so.1</tt>.<footnote>
5328 This can be determined using the command
5329 <example compact="compact">
5330 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5333 The version part is the part which comes after
5334 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
5338 <var>dependencies</var> has the same syntax as a dependency
5339 field in a binary package control file. It should give
5340 details of which packages are required to satisfy a binary
5341 built against the version of the library contained in the
5342 package. See <ref id="depsyntax"> for details.
5346 In our example, if the first version of the <tt>zlib1g</tt>
5347 package which contained a minor number of at least
5348 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5349 <tt>shlibs</tt> entry for this library could say:
5350 <example compact="compact">
5351 libz 1 zlib1g (>= 1:1.1.3)
5353 The version-specific dependency is to avoid warnings from
5354 the dynamic linker about using older shared libraries with
5359 As zlib1g also provides a udeb containing the shared library,
5360 there would also be a second line:
5361 <example compact="compact">
5362 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5368 <heading>Providing a <file>shlibs</file> file</heading>
5371 If your package provides a shared library, you need to create
5372 a <file>shlibs</file> file following the format described above.
5373 It is usual to call this file <file>debian/shlibs</file> (but if
5374 you have multiple binary packages, you might want to call it
5375 <file>debian/shlibs.<var>package</var></file> instead). Then
5376 let <file>debian/rules</file> install it in the control area:
5377 <example compact="compact">
5378 install -m644 debian/shlibs debian/tmp/DEBIAN
5380 or, in the case of a multi-binary package:
5381 <example compact="compact">
5382 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5384 An alternative way of doing this is to create the
5385 <file>shlibs</file> file in the control area directly from
5386 <file>debian/rules</file> without using a <file>debian/shlibs</file>
5387 file at all,<footnote>
5388 This is what <prgn>dh_makeshlibs</prgn> in the
5389 <tt>debhelper</tt> suite does. If your package also has a udeb
5390 that provides a shared library, <prgn>dh_makeshlibs</prgn> can
5391 automatically generate the <tt>udeb:</tt> lines if you specify
5392 the name of the udeb with the <tt>--add-udeb</tt> option.
5394 since the <file>debian/shlibs</file> file itself is ignored by
5395 <prgn>dpkg-shlibdeps</prgn>.
5399 As <prgn>dpkg-shlibdeps</prgn> reads the
5400 <file>DEBIAN/shlibs</file> files in all of the binary packages
5401 being built from this source package, all of the
5402 <file>DEBIAN/shlibs</file> files should be installed before
5403 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5408 <sect1 id="shlibslocal">
5409 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
5412 This file is intended only as a <em>temporary</em> fix if
5413 your binaries or libraries depend on a library whose package
5414 does not yet provide a correct <file>shlibs</file> file.
5418 We will assume that you are trying to package a binary
5419 <tt>foo</tt>. When you try running
5420 <prgn>dpkg-shlibdeps</prgn> you get the following error
5421 message (<tt>-O</tt> displays the dependency information on
5422 <tt>stdout</tt> instead of writing it to
5423 <tt>debian/substvars</tt>, and the lines have been wrapped
5424 for ease of reading):
5425 <example compact="compact">
5426 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
5427 dpkg-shlibdeps: warning: unable to find dependency
5428 information for shared library libbar (soname 1,
5429 path /usr/lib/libbar.so.1, dependency field Depends)
5430 shlibs:Depends=libc6 (>= 2.2.2-2)
5432 You can then run <prgn>ldd</prgn> on the binary to find the
5433 full location of the library concerned:
5434 <example compact="compact">
5436 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5437 libc.so.6 => /lib/libc.so.6 (0x40032000)
5438 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5440 So the <prgn>foo</prgn> binary depends on the
5441 <prgn>libbar</prgn> shared library, but no package seems to
5442 provide a <file>*.shlibs</file> file handling
5443 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5444 determine the package responsible:
5445 <example compact="compact">
5446 $ dpkg -S /usr/lib/libbar.so.1
5447 bar1: /usr/lib/libbar.so.1
5448 $ dpkg -s bar1 | grep Version
5451 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5452 is the one we are using. Now we can file a bug against the
5453 <tt>bar1</tt> package and create our own
5454 <file>debian/shlibs.local</file> to locally fix the problem.
5455 Including the following line into your
5456 <file>debian/shlibs.local</file> file:
5457 <example compact="compact">
5458 libbar 1 bar1 (>= 1.0-1)
5460 should allow the package build to work.
5464 As soon as the maintainer of <tt>bar1</tt> provides a
5465 correct <file>shlibs</file> file, you should remove this line
5466 from your <file>debian/shlibs.local</file> file. (You should
5467 probably also then have a versioned <tt>Build-Depends</tt>
5468 on <tt>bar1</tt> to help ensure that others do not have the
5469 same problem building your package.)
5478 <chapt id="opersys"><heading>The Operating System</heading>
5481 <heading>File system hierarchy</heading>
5485 <heading>File system Structure</heading>
5488 The location of all installed files and directories must
5489 comply with the File system Hierarchy Standard (FHS),
5490 version 2.3, with the exceptions noted below, and except
5491 where doing so would violate other terms of Debian
5492 Policy. The following exceptions to the FHS apply:
5497 Legacy XFree86 servers are permitted to retain the
5498 configuration file location
5499 <file>/etc/X11/XF86Config-4</file>.
5504 The optional rules related to user specific
5505 configuration files for applications are stored in
5506 the user's home directory are relaxed. It is
5507 recommended that such files start with the
5508 '<tt>.</tt>' character (a "dot file"), and if an
5509 application needs to create more than one dot file
5510 then the preferred placement is in a subdirectory
5511 with a name starting with a '.' character, (a "dot
5512 directory"). In this case it is recommended the
5513 configuration files not start with the '.'
5519 The requirement for amd64 to use <file>/lib64</file>
5520 for 64 bit binaries is removed.
5525 The requirement that
5526 <file>/usr/local/share/man</file> be "synonymous"
5527 with <file>/usr/local/man</file> is relaxed to a
5532 The requirement that windowmanagers with a single
5533 configuration file call it <file>system.*wmrc</file>
5534 is removed, as is the restriction that the window
5535 manager subdirectory be named identically to the
5536 window manager name itself.
5541 The requirement that boot manager configuration
5542 files live in <file>/etc</file>, or at least are
5543 symlinked there, is relaxed to a recommendation.
5550 The version of this document referred here can be
5551 found in the <tt>debian-policy</tt> package or on <url
5552 id="http://www.debian.org/doc/packaging-manuals/fhs/"
5553 name="FHS (Debian copy)"> alongside this manual (or, if
5554 you have the <package>debian-policy</package> installed,
5556 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5557 (local copy)">). The
5558 latest version, which may be a more recent version, may
5560 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5561 Specific questions about following the standard may be
5562 asked on the <tt>debian-devel</tt> mailing list, or
5563 referred to the FHS mailing list (see the
5564 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5570 <heading>Site-specific programs</heading>
5573 As mandated by the FHS, packages must not place any
5574 files in <file>/usr/local</file>, either by putting them in
5575 the file system archive to be unpacked by <prgn>dpkg</prgn>
5576 or by manipulating them in their maintainer scripts.
5580 However, the package may create empty directories below
5581 <file>/usr/local</file> so that the system administrator knows
5582 where to place site-specific files. These are not
5583 directories <em>in</em> <file>/usr/local</file>, but are
5584 children of directories in <file>/usr/local</file>. These
5585 directories (<file>/usr/local/*/dir/</file>)
5586 should be removed on package removal if they are
5591 Note, that this applies only to directories <em>below</em>
5592 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
5593 Packages must not create sub-directories in the directory
5594 <file>/usr/local</file> itself, except those listed in FHS,
5595 section 4.5. However, you may create directories below
5596 them as you wish. You must not remove any of the
5597 directories listed in 4.5, even if you created them.
5601 Since <file>/usr/local</file> can be mounted read-only from a
5602 remote server, these directories must be created and
5603 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5604 maintainer scripts and not be included in the
5605 <file>.deb</file> archive. These scripts must not fail if
5606 either of these operations fail.
5610 For example, the <tt>emacsen-common</tt> package could
5611 contain something like
5612 <example compact="compact">
5613 if [ ! -e /usr/local/share/emacs ]
5615 if mkdir /usr/local/share/emacs 2>/dev/null
5617 chown root:staff /usr/local/share/emacs
5618 chmod 2775 /usr/local/share/emacs
5622 in its <prgn>postinst</prgn> script, and
5623 <example compact="compact">
5624 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5625 rmdir /usr/local/share/emacs 2>/dev/null || true
5627 in the <prgn>prerm</prgn> script. (Note that this form is
5628 used to ensure that if the script is interrupted, the
5629 directory <file>/usr/local/share/emacs</file> will still be
5634 If you do create a directory in <file>/usr/local</file> for
5635 local additions to a package, you should ensure that
5636 settings in <file>/usr/local</file> take precedence over the
5637 equivalents in <file>/usr</file>.
5641 However, because <file>/usr/local</file> and its contents are
5642 for exclusive use of the local administrator, a package
5643 must not rely on the presence or absence of files or
5644 directories in <file>/usr/local</file> for normal operation.
5648 The <file>/usr/local</file> directory itself and all the
5649 subdirectories created by the package should (by default) have
5650 permissions 2775 (group-writable and set-group-id) and be
5651 owned by <tt>root:staff</tt>.
5656 <heading>The system-wide mail directory</heading>
5658 The system-wide mail directory is <file>/var/mail</file>. This
5659 directory is part of the base system and should not owned
5660 by any particular mail agents. The use of the old
5661 location <file>/var/spool/mail</file> is deprecated, even
5662 though the spool may still be physically located there.
5663 To maintain partial upgrade compatibility for systems
5664 which have <file>/var/spool/mail</file> as their physical mail
5665 spool, packages using <file>/var/mail</file> must depend on
5666 either <package>libc6</package> (>= 2.1.3-13), or on
5667 <package>base-files</package> (>= 2.2.0), or on later
5668 versions of either one of these packages.
5674 <heading>Users and groups</heading>
5677 <heading>Introduction</heading>
5679 The Debian system can be configured to use either plain or
5684 Some user ids (UIDs) and group ids (GIDs) are reserved
5685 globally for use by certain packages. Because some
5686 packages need to include files which are owned by these
5687 users or groups, or need the ids compiled into binaries,
5688 these ids must be used on any Debian system only for the
5689 purpose for which they are allocated. This is a serious
5690 restriction, and we should avoid getting in the way of
5691 local administration policies. In particular, many sites
5692 allocate users and/or local system groups starting at 100.
5696 Apart from this we should have dynamically allocated ids,
5697 which should by default be arranged in some sensible
5698 order, but the behavior should be configurable.
5702 Packages other than <tt>base-passwd</tt> must not modify
5703 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5704 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5709 <heading>UID and GID classes</heading>
5711 The UID and GID numbers are divided into classes as
5717 Globally allocated by the Debian project, the same
5718 on every Debian system. These ids will appear in
5719 the <file>passwd</file> and <file>group</file> files of all
5720 Debian systems, new ids in this range being added
5721 automatically as the <tt>base-passwd</tt> package is
5726 Packages which need a single statically allocated
5727 uid or gid should use one of these; their
5728 maintainers should ask the <tt>base-passwd</tt>
5736 Dynamically allocated system users and groups.
5737 Packages which need a user or group, but can have
5738 this user or group allocated dynamically and
5739 differently on each system, should use <tt>adduser
5740 --system</tt> to create the group and/or user.
5741 <prgn>adduser</prgn> will check for the existence of
5742 the user or group, and if necessary choose an unused
5743 id based on the ranges specified in
5744 <file>adduser.conf</file>.
5748 <tag>1000-29999:</tag>
5751 Dynamically allocated user accounts. By default
5752 <prgn>adduser</prgn> will choose UIDs and GIDs for
5753 user accounts in this range, though
5754 <file>adduser.conf</file> may be used to modify this
5759 <tag>30000-59999:</tag>
5764 <tag>60000-64999:</tag>
5767 Globally allocated by the Debian project, but only
5768 created on demand. The ids are allocated centrally
5769 and statically, but the actual accounts are only
5770 created on users' systems on demand.
5774 These ids are for packages which are obscure or
5775 which require many statically-allocated ids. These
5776 packages should check for and create the accounts in
5777 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5778 <prgn>adduser</prgn> if it has this facility) if
5779 necessary. Packages which are likely to require
5780 further allocations should have a "hole" left after
5781 them in the allocation, to give them room to
5786 <tag>65000-65533:</tag>
5794 User <tt>nobody</tt>. The corresponding gid refers
5795 to the group <tt>nogroup</tt>.
5802 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5803 not</em> be used, because it is the error return
5812 <sect id="sysvinit">
5813 <heading>System run levels and <file>init.d</file> scripts</heading>
5815 <sect1 id="/etc/init.d">
5816 <heading>Introduction</heading>
5819 The <file>/etc/init.d</file> directory contains the scripts
5820 executed by <prgn>init</prgn> at boot time and when the
5821 init state (or "runlevel") is changed (see <manref
5822 name="init" section="8">).
5826 There are at least two different, yet functionally
5827 equivalent, ways of handling these scripts. For the sake
5828 of simplicity, this document describes only the symbolic
5829 link method. However, it must not be assumed by maintainer
5830 scripts that this method is being used, and any automated
5831 manipulation of the various runlevel behaviors by
5832 maintainer scripts must be performed using
5833 <prgn>update-rc.d</prgn> as described below and not by
5834 manually installing or removing symlinks. For information
5835 on the implementation details of the other method,
5836 implemented in the <tt>file-rc</tt> package, please refer
5837 to the documentation of that package.
5841 These scripts are referenced by symbolic links in the
5842 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5843 runlevels, <prgn>init</prgn> looks in the directory
5844 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5845 execute, where <tt><var>n</var></tt> is the runlevel that
5846 is being changed to, or <tt>S</tt> for the boot-up
5851 The names of the links all have the form
5852 <file>S<var>mm</var><var>script</var></file> or
5853 <file>K<var>mm</var><var>script</var></file> where
5854 <var>mm</var> is a two-digit number and <var>script</var>
5855 is the name of the script (this should be the same as the
5856 name of the actual script in <file>/etc/init.d</file>).
5860 When <prgn>init</prgn> changes runlevel first the targets
5861 of the links whose names start with a <tt>K</tt> are
5862 executed, each with the single argument <tt>stop</tt>,
5863 followed by the scripts prefixed with an <tt>S</tt>, each
5864 with the single argument <tt>start</tt>. (The links are
5865 those in the <file>/etc/rc<var>n</var>.d</file> directory
5866 corresponding to the new runlevel.) The <tt>K</tt> links
5867 are responsible for killing services and the <tt>S</tt>
5868 link for starting services upon entering the runlevel.
5872 For example, if we are changing from runlevel 2 to
5873 runlevel 3, init will first execute all of the <tt>K</tt>
5874 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
5875 all of the <tt>S</tt> prefixed scripts in that directory.
5876 The links starting with <tt>K</tt> will cause the
5877 referred-to file to be executed with an argument of
5878 <tt>stop</tt>, and the <tt>S</tt> links with an argument
5883 The two-digit number <var>mm</var> is used to determine
5884 the order in which to run the scripts: low-numbered links
5885 have their scripts run first. For example, the
5886 <tt>K20</tt> scripts will be executed before the
5887 <tt>K30</tt> scripts. This is used when a certain service
5888 must be started before another. For example, the name
5889 server <prgn>bind</prgn> might need to be started before
5890 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
5891 can set up its access lists. In this case, the script
5892 that starts <prgn>bind</prgn> would have a lower number
5893 than the script that starts <prgn>inn</prgn> so that it
5895 <example compact="compact">
5902 The two runlevels 0 (halt) and 6 (reboot) are slightly
5903 different. In these runlevels, the links with an
5904 <tt>S</tt> prefix are still called after those with a
5905 <tt>K</tt> prefix, but they too are called with the single
5906 argument <tt>stop</tt>.
5910 Also, if the script name ends in <tt>.sh</tt>, the script
5911 will be sourced in runlevel <tt>S</tt> rather than being
5912 run in a forked subprocess, but will be explicitly run by
5913 <prgn>sh</prgn> in all other runlevels.
5918 <heading>Writing the scripts</heading>
5921 Packages that include daemons for system services should
5922 place scripts in <file>/etc/init.d</file> to start or stop
5923 services at boot time or during a change of runlevel.
5924 These scripts should be named
5925 <file>/etc/init.d/<var>package</var></file>, and they should
5926 accept one argument, saying what to do:
5929 <tag><tt>start</tt></tag>
5930 <item>start the service,</item>
5932 <tag><tt>stop</tt></tag>
5933 <item>stop the service,</item>
5935 <tag><tt>restart</tt></tag>
5936 <item>stop and restart the service if it's already running,
5937 otherwise start the service</item>
5939 <tag><tt>reload</tt></tag>
5940 <item><p>cause the configuration of the service to be
5941 reloaded without actually stopping and restarting
5944 <tag><tt>force-reload</tt></tag>
5945 <item>cause the configuration to be reloaded if the
5946 service supports this, otherwise restart the
5950 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
5951 <tt>force-reload</tt> options should be supported by all
5952 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
5957 The <file>init.d</file> scripts must ensure that they will
5958 behave sensibly (i.e., returning success and not starting
5959 multiple copies of a service) if invoked with <tt>start</tt>
5960 when the service is already running, or with <tt>stop</tt>
5961 when it isn't, and that they don't kill unfortunately-named
5962 user processes. The best way to achieve this is usually to
5963 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
5968 If a service reloads its configuration automatically (as
5969 in the case of <prgn>cron</prgn>, for example), the
5970 <tt>reload</tt> option of the <file>init.d</file> script
5971 should behave as if the configuration has been reloaded
5976 The <file>/etc/init.d</file> scripts must be treated as
5977 configuration files, either (if they are present in the
5978 package, that is, in the .deb file) by marking them as
5979 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
5980 by managing them correctly in the maintainer scripts (see
5981 <ref id="config-files">). This is important since we want
5982 to give the local system administrator the chance to adapt
5983 the scripts to the local system, e.g., to disable a
5984 service without de-installing the package, or to specify
5985 some special command line options when starting a service,
5986 while making sure their changes aren't lost during the next
5991 These scripts should not fail obscurely when the
5992 configuration files remain but the package has been
5993 removed, as configuration files remain on the system after
5994 the package has been removed. Only when <prgn>dpkg</prgn>
5995 is executed with the <tt>--purge</tt> option will
5996 configuration files be removed. In particular, as the
5997 <file>/etc/init.d/<var>package</var></file> script itself is
5998 usually a <tt>conffile</tt>, it will remain on the system
5999 if the package is removed but not purged. Therefore, you
6000 should include a <tt>test</tt> statement at the top of the
6002 <example compact="compact">
6003 test -f <var>program-executed-later-in-script</var> || exit 0
6008 Often there are some variables in the <file>init.d</file>
6009 scripts whose values control the behavior of the scripts,
6010 and which a system administrator is likely to want to
6011 change. As the scripts themselves are frequently
6012 <tt>conffile</tt>s, modifying them requires that the
6013 administrator merge in their changes each time the package
6014 is upgraded and the <tt>conffile</tt> changes. To ease
6015 the burden on the system administrator, such configurable
6016 values should not be placed directly in the script.
6017 Instead, they should be placed in a file in
6018 <file>/etc/default</file>, which typically will have the same
6019 base name as the <file>init.d</file> script. This extra file
6020 should be sourced by the script when the script runs. It
6021 must contain only variable settings and comments in SUSv3
6022 <prgn>sh</prgn> format. It may either be a
6023 <tt>conffile</tt> or a configuration file maintained by
6024 the package maintainer scripts. See <ref id="config-files">
6029 To ensure that vital configurable values are always
6030 available, the <file>init.d</file> script should set default
6031 values for each of the shell variables it uses, either
6032 before sourcing the <file>/etc/default/</file> file or
6033 afterwards using something like the <tt>:
6034 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6035 script must behave sensibly and not fail if the
6036 <file>/etc/default</file> file is deleted.
6041 <heading>Interfacing with the initscript system</heading>
6044 Maintainers should use the abstraction layer provided by
6045 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6046 programs to deal with initscripts in their packages'
6047 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6048 and <prgn>postrm</prgn>.
6052 Directly managing the /etc/rc?.d links and directly
6053 invoking the <file>/etc/init.d/</file> initscripts should
6054 be done only by packages providing the initscript
6055 subsystem (such as <prgn>sysv-rc</prgn> and
6056 <prgn>file-rc</prgn>).
6060 <heading>Managing the links</heading>
6063 The program <prgn>update-rc.d</prgn> is provided for
6064 package maintainers to arrange for the proper creation and
6065 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6066 or their functional equivalent if another method is being
6067 used. This may be used by maintainers in their packages'
6068 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6072 You must not include any <file>/etc/rc<var>n</var>.d</file>
6073 symbolic links in the actual archive or manually create or
6074 remove the symbolic links in maintainer scripts; you must
6075 use the <prgn>update-rc.d</prgn> program instead. (The
6076 former will fail if an alternative method of maintaining
6077 runlevel information is being used.) You must not include
6078 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6079 in the archive either. (Only the <tt>sysvinit</tt>
6084 By default <prgn>update-rc.d</prgn> will start services in
6085 each of the multi-user state runlevels (2, 3, 4, and 5)
6086 and stop them in the halt runlevel (0), the single-user
6087 runlevel (1) and the reboot runlevel (6). The system
6088 administrator will have the opportunity to customize
6089 runlevels by simply adding, moving, or removing the
6090 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6091 symbolic links are being used, or by modifying
6092 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6097 To get the default behavior for your package, put in your
6098 <prgn>postinst</prgn> script
6099 <example compact="compact">
6100 update-rc.d <var>package</var> defaults
6102 and in your <prgn>postrm</prgn>
6103 <example compact="compact">
6104 if [ "$1" = purge ]; then
6105 update-rc.d <var>package</var> remove
6107 </example>. Note that if your package changes runlevels
6108 or priority, you may have to remove and recreate the links,
6109 since otherwise the old links may persist. Refer to the
6110 documentation of <prgn>update-rc.d</prgn>.
6114 This will use a default sequence number of 20. If it does
6115 not matter when or in which order the <file>init.d</file>
6116 script is run, use this default. If it does, then you
6117 should talk to the maintainer of the <prgn>sysvinit</prgn>
6118 package or post to <tt>debian-devel</tt>, and they will
6119 help you choose a number.
6123 For more information about using <tt>update-rc.d</tt>,
6124 please consult its man page <manref name="update-rc.d"
6130 <heading>Running initscripts</heading>
6132 The program <prgn>invoke-rc.d</prgn> is provided to make
6133 it easier for package maintainers to properly invoke an
6134 initscript, obeying runlevel and other locally-defined
6135 constraints that might limit a package's right to start,
6136 stop and otherwise manage services. This program may be
6137 used by maintainers in their packages' scripts.
6141 The package maintainer scripts must use
6142 <prgn>invoke-rc.d</prgn> to invoke the
6143 <file>/etc/init.d/*</file> initscripts, instead of
6144 calling them directly.
6148 By default, <prgn>invoke-rc.d</prgn> will pass any
6149 action requests (start, stop, reload, restart...) to the
6150 <file>/etc/init.d</file> script, filtering out requests
6151 to start or restart a service out of its intended
6156 Most packages will simply need to change:
6157 <example compact="compact">/etc/init.d/<package>
6158 <action></example> in their <prgn>postinst</prgn>
6159 and <prgn>prerm</prgn> scripts to:
6160 <example compact="compact">
6161 if which invoke-rc.d >/dev/null 2>&1; then
6162 invoke-rc.d <var>package</var> <action>
6164 /etc/init.d/<var>package</var> <action>
6170 A package should register its initscript services using
6171 <prgn>update-rc.d</prgn> before it tries to invoke them
6172 using <prgn>invoke-rc.d</prgn>. Invocation of
6173 unregistered services may fail.
6177 For more information about using
6178 <prgn>invoke-rc.d</prgn>, please consult its man page
6179 <manref name="invoke-rc.d" section="8">.
6185 <heading>Boot-time initialization</heading>
6188 There used to be another directory, <file>/etc/rc.boot</file>,
6189 which contained scripts which were run once per machine
6190 boot. This has been deprecated in favour of links from
6191 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6192 described in <ref id="/etc/init.d">. Packages must not
6193 place files in <file>/etc/rc.boot</file>.
6198 <heading>Example</heading>
6201 An example on which you can base your
6202 <file>/etc/init.d</file> scripts is found in
6203 <file>/etc/init.d/skeleton</file>.
6210 <heading>Console messages from <file>init.d</file> scripts</heading>
6213 This section describes the formats to be used for messages
6214 written to standard output by the <file>/etc/init.d</file>
6215 scripts. The intent is to improve the consistency of
6216 Debian's startup and shutdown look and feel. For this
6217 reason, please look very carefully at the details. We want
6218 the messages to have the same format in terms of wording,
6219 spaces, punctuation and case of letters.
6223 Here is a list of overall rules that should be used for
6224 messages generated by <file>/etc/init.d</file> scripts.
6230 The message should fit in one line (fewer than 80
6231 characters), start with a capital letter and end with
6232 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6236 If the script is performing some time consuming task in
6237 the background (not merely starting or stopping a
6238 program, for instance), an ellipsis (three dots:
6239 <tt>...</tt>) should be output to the screen, with no
6240 leading or tailing whitespace or line feeds.
6244 The messages should appear as if the computer is telling
6245 the user what it is doing (politely :-), but should not
6246 mention "it" directly. For example, instead of:
6247 <example compact="compact">
6248 I'm starting network daemons: nfsd mountd.
6250 the message should say
6251 <example compact="compact">
6252 Starting network daemons: nfsd mountd.
6259 <tt>init.d</tt> script should use the following standard
6260 message formats for the situations enumerated below.
6266 <p>When daemons are started</p>
6269 If the script starts one or more daemons, the output
6270 should look like this (a single line, no leading
6272 <example compact="compact">
6273 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6275 The <var>description</var> should describe the
6276 subsystem the daemon or set of daemons are part of,
6277 while <var>daemon-1</var> up to <var>daemon-n</var>
6278 denote each daemon's name (typically the file name of
6283 For example, the output of <file>/etc/init.d/lpd</file>
6285 <example compact="compact">
6286 Starting printer spooler: lpd.
6291 This can be achieved by saying
6292 <example compact="compact">
6293 echo -n "Starting printer spooler: lpd"
6294 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6297 in the script. If there are more than one daemon to
6298 start, the output should look like this:
6299 <example compact="compact">
6300 echo -n "Starting remote file system services:"
6301 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6302 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6303 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6306 This makes it possible for the user to see what is
6307 happening and when the final daemon has been started.
6308 Care should be taken in the placement of white spaces:
6309 in the example above the system administrators can
6310 easily comment out a line if they don't want to start
6311 a specific daemon, while the displayed message still
6317 <p>When a system parameter is being set</p>
6320 If you have to set up different system parameters
6321 during the system boot, you should use this format:
6322 <example compact="compact">
6323 Setting <var>parameter</var> to "<var>value</var>".
6328 You can use a statement such as the following to get
6330 <example compact="compact">
6331 echo "Setting DNS domainname to \"$domainname\"."
6336 Note that the same symbol (<tt>"</tt>) is used for the left
6337 and right quotation marks. A grave accent (<tt>`</tt>) is
6338 not a quote character; neither is an apostrophe
6344 <p>When a daemon is stopped or restarted</p>
6347 When you stop or restart a daemon, you should issue a
6348 message identical to the startup message, except that
6349 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6350 or <tt>Restarting</tt> respectively.
6354 For example, stopping the printer daemon will look like
6356 <example compact="compact">
6357 Stopping printer spooler: lpd.
6363 <p>When something is executed</p>
6366 There are several examples where you have to run a
6367 program at system startup or shutdown to perform a
6368 specific task, for example, setting the system's clock
6369 using <prgn>netdate</prgn> or killing all processes
6370 when the system shuts down. Your message should look
6372 <example compact="compact">
6373 Doing something very useful...done.
6375 You should print the <tt>done.</tt> immediately after
6376 the job has been completed, so that the user is
6377 informed why they have to wait. You can get this
6379 <example compact="compact">
6380 echo -n "Doing something very useful..."
6389 <p>When the configuration is reloaded</p>
6392 When a daemon is forced to reload its configuration
6393 files you should use the following format:
6394 <example compact="compact">
6395 Reloading <var>description</var> configuration...done.
6397 where <var>description</var> is the same as in the
6398 daemon starting message.
6406 <heading>Cron jobs</heading>
6409 Packages must not modify the configuration file
6410 <file>/etc/crontab</file>, and they must not modify the files in
6411 <file>/var/spool/cron/crontabs</file>.</p>
6414 If a package wants to install a job that has to be executed
6415 via cron, it should place a file with the name of the
6416 package in one or more of the following directories:
6417 <example compact="compact">
6423 As these directory names imply, the files within them are
6424 executed on an hourly, daily, weekly, or monthly basis,
6425 respectively. The exact times are listed in
6426 <file>/etc/crontab</file>.</p>
6429 All files installed in any of these directories must be
6430 scripts (e.g., shell scripts or Perl scripts) so that they
6431 can easily be modified by the local system administrator.
6432 In addition, they must be treated as configuration files.
6436 If a certain job has to be executed at some other frequency or
6437 at a specific time, the package should install a file
6438 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6439 same syntax as <file>/etc/crontab</file> and is processed by
6440 <prgn>cron</prgn> automatically. The file must also be
6441 treated as a configuration file. (Note that entries in the
6442 <file>/etc/cron.d</file> directory are not handled by
6443 <prgn>anacron</prgn>. Thus, you should only use this
6444 directory for jobs which may be skipped if the system is not
6448 The scripts or crontab entries in these directories should
6449 check if all necessary programs are installed before they
6450 try to execute them. Otherwise, problems will arise when a
6451 package was removed but not purged since configuration files
6452 are kept on the system in this situation.</p>
6456 <heading>Menus</heading>
6459 The Debian <tt>menu</tt> package provides a standard
6460 interface between packages providing applications and
6461 <em>menu programs</em> (either X window managers or
6462 text-based menu programs such as <prgn>pdmenu</prgn>).
6466 All packages that provide applications that need not be
6467 passed any special command line arguments for normal
6468 operation should register a menu entry for those
6469 applications, so that users of the <tt>menu</tt> package
6470 will automatically get menu entries in their window
6471 managers, as well in shells like <tt>pdmenu</tt>.
6475 Menu entries should follow the current menu policy.
6479 The menu policy can be found in the <tt>menu-policy</tt>
6480 files in the <tt>debian-policy</tt> package.
6481 It is also available from the Debian web mirrors at
6482 <tt><url name="/doc/packaging-manuals/menu-policy/"
6483 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6487 Please also refer to the <em>Debian Menu System</em>
6488 documentation that comes with the <package>menu</package>
6489 package for information about how to register your
6495 <heading>Multimedia handlers</heading>
6498 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6499 is a mechanism for encoding files and data streams and
6500 providing meta-information about them, in particular their
6501 type (e.g. audio or video) and format (e.g. PNG, HTML,
6506 Registration of MIME type handlers allows programs like mail
6507 user agents and web browsers to invoke these handlers to
6508 view, edit or display MIME types they don't support directly.
6512 Packages which provide the ability to view/show/play,
6513 compose, edit or print MIME types should register themselves
6514 as such following the current MIME support policy.
6518 The MIME support policy can be found in the <tt>mime-policy</tt>
6519 files in the <tt>debian-policy</tt> package.
6520 It is also available from the Debian web mirrors at
6521 <tt><url name="/doc/packaging-manuals/mime-policy/"
6522 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6528 <heading>Keyboard configuration</heading>
6531 To achieve a consistent keyboard configuration so that all
6532 applications interpret a keyboard event the same way, all
6533 programs in the Debian distribution must be configured to
6534 comply with the following guidelines.
6538 The following keys must have the specified interpretations:
6541 <tag><tt><--</tt></tag>
6542 <item>delete the character to the left of the cursor</item>
6544 <tag><tt>Delete</tt></tag>
6545 <item>delete the character to the right of the cursor</item>
6547 <tag><tt>Control+H</tt></tag>
6548 <item>emacs: the help prefix</item>
6551 The interpretation of any keyboard events should be
6552 independent of the terminal that is used, be it a virtual
6553 console, an X terminal emulator, an rlogin/telnet session,
6558 The following list explains how the different programs
6559 should be set up to achieve this:
6565 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6569 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6573 X translations are set up to make
6574 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6575 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6576 is the vt220 escape code for the "delete character"
6577 key). This must be done by loading the X resources
6578 using <prgn>xrdb</prgn> on all local X displays, not
6579 using the application defaults, so that the
6580 translation resources used correspond to the
6581 <prgn>xmodmap</prgn> settings.
6585 The Linux console is configured to make
6586 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6587 generate <tt>ESC [ 3 ~</tt>.
6591 X applications are configured so that <tt><</tt>
6592 deletes left, and <tt>Delete</tt> deletes right. Motif
6593 applications already work like this.
6597 Terminals should have <tt>stty erase ^?</tt> .
6601 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6602 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6603 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6607 Emacs is programmed to map <tt>KB_Backspace</tt> or
6608 the <tt>stty erase</tt> character to
6609 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6610 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6611 <tt>^H</tt> to <tt>help</tt> as always.
6615 Other applications use the <tt>stty erase</tt>
6616 character and <tt>kdch1</tt> for the two delete keys,
6617 with ASCII DEL being "delete previous character" and
6618 <tt>kdch1</tt> being "delete character under
6626 This will solve the problem except for the following
6633 Some terminals have a <tt><--</tt> key that cannot
6634 be made to produce anything except <tt>^H</tt>. On
6635 these terminals Emacs help will be unavailable on
6636 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6637 character takes precedence in Emacs, and has been set
6638 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6639 available) can be used instead.
6643 Some operating systems use <tt>^H</tt> for <tt>stty
6644 erase</tt>. However, modern telnet versions and all
6645 rlogin versions propagate <tt>stty</tt> settings, and
6646 almost all UNIX versions honour <tt>stty erase</tt>.
6647 Where the <tt>stty</tt> settings are not propagated
6648 correctly, things can be made to work by using
6649 <tt>stty</tt> manually.
6653 Some systems (including previous Debian versions) use
6654 <prgn>xmodmap</prgn> to arrange for both
6655 <tt><--</tt> and <tt>Delete</tt> to generate
6656 <tt>KB_Delete</tt>. We can change the behavior of
6657 their X clients using the same X resources that we use
6658 to do it for our own clients, or configure our clients
6659 using their resources when things are the other way
6660 around. On displays configured like this
6661 <tt>Delete</tt> will not work, but <tt><--</tt>
6666 Some operating systems have different <tt>kdch1</tt>
6667 settings in their <tt>terminfo</tt> database for
6668 <tt>xterm</tt> and others. On these systems the
6669 <tt>Delete</tt> key will not work correctly when you
6670 log in from a system conforming to our policy, but
6671 <tt><--</tt> will.
6678 <heading>Environment variables</heading>
6681 A program must not depend on environment variables to get
6682 reasonable defaults. (That's because these environment
6683 variables would have to be set in a system-wide
6684 configuration file like <file>/etc/profile</file>, which is not
6685 supported by all shells.)
6689 If a program usually depends on environment variables for its
6690 configuration, the program should be changed to fall back to
6691 a reasonable default configuration if these environment
6692 variables are not present. If this cannot be done easily
6693 (e.g., if the source code of a non-free program is not
6694 available), the program must be replaced by a small
6695 "wrapper" shell script which sets the environment variables
6696 if they are not already defined, and calls the original program.
6700 Here is an example of a wrapper script for this purpose:
6702 <example compact="compact">
6704 BAR=${BAR:-/var/lib/fubar}
6706 exec /usr/lib/foo/foo "$@"
6711 Furthermore, as <file>/etc/profile</file> is a configuration
6712 file of the <prgn>base-files</prgn> package, other packages must
6713 not put any environment variables or other commands into that
6718 <sect id="doc-base">
6719 <heading>Registering Documents using doc-base</heading>
6722 The <package>doc-base</package> package implements a
6723 flexible mechanism for handling and presenting
6724 documentation. The recommended practice is for every Debian
6725 package that provides online documentation (other than just
6726 manual pages) to register these documents with
6727 <package>doc-base</package> by installing a
6728 <package>doc-base</package> control file via the
6729 <prgn/install-docs/ script at installation time and
6730 de-register the manuals again when the package is removed.
6733 Please refer to the documentation that comes with the
6734 <package>doc-base</package> package for information and
6743 <heading>Files</heading>
6746 <heading>Binaries</heading>
6749 Two different packages must not install programs with
6750 different functionality but with the same filenames. (The
6751 case of two programs having the same functionality but
6752 different implementations is handled via "alternatives" or
6753 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6754 <ref id="conflicts"> respectively.) If this case happens,
6755 one of the programs must be renamed. The maintainers should
6756 report this to the <tt>debian-devel</tt> mailing list and
6757 try to find a consensus about which program will have to be
6758 renamed. If a consensus cannot be reached, <em>both</em>
6759 programs must be renamed.
6763 By default, when a package is being built, any binaries
6764 created should include debugging information, as well as
6765 being compiled with optimization. You should also turn on
6766 as many reasonable compilation warnings as possible; this
6767 makes life easier for porters, who can then look at build
6768 logs for possible problems. For the C programming language,
6769 this means the following compilation parameters should be
6771 <example compact="compact">
6773 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6775 INSTALL = install -s # (or use strip on the files in debian/tmp)
6780 Note that by default all installed binaries should be stripped,
6781 either by using the <tt>-s</tt> flag to
6782 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6783 the binaries after they have been copied into
6784 <file>debian/tmp</file> but before the tree is made into a
6789 Although binaries in the build tree should be compiled with
6790 debugging information by default, it can often be difficult to
6791 debug programs if they are also subjected to compiler
6792 optimization. For this reason, it is recommended to support the
6793 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
6794 (see <ref id="debianrules-options">). This variable can contain
6795 several flags to change how a package is compiled and built.
6799 It is up to the package maintainer to decide what
6800 compilation options are best for the package. Certain
6801 binaries (such as computationally-intensive programs) will
6802 function better with certain flags (<tt>-O3</tt>, for
6803 example); feel free to use them. Please use good judgment
6804 here. Don't use flags for the sake of it; only use them
6805 if there is good reason to do so. Feel free to override
6806 the upstream author's ideas about which compilation
6807 options are best: they are often inappropriate for our
6813 <sect id="libraries">
6814 <heading>Libraries</heading>
6817 If the package is <strong>architecture: any</strong>, then
6818 the shared library compilation and linking flags must have
6819 <tt>-fPIC</tt>, or the package shall not build on some of
6820 the supported architectures<footnote>
6822 If you are using GCC, <tt>-fPIC</tt> produces code with
6823 relocatable position independent code, which is required for
6824 most architectures to create a shared library, with i386 and
6825 perhaps some others where non position independent code is
6826 permitted in a shared library.
6829 Position independent code may have a performance penalty,
6830 especially on <tt>i386</tt>. However, in most cases the
6831 speed penalty must be measured against the memory wasted on
6832 the few architectures where non position independent code is
6835 </footnote>. Any exception to this rule must be discussed on
6836 the mailing list <em>debian-devel@lists.debian.org</em>, and
6837 a rough consensus obtained. The reasons for not compiling
6838 with <tt>-fPIC</tt> flag must be recorded in the file
6839 <tt>README.Debian</tt>, and care must be taken to either
6840 restrict the architecture or arrange for <tt>-fPIC</tt> to
6841 be used on architectures where it is required.<footnote>
6843 Some of the reasons why this might be required is if the
6844 library contains hand crafted assembly code that is not
6845 relocatable, the speed penalty is excessive for compute
6846 intensive libs, and similar reasons.
6851 As to the static libraries, the common case is not to have
6852 relocatable code, since there is no benefit, unless in specific
6853 cases; therefore the static version must not be compiled
6854 with the <tt>-fPIC</tt> flag. Any exception to this rule
6855 should be discussed on the mailing list
6856 <em>debian-devel@lists.debian.org</em>, and the reasons for
6857 compiling with the <tt>-fPIC</tt> flag must be recorded in
6858 the file <tt>README.Debian</tt>. <footnote>
6860 Some of the reasons for linking static libraries with
6861 the <tt>-fPIC</tt> flag are if, for example, one needs a
6862 Perl API for a library that is under rapid development,
6863 and has an unstable API, so shared libraries are
6864 pointless at this phase of the library's development. In
6865 that case, since Perl needs a library with relocatable
6866 code, it may make sense to create a static library with
6867 relocatable code. Another reason cited is if you are
6868 distilling various libraries into a common shared
6869 library, like <tt>mklibs</tt> does in the Debian
6875 In other words, if both a shared and a static library is
6876 being built, each source unit (<tt>*.c</tt>, for example,
6877 for C files) will need to be compiled twice, for the normal
6881 You must specify the gcc option <tt>-D_REENTRANT</tt>
6882 when building a library (either static or shared) to make
6883 the library compatible with LinuxThreads.
6887 Although not enforced by the build tools, shared libraries
6888 must be linked against all libraries that they use symbols from
6889 in the same way that binaries are. This ensures the correct
6890 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
6891 system and guarantees that all libraries can be safely opened
6892 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
6893 option <tt>-Wl,-z,defs</tt> when building a shared library.
6894 Since this option enforces symbol resolution at build time,
6895 a missing library reference will be caught early as a fatal
6900 All installed shared libraries should be stripped with
6901 <example compact="compact">
6902 strip --strip-unneeded <var>your-lib</var>
6904 (The option <tt>--strip-unneeded</tt> makes
6905 <prgn>strip</prgn> remove only the symbols which aren't
6906 needed for relocation processing.) Shared libraries can
6907 function perfectly well when stripped, since the symbols for
6908 dynamic linking are in a separate part of the ELF object
6910 You might also want to use the options
6911 <tt>--remove-section=.comment</tt> and
6912 <tt>--remove-section=.note</tt> on both shared libraries
6913 and executables, and <tt>--strip-debug</tt> on static
6919 Note that under some circumstances it may be useful to
6920 install a shared library unstripped, for example when
6921 building a separate package to support debugging.
6925 Shared object files (often <file>.so</file> files) that are not
6926 public libraries, that is, they are not meant to be linked
6927 to by third party executables (binaries of other packages),
6928 should be installed in subdirectories of the
6929 <file>/usr/lib</file> directory. Such files are exempt from the
6930 rules that govern ordinary shared libraries, except that
6931 they must not be installed executable and should be
6933 A common example are the so-called "plug-ins",
6934 internal shared objects that are dynamically loaded by
6935 programs using <manref name="dlopen" section="3">.
6940 Packages containing shared libraries that may be linked to
6941 by other packages' binaries, but which for some
6942 <em>compelling</em> reason can not be installed in
6943 <file>/usr/lib</file> directory, may install the shared library
6944 files in subdirectories of the <file>/usr/lib</file> directory,
6945 in which case they should arrange to add that directory in
6946 <file>/etc/ld.so.conf</file> in the package's post-installation
6947 script, and remove it in the package's post-removal script.
6951 An ever increasing number of packages are using
6952 <prgn>libtool</prgn> to do their linking. The latest GNU
6953 libtools (>= 1.3a) can take advantage of the metadata in the
6954 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
6955 files). The main advantage of <prgn>libtool</prgn>'s
6956 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
6957 store and subsequently access metadata with respect to the
6958 libraries it builds. <prgn>libtool</prgn> will search for
6959 those files, which contain a lot of useful information about
6960 a library (such as library dependency information for static
6961 linking). Also, they're <em>essential</em> for programs
6962 using <tt>libltdl</tt>.<footnote>
6963 Although <prgn>libtool</prgn> is fully capable of
6964 linking against shared libraries which don't have
6965 <tt>.la</tt> files, as it is a mere shell script it can
6966 add considerably to the build time of a
6967 <prgn>libtool</prgn>-using package if that shell script
6968 has to derive all this information from first principles
6969 for each library every time it is linked. With the
6970 advent of <prgn>libtool</prgn> version 1.4 (and to a
6971 lesser extent <prgn>libtool</prgn> version 1.3), the
6972 <file>.la</file> files also store information about
6973 inter-library dependencies which cannot necessarily be
6974 derived after the <file>.la</file> file is deleted.
6979 Packages that use <prgn>libtool</prgn> to create shared
6980 libraries should include the <file>.la</file> files in the
6981 <tt>-dev</tt> package, unless the package relies on
6982 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
6983 the <tt>.la</tt> files must go in the run-time library
6988 You must make sure that you use only released versions of
6989 shared libraries to build your packages; otherwise other
6990 users will not be able to run your binaries
6991 properly. Producing source packages that depend on
6992 unreleased compilers is also usually a bad
6999 <heading>Shared libraries</heading>
7001 This section has moved to <ref id="sharedlibs">.
7007 <heading>Scripts</heading>
7010 All command scripts, including the package maintainer
7011 scripts inside the package and used by <prgn>dpkg</prgn>,
7012 should have a <tt>#!</tt> line naming the shell to be used
7017 In the case of Perl scripts this should be
7018 <tt>#!/usr/bin/perl</tt>.
7022 When scripts are installed into a directory in the system
7023 PATH, the script name should not include an extension such
7024 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7025 language currently used to implement it.
7028 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
7029 should almost certainly start with <tt>set -e</tt> so that
7030 errors are detected. Every script should use
7031 <tt>set -e</tt> or check the exit status of <em>every</em>
7036 Scripts may assume that <file>/bin/sh</file> implements the
7037 SUSv3 Shell Command Language<footnote>
7038 Single UNIX Specification, version 3, which is also IEEE
7039 1003.1-2004 (POSIX), and is available on the World Wide Web
7040 from <url id="http://www.unix.org/version3/online.html"
7041 name="The Open Group"> after free
7042 registration.</footnote>
7043 plus the following additional features not mandated by
7045 These features are in widespread use in the Linux community
7046 and are implemented in all of bash, dash, and ksh, the most
7047 common shells users may wish to use as <file>/bin/sh</file>.
7050 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7051 must not generate a newline.</item>
7052 <item><tt>test</tt>, if implemented as a shell built-in, must
7053 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7055 <item><tt>local</tt> to create a scoped variable must be
7056 supported; however, <tt>local</tt> may or may not preserve
7057 the variable value from an outer scope and may or may not
7058 support arguments more complex than simple variables. Only
7070 If a shell script requires non-SUSv3 features from the shell
7071 interpreter other than those listed above, the appropriate shell
7072 must be specified in the first line of the script (e.g.,
7073 <tt>#!/bin/bash</tt>) and the package must depend on the package
7074 providing the shell (unless the shell package is marked
7075 "Essential", as in the case of <prgn>bash</prgn>).
7079 You may wish to restrict your script to SUSv3 features plus the
7080 above set when possible so that it may use <file>/bin/sh</file>
7081 as its interpreter. If your script works with <prgn>dash</prgn>
7082 (originally called <prgn>ash</prgn>), it probably complies with
7083 the above requirements, but if you are in doubt, use
7084 <file>/bin/bash</file>.
7088 Perl scripts should check for errors when making any
7089 system calls, including <tt>open</tt>, <tt>print</tt>,
7090 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7094 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7095 scripting languages. See <em>Csh Programming Considered
7096 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7097 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7098 If an upstream package comes with <prgn>csh</prgn> scripts
7099 then you must make sure that they start with
7100 <tt>#!/bin/csh</tt> and make your package depend on the
7101 <prgn>c-shell</prgn> virtual package.
7105 Any scripts which create files in world-writeable
7106 directories (e.g., in <file>/tmp</file>) must use a
7107 mechanism which will fail atomically if a file with the same
7108 name already exists.
7112 The Debian base system provides the <prgn>tempfile</prgn>
7113 and <prgn>mktemp</prgn> utilities for use by scripts for
7120 <heading>Symbolic links</heading>
7123 In general, symbolic links within a top-level directory
7124 should be relative, and symbolic links pointing from one
7125 top-level directory into another should be absolute. (A
7126 top-level directory is a sub-directory of the root
7127 directory <file>/</file>.)
7131 In addition, symbolic links should be specified as short as
7132 possible, i.e., link targets like <file>foo/../bar</file> are
7137 Note that when creating a relative link using
7138 <prgn>ln</prgn> it is not necessary for the target of the
7139 link to exist relative to the working directory you're
7140 running <prgn>ln</prgn> from, nor is it necessary to change
7141 directory to the directory where the link is to be made.
7142 Simply include the string that should appear as the target
7143 of the link (this will be a pathname relative to the
7144 directory in which the link resides) as the first argument
7149 For example, in your <prgn>Makefile</prgn> or
7150 <file>debian/rules</file>, you can do things like:
7151 <example compact="compact">
7152 ln -fs gcc $(prefix)/bin/cc
7153 ln -fs gcc debian/tmp/usr/bin/cc
7154 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7155 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7160 A symbolic link pointing to a compressed file should always
7161 have the same file extension as the referenced file. (For
7162 example, if a file <file>foo.gz</file> is referenced by a
7163 symbolic link, the filename of the link has to end with
7164 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7169 <heading>Device files</heading>
7172 Packages must not include device files in the package file
7177 If a package needs any special device files that are not
7178 included in the base system, it must call
7179 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7180 after notifying the user<footnote>
7181 This notification could be done via a (low-priority)
7182 debconf message, or an echo (printf) statement.
7187 Packages must not remove any device files in the
7188 <prgn>postrm</prgn> or any other script. This is left to the
7189 system administrator.
7193 Debian uses the serial devices
7194 <file>/dev/ttyS*</file>. Programs using the old
7195 <file>/dev/cu*</file> devices should be changed to use
7196 <file>/dev/ttyS*</file>.
7200 <sect id="config-files">
7201 <heading>Configuration files</heading>
7204 <heading>Definitions</heading>
7208 <tag>configuration file</tag>
7210 A file that affects the operation of a program, or
7211 provides site- or host-specific information, or
7212 otherwise customizes the behavior of a program.
7213 Typically, configuration files are intended to be
7214 modified by the system administrator (if needed or
7215 desired) to conform to local policy or to provide
7216 more useful site-specific behavior.
7219 <tag><tt>conffile</tt></tag>
7221 A file listed in a package's <tt>conffiles</tt>
7222 file, and is treated specially by <prgn>dpkg</prgn>
7223 (see <ref id="configdetails">).
7229 The distinction between these two is important; they are
7230 not interchangeable concepts. Almost all
7231 <tt>conffile</tt>s are configuration files, but many
7232 configuration files are not <tt>conffiles</tt>.
7236 As noted elsewhere, <file>/etc/init.d</file> scripts,
7237 <file>/etc/default</file> files, scripts installed in
7238 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7239 configuration installed in <file>/etc/cron.d</file> must be
7240 treated as configuration files. In general, any script that
7241 embeds configuration information is de-facto a configuration
7242 file and should be treated as such.
7247 <heading>Location</heading>
7250 Any configuration files created or used by your package
7251 must reside in <file>/etc</file>. If there are several,
7252 consider creating a subdirectory of <file>/etc</file>
7253 named after your package.
7257 If your package creates or uses configuration files
7258 outside of <file>/etc</file>, and it is not feasible to modify
7259 the package to use <file>/etc</file> directly, put the files
7260 in <file>/etc</file> and create symbolic links to those files
7261 from the location that the package requires.
7266 <heading>Behavior</heading>
7269 Configuration file handling must conform to the following
7271 <list compact="compact">
7273 local changes must be preserved during a package
7277 configuration files must be preserved when the
7278 package is removed, and only deleted when the
7285 The easy way to achieve this behavior is to make the
7286 configuration file a <tt>conffile</tt>. This is
7287 appropriate only if it is possible to distribute a default
7288 version that will work for most installations, although
7289 some system administrators may choose to modify it. This
7290 implies that the default version will be part of the
7291 package distribution, and must not be modified by the
7292 maintainer scripts during installation (or at any other
7297 In order to ensure that local changes are preserved
7298 correctly, no package may contain or make hard links to
7299 conffiles.<footnote>
7300 Rationale: There are two problems with hard links.
7301 The first is that some editors break the link while
7302 editing one of the files, so that the two files may
7303 unwittingly become unlinked and different. The second
7304 is that <prgn>dpkg</prgn> might break the hard link
7305 while upgrading <tt>conffile</tt>s.
7310 The other way to do it is via the maintainer scripts. In
7311 this case, the configuration file must not be listed as a
7312 <tt>conffile</tt> and must not be part of the package
7313 distribution. If the existence of a file is required for
7314 the package to be sensibly configured it is the
7315 responsibility of the package maintainer to provide
7316 maintainer scripts which correctly create, update and
7317 maintain the file and remove it on purge. (See <ref
7318 id="maintainerscripts"> for more information.) These
7319 scripts must be idempotent (i.e., must work correctly if
7320 <prgn>dpkg</prgn> needs to re-run them due to errors
7321 during installation or removal), must cope with all the
7322 variety of ways <prgn>dpkg</prgn> can call maintainer
7323 scripts, must not overwrite or otherwise mangle the user's
7324 configuration without asking, must not ask unnecessary
7325 questions (particularly during upgrades), and must
7326 otherwise be good citizens.
7330 The scripts are not required to configure every possible
7331 option for the package, but only those necessary to get
7332 the package running on a given system. Ideally the
7333 sysadmin should not have to do any configuration other
7334 than that done (semi-)automatically by the
7335 <prgn>postinst</prgn> script.
7339 A common practice is to create a script called
7340 <file><var>package</var>-configure</file> and have the
7341 package's <prgn>postinst</prgn> call it if and only if the
7342 configuration file does not already exist. In certain
7343 cases it is useful for there to be an example or template
7344 file which the maintainer scripts use. Such files should
7345 be in <file>/usr/share/<var>package</var></file> or
7346 <file>/usr/lib/<var>package</var></file> (depending on whether
7347 they are architecture-independent or not). There should
7348 be symbolic links to them from
7349 <file>/usr/share/doc/<var>package</var>/examples</file> if
7350 they are examples, and should be perfectly ordinary
7351 <prgn>dpkg</prgn>-handled files (<em>not</em>
7352 configuration files).
7356 These two styles of configuration file handling must
7357 not be mixed, for that way lies madness:
7358 <prgn>dpkg</prgn> will ask about overwriting the file
7359 every time the package is upgraded.
7364 <heading>Sharing configuration files</heading>
7367 Packages which specify the same file as a
7368 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7369 with each other. (This is an instance of the general rule
7370 about not sharing files. Note that neither alternatives
7371 nor diversions are likely to be appropriate in this case;
7372 in particular, <prgn>dpkg</prgn> does not handle diverted
7373 <tt>conffile</tt>s well.)
7377 The maintainer scripts must not alter a <tt>conffile</tt>
7378 of <em>any</em> package, including the one the scripts
7383 If two or more packages use the same configuration file
7384 and it is reasonable for both to be installed at the same
7385 time, one of these packages must be defined as
7386 <em>owner</em> of the configuration file, i.e., it will be
7387 the package which handles that file as a configuration
7388 file. Other packages that use the configuration file must
7389 depend on the owning package if they require the
7390 configuration file to operate. If the other package will
7391 use the configuration file if present, but is capable of
7392 operating without it, no dependency need be declared.
7396 If it is desirable for two or more related packages to
7397 share a configuration file <em>and</em> for all of the
7398 related packages to be able to modify that configuration
7399 file, then the following should be done:
7400 <enumlist compact="compact">
7402 One of the related packages (the "owning" package)
7403 will manage the configuration file with maintainer
7404 scripts as described in the previous section.
7407 The owning package should also provide a program
7408 that the other packages may use to modify the
7412 The related packages must use the provided program
7413 to make any desired modifications to the
7414 configuration file. They should either depend on
7415 the core package to guarantee that the configuration
7416 modifier program is available or accept gracefully
7417 that they cannot modify the configuration file if it
7418 is not. (This is in addition to the fact that the
7419 configuration file may not even be present in the
7426 Sometimes it's appropriate to create a new package which
7427 provides the basic infrastructure for the other packages
7428 and which manages the shared configuration files. (The
7429 <tt>sgml-base</tt> package is a good example.)
7434 <heading>User configuration files ("dotfiles")</heading>
7437 The files in <file>/etc/skel</file> will automatically be
7438 copied into new user accounts by <prgn>adduser</prgn>.
7439 No other program should reference the files in
7440 <file>/etc/skel</file>.
7444 Therefore, if a program needs a dotfile to exist in
7445 advance in <file>$HOME</file> to work sensibly, that dotfile
7446 should be installed in <file>/etc/skel</file> and treated as a
7451 However, programs that require dotfiles in order to
7452 operate sensibly are a bad thing, unless they do create
7453 the dotfiles themselves automatically.
7457 Furthermore, programs should be configured by the Debian
7458 default installation to behave as closely to the upstream
7459 default behavior as possible.
7463 Therefore, if a program in a Debian package needs to be
7464 configured in some way in order to operate sensibly, that
7465 should be done using a site-wide configuration file placed
7466 in <file>/etc</file>. Only if the program doesn't support a
7467 site-wide default configuration and the package maintainer
7468 doesn't have time to add it may a default per-user file be
7469 placed in <file>/etc/skel</file>.
7473 <file>/etc/skel</file> should be as empty as we can make it.
7474 This is particularly true because there is no easy (or
7475 necessarily desirable) mechanism for ensuring that the
7476 appropriate dotfiles are copied into the accounts of
7477 existing users when a package is installed.
7483 <heading>Log files</heading>
7485 Log files should usually be named
7486 <file>/var/log/<var>package</var>.log</file>. If you have many
7487 log files, or need a separate directory for permission
7488 reasons (<file>/var/log</file> is writable only by
7489 <file>root</file>), you should usually create a directory named
7490 <file>/var/log/<var>package</var></file> and place your log
7495 Log files must be rotated occasionally so that they don't
7496 grow indefinitely; the best way to do this is to drop a log
7497 rotation configuration file into the directory
7498 <file>/etc/logrotate.d</file> and use the facilities provided by
7499 logrotate.<footnote>
7501 The traditional approach to log files has been to set up
7502 <em>ad hoc</em> log rotation schemes using simple shell
7503 scripts and cron. While this approach is highly
7504 customizable, it requires quite a lot of sysadmin work.
7505 Even though the original Debian system helped a little
7506 by automatically installing a system which can be used
7507 as a template, this was deemed not enough.
7511 The use of <prgn>logrotate</prgn>, a program developed
7512 by Red Hat, is better, as it centralizes log management.
7513 It has both a configuration file
7514 (<file>/etc/logrotate.conf</file>) and a directory where
7515 packages can drop their individual log rotation
7516 configurations (<file>/etc/logrotate.d</file>).
7519 Here is a good example for a logrotate config
7520 file (for more information see <manref name="logrotate"
7522 <example compact="compact">
7523 /var/log/foo/*.log {
7528 /etc/init.d/foo force-reload
7532 This rotates all files under <file>/var/log/foo</file>, saves 12
7533 compressed generations, and forces the daemon to reload its
7534 configuration information after the log rotation.
7538 Log files should be removed when the package is
7539 purged (but not when it is only removed). This should be
7540 done by the <prgn>postrm</prgn> script when it is called
7541 with the argument <tt>purge</tt> (see <ref
7542 id="removedetails">).
7547 <heading>Permissions and owners</heading>
7550 The rules in this section are guidelines for general use.
7551 If necessary you may deviate from the details below.
7552 However, if you do so you must make sure that what is done
7553 is secure and you should try to be as consistent as possible
7554 with the rest of the system. You should probably also
7555 discuss it on <prgn>debian-devel</prgn> first.
7559 Files should be owned by <tt>root:root</tt>, and made
7560 writable only by the owner and universally readable (and
7561 executable, if appropriate), that is mode 644 or 755.
7565 Directories should be mode 755 or (for group-writability)
7566 mode 2775. The ownership of the directory should be
7567 consistent with its mode: if a directory is mode 2775, it
7568 should be owned by the group that needs write access to
7571 When a package is upgraded, and the owner or permissions
7572 of a file included in the package has changed, dpkg
7573 arranges for the ownership and permissions to be
7574 correctly set upon installation. However, this does not
7575 extend to directories; the permissions and ownership of
7576 directories already on the system does not change on
7577 install or upgrade of packages. This makes sense, since
7578 otherwise common directories like <tt>/usr</tt> would
7579 always be in flux. To correctly change permissions of a
7580 directory the package owns, explicit action is required,
7581 usually in the <tt>postinst</tt> script. Care must be
7582 taken to handle downgrades as well, in that case.
7589 Setuid and setgid executables should be mode 4755 or 2755
7590 respectively, and owned by the appropriate user or group.
7591 They should not be made unreadable (modes like 4711 or
7592 2711 or even 4111); doing so achieves no extra security,
7593 because anyone can find the binary in the freely available
7594 Debian package; it is merely inconvenient. For the same
7595 reason you should not restrict read or execute permissions
7596 on non-set-id executables.
7600 Some setuid programs need to be restricted to particular
7601 sets of users, using file permissions. In this case they
7602 should be owned by the uid to which they are set-id, and by
7603 the group which should be allowed to execute them. They
7604 should have mode 4754; again there is no point in making
7605 them unreadable to those users who must not be allowed to
7610 It is possible to arrange that the system administrator can
7611 reconfigure the package to correspond to their local
7612 security policy by changing the permissions on a binary:
7613 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7614 described below.<footnote>
7615 Ordinary files installed by <prgn>dpkg</prgn> (as
7616 opposed to <tt>conffile</tt>s and other similar objects)
7617 normally have their permissions reset to the distributed
7618 permissions when the package is reinstalled. However,
7619 the use of <prgn>dpkg-statoverride</prgn> overrides this
7620 default behavior. If you use this method, you should
7621 remember to describe <prgn>dpkg-statoverride</prgn> in
7622 the package documentation; being a relatively new
7623 addition to Debian, it is probably not yet well-known.
7625 Another method you should consider is to create a group for
7626 people allowed to use the program(s) and make any setuid
7627 executables executable only by that group.
7631 If you need to create a new user or group for your package
7632 there are two possibilities. Firstly, you may need to
7633 make some files in the binary package be owned by this
7634 user or group, or you may need to compile the user or
7635 group id (rather than just the name) into the binary
7636 (though this latter should be avoided if possible, as in
7637 this case you need a statically allocated id).</p>
7640 If you need a statically allocated id, you must ask for a
7641 user or group id from the <tt>base-passwd</tt> maintainer,
7642 and must not release the package until you have been
7643 allocated one. Once you have been allocated one you must
7644 either make the package depend on a version of the
7645 <tt>base-passwd</tt> package with the id present in
7646 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7647 your package to create the user or group itself with the
7648 correct id (using <tt>adduser</tt>) in its
7649 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7650 the <prgn>postinst</prgn> is to be preferred if it is
7651 possible, otherwise a pre-dependency will be needed on the
7652 <tt>adduser</tt> package.)
7656 On the other hand, the program might be able to determine
7657 the uid or gid from the user or group name at runtime, so
7658 that a dynamically allocated id can be used. In this case
7659 you should choose an appropriate user or group name,
7660 discussing this on <prgn>debian-devel</prgn> and checking
7661 with the <package/base-passwd/ maintainer that it is unique and that
7662 they do not wish you to use a statically allocated id
7663 instead. When this has been checked you must arrange for
7664 your package to create the user or group if necessary using
7665 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7666 <prgn>postinst</prgn> script (again, the latter is to be
7667 preferred if it is possible).
7671 Note that changing the numeric value of an id associated
7672 with a name is very difficult, and involves searching the
7673 file system for all appropriate files. You need to think
7674 carefully whether a static or dynamic id is required, since
7675 changing your mind later will cause problems.
7678 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7680 This section is not intended as policy, but as a
7681 description of the use of <prgn>dpkg-statoverride</prgn>.
7685 If a system administrator wishes to have a file (or
7686 directory or other such thing) installed with owner and
7687 permissions different from those in the distributed Debian
7688 package, they can use the <prgn>dpkg-statoverride</prgn>
7689 program to instruct <prgn>dpkg</prgn> to use the different
7690 settings every time the file is installed. Thus the
7691 package maintainer should distribute the files with their
7692 normal permissions, and leave it for the system
7693 administrator to make any desired changes. For example, a
7694 daemon which is normally required to be setuid root, but
7695 in certain situations could be used without being setuid,
7696 should be installed setuid in the <tt>.deb</tt>. Then the
7697 local system administrator can change this if they wish.
7698 If there are two standard ways of doing it, the package
7699 maintainer can use <tt>debconf</tt> to find out the
7700 preference, and call <prgn>dpkg-statoverride</prgn> in the
7701 maintainer script if necessary to accommodate the system
7702 administrator's choice. Care must be taken during
7703 upgrades to not override an existing setting.
7707 Given the above, <prgn>dpkg-statoverride</prgn> is
7708 essentially a tool for system administrators and would not
7709 normally be needed in the maintainer scripts. There is
7710 one type of situation, though, where calls to
7711 <prgn>dpkg-statoverride</prgn> would be needed in the
7712 maintainer scripts, and that involves packages which use
7713 dynamically allocated user or group ids. In such a
7714 situation, something like the following idiom can be very
7715 helpful in the package's <prgn>postinst</prgn>, where
7716 <tt>sysuser</tt> is a dynamically allocated id:
7718 for i in /usr/bin/foo /usr/sbin/bar
7720 # only do something when no setting exists
7721 if ! dpkg-statoverride --list $i >/dev/null 2>&1
7723 #include: debconf processing, question about foo and bar
7724 if [ "$RET" = "true" ] ; then
7725 dpkg-statoverride --update --add sysuser root 4755 $i
7730 The corresponding <tt>dpkg-statoverride --remove</tt>
7731 calls can then be made unconditionally when the package is
7739 <chapt id="customized-programs">
7740 <heading>Customized programs</heading>
7742 <sect id="arch-spec">
7743 <heading>Architecture specification strings</heading>
7746 If a program needs to specify an <em>architecture specification
7747 string</em> in some place, it should select one of the
7748 strings provided by <tt>dpkg-architecture -L</tt>. The
7749 strings are in the format
7750 <tt><var>os</var>-<var>arch</var></tt>, though the OS part
7751 is sometimes elided, as when the OS is Linux.<footnote>
7752 <p>Currently, the strings are:
7753 i386 ia64 alpha amd64 armeb arm hppa m32r m68k mips
7754 mipsel powerpc ppc64 s390 s390x sh3 sh3eb sh4 sh4eb
7755 sparc darwin-i386 darwin-ia64 darwin-alpha darwin-amd64
7756 darwin-armeb darwin-arm darwin-hppa darwin-m32r
7757 darwin-m68k darwin-mips darwin-mipsel darwin-powerpc
7758 darwin-ppc64 darwin-s390 darwin-s390x darwin-sh3
7759 darwin-sh3eb darwin-sh4 darwin-sh4eb darwin-sparc
7760 freebsd-i386 freebsd-ia64 freebsd-alpha freebsd-amd64
7761 freebsd-armeb freebsd-arm freebsd-hppa freebsd-m32r
7762 freebsd-m68k freebsd-mips freebsd-mipsel freebsd-powerpc
7763 freebsd-ppc64 freebsd-s390 freebsd-s390x freebsd-sh3
7764 freebsd-sh3eb freebsd-sh4 freebsd-sh4eb freebsd-sparc
7765 kfreebsd-i386 kfreebsd-ia64 kfreebsd-alpha
7766 kfreebsd-amd64 kfreebsd-armeb kfreebsd-arm kfreebsd-hppa
7767 kfreebsd-m32r kfreebsd-m68k kfreebsd-mips
7768 kfreebsd-mipsel kfreebsd-powerpc kfreebsd-ppc64
7769 kfreebsd-s390 kfreebsd-s390x kfreebsd-sh3 kfreebsd-sh3eb
7770 kfreebsd-sh4 kfreebsd-sh4eb kfreebsd-sparc knetbsd-i386
7771 knetbsd-ia64 knetbsd-alpha knetbsd-amd64 knetbsd-armeb
7772 knetbsd-arm knetbsd-hppa knetbsd-m32r knetbsd-m68k
7773 knetbsd-mips knetbsd-mipsel knetbsd-powerpc
7774 knetbsd-ppc64 knetbsd-s390 knetbsd-s390x knetbsd-sh3
7775 knetbsd-sh3eb knetbsd-sh4 knetbsd-sh4eb knetbsd-sparc
7776 netbsd-i386 netbsd-ia64 netbsd-alpha netbsd-amd64
7777 netbsd-armeb netbsd-arm netbsd-hppa netbsd-m32r
7778 netbsd-m68k netbsd-mips netbsd-mipsel netbsd-powerpc
7779 netbsd-ppc64 netbsd-s390 netbsd-s390x netbsd-sh3
7780 netbsd-sh3eb netbsd-sh4 netbsd-sh4eb netbsd-sparc
7781 openbsd-i386 openbsd-ia64 openbsd-alpha openbsd-amd64
7782 openbsd-armeb openbsd-arm openbsd-hppa openbsd-m32r
7783 openbsd-m68k openbsd-mips openbsd-mipsel openbsd-powerpc
7784 openbsd-ppc64 openbsd-s390 openbsd-s390x openbsd-sh3
7785 openbsd-sh3eb openbsd-sh4 openbsd-sh4eb openbsd-sparc
7786 hurd-i386 hurd-ia64 hurd-alpha hurd-amd64 hurd-armeb
7787 hurd-arm hurd-hppa hurd-m32r hurd-m68k hurd-mips
7788 hurd-mipsel hurd-powerpc hurd-ppc64 hurd-s390 hurd-s390x
7789 hurd-sh3 hurd-sh3eb hurd-sh4 hurd-sh4eb hurd-sparc
7795 Note that we don't want to use
7796 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7797 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7798 since this would make our programs incompatible with other
7799 Linux distributions. We also don't use something like
7800 <tt><var>arch</var>-unknown-linux</tt>, since the
7801 <tt>unknown</tt> does not look very good.
7806 <heading>Daemons</heading>
7809 The configuration files <file>/etc/services</file>,
7810 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7811 by the <prgn>netbase</prgn> package and must not be modified
7816 If a package requires a new entry in one of these files, the
7817 maintainer should get in contact with the
7818 <prgn>netbase</prgn> maintainer, who will add the entries
7819 and release a new version of the <prgn>netbase</prgn>
7824 The configuration file <file>/etc/inetd.conf</file> must not be
7825 modified by the package's scripts except via the
7826 <prgn>update-inetd</prgn> script or the
7827 <file>DebianNet.pm</file> Perl module. See their documentation
7828 for details on how to add entries.
7832 If a package wants to install an example entry into
7833 <file>/etc/inetd.conf</file>, the entry must be preceded with
7834 exactly one hash character (<tt>#</tt>). Such lines are
7835 treated as "commented out by user" by the
7836 <prgn>update-inetd</prgn> script and are not changed or
7837 activated during package updates.
7842 <heading>Using pseudo-ttys and modifying wtmp, utmp and
7846 Some programs need to create pseudo-ttys. This should be done
7847 using Unix98 ptys if the C library supports it. The resulting
7848 program must not be installed setuid root, unless that
7849 is required for other functionality.
7853 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
7854 <file>/var/log/lastlog</file> must be installed writable by
7855 group <tt>utmp</tt>. Programs which need to modify those
7856 files must be installed setgid <tt>utmp</tt>.
7861 <heading>Editors and pagers</heading>
7864 Some programs have the ability to launch an editor or pager
7865 program to edit or display a text document. Since there are
7866 lots of different editors and pagers available in the Debian
7867 distribution, the system administrator and each user should
7868 have the possibility to choose their preferred editor and
7873 In addition, every program should choose a good default
7874 editor/pager if none is selected by the user or system
7879 Thus, every program that launches an editor or pager must
7880 use the EDITOR or PAGER environment variable to determine
7881 the editor or pager the user wishes to use. If these
7882 variables are not set, the programs <file>/usr/bin/editor</file>
7883 and <file>/usr/bin/pager</file> should be used, respectively.
7887 These two files are managed through the <prgn>dpkg</prgn>
7888 "alternatives" mechanism. Thus every package providing an
7889 editor or pager must call the
7890 <prgn>update-alternatives</prgn> script to register these
7895 If it is very hard to adapt a program to make use of the
7896 EDITOR or PAGER variables, that program may be configured to
7897 use <file>/usr/bin/sensible-editor</file> and
7898 <file>/usr/bin/sensible-pager</file> as the editor or pager
7899 program respectively. These are two scripts provided in the
7900 Debian base system that check the EDITOR and PAGER variables
7901 and launch the appropriate program, and fall back to
7902 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
7903 variable is not set.
7907 A program may also use the VISUAL environment variable to
7908 determine the user's choice of editor. If it exists, it
7909 should take precedence over EDITOR. This is in fact what
7910 <file>/usr/bin/sensible-editor</file> does.
7914 It is not required for a package to depend on
7915 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
7916 package to provide such virtual packages.<footnote>
7917 The Debian base system already provides an editor and a
7923 <sect id="web-appl">
7924 <heading>Web servers and applications</heading>
7927 This section describes the locations and URLs that should
7928 be used by all web servers and web applications in the
7935 Cgi-bin executable files are installed in the
7937 <example compact="compact">
7938 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
7940 and should be referred to as
7941 <example compact="compact">
7942 http://localhost/cgi-bin/<var>cgi-bin-name</var>
7948 <p>Access to HTML documents</p>
7951 HTML documents for a package are stored in
7952 <file>/usr/share/doc/<var>package</var></file>
7953 and can be referred to as
7954 <example compact="compact">
7955 http://localhost/doc/<var>package</var>/<var>filename</var>
7960 The web server should restrict access to the document
7961 tree so that only clients on the same host can read
7962 the documents. If the web server does not support such
7963 access controls, then it should not provide access at
7964 all, or ask about providing access during installation.
7969 <p>Access to images</p>
7971 It is recommended that images for a package be stored
7972 in <tt>/usr/share/images/<var>package</var></tt> and
7973 may be referred to through an alias <tt>/images/</tt>
7976 http://localhost/images/<package>/<filename>
7983 <p>Web Document Root</p>
7986 Web Applications should try to avoid storing files in
7987 the Web Document Root. Instead they should use the
7988 /usr/share/doc/<var>package</var> directory for
7989 documents and register the Web Application via the
7990 <package>doc-base</package> package. If access to the
7991 web document root is unavoidable then use
7992 <example compact="compact">
7995 as the Document Root. This might be just a symbolic
7996 link to the location where the system administrator
7997 has put the real document root.
8000 <item><p>Providing httpd and/or httpd-cgi</p>
8002 All web servers should provide the virtual package
8003 <tt>httpd</tt>. If a web server has CGI support it should
8004 provide <tt>httpd-cgi</tt> additionally.
8007 All web applications which do not contain CGI scripts should
8008 depend on <tt>httpd</tt>, all those web applications which
8009 <tt>do</tt> contain CGI scripts, should depend on
8017 <sect id="mail-transport-agents">
8018 <heading>Mail transport, delivery and user agents</heading>
8021 Debian packages which process electronic mail, whether mail
8022 user agents (MUAs) or mail transport agents (MTAs), must
8023 ensure that they are compatible with the configuration
8024 decisions below. Failure to do this may result in lost
8025 mail, broken <tt>From:</tt> lines, and other serious brain
8030 The mail spool is <file>/var/mail</file> and the interface to
8031 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8032 the FHS). On older systems, the mail spool may be
8033 physically located in <file>/var/spool/mail</file>, but all
8034 access to the mail spool should be via the
8035 <file>/var/mail</file> symlink. The mail spool is part of the
8036 base system and not part of the MTA package.
8040 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8041 programs (such as IMAP daemons) must lock the mailbox in an
8042 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8043 be combined with dot locking. To avoid deadlocks, a program
8044 should use <tt>fcntl()</tt> first and dot locking after
8045 this, or alternatively implement the two locking methods in
8046 a non blocking way<footnote>
8047 If it is not possible to establish both locks, the
8048 system shouldn't wait for the second lock to be
8049 established, but remove the first lock, wait a (random)
8050 time, and start over locking again.
8051 </footnote>. Using the functions <tt>maillock</tt> and
8052 <tt>mailunlock</tt> provided by the
8053 <tt>liblockfile*</tt><footnote>
8054 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8055 to use these functions.
8056 </footnote> packages is the recommended way to realize this.
8060 Mailboxes are generally mode 660
8061 <tt><var>user</var>:mail</tt> unless the system
8062 administrator has chosen otherwise. A MUA may remove a
8063 mailbox (unless it has nonstandard permissions) in which
8064 case the MTA or another MUA must recreate it if needed.
8065 Mailboxes must be writable by group mail.
8069 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8070 be setgid mail to do the locking mentioned above (and
8071 must obviously avoid accessing other users' mailboxes
8072 using this privilege).</p>
8075 <file>/etc/aliases</file> is the source file for the system mail
8076 aliases (e.g., postmaster, usenet, etc.), it is the one
8077 which the sysadmin and <prgn>postinst</prgn> scripts may
8078 edit. After <file>/etc/aliases</file> is edited the program or
8079 human editing it must call <prgn>newaliases</prgn>. All MTA
8080 packages must come with a <prgn>newaliases</prgn> program,
8081 even if it does nothing, but older MTA packages did not do
8082 this so programs should not fail if <prgn>newaliases</prgn>
8083 cannot be found. Note that because of this, all MTA
8084 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8085 <tt>Replaces: mail-transport-agent</tt> control file
8090 The convention of writing <tt>forward to
8091 <var>address</var></tt> in the mailbox itself is not
8092 supported. Use a <tt>.forward</tt> file instead.</p>
8095 The <prgn>rmail</prgn> program used by UUCP
8096 for incoming mail should be <file>/usr/sbin/rmail</file>.
8097 Likewise, <prgn>rsmtp</prgn>, for receiving
8098 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8102 If your package needs to know what hostname to use on (for
8103 example) outgoing news and mail messages which are generated
8104 locally, you should use the file <file>/etc/mailname</file>. It
8105 will contain the portion after the username and <tt>@</tt>
8106 (at) sign for email addresses of users on the machine
8107 (followed by a newline).
8111 Such a package should check for the existence of this file
8112 when it is being configured. If it exists, it should be
8113 used without comment, although an MTA's configuration script
8114 may wish to prompt the user even if it finds that this file
8115 exists. If the file does not exist, the package should
8116 prompt the user for the value (preferably using
8117 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8118 as well as using it in the package's configuration. The
8119 prompt should make it clear that the name will not just be
8120 used by that package. For example, in this situation the
8121 <tt>inn</tt> package could say something like:
8122 <example compact="compact">
8123 Please enter the "mail name" of your system. This is the
8124 hostname portion of the address to be shown on outgoing
8125 news and mail messages. The default is
8126 <var>syshostname</var>, your system's host name. Mail
8127 name ["<var>syshostname</var>"]:
8129 where <var>syshostname</var> is the output of <tt>hostname
8135 <heading>News system configuration</heading>
8138 All the configuration files related to the NNTP (news)
8139 servers and clients should be located under
8140 <file>/etc/news</file>.</p>
8143 There are some configuration issues that apply to a number
8144 of news clients and server packages on the machine. These
8148 <tag><file>/etc/news/organization</file></tag>
8150 A string which should appear as the
8151 organization header for all messages posted
8152 by NNTP clients on the machine
8155 <tag><file>/etc/news/server</file></tag>
8157 Contains the FQDN of the upstream NNTP
8158 server, or localhost if the local machine is
8163 Other global files may be added as required for cross-package news
8170 <heading>Programs for the X Window System</heading>
8173 <heading>Providing X support and package priorities</heading>
8176 Programs that can be configured with support for the X
8177 Window System must be configured to do so and must declare
8178 any package dependencies necessary to satisfy their
8179 runtime requirements when using the X Window System. If
8180 such a package is of higher priority than the X packages
8181 on which it depends, it is required that either the
8182 X-specific components be split into a separate package, or
8183 that an alternative version of the package, which includes
8184 X support, be provided, or that the package's priority be
8190 <heading>Packages providing an X server</heading>
8193 Packages that provide an X server that, directly or
8194 indirectly, communicates with real input and display
8195 hardware should declare in their control data that they
8196 provide the virtual package <tt>xserver</tt>.<footnote>
8197 This implements current practice, and provides an
8198 actual policy for usage of the <tt>xserver</tt>
8199 virtual package which appears in the virtual packages
8200 list. In a nutshell, X servers that interface
8201 directly with the display and input hardware or via
8202 another subsystem (e.g., GGI) should provide
8203 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8204 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8210 <heading>Packages providing a terminal emulator</heading>
8213 Packages that provide a terminal emulator for the X Window
8214 System which meet the criteria listed below should declare
8215 in their control data that they provide the virtual
8216 package <tt>x-terminal-emulator</tt>. They should also
8217 register themselves as an alternative for
8218 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8223 To be an <tt>x-terminal-emulator</tt>, a program must:
8224 <list compact="compact">
8226 Be able to emulate a DEC VT100 terminal, or a
8227 compatible terminal.
8231 Support the command-line option <tt>-e
8232 <var>command</var></tt>, which creates a new
8233 terminal window<footnote>
8234 "New terminal window" does not necessarily mean
8235 a new top-level X window directly parented by
8236 the window manager; it could, if the terminal
8237 emulator application were so coded, be a new
8238 "view" in a multiple-document interface (MDI).
8240 and runs the specified <var>command</var>,
8241 interpreting the entirety of the rest of the command
8242 line as a command to pass straight to exec, in the
8243 manner that <tt>xterm</tt> does.
8247 Support the command-line option <tt>-T
8248 <var>title</var></tt>, which creates a new terminal
8249 window with the window title <var>title</var>.
8256 <heading>Packages providing a window manager</heading>
8259 Packages that provide a window manager should declare in
8260 their control data that they provide the virtual package
8261 <tt>x-window-manager</tt>. They should also register
8262 themselves as an alternative for
8263 <file>/usr/bin/x-window-manager</file>, with a priority
8264 calculated as follows:
8265 <list compact="compact">
8267 Start with a priority of 20.
8271 If the window manager supports the Debian menu
8272 system, add 20 points if this support is available
8273 in the package's default configuration (i.e., no
8274 configuration files belonging to the system or user
8275 have to be edited to activate the feature); if
8276 configuration files must be modified, add only 10
8282 If the window manager complies with <url
8283 id="http://www.freedesktop.org/Standards/wm-spec"
8284 name="The Window Manager Specification Project">,
8285 written by the <url id="http://www.freedesktop.org/"
8286 name="Free Desktop Group">, add 40 points.
8290 If the window manager permits the X session to be
8291 restarted using a <em>different</em> window manager
8292 (without killing the X server) in its default
8293 configuration, add 10 points; otherwise add none.
8300 <heading>Packages providing fonts</heading>
8303 Packages that provide fonts for the X Window
8305 For the purposes of Debian Policy, a "font for the X
8306 Window System" is one which is accessed via X protocol
8307 requests. Fonts for the Linux console, for PostScript
8308 renderer, or any other purpose, do not fit this
8309 definition. Any tool which makes such fonts available
8310 to the X Window System, however, must abide by this
8313 must do a number of things to ensure that they are both
8314 available without modification of the X or font server
8315 configuration, and that they do not corrupt files used by
8316 other font packages to register information about
8320 Fonts of any type supported by the X Window System
8321 must be in a separate binary package from any
8322 executables, libraries, or documentation (except
8323 that specific to the fonts shipped, such as their
8324 license information). If one or more of the fonts
8325 so packaged are necessary for proper operation of
8326 the package with which they are associated the font
8327 package may be Recommended; if the fonts merely
8328 provide an enhancement, a Suggests relationship may
8329 be used. Packages must not Depend on font
8331 This is because the X server may retrieve fonts
8332 from the local file system or over the network
8333 from an X font server; the Debian package system
8334 is empowered to deal only with the local
8340 BDF fonts must be converted to PCF fonts with the
8341 <prgn>bdftopcf</prgn> utility (available in the
8342 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8343 placed in a directory that corresponds to their
8345 <list compact="compact">
8347 100 dpi fonts must be placed in
8348 <file>/usr/share/fonts/X11/100dpi/</file>.
8352 75 dpi fonts must be placed in
8353 <file>/usr/share/fonts/X11/75dpi/</file>.
8357 Character-cell fonts, cursor fonts, and other
8358 low-resolution fonts must be placed in
8359 <file>/usr/share/fonts/X11/misc/</file>.
8365 Speedo fonts must be placed in
8366 <file>/usr/share/fonts/X11/Speedo/</file>.
8370 Type 1 fonts must be placed in
8371 <file>/usr/share/fonts/X11/Type1/</file>. If font
8372 metric files are available, they must be placed here
8377 Subdirectories of <file>/usr/share/fonts/X11/</file>
8378 other than those listed above must be neither
8379 created nor used. (The <file>PEX</file>, <file>CID</file>,
8380 and <file>cyrillic</file> directories are excepted for
8381 historical reasons, but installation of files into
8382 these directories remains discouraged.)
8386 Font packages may, instead of placing files directly
8387 in the X font directories listed above, provide
8388 symbolic links in that font directory pointing to
8389 the files' actual location in the filesystem. Such
8390 a location must comply with the FHS.
8394 Font packages should not contain both 75dpi and
8395 100dpi versions of a font. If both are available,
8396 they should be provided in separate binary packages
8397 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8398 the names of the packages containing the
8399 corresponding fonts.
8403 Fonts destined for the <file>misc</file> subdirectory
8404 should not be included in the same package as 75dpi
8405 or 100dpi fonts; instead, they should be provided in
8406 a separate package with <tt>-misc</tt> appended to
8411 Font packages must not provide the files
8412 <file>fonts.dir</file>, <file>fonts.alias</file>, or
8413 <file>fonts.scale</file> in a font directory:
8416 <file>fonts.dir</file> files must not be provided at all.
8420 <file>fonts.alias</file> and <file>fonts.scale</file>
8421 files, if needed, should be provided in the
8423 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
8424 where <var>fontdir</var> is the name of the
8426 <file>/usr/share/fonts/X11/</file> where the
8427 package's corresponding fonts are stored
8428 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
8429 <var>package</var> is the name of the package
8430 that provides these fonts, and
8431 <var>extension</var> is either <tt>scale</tt>
8432 or <tt>alias</tt>, whichever corresponds to
8439 Font packages must declare a dependency on
8440 <tt>xfonts-utils</tt> in their control
8445 Font packages that provide one or more
8446 <file>fonts.scale</file> files as described above must
8447 invoke <prgn>update-fonts-scale</prgn> on each
8448 directory into which they installed fonts
8449 <em>before</em> invoking
8450 <prgn>update-fonts-dir</prgn> on that directory.
8451 This invocation must occur in both the
8452 <prgn>postinst</prgn> (for all arguments) and
8453 <prgn>postrm</prgn> (for all arguments except
8454 <tt>upgrade</tt>) scripts.
8458 Font packages that provide one or more
8459 <file>fonts.alias</file> files as described above must
8460 invoke <prgn>update-fonts-alias</prgn> on each
8461 directory into which they installed fonts. This
8462 invocation must occur in both the
8463 <prgn>postinst</prgn> (for all arguments) and
8464 <prgn>postrm</prgn> (for all arguments except
8465 <tt>upgrade</tt>) scripts.
8469 Font packages must invoke
8470 <prgn>update-fonts-dir</prgn> on each directory into
8471 which they installed fonts. This invocation must
8472 occur in both the <prgn>postinst</prgn> (for all
8473 arguments) and <prgn>postrm</prgn> (for all
8474 arguments except <tt>upgrade</tt>) scripts.
8478 Font packages must not provide alias names for the
8479 fonts they include which collide with alias names
8480 already in use by fonts already packaged.
8484 Font packages must not provide fonts with the same
8485 XLFD registry name as another font already packaged.
8492 <heading>Application defaults files</heading>
8495 Application defaults files must be installed in the
8496 directory <file>/etc/X11/app-defaults/</file> (use of a
8497 localized subdirectory of <file>/etc/X11/</file> as described
8498 in the <em>X Toolkit Intrinsics - C Language
8499 Interface</em> manual is also permitted). They must be
8500 registered as <tt>conffile</tt>s or handled as
8501 configuration files.
8505 Customization of programs' X resources may also be
8506 supported with the provision of a file with the same name
8507 as that of the package placed in the
8508 <file>/etc/X11/Xresources/</file> directory, which must
8509 registered as a <tt>conffile</tt> or handled as a
8510 configuration file.<footnote>
8511 Note that this mechanism is not the same as using
8512 app-defaults; app-defaults are tied to the client
8513 binary on the local file system, whereas X resources
8514 are stored in the X server and affect all connecting
8521 <heading>Installation directory issues</heading>
8524 Packages using the X Window System should not be
8525 configured to install files under the
8526 <file>/usr/X11R6/</file> directory. The
8527 <file>/usr/X11R6/</file> directory hierarchy should be
8528 regarded as obsolete.
8532 Programs that use GNU <prgn>autoconf</prgn> and
8533 <prgn>automake</prgn> are usually easily configured at
8534 compile time to use <file>/usr/</file> instead of
8535 <file>/usr/X11R6/</file>, and this should be done whenever
8536 possible. Configuration files for window managers and
8537 display managers should be placed in a subdirectory of
8538 <file>/etc/X11/</file> corresponding to the package name due
8539 to these programs' tight integration with the mechanisms
8540 of the X Window System. Application-level programs should
8541 use the <file>/etc/</file> directory unless otherwise mandated
8546 The installation of files into subdirectories
8547 of <file>/usr/X11R6/include/X11/</file> and
8548 <file>/usr/X11R6/lib/X11/</file> is now prohibited;
8549 package maintainers should determine if subdirectories of
8550 <file>/usr/lib/</file> and <file>/usr/share/</file> can be used
8555 Packages should install any relevant files into the
8556 directories <file>/usr/include/X11/</file> and
8557 <file>/usr/lib/X11/</file>, but if they do so, they must
8558 pre-depend on <tt>x11-common (>=
8559 1:7.0.0)</tt><footnote>
8561 These libraries used to be all symbolic
8562 links. However, with <tt>X11R7</tt>,
8563 <tt>/usr/include/X11</tt> and <tt>/usr/lib/X11</tt>
8564 are now real directories, and packages
8565 <strong>should</strong> ship their files here instead
8566 of in <tt>/usr/X11R6/{include,lib}/X11</tt>.
8567 <tt>x11-common (>= 1:7.0.0) </tt> is the package
8568 responsible for converting these symlinks into
8576 <heading>The OSF/Motif and OpenMotif libraries</heading>
8579 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8580 OpenMotif libraries</em><footnote>
8581 OSF/Motif and OpenMotif are collectively referred to as
8582 "Motif" in this policy document.
8584 should be compiled against and tested with LessTif (a free
8585 re-implementation of Motif) instead. If the maintainer
8586 judges that the program or programs do not work
8587 sufficiently well with LessTif to be distributed and
8588 supported, but do so when compiled against Motif, then two
8589 versions of the package should be created; one linked
8590 statically against Motif and with <tt>-smotif</tt>
8591 appended to the package name, and one linked dynamically
8592 against Motif and with <tt>-dmotif</tt> appended to the
8597 Both Motif-linked versions are dependent
8598 upon non-DFSG-compliant software and thus cannot be
8599 uploaded to the <em>main</em> distribution; if the
8600 software is itself DFSG-compliant it may be uploaded to
8601 the <em>contrib</em> distribution. While known existing
8602 versions of Motif permit unlimited redistribution of
8603 binaries linked against the library (whether statically or
8604 dynamically), it is the package maintainer's
8605 responsibility to determine whether this is permitted by
8606 the license of the copy of Motif in their possession.
8612 <heading>Perl programs and modules</heading>
8615 Perl programs and modules should follow the current Perl policy.
8619 The Perl policy can be found in the <tt>perl-policy</tt>
8620 files in the <tt>debian-policy</tt> package.
8621 It is also available from the Debian web mirrors at
8622 <tt><url name="/doc/packaging-manuals/perl-policy/"
8623 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8628 <heading>Emacs lisp programs</heading>
8631 Please refer to the "Debian Emacs Policy" for details of how to
8632 package emacs lisp programs.
8636 The Emacs policy is available in
8637 <file>debian-emacs-policy.gz</file> of the
8638 <package>emacsen-common</package> package.
8639 It is also available from the Debian web mirrors at
8640 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8641 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8646 <heading>Games</heading>
8649 The permissions on <file>/var/games</file> are mode 755, owner
8650 <tt>root</tt> and group <tt>root</tt>.
8654 Each game decides on its own security policy.</p>
8657 Games which require protected, privileged access to
8658 high-score files, saved games, etc., may be made
8659 set-<em>group</em>-id (mode 2755) and owned by
8660 <tt>root:games</tt>, and use files and directories with
8661 appropriate permissions (770 <tt>root:games</tt>, for
8662 example). They must not be made
8663 set-<em>user</em>-id, as this causes security problems. (If
8664 an attacker can subvert any set-user-id game they can
8665 overwrite the executable of any other, causing other players
8666 of these games to run a Trojan horse program. With a
8667 set-group-id game the attacker only gets access to less
8668 important game data, and if they can get at the other
8669 players' accounts at all it will take considerably more
8673 Some packages, for example some fortune cookie programs, are
8674 configured by the upstream authors to install with their
8675 data files or other static information made unreadable so
8676 that they can only be accessed through set-id programs
8677 provided. You should not do this in a Debian package: anyone can
8678 download the <file>.deb</file> file and read the data from it,
8679 so there is no point making the files unreadable. Not
8680 making the files unreadable also means that you don't have
8681 to make so many programs set-id, which reduces the risk of a
8685 As described in the FHS, binaries of games should be
8686 installed in the directory <file>/usr/games</file>. This also
8687 applies to games that use the X Window System. Manual pages
8688 for games (X and non-X games) should be installed in
8689 <file>/usr/share/man/man6</file>.</p>
8695 <heading>Documentation</heading>
8698 <heading>Manual pages</heading>
8701 You should install manual pages in <prgn>nroff</prgn> source
8702 form, in appropriate places under <file>/usr/share/man</file>.
8703 You should only use sections 1 to 9 (see the FHS for more
8704 details). You must not install a pre-formatted "cat page".
8708 Each program, utility, and function should have an
8709 associated manual page included in the same package. It is
8710 suggested that all configuration files also have a manual
8711 page included as well. Manual pages for protocols and other
8712 auxiliary things are optional.
8716 If no manual page is available, this is considered as a bug
8717 and should be reported to the Debian Bug Tracking System (the
8718 maintainer of the package is allowed to write this bug report
8719 themselves, if they so desire). Do not close the bug report
8720 until a proper man page is available.<footnote>
8721 It is not very hard to write a man page. See the
8722 <url id="http://www.schweikhardt.net/man_page_howto.html"
8723 name="Man-Page-HOWTO">,
8724 <manref name="man" section="7">, the examples
8725 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8726 the helper programs <prgn>help2man</prgn>, or the
8727 directory <file>/usr/share/doc/man-db/examples</file>.
8732 You may forward a complaint about a missing man page to the
8733 upstream authors, and mark the bug as forwarded in the
8734 Debian bug tracking system. Even though the GNU Project do
8735 not in general consider the lack of a man page to be a bug,
8736 we do; if they tell you that they don't consider it a bug
8737 you should leave the bug in our bug tracking system open
8742 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8746 If one man page needs to be accessible via several names it
8747 is better to use a symbolic link than the <file>.so</file>
8748 feature, but there is no need to fiddle with the relevant
8749 parts of the upstream source to change from <file>.so</file> to
8750 symlinks: don't do it unless it's easy. You should not
8751 create hard links in the manual page directories, nor put
8752 absolute filenames in <file>.so</file> directives. The filename
8753 in a <file>.so</file> in a man page should be relative to the
8754 base of the man page tree (usually
8755 <file>/usr/share/man</file>). If you do not create any links
8756 (whether symlinks, hard links, or <tt>.so</tt> directives)
8757 in the file system to the alternate names of the man page,
8758 then you should not rely on <prgn>man</prgn> finding your
8759 man page under those names based solely on the information in
8760 the man page's header.<footnote>
8761 Supporting this in <prgn>man</prgn> often requires
8762 unreasonable processing time to find a manual page or to
8763 report that none exists, and moves knowledge into man's
8764 database that would be better left in the file system.
8765 This support is therefore deprecated and will cease to
8766 be present in the future.
8771 Manual pages in locale-specific subdirectories of
8772 <file>/usr/share/man</file> should use either UTF-8 or the usual
8773 legacy encoding for that language (normally the one corresponding
8774 to the shortest relevant locale name in
8775 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
8776 <file>/usr/share/man/fr</file> should use either UTF-8 or
8777 ISO-8859-1.<footnote>
8778 <prgn>man</prgn> will automatically detect whether UTF-8 is in
8779 use. In future, all manual pages will be required to use
8785 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
8786 included in the subdirectory name unless it indicates a
8787 significant difference in the language, as this excludes
8788 speakers of the language in other countries.<footnote>
8789 At the time of writing, Chinese and Portuguese are the main
8790 languages with such differences, so <file>pt_BR</file>,
8791 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
8796 Due to limitations in current implementations, all characters
8797 in the manual page source should be representable in the usual
8798 legacy encoding for that language, even if the file is
8799 actually encoded in UTF-8. Safe alternative ways to write many
8800 characters outside that range may be found in
8801 <manref name="groff_char" section="7">.
8806 <heading>Info documents</heading>
8809 Info documents should be installed in <file>/usr/share/info</file>.
8810 They should be compressed with <tt>gzip -9</tt>.
8814 Your package should call <prgn>install-info</prgn> to update
8815 the Info <file>dir</file> file in its <prgn>postinst</prgn>
8816 script when called with a <tt>configure</tt> argument, for
8818 <example compact="compact">
8819 install-info --quiet --section Development Development \
8820 /usr/share/info/foobar.info
8824 It is a good idea to specify a section for the location of
8825 your program; this is done with the <tt>--section</tt>
8826 switch. To determine which section to use, you should look
8827 at <file>/usr/share/info/dir</file> on your system and choose the most
8828 relevant (or create a new section if none of the current
8829 sections are relevant). Note that the <tt>--section</tt>
8830 flag takes two arguments; the first is a regular expression
8831 to match (case-insensitively) against an existing section,
8832 the second is used when creating a new one.</p>
8835 You should remove the entries in the <prgn>prerm</prgn>
8836 script when called with a <tt>remove</tt> argument:
8837 <example compact="compact">
8838 install-info --quiet --remove /usr/share/info/foobar.info
8842 If <prgn>install-info</prgn> cannot find a description entry
8843 in the Info file you must supply one. See <manref
8844 name="install-info" section="8"> for details.</p>
8848 <heading>Additional documentation</heading>
8851 Any additional documentation that comes with the package may
8852 be installed at the discretion of the package maintainer.
8853 Plain text documentation should be installed in the directory
8854 <file>/usr/share/doc/<var>package</var></file>, where
8855 <var>package</var> is the name of the package, and
8856 compressed with <tt>gzip -9</tt> unless it is small.
8860 If a package comes with large amounts of documentation which
8861 many users of the package will not require you should create
8862 a separate binary package to contain it, so that it does not
8863 take up disk space on the machines of users who do not need
8864 or want it installed.</p>
8867 It is often a good idea to put text information files
8868 (<file>README</file>s, changelogs, and so forth) that come with
8869 the source package in <file>/usr/share/doc/<var>package</var></file>
8870 in the binary package. However, you don't need to install
8871 the instructions for building and installing the package, of
8875 Packages must not require the existence of any files in
8876 <file>/usr/share/doc/</file> in order to function
8878 The system administrator should be able to
8879 delete files in <file>/usr/share/doc/</file> without causing
8880 any programs to break.
8882 Any files that are referenced by programs but are also
8883 useful as stand alone documentation should be installed under
8884 <file>/usr/share/<var>package</var>/</file> with symbolic links from
8885 <file>/usr/share/doc/<var>package</var></file>.
8889 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8890 link to another directory in <file>/usr/share/doc</file> only if
8891 the two packages both come from the same source and the
8892 first package Depends on the second.<footnote>
8894 Please note that this does not override the section on
8895 changelog files below, so the file
8896 <file>/usr/share/<var>package</var>/changelog.Debian.gz</file>
8897 must refer to the changelog for the current version of
8898 <var>package</var> in question. In practice, this means
8899 that the sources of the target and the destination of the
8900 symlink must be the same (same source package and
8907 Former Debian releases placed all additional documentation
8908 in <file>/usr/doc/<var>package</var></file>. This has been
8909 changed to <file>/usr/share/doc/<var>package</var></file>,
8910 and packages must not put documentation in the directory
8911 <file>/usr/doc/<var>package</var></file>. <footnote>
8912 At this phase of the transition, we no longer require a
8913 symbolic link in <file>/usr/doc/</file>. At a later point,
8914 policy shall change to make the symbolic links a bug.
8920 <heading>Preferred documentation formats</heading>
8923 The unification of Debian documentation is being carried out
8927 If your package comes with extensive documentation in a
8928 markup format that can be converted to various other formats
8929 you should if possible ship HTML versions in a binary
8930 package, in the directory
8931 <file>/usr/share/doc/<var>appropriate-package</var></file> or
8932 its subdirectories.<footnote>
8933 The rationale: The important thing here is that HTML
8934 docs should be available in <em>some</em> package, not
8935 necessarily in the main binary package.
8940 Other formats such as PostScript may be provided at the
8941 package maintainer's discretion.
8945 <sect id="copyrightfile">
8946 <heading>Copyright information</heading>
8949 Every package must be accompanied by a verbatim copy of its
8950 copyright and distribution license in the file
8951 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
8952 file must neither be compressed nor be a symbolic link.
8956 In addition, the copyright file must say where the upstream
8957 sources (if any) were obtained. It should name the original
8958 authors of the package and the Debian maintainer(s) who were
8959 involved with its creation.
8963 Packages in the <em>contrib</em> or <em>non-free</em> categories
8964 should state in the copyright file that the package is not part
8965 of the Debian GNU/Linux distribution and briefly explain why.
8969 A copy of the file which will be installed in
8970 <file>/usr/share/doc/<var>package</var>/copyright</file> should
8971 be in <file>debian/copyright</file> in the source package.
8975 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8976 link to another directory in <file>/usr/share/doc</file> only if
8977 the two packages both come from the same source and the
8978 first package Depends on the second. These rules are
8979 important because copyrights must be extractable by
8984 Packages distributed under the UCB BSD license, the Apache
8985 license (version 2.0), the Artistic license, the GNU GPL
8986 (version 2 or 3), the GNU LGPL (versions 2, 2.1, or 3), and
8987 the GNU FDL (version 1.2) should refer to the corresponding
8988 files under <file>/usr/share/common-licenses</file>,<footnote>
8991 <file>/usr/share/common-licenses/BSD</file>,
8992 <file>/usr/share/common-licenses/Apache-2.0</file>,
8993 <file>/usr/share/common-licenses/Artistic</file>,
8994 <file>/usr/share/common-licenses/GPL-2</file>,
8995 <file>/usr/share/common-licenses/GPL-3</file>,
8996 <file>/usr/share/common-licenses/LGPL-2</file>,
8997 <file>/usr/share/common-licenses/LGPL-2.1</file>,
8998 <file>/usr/share/common-licenses/LGPL-3</file>, and
8999 <file>/usr/share/common-licenses/GFDL-1.2</file>
9002 </footnote> rather than quoting them in the copyright
9007 You should not use the copyright file as a general <file>README</file>
9008 file. If your package has such a file it should be
9009 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9010 <file>README.Debian</file> or some other appropriate place.</p>
9014 <heading>Examples</heading>
9017 Any examples (configurations, source files, whatever),
9018 should be installed in a directory
9019 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9020 files should not be referenced by any program: they're there
9021 for the benefit of the system administrator and users as
9022 documentation only. Architecture-specific example files
9023 should be installed in a directory
9024 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9026 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9027 latter directory itself may be a symbolic link to the
9032 If the purpose of a package is to provide examples, then the
9033 example files may be installed into
9034 <file>/usr/share/doc/<var>package</var></file>.
9038 <sect id="changelogs">
9039 <heading>Changelog files</heading>
9042 Packages that are not Debian-native must contain a
9043 compressed copy of the <file>debian/changelog</file> file from
9044 the Debian source tree in
9045 <file>/usr/share/doc/<var>package</var></file> with the name
9046 <file>changelog.Debian.gz</file>.
9050 If an upstream changelog is available, it should be accessible as
9051 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9052 plain text. If the upstream changelog is distributed in
9053 HTML, it should be made available in that form as
9054 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9055 and a plain text <file>changelog.gz</file> should be generated
9056 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9057 the upstream changelog files do not already conform to this
9058 naming convention, then this may be achieved either by
9059 renaming the files, or by adding a symbolic link, at the
9060 maintainer's discretion.<footnote>
9061 Rationale: People should not have to look in places for
9062 upstream changelogs merely because they are given
9063 different names or are distributed in HTML format.
9068 All of these files should be installed compressed using
9069 <tt>gzip -9</tt>, as they will become large with time even
9070 if they start out small.
9074 If the package has only one changelog which is used both as
9075 the Debian changelog and the upstream one because there is
9076 no separate upstream maintainer then that changelog should
9077 usually be installed as
9078 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9079 there is a separate upstream maintainer, but no upstream
9080 changelog, then the Debian changelog should still be called
9081 <file>changelog.Debian.gz</file>.
9085 For details about the format and contents of the Debian
9086 changelog file, please see <ref id="dpkgchangelog">.
9091 <appendix id="pkg-scope">
9092 <heading>Introduction and scope of these appendices</heading>
9095 These appendices are taken essentially verbatim from the
9096 now-deprecated Packaging Manual, version 3.2.1.0. They are
9097 the chapters which are likely to be of use to package
9098 maintainers and which have not already been included in the
9099 policy document itself. Most of these sections are very likely
9100 not relevant to policy; they should be treated as
9101 documentation for the packaging system. Please note that these
9102 appendices are included for convenience, and for historical
9103 reasons: they used to be part of policy package, and they have
9104 not yet been incorporated into dpkg documentation. However,
9105 they still have value, and hence they are presented here.
9109 They have not yet been checked to ensure that they are
9110 compatible with the contents of policy, and if there are any
9111 contradictions, the version in the main policy document takes
9112 precedence. The remaining chapters of the old Packaging
9113 Manual have also not been read in detail to ensure that there
9114 are not parts which have been left out. Both of these will be
9119 Certain parts of the Packaging manual were integrated into the
9120 Policy Manual proper, and removed from the appendices. Links
9121 have been placed from the old locations to the new ones.
9125 <prgn>dpkg</prgn> is a suite of programs for creating binary
9126 package files and installing and removing them on Unix
9128 <prgn>dpkg</prgn> is targeted primarily at Debian
9129 GNU/Linux, but may work on or be ported to other
9135 The binary packages are designed for the management of
9136 installed executable programs (usually compiled binaries) and
9137 their associated data, though source code examples and
9138 documentation are provided as part of some packages.</p>
9141 This manual describes the technical aspects of creating Debian
9142 binary packages (<file>.deb</file> files). It documents the
9143 behavior of the package management programs
9144 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9145 they interact with packages.</p>
9148 It also documents the interaction between
9149 <prgn>dselect</prgn>'s core and the access method scripts it
9150 uses to actually install the selected packages, and describes
9151 how to create a new access method.</p>
9154 This manual does not go into detail about the options and
9155 usage of the package building and installation tools. It
9156 should therefore be read in conjunction with those programs'
9161 The utility programs which are provided with <prgn>dpkg</prgn>
9162 for managing various system configuration and similar issues,
9163 such as <prgn>update-rc.d</prgn> and
9164 <prgn>install-info</prgn>, are not described in detail here -
9165 please see their man pages.
9169 It is assumed that the reader is reasonably familiar with the
9170 <prgn>dpkg</prgn> System Administrators' manual.
9171 Unfortunately this manual does not yet exist.
9175 The Debian version of the FSF's GNU hello program is provided
9176 as an example for people wishing to create Debian
9177 packages. The Debian <prgn>debmake</prgn> package is
9178 recommended as a very helpful tool in creating and maintaining
9179 Debian packages. However, while the tools and examples are
9180 helpful, they do not replace the need to read and follow the
9181 Policy and Programmer's Manual.</p>
9184 <appendix id="pkg-binarypkg">
9185 <heading>Binary packages (from old Packaging Manual)</heading>
9188 The binary package has two main sections. The first part
9189 consists of various control information files and scripts used
9190 by <prgn>dpkg</prgn> when installing and removing. See <ref
9191 id="pkg-controlarea">.
9195 The second part is an archive containing the files and
9196 directories to be installed.
9200 In the future binary packages may also contain other
9201 components, such as checksums and digital signatures. The
9202 format for the archive is described in full in the
9203 <file>deb(5)</file> man page.
9207 <sect id="pkg-bincreating"><heading>Creating package files -
9208 <prgn>dpkg-deb</prgn>
9212 All manipulation of binary package files is done by
9213 <prgn>dpkg-deb</prgn>; it's the only program that has
9214 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9215 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9216 will spot that the options requested are appropriate to
9217 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9222 In order to create a binary package you must make a
9223 directory tree which contains all the files and directories
9224 you want to have in the file system data part of the package.
9225 In Debian-format source packages this directory is usually
9226 <file>debian/tmp</file>, relative to the top of the package's
9231 They should have the locations (relative to the root of the
9232 directory tree you're constructing) ownerships and
9233 permissions which you want them to have on the system when
9238 With current versions of <prgn>dpkg</prgn> the uid/username
9239 and gid/groupname mappings for the users and groups being
9240 used should be the same on the system where the package is
9241 built and the one where it is installed.
9245 You need to add one special directory to the root of the
9246 miniature file system tree you're creating:
9247 <prgn>DEBIAN</prgn>. It should contain the control
9248 information files, notably the binary package control file
9249 (see <ref id="pkg-controlfile">).
9253 The <prgn>DEBIAN</prgn> directory will not appear in the
9254 file system archive of the package, and so won't be installed
9255 by <prgn>dpkg</prgn> when the package is installed.
9259 When you've prepared the package, you should invoke:
9261 dpkg --build <var>directory</var>
9266 This will build the package in
9267 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9268 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9269 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9274 See the man page <manref name="dpkg-deb" section="8"> for details of how
9275 to examine the contents of this newly-created file. You may find the
9276 output of following commands enlightening:
9278 dpkg-deb --info <var>filename</var>.deb
9279 dpkg-deb --contents <var>filename</var>.deb
9280 dpkg --contents <var>filename</var>.deb
9282 To view the copyright file for a package you could use this command:
9284 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - \*/copyright | pager
9289 <sect id="pkg-controlarea">
9290 <heading>Package control information files</heading>
9293 The control information portion of a binary package is a
9294 collection of files with names known to <prgn>dpkg</prgn>.
9295 It will treat the contents of these files specially - some
9296 of them contain information used by <prgn>dpkg</prgn> when
9297 installing or removing the package; others are scripts which
9298 the package maintainer wants <prgn>dpkg</prgn> to run.
9302 It is possible to put other files in the package control
9303 area, but this is not generally a good idea (though they
9304 will largely be ignored).
9308 Here is a brief list of the control info files supported by
9309 <prgn>dpkg</prgn> and a summary of what they're used for.
9314 <tag><tt>control</tt>
9317 This is the key description file used by
9318 <prgn>dpkg</prgn>. It specifies the package's name
9319 and version, gives its description for the user,
9320 states its relationships with other packages, and so
9321 forth. See <ref id="sourcecontrolfiles"> and
9322 <ref id="binarycontrolfiles">.
9326 It is usually generated automatically from information
9327 in the source package by the
9328 <prgn>dpkg-gencontrol</prgn> program, and with
9329 assistance from <prgn>dpkg-shlibdeps</prgn>.
9330 See <ref id="pkg-sourcetools">.
9334 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9339 These are executable files (usually scripts) which
9340 <prgn>dpkg</prgn> runs during installation, upgrade
9341 and removal of packages. They allow the package to
9342 deal with matters which are particular to that package
9343 or require more complicated processing than that
9344 provided by <prgn>dpkg</prgn>. Details of when and
9345 how they are called are in <ref id="maintainerscripts">.
9349 It is very important to make these scripts idempotent.
9350 See <ref id="idempotency">.
9354 The maintainer scripts are guaranteed to run with a
9355 controlling terminal and can interact with the user.
9356 See <ref id="controllingterminal">.
9360 <tag><tt>conffiles</tt>
9363 This file contains a list of configuration files which
9364 are to be handled automatically by <prgn>dpkg</prgn>
9365 (see <ref id="pkg-conffiles">). Note that not necessarily
9366 every configuration file should be listed here.
9369 <tag><tt>shlibs</tt>
9372 This file contains a list of the shared libraries
9373 supplied by the package, with dependency details for
9374 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9375 when it determines what dependencies are required in a
9376 package control file. The <tt>shlibs</tt> file format
9377 is described on <ref id="shlibs">.
9382 <sect id="pkg-controlfile">
9383 <heading>The main control information file: <tt>control</tt></heading>
9386 The most important control information file used by
9387 <prgn>dpkg</prgn> when it installs a package is
9388 <tt>control</tt>. It contains all the package's "vital
9393 The binary package control files of packages built from
9394 Debian sources are made by a special tool,
9395 <prgn>dpkg-gencontrol</prgn>, which reads
9396 <file>debian/control</file> and <file>debian/changelog</file> to
9397 find the information it needs. See <ref id="pkg-sourcepkg"> for
9402 The fields in binary package control files are listed in
9403 <ref id="binarycontrolfiles">.
9407 A description of the syntax of control files and the purpose
9408 of the fields is available in <ref id="controlfields">.
9413 <heading>Time Stamps</heading>
9416 See <ref id="timestamps">.
9421 <appendix id="pkg-sourcepkg">
9422 <heading>Source packages (from old Packaging Manual) </heading>
9425 The Debian binary packages in the distribution are generated
9426 from Debian sources, which are in a special format to assist
9427 the easy and automatic building of binaries.
9430 <sect id="pkg-sourcetools">
9431 <heading>Tools for processing source packages</heading>
9434 Various tools are provided for manipulating source packages;
9435 they pack and unpack sources and help build of binary
9436 packages and help manage the distribution of new versions.
9440 They are introduced and typical uses described here; see
9441 <manref name="dpkg-source" section="1"> for full
9442 documentation about their arguments and operation.
9446 For examples of how to construct a Debian source package,
9447 and how to use those utilities that are used by Debian
9448 source packages, please see the <prgn>hello</prgn> example
9452 <sect1 id="pkg-dpkg-source">
9454 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
9459 This program is frequently used by hand, and is also
9460 called from package-independent automated building scripts
9461 such as <prgn>dpkg-buildpackage</prgn>.
9465 To unpack a package it is typically invoked with
9467 dpkg-source -x <var>.../path/to/filename</var>.dsc
9472 with the <file><var>filename</var>.tar.gz</file> and
9473 <file><var>filename</var>.diff.gz</file> (if applicable) in
9474 the same directory. It unpacks into
9475 <file><var>package</var>-<var>version</var></file>, and if
9477 <file><var>package</var>-<var>version</var>.orig</file>, in
9478 the current directory.
9482 To create a packed source archive it is typically invoked:
9484 dpkg-source -b <var>package</var>-<var>version</var>
9489 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
9490 <file>.diff.gz</file> (if appropriate) in the current
9491 directory. <prgn>dpkg-source</prgn> does not clean the
9492 source tree first - this must be done separately if it is
9497 See also <ref id="pkg-sourcearchives">.</p>
9501 <sect1 id="pkg-dpkg-buildpackage">
9503 <prgn>dpkg-buildpackage</prgn> - overall package-building
9508 <prgn>dpkg-buildpackage</prgn> is a script which invokes
9509 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
9510 targets <tt>clean</tt>, <tt>build</tt> and
9511 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
9512 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
9513 source and binary package upload.
9517 It is usually invoked by hand from the top level of the
9518 built or unbuilt source directory. It may be invoked with
9519 no arguments; useful arguments include:
9520 <taglist compact="compact">
9521 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
9524 Do not sign the <tt>.changes</tt> file or the
9525 source package <tt>.dsc</tt> file, respectively.</p>
9527 <tag><tt>-p<var>sign-command</var></tt></tag>
9530 Invoke <var>sign-command</var> instead of finding
9531 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
9532 <var>sign-command</var> must behave just like
9533 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9535 <tag><tt>-r<var>root-command</var></tt></tag>
9538 When root privilege is required, invoke the command
9539 <var>root-command</var>. <var>root-command</var>
9540 should invoke its first argument as a command, from
9541 the <prgn>PATH</prgn> if necessary, and pass its
9542 second and subsequent arguments to the command it
9543 calls. If no <var>root-command</var> is supplied
9544 then <var>dpkg-buildpackage</var> will take no
9545 special action to gain root privilege, so that for
9546 most packages it will have to be invoked as root to
9549 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9552 Two types of binary-only build and upload - see
9553 <manref name="dpkg-source" section="1">.
9560 <sect1 id="pkg-dpkg-gencontrol">
9562 <prgn>dpkg-gencontrol</prgn> - generates binary package
9567 This program is usually called from <file>debian/rules</file>
9568 (see <ref id="pkg-sourcetree">) in the top level of the source
9573 This is usually done just before the files and directories in the
9574 temporary directory tree where the package is being built have their
9575 permissions and ownerships set and the package is constructed using
9576 <prgn>dpkg-deb/</prgn>
9578 This is so that the control file which is produced has
9579 the right permissions
9584 <prgn>dpkg-gencontrol</prgn> must be called after all the
9585 files which are to go into the package have been placed in
9586 the temporary build directory, so that its calculation of
9587 the installed size of a package is correct.
9591 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9592 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9593 variable substitutions created by
9594 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9599 For a package which generates only one binary package, and
9600 which builds it in <file>debian/tmp</file> relative to the top
9601 of the source package, it is usually sufficient to call
9602 <prgn>dpkg-gencontrol</prgn>.
9606 Sources which build several binaries will typically need
9609 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9610 </example> The <tt>-P</tt> tells
9611 <prgn>dpkg-gencontrol</prgn> that the package is being
9612 built in a non-default directory, and the <tt>-p</tt>
9613 tells it which package's control file should be generated.
9617 <prgn>dpkg-gencontrol</prgn> also adds information to the
9618 list of files in <file>debian/files</file>, for the benefit of
9619 (for example) a future invocation of
9620 <prgn>dpkg-genchanges</prgn>.</p>
9623 <sect1 id="pkg-dpkg-shlibdeps">
9625 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9630 This program is usually called from <file>debian/rules</file>
9631 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9632 id="pkg-sourcetree">), in the top level of the source tree.
9636 Its arguments are executables and shared libraries
9639 They may be specified either in the locations in the
9640 source tree where they are created or in the locations
9641 in the temporary build tree where they are installed
9642 prior to binary package creation.
9644 </footnote> for which shared library dependencies should
9645 be included in the binary package's control file.
9649 If some of the found shared libraries should only
9650 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9651 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9652 by using the <tt>-d<var>dependency-field</var></tt> option
9653 before those executable(s). (Each <tt>-d</tt> option
9654 takes effect until the next <tt>-d</tt>.)
9658 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9659 output control file to be modified. Instead by default it
9660 adds to the <file>debian/substvars</file> file variable
9661 settings like <tt>shlibs:Depends</tt>. These variable
9662 settings must be referenced in dependency fields in the
9663 appropriate per-binary-package sections of the source
9668 For example, a package that generates an essential part
9669 which requires dependencies, and optional parts that
9670 which only require a recommendation, would separate those
9671 two sets of dependencies into two different fields.<footnote>
9672 At the time of writing, an example for this was the
9673 <package/xmms/ package, with Depends used for the xmms
9674 executable, Recommends for the plug-ins and Suggests for
9675 even more optional features provided by unzip.
9677 It can say in its <file>debian/rules</file>:
9679 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9680 -dRecommends <var>optionalpart anotheroptionalpart</var>
9682 and then in its main control file <file>debian/control</file>:
9685 Depends: ${shlibs:Depends}
9686 Recommends: ${shlibs:Recommends}
9692 Sources which produce several binary packages with
9693 different shared library dependency requirements can use
9694 the <tt>-p<var>varnameprefix</var></tt> option to override
9695 the default <tt>shlibs:</tt> prefix (one invocation of
9696 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9697 They can thus produce several sets of dependency
9698 variables, each of the form
9699 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9700 which can be referred to in the appropriate parts of the
9701 binary package control files.
9706 <sect1 id="pkg-dpkg-distaddfile">
9708 <prgn>dpkg-distaddfile</prgn> - adds a file to
9709 <file>debian/files</file>
9713 Some packages' uploads need to include files other than
9714 the source and binary package files.
9718 <prgn>dpkg-distaddfile</prgn> adds a file to the
9719 <file>debian/files</file> file so that it will be included in
9720 the <file>.changes</file> file when
9721 <prgn>dpkg-genchanges</prgn> is run.
9725 It is usually invoked from the <tt>binary</tt> target of
9726 <file>debian/rules</file>:
9728 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9730 The <var>filename</var> is relative to the directory where
9731 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9732 is usually the directory above the top level of the source
9733 tree. The <file>debian/rules</file> target should put the
9734 file there just before or just after calling
9735 <prgn>dpkg-distaddfile</prgn>.
9739 The <var>section</var> and <var>priority</var> are passed
9740 unchanged into the resulting <file>.changes</file> file.
9745 <sect1 id="pkg-dpkg-genchanges">
9747 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9752 This program is usually called by package-independent
9753 automatic building scripts such as
9754 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9759 It is usually called in the top level of a built source
9760 tree, and when invoked with no arguments will print out a
9761 straightforward <file>.changes</file> file based on the
9762 information in the source package's changelog and control
9763 file and the binary and source packages which should have
9769 <sect1 id="pkg-dpkg-parsechangelog">
9771 <prgn>dpkg-parsechangelog</prgn> - produces parsed
9772 representation of a changelog
9776 This program is used internally by
9777 <prgn>dpkg-source</prgn> et al. It may also occasionally
9778 be useful in <file>debian/rules</file> and elsewhere. It
9779 parses a changelog, <file>debian/changelog</file> by default,
9780 and prints a control-file format representation of the
9781 information in it to standard output.
9785 <sect1 id="pkg-dpkg-architecture">
9787 <prgn>dpkg-architecture</prgn> - information about the build and
9792 This program can be used manually, but is also invoked by
9793 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9794 environment or make variables which specify the build and host
9795 architecture for the package building process.
9800 <sect id="pkg-sourcetree">
9801 <heading>The Debianised source tree</heading>
9804 The source archive scheme described later is intended to
9805 allow a Debianised source tree with some associated control
9806 information to be reproduced and transported easily. The
9807 Debianised source tree is a version of the original program
9808 with certain files added for the benefit of the
9809 Debianisation process, and with any other changes required
9810 made to the rest of the source code and installation
9815 The extra files created for Debian are in the subdirectory
9816 <file>debian</file> of the top level of the Debianised source
9817 tree. They are described below.
9820 <sect1 id="pkg-debianrules">
9821 <heading><file>debian/rules</file> - the main building script</heading>
9824 See <ref id="debianrules">.
9829 <sect1 id="pkg-dpkgchangelog">
9830 <heading><file>debian/changelog</file></heading>
9833 See <ref id="dpkgchangelog">.
9837 It is recommended that the entire changelog be encoded in the
9838 <url id="http://www.cis.ohio-state.edu/cgi-bin/rfc/rfc2279.html" name="UTF-8">
9840 <url id="http://www.unicode.org/"
9841 name="Unicode">.<footnote>
9843 I think it is fairly obvious that we need to
9844 eventually transition to UTF-8 for our package
9845 infrastructure; it is really the only sane char-set in
9846 an international environment. Now, we can't switch to
9847 using UTF-8 for package control fields and the like
9848 until dpkg has better support, but one thing we can
9849 start doing today is requesting that Debian changelogs
9850 are UTF-8 encoded. At some point in time, we can start
9851 requiring them to do so.
9854 Checking for non-UTF8 characters in a changelog is
9855 trivial. Dump the file through
9856 <example>iconv -f utf-8 -t ucs-4</example>
9857 discard the output, and check the return
9858 value. If there are any characters in the stream
9859 which are invalid UTF-8 sequences, iconv will exit
9860 with an error code; and this will be the case for the
9861 vast majority of other character sets.
9866 <sect2><heading>Defining alternative changelog formats
9870 It is possible to use a different format to the standard
9871 one, by providing a parser for the format you wish to
9876 In order to have <tt>dpkg-parsechangelog</tt> run your
9877 parser, you must include a line within the last 40 lines
9878 of your file matching the Perl regular expression:
9879 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9880 parentheses should be the name of the format. For
9881 example, you might say:
9883 @@@ changelog-format: joebloggs @@@
9885 Changelog format names are non-empty strings of alphanumerics.
9889 If such a line exists then <tt>dpkg-parsechangelog</tt>
9890 will look for the parser as
9891 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9893 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9894 it is an error for it not to find it, or for it not to
9895 be an executable program. The default changelog format
9896 is <tt>dpkg</tt>, and a parser for it is provided with
9897 the <tt>dpkg</tt> package.
9901 The parser will be invoked with the changelog open on
9902 standard input at the start of the file. It should read
9903 the file (it may seek if it wishes) to determine the
9904 information required and return the parsed information
9905 to standard output in the form of a series of control
9906 fields in the standard format. By default it should
9907 return information about only the most recent version in
9908 the changelog; it should accept a
9909 <tt>-v<var>version</var></tt> option to return changes
9910 information from all versions present <em>strictly
9911 after</em> <var>version</var>, and it should then be an
9912 error for <var>version</var> not to be present in the
9918 <list compact="compact">
9919 <item><qref id="f-Source"><tt>Source</tt></qref></item>
9920 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
9921 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
9922 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
9923 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
9924 <item><qref id="f-Date"><tt>Date</tt></qref></item>
9925 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
9930 If several versions are being returned (due to the use
9931 of <tt>-v</tt>), the urgency value should be of the
9932 highest urgency code listed at the start of any of the
9933 versions requested followed by the concatenated
9934 (space-separated) comments from all the versions
9935 requested; the maintainer, version, distribution and
9936 date should always be from the most recent version.
9940 For the format of the <tt>Changes</tt> field see
9941 <ref id="f-Changes">.
9945 If the changelog format which is being parsed always or
9946 almost always leaves a blank line between individual
9947 change notes these blank lines should be stripped out,
9948 so as to make the resulting output compact.
9952 If the changelog format does not contain date or package
9953 name information this information should be omitted from
9954 the output. The parser should not attempt to synthesize
9955 it or find it from other sources.
9959 If the changelog does not have the expected format the
9960 parser should exit with a nonzero exit status, rather
9961 than trying to muddle through and possibly generating
9966 A changelog parser may not interact with the user at
9972 <sect1 id="pkg-srcsubstvars">
9973 <heading><file>debian/substvars</file> and variable substitutions</heading>
9976 See <ref id="substvars">.
9982 <heading><file>debian/files</file></heading>
9985 See <ref id="debianfiles">.
9989 <sect1><heading><file>debian/tmp</file>
9993 This is the canonical temporary location for the
9994 construction of binary packages by the <tt>binary</tt>
9995 target. The directory <file>tmp</file> serves as the root of
9996 the file system tree as it is being constructed (for
9997 example, by using the package's upstream makefiles install
9998 targets and redirecting the output there), and it also
9999 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10000 id="pkg-bincreating">.
10004 If several binary packages are generated from the same
10005 source tree it is usual to use several
10006 <file>debian/tmp<var>something</var></file> directories, for
10007 example <file>tmp-a</file> or <file>tmp-doc</file>.
10011 Whatever <file>tmp</file> directories are created and used by
10012 <tt>binary</tt> must of course be removed by the
10013 <tt>clean</tt> target.</p></sect1>
10017 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10021 As it exists on the FTP site, a Debian source package
10022 consists of three related files. You must have the right
10023 versions of all three to be able to use them.
10028 <tag>Debian source control file - <tt>.dsc</tt></tag>
10030 This file is a control file used by <prgn>dpkg-source</prgn>
10031 to extract a source package.
10032 See <ref id="debiansourcecontrolfiles">.
10036 Original source archive -
10038 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10044 This is a compressed (with <tt>gzip -9</tt>)
10045 <prgn>tar</prgn> file containing the source code from
10046 the upstream authors of the program.
10051 Debianisation diff -
10053 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10059 This is a unified context diff (<tt>diff -u</tt>)
10060 giving the changes which are required to turn the
10061 original source into the Debian source. These changes
10062 may only include editing and creating plain files.
10063 The permissions of files, the targets of symbolic
10064 links and the characteristics of special files or
10065 pipes may not be changed and no files may be removed
10070 All the directories in the diff must exist, except the
10071 <file>debian</file> subdirectory of the top of the source
10072 tree, which will be created by
10073 <prgn>dpkg-source</prgn> if necessary when unpacking.
10077 The <prgn>dpkg-source</prgn> program will
10078 automatically make the <file>debian/rules</file> file
10079 executable (see below).</p></item>
10084 If there is no original source code - for example, if the
10085 package is specially prepared for Debian or the Debian
10086 maintainer is the same as the upstream maintainer - the
10087 format is slightly different: then there is no diff, and the
10089 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10090 and preferably contains a directory named
10091 <file><var>package</var>-<var>version</var></file>.
10096 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10099 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10100 Debian source package. However, if it is not available it
10101 is possible to unpack a Debian source archive as follows:
10102 <enumlist compact="compact">
10105 Untar the tarfile, which will create a <file>.orig</file>
10109 <p>Rename the <file>.orig</file> directory to
10110 <file><var>package</var>-<var>version</var></file>.</p>
10114 Create the subdirectory <file>debian</file> at the top of
10115 the source tree.</p>
10117 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10119 <item><p>Untar the tarfile again if you want a copy of the original
10120 source code alongside the Debianised version.</p>
10125 It is not possible to generate a valid Debian source archive
10126 without using <prgn>dpkg-source</prgn>. In particular,
10127 attempting to use <prgn>diff</prgn> directly to generate the
10128 <file>.diff.gz</file> file will not work.
10132 <heading>Restrictions on objects in source packages</heading>
10135 The source package may not contain any hard links
10137 This is not currently detected when building source
10138 packages, but only when extracting
10142 Hard links may be permitted at some point in the
10143 future, but would require a fair amount of
10145 </footnote>, device special files, sockets or setuid or
10148 Setgid directories are allowed.
10153 The source packaging tools manage the changes between the
10154 original and Debianised source using <prgn>diff</prgn> and
10155 <prgn>patch</prgn>. Turning the original source tree as
10156 included in the <file>.orig.tar.gz</file> into the debianised
10157 source must not involve any changes which cannot be
10158 handled by these tools. Problematic changes which cause
10159 <prgn>dpkg-source</prgn> to halt with an error when
10160 building the source package are:
10161 <list compact="compact">
10162 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10164 <item><p>Changing the targets of symbolic links.</p>
10166 <item><p>Creating directories, other than <file>debian</file>.</p>
10168 <item><p>Changes to the contents of binary files.</p></item>
10169 </list> Changes which cause <prgn>dpkg-source</prgn> to
10170 print a warning but continue anyway are:
10171 <list compact="compact">
10174 Removing files, directories or symlinks.
10176 Renaming a file is not treated specially - it is
10177 seen as the removal of the old file (which
10178 generates a warning, but is otherwise ignored),
10179 and the creation of the new one.
10185 Changed text files which are missing the usual final
10186 newline (either in the original or the modified
10191 Changes which are not represented, but which are not detected by
10192 <prgn>dpkg-source</prgn>, are:
10193 <list compact="compact">
10194 <item><p>Changing the permissions of files (other than
10195 <file>debian/rules</file>) and directories.</p></item>
10200 The <file>debian</file> directory and <file>debian/rules</file>
10201 are handled specially by <prgn>dpkg-source</prgn> - before
10202 applying the changes it will create the <file>debian</file>
10203 directory, and afterwards it will make
10204 <file>debian/rules</file> world-executable.
10210 <appendix id="pkg-controlfields">
10211 <heading>Control files and their fields (from old Packaging Manual)</heading>
10214 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10215 data in a common format, known as control files. Binary and
10216 source packages have control data as do the <file>.changes</file>
10217 files which control the installation of uploaded files, and
10218 <prgn>dpkg</prgn>'s internal databases are in a similar
10223 <heading>Syntax of control files</heading>
10226 See <ref id="controlsyntax">.
10230 It is important to note that there are several fields which
10231 are optional as far as <prgn>dpkg</prgn> and the related
10232 tools are concerned, but which must appear in every Debian
10233 package, or whose omission may cause problems.
10238 <heading>List of fields</heading>
10241 See <ref id="controlfieldslist">.
10245 This section now contains only the fields that didn't belong
10246 to the Policy manual.
10249 <sect1 id="pkg-f-Filename">
10250 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10253 These fields in <tt>Packages</tt> files give the
10254 filename(s) of (the parts of) a package in the
10255 distribution directories, relative to the root of the
10256 Debian hierarchy. If the package has been split into
10257 several parts the parts are all listed in order, separated
10262 <sect1 id="pkg-f-Size">
10263 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10266 These fields in <file>Packages</file> files give the size (in
10267 bytes, expressed in decimal) and MD5 checksum of the
10268 file(s) which make(s) up a binary package in the
10269 distribution. If the package is split into several parts
10270 the values for the parts are listed in order, separated by
10275 <sect1 id="pkg-f-Status">
10276 <heading><tt>Status</tt></heading>
10279 This field in <prgn>dpkg</prgn>'s status file records
10280 whether the user wants a package installed, removed or
10281 left alone, whether it is broken (requiring
10282 re-installation) or not and what its current state on the
10283 system is. Each of these pieces of information is a
10288 <sect1 id="pkg-f-Config-Version">
10289 <heading><tt>Config-Version</tt></heading>
10292 If a package is not installed or not configured, this
10293 field in <prgn>dpkg</prgn>'s status file records the last
10294 version of the package which was successfully
10299 <sect1 id="pkg-f-Conffiles">
10300 <heading><tt>Conffiles</tt></heading>
10303 This field in <prgn>dpkg</prgn>'s status file contains
10304 information about the automatically-managed configuration
10305 files held by a package. This field should <em>not</em>
10306 appear anywhere in a package!
10311 <heading>Obsolete fields</heading>
10314 These are still recognized by <prgn>dpkg</prgn> but should
10315 not appear anywhere any more.
10317 <taglist compact="compact">
10319 <tag><tt>Revision</tt></tag>
10320 <tag><tt>Package-Revision</tt></tag>
10321 <tag><tt>Package_Revision</tt></tag>
10323 The Debian revision part of the package version was
10324 at one point in a separate control file field. This
10325 field went through several names.
10328 <tag><tt>Recommended</tt></tag>
10329 <item>Old name for <tt>Recommends</tt>.</item>
10331 <tag><tt>Optional</tt></tag>
10332 <item>Old name for <tt>Suggests</tt>.</item>
10334 <tag><tt>Class</tt></tag>
10335 <item>Old name for <tt>Priority</tt>.</item>
10344 <appendix id="pkg-conffiles">
10345 <heading>Configuration file handling (from old Packaging Manual)</heading>
10348 <prgn>dpkg</prgn> can do a certain amount of automatic
10349 handling of package configuration files.
10353 Whether this mechanism is appropriate depends on a number of
10354 factors, but basically there are two approaches to any
10355 particular configuration file.
10359 The easy method is to ship a best-effort configuration in the
10360 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10361 handle updates. If the user is unlikely to want to edit the
10362 file, but you need them to be able to without losing their
10363 changes, and a new package with a changed version of the file
10364 is only released infrequently, this is a good approach.
10368 The hard method is to build the configuration file from
10369 scratch in the <prgn>postinst</prgn> script, and to take the
10370 responsibility for fixing any mistakes made in earlier
10371 versions of the package automatically. This will be
10372 appropriate if the file is likely to need to be different on
10376 <sect><heading>Automatic handling of configuration files by
10381 A package may contain a control area file called
10382 <tt>conffiles</tt>. This file should be a list of filenames
10383 of configuration files needing automatic handling, separated
10384 by newlines. The filenames should be absolute pathnames,
10385 and the files referred to should actually exist in the
10390 When a package is upgraded <prgn>dpkg</prgn> will process
10391 the configuration files during the configuration stage,
10392 shortly before it runs the package's <prgn>postinst</prgn>
10397 For each file it checks to see whether the version of the
10398 file included in the package is the same as the one that was
10399 included in the last version of the package (the one that is
10400 being upgraded from); it also compares the version currently
10401 installed on the system with the one shipped with the last
10406 If neither the user nor the package maintainer has changed
10407 the file, it is left alone. If one or the other has changed
10408 their version, then the changed version is preferred - i.e.,
10409 if the user edits their file, but the package maintainer
10410 doesn't ship a different version, the user's changes will
10411 stay, silently, but if the maintainer ships a new version
10412 and the user hasn't edited it the new version will be
10413 installed (with an informative message). If both have
10414 changed their version the user is prompted about the problem
10415 and must resolve the differences themselves.
10419 The comparisons are done by calculating the MD5 message
10420 digests of the files, and storing the MD5 of the file as it
10421 was included in the most recent version of the package.
10425 When a package is installed for the first time
10426 <prgn>dpkg</prgn> will install the file that comes with it,
10427 unless that would mean overwriting a file already on the
10432 However, note that <prgn>dpkg</prgn> will <em>not</em>
10433 replace a conffile that was removed by the user (or by a
10434 script). This is necessary because with some programs a
10435 missing file produces an effect hard or impossible to
10436 achieve in another way, so that a missing file needs to be
10437 kept that way if the user did it.
10441 Note that a package should <em>not</em> modify a
10442 <prgn>dpkg</prgn>-handled conffile in its maintainer
10443 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10444 the user confusing and possibly dangerous options for
10445 conffile update when the package is upgraded.</p>
10448 <sect><heading>Fully-featured maintainer script configuration
10453 For files which contain site-specific information such as
10454 the hostname and networking details and so forth, it is
10455 better to create the file in the package's
10456 <prgn>postinst</prgn> script.
10460 This will typically involve examining the state of the rest
10461 of the system to determine values and other information, and
10462 may involve prompting the user for some information which
10463 can't be obtained some other way.
10467 When using this method there are a couple of important
10468 issues which should be considered:
10472 If you discover a bug in the program which generates the
10473 configuration file, or if the format of the file changes
10474 from one version to the next, you will have to arrange for
10475 the postinst script to do something sensible - usually this
10476 will mean editing the installed configuration file to remove
10477 the problem or change the syntax. You will have to do this
10478 very carefully, since the user may have changed the file,
10479 perhaps to fix the very problem that your script is trying
10480 to deal with - you will have to detect these situations and
10481 deal with them correctly.
10485 If you do go down this route it's probably a good idea to
10486 make the program that generates the configuration file(s) a
10487 separate program in <file>/usr/sbin</file>, by convention called
10488 <file><var>package</var>config</file> and then run that if
10489 appropriate from the post-installation script. The
10490 <tt><var>package</var>config</tt> program should not
10491 unquestioningly overwrite an existing configuration - if its
10492 mode of operation is geared towards setting up a package for
10493 the first time (rather than any arbitrary reconfiguration
10494 later) you should have it check whether the configuration
10495 already exists, and require a <tt>--force</tt> flag to
10496 overwrite it.</p></sect>
10499 <appendix id="pkg-alternatives"><heading>Alternative versions of
10500 an interface - <prgn>update-alternatives</prgn> (from old
10505 When several packages all provide different versions of the
10506 same program or file it is useful to have the system select a
10507 default, but to allow the system administrator to change it
10508 and have their decisions respected.
10512 For example, there are several versions of the <prgn>vi</prgn>
10513 editor, and there is no reason to prevent all of them from
10514 being installed at once, each under their own name
10515 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10516 Nevertheless it is desirable to have the name <tt>vi</tt>
10517 refer to something, at least by default.
10521 If all the packages involved cooperate, this can be done with
10522 <prgn>update-alternatives</prgn>.
10526 Each package provides its own version under its own name, and
10527 calls <prgn>update-alternatives</prgn> in its postinst to
10528 register its version (and again in its prerm to deregister
10533 See the man page <manref name="update-alternatives"
10534 section="8"> for details.
10538 If <prgn>update-alternatives</prgn> does not seem appropriate
10539 you may wish to consider using diversions instead.</p>
10542 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10543 package's version of a file (from old Packaging Manual)
10547 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10548 when it reinstalls the package it belongs to, and to have it
10549 put the file from the package somewhere else instead.
10553 This can be used locally to override a package's version of a
10554 file, or by one package to override another's version (or
10555 provide a wrapper for it).
10559 Before deciding to use a diversion, read <ref
10560 id="pkg-alternatives"> to see if you really want a diversion
10561 rather than several alternative versions of a program.
10565 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10566 and updated by a special program <prgn>dpkg-divert</prgn>.
10567 Please see <manref name="dpkg-divert" section="8"> for full
10568 details of its operation.
10572 When a package wishes to divert a file from another, it should
10573 call <prgn>dpkg-divert</prgn> in its preinst to add the
10574 diversion and rename the existing file. For example,
10575 supposing that a <prgn>smailwrapper</prgn> package wishes to
10576 install a wrapper around <file>/usr/sbin/smail</file>:
10578 if [ install = "$1" ]; then
10579 dpkg-divert --package smailwrapper --add --rename \
10580 --divert /usr/sbin/smail.real /usr/sbin/smail
10582 </example> Testing <tt>$1</tt> is necessary so that the script
10583 doesn't try to add the diversion again when
10584 <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
10585 smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
10586 copy of <file>/usr/sbin/smail</file> can bypass the diversion and
10587 get installed as the true version.
10591 The postrm has to do the reverse:
10593 if [ remove = "$1" ]; then
10594 dpkg-divert --package smailwrapper --remove --rename \
10595 --divert /usr/sbin/smail.real /usr/sbin/smail
10601 Do not attempt to divert a file which is vitally important for
10602 the system's operation - when using <prgn>dpkg-divert</prgn>
10603 there is a time, after it has been diverted but before
10604 <prgn>dpkg</prgn> has installed the new version, when the file
10605 does not exist.</p>
10610 <!-- Local variables: -->
10611 <!-- indent-tabs-mode: t -->
10613 <!-- vim:set ai et sts=2 sw=2 tw=76: -->