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10 <title>Debian Policy Manual</title>
11 <author><qref id="authors">The Debian Policy Mailing List</qref></author>
12 <version>version &version;, &date;</version>
15 This manual describes the policy requirements for the Debian
16 GNU/Linux distribution. This includes the structure and
17 contents of the Debian archive and several design issues of
18 the operating system, as well as technical requirements that
19 each package must satisfy to be included in the distribution.
24 Copyright © 1996,1997,1998 Ian Jackson
25 and Christian Schwarz.
28 These are the copyright dates of the original Policy manual.
29 Since then, this manual has been updated by many others. No
30 comprehensive collection of copyright notices for subsequent
35 This manual is free software; you may redistribute it and/or
36 modify it under the terms of the GNU General Public License
37 as published by the Free Software Foundation; either version
38 2, or (at your option) any later version.
42 This is distributed in the hope that it will be useful, but
43 <em>without any warranty</em>; without even the implied
44 warranty of merchantability or fitness for a particular
45 purpose. See the GNU General Public License for more
50 A copy of the GNU General Public License is available as
51 <file>/usr/share/common-licenses/GPL</file> in the Debian GNU/Linux
52 distribution or on the World Wide Web at
53 <url id="http://www.gnu.org/copyleft/gpl.html"
54 name="the GNU General Public Licence">. You can also
55 obtain it by writing to the Free Software Foundation, Inc.,
56 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
64 <heading>About this manual</heading>
66 <heading>Scope</heading>
68 This manual describes the policy requirements for the Debian
69 GNU/Linux distribution. This includes the structure and
70 contents of the Debian archive and several design issues of the
71 operating system, as well as technical requirements that
72 each package must satisfy to be included in the
77 This manual also describes Debian policy as it relates to
78 creating Debian packages. It is not a tutorial on how to build
79 packages, nor is it exhaustive where it comes to describing
80 the behavior of the packaging system. Instead, this manual
81 attempts to define the interface to the package management
82 system that the developers have to be conversant with.<footnote>
83 Informally, the criteria used for inclusion is that the
84 material meet one of the following requirements:
85 <taglist compact="compact">
86 <tag>Standard interfaces</tag>
88 The material presented represents an interface to
89 the packaging system that is mandated for use, and
90 is used by, a significant number of packages, and
91 therefore should not be changed without peer
92 review. Package maintainers can then rely on this
93 interfaces not changing, and the package
94 management software authors need to ensure
95 compatibility with these interface
96 definitions. (Control file and changelog file
97 formats are examples.)
99 <tag>Chosen Convention</tag>
101 If there are a number of technically viable choices
102 that can be made, but one needs to select one of
103 these options for inter-operability. The version
104 number format is one example.
107 Please note that these are not mutually exclusive;
108 selected conventions often become parts of standard
114 The footnotes present in this manual are
115 merely informative, and are not part of Debian policy itself.
119 The appendices to this manual are not necessarily normative,
120 either. Please see <ref id="pkg-scope"> for more information.
124 In the normative part of this manual,
125 the words <em>must</em>, <em>should</em> and
126 <em>may</em>, and the adjectives <em>required</em>,
127 <em>recommended</em> and <em>optional</em>, are used to
128 distinguish the significance of the various guidelines in
129 this policy document. Packages that do not conform to the
130 guidelines denoted by <em>must</em> (or <em>required</em>)
131 will generally not be considered acceptable for the Debian
132 distribution. Non-conformance with guidelines denoted by
133 <em>should</em> (or <em>recommended</em>) will generally be
134 considered a bug, but will not necessarily render a package
135 unsuitable for distribution. Guidelines denoted by
136 <em>may</em> (or <em>optional</em>) are truly optional and
137 adherence is left to the maintainer's discretion.
141 These classifications are roughly equivalent to the bug
142 severities <em>serious</em> (for <em>must</em> or
143 <em>required</em> directive violations), <em>minor</em>,
144 <em>normal</em> or <em>important</em>
145 (for <em>should</em> or <em>recommended</em> directive
146 violations) and <em>wishlist</em> (for <em>optional</em>
149 Compare RFC 2119. Note, however, that these words are
150 used in a different way in this document.
155 Much of the information presented in this manual will be
156 useful even when building a package which is to be
157 distributed in some other way or is intended for local use
163 <heading>New versions of this document</heading>
166 This manual is distributed via the Debian package
167 <package><url name="debian-policy"
168 id="http://packages.debian.org/debian-policy"></package>
169 (<httpsite>packages.debian.org</httpsite>
170 <httppath>/debian-policy</httppath>).
174 The current version of this document is also available from
175 the Debian web mirrors at
176 <tt><url name="/doc/debian-policy/"
177 id="http://www.debian.org/doc/debian-policy/"></tt>.
179 <httpsite>www.debian.org</httpsite>
180 <httppath>/doc/debian-policy/</httppath>)
181 Also available from the same directory are several other
182 formats: <file>policy.html.tar.gz</file>
183 (<httppath>/doc/debian-policy/policy.html.tar.gz</httppath>),
184 <file>policy.pdf.gz</file>
185 (<httppath>/doc/debian-policy/policy.pdf.gz</httppath>)
186 and <file>policy.ps.gz</file>
187 (<httppath>/doc/debian-policy/policy.ps.gz</httppath>).
191 The <package>debian-policy</package> package also includes the file
192 <file>upgrading-checklist.txt.gz</file> which indicates policy
193 changes between versions of this document.
198 <heading>Authors and Maintainers</heading>
201 Originally called "Debian GNU/Linux Policy Manual", this
202 manual was initially written in 1996 by Ian Jackson.
203 It was revised on November 27th, 1996 by David A. Morris.
204 Christian Schwarz added new sections on March 15th, 1997,
205 and reworked/restructured it in April-July 1997.
206 Christoph Lameter contributed the "Web Standard".
207 Julian Gilbey largely restructured it in 2001.
211 Since September 1998, the responsibility for the contents of
212 this document lies on the <url name="debian-policy mailing list"
213 id="mailto:debian-policy@lists.debian.org">. Proposals
214 are discussed there and inserted into policy after a certain
215 consensus is established.
216 <!-- insert shameless policy-process plug here eventually -->
217 The actual editing is done by a group of maintainers that have
218 no editorial powers. These are the current maintainers:
221 <item>Julian Gilbey</item>
222 <item>Branden Robinson</item>
223 <item>Josip Rodin</item>
224 <item>Manoj Srivastava</item>
229 While the authors of this document have tried hard to avoid
230 typos and other errors, these do still occur. If you discover
231 an error in this manual or if you want to give any
232 comments, suggestions, or criticisms please send an email to
233 the Debian Policy List,
234 <email>debian-policy@lists.debian.org</email>, or submit a
235 bug report against the <tt>debian-policy</tt> package.
239 Please do not try to reach the individual authors or maintainers
240 of the Policy Manual regarding changes to the Policy.
245 <heading>Related documents</heading>
248 There are several other documents other than this Policy Manual
249 that are necessary to fully understand some Debian policies and
254 The external "sub-policy" documents are referred to in:
255 <list compact="compact">
256 <item><ref id="fhs"></item>
257 <item><ref id="virtual_pkg"></item>
258 <item><ref id="menus"></item>
259 <item><ref id="mime"></item>
260 <item><ref id="perl"></item>
261 <item><ref id="maintscriptprompt"></item>
262 <item><ref id="emacs"></item>
267 In addition to those, which carry the weight of policy, there
268 is the Debian Developer's Reference. This document describes
269 procedures and resources for Debian developers, but it is
270 <em>not</em> normative; rather, it includes things that don't
271 belong in the Policy, such as best practices for developers.
275 The Developer's Reference is available in the
276 <package>developers-reference</package> package.
277 It's also available from the Debian web mirrors at
278 <tt><url name="/doc/developers-reference/"
279 id="http://www.debian.org/doc/developers-reference/"></tt>.
283 <sect id="definitions">
284 <heading>Definitions</heading>
287 The following terms are used in this Policy Manual:
291 The character encoding specified by ANSI X3.4-1986 and its
292 predecessor standards, referred to in MIME as US-ASCII, and
293 corresponding to an encoding in eight bits per character of
294 the first 128 <url id="http://www.unicode.org/"
295 name="Unicode"> characters, with the eighth bit always zero.
299 The transformation format (sometimes called encoding) of
300 <url id="http://www.unicode.org/" name="Unicode"> defined by
301 <url id="http://www.rfc-editor.org/rfc/rfc3629.txt"
302 name="RFC 3629">. UTF-8 has the useful property of having
303 ASCII as a subset, so any text encoded in ASCII is trivially
313 <heading>The Debian Archive</heading>
316 The Debian GNU/Linux system is maintained and distributed as a
317 collection of <em>packages</em>. Since there are so many of
318 them (currently well over 15000), they are split into
319 <em>sections</em> and given <em>priorities</em> to simplify
320 the handling of them.
324 The effort of the Debian project is to build a free operating
325 system, but not every package we want to make accessible is
326 <em>free</em> in our sense (see the Debian Free Software
327 Guidelines, below), or may be imported/exported without
328 restrictions. Thus, the archive is split into areas<footnote>
329 The Debian archive software uses the term "component" internally
330 and in the Release file format to refer to the division of an
331 archive. The Debian Social Contract simply refers to "areas."
332 This document uses terminology similar to the Social Contract.
333 </footnote> based on their licenses and other restrictions.
337 The aims of this are:
339 <list compact="compact">
340 <item>to allow us to make as much software available as we can</item>
341 <item>to allow us to encourage everyone to write free software,
343 <item>to allow us to make it easy for people to produce
344 CD-ROMs of our system without violating any licenses,
345 import/export restrictions, or any other laws.</item>
350 The <em>main</em> archive area forms the <em>Debian GNU/Linux
355 Packages in the other archive areas (<tt>contrib</tt>,
356 <tt>non-free</tt>) are not considered to be part of the Debian
357 distribution, although we support their use and provide
358 infrastructure for them (such as our bug-tracking system and
359 mailing lists). This Debian Policy Manual applies to these
364 <heading>The Debian Free Software Guidelines</heading>
366 The Debian Free Software Guidelines (DFSG) form our
367 definition of "free software". These are:
369 <tag>1. Free Redistribution
372 The license of a Debian component may not restrict any
373 party from selling or giving away the software as a
374 component of an aggregate software distribution
375 containing programs from several different
376 sources. The license may not require a royalty or
377 other fee for such sale.
382 The program must include source code, and must allow
383 distribution in source code as well as compiled form.
385 <tag>3. Derived Works
388 The license must allow modifications and derived
389 works, and must allow them to be distributed under the
390 same terms as the license of the original software.
392 <tag>4. Integrity of The Author's Source Code
395 The license may restrict source-code from being
396 distributed in modified form <em>only</em> if the
397 license allows the distribution of "patch files"
398 with the source code for the purpose of modifying the
399 program at build time. The license must explicitly
400 permit distribution of software built from modified
401 source code. The license may require derived works to
402 carry a different name or version number from the
403 original software. (This is a compromise. The Debian
404 Project encourages all authors to not restrict any
405 files, source or binary, from being modified.)
407 <tag>5. No Discrimination Against Persons or Groups
410 The license must not discriminate against any person
413 <tag>6. No Discrimination Against Fields of Endeavor
416 The license must not restrict anyone from making use
417 of the program in a specific field of endeavor. For
418 example, it may not restrict the program from being
419 used in a business, or from being used for genetic
422 <tag>7. Distribution of License
425 The rights attached to the program must apply to all
426 to whom the program is redistributed without the need
427 for execution of an additional license by those
430 <tag>8. License Must Not Be Specific to Debian
433 The rights attached to the program must not depend on
434 the program's being part of a Debian system. If the
435 program is extracted from Debian and used or
436 distributed without Debian but otherwise within the
437 terms of the program's license, all parties to whom
438 the program is redistributed must have the same
439 rights as those that are granted in conjunction with
442 <tag>9. License Must Not Contaminate Other Software
445 The license must not place restrictions on other
446 software that is distributed along with the licensed
447 software. For example, the license must not insist
448 that all other programs distributed on the same medium
449 must be free software.
451 <tag>10. Example Licenses
454 The "GPL," "BSD," and "Artistic" licenses are examples of
455 licenses that we consider <em>free</em>.
462 <heading>Archive areas</heading>
465 <heading>The main archive area</heading>
468 Every package in <em>main</em> must comply with the DFSG
469 (Debian Free Software Guidelines).
473 In addition, the packages in <em>main</em>
474 <list compact="compact">
476 must not require a package outside of <em>main</em>
477 for compilation or execution (thus, the package must
478 not declare a "Depends", "Recommends", or
479 "Build-Depends" relationship on a non-<em>main</em>
483 must not be so buggy that we refuse to support them,
487 must meet all policy requirements presented in this
496 <heading>The contrib archive area</heading>
499 Every package in <em>contrib</em> must comply with the DFSG.
503 In addition, the packages in <em>contrib</em>
504 <list compact="compact">
506 must not be so buggy that we refuse to support them,
510 must meet all policy requirements presented in this
518 Examples of packages which would be included in
519 <em>contrib</em> are:
520 <list compact="compact">
522 free packages which require <em>contrib</em>,
523 <em>non-free</em> packages or packages which are not
524 in our archive at all for compilation or execution,
528 wrapper packages or other sorts of free accessories for
535 <sect1 id="non-free">
536 <heading>The non-free archive area</heading>
539 Packages must be placed in <em>non-free</em> if they are
540 not compliant with the DFSG or are encumbered by patents
541 or other legal issues that make their distribution
546 In addition, the packages in <em>non-free</em>
547 <list compact="compact">
549 must not be so buggy that we refuse to support them,
553 must meet all policy requirements presented in this
554 manual that it is possible for them to meet.
556 It is possible that there are policy
557 requirements which the package is unable to
558 meet, for example, if the source is
559 unavailable. These situations will need to be
560 handled on a case-by-case basis.
569 <sect id="pkgcopyright">
570 <heading>Copyright considerations</heading>
573 Every package must be accompanied by a verbatim copy of
574 its copyright and distribution license in the file
575 <file>/usr/share/doc/<var>package</var>/copyright</file>
576 (see <ref id="copyrightfile"> for further details).
580 We reserve the right to restrict files from being included
581 anywhere in our archives if
582 <list compact="compact">
584 their use or distribution would break a law,
587 there is an ethical conflict in their distribution or
591 we would have to sign a license for them, or
594 their distribution would conflict with other project
601 Programs whose authors encourage the user to make
602 donations are fine for the main distribution, provided
603 that the authors do not claim that not donating is
604 immoral, unethical, illegal or something similar; in such
605 a case they must go in <em>non-free</em>.
609 Packages whose copyright permission notices (or patent
610 problems) do not even allow redistribution of binaries
611 only, and where no special permission has been obtained,
612 must not be placed on the Debian FTP site and its mirrors
617 Note that under international copyright law (this applies
618 in the United States, too), <em>no</em> distribution or
619 modification of a work is allowed without an explicit
620 notice saying so. Therefore a program without a copyright
621 notice <em>is</em> copyrighted and you may not do anything
622 to it without risking being sued! Likewise if a program
623 has a copyright notice but no statement saying what is
624 permitted then nothing is permitted.
628 Many authors are unaware of the problems that restrictive
629 copyrights (or lack of copyright notices) can cause for
630 the users of their supposedly-free software. It is often
631 worthwhile contacting such authors diplomatically to ask
632 them to modify their license terms. However, this can be a
633 politically difficult thing to do and you should ask for
634 advice on the <tt>debian-legal</tt> mailing list first, as
639 When in doubt about a copyright, send mail to
640 <email>debian-legal@lists.debian.org</email>. Be prepared
641 to provide us with the copyright statement. Software
642 covered by the GPL, public domain software and BSD-like
643 copyrights are safe; be wary of the phrases "commercial
644 use prohibited" and "distribution restricted".
648 <sect id="subsections">
649 <heading>Sections</heading>
652 The packages in the archive areas <em>main</em>,
653 <em>contrib</em> and <em>non-free</em> are grouped further into
654 <em>sections</em> to simplify handling.
658 The archive area and section for each package should be
659 specified in the package's <tt>Section</tt> control record (see
660 <ref id="f-Section">). However, the maintainer of the Debian
661 archive may override this selection to ensure the consistency of
662 the Debian distribution. The <tt>Section</tt> field should be
664 <list compact="compact">
666 <em>section</em> if the package is in the
667 <em>main</em> archive area,
670 <em>area/section</em> if the package is in
671 the <em>contrib</em> or <em>non-free</em>
678 The Debian archive maintainers provide the authoritative
679 list of sections. At present, they are:
680 <em>admin</em>, <em>cli-mono</em>, <em>comm</em>, <em>database</em>,
681 <em>devel</em>, <em>debug</em>, <em>doc</em>, <em>editors</em>,
682 <em>electronics</em>, <em>embedded</em>, <em>fonts</em>,
683 <em>games</em>, <em>gnome</em>, <em>graphics</em>, <em>gnu-r</em>,
684 <em>gnustep</em>, <em>hamradio</em>, <em>haskell</em>,
685 <em>httpd</em>, <em>interpreters</em>, <em>java</em>, <em>kde</em>,
686 <em>kernel</em>, <em>libs</em>, <em>libdevel</em>, <em>lisp</em>,
687 <em>localization</em>, <em>mail</em>, <em>math</em>, <em>misc</em>,
688 <em>net</em>, <em>news</em>, <em>ocaml</em>, <em>oldlibs</em>,
689 <em>otherosfs</em>, <em>perl</em>, <em>php</em>, <em>python</em>,
690 <em>ruby</em>, <em>science</em>, <em>shells</em>, <em>sound</em>,
691 <em>tex</em>, <em>text</em>, <em>utils</em>, <em>vcs</em>,
692 <em>video</em>, <em>web</em>, <em>x11</em>, <em>xfce</em>,
697 <sect id="priorities">
698 <heading>Priorities</heading>
701 Each package should have a <em>priority</em> value, which is
702 included in the package's <em>control record</em>
703 (see <ref id="f-Priority">).
704 This information is used by the Debian package management tools to
705 separate high-priority packages from less-important packages.
709 The following <em>priority levels</em> are recognized by the
710 Debian package management tools.
712 <tag><tt>required</tt></tag>
714 Packages which are necessary for the proper
715 functioning of the system (usually, this means that
716 dpkg functionality depends on these packages).
717 Removing a <tt>required</tt> package may cause your
718 system to become totally broken and you may not even
719 be able to use <prgn>dpkg</prgn> to put things back,
720 so only do so if you know what you are doing. Systems
721 with only the <tt>required</tt> packages are probably
722 unusable, but they do have enough functionality to
723 allow the sysadmin to boot and install more software.
725 <tag><tt>important</tt></tag>
727 Important programs, including those which one would
728 expect to find on any Unix-like system. If the
729 expectation is that an experienced Unix person who
730 found it missing would say "What on earth is going on,
731 where is <prgn>foo</prgn>?", it must be an
732 <tt>important</tt> package.<footnote>
733 This is an important criterion because we are
734 trying to produce, amongst other things, a free
737 Other packages without which the system will not run
738 well or be usable must also have priority
739 <tt>important</tt>. This does
740 <em>not</em> include Emacs, the X Window System, TeX
741 or any other large applications. The
742 <tt>important</tt> packages are just a bare minimum of
743 commonly-expected and necessary tools.
745 <tag><tt>standard</tt></tag>
747 These packages provide a reasonably small but not too
748 limited character-mode system. This is what will be
749 installed by default if the user doesn't select anything
750 else. It doesn't include many large applications.
752 <tag><tt>optional</tt></tag>
754 (In a sense everything that isn't required is
755 optional, but that's not what is meant here.) This is
756 all the software that you might reasonably want to
757 install if you didn't know what it was and don't have
758 specialized requirements. This is a much larger system
759 and includes the X Window System, a full TeX
760 distribution, and many applications. Note that
761 optional packages should not conflict with each other.
763 <tag><tt>extra</tt></tag>
765 This contains all packages that conflict with others
766 with required, important, standard or optional
767 priorities, or are only likely to be useful if you
768 already know what they are or have specialized
769 requirements (such as packages containing only detached
776 Packages must not depend on packages with lower priority
777 values (excluding build-time dependencies). In order to
778 ensure this, the priorities of one or more packages may need
787 <heading>Binary packages</heading>
790 The Debian GNU/Linux distribution is based on the Debian
791 package management system, called <prgn>dpkg</prgn>. Thus,
792 all packages in the Debian distribution must be provided
793 in the <tt>.deb</tt> file format.
797 <heading>The package name</heading>
800 Every package must have a name that's unique within the Debian
805 The package name is included in the control field
806 <tt>Package</tt>, the format of which is described
807 in <ref id="f-Package">.
808 The package name is also included as a part of the file name
809 of the <tt>.deb</tt> file.
814 <heading>The version of a package</heading>
817 Every package has a version number recorded in its
818 <tt>Version</tt> control file field, described in
819 <ref id="f-Version">.
823 The package management system imposes an ordering on version
824 numbers, so that it can tell whether packages are being up- or
825 downgraded and so that package system front end applications
826 can tell whether a package it finds available is newer than
827 the one installed on the system. The version number format
828 has the most significant parts (as far as comparison is
829 concerned) at the beginning.
833 If an upstream package has problematic version numbers they
834 should be converted to a sane form for use in the
835 <tt>Version</tt> field.
839 <heading>Version numbers based on dates</heading>
842 In general, Debian packages should use the same version
843 numbers as the upstream sources.
847 However, in some cases where the upstream version number is
848 based on a date (e.g., a development "snapshot" release) the
849 package management system cannot handle these version
850 numbers without epochs. For example, dpkg will consider
851 "96May01" to be greater than "96Dec24".
855 To prevent having to use epochs for every new upstream
856 version, the date based portion of the version number
857 should be changed to the following format in such cases:
858 "19960501", "19961224". It is up to the maintainer whether
859 they want to bother the upstream maintainer to change
860 the version numbers upstream, too.
864 Note that other version formats based on dates which are
865 parsed correctly by the package management system should
866 <em>not</em> be changed.
870 Native Debian packages (i.e., packages which have been
871 written especially for Debian) whose version numbers include
872 dates should always use the "YYYYMMDD" format.
879 <heading>The maintainer of a package</heading>
882 Every package must have a Debian maintainer (the
883 maintainer may be one person or a group of people
884 reachable from a common email address, such as a mailing
885 list). The maintainer is responsible for ensuring that
886 the package is placed in the appropriate distributions.
890 The maintainer must be specified in the
891 <tt>Maintainer</tt> control field with their correct name
892 and a working email address. If one person maintains
893 several packages, they should try to avoid having
894 different forms of their name and email address in
895 the <tt>Maintainer</tt> fields of those packages.
899 The format of the <tt>Maintainer</tt> control field is
900 described in <ref id="f-Maintainer">.
904 If the maintainer of a package quits from the Debian
905 project, "Debian QA Group"
906 <email>packages@qa.debian.org</email> takes over the
907 maintainer-ship of the package until someone else
908 volunteers for that task. These packages are called
909 <em>orphaned packages</em>.<footnote>
910 The detailed procedure for doing this gracefully can
911 be found in the Debian Developer's Reference,
912 see <ref id="related">.
917 <sect id="descriptions">
918 <heading>The description of a package</heading>
921 Every Debian package must have an extended description
922 stored in the appropriate field of the control record.
923 The technical information about the format of the
924 <tt>Description</tt> field is in <ref id="f-Description">.
928 The description should describe the package (the program) to a
929 user (system administrator) who has never met it before so that
930 they have enough information to decide whether they want to
931 install it. This description should not just be copied verbatim
932 from the program's documentation.
936 Put important information first, both in the synopsis and
937 extended description. Sometimes only the first part of the
938 synopsis or of the description will be displayed. You can
939 assume that there will usually be a way to see the whole
940 extended description.
944 The description should also give information about the
945 significant dependencies and conflicts between this package
946 and others, so that the user knows why these dependencies and
947 conflicts have been declared.
951 Instructions for configuring or using the package should
952 not be included (that is what installation scripts,
953 manual pages, info files, etc., are for). Copyright
954 statements and other administrivia should not be included
955 either (that is what the copyright file is for).
958 <sect1 id="synopsis"><heading>The single line synopsis</heading>
961 The single line synopsis should be kept brief - certainly
966 Do not include the package name in the synopsis line. The
967 display software knows how to display this already, and you
968 do not need to state it. Remember that in many situations
969 the user may only see the synopsis line - make it as
970 informative as you can.
975 <sect1 id="extendeddesc"><heading>The extended description</heading>
978 Do not try to continue the single line synopsis into the
979 extended description. This will not work correctly when
980 the full description is displayed, and makes no sense
981 where only the summary (the single line synopsis) is
986 The extended description should describe what the package
987 does and how it relates to the rest of the system (in terms
988 of, for example, which subsystem it is which part of).
992 The description field needs to make sense to anyone, even
993 people who have no idea about any of the things the
994 package deals with.<footnote>
995 The blurb that comes with a program in its
996 announcements and/or <prgn>README</prgn> files is
997 rarely suitable for use in a description. It is
998 usually aimed at people who are already in the
999 community where the package is used.
1008 <heading>Dependencies</heading>
1011 Every package must specify the dependency information
1012 about other packages that are required for the first to
1017 For example, a dependency entry must be provided for any
1018 shared libraries required by a dynamically-linked executable
1019 binary in a package.
1023 Packages are not required to declare any dependencies they
1024 have on other packages which are marked <tt>Essential</tt>
1025 (see below), and should not do so unless they depend on a
1026 particular version of that package.<footnote>
1028 Essential is needed in part to avoid unresolvable dependency
1029 loops on upgrade. If packages add unnecessary dependencies
1030 on packages in this set, the chances that there
1031 <strong>will</strong> be an unresolvable dependency loop
1032 caused by forcing these Essential packages to be configured
1033 first before they need to be is greatly increased. It also
1034 increases the chances that frontends will be unable to
1035 <strong>calculate</strong> an upgrade path, even if one
1039 Also, functionality is rarely ever removed from the
1040 Essential set, but <em>packages</em> have been removed from
1041 the Essential set when the functionality moved to a
1042 different package. So depending on these packages <em>just
1043 in case</em> they stop being essential does way more harm
1050 Sometimes, a package requires another package to be installed
1051 <em>and</em> configured before it can be installed. In this
1052 case, you must specify a <tt>Pre-Depends</tt> entry for
1057 You should not specify a <tt>Pre-Depends</tt> entry for a
1058 package before this has been discussed on the
1059 <tt>debian-devel</tt> mailing list and a consensus about
1060 doing that has been reached.
1064 The format of the package interrelationship control fields is
1065 described in <ref id="relationships">.
1069 <sect id="virtual_pkg">
1070 <heading>Virtual packages</heading>
1073 Sometimes, there are several packages which offer
1074 more-or-less the same functionality. In this case, it's
1075 useful to define a <em>virtual package</em> whose name
1076 describes that common functionality. (The virtual
1077 packages only exist logically, not physically; that's why
1078 they are called <em>virtual</em>.) The packages with this
1079 particular function will then <em>provide</em> the virtual
1080 package. Thus, any other package requiring that function
1081 can simply depend on the virtual package without having to
1082 specify all possible packages individually.
1086 All packages should use virtual package names where
1087 appropriate, and arrange to create new ones if necessary.
1088 They should not use virtual package names (except privately,
1089 amongst a cooperating group of packages) unless they have
1090 been agreed upon and appear in the list of virtual package
1091 names. (See also <ref id="virtual">)
1095 The latest version of the authoritative list of virtual
1096 package names can be found in the <tt>debian-policy</tt> package.
1097 It is also available from the Debian web mirrors at
1098 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1099 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>.
1103 The procedure for updating the list is described in the preface
1110 <heading>Base system</heading>
1113 The <tt>base system</tt> is a minimum subset of the Debian
1114 GNU/Linux system that is installed before everything else
1115 on a new system. Only very few packages are allowed to form
1116 part of the base system, in order to keep the required disk
1121 The base system consists of all those packages with priority
1122 <tt>required</tt> or <tt>important</tt>. Many of them will
1123 be tagged <tt>essential</tt> (see below).
1128 <heading>Essential packages</heading>
1131 Essential is defined as the minimal set of functionality that
1132 must be available and usable on the system at all times, even
1133 when packages are in an unconfigured (but unpacked) state.
1134 Packages are tagged <tt>essential</tt> for a system using the
1135 <tt>Essential</tt> control file field. The format of the
1136 <tt>Essential</tt> control field is described in <ref
1141 Since these packages cannot be easily removed (one has to
1142 specify an extra <em>force option</em> to
1143 <prgn>dpkg</prgn> to do so), this flag must not be used
1144 unless absolutely necessary. A shared library package
1145 must not be tagged <tt>essential</tt>; dependencies will
1146 prevent its premature removal, and we need to be able to
1147 remove it when it has been superseded.
1151 Since dpkg will not prevent upgrading of other packages
1152 while an <tt>essential</tt> package is in an unconfigured
1153 state, all <tt>essential</tt> packages must supply all of
1154 their core functionality even when unconfigured. If the
1155 package cannot satisfy this requirement it must not be
1156 tagged as essential, and any packages depending on this
1157 package must instead have explicit dependency fields as
1162 Maintainers should take great care in adding any programs,
1163 interfaces, or functionality to <tt>essential</tt> packages.
1164 Packages may assume that functionality provided by
1165 <tt>essential</tt> packages is always available without
1166 declaring explicit dependencies, which means that removing
1167 functionality from the Essential set is very difficult and is
1168 almost never done. Any capability added to an
1169 <tt>essential</tt> package therefore creates an obligation to
1170 support that capability as part of the Essential set in
1175 You must not tag any packages <tt>essential</tt> before
1176 this has been discussed on the <tt>debian-devel</tt>
1177 mailing list and a consensus about doing that has been
1182 <sect id="maintscripts">
1183 <heading>Maintainer Scripts</heading>
1186 The package installation scripts should avoid producing
1187 output which is unnecessary for the user to see and
1188 should rely on <prgn>dpkg</prgn> to stave off boredom on
1189 the part of a user installing many packages. This means,
1190 amongst other things, using the <tt>--quiet</tt> option on
1191 <prgn>install-info</prgn>.
1195 Errors which occur during the execution of an installation
1196 script must be checked and the installation must not
1197 continue after an error.
1201 Note that in general <ref id="scripts"> applies to package
1202 maintainer scripts, too.
1206 You should not use <prgn>dpkg-divert</prgn> on a file
1207 belonging to another package without consulting the
1208 maintainer of that package first.
1212 All packages which supply an instance of a common command
1213 name (or, in general, filename) should generally use
1214 <prgn>update-alternatives</prgn>, so that they may be
1215 installed together. If <prgn>update-alternatives</prgn>
1216 is not used, then each package must use
1217 <tt>Conflicts</tt> to ensure that other packages are
1218 de-installed. (In this case, it may be appropriate to
1219 specify a conflict against earlier versions of something
1220 that previously did not use
1221 <prgn>update-alternatives</prgn>; this is an exception to
1222 the usual rule that versioned conflicts should be
1226 <sect1 id="maintscriptprompt">
1227 <heading>Prompting in maintainer scripts</heading>
1229 Package maintainer scripts may prompt the user if
1230 necessary. Prompting must be done by communicating
1231 through a program, such as <prgn>debconf</prgn>, which
1232 conforms to the Debian Configuration Management
1233 Specification, version 2 or higher.
1237 Packages which are essential, or which are dependencies of
1238 essential packages, may fall back on another prompting method
1239 if no such interface is available when they are executed.
1243 The Debian Configuration Management Specification is included
1244 in the <file>debconf_specification</file> files in the
1245 <package>debian-policy</package> package.
1246 It is also available from the Debian web mirrors at
1247 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1248 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>.
1252 Packages which use the Debian Configuration Management
1253 Specification may contain an additional
1254 <prgn>config</prgn> script and a <tt>templates</tt>
1255 file in their control archive<footnote>
1256 The control.tar.gz inside the .deb.
1257 See <manref name="deb" section="5">.
1259 The <prgn>config</prgn> script might be run before the
1260 <prgn>preinst</prgn> script, and before the package is unpacked
1261 or any of its dependencies or pre-dependencies are satisfied.
1262 Therefore it must work using only the tools present in
1263 <em>essential</em> packages.<footnote>
1264 <package>Debconf</package> or another tool that
1265 implements the Debian Configuration Management
1266 Specification will also be installed, and any
1267 versioned dependencies on it will be satisfied
1268 before preconfiguration begins.
1273 Packages which use the Debian Configuration Management
1274 Specification must allow for translation of their user-visible
1275 messages by using a gettext-based system such as the one
1276 provided by the <package>po-debconf</package> package.
1280 Packages should try to minimize the amount of prompting
1281 they need to do, and they should ensure that the user
1282 will only ever be asked each question once. This means
1283 that packages should try to use appropriate shared
1284 configuration files (such as <file>/etc/papersize</file> and
1285 <file>/etc/news/server</file>), and shared
1286 <package>debconf</package> variables rather than each
1287 prompting for their own list of required pieces of
1292 It also means that an upgrade should not ask the same
1293 questions again, unless the user has used
1294 <tt>dpkg --purge</tt> to remove the package's configuration.
1295 The answers to configuration questions should be stored in an
1296 appropriate place in <file>/etc</file> so that the user can
1297 modify them, and how this has been done should be
1302 If a package has a vitally important piece of
1303 information to pass to the user (such as "don't run me
1304 as I am, you must edit the following configuration files
1305 first or you risk your system emitting badly-formatted
1306 messages"), it should display this in the
1307 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1308 prompt the user to hit return to acknowledge the
1309 message. Copyright messages do not count as vitally
1310 important (they belong in
1311 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1312 neither do instructions on how to use a program (these
1313 should be in on-line documentation, where all the users
1318 Any necessary prompting should almost always be confined
1319 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1320 script. If it is done in the <prgn>postinst</prgn>, it
1321 should be protected with a conditional so that
1322 unnecessary prompting doesn't happen if a package's
1323 installation fails and the <prgn>postinst</prgn> is
1324 called with <tt>abort-upgrade</tt>,
1325 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1335 <heading>Source packages</heading>
1337 <sect id="standardsversion">
1338 <heading>Standards conformance</heading>
1341 Source packages should specify the most recent version number
1342 of this policy document with which your package complied
1343 when it was last updated.
1347 This information may be used to file bug reports
1348 automatically if your package becomes too much out of date.
1352 The version is specified in the <tt>Standards-Version</tt>
1354 The format of the <tt>Standards-Version</tt> field is
1355 described in <ref id="f-Standards-Version">.
1359 You should regularly, and especially if your package has
1360 become out of date, check for the newest Policy Manual
1361 available and update your package, if necessary. When your
1362 package complies with the new standards you should update the
1363 <tt>Standards-Version</tt> source package field and
1364 release it.<footnote>
1365 See the file <file>upgrading-checklist</file> for
1366 information about policy which has changed between
1367 different versions of this document.
1373 <sect id="pkg-relations">
1374 <heading>Package relationships</heading>
1377 Source packages should specify which binary packages they
1378 require to be installed or not to be installed in order to
1379 build correctly. For example, if building a package
1380 requires a certain compiler, then the compiler should be
1381 specified as a build-time dependency.
1385 It is not necessary to explicitly specify build-time
1386 relationships on a minimal set of packages that are always
1387 needed to compile, link and put in a Debian package a
1388 standard "Hello World!" program written in C or C++. The
1389 required packages are called <em>build-essential</em>, and
1390 an informational list can be found in
1391 <file>/usr/share/doc/build-essential/list</file> (which is
1392 contained in the <tt>build-essential</tt>
1395 <list compact="compact">
1397 This allows maintaining the list separately
1398 from the policy documents (the list does not
1399 need the kind of control that the policy
1403 Having a separate package allows one to install
1404 the build-essential packages on a machine, as
1405 well as allowing other packages such as tasks to
1406 require installation of the build-essential
1407 packages using the depends relation.
1410 The separate package allows bug reports against
1411 the list to be categorized separately from
1412 the policy management process in the BTS.
1419 When specifying the set of build-time dependencies, one
1420 should list only those packages explicitly required by the
1421 build. It is not necessary to list packages which are
1422 required merely because some other package in the list of
1423 build-time dependencies depends on them.<footnote>
1424 The reason for this is that dependencies change, and
1425 you should list all those packages, and <em>only</em>
1426 those packages that <em>you</em> need directly. What
1427 others need is their business. For example, if you
1428 only link against <file>libimlib</file>, you will need to
1429 build-depend on <package>libimlib2-dev</package> but
1430 not against any <tt>libjpeg*</tt> packages, even
1431 though <tt>libimlib2-dev</tt> currently depends on
1432 them: installation of <package>libimlib2-dev</package>
1433 will automatically ensure that all of its run-time
1434 dependencies are satisfied.
1439 If build-time dependencies are specified, it must be
1440 possible to build the package and produce working binaries
1441 on a system with only essential and build-essential
1442 packages installed and also those required to satisfy the
1443 build-time relationships (including any implied
1444 relationships). In particular, this means that version
1445 clauses should be used rigorously in build-time
1446 relationships so that one cannot produce bad or
1447 inconsistently configured packages when the relationships
1448 are properly satisfied.
1452 <ref id="relationships"> explains the technical details.
1457 <heading>Changes to the upstream sources</heading>
1460 If changes to the source code are made that are not
1461 specific to the needs of the Debian system, they should be
1462 sent to the upstream authors in whatever form they prefer
1463 so as to be included in the upstream version of the
1468 If you need to configure the package differently for
1469 Debian or for Linux, and the upstream source doesn't
1470 provide a way to do so, you should add such configuration
1471 facilities (for example, a new <prgn>autoconf</prgn> test
1472 or <tt>#define</tt>) and send the patch to the upstream
1473 authors, with the default set to the way they originally
1474 had it. You can then easily override the default in your
1475 <file>debian/rules</file> or wherever is appropriate.
1479 You should make sure that the <prgn>configure</prgn> utility
1480 detects the correct architecture specification string
1481 (refer to <ref id="arch-spec"> for details).
1485 If you need to edit a <prgn>Makefile</prgn> where GNU-style
1486 <prgn>configure</prgn> scripts are used, you should edit the
1487 <file>.in</file> files rather than editing the
1488 <prgn>Makefile</prgn> directly. This allows the user to
1489 reconfigure the package if necessary. You should
1490 <em>not</em> configure the package and edit the generated
1491 <prgn>Makefile</prgn>! This makes it impossible for someone
1492 else to later reconfigure the package without losing the
1498 <sect id="dpkgchangelog">
1499 <heading>Debian changelog: <file>debian/changelog</file></heading>
1502 Changes in the Debian version of the package should be
1503 briefly explained in the Debian changelog file
1504 <file>debian/changelog</file>.<footnote>
1506 Mistakes in changelogs are usually best rectified by
1507 making a new changelog entry rather than "rewriting
1508 history" by editing old changelog entries.
1511 This includes modifications
1512 made in the Debian package compared to the upstream one
1513 as well as other changes and updates to the package.
1515 Although there is nothing stopping an author who is also
1516 the Debian maintainer from using this changelog for all
1517 their changes, it will have to be renamed if the Debian
1518 and upstream maintainers become different people. In such
1519 a case, however, it might be better to maintain the package
1520 as a non-native package.
1525 The format of the <file>debian/changelog</file> allows the
1526 package building tools to discover which version of the package
1527 is being built and find out other release-specific information.
1531 That format is a series of entries like this:
1533 <example compact="compact">
1534 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1536 [optional blank line(s), stripped]
1538 * <var>change details</var>
1539 <var>more change details</var>
1541 [blank line(s), included in output of dpkg-parsechangelog]
1543 * <var>even more change details</var>
1545 [optional blank line(s), stripped]
1547 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1552 <var>package</var> and <var>version</var> are the source
1553 package name and version number.
1557 <var>distribution(s)</var> lists the distributions where
1558 this version should be installed when it is uploaded - it
1559 is copied to the <tt>Distribution</tt> field in the
1560 <file>.changes</file> file. See <ref id="f-Distribution">.
1564 <var>urgency</var> is the value for the <tt>Urgency</tt>
1565 field in the <file>.changes</file> file for the upload
1566 (see <ref id="f-Urgency">). It is not possible to specify
1567 an urgency containing commas; commas are used to separate
1568 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1569 <prgn>dpkg</prgn> changelog format (though there is
1570 currently only one useful <var>keyword</var>,
1575 The change details may in fact be any series of lines
1576 starting with at least two spaces, but conventionally each
1577 change starts with an asterisk and a separating space and
1578 continuation lines are indented so as to bring them in
1579 line with the start of the text above. Blank lines may be
1580 used here to separate groups of changes, if desired.
1584 If this upload resolves bugs recorded in the Bug Tracking
1585 System (BTS), they may be automatically closed on the
1586 inclusion of this package into the Debian archive by
1587 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1588 in the change details.<footnote>
1589 To be precise, the string should match the following
1590 Perl regular expression:
1592 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1594 Then all of the bug numbers listed will be closed by the
1595 archive maintenance script (<prgn>katie</prgn>) using the
1596 <var>version</var> of the changelog entry.
1598 This information is conveyed via the <tt>Closes</tt> field
1599 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1603 The maintainer name and email address used in the changelog
1604 should be the details of the person uploading <em>this</em>
1605 version. They are <em>not</em> necessarily those of the
1606 usual package maintainer. The information here will be
1607 copied to the <tt>Changed-By</tt> field in the
1608 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1609 and then later used to send an acknowledgement when the
1610 upload has been installed.
1614 The <var>date</var> must be in RFC822 format<footnote>
1615 This is generated by <tt>date -R</tt>.
1616 </footnote>; it must include the time zone specified
1617 numerically, with the time zone name or abbreviation
1618 optionally present as a comment in parentheses.
1622 The first "title" line with the package name must start
1623 at the left hand margin. The "trailer" line with the
1624 maintainer and date details must be preceded by exactly
1625 one space. The maintainer details and the date must be
1626 separated by exactly two spaces.
1630 The entire changelog must be encoded in UTF-8.
1634 For more information on placement of the changelog files
1635 within binary packages, please see <ref id="changelogs">.
1639 <sect id="dpkgcopyright">
1640 <heading>Copyright: <file>debian/copyright</file></heading>
1642 Every package must be accompanied by a verbatim copy of
1643 its copyright and distribution license in the file
1644 <file>/usr/share/doc/<var>package</var>/copyright</file>
1645 (see <ref id="copyrightfile"> for further details). Also see
1646 <ref id="pkgcopyright"> for further considerations related
1647 to copyrights for packages.
1651 <heading>Error trapping in makefiles</heading>
1654 When <prgn>make</prgn> invokes a command in a makefile
1655 (including your package's upstream makefiles and
1656 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1657 means that <prgn>sh</prgn>'s usual bad error handling
1658 properties apply: if you include a miniature script as one
1659 of the commands in your makefile you'll find that if you
1660 don't do anything about it then errors are not detected
1661 and <prgn>make</prgn> will blithely continue after
1666 Every time you put more than one shell command (this
1667 includes using a loop) in a makefile command you
1668 must make sure that errors are trapped. For
1669 simple compound commands, such as changing directory and
1670 then running a program, using <tt>&&</tt> rather
1671 than semicolon as a command separator is sufficient. For
1672 more complex commands including most loops and
1673 conditionals you should include a separate <tt>set -e</tt>
1674 command at the start of every makefile command that's
1675 actually one of these miniature shell scripts.
1679 <sect id="timestamps">
1680 <heading>Time Stamps</heading>
1682 Maintainers should preserve the modification times of the
1683 upstream source files in a package, as far as is reasonably
1685 The rationale is that there is some information conveyed
1686 by knowing the age of the file, for example, you could
1687 recognize that some documentation is very old by looking
1688 at the modification time, so it would be nice if the
1689 modification time of the upstream source would be
1695 <sect id="restrictions">
1696 <heading>Restrictions on objects in source packages</heading>
1699 The source package may not contain any hard links<footnote>
1701 This is not currently detected when building source
1702 packages, but only when extracting
1706 Hard links may be permitted at some point in the
1707 future, but would require a fair amount of
1710 </footnote>, device special files, sockets or setuid or
1711 setgid files.<footnote>
1712 Setgid directories are allowed.
1717 <sect id="debianrules">
1718 <heading>Main building script: <file>debian/rules</file></heading>
1721 This file must be an executable makefile, and contains the
1722 package-specific recipes for compiling the package and
1723 building binary package(s) from the source.
1727 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1728 so that it can be invoked by saying its name rather than
1729 invoking <prgn>make</prgn> explicitly.
1733 Since an interactive <file>debian/rules</file> script makes it
1734 impossible to auto-compile that package and also makes it
1735 hard for other people to reproduce the same binary
1736 package, all <em>required targets</em> MUST be
1737 non-interactive. At a minimum, required targets are the
1738 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1739 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1740 <em>binary-indep</em>, and <em>build</em>. It also follows
1741 that any target that these targets depend on must also be
1746 The targets are as follows (required unless stated otherwise):
1748 <tag><tt>build</tt></tag>
1751 The <tt>build</tt> target should perform all the
1752 configuration and compilation of the package.
1753 If a package has an interactive pre-build
1754 configuration routine, the Debianized source package
1755 must either be built after this has taken place (so
1756 that the binary package can be built without rerunning
1757 the configuration) or the configuration routine
1758 modified to become non-interactive. (The latter is
1759 preferable if there are architecture-specific features
1760 detected by the configuration routine.)
1764 For some packages, notably ones where the same
1765 source tree is compiled in different ways to produce
1766 two binary packages, the <tt>build</tt> target
1767 does not make much sense. For these packages it is
1768 good enough to provide two (or more) targets
1769 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1770 for each of the ways of building the package, and a
1771 <tt>build</tt> target that does nothing. The
1772 <tt>binary</tt> target will have to build the
1773 package in each of the possible ways and make the
1774 binary package out of each.
1778 The <tt>build</tt> target must not do anything
1779 that might require root privilege.
1783 The <tt>build</tt> target may need to run the
1784 <tt>clean</tt> target first - see below.
1788 When a package has a configuration and build routine
1789 which takes a long time, or when the makefiles are
1790 poorly designed, or when <tt>build</tt> needs to
1791 run <tt>clean</tt> first, it is a good idea to
1792 <tt>touch build</tt> when the build process is
1793 complete. This will ensure that if <tt>debian/rules
1794 build</tt> is run again it will not rebuild the whole
1796 Another common way to do this is for <tt>build</tt>
1797 to depend on <prgn>build-stamp</prgn> and to do
1798 nothing else, and for the <prgn>build-stamp</prgn>
1799 target to do the building and to <tt>touch
1800 build-stamp</tt> on completion. This is
1801 especially useful if the build routine creates a
1802 file or directory called <tt>build</tt>; in such a
1803 case, <tt>build</tt> will need to be listed as
1804 a phony target (i.e., as a dependency of the
1805 <tt>.PHONY</tt> target). See the documentation of
1806 <prgn>make</prgn> for more information on phony
1812 <tag><tt>build-arch</tt> (optional),
1813 <tt>build-indep</tt> (optional)
1817 A package may also provide both of the targets
1818 <tt>build-arch</tt> and <tt>build-indep</tt>.
1819 The <tt>build-arch</tt> target, if provided, should
1820 perform all the configuration and compilation required
1821 for producing all architecture-dependant binary packages
1822 (those packages for which the body of the
1823 <tt>Architecture</tt> field in <tt>debian/control</tt>
1824 is not <tt>all</tt>).
1825 Similarly, the <tt>build-indep</tt> target, if
1826 provided, should perform all the configuration and
1827 compilation required for producing all
1828 architecture-independent binary packages
1829 (those packages for which the body of the
1830 <tt>Architecture</tt> field in <tt>debian/control</tt>
1832 The <tt>build</tt> target should depend on those of the
1833 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1834 are provided in the rules file.
1838 If one or both of the targets <tt>build-arch</tt> and
1839 <tt>build-indep</tt> are not provided, then invoking
1840 <file>debian/rules</file> with one of the not-provided
1841 targets as arguments should produce a exit status code
1842 of 2. Usually this is provided automatically by make
1843 if the target is missing.
1847 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1848 must not do anything that might require root privilege.
1852 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1853 <tt>binary-indep</tt>
1857 The <tt>binary</tt> target must be all that is
1858 necessary for the user to build the binary package(s)
1859 produced from this source package. It is
1860 split into two parts: <prgn>binary-arch</prgn> builds
1861 the binary packages which are specific to a particular
1862 architecture, and <tt>binary-indep</tt> builds
1863 those which are not.
1866 <tt>binary</tt> may be (and commonly is) a target with
1867 no commands which simply depends on
1868 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1871 Both <tt>binary-*</tt> targets should depend on the
1872 <tt>build</tt> target, or on the appropriate
1873 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1874 provided, so that the package is built if it has not
1875 been already. It should then create the relevant
1876 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1877 make their control files and <prgn>dpkg-deb</prgn> to
1878 build them and place them in the parent of the top
1883 Both the <tt>binary-arch</tt> and
1884 <tt>binary-indep</tt> targets <em>must</em> exist.
1885 If one of them has nothing to do (which will always be
1886 the case if the source generates only a single binary
1887 package, whether architecture-dependent or not), it
1888 must still exist and must always succeed.
1892 The <tt>binary</tt> targets must be invoked as
1894 The <prgn>fakeroot</prgn> package often allows one
1895 to build a package correctly even without being
1901 <tag><tt>clean</tt></tag>
1904 This must undo any effects that the <tt>build</tt>
1905 and <tt>binary</tt> targets may have had, except
1906 that it should leave alone any output files created in
1907 the parent directory by a run of a <tt>binary</tt>
1912 If a <tt>build</tt> file is touched at the end of
1913 the <tt>build</tt> target, as suggested above, it
1914 should be removed as the first action that
1915 <tt>clean</tt> performs, so that running
1916 <tt>build</tt> again after an interrupted
1917 <tt>clean</tt> doesn't think that everything is
1922 The <tt>clean</tt> target may need to be
1923 invoked as root if <tt>binary</tt> has been
1924 invoked since the last <tt>clean</tt>, or if
1925 <tt>build</tt> has been invoked as root (since
1926 <tt>build</tt> may create directories, for
1931 <tag><tt>get-orig-source</tt> (optional)</tag>
1934 This target fetches the most recent version of the
1935 original source package from a canonical archive site
1936 (via FTP or WWW, for example), does any necessary
1937 rearrangement to turn it into the original source
1938 tar file format described below, and leaves it in the
1943 This target may be invoked in any directory, and
1944 should take care to clean up any temporary files it
1949 This target is optional, but providing it if
1950 possible is a good idea.
1954 <tag><tt>patch</tt> (optional)</tag>
1957 This target performs whatever additional actions are
1958 required to make the source ready for editing (unpacking
1959 additional upstream archives, applying patches, etc.).
1960 It is recommended to be implemented for any package where
1961 <tt>dpkg-source -x</tt> does not result in source ready
1962 for additional modification. See
1963 <ref id="readmesource">.
1969 The <tt>build</tt>, <tt>binary</tt> and
1970 <tt>clean</tt> targets must be invoked with the current
1971 directory being the package's top-level directory.
1976 Additional targets may exist in <file>debian/rules</file>,
1977 either as published or undocumented interfaces or for the
1978 package's internal use.
1982 The architectures we build on and build for are determined
1983 by <prgn>make</prgn> variables using the utility
1984 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
1985 You can determine the
1986 Debian architecture and the GNU style architecture
1987 specification string for the build machine (the machine type
1988 we are building on) as well as for the host machine (the
1989 machine type we are building for). Here is a list of
1990 supported <prgn>make</prgn> variables:
1991 <list compact="compact">
1993 <tt>DEB_*_ARCH</tt> (the Debian architecture)
1996 <tt>DEB_*_ARCH_CPU</tt> (the Debian CPU name)
1999 <tt>DEB_*_ARCH_OS</tt> (the Debian System name)
2002 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2003 specification string)
2006 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2007 <tt>DEB_*_GNU_TYPE</tt>)
2010 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2011 <tt>DEB_*_GNU_TYPE</tt>)
2013 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2014 the build machine or <tt>HOST</tt> for specification of the
2019 Backward compatibility can be provided in the rules file
2020 by setting the needed variables to suitable default
2021 values; please refer to the documentation of
2022 <prgn>dpkg-architecture</prgn> for details.
2026 It is important to understand that the <tt>DEB_*_ARCH</tt>
2027 string only determines which Debian architecture we are
2028 building on or for. It should not be used to get the CPU
2029 or system information; the <tt>DEB_*_ARCH_CPU</tt> and
2030 <tt>DEB_*_ARCH_OS</tt> variables should be used for that.
2031 GNU style variables should generally only be used with upstream
2035 <sect1 id="debianrules-options">
2036 <heading><file>debian/rules</file> and
2037 <tt>DEB_BUILD_OPTIONS</tt></heading>
2040 Supporting the standardized environment variable
2041 <tt>DEB_BUILD_OPTIONS</tt> is recommended. This variable can
2042 contain several flags to change how a package is compiled and
2043 built. Each flag must be in the form <var>flag</var> or
2044 <var>flag</var>=<var>options</var>. If multiple flags are
2045 given, they must be separated by whitespace.<footnote>
2046 Some packages support any delimiter, but whitespace is the
2047 easiest to parse inside a makefile and avoids ambiguity with
2048 flag values that contain commas.
2050 <var>flag</var> must start with a lowercase letter
2051 (<tt>a-z</tt>) and consist only of lowercase letters,
2052 numbers (<tt>0-9</tt>), and the characters
2053 <tt>-</tt> and <tt>_</tt> (hyphen and underscore).
2054 <var>options</var> must not contain whitespace. The same
2055 tag should not be given multiple times with conflicting
2056 values. Package maintainers may assume that
2057 <tt>DEB_BUILD_OPTIONS</tt> will not contain conflicting tags.
2061 The meaning of the following tags has been standardized:
2065 This tag says to not run any build-time test suite
2066 provided by the package.
2070 The presence of this tag means that the package should
2071 be compiled with a minimum of optimization. For C
2072 programs, it is best to add <tt>-O0</tt> to
2073 <tt>CFLAGS</tt> (although this is usually the default).
2074 Some programs might fail to build or run at this level
2075 of optimization; it may be necessary to use
2076 <tt>-O1</tt>, for example.
2080 This tag means that the debugging symbols should not be
2081 stripped from the binary during installation, so that
2082 debugging information may be included in the package.
2084 <tag>parallel=n</tag>
2086 This tag means that the package should be built using up
2087 to <tt>n</tt> parallel processes if the package build
2088 system supports this.<footnote>
2089 Packages built with <tt>make</tt> can often implement
2090 this by passing the <tt>-j</tt><var>n</var> option to
2093 If the package build system does not support parallel
2094 builds, this string must be ignored. If the package
2095 build system only supports a lower level of concurrency
2096 than <var>n</var>, the package should be built using as
2097 many parallel processes as the package build system
2098 supports. It is up to the package maintainer to decide
2099 whether the package build times are long enough and the
2100 package build system is robust enough to make supporting
2101 parallel builds worthwhile.
2107 Unknown flags must be ignored by <file>debian/rules</file>.
2111 The following makefile snippet is an example of how one may
2112 implement the build options; you will probably have to
2113 massage this example in order to make it work for your
2115 <example compact="compact">
2118 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
2119 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
2120 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
2121 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
2123 ifneq (,$(filter noopt,$(DEB_BUILD_OPTIONS)))
2128 ifeq (,$(filter nostrip,$(DEB_BUILD_OPTIONS)))
2129 INSTALL_PROGRAM += -s
2131 ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2132 NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2133 MAKEFLAGS += -j$(NUMJOBS)
2138 ifeq (,$(filter nocheck,$(DEB_BUILD_OPTIONS)))
2139 # Code to run the package test suite.
2146 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2147 <sect id="substvars">
2148 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2151 When <prgn>dpkg-gencontrol</prgn>,
2152 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2153 generate control files they perform variable substitutions
2154 on their output just before writing it. Variable
2155 substitutions have the form <tt>${<var>variable</var>}</tt>.
2156 The optional file <file>debian/substvars</file> contains
2157 variable substitutions to be used; variables can also be set
2158 directly from <file>debian/rules</file> using the <tt>-V</tt>
2159 option to the source packaging commands, and certain
2160 predefined variables are also available.
2164 The <file>debian/substvars</file> file is usually generated and
2165 modified dynamically by <file>debian/rules</file> targets, in
2166 which case it must be removed by the <tt>clean</tt> target.
2170 See <manref name="deb-substvars" section="5"> for full
2171 details about source variable substitutions, including the
2172 format of <file>debian/substvars</file>.</p>
2175 <sect id="debianwatch">
2176 <heading>Optional upstream source location: <file>debian/watch</file></heading>
2179 This is an optional, recommended control file for the
2180 <tt>uscan</tt> utility which defines how to automatically
2181 scan ftp or http sites for newly available updates of the
2182 package. This is used by <url id="
2183 http://dehs.alioth.debian.org/"> and other Debian QA tools
2184 to help with quality control and maintenance of the
2185 distribution as a whole.
2190 <sect id="debianfiles">
2191 <heading>Generated files list: <file>debian/files</file></heading>
2194 This file is not a permanent part of the source tree; it
2195 is used while building packages to record which files are
2196 being generated. <prgn>dpkg-genchanges</prgn> uses it
2197 when it generates a <file>.changes</file> file.
2201 It should not exist in a shipped source package, and so it
2202 (and any backup files or temporary files such as
2203 <file>files.new</file><footnote>
2204 <file>files.new</file> is used as a temporary file by
2205 <prgn>dpkg-gencontrol</prgn> and
2206 <prgn>dpkg-distaddfile</prgn> - they write a new
2207 version of <tt>files</tt> here before renaming it,
2208 to avoid leaving a corrupted copy if an error
2210 </footnote>) should be removed by the
2211 <tt>clean</tt> target. It may also be wise to
2212 ensure a fresh start by emptying or removing it at the
2213 start of the <tt>binary</tt> target.
2217 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2218 package, it adds an entry to <file>debian/files</file> for the
2219 <file>.deb</file> file that will be created when <tt>dpkg-deb
2220 --build</tt> is run for that binary package. So for most
2221 packages all that needs to be done with this file is to
2222 delete it in the <tt>clean</tt> target.
2226 If a package upload includes files besides the source
2227 package and any binary packages whose control files were
2228 made with <prgn>dpkg-gencontrol</prgn> then they should be
2229 placed in the parent of the package's top-level directory
2230 and <prgn>dpkg-distaddfile</prgn> should be called to add
2231 the file to the list in <file>debian/files</file>.</p>
2234 <sect id="embeddedfiles">
2235 <heading>Convenience copies of code</heading>
2238 Some software packages include in their distribution convenience
2239 copies of code from other software packages, generally so that
2240 users compiling from source don't have to download multiple
2241 packages. Debian packages should not make use of these
2242 convenience copies unless the included package is explicitly
2243 intended to be used in this way.<footnote>
2244 For example, parts of the GNU build system work like this.
2246 If the included code is already in the Debian archive in the
2247 form of a library, the Debian packaging should ensure that
2248 binary packages reference the libraries already in Debian and
2249 the convenience copy is not used. If the included code is not
2250 already in Debian, it should be packaged separately as a
2251 prerequisite if possible.
2253 Having multiple copies of the same code in Debian is
2254 inefficient, often creates either static linking or shared
2255 library conflicts, and, most importantly, increases the
2256 difficulty of handling security vulnerabilities in the
2262 <sect id="readmesource">
2263 <heading>Source package handling:
2264 <file>debian/README.source</file></heading>
2267 If running <prgn>dpkg-source -x</prgn> on a source package
2268 doesn't produce the source of the package, ready for editing,
2269 and allow one to make changes and run
2270 <prgn>dpkg-buildpackage</prgn> to produce a modified package
2271 without taking any additional steps, creating a
2272 <file>debian/README.source</file> documentation file is
2273 recommended. This file should explain how to do all of the
2276 <item>Generate the fully patched source, in a form ready for
2277 editing, that would be built to create Debian
2278 packages. Doing this with a <tt>patch</tt> target in
2279 <file>debian/rules</file> is recommended; see
2280 <ref id="debianrules">.</item>
2281 <item>Modify the source and save those modifications so that
2282 they will be applied when building the package.</item>
2283 <item>Remove source modifications that are currently being
2284 applied when building the package.</item>
2285 <item>Optionally, document what steps are necessary to
2286 upgrade the Debian source package to a new upstream version,
2287 if applicable.</item>
2289 This explanation should include specific commands and mention
2290 any additional required Debian packages. It should not assume
2291 familiarity with any specific Debian packaging system or patch
2296 This explanation may refer to a documentation file installed by
2297 one of the package's build dependencies provided that the
2298 referenced documentation clearly explains these tasks and is not
2299 a general reference manual.
2303 <file>debian/README.source</file> may also include any other
2304 information that would be helpful to someone modifying the
2305 source package. Even if the package doesn't fit the above
2306 description, maintainers are encouraged to document in a
2307 <file>debian/README.source</file> file any source package with a
2308 particularly complex or unintuitive source layout or build
2309 system (for example, a package that builds the same source
2310 multiple times to generate different binary packages).
2316 <chapt id="controlfields">
2317 <heading>Control files and their fields</heading>
2320 The package management system manipulates data represented in
2321 a common format, known as <em>control data</em>, stored in
2322 <em>control files</em>.
2323 Control files are used for source packages, binary packages and
2324 the <file>.changes</file> files which control the installation
2325 of uploaded files<footnote>
2326 <prgn>dpkg</prgn>'s internal databases are in a similar
2331 <sect id="controlsyntax">
2332 <heading>Syntax of control files</heading>
2335 A control file consists of one or more paragraphs of
2337 The paragraphs are also sometimes referred to as stanzas.
2339 The paragraphs are separated by blank lines. Some control
2340 files allow only one paragraph; others allow several, in
2341 which case each paragraph usually refers to a different
2342 package. (For example, in source packages, the first
2343 paragraph refers to the source package, and later paragraphs
2344 refer to binary packages generated from the source.)
2348 Each paragraph consists of a series of data fields; each
2349 field consists of the field name, followed by a colon and
2350 then the data/value associated with that field. It ends at
2351 the end of the (logical) line. Horizontal whitespace
2352 (spaces and tabs) may occur immediately before or after the
2353 value and is ignored there; it is conventional to put a
2354 single space after the colon. For example, a field might
2356 <example compact="compact">
2359 the field name is <tt>Package</tt> and the field value
2364 Many fields' values may span several lines; in this case
2365 each continuation line must start with a space or a tab.
2366 Any trailing spaces or tabs at the end of individual
2367 lines of a field value are ignored.
2371 In fields where it is specified that lines may not wrap,
2372 only a single line of data is allowed and whitespace is not
2373 significant in a field body. Whitespace must not appear
2374 inside names (of packages, architectures, files or anything
2375 else) or version numbers, or between the characters of
2376 multi-character version relationships.
2380 Field names are not case-sensitive, but it is usual to
2381 capitalize the field names using mixed case as shown below.
2382 Field values are case-sensitive unless the description of the
2383 field says otherwise.
2387 Blank lines, or lines consisting only of spaces and tabs,
2388 are not allowed within field values or between fields - that
2389 would mean a new paragraph.
2393 All control files must be encoded in UTF-8.
2397 <sect id="sourcecontrolfiles">
2398 <heading>Source package control files -- <file>debian/control</file></heading>
2401 The <file>debian/control</file> file contains the most vital
2402 (and version-independent) information about the source package
2403 and about the binary packages it creates.
2407 The first paragraph of the control file contains information about
2408 the source package in general. The subsequent sets each describe a
2409 binary package that the source tree builds.
2413 The fields in the general paragraph (the first one, for the source
2416 <list compact="compact">
2417 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2418 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2419 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2420 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2421 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2422 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2423 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2424 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2429 The fields in the binary package paragraphs are:
2431 <list compact="compact">
2432 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2433 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2434 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2435 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2436 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2437 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2438 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2439 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2444 The syntax and semantics of the fields are described below.
2450 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2451 generate control files for binary packages (see below), by
2452 <prgn>dpkg-genchanges</prgn> to generate the
2453 <tt>.changes</tt> file to accompany the upload, and by
2454 <prgn>dpkg-source</prgn> when it creates the
2455 <file>.dsc</file> source control file as part of a source
2456 archive. Many fields are permitted to span multiple lines in
2457 <file>debian/control</file> but not in any other control
2458 file. These tools are responsible for removing the line
2459 breaks from such fields when using fields from
2460 <file>debian/control</file> to generate other control files.
2464 The fields here may contain variable references - their
2465 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2466 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2467 when they generate output control files.
2468 See <ref id="substvars"> for details.
2472 In addition to the control file syntax described <qref
2473 id="controlsyntax">above</qref>, this file may also contain
2474 comment lines starting with <tt>#</tt> without any preceding
2475 whitespace. All such lines are ignored, even in the middle of
2476 continuation lines for a multiline field, and do not end a
2482 <sect id="binarycontrolfiles">
2483 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2486 The <file>DEBIAN/control</file> file contains the most vital
2487 (and version-dependent) information about a binary package.
2491 The fields in this file are:
2493 <list compact="compact">
2494 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2495 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2496 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2497 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2498 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2499 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2500 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2501 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2502 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2503 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2504 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2505 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2510 <sect id="debiansourcecontrolfiles">
2511 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2514 This file contains a series of fields, identified and
2515 separated just like the fields in the control file of
2516 a binary package. The fields are listed below; their
2517 syntax is described above, in <ref id="pkg-controlfields">.
2519 <list compact="compact">
2520 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2521 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2522 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2523 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2524 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2525 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2526 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2527 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2528 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2529 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2530 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2535 The source package control file is generated by
2536 <prgn>dpkg-source</prgn> when it builds the source
2537 archive, from other files in the source package,
2538 described above. When unpacking, it is checked against
2539 the files and directories in the other parts of the
2545 <sect id="debianchangesfiles">
2546 <heading>Debian changes files -- <file>.changes</file></heading>
2549 The .changes files are used by the Debian archive maintenance
2550 software to process updates to packages. They contain one
2551 paragraph which contains information from the
2552 <tt>debian/control</tt> file and other data about the
2553 source package gathered via <tt>debian/changelog</tt>
2554 and <tt>debian/rules</tt>.
2558 The fields in this file are:
2560 <list compact="compact">
2561 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2562 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2563 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2564 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2565 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2566 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2567 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2568 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2569 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2570 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2571 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2572 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2573 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2574 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2579 <sect id="controlfieldslist">
2580 <heading>List of fields</heading>
2582 <sect1 id="f-Source">
2583 <heading><tt>Source</tt></heading>
2586 This field identifies the source package name.
2590 In <file>debian/control</file> or a <file>.dsc</file> file,
2591 this field must contain only the name of the source package.
2595 In a binary package control file or a <file>.changes</file>
2596 file, the source package name may be followed by a version
2597 number in parentheses<footnote>
2598 It is customary to leave a space after the package name
2599 if a version number is specified.
2601 This version number may be omitted (and is, by
2602 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2603 the <tt>Version</tt> field of the binary package in
2604 question. The field itself may be omitted from a binary
2605 package control file when the source package has the same
2606 name and version as the binary package.
2610 Package names (both source and binary,
2611 see <ref id="f-Package">) must consist only of lower case
2612 letters (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus
2613 (<tt>+</tt>) and minus (<tt>-</tt>) signs, and periods
2614 (<tt>.</tt>). They must be at least two characters long and
2615 must start with an alphanumeric character.
2619 <sect1 id="f-Maintainer">
2620 <heading><tt>Maintainer</tt></heading>
2623 The package maintainer's name and email address. The name
2624 should come first, then the email address inside angle
2625 brackets <tt><></tt> (in RFC822 format).
2629 If the maintainer's name contains a full stop then the
2630 whole field will not work directly as an email address due
2631 to a misfeature in the syntax specified in RFC822; a
2632 program using this field as an address must check for this
2633 and correct the problem if necessary (for example by
2634 putting the name in round brackets and moving it to the
2635 end, and bringing the email address forward).
2639 <sect1 id="f-Uploaders">
2640 <heading><tt>Uploaders</tt></heading>
2643 List of the names and email addresses of co-maintainers of
2644 the package, if any. If the package has other maintainers
2645 beside the one named in the
2646 <qref id="f-Maintainer">Maintainer field</qref>, their
2647 names and email addresses should be listed here. The
2648 format is the same as that of the Maintainer tag, and
2649 multiple entries should be comma separated. Currently,
2650 this field is restricted to a single line of data. This
2651 is an optional field.
2654 Any parser that interprets the Uploaders field in
2655 <file>debian/control</file> must permit it to span multiple
2656 lines. Line breaks in an Uploaders field that spans multiple
2657 lines are not significant and the semantics of the field are
2658 the same as if the line breaks had not been present.
2662 <sect1 id="f-Changed-By">
2663 <heading><tt>Changed-By</tt></heading>
2666 The name and email address of the person who changed the
2667 said package. Usually the name of the maintainer.
2668 All the rules for the Maintainer field apply here, too.
2672 <sect1 id="f-Section">
2673 <heading><tt>Section</tt></heading>
2676 This field specifies an application area into which the package
2677 has been classified. See <ref id="subsections">.
2681 When it appears in the <file>debian/control</file> file,
2682 it gives the value for the subfield of the same name in
2683 the <tt>Files</tt> field of the <file>.changes</file> file.
2684 It also gives the default for the same field in the binary
2689 <sect1 id="f-Priority">
2690 <heading><tt>Priority</tt></heading>
2693 This field represents how important that it is that the user
2694 have the package installed. See <ref id="priorities">.
2698 When it appears in the <file>debian/control</file> file,
2699 it gives the value for the subfield of the same name in
2700 the <tt>Files</tt> field of the <file>.changes</file> file.
2701 It also gives the default for the same field in the binary
2706 <sect1 id="f-Package">
2707 <heading><tt>Package</tt></heading>
2710 The name of the binary package.
2714 Binary package names must follow the same syntax and
2715 restrictions as source package names. See <ref id="f-Source">
2720 <sect1 id="f-Architecture">
2721 <heading><tt>Architecture</tt></heading>
2724 Depending on context and the control file used, the
2725 <tt>Architecture</tt> field can include the following sets of
2728 <item>A unique single word identifying a Debian machine
2729 architecture as described in <ref id="arch-spec">.
2730 <item><tt>all</tt>, which indicates an
2731 architecture-independent package.
2732 <item><tt>any</tt>, which indicates a package available
2733 for building on any architecture.
2734 <item><tt>source</tt>, which indicates a source package.
2739 In the main <file>debian/control</file> file in the source
2740 package, this field may contain the special value
2741 <tt>any</tt>, the special value <tt>all</tt>, or a list of
2742 architectures separated by spaces. If <tt>any</tt> or
2743 <tt>all</tt> appear, they must be the entire contents of the
2744 field. Most packages will use either <tt>any</tt> or
2745 <tt>all</tt>. Specifying a specific list of architectures is
2746 for the minority of cases where a program is not portable or
2747 is not useful on some architectures, and where possible the
2748 program should be made portable instead.
2752 In the source package control file <file>.dsc</file>, this
2753 field may contain either the special value <tt>any</tt> or a
2754 list of architectures separated by spaces. If a list is given,
2755 it may include (or consist solely of) the special value
2756 <tt>all</tt>. In other words, in <file>.dsc</file> files
2757 unlike the <file>debian/control</file>, <tt>all</tt> may occur
2758 in combination with specific architectures. The
2759 <tt>Architecture</tt> field in the source package control file
2760 <file>.dsc</file> is generally constructed from the
2761 <tt>Architecture</tt> fields in the
2762 <file>debian/control</file> in the source package.
2766 Specifying <tt>any</tt> indicates that the source package
2767 isn't dependent on any particular architecture and should
2768 compile fine on any one. The produced binary package(s)
2769 will either be specific to whatever the current build
2770 architecture is or will be architecture-independent.
2774 Specifying only <tt>all</tt> indicates that the source package
2775 will only build architecture-independent packages. If this is
2776 the case, <tt>all</tt> must be used rather than <tt>any</tt>;
2777 <tt>any</tt> implies that the source package will build at
2778 least one architecture-dependent package.
2782 Specifying a list of architectures indicates that the source
2783 will build an architecture-dependent package, and will only
2784 work correctly on the listed architectures. If the source
2785 package also builds at least one architecture-independent
2786 package, <tt>all</tt> will also be included in the list.
2790 In a <file>.changes</file> file, the <tt>Architecture</tt>
2791 field lists the architecture(s) of the package(s)
2792 currently being uploaded. This will be a list; if the
2793 source for the package is also being uploaded, the special
2794 entry <tt>source</tt> is also present. <tt>all</tt> will be
2795 present if any architecture-independent packages are being
2796 uploaded. <tt>any</tt> may never occur in the
2797 <tt>Architecture</tt> field in the <file>.changes</file>
2802 See <ref id="debianrules"> for information how to get the
2803 architecture for the build process.
2807 <sect1 id="f-Essential">
2808 <heading><tt>Essential</tt></heading>
2811 This is a boolean field which may occur only in the
2812 control file of a binary package or in a per-package fields
2813 paragraph of a main source control data file.
2817 If set to <tt>yes</tt> then the package management system
2818 will refuse to remove the package (upgrading and replacing
2819 it is still possible). The other possible value is <tt>no</tt>,
2820 which is the same as not having the field at all.
2825 <heading>Package interrelationship fields:
2826 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2827 <tt>Recommends</tt>, <tt>Suggests</tt>,
2828 <tt>Breaks</tt>, <tt>Conflicts</tt>,
2829 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2833 These fields describe the package's relationships with
2834 other packages. Their syntax and semantics are described
2835 in <ref id="relationships">.</p>
2838 <sect1 id="f-Standards-Version">
2839 <heading><tt>Standards-Version</tt></heading>
2842 The most recent version of the standards (the policy
2843 manual and associated texts) with which the package
2848 The version number has four components: major and minor
2849 version number and major and minor patch level. When the
2850 standards change in a way that requires every package to
2851 change the major number will be changed. Significant
2852 changes that will require work in many packages will be
2853 signaled by a change to the minor number. The major patch
2854 level will be changed for any change to the meaning of the
2855 standards, however small; the minor patch level will be
2856 changed when only cosmetic, typographical or other edits
2857 are made which neither change the meaning of the document
2858 nor affect the contents of packages.
2862 Thus only the first three components of the policy version
2863 are significant in the <em>Standards-Version</em> control
2864 field, and so either these three components or the all
2865 four components may be specified.<footnote>
2866 In the past, people specified the full version number
2867 in the Standards-Version field, for example "2.3.0.0".
2868 Since minor patch-level changes don't introduce new
2869 policy, it was thought it would be better to relax
2870 policy and only require the first 3 components to be
2871 specified, in this example "2.3.0". All four
2872 components may still be used if someone wishes to do so.
2878 <sect1 id="f-Version">
2879 <heading><tt>Version</tt></heading>
2882 The version number of a package. The format is:
2883 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2887 The three components here are:
2889 <tag><var>epoch</var></tag>
2892 This is a single (generally small) unsigned integer. It
2893 may be omitted, in which case zero is assumed. If it is
2894 omitted then the <var>upstream_version</var> may not
2899 It is provided to allow mistakes in the version numbers
2900 of older versions of a package, and also a package's
2901 previous version numbering schemes, to be left behind.
2905 <tag><var>upstream_version</var></tag>
2908 This is the main part of the version number. It is
2909 usually the version number of the original ("upstream")
2910 package from which the <file>.deb</file> file has been made,
2911 if this is applicable. Usually this will be in the same
2912 format as that specified by the upstream author(s);
2913 however, it may need to be reformatted to fit into the
2914 package management system's format and comparison
2919 The comparison behavior of the package management system
2920 with respect to the <var>upstream_version</var> is
2921 described below. The <var>upstream_version</var>
2922 portion of the version number is mandatory.
2926 The <var>upstream_version</var> may contain only
2927 alphanumerics<footnote>
2928 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2930 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2931 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
2932 tilde) and should start with a digit. If there is no
2933 <var>debian_revision</var> then hyphens are not allowed;
2934 if there is no <var>epoch</var> then colons are not
2939 <tag><var>debian_revision</var></tag>
2942 This part of the version number specifies the version of
2943 the Debian package based on the upstream version. It
2944 may contain only alphanumerics and the characters
2945 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
2946 tilde) and is compared in the same way as the
2947 <var>upstream_version</var> is.
2951 It is optional; if it isn't present then the
2952 <var>upstream_version</var> may not contain a hyphen.
2953 This format represents the case where a piece of
2954 software was written specifically to be turned into a
2955 Debian package, and so there is only one "debianisation"
2956 of it and therefore no revision indication is required.
2960 It is conventional to restart the
2961 <var>debian_revision</var> at <tt>1</tt> each time the
2962 <var>upstream_version</var> is increased.
2966 The package management system will break the version
2967 number apart at the last hyphen in the string (if there
2968 is one) to determine the <var>upstream_version</var> and
2969 <var>debian_revision</var>. The absence of a
2970 <var>debian_revision</var> is equivalent to a
2971 <var>debian_revision</var> of <tt>0</tt>.
2978 When comparing two version numbers, first the <var>epoch</var>
2979 of each are compared, then the <var>upstream_version</var> if
2980 <var>epoch</var> is equal, and then <var>debian_revision</var>
2981 if <var>upstream_version</var> is also equal.
2982 <var>epoch</var> is compared numerically. The
2983 <var>upstream_version</var> and <var>debian_revision</var>
2984 parts are compared by the package management system using the
2985 following algorithm:
2989 The strings are compared from left to right.
2993 First the initial part of each string consisting entirely of
2994 non-digit characters is determined. These two parts (one of
2995 which may be empty) are compared lexically. If a difference
2996 is found it is returned. The lexical comparison is a
2997 comparison of ASCII values modified so that all the letters
2998 sort earlier than all the non-letters and so that a tilde
2999 sorts before anything, even the end of a part. For example,
3000 the following parts are in sorted order from earliest to
3001 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
3002 <tt>a</tt>.<footnote>
3003 One common use of <tt>~</tt> is for upstream pre-releases.
3004 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
3005 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
3010 Then the initial part of the remainder of each string which
3011 consists entirely of digit characters is determined. The
3012 numerical values of these two parts are compared, and any
3013 difference found is returned as the result of the comparison.
3014 For these purposes an empty string (which can only occur at
3015 the end of one or both version strings being compared) counts
3020 These two steps (comparing and removing initial non-digit
3021 strings and initial digit strings) are repeated until a
3022 difference is found or both strings are exhausted.
3026 Note that the purpose of epochs is to allow us to leave behind
3027 mistakes in version numbering, and to cope with situations
3028 where the version numbering scheme changes. It is
3029 <em>not</em> intended to cope with version numbers containing
3030 strings of letters which the package management system cannot
3031 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
3032 silly orderings (the author of this manual has heard of a
3033 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
3034 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
3035 <tt>2</tt> and so forth).
3039 <sect1 id="f-Description">
3040 <heading><tt>Description</tt></heading>
3043 In a source or binary control file, the <tt>Description</tt>
3044 field contains a description of the binary package, consisting
3045 of two parts, the synopsis or the short description, and the
3046 long description. The field's format is as follows:
3051 Description: <single line synopsis>
3052 <extended description over several lines>
3057 The lines in the extended description can have these formats:
3063 Those starting with a single space are part of a paragraph.
3064 Successive lines of this form will be word-wrapped when
3065 displayed. The leading space will usually be stripped off.
3069 Those starting with two or more spaces. These will be
3070 displayed verbatim. If the display cannot be panned
3071 horizontally, the displaying program will line wrap them "hard"
3072 (i.e., without taking account of word breaks). If it can they
3073 will be allowed to trail off to the right. None, one or two
3074 initial spaces may be deleted, but the number of spaces
3075 deleted from each line will be the same (so that you can have
3076 indenting work correctly, for example).
3080 Those containing a single space followed by a single full stop
3081 character. These are rendered as blank lines. This is the
3082 <em>only</em> way to get a blank line<footnote>
3083 Completely empty lines will not be rendered as blank lines.
3084 Instead, they will cause the parser to think you're starting
3085 a whole new record in the control file, and will therefore
3086 likely abort with an error.
3091 Those containing a space, a full stop and some more characters.
3092 These are for future expansion. Do not use them.
3098 Do not use tab characters. Their effect is not predictable.
3102 See <ref id="descriptions"> for further information on this.
3106 In a <file>.changes</file> file, the <tt>Description</tt>
3107 field contains a summary of the descriptions for the packages
3108 being uploaded. For this case, the first line of the field
3109 value (the part on the same line as <tt>Description:</tt>) is
3110 always empty. The content of the field is expressed as
3111 continuation lines, one line per package. Each line is
3112 indented by one space and contains the name of a binary
3113 package, a space, a hyphen (<tt>-</tt>), a space, and the
3114 short description line from that package.
3118 <sect1 id="f-Distribution">
3119 <heading><tt>Distribution</tt></heading>
3122 In a <file>.changes</file> file or parsed changelog output
3123 this contains the (space-separated) name(s) of the
3124 distribution(s) where this version of the package should
3125 be installed. Valid distributions are determined by the
3126 archive maintainers.<footnote>
3127 Example distribution names in the Debian archive used in
3128 <file>.changes</file> files are:
3129 <taglist compact="compact">
3130 <tag><em>unstable</em></tag>
3132 This distribution value refers to the
3133 <em>developmental</em> part of the Debian distribution
3134 tree. Most new packages, new upstream versions of
3135 packages and bug fixes go into the <em>unstable</em>
3139 <tag><em>experimental</em></tag>
3141 The packages with this distribution value are deemed
3142 by their maintainers to be high risk. Oftentimes they
3143 represent early beta or developmental packages from
3144 various sources that the maintainers want people to
3145 try, but are not ready to be a part of the other parts
3146 of the Debian distribution tree.
3151 Others are used for updating stable releases or for
3152 security uploads. More information is available in the
3153 Debian Developer's Reference, section "The Debian
3157 The Debian archive software only supports listing a single
3158 distribution. Migration of packages to other distributions is
3159 handled outside of the upload process.
3164 <heading><tt>Date</tt></heading>
3167 This field includes the date the package was built or last edited.
3171 The value of this field is usually extracted from the
3172 <file>debian/changelog</file> file - see
3173 <ref id="dpkgchangelog">).
3177 <sect1 id="f-Format">
3178 <heading><tt>Format</tt></heading>
3181 This field specifies a format revision for the file.
3182 The most current format described in the Policy Manual
3183 is version <strong>1.5</strong>. The syntax of the
3184 format value is the same as that of a package version
3185 number except that no epoch or Debian revision is allowed
3186 - see <ref id="f-Version">.
3190 <sect1 id="f-Urgency">
3191 <heading><tt>Urgency</tt></heading>
3194 This is a description of how important it is to upgrade to
3195 this version from previous ones. It consists of a single
3196 keyword taking one of the values <tt>low</tt>,
3197 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3198 <tt>critical</tt><footnote>
3199 Other urgency values are supported with configuration
3200 changes in the archive software but are not used in Debian.
3201 The urgency affects how quickly a package will be considered
3202 for inclusion into the <tt>testing</tt> distribution and
3203 gives an indication of the importance of any fixes included
3204 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3205 treated as synonymous.
3206 </footnote> (not case-sensitive) followed by an optional
3207 commentary (separated by a space) which is usually in
3208 parentheses. For example:
3211 Urgency: low (HIGH for users of diversions)
3217 The value of this field is usually extracted from the
3218 <file>debian/changelog</file> file - see
3219 <ref id="dpkgchangelog">.
3223 <sect1 id="f-Changes">
3224 <heading><tt>Changes</tt></heading>
3227 This field contains the human-readable changes data, describing
3228 the differences between the last version and the current one.
3232 The first line of the field value (the part on the same line
3233 as <tt>Changes:</tt>) is always empty. The content of the
3234 field is expressed as continuation lines, with each line
3235 indented by at least one space. Blank lines must be
3236 represented by a line consisting only of a space and a full
3241 The value of this field is usually extracted from the
3242 <file>debian/changelog</file> file - see
3243 <ref id="dpkgchangelog">).
3247 Each version's change information should be preceded by a
3248 "title" line giving at least the version, distribution(s)
3249 and urgency, in a human-readable way.
3253 If data from several versions is being returned the entry
3254 for the most recent version should be returned first, and
3255 entries should be separated by the representation of a
3256 blank line (the "title" line may also be followed by the
3257 representation of blank line).
3261 <sect1 id="f-Binary">
3262 <heading><tt>Binary</tt></heading>
3265 This field is a list of binary packages. Its syntax and
3266 meaning varies depending on the control file in which it
3271 When it appears in the <file>.dsc</file> file, it lists binary
3272 packages which a source package can produce, separated by
3274 A space after each comma is conventional.
3275 </footnote>. It may span multiple lines. The source package
3276 does not necessarily produce all of these binary packages for
3277 every architecture. The source control file doesn't contain
3278 details of which architectures are appropriate for which of
3279 the binary packages.
3283 When it appears in a <file>.changes</file> file, it lists the
3284 names of the binary packages being uploaded, separated by
3285 whitespace (not commas). It may span multiple lines.
3289 <sect1 id="f-Installed-Size">
3290 <heading><tt>Installed-Size</tt></heading>
3293 This field appears in the control files of binary packages,
3294 and in the <file>Packages</file> files. It gives an estimate
3295 of the total amount of disk space required to install the
3296 named package. Actual installed size may vary based on block
3297 size, file system properties, or actions taken by package
3302 The disk space is given as the integer value of the estimated
3303 installed size in bytes, divided by 1024 and rounded up.
3307 <sect1 id="f-Files">
3308 <heading><tt>Files</tt></heading>
3311 This field contains a list of files with information about
3312 each one. The exact information and syntax varies with
3317 In all cases, Files is a multiline field. The first line of
3318 the field value (the part on the same line as <tt>Files:</tt>)
3319 is always empty. The content of the field is expressed as
3320 continuation lines, one line per file. Each line must be
3321 indented by one space and contain a number of sub-fields,
3322 separated by spaces, as described below.
3326 In the <file>.dsc</file> file, each line contains the MD5
3327 checksum, size and filename of the tar file and (if
3328 applicable) diff file which make up the remainder of the
3329 source package<footnote>
3330 That is, the parts which are not the <tt>.dsc</tt>.
3331 </footnote>. For example:
3334 c6f698f19f2a2aa07dbb9bbda90a2754 571925 example_1.2.orig.tar.gz
3335 938512f08422f3509ff36f125f5873ba 6220 example_1.2-1.diff.gz
3337 The exact forms of the filenames are described
3338 in <ref id="pkg-sourcearchives">.
3342 In the <file>.changes</file> file this contains one line per
3343 file being uploaded. Each line contains the MD5 checksum,
3344 size, section and priority and the filename. For example:
3347 4c31ab7bfc40d3cf49d7811987390357 1428 text extra example_1.2-1.dsc
3348 c6f698f19f2a2aa07dbb9bbda90a2754 571925 text extra example_1.2.orig.tar.gz
3349 938512f08422f3509ff36f125f5873ba 6220 text extra example_1.2-1.diff.gz
3350 7c98fe853b3bbb47a00e5cd129b6cb56 703542 text extra example_1.2-1_i386.deb
3352 The <qref id="f-Section">section</qref>
3353 and <qref id="f-Priority">priority</qref> are the values of
3354 the corresponding fields in the main source control file. If
3355 no section or priority is specified then <tt>-</tt> should be
3356 used, though section and priority values must be specified for
3357 new packages to be installed properly.
3361 The special value <tt>byhand</tt> for the section in a
3362 <tt>.changes</tt> file indicates that the file in question
3363 is not an ordinary package file and must by installed by
3364 hand by the distribution maintainers. If the section is
3365 <tt>byhand</tt> the priority should be <tt>-</tt>.
3369 If a new Debian revision of a package is being shipped and
3370 no new original source archive is being distributed the
3371 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3372 entry for the original source archive
3373 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
3374 but the <file>.changes</file> file should leave it out. In
3375 this case the original source archive on the distribution
3376 site must match exactly, byte-for-byte, the original
3377 source archive which was used to generate the
3378 <file>.dsc</file> file and diff which are being uploaded.</p>
3381 <sect1 id="f-Closes">
3382 <heading><tt>Closes</tt></heading>
3385 A space-separated list of bug report numbers that the upload
3386 governed by the .changes file closes.
3390 <sect1 id="f-Homepage">
3391 <heading><tt>Homepage</tt></heading>
3394 The URL of the web site for this package, preferably (when
3395 applicable) the site from which the original source can be
3396 obtained and any additional upstream documentation or
3397 information may be found. The content of this field is a
3398 simple URL without any surrounding characters such as
3406 <heading>User-defined fields</heading>
3409 Additional user-defined fields may be added to the
3410 source package control file. Such fields will be
3411 ignored, and not copied to (for example) binary or
3412 source package control files or upload control files.
3416 If you wish to add additional unsupported fields to
3417 these output files you should use the mechanism
3422 Fields in the main source control information file with
3423 names starting <tt>X</tt>, followed by one or more of
3424 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3425 be copied to the output files. Only the part of the
3426 field name after the hyphen will be used in the output
3427 file. Where the letter <tt>B</tt> is used the field
3428 will appear in binary package control files, where the
3429 letter <tt>S</tt> is used in source package control
3430 files and where <tt>C</tt> is used in upload control
3431 (<tt>.changes</tt>) files.
3435 For example, if the main source information control file
3438 XBS-Comment: I stand between the candle and the star.
3440 then the binary and source package control files will contain the
3443 Comment: I stand between the candle and the star.
3452 <chapt id="maintainerscripts">
3453 <heading>Package maintainer scripts and installation procedure</heading>
3456 <heading>Introduction to package maintainer scripts</heading>
3459 It is possible to supply scripts as part of a package which
3460 the package management system will run for you when your
3461 package is installed, upgraded or removed.
3465 These scripts are the files <prgn>preinst</prgn>,
3466 <prgn>postinst</prgn>, <prgn>prerm</prgn> and
3467 <prgn>postrm</prgn> in the control area of the package.
3468 They must be proper executable files; if they are scripts
3469 (which is recommended), they must start with the usual
3470 <tt>#!</tt> convention. They should be readable and
3471 executable by anyone, and must not be world-writable.
3475 The package management system looks at the exit status from
3476 these scripts. It is important that they exit with a
3477 non-zero status if there is an error, so that the package
3478 management system can stop its processing. For shell
3479 scripts this means that you <em>almost always</em> need to
3480 use <tt>set -e</tt> (this is usually true when writing shell
3481 scripts, in fact). It is also important, of course, that
3482 they exit with a zero status if everything went well.
3486 Additionally, packages interacting with users using
3487 <tt>debconf</tt> in the <prgn>postinst</prgn> script should
3488 install a <prgn>config</prgn> script in the control area,
3489 see <ref id="maintscriptprompt"> for details.
3493 When a package is upgraded a combination of the scripts from
3494 the old and new packages is called during the upgrade
3495 procedure. If your scripts are going to be at all
3496 complicated you need to be aware of this, and may need to
3497 check the arguments to your scripts.
3501 Broadly speaking the <prgn>preinst</prgn> is called before
3502 (a particular version of) a package is installed, and the
3503 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3504 before (a version of) a package is removed and the
3505 <prgn>postrm</prgn> afterwards.
3509 Programs called from maintainer scripts should not normally
3510 have a path prepended to them. Before installation is
3511 started, the package management system checks to see if the
3512 programs <prgn>ldconfig</prgn>,
3513 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3514 and <prgn>update-rc.d</prgn> can be found via the
3515 <tt>PATH</tt> environment variable. Those programs, and any
3516 other program that one would expect to be in the
3517 <tt>PATH</tt>, should thus be invoked without an absolute
3518 pathname. Maintainer scripts should also not reset the
3519 <tt>PATH</tt>, though they might choose to modify it by
3520 prepending or appending package-specific directories. These
3521 considerations really apply to all shell scripts.</p>
3524 <sect id="idempotency">
3525 <heading>Maintainer scripts idempotency</heading>
3528 It is necessary for the error recovery procedures that the
3529 scripts be idempotent. This means that if it is run
3530 successfully, and then it is called again, it doesn't bomb
3531 out or cause any harm, but just ensures that everything is
3532 the way it ought to be. If the first call failed, or
3533 aborted half way through for some reason, the second call
3534 should merely do the things that were left undone the first
3535 time, if any, and exit with a success status if everything
3537 This is so that if an error occurs, the user interrupts
3538 <prgn>dpkg</prgn> or some other unforeseen circumstance
3539 happens you don't leave the user with a badly-broken
3540 package when <prgn>dpkg</prgn> attempts to repeat the
3546 <sect id="controllingterminal">
3547 <heading>Controlling terminal for maintainer scripts</heading>
3550 The maintainer scripts are guaranteed to run with a
3551 controlling terminal and can interact with the user.
3552 Because these scripts may be executed with standard output
3553 redirected into a pipe for logging purposes, Perl scripts
3554 should set unbuffered output by setting <tt>$|=1</tt> so
3555 that the output is printed immediately rather than being
3559 <sect id="exitstatus">
3560 <heading>Exit status</heading>
3563 Each script must return a zero exit status for
3564 success, or a nonzero one for failure, since the package
3565 management system looks for the exit status of these scripts
3566 and determines what action to take next based on that datum.
3570 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3575 <list compact="compact">
3577 <var>new-preinst</var> <tt>install</tt>
3580 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3583 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3586 <var>old-preinst</var> <tt>abort-upgrade</tt>
3587 <var>new-version</var>
3592 <list compact="compact">
3594 <var>postinst</var> <tt>configure</tt>
3595 <var>most-recently-configured-version</var>
3598 <var>old-postinst</var> <tt>abort-upgrade</tt>
3599 <var>new-version</var>
3602 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3603 <tt>in-favour</tt> <var>package</var>
3604 <var>new-version</var>
3607 <var>postinst</var> <tt>abort-remove</tt>
3610 <var>deconfigured's-postinst</var>
3611 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3612 <var>failed-install-package</var> <var>version</var>
3613 [<tt>removing</tt> <var>conflicting-package</var>
3619 <list compact="compact">
3621 <var>prerm</var> <tt>remove</tt>
3624 <var>old-prerm</var> <tt>upgrade</tt>
3625 <var>new-version</var>
3628 <var>new-prerm</var> <tt>failed-upgrade</tt>
3629 <var>old-version</var>
3632 <var>conflictor's-prerm</var> <tt>remove</tt>
3633 <tt>in-favour</tt> <var>package</var>
3634 <var>new-version</var>
3637 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3638 <tt>in-favour</tt> <var>package-being-installed</var>
3639 <var>version</var> [<tt>removing</tt>
3640 <var>conflicting-package</var>
3646 <list compact="compact">
3648 <var>postrm</var> <tt>remove</tt>
3651 <var>postrm</var> <tt>purge</tt>
3654 <var>old-postrm</var> <tt>upgrade</tt>
3655 <var>new-version</var>
3658 <var>new-postrm</var> <tt>failed-upgrade</tt>
3659 <var>old-version</var>
3662 <var>new-postrm</var> <tt>abort-install</tt>
3665 <var>new-postrm</var> <tt>abort-install</tt>
3666 <var>old-version</var>
3669 <var>new-postrm</var> <tt>abort-upgrade</tt>
3670 <var>old-version</var>
3673 <var>disappearer's-postrm</var> <tt>disappear</tt>
3674 <var>overwriter</var>
3675 <var>overwriter-version</var>
3681 <sect id="unpackphase">
3682 <heading>Details of unpack phase of installation or upgrade</heading>
3685 The procedure on installation/upgrade/overwrite/disappear
3686 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3687 stage of <tt>dpkg --install</tt>) is as follows. In each
3688 case, if a major error occurs (unless listed below) the
3689 actions are, in general, run backwards - this means that the
3690 maintainer scripts are run with different arguments in
3691 reverse order. These are the "error unwind" calls listed
3698 If a version of the package is already installed, call
3699 <example compact="compact">
3700 <var>old-prerm</var> upgrade <var>new-version</var>
3704 If the script runs but exits with a non-zero
3705 exit status, <prgn>dpkg</prgn> will attempt:
3706 <example compact="compact">
3707 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3709 If this works, the upgrade continues. If this
3710 does not work, the error unwind:
3711 <example compact="compact">
3712 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3714 If this works, then the old-version is
3715 "Installed", if not, the old version is in a
3716 "Failed-Config" state.
3722 If a "conflicting" package is being removed at the same time,
3723 or if any package will be broken (due to <tt>Breaks</tt>):
3726 If <tt>--auto-deconfigure</tt> is
3727 specified, call, for each package to be deconfigured
3728 due to <tt>Breaks</tt>:
3729 <example compact="compact">
3730 <var>deconfigured's-prerm</var> deconfigure \
3731 in-favour <var>package-being-installed</var> <var>version</var>
3734 <example compact="compact">
3735 <var>deconfigured's-postinst</var> abort-deconfigure \
3736 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3738 The deconfigured packages are marked as
3739 requiring configuration, so that if
3740 <tt>--install</tt> is used they will be
3741 configured again if possible.
3744 If any packages depended on a conflicting
3745 package being removed and <tt>--auto-deconfigure</tt> is
3746 specified, call, for each such package:
3747 <example compact="compact">
3748 <var>deconfigured's-prerm</var> deconfigure \
3749 in-favour <var>package-being-installed</var> <var>version</var> \
3750 removing <var>conflicting-package</var> <var>version</var>
3753 <example compact="compact">
3754 <var>deconfigured's-postinst</var> abort-deconfigure \
3755 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3756 removing <var>conflicting-package</var> <var>version</var>
3758 The deconfigured packages are marked as
3759 requiring configuration, so that if
3760 <tt>--install</tt> is used they will be
3761 configured again if possible.
3764 To prepare for removal of each conflicting package, call:
3765 <example compact="compact">
3766 <var>conflictor's-prerm</var> remove \
3767 in-favour <var>package</var> <var>new-version</var>
3770 <example compact="compact">
3771 <var>conflictor's-postinst</var> abort-remove \
3772 in-favour <var>package</var> <var>new-version</var>
3781 If the package is being upgraded, call:
3782 <example compact="compact">
3783 <var>new-preinst</var> upgrade <var>old-version</var>
3785 If this fails, we call:
3787 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3794 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3796 is called. If this works, then the old version
3797 is in an "Installed" state, or else it is left
3798 in an "Unpacked" state.
3803 If it fails, then the old version is left
3804 in an "Half-Installed" state.
3811 Otherwise, if the package had some configuration
3812 files from a previous version installed (i.e., it
3813 is in the "configuration files only" state):
3814 <example compact="compact">
3815 <var>new-preinst</var> install <var>old-version</var>
3819 <var>new-postrm</var> abort-install <var>old-version</var>
3821 If this fails, the package is left in a
3822 "Half-Installed" state, which requires a
3823 reinstall. If it works, the packages is left in
3824 a "Config Files" state.
3827 Otherwise (i.e., the package was completely purged):
3828 <example compact="compact">
3829 <var>new-preinst</var> install
3832 <example compact="compact">
3833 <var>new-postrm</var> abort-install
3835 If the error-unwind fails, the package is in a
3836 "Half Installed" phase, and requires a
3837 reinstall. If the error unwind works, the
3838 package is in a not installed state.
3845 The new package's files are unpacked, overwriting any
3846 that may be on the system already, for example any
3847 from the old version of the same package or from
3848 another package. Backups of the old files are kept
3849 temporarily, and if anything goes wrong the package
3850 management system will attempt to put them back as
3851 part of the error unwind.
3855 It is an error for a package to contain files which
3856 are on the system in another package, unless
3857 <tt>Replaces</tt> is used (see <ref id="replaces">).
3859 The following paragraph is not currently the case:
3860 Currently the <tt>- - force-overwrite</tt> flag is
3861 enabled, downgrading it to a warning, but this may not
3867 It is a more serious error for a package to contain a
3868 plain file or other kind of non-directory where another
3869 package has a directory (again, unless
3870 <tt>Replaces</tt> is used). This error can be
3871 overridden if desired using
3872 <tt>--force-overwrite-dir</tt>, but this is not
3877 Packages which overwrite each other's files produce
3878 behavior which, though deterministic, is hard for the
3879 system administrator to understand. It can easily
3880 lead to "missing" programs if, for example, a package
3881 is installed which overwrites a file from another
3882 package, and is then removed again.<footnote>
3883 Part of the problem is due to what is arguably a
3884 bug in <prgn>dpkg</prgn>.
3889 A directory will never be replaced by a symbolic link
3890 to a directory or vice versa; instead, the existing
3891 state (symlink or not) will be left alone and
3892 <prgn>dpkg</prgn> will follow the symlink if there is
3901 If the package is being upgraded, call
3902 <example compact="compact">
3903 <var>old-postrm</var> upgrade <var>new-version</var>
3907 If this fails, <prgn>dpkg</prgn> will attempt:
3908 <example compact="compact">
3909 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3911 If this works, installation continues. If not,
3913 <example compact="compact">
3914 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3916 If this fails, the old version is left in an
3917 "Half Installed" state. If it works, dpkg now
3919 <example compact="compact">
3920 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3922 If this fails, the old version is left in an
3923 "Half Installed" state. If it works, dpkg now
3925 <example compact="compact">
3926 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3928 If this fails, the old version is in an
3935 This is the point of no return - if
3936 <prgn>dpkg</prgn> gets this far, it won't back off
3937 past this point if an error occurs. This will
3938 leave the package in a fairly bad state, which
3939 will require a successful re-installation to clear
3940 up, but it's when <prgn>dpkg</prgn> starts doing
3941 things that are irreversible.
3946 Any files which were in the old version of the package
3947 but not in the new are removed.
3951 The new file list replaces the old.
3955 The new maintainer scripts replace the old.
3959 Any packages all of whose files have been overwritten
3960 during the installation, and which aren't required for
3961 dependencies, are considered to have been removed.
3962 For each such package
3965 <prgn>dpkg</prgn> calls:
3966 <example compact="compact">
3967 <var>disappearer's-postrm</var> disappear \
3968 <var>overwriter</var> <var>overwriter-version</var>
3972 The package's maintainer scripts are removed.
3975 It is noted in the status database as being in a
3976 sane state, namely not installed (any conffiles
3977 it may have are ignored, rather than being
3978 removed by <prgn>dpkg</prgn>). Note that
3979 disappearing packages do not have their prerm
3980 called, because <prgn>dpkg</prgn> doesn't know
3981 in advance that the package is going to
3988 Any files in the package we're unpacking that are also
3989 listed in the file lists of other packages are removed
3990 from those lists. (This will lobotomize the file list
3991 of the "conflicting" package if there is one.)
3995 The backup files made during installation, above, are
4001 The new package's status is now sane, and recorded as
4006 Here is another point of no return - if the
4007 conflicting package's removal fails we do not unwind
4008 the rest of the installation; the conflicting package
4009 is left in a half-removed limbo.
4014 If there was a conflicting package we go and do the
4015 removal actions (described below), starting with the
4016 removal of the conflicting package's files (any that
4017 are also in the package being installed have already
4018 been removed from the conflicting package's file list,
4019 and so do not get removed now).
4025 <sect id="configdetails"><heading>Details of configuration</heading>
4028 When we configure a package (this happens with <tt>dpkg
4029 --install</tt> and <tt>dpkg --configure</tt>), we first
4030 update any <tt>conffile</tt>s and then call:
4031 <example compact="compact">
4032 <var>postinst</var> configure <var>most-recently-configured-version</var>
4037 No attempt is made to unwind after errors during
4038 configuration. If the configuration fails, the package is in
4039 a "Failed Config" state, and an error message is generated.
4043 If there is no most recently configured version
4044 <prgn>dpkg</prgn> will pass a null argument.
4047 Historical note: Truly ancient (pre-1997) versions of
4048 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4049 (including the angle brackets) in this case. Even older
4050 ones did not pass a second argument at all, under any
4051 circumstance. Note that upgrades using such an old dpkg
4052 version are unlikely to work for other reasons, even if
4053 this old argument behavior is handled by your postinst script.
4059 <sect id="removedetails"><heading>Details of removal and/or
4060 configuration purging</heading>
4066 <example compact="compact">
4067 <var>prerm</var> remove
4071 If prerm fails during replacement due to conflict
4073 <var>conflictor's-postinst</var> abort-remove \
4074 in-favour <var>package</var> <var>new-version</var>
4078 <var>postinst</var> abort-remove
4082 If this fails, the package is in a "Failed-Config"
4083 state, or else it remains "Installed".
4087 The package's files are removed (except <tt>conffile</tt>s).
4090 <example compact="compact">
4091 <var>postrm</var> remove
4095 If it fails, there's no error unwind, and the package is in
4096 an "Half-Installed" state.
4101 All the maintainer scripts except the <prgn>postrm</prgn>
4106 If we aren't purging the package we stop here. Note
4107 that packages which have no <prgn>postrm</prgn> and no
4108 <tt>conffile</tt>s are automatically purged when
4109 removed, as there is no difference except for the
4110 <prgn>dpkg</prgn> status.
4114 The <tt>conffile</tt>s and any backup files
4115 (<tt>~</tt>-files, <tt>#*#</tt> files,
4116 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4121 <example compact="compact">
4122 <var>postrm</var> purge
4126 If this fails, the package remains in a "Config-Files"
4131 The package's file list is removed.
4140 <chapt id="relationships">
4141 <heading>Declaring relationships between packages</heading>
4143 <sect id="depsyntax">
4144 <heading>Syntax of relationship fields</heading>
4147 These fields all have a uniform syntax. They are a list of
4148 package names separated by commas.
4152 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4153 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4154 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4155 control file fields of the package, which declare
4156 dependencies on other packages, the package names listed may
4157 also include lists of alternative package names, separated
4158 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4159 if any one of the alternative packages is installed, that
4160 part of the dependency is considered to be satisfied.
4164 All of the fields except for <tt>Provides</tt> may restrict
4165 their applicability to particular versions of each named
4166 package. This is done in parentheses after each individual
4167 package name; the parentheses should contain a relation from
4168 the list below followed by a version number, in the format
4169 described in <ref id="f-Version">.
4173 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4174 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4175 strictly earlier, earlier or equal, exactly equal, later or
4176 equal and strictly later, respectively. The deprecated
4177 forms <tt><</tt> and <tt>></tt> were used to mean
4178 earlier/later or equal, rather than strictly earlier/later,
4179 so they should not appear in new packages (though
4180 <prgn>dpkg</prgn> still supports them).
4184 Whitespace may appear at any point in the version
4185 specification subject to the rules in <ref
4186 id="controlsyntax">, and must appear where it's necessary to
4187 disambiguate; it is not otherwise significant. All of the
4188 relationship fields may span multiple lines. For
4189 consistency and in case of future changes to
4190 <prgn>dpkg</prgn> it is recommended that a single space be
4191 used after a version relationship and before a version
4192 number; it is also conventional to put a single space after
4193 each comma, on either side of each vertical bar, and before
4194 each open parenthesis. When wrapping a relationship field, it
4195 is conventional to do so after a comma and before the space
4196 following that comma.
4200 For example, a list of dependencies might appear as:
4201 <example compact="compact">
4204 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4209 All fields that specify build-time relationships
4210 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4211 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
4212 may be restricted to a certain set of architectures. This
4213 is indicated in brackets after each individual package name and
4214 the optional version specification. The brackets enclose a
4215 list of Debian architecture names separated by whitespace.
4216 Exclamation marks may be prepended to each of the names.
4217 (It is not permitted for some names to be prepended with
4218 exclamation marks while others aren't.) If the current Debian
4219 host architecture is not in this list and there are no
4220 exclamation marks in the list, or it is in the list with a
4221 prepended exclamation mark, the package name and the
4222 associated version specification are ignored completely for
4223 the purposes of defining the relationships.
4228 <example compact="compact">
4230 Build-Depends-Indep: texinfo
4231 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4232 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4234 requires <tt>kernel-headers-2.2.10</tt> on all architectures
4235 other than hurd-i386 and requires <tt>hurd-dev</tt> and
4236 <tt>gnumach-dev</tt> only on hurd-i386.
4240 If the architecture-restricted dependency is part of a set of
4241 alternatives using <tt>|</tt>, that alternative is ignored
4242 completely on architectures that do not match the restriction.
4244 <example compact="compact">
4245 Build-Depends: foo [!i386] | bar [!amd64]
4247 is equivalent to <tt>bar</tt> on the i386 architecture, to
4248 <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
4249 bar</tt> on all other architectures.
4253 Note that the binary package relationship fields such as
4254 <tt>Depends</tt> appear in one of the binary package
4255 sections of the control file, whereas the build-time
4256 relationships such as <tt>Build-Depends</tt> appear in the
4257 source package section of the control file (which is the
4262 <sect id="binarydeps">
4263 <heading>Binary Dependencies - <tt>Depends</tt>,
4264 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4265 <tt>Pre-Depends</tt>
4269 Packages can declare in their control file that they have
4270 certain relationships to other packages - for example, that
4271 they may not be installed at the same time as certain other
4272 packages, and/or that they depend on the presence of others.
4276 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4277 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4278 <tt>Breaks</tt> and <tt>Conflicts</tt> control file fields.
4279 <tt>Breaks</tt> is described in <ref id="breaks">, and
4280 <tt>Conflicts</tt> is described in <ref id="conflicts">. The
4281 rest are described below.
4285 These seven fields are used to declare a dependency
4286 relationship by one package on another. Except for
4287 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4288 depending (binary) package's control file.
4289 (<tt>Enhances</tt> appears in the recommending package's
4290 control file, and <tt>Breaks</tt> appears in the version of
4291 depended-on package which causes the named package to
4296 A <tt>Depends</tt> field takes effect <em>only</em> when a
4297 package is to be configured. It does not prevent a package
4298 being on the system in an unconfigured state while its
4299 dependencies are unsatisfied, and it is possible to replace
4300 a package whose dependencies are satisfied and which is
4301 properly installed with a different version whose
4302 dependencies are not and cannot be satisfied; when this is
4303 done the depending package will be left unconfigured (since
4304 attempts to configure it will give errors) and will not
4305 function properly. If it is necessary, a
4306 <tt>Pre-Depends</tt> field can be used, which has a partial
4307 effect even when a package is being unpacked, as explained
4308 in detail below. (The other three dependency fields,
4309 <tt>Recommends</tt>, <tt>Suggests</tt> and
4310 <tt>Enhances</tt>, are only used by the various front-ends
4311 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4312 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4316 For this reason packages in an installation run are usually
4317 all unpacked first and all configured later; this gives
4318 later versions of packages with dependencies on later
4319 versions of other packages the opportunity to have their
4320 dependencies satisfied.
4324 In case of circular dependencies, since installation or
4325 removal order honoring the dependency order can't be
4326 established, dependency loops are broken at some point
4327 (based on rules below), and some packages may not be able to
4328 rely on their dependencies being present when being
4329 installed or removed, depending on which side of the break
4330 of the circular dependency loop they happen to be on. If one
4331 of the packages in the loop has no postinst script, then the
4332 cycle will be broken at that package, so as to ensure that
4333 all postinst scripts run with the dependencies properly
4334 configured if this is possible. Otherwise the breaking point
4339 The <tt>Depends</tt> field thus allows package maintainers
4340 to impose an order in which packages should be configured.
4344 The meaning of the five dependency fields is as follows:
4346 <tag><tt>Depends</tt></tag>
4349 This declares an absolute dependency. A package will
4350 not be configured unless all of the packages listed in
4351 its <tt>Depends</tt> field have been correctly
4356 The <tt>Depends</tt> field should be used if the
4357 depended-on package is required for the depending
4358 package to provide a significant amount of
4363 The <tt>Depends</tt> field should also be used if the
4364 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4365 <prgn>postrm</prgn> scripts require the package to be
4366 present in order to run. Note, however, that the
4367 <prgn>postrm</prgn> cannot rely on any non-essential
4368 packages to be present during the <tt>purge</tt>
4372 <tag><tt>Recommends</tt></tag>
4375 This declares a strong, but not absolute, dependency.
4379 The <tt>Recommends</tt> field should list packages
4380 that would be found together with this one in all but
4381 unusual installations.
4385 <tag><tt>Suggests</tt></tag>
4387 This is used to declare that one package may be more
4388 useful with one or more others. Using this field
4389 tells the packaging system and the user that the
4390 listed packages are related to this one and can
4391 perhaps enhance its usefulness, but that installing
4392 this one without them is perfectly reasonable.
4395 <tag><tt>Enhances</tt></tag>
4397 This field is similar to Suggests but works in the
4398 opposite direction. It is used to declare that a
4399 package can enhance the functionality of another
4403 <tag><tt>Pre-Depends</tt></tag>
4406 This field is like <tt>Depends</tt>, except that it
4407 also forces <prgn>dpkg</prgn> to complete installation
4408 of the packages named before even starting the
4409 installation of the package which declares the
4410 pre-dependency, as follows:
4414 When a package declaring a pre-dependency is about to
4415 be <em>unpacked</em> the pre-dependency can be
4416 satisfied if the depended-on package is either fully
4417 configured, <em>or even if</em> the depended-on
4418 package(s) are only unpacked or half-configured,
4419 provided that they have been configured correctly at
4420 some point in the past (and not removed or partially
4421 removed since). In this case, both the
4422 previously-configured and currently unpacked or
4423 half-configured versions must satisfy any version
4424 clause in the <tt>Pre-Depends</tt> field.
4428 When the package declaring a pre-dependency is about
4429 to be <em>configured</em>, the pre-dependency will be
4430 treated as a normal <tt>Depends</tt>, that is, it will
4431 be considered satisfied only if the depended-on
4432 package has been correctly configured.
4436 <tt>Pre-Depends</tt> should be used sparingly,
4437 preferably only by packages whose premature upgrade or
4438 installation would hamper the ability of the system to
4439 continue with any upgrade that might be in progress.
4443 <tt>Pre-Depends</tt> are also required if the
4444 <prgn>preinst</prgn> script depends on the named
4445 package. It is best to avoid this situation if
4453 When selecting which level of dependency to use you should
4454 consider how important the depended-on package is to the
4455 functionality of the one declaring the dependency. Some
4456 packages are composed of components of varying degrees of
4457 importance. Such a package should list using
4458 <tt>Depends</tt> the package(s) which are required by the
4459 more important components. The other components'
4460 requirements may be mentioned as Suggestions or
4461 Recommendations, as appropriate to the components' relative
4467 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4470 When one binary package declares that it breaks another,
4471 <prgn>dpkg</prgn> will refuse to allow the package which
4472 declares <tt>Breaks</tt> be installed unless the broken
4473 package is deconfigured first, and it will refuse to
4474 allow the broken package to be reconfigured.
4478 A package will not be regarded as causing breakage merely
4479 because its configuration files are still installed; it must
4480 be at least half-installed.
4484 A special exception is made for packages which declare that
4485 they break their own package name or a virtual package which
4486 they provide (see below): this does not count as a real
4491 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4492 version clause; such a <tt>Breaks</tt> is introduced in the
4493 version of an (implicit or explicit) dependency which
4494 violates an assumption or reveals a bug in earlier versions
4495 of the broken package. This use of <tt>Breaks</tt> will
4496 inform higher-level package management tools that broken
4497 package must be upgraded before the new one.
4501 If the breaking package also overwrites some files from the
4502 older package, it should use <tt>Replaces</tt> (not
4503 <tt>Conflicts</tt>) to ensure this goes smoothly.
4507 <sect id="conflicts">
4508 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4511 When one binary package declares a conflict with another
4512 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4513 refuse to allow them to be installed on the system at the
4518 If one package is to be installed, the other must be removed
4519 first - if the package being installed is marked as
4520 replacing (see <ref id="replaces">) the one on the system,
4521 or the one on the system is marked as deselected, or both
4522 packages are marked <tt>Essential</tt>, then
4523 <prgn>dpkg</prgn> will automatically remove the package
4524 which is causing the conflict, otherwise it will halt the
4525 installation of the new package with an error. This
4526 mechanism is specifically designed to produce an error when
4527 the installed package is <tt>Essential</tt>, but the new
4532 A package will not cause a conflict merely because its
4533 configuration files are still installed; it must be at least
4538 A special exception is made for packages which declare a
4539 conflict with their own package name, or with a virtual
4540 package which they provide (see below): this does not
4541 prevent their installation, and allows a package to conflict
4542 with others providing a replacement for it. You use this
4543 feature when you want the package in question to be the only
4544 package providing some feature.
4548 A <tt>Conflicts</tt> entry should almost never have an
4549 "earlier than" version clause. This would prevent
4550 <prgn>dpkg</prgn> from upgrading or installing the package
4551 which declared such a conflict until the upgrade or removal
4552 of the conflicted-with package had been completed. Instead,
4553 <tt>Breaks</tt> may be used.
4557 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4561 As well as the names of actual ("concrete") packages, the
4562 package relationship fields <tt>Depends</tt>,
4563 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4564 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4565 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4566 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4567 may mention "virtual packages".
4571 A <em>virtual package</em> is one which appears in the
4572 <tt>Provides</tt> control file field of another package.
4573 The effect is as if the package(s) which provide a
4574 particular virtual package name had been listed by name
4575 everywhere the virtual package name appears. (See also <ref
4580 If there are both concrete and virtual packages of the same
4581 name, then the dependency may be satisfied (or the conflict
4582 caused) by either the concrete package with the name in
4583 question or any other concrete package which provides the
4584 virtual package with the name in question. This is so that,
4585 for example, supposing we have
4586 <example compact="compact">
4589 </example> and someone else releases an enhanced version of
4590 the <tt>bar</tt> package they can say:
4591 <example compact="compact">
4595 and the <tt>bar-plus</tt> package will now also satisfy the
4596 dependency for the <tt>foo</tt> package.
4600 If a relationship field has a version number attached
4601 then only real packages will be considered to see whether
4602 the relationship is satisfied (or the prohibition violated,
4603 for a conflict or breakage) - it is assumed that a real
4604 package which provides the virtual package is not of the
4605 "right" version. So, a <tt>Provides</tt> field may not
4606 contain version numbers, and the version number of the
4607 concrete package which provides a particular virtual package
4608 will not be looked at when considering a dependency on or
4609 conflict with the virtual package name.
4613 It is likely that the ability will be added in a future
4614 release of <prgn>dpkg</prgn> to specify a version number for
4615 each virtual package it provides. This feature is not yet
4616 present, however, and is expected to be used only
4621 If you want to specify which of a set of real packages
4622 should be the default to satisfy a particular dependency on
4623 a virtual package, you should list the real package as an
4624 alternative before the virtual one.
4629 <sect id="replaces"><heading>Overwriting files and replacing
4630 packages - <tt>Replaces</tt></heading>
4633 Packages can declare in their control file that they should
4634 overwrite files in certain other packages, or completely
4635 replace other packages. The <tt>Replaces</tt> control file
4636 field has these two distinct purposes.
4639 <sect1><heading>Overwriting files in other packages</heading>
4642 Firstly, as mentioned before, it is usually an error for a
4643 package to contain files which are on the system in
4648 However, if the overwriting package declares that it
4649 <tt>Replaces</tt> the one containing the file being
4650 overwritten, then <prgn>dpkg</prgn> will replace the file
4651 from the old package with that from the new. The file
4652 will no longer be listed as "owned" by the old package.
4656 If a package is completely replaced in this way, so that
4657 <prgn>dpkg</prgn> does not know of any files it still
4658 contains, it is considered to have "disappeared". It will
4659 be marked as not wanted on the system (selected for
4660 removal) and not installed. Any <tt>conffile</tt>s
4661 details noted for the package will be ignored, as they
4662 will have been taken over by the overwriting package. The
4663 package's <prgn>postrm</prgn> script will be run with a
4664 special argument to allow the package to do any final
4665 cleanup required. See <ref id="mscriptsinstact">.
4668 Replaces is a one way relationship -- you have to
4669 install the replacing package after the replaced
4676 For this usage of <tt>Replaces</tt>, virtual packages (see
4677 <ref id="virtual">) are not considered when looking at a
4678 <tt>Replaces</tt> field - the packages declared as being
4679 replaced must be mentioned by their real names.
4683 Furthermore, this usage of <tt>Replaces</tt> only takes
4684 effect when both packages are at least partially on the
4685 system at once, so that it can only happen if they do not
4686 conflict or if the conflict has been overridden.
4691 <sect1><heading>Replacing whole packages, forcing their
4695 Secondly, <tt>Replaces</tt> allows the packaging system to
4696 resolve which package should be removed when there is a
4697 conflict - see <ref id="conflicts">. This usage only
4698 takes effect when the two packages <em>do</em> conflict,
4699 so that the two usages of this field do not interfere with
4704 In this situation, the package declared as being replaced
4705 can be a virtual package, so for example, all mail
4706 transport agents (MTAs) would have the following fields in
4707 their control files:
4708 <example compact="compact">
4709 Provides: mail-transport-agent
4710 Conflicts: mail-transport-agent
4711 Replaces: mail-transport-agent
4713 ensuring that only one MTA can be installed at any one
4718 <sect id="sourcebinarydeps">
4719 <heading>Relationships between source and binary packages -
4720 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4721 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4725 Source packages that require certain binary packages to be
4726 installed or absent at the time of building the package
4727 can declare relationships to those binary packages.
4731 This is done using the <tt>Build-Depends</tt>,
4732 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4733 <tt>Build-Conflicts-Indep</tt> control file fields.
4737 Build-dependencies on "build-essential" binary packages can be
4738 omitted. Please see <ref id="pkg-relations"> for more information.
4742 The dependencies and conflicts they define must be satisfied
4743 (as defined earlier for binary packages) in order to invoke
4744 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4746 If you make "build-arch" or "binary-arch", you need
4747 Build-Depends. If you make "build-indep" or
4748 "binary-indep", you need Build-Depends and
4749 Build-Depends-Indep. If you make "build" or "binary",
4753 There is no Build-Depends-Arch; this role is essentially
4754 met with Build-Depends. Anyone building the
4755 <tt>build-indep</tt> and binary-indep<tt></tt> targets
4756 is basically assumed to be building the whole package
4757 anyway and so installs all build dependencies. The
4758 autobuilders use <tt>dpkg-buildpackage -B</tt>, which
4759 calls <tt>build</tt> (not <tt>build-arch</tt>, since it
4760 does not yet know how to check for its existence) and
4761 <tt>binary-arch</tt>.
4764 The purpose of the original split, I recall, was so that
4765 the autobuilders wouldn't need to install extra packages
4766 needed only for the binary-indep targets. But without a
4767 build-arch/build-indep split, this didn't work, since
4768 most of the work is done in the build target, not in the
4774 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4776 The <tt>Build-Depends</tt> and
4777 <tt>Build-Conflicts</tt> fields must be satisfied when
4778 any of the following targets is invoked:
4779 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4780 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4781 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4783 <tag><tt>Build-Depends-Indep</tt>,
4784 <tt>Build-Conflicts-Indep</tt></tag>
4786 The <tt>Build-Depends-Indep</tt> and
4787 <tt>Build-Conflicts-Indep</tt> fields must be
4788 satisfied when any of the following targets is
4789 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4790 <tt>binary</tt> and <tt>binary-indep</tt>.
4800 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4803 Packages containing shared libraries must be constructed with
4804 a little care to make sure that the shared library is always
4805 available. This is especially important for packages whose
4806 shared libraries are vitally important, such as the C library
4807 (currently <tt>libc6</tt>).
4811 Packages involving shared libraries should be split up into
4812 several binary packages. This section mostly deals with how
4813 this separation is to be accomplished; rules for files within
4814 the shared library packages are in <ref id="libraries"> instead.
4817 <sect id="sharedlibs-runtime">
4818 <heading>Run-time shared libraries</heading>
4821 The run-time shared library needs to be placed in a package
4822 whose name changes whenever the shared object version
4825 Since it is common place to install several versions of a
4826 package that just provides shared libraries, it is a
4827 good idea that the library package should not
4828 contain any extraneous non-versioned files, unless they
4829 happen to be in versioned directories.</p>
4831 The most common mechanism is to place it in a package
4833 <package><var>libraryname</var><var>soversion</var></package>,
4834 where <file><var>soversion</var></file> is the version number
4835 in the soname of the shared library<footnote>
4836 The soname is the shared object name: it's the thing
4837 that has to match exactly between building an executable
4838 and running it for the dynamic linker to be able run the
4839 program. For example, if the soname of the library is
4840 <file>libfoo.so.6</file>, the library package would be
4841 called <file>libfoo6</file>.
4843 Alternatively, if it would be confusing to directly append
4844 <var>soversion</var> to <var>libraryname</var> (e.g. because
4845 <var>libraryname</var> itself ends in a number), you may use
4846 <package><var>libraryname</var>-<var>soversion</var></package> and
4847 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4852 If you have several shared libraries built from the same
4853 source tree you may lump them all together into a single
4854 shared library package, provided that you change all of
4855 their sonames at once (so that you don't get filename
4856 clashes if you try to install different versions of the
4857 combined shared libraries package).
4861 The package should install the shared libraries under
4862 their normal names. For example, the <package>libgdbm3</package>
4863 package should install <file>libgdbm.so.3.0.0</file> as
4864 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4865 renamed or re-linked by any <prgn>prerm</prgn> or
4866 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4867 of renaming things safely without affecting running programs,
4868 and attempts to interfere with this are likely to lead to
4873 Shared libraries should not be installed executable, since
4874 the dynamic linker does not require this and trying to
4875 execute a shared library usually results in a core dump.
4879 The run-time library package should include the symbolic link that
4880 <prgn>ldconfig</prgn> would create for the shared libraries.
4881 For example, the <package>libgdbm3</package> package should include
4882 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4883 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4884 linker (for example <prgn>ld.so</prgn> or
4885 <prgn>ld-linux.so.*</prgn>) can find the library between the
4886 time that <prgn>dpkg</prgn> installs it and the time that
4887 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4889 The package management system requires the library to be
4890 placed before the symbolic link pointing to it in the
4891 <file>.deb</file> file. This is so that when
4892 <prgn>dpkg</prgn> comes to install the symlink
4893 (overwriting the previous symlink pointing at an older
4894 version of the library), the new shared library is already
4895 in place. In the past, this was achieved by creating the
4896 library in the temporary packaging directory before
4897 creating the symlink. Unfortunately, this was not always
4898 effective, since the building of the tar file in the
4899 <file>.deb</file> depended on the behavior of the underlying
4900 file system. Some file systems (such as reiserfs) reorder
4901 the files so that the order of creation is forgotten.
4902 Since version 1.7.0, <prgn>dpkg</prgn>
4903 reorders the files itself as necessary when building a
4904 package. Thus it is no longer important to concern
4905 oneself with the order of file creation.
4909 <sect1 id="ldconfig">
4910 <heading><tt>ldconfig</tt></heading>
4913 Any package installing shared libraries in one of the default
4914 library directories of the dynamic linker (which are currently
4915 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4916 listed in <file>/etc/ld.so.conf</file><footnote>
4918 <list compact="compact">
4919 <item>/usr/local/lib</item>
4920 <item>/usr/lib/libc5-compat</item>
4921 <item>/lib/libc5-compat</item>
4924 must use <prgn>ldconfig</prgn> to update the shared library
4929 The package maintainer scripts must only call
4930 <prgn>ldconfig</prgn> under these circumstances:
4931 <list compact="compact">
4932 <item>When the <prgn>postinst</prgn> script is run with a
4933 first argument of <tt>configure</tt>, the script must call
4934 <prgn>ldconfig</prgn>, and may optionally invoke
4935 <prgn>ldconfig</prgn> at other times.
4937 <item>When the <prgn>postrm</prgn> script is run with a
4938 first argument of <tt>remove</tt>, the script should call
4939 <prgn>ldconfig</prgn>.
4944 During install or upgrade, the preinst is called before
4945 the new files are installed, so calling "ldconfig" is
4946 pointless. The preinst of an existing package can also be
4947 called if an upgrade fails. However, this happens during
4948 the critical time when a shared libs may exist on-disk
4949 under a temporary name. Thus, it is dangerous and
4950 forbidden by current policy to call "ldconfig" at this
4955 When a package is installed or upgraded, "postinst
4956 configure" runs after the new files are safely on-disk.
4957 Since it is perfectly safe to invoke ldconfig
4958 unconditionally in a postinst, it is OK for a package to
4959 simply put ldconfig in its postinst without checking the
4960 argument. The postinst can also be called to recover from
4961 a failed upgrade. This happens before any new files are
4962 unpacked, so there is no reason to call "ldconfig" at this
4967 For a package that is being removed, prerm is
4968 called with all the files intact, so calling ldconfig is
4969 useless. The other calls to "prerm" happen in the case of
4970 upgrade at a time when all the files of the old package
4971 are on-disk, so again calling "ldconfig" is pointless.
4975 postrm, on the other hand, is called with the "remove"
4976 argument just after the files are removed, so this is
4977 the proper time to call "ldconfig" to notify the system
4978 of the fact that the shared libraries from the package
4979 are removed. The postrm can be called at several other
4980 times. At the time of "postrm purge", "postrm
4981 abort-install", or "postrm abort-upgrade", calling
4982 "ldconfig" is useless because the shared lib files are
4983 not on-disk. However, when "postrm" is invoked with
4984 arguments "upgrade", "failed-upgrade", or "disappear", a
4985 shared lib may exist on-disk under a temporary filename.
4993 <sect id="sharedlibs-support-files">
4994 <heading>Shared library support files</heading>
4997 If your package contains files whose names do not change with
4998 each change in the library shared object version, you must not
4999 put them in the shared library package. Otherwise, several
5000 versions of the shared library cannot be installed at the same
5001 time without filename clashes, making upgrades and transitions
5002 unnecessarily difficult.
5006 It is recommended that supporting files and run-time support
5007 programs that do not need to be invoked manually by users, but
5008 are nevertheless required for the package to function, be placed
5009 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
5010 preferably under <file>/usr/lib/</file><var>package-name</var>.
5011 If the program or file is architecture independent, the
5012 recommendation is for it to be placed in a subdirectory of
5013 <file>/usr/share</file> instead, preferably under
5014 <file>/usr/share/</file><var>package-name</var>. Following the
5015 <var>package-name</var> naming convention ensures that the file
5016 names change when the shared object version changes.
5020 Run-time support programs that use the shared library but are
5021 not required for the library to function or files used by the
5022 shared library that can be used by any version of the shared
5023 library package should instead be put in a separate package.
5024 This package might typically be named
5025 <package><var>libraryname</var>-tools</package>; note the
5026 absence of the <var>soversion</var> in the package name.
5030 Files and support programs only useful when compiling software
5031 against the library should be included in the development
5032 package for the library.<footnote>
5033 For example, a <file><var>package-name</var>-config</file>
5034 script or <package>pkg-config</package> configuration files.
5039 <sect id="sharedlibs-static">
5040 <heading>Static libraries</heading>
5043 The static library (<file><var>libraryname.a</var></file>)
5044 is usually provided in addition to the shared version.
5045 It is placed into the development package (see below).
5049 In some cases, it is acceptable for a library to be
5050 available in static form only; these cases include:
5052 <item>libraries for languages whose shared library support
5053 is immature or unstable</item>
5054 <item>libraries whose interfaces are in flux or under
5055 development (commonly the case when the library's
5056 major version number is zero, or where the ABI breaks
5057 across patchlevels)</item>
5058 <item>libraries which are explicitly intended to be
5059 available only in static form by their upstream
5064 <sect id="sharedlibs-dev">
5065 <heading>Development files</heading>
5068 The development files associated to a shared library need to be
5069 placed in a package called
5070 <package><var>libraryname</var><var>soversion</var>-dev</package>,
5071 or if you prefer only to support one development version at a
5072 time, <package><var>libraryname</var>-dev</package>.
5076 In case several development versions of a library exist, you may
5077 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5078 <ref id="conflicts">) to ensure that the user only installs one
5079 development version at a time (as different development versions are
5080 likely to have the same header files in them, which would cause a
5081 filename clash if both were installed).
5085 The development package should contain a symlink for the associated
5086 shared library without a version number. For example, the
5087 <package>libgdbm-dev</package> package should include a symlink
5088 from <file>/usr/lib/libgdbm.so</file> to
5089 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5090 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5091 <file>libgdbm.so</file> when compiling dynamically.
5095 <sect id="sharedlibs-intradeps">
5096 <heading>Dependencies between the packages of the same library</heading>
5099 Typically the development version should have an exact
5100 version dependency on the runtime library, to make sure that
5101 compilation and linking happens correctly. The
5102 <tt>${binary:Version}</tt> substitution variable can be
5103 useful for this purpose.
5105 Previously, <tt>${Source-Version}</tt> was used, but its name
5106 was confusing and it has been deprecated since dpkg 1.13.19.
5111 <sect id="sharedlibs-shlibdeps">
5112 <heading>Dependencies between the library and other packages -
5113 the <tt>shlibs</tt> system</heading>
5116 If a package contains a binary or library which links to a
5117 shared library, we must ensure that when the package is
5118 installed on the system, all of the libraries needed are
5119 also installed. This requirement led to the creation of the
5120 <tt>shlibs</tt> system, which is very simple in its design:
5121 any package which <em>provides</em> a shared library also
5122 provides information on the package dependencies required to
5123 ensure the presence of this library, and any package which
5124 <em>uses</em> a shared library uses this information to
5125 determine the dependencies it requires. The files which
5126 contain the mapping from shared libraries to the necessary
5127 dependency information are called <file>shlibs</file> files.
5131 Thus, when a package is built which contains any shared
5132 libraries, it must provide a <file>shlibs</file> file for other
5133 packages to use, and when a package is built which contains
5134 any shared libraries or compiled binaries, it must run
5135 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5136 on these to determine the libraries used and hence the
5137 dependencies needed by this package.<footnote>
5139 In the past, the shared libraries linked to were
5140 determined by calling <prgn>ldd</prgn>, but now
5141 <prgn>objdump</prgn> is used to do this. The only
5142 change this makes to package building is that
5143 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
5144 libraries, whereas in the past this was unnecessary.
5145 The rest of this footnote explains the advantage that
5150 We say that a binary <tt>foo</tt> <em>directly</em> uses
5151 a library <tt>libbar</tt> if it is explicitly linked
5152 with that library (that is, it uses the flag
5153 <tt>-lbar</tt> during the linking stage). Other
5154 libraries that are needed by <tt>libbar</tt> are linked
5155 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5156 linker will load them automatically when it loads
5157 <tt>libbar</tt>. A package should depend on
5158 the libraries it directly uses, and the dependencies for
5159 those libraries should automatically pull in the other
5164 Unfortunately, the <prgn>ldd</prgn> program shows both
5165 the directly and indirectly used libraries, meaning that
5166 the dependencies determined included both direct and
5167 indirect dependencies. The use of <prgn>objdump</prgn>
5168 avoids this problem by determining only the directly
5173 A good example of where this helps is the following. We
5174 could update <tt>libimlib</tt> with a new version that
5175 supports a new graphics format called dgf (but retaining
5176 the same major version number). If we used the old
5177 <prgn>ldd</prgn> method, every package that uses
5178 <tt>libimlib</tt> would need to be recompiled so it
5179 would also depend on <tt>libdgf</tt> or it wouldn't run
5180 due to missing symbols. However with the new system,
5181 packages using <tt>libimlib</tt> can rely on
5182 <tt>libimlib</tt> itself having the dependency on
5183 <tt>libdgf</tt> and so they would not need rebuilding.
5189 In the following sections, we will first describe where the
5190 various <tt>shlibs</tt> files are to be found, then how to
5191 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5192 file format and how to create them if your package contains a
5197 <heading>The <tt>shlibs</tt> files present on the system</heading>
5200 There are several places where <tt>shlibs</tt> files are
5201 found. The following list gives them in the order in which
5203 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5204 (The first one which gives the required information is used.)
5210 <p><file>debian/shlibs.local</file></p>
5213 This lists overrides for this package. Its use is
5214 described below (see <ref id="shlibslocal">).
5219 <p><file>/etc/dpkg/shlibs.override</file></p>
5222 This lists global overrides. This list is normally
5223 empty. It is maintained by the local system
5229 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5232 When packages are being built, any
5233 <file>debian/shlibs</file> files are copied into the
5234 control file area of the temporary build directory and
5235 given the name <file>shlibs</file>. These files give
5236 details of any shared libraries included in the
5238 An example may help here. Let us say that the
5239 source package <tt>foo</tt> generates two binary
5240 packages, <tt>libfoo2</tt> and
5241 <tt>foo-runtime</tt>. When building the binary
5242 packages, the two packages are created in the
5243 directories <file>debian/libfoo2</file> and
5244 <file>debian/foo-runtime</file> respectively.
5245 (<file>debian/tmp</file> could be used instead of one
5246 of these.) Since <tt>libfoo2</tt> provides the
5247 <tt>libfoo</tt> shared library, it will require a
5248 <tt>shlibs</tt> file, which will be installed in
5249 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
5251 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
5252 when <prgn>dpkg-shlibdeps</prgn> is run on the
5254 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
5256 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5257 determine whether <tt>foo-prog</tt>'s library
5258 dependencies are satisfied by any of the libraries
5259 provided by <tt>libfoo2</tt>. For this reason,
5260 <prgn>dpkg-shlibdeps</prgn> must only be run once
5261 all of the individual binary packages'
5262 <tt>shlibs</tt> files have been installed into the
5269 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5272 These are the <file>shlibs</file> files corresponding to
5273 all of the packages installed on the system, and are
5274 maintained by the relevant package maintainers.
5279 <p><file>/etc/dpkg/shlibs.default</file></p>
5282 This file lists any shared libraries whose packages
5283 have failed to provide correct <file>shlibs</file> files.
5284 It was used when the <file>shlibs</file> setup was first
5285 introduced, but it is now normally empty. It is
5286 maintained by the <tt>dpkg</tt> maintainer.
5294 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5295 <file>shlibs</file> files</heading>
5299 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5300 into your <file>debian/rules</file> file. If your package
5301 contains only compiled binaries and libraries (but no scripts),
5302 you can use a command such as:
5303 <example compact="compact">
5304 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5305 debian/tmp/usr/lib/*
5307 Otherwise, you will need to explicitly list the compiled
5308 binaries and libraries.<footnote>
5309 If you are using <tt>debhelper</tt>, the
5310 <prgn>dh_shlibdeps</prgn> program will do this work for
5311 you. It will also correctly handle multi-binary
5317 This command puts the dependency information into the
5318 <file>debian/substvars</file> file, which is then used by
5319 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5320 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5321 field in the control file for this to work.
5325 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
5326 done. If it does complain you might need to create your own
5327 <file>debian/shlibs.local</file> file, as explained below (see
5328 <ref id="shlibslocal">).
5332 If you have multiple binary packages, you will need to call
5333 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5334 compiled libraries or binaries. In such a case, you will
5335 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5336 utilities to specify a different <file>substvars</file> file.
5340 If you are creating a udeb for use in the Debian Installer, you
5341 will need to specify that <prgn>dpkg-shlibdeps</prgn> should use
5342 the dependency line of type <tt>udeb</tt> by adding
5343 <tt>-tudeb</tt> as option<footnote>
5344 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5345 will automatically add this option if it knows it is
5347 </footnote>. If there is no dependency line of type <tt>udeb</tt>
5348 in the <file>shlibs</file> file, <prgn>dpkg-shlibdeps</prgn> will
5349 fall back to the regular dependency line.
5353 For more details on dpkg-shlibdeps, please see
5354 <ref id="pkg-dpkg-shlibdeps"> and
5355 <manref name="dpkg-shlibdeps" section="1">.
5360 <heading>The <file>shlibs</file> File Format</heading>
5363 Each <file>shlibs</file> file has the same format. Lines
5364 beginning with <tt>#</tt> are considered to be comments and
5365 are ignored. Each line is of the form:
5366 <example compact="compact">
5367 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5372 We will explain this by reference to the example of the
5373 <tt>zlib1g</tt> package, which (at the time of writing)
5374 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5378 <var>type</var> is an optional element that indicates the type
5379 of package for which the line is valid. The only type currently
5380 in use is <tt>udeb</tt>. The colon and space after the type are
5385 <var>library-name</var> is the name of the shared library,
5386 in this case <tt>libz</tt>. (This must match the name part
5387 of the soname, see below.)
5391 <var>soname-version</var> is the version part of the soname of
5392 the library. The soname is the thing that must exactly match
5393 for the library to be recognized by the dynamic linker, and is
5395 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5396 example, <tt>libz.so.1</tt>.<footnote>
5397 This can be determined using the command
5398 <example compact="compact">
5399 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5402 The version part is the part which comes after
5403 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
5407 <var>dependencies</var> has the same syntax as a dependency
5408 field in a binary package control file. It should give
5409 details of which packages are required to satisfy a binary
5410 built against the version of the library contained in the
5411 package. See <ref id="depsyntax"> for details.
5415 In our example, if the first version of the <tt>zlib1g</tt>
5416 package which contained a minor number of at least
5417 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5418 <tt>shlibs</tt> entry for this library could say:
5419 <example compact="compact">
5420 libz 1 zlib1g (>= 1:1.1.3)
5422 The version-specific dependency is to avoid warnings from
5423 the dynamic linker about using older shared libraries with
5428 As zlib1g also provides a udeb containing the shared library,
5429 there would also be a second line:
5430 <example compact="compact">
5431 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5437 <heading>Providing a <file>shlibs</file> file</heading>
5440 If your package provides a shared library, you need to create
5441 a <file>shlibs</file> file following the format described above.
5442 It is usual to call this file <file>debian/shlibs</file> (but if
5443 you have multiple binary packages, you might want to call it
5444 <file>debian/shlibs.<var>package</var></file> instead). Then
5445 let <file>debian/rules</file> install it in the control area:
5446 <example compact="compact">
5447 install -m644 debian/shlibs debian/tmp/DEBIAN
5449 or, in the case of a multi-binary package:
5450 <example compact="compact">
5451 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5453 An alternative way of doing this is to create the
5454 <file>shlibs</file> file in the control area directly from
5455 <file>debian/rules</file> without using a <file>debian/shlibs</file>
5456 file at all,<footnote>
5457 This is what <prgn>dh_makeshlibs</prgn> in the
5458 <tt>debhelper</tt> suite does. If your package also has a udeb
5459 that provides a shared library, <prgn>dh_makeshlibs</prgn> can
5460 automatically generate the <tt>udeb:</tt> lines if you specify
5461 the name of the udeb with the <tt>--add-udeb</tt> option.
5463 since the <file>debian/shlibs</file> file itself is ignored by
5464 <prgn>dpkg-shlibdeps</prgn>.
5468 As <prgn>dpkg-shlibdeps</prgn> reads the
5469 <file>DEBIAN/shlibs</file> files in all of the binary packages
5470 being built from this source package, all of the
5471 <file>DEBIAN/shlibs</file> files should be installed before
5472 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5477 <sect1 id="shlibslocal">
5478 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
5481 This file is intended only as a <em>temporary</em> fix if
5482 your binaries or libraries depend on a library whose package
5483 does not yet provide a correct <file>shlibs</file> file.
5487 We will assume that you are trying to package a binary
5488 <tt>foo</tt>. When you try running
5489 <prgn>dpkg-shlibdeps</prgn> you get the following error
5490 message (<tt>-O</tt> displays the dependency information on
5491 <tt>stdout</tt> instead of writing it to
5492 <tt>debian/substvars</tt>, and the lines have been wrapped
5493 for ease of reading):
5494 <example compact="compact">
5495 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
5496 dpkg-shlibdeps: warning: unable to find dependency
5497 information for shared library libbar (soname 1,
5498 path /usr/lib/libbar.so.1, dependency field Depends)
5499 shlibs:Depends=libc6 (>= 2.2.2-2)
5501 You can then run <prgn>ldd</prgn> on the binary to find the
5502 full location of the library concerned:
5503 <example compact="compact">
5505 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5506 libc.so.6 => /lib/libc.so.6 (0x40032000)
5507 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5509 So the <prgn>foo</prgn> binary depends on the
5510 <prgn>libbar</prgn> shared library, but no package seems to
5511 provide a <file>*.shlibs</file> file handling
5512 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5513 determine the package responsible:
5514 <example compact="compact">
5515 $ dpkg -S /usr/lib/libbar.so.1
5516 bar1: /usr/lib/libbar.so.1
5517 $ dpkg -s bar1 | grep Version
5520 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5521 is the one we are using. Now we can file a bug against the
5522 <tt>bar1</tt> package and create our own
5523 <file>debian/shlibs.local</file> to locally fix the problem.
5524 Including the following line into your
5525 <file>debian/shlibs.local</file> file:
5526 <example compact="compact">
5527 libbar 1 bar1 (>= 1.0-1)
5529 should allow the package build to work.
5533 As soon as the maintainer of <tt>bar1</tt> provides a
5534 correct <file>shlibs</file> file, you should remove this line
5535 from your <file>debian/shlibs.local</file> file. (You should
5536 probably also then have a versioned <tt>Build-Depends</tt>
5537 on <tt>bar1</tt> to help ensure that others do not have the
5538 same problem building your package.)
5547 <chapt id="opersys"><heading>The Operating System</heading>
5550 <heading>File system hierarchy</heading>
5554 <heading>File System Structure</heading>
5557 The location of all installed files and directories must
5558 comply with the Filesystem Hierarchy Standard (FHS),
5559 version 2.3, with the exceptions noted below, and except
5560 where doing so would violate other terms of Debian
5561 Policy. The following exceptions to the FHS apply:
5566 The optional rules related to user specific
5567 configuration files for applications are stored in
5568 the user's home directory are relaxed. It is
5569 recommended that such files start with the
5570 '<tt>.</tt>' character (a "dot file"), and if an
5571 application needs to create more than one dot file
5572 then the preferred placement is in a subdirectory
5573 with a name starting with a '.' character, (a "dot
5574 directory"). In this case it is recommended the
5575 configuration files not start with the '.'
5581 The requirement for amd64 to use <file>/lib64</file>
5582 for 64 bit binaries is removed.
5587 The requirement for object files, internal binaries, and
5588 libraries, including <file>libc.so.*</file>, to be located
5589 directly under <file>/lib{,32}</file> and
5590 <file>/usr/lib{,32}</file> is amended, permitting files
5591 to instead be installed to
5592 <file>/lib/<var>triplet</var></file> and
5593 <file>/usr/lib/<var>triplet</var></file>, where
5594 <tt><var>triplet</var></tt> is the value returned by
5595 <tt>dpkg-architecture -qDEB_HOST_GNU_TYPE</tt> for the
5596 architecture of the package. Packages may <em>not</em>
5597 install files to any <var>triplet</var> path other
5598 than the one matching the architecture of that package;
5599 for instance, an <tt>Architecture: amd64</tt> package
5600 containing 32-bit x86 libraries may not install these
5601 libraries to <file>/usr/lib/i486-linux-gnu</file>.
5603 This is necessary in order to reserve the directories for
5604 use in cross-installation of library packages from other
5605 architectures, as part of the planned deployment of
5610 Applications may also use a single subdirectory under
5611 <file>/usr/lib/<var>triplet</var></file>.
5614 The execution time linker/loader, ld*, must still be made
5615 available in the existing location under /lib or /lib64
5616 since this is part of the ELF ABI for the architecture.
5621 The requirement that
5622 <file>/usr/local/share/man</file> be "synonymous"
5623 with <file>/usr/local/man</file> is relaxed to a
5628 The requirement that windowmanagers with a single
5629 configuration file call it <file>system.*wmrc</file>
5630 is removed, as is the restriction that the window
5631 manager subdirectory be named identically to the
5632 window manager name itself.
5637 The requirement that boot manager configuration
5638 files live in <file>/etc</file>, or at least are
5639 symlinked there, is relaxed to a recommendation.
5646 The version of this document referred here can be
5647 found in the <tt>debian-policy</tt> package or on <url
5648 id="http://www.debian.org/doc/packaging-manuals/fhs/"
5649 name="FHS (Debian copy)"> alongside this manual (or, if
5650 you have the <package>debian-policy</package> installed,
5652 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5653 (local copy)">). The
5654 latest version, which may be a more recent version, may
5656 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5657 Specific questions about following the standard may be
5658 asked on the <tt>debian-devel</tt> mailing list, or
5659 referred to the FHS mailing list (see the
5660 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5666 <heading>Site-specific programs</heading>
5669 As mandated by the FHS, packages must not place any
5670 files in <file>/usr/local</file>, either by putting them in
5671 the file system archive to be unpacked by <prgn>dpkg</prgn>
5672 or by manipulating them in their maintainer scripts.
5676 However, the package may create empty directories below
5677 <file>/usr/local</file> so that the system administrator knows
5678 where to place site-specific files. These are not
5679 directories <em>in</em> <file>/usr/local</file>, but are
5680 children of directories in <file>/usr/local</file>. These
5681 directories (<file>/usr/local/*/dir/</file>)
5682 should be removed on package removal if they are
5687 Note, that this applies only to directories <em>below</em>
5688 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
5689 Packages must not create sub-directories in the directory
5690 <file>/usr/local</file> itself, except those listed in FHS,
5691 section 4.5. However, you may create directories below
5692 them as you wish. You must not remove any of the
5693 directories listed in 4.5, even if you created them.
5697 Since <file>/usr/local</file> can be mounted read-only from a
5698 remote server, these directories must be created and
5699 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5700 maintainer scripts and not be included in the
5701 <file>.deb</file> archive. These scripts must not fail if
5702 either of these operations fail.
5706 For example, the <tt>emacsen-common</tt> package could
5707 contain something like
5708 <example compact="compact">
5709 if [ ! -e /usr/local/share/emacs ]
5711 if mkdir /usr/local/share/emacs 2>/dev/null
5713 chown root:staff /usr/local/share/emacs
5714 chmod 2775 /usr/local/share/emacs
5718 in its <prgn>postinst</prgn> script, and
5719 <example compact="compact">
5720 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5721 rmdir /usr/local/share/emacs 2>/dev/null || true
5723 in the <prgn>prerm</prgn> script. (Note that this form is
5724 used to ensure that if the script is interrupted, the
5725 directory <file>/usr/local/share/emacs</file> will still be
5730 If you do create a directory in <file>/usr/local</file> for
5731 local additions to a package, you should ensure that
5732 settings in <file>/usr/local</file> take precedence over the
5733 equivalents in <file>/usr</file>.
5737 However, because <file>/usr/local</file> and its contents are
5738 for exclusive use of the local administrator, a package
5739 must not rely on the presence or absence of files or
5740 directories in <file>/usr/local</file> for normal operation.
5744 The <file>/usr/local</file> directory itself and all the
5745 subdirectories created by the package should (by default) have
5746 permissions 2775 (group-writable and set-group-id) and be
5747 owned by <tt>root:staff</tt>.
5752 <heading>The system-wide mail directory</heading>
5754 The system-wide mail directory is <file>/var/mail</file>. This
5755 directory is part of the base system and should not owned
5756 by any particular mail agents. The use of the old
5757 location <file>/var/spool/mail</file> is deprecated, even
5758 though the spool may still be physically located there.
5764 <heading>Users and groups</heading>
5767 <heading>Introduction</heading>
5769 The Debian system can be configured to use either plain or
5774 Some user ids (UIDs) and group ids (GIDs) are reserved
5775 globally for use by certain packages. Because some
5776 packages need to include files which are owned by these
5777 users or groups, or need the ids compiled into binaries,
5778 these ids must be used on any Debian system only for the
5779 purpose for which they are allocated. This is a serious
5780 restriction, and we should avoid getting in the way of
5781 local administration policies. In particular, many sites
5782 allocate users and/or local system groups starting at 100.
5786 Apart from this we should have dynamically allocated ids,
5787 which should by default be arranged in some sensible
5788 order, but the behavior should be configurable.
5792 Packages other than <tt>base-passwd</tt> must not modify
5793 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5794 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5799 <heading>UID and GID classes</heading>
5801 The UID and GID numbers are divided into classes as
5807 Globally allocated by the Debian project, the same
5808 on every Debian system. These ids will appear in
5809 the <file>passwd</file> and <file>group</file> files of all
5810 Debian systems, new ids in this range being added
5811 automatically as the <tt>base-passwd</tt> package is
5816 Packages which need a single statically allocated
5817 uid or gid should use one of these; their
5818 maintainers should ask the <tt>base-passwd</tt>
5826 Dynamically allocated system users and groups.
5827 Packages which need a user or group, but can have
5828 this user or group allocated dynamically and
5829 differently on each system, should use <tt>adduser
5830 --system</tt> to create the group and/or user.
5831 <prgn>adduser</prgn> will check for the existence of
5832 the user or group, and if necessary choose an unused
5833 id based on the ranges specified in
5834 <file>adduser.conf</file>.
5838 <tag>1000-29999:</tag>
5841 Dynamically allocated user accounts. By default
5842 <prgn>adduser</prgn> will choose UIDs and GIDs for
5843 user accounts in this range, though
5844 <file>adduser.conf</file> may be used to modify this
5849 <tag>30000-59999:</tag>
5854 <tag>60000-64999:</tag>
5857 Globally allocated by the Debian project, but only
5858 created on demand. The ids are allocated centrally
5859 and statically, but the actual accounts are only
5860 created on users' systems on demand.
5864 These ids are for packages which are obscure or
5865 which require many statically-allocated ids. These
5866 packages should check for and create the accounts in
5867 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5868 <prgn>adduser</prgn> if it has this facility) if
5869 necessary. Packages which are likely to require
5870 further allocations should have a "hole" left after
5871 them in the allocation, to give them room to
5876 <tag>65000-65533:</tag>
5884 User <tt>nobody</tt>. The corresponding gid refers
5885 to the group <tt>nogroup</tt>.
5892 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5893 not</em> be used, because it is the error return
5902 <sect id="sysvinit">
5903 <heading>System run levels and <file>init.d</file> scripts</heading>
5905 <sect1 id="/etc/init.d">
5906 <heading>Introduction</heading>
5909 The <file>/etc/init.d</file> directory contains the scripts
5910 executed by <prgn>init</prgn> at boot time and when the
5911 init state (or "runlevel") is changed (see <manref
5912 name="init" section="8">).
5916 There are at least two different, yet functionally
5917 equivalent, ways of handling these scripts. For the sake
5918 of simplicity, this document describes only the symbolic
5919 link method. However, it must not be assumed by maintainer
5920 scripts that this method is being used, and any automated
5921 manipulation of the various runlevel behaviors by
5922 maintainer scripts must be performed using
5923 <prgn>update-rc.d</prgn> as described below and not by
5924 manually installing or removing symlinks. For information
5925 on the implementation details of the other method,
5926 implemented in the <tt>file-rc</tt> package, please refer
5927 to the documentation of that package.
5931 These scripts are referenced by symbolic links in the
5932 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5933 runlevels, <prgn>init</prgn> looks in the directory
5934 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5935 execute, where <tt><var>n</var></tt> is the runlevel that
5936 is being changed to, or <tt>S</tt> for the boot-up
5941 The names of the links all have the form
5942 <file>S<var>mm</var><var>script</var></file> or
5943 <file>K<var>mm</var><var>script</var></file> where
5944 <var>mm</var> is a two-digit number and <var>script</var>
5945 is the name of the script (this should be the same as the
5946 name of the actual script in <file>/etc/init.d</file>).
5950 When <prgn>init</prgn> changes runlevel first the targets
5951 of the links whose names start with a <tt>K</tt> are
5952 executed, each with the single argument <tt>stop</tt>,
5953 followed by the scripts prefixed with an <tt>S</tt>, each
5954 with the single argument <tt>start</tt>. (The links are
5955 those in the <file>/etc/rc<var>n</var>.d</file> directory
5956 corresponding to the new runlevel.) The <tt>K</tt> links
5957 are responsible for killing services and the <tt>S</tt>
5958 link for starting services upon entering the runlevel.
5962 For example, if we are changing from runlevel 2 to
5963 runlevel 3, init will first execute all of the <tt>K</tt>
5964 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
5965 all of the <tt>S</tt> prefixed scripts in that directory.
5966 The links starting with <tt>K</tt> will cause the
5967 referred-to file to be executed with an argument of
5968 <tt>stop</tt>, and the <tt>S</tt> links with an argument
5973 The two-digit number <var>mm</var> is used to determine
5974 the order in which to run the scripts: low-numbered links
5975 have their scripts run first. For example, the
5976 <tt>K20</tt> scripts will be executed before the
5977 <tt>K30</tt> scripts. This is used when a certain service
5978 must be started before another. For example, the name
5979 server <prgn>bind</prgn> might need to be started before
5980 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
5981 can set up its access lists. In this case, the script
5982 that starts <prgn>bind</prgn> would have a lower number
5983 than the script that starts <prgn>inn</prgn> so that it
5985 <example compact="compact">
5992 The two runlevels 0 (halt) and 6 (reboot) are slightly
5993 different. In these runlevels, the links with an
5994 <tt>S</tt> prefix are still called after those with a
5995 <tt>K</tt> prefix, but they too are called with the single
5996 argument <tt>stop</tt>.
6001 <heading>Writing the scripts</heading>
6004 Packages that include daemons for system services should
6005 place scripts in <file>/etc/init.d</file> to start or stop
6006 services at boot time or during a change of runlevel.
6007 These scripts should be named
6008 <file>/etc/init.d/<var>package</var></file>, and they should
6009 accept one argument, saying what to do:
6012 <tag><tt>start</tt></tag>
6013 <item>start the service,</item>
6015 <tag><tt>stop</tt></tag>
6016 <item>stop the service,</item>
6018 <tag><tt>restart</tt></tag>
6019 <item>stop and restart the service if it's already running,
6020 otherwise start the service</item>
6022 <tag><tt>reload</tt></tag>
6023 <item><p>cause the configuration of the service to be
6024 reloaded without actually stopping and restarting
6027 <tag><tt>force-reload</tt></tag>
6028 <item>cause the configuration to be reloaded if the
6029 service supports this, otherwise restart the
6033 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
6034 <tt>force-reload</tt> options should be supported by all
6035 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
6040 The <file>init.d</file> scripts must ensure that they will
6041 behave sensibly (i.e., returning success and not starting
6042 multiple copies of a service) if invoked with <tt>start</tt>
6043 when the service is already running, or with <tt>stop</tt>
6044 when it isn't, and that they don't kill unfortunately-named
6045 user processes. The best way to achieve this is usually to
6046 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
6051 If a service reloads its configuration automatically (as
6052 in the case of <prgn>cron</prgn>, for example), the
6053 <tt>reload</tt> option of the <file>init.d</file> script
6054 should behave as if the configuration has been reloaded
6059 The <file>/etc/init.d</file> scripts must be treated as
6060 configuration files, either (if they are present in the
6061 package, that is, in the .deb file) by marking them as
6062 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
6063 by managing them correctly in the maintainer scripts (see
6064 <ref id="config-files">). This is important since we want
6065 to give the local system administrator the chance to adapt
6066 the scripts to the local system, e.g., to disable a
6067 service without de-installing the package, or to specify
6068 some special command line options when starting a service,
6069 while making sure their changes aren't lost during the next
6074 These scripts should not fail obscurely when the
6075 configuration files remain but the package has been
6076 removed, as configuration files remain on the system after
6077 the package has been removed. Only when <prgn>dpkg</prgn>
6078 is executed with the <tt>--purge</tt> option will
6079 configuration files be removed. In particular, as the
6080 <file>/etc/init.d/<var>package</var></file> script itself is
6081 usually a <tt>conffile</tt>, it will remain on the system
6082 if the package is removed but not purged. Therefore, you
6083 should include a <tt>test</tt> statement at the top of the
6085 <example compact="compact">
6086 test -f <var>program-executed-later-in-script</var> || exit 0
6091 Often there are some variables in the <file>init.d</file>
6092 scripts whose values control the behavior of the scripts,
6093 and which a system administrator is likely to want to
6094 change. As the scripts themselves are frequently
6095 <tt>conffile</tt>s, modifying them requires that the
6096 administrator merge in their changes each time the package
6097 is upgraded and the <tt>conffile</tt> changes. To ease
6098 the burden on the system administrator, such configurable
6099 values should not be placed directly in the script.
6100 Instead, they should be placed in a file in
6101 <file>/etc/default</file>, which typically will have the same
6102 base name as the <file>init.d</file> script. This extra file
6103 should be sourced by the script when the script runs. It
6104 must contain only variable settings and comments in SUSv3
6105 <prgn>sh</prgn> format. It may either be a
6106 <tt>conffile</tt> or a configuration file maintained by
6107 the package maintainer scripts. See <ref id="config-files">
6112 To ensure that vital configurable values are always
6113 available, the <file>init.d</file> script should set default
6114 values for each of the shell variables it uses, either
6115 before sourcing the <file>/etc/default/</file> file or
6116 afterwards using something like the <tt>:
6117 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6118 script must behave sensibly and not fail if the
6119 <file>/etc/default</file> file is deleted.
6123 <file>/var/run</file> and <file>/var/lock</file> may be mounted
6124 as temporary filesystems<footnote>
6125 For example, using the <tt>RAMRUN</tt> and <tt>RAMLOCK</tt>
6126 options in <file>/etc/default/rcS</file>.
6127 </footnote>, so the <file>init.d</file> scripts must handle this
6128 correctly. This will typically amount to creating any required
6129 subdirectories dynamically when the <file>init.d</file> script
6130 is run, rather than including them in the package and relying on
6131 <prgn>dpkg</prgn> to create them.
6136 <heading>Interfacing with the initscript system</heading>
6139 Maintainers should use the abstraction layer provided by
6140 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6141 programs to deal with initscripts in their packages'
6142 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6143 and <prgn>postrm</prgn>.
6147 Directly managing the /etc/rc?.d links and directly
6148 invoking the <file>/etc/init.d/</file> initscripts should
6149 be done only by packages providing the initscript
6150 subsystem (such as <prgn>sysv-rc</prgn> and
6151 <prgn>file-rc</prgn>).
6155 <heading>Managing the links</heading>
6158 The program <prgn>update-rc.d</prgn> is provided for
6159 package maintainers to arrange for the proper creation and
6160 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6161 or their functional equivalent if another method is being
6162 used. This may be used by maintainers in their packages'
6163 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6167 You must not include any <file>/etc/rc<var>n</var>.d</file>
6168 symbolic links in the actual archive or manually create or
6169 remove the symbolic links in maintainer scripts; you must
6170 use the <prgn>update-rc.d</prgn> program instead. (The
6171 former will fail if an alternative method of maintaining
6172 runlevel information is being used.) You must not include
6173 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6174 in the archive either. (Only the <tt>sysvinit</tt>
6179 By default <prgn>update-rc.d</prgn> will start services in
6180 each of the multi-user state runlevels (2, 3, 4, and 5)
6181 and stop them in the halt runlevel (0), the single-user
6182 runlevel (1) and the reboot runlevel (6). The system
6183 administrator will have the opportunity to customize
6184 runlevels by simply adding, moving, or removing the
6185 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6186 symbolic links are being used, or by modifying
6187 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6192 To get the default behavior for your package, put in your
6193 <prgn>postinst</prgn> script
6194 <example compact="compact">
6195 update-rc.d <var>package</var> defaults
6197 and in your <prgn>postrm</prgn>
6198 <example compact="compact">
6199 if [ "$1" = purge ]; then
6200 update-rc.d <var>package</var> remove
6202 </example>. Note that if your package changes runlevels
6203 or priority, you may have to remove and recreate the links,
6204 since otherwise the old links may persist. Refer to the
6205 documentation of <prgn>update-rc.d</prgn>.
6209 This will use a default sequence number of 20. If it does
6210 not matter when or in which order the <file>init.d</file>
6211 script is run, use this default. If it does, then you
6212 should talk to the maintainer of the <prgn>sysvinit</prgn>
6213 package or post to <tt>debian-devel</tt>, and they will
6214 help you choose a number.
6218 For more information about using <tt>update-rc.d</tt>,
6219 please consult its man page <manref name="update-rc.d"
6225 <heading>Running initscripts</heading>
6227 The program <prgn>invoke-rc.d</prgn> is provided to make
6228 it easier for package maintainers to properly invoke an
6229 initscript, obeying runlevel and other locally-defined
6230 constraints that might limit a package's right to start,
6231 stop and otherwise manage services. This program may be
6232 used by maintainers in their packages' scripts.
6236 The package maintainer scripts must use
6237 <prgn>invoke-rc.d</prgn> to invoke the
6238 <file>/etc/init.d/*</file> initscripts, instead of
6239 calling them directly.
6243 By default, <prgn>invoke-rc.d</prgn> will pass any
6244 action requests (start, stop, reload, restart...) to the
6245 <file>/etc/init.d</file> script, filtering out requests
6246 to start or restart a service out of its intended
6251 Most packages will simply need to change:
6252 <example compact="compact">/etc/init.d/<package>
6253 <action></example> in their <prgn>postinst</prgn>
6254 and <prgn>prerm</prgn> scripts to:
6255 <example compact="compact">
6256 if which invoke-rc.d >/dev/null 2>&1; then
6257 invoke-rc.d <var>package</var> <action>
6259 /etc/init.d/<var>package</var> <action>
6265 A package should register its initscript services using
6266 <prgn>update-rc.d</prgn> before it tries to invoke them
6267 using <prgn>invoke-rc.d</prgn>. Invocation of
6268 unregistered services may fail.
6272 For more information about using
6273 <prgn>invoke-rc.d</prgn>, please consult its man page
6274 <manref name="invoke-rc.d" section="8">.
6280 <heading>Boot-time initialization</heading>
6283 There used to be another directory, <file>/etc/rc.boot</file>,
6284 which contained scripts which were run once per machine
6285 boot. This has been deprecated in favour of links from
6286 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6287 described in <ref id="/etc/init.d">. Packages must not
6288 place files in <file>/etc/rc.boot</file>.
6293 <heading>Example</heading>
6296 An example on which you can base your
6297 <file>/etc/init.d</file> scripts is found in
6298 <file>/etc/init.d/skeleton</file>.
6305 <heading>Console messages from <file>init.d</file> scripts</heading>
6308 This section describes the formats to be used for messages
6309 written to standard output by the <file>/etc/init.d</file>
6310 scripts. The intent is to improve the consistency of
6311 Debian's startup and shutdown look and feel. For this
6312 reason, please look very carefully at the details. We want
6313 the messages to have the same format in terms of wording,
6314 spaces, punctuation and case of letters.
6318 Here is a list of overall rules that should be used for
6319 messages generated by <file>/etc/init.d</file> scripts.
6325 The message should fit in one line (fewer than 80
6326 characters), start with a capital letter and end with
6327 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6331 If the script is performing some time consuming task in
6332 the background (not merely starting or stopping a
6333 program, for instance), an ellipsis (three dots:
6334 <tt>...</tt>) should be output to the screen, with no
6335 leading or tailing whitespace or line feeds.
6339 The messages should appear as if the computer is telling
6340 the user what it is doing (politely :-), but should not
6341 mention "it" directly. For example, instead of:
6342 <example compact="compact">
6343 I'm starting network daemons: nfsd mountd.
6345 the message should say
6346 <example compact="compact">
6347 Starting network daemons: nfsd mountd.
6354 <tt>init.d</tt> script should use the following standard
6355 message formats for the situations enumerated below.
6361 <p>When daemons are started</p>
6364 If the script starts one or more daemons, the output
6365 should look like this (a single line, no leading
6367 <example compact="compact">
6368 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6370 The <var>description</var> should describe the
6371 subsystem the daemon or set of daemons are part of,
6372 while <var>daemon-1</var> up to <var>daemon-n</var>
6373 denote each daemon's name (typically the file name of
6378 For example, the output of <file>/etc/init.d/lpd</file>
6380 <example compact="compact">
6381 Starting printer spooler: lpd.
6386 This can be achieved by saying
6387 <example compact="compact">
6388 echo -n "Starting printer spooler: lpd"
6389 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6392 in the script. If there are more than one daemon to
6393 start, the output should look like this:
6394 <example compact="compact">
6395 echo -n "Starting remote file system services:"
6396 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6397 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6398 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6401 This makes it possible for the user to see what is
6402 happening and when the final daemon has been started.
6403 Care should be taken in the placement of white spaces:
6404 in the example above the system administrators can
6405 easily comment out a line if they don't want to start
6406 a specific daemon, while the displayed message still
6412 <p>When a system parameter is being set</p>
6415 If you have to set up different system parameters
6416 during the system boot, you should use this format:
6417 <example compact="compact">
6418 Setting <var>parameter</var> to "<var>value</var>".
6423 You can use a statement such as the following to get
6425 <example compact="compact">
6426 echo "Setting DNS domainname to \"$domainname\"."
6431 Note that the same symbol (<tt>"</tt>) <!-- " --> is used
6432 for the left and right quotation marks. A grave accent
6433 (<tt>`</tt>) is not a quote character; neither is an
6434 apostrophe (<tt>'</tt>).
6439 <p>When a daemon is stopped or restarted</p>
6442 When you stop or restart a daemon, you should issue a
6443 message identical to the startup message, except that
6444 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6445 or <tt>Restarting</tt> respectively.
6449 For example, stopping the printer daemon will look like
6451 <example compact="compact">
6452 Stopping printer spooler: lpd.
6458 <p>When something is executed</p>
6461 There are several examples where you have to run a
6462 program at system startup or shutdown to perform a
6463 specific task, for example, setting the system's clock
6464 using <prgn>netdate</prgn> or killing all processes
6465 when the system shuts down. Your message should look
6467 <example compact="compact">
6468 Doing something very useful...done.
6470 You should print the <tt>done.</tt> immediately after
6471 the job has been completed, so that the user is
6472 informed why they have to wait. You can get this
6474 <example compact="compact">
6475 echo -n "Doing something very useful..."
6484 <p>When the configuration is reloaded</p>
6487 When a daemon is forced to reload its configuration
6488 files you should use the following format:
6489 <example compact="compact">
6490 Reloading <var>description</var> configuration...done.
6492 where <var>description</var> is the same as in the
6493 daemon starting message.
6501 <heading>Cron jobs</heading>
6504 Packages must not modify the configuration file
6505 <file>/etc/crontab</file>, and they must not modify the files in
6506 <file>/var/spool/cron/crontabs</file>.</p>
6509 If a package wants to install a job that has to be executed
6510 via cron, it should place a file with the name of the
6511 package in one or more of the following directories:
6512 <example compact="compact">
6518 As these directory names imply, the files within them are
6519 executed on an hourly, daily, weekly, or monthly basis,
6520 respectively. The exact times are listed in
6521 <file>/etc/crontab</file>.</p>
6524 All files installed in any of these directories must be
6525 scripts (e.g., shell scripts or Perl scripts) so that they
6526 can easily be modified by the local system administrator.
6527 In addition, they must be treated as configuration files.
6531 If a certain job has to be executed at some other frequency or
6532 at a specific time, the package should install a file
6533 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6534 same syntax as <file>/etc/crontab</file> and is processed by
6535 <prgn>cron</prgn> automatically. The file must also be
6536 treated as a configuration file. (Note that entries in the
6537 <file>/etc/cron.d</file> directory are not handled by
6538 <prgn>anacron</prgn>. Thus, you should only use this
6539 directory for jobs which may be skipped if the system is not
6543 The scripts or crontab entries in these directories should
6544 check if all necessary programs are installed before they
6545 try to execute them. Otherwise, problems will arise when a
6546 package was removed but not purged since configuration files
6547 are kept on the system in this situation.</p>
6551 <heading>Menus</heading>
6554 The Debian <tt>menu</tt> package provides a standard
6555 interface between packages providing applications and
6556 <em>menu programs</em> (either X window managers or
6557 text-based menu programs such as <prgn>pdmenu</prgn>).
6561 All packages that provide applications that need not be
6562 passed any special command line arguments for normal
6563 operation should register a menu entry for those
6564 applications, so that users of the <tt>menu</tt> package
6565 will automatically get menu entries in their window
6566 managers, as well in shells like <tt>pdmenu</tt>.
6570 Menu entries should follow the current menu policy.
6574 The menu policy can be found in the <tt>menu-policy</tt>
6575 files in the <tt>debian-policy</tt> package.
6576 It is also available from the Debian web mirrors at
6577 <tt><url name="/doc/packaging-manuals/menu-policy/"
6578 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6582 Please also refer to the <em>Debian Menu System</em>
6583 documentation that comes with the <package>menu</package>
6584 package for information about how to register your
6590 <heading>Multimedia handlers</heading>
6593 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6594 is a mechanism for encoding files and data streams and
6595 providing meta-information about them, in particular their
6596 type (e.g. audio or video) and format (e.g. PNG, HTML,
6601 Registration of MIME type handlers allows programs like mail
6602 user agents and web browsers to invoke these handlers to
6603 view, edit or display MIME types they don't support directly.
6607 Packages which provide the ability to view/show/play,
6608 compose, edit or print MIME types should register themselves
6609 as such following the current MIME support policy.
6613 The MIME support policy can be found in the <tt>mime-policy</tt>
6614 files in the <tt>debian-policy</tt> package.
6615 It is also available from the Debian web mirrors at
6616 <tt><url name="/doc/packaging-manuals/mime-policy/"
6617 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6623 <heading>Keyboard configuration</heading>
6626 To achieve a consistent keyboard configuration so that all
6627 applications interpret a keyboard event the same way, all
6628 programs in the Debian distribution must be configured to
6629 comply with the following guidelines.
6633 The following keys must have the specified interpretations:
6636 <tag><tt><--</tt></tag>
6637 <item>delete the character to the left of the cursor</item>
6639 <tag><tt>Delete</tt></tag>
6640 <item>delete the character to the right of the cursor</item>
6642 <tag><tt>Control+H</tt></tag>
6643 <item>emacs: the help prefix</item>
6646 The interpretation of any keyboard events should be
6647 independent of the terminal that is used, be it a virtual
6648 console, an X terminal emulator, an rlogin/telnet session,
6653 The following list explains how the different programs
6654 should be set up to achieve this:
6660 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6664 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6668 X translations are set up to make
6669 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6670 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6671 is the vt220 escape code for the "delete character"
6672 key). This must be done by loading the X resources
6673 using <prgn>xrdb</prgn> on all local X displays, not
6674 using the application defaults, so that the
6675 translation resources used correspond to the
6676 <prgn>xmodmap</prgn> settings.
6680 The Linux console is configured to make
6681 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6682 generate <tt>ESC [ 3 ~</tt>.
6686 X applications are configured so that <tt><</tt>
6687 deletes left, and <tt>Delete</tt> deletes right. Motif
6688 applications already work like this.
6692 Terminals should have <tt>stty erase ^?</tt> .
6696 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6697 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6698 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6702 Emacs is programmed to map <tt>KB_Backspace</tt> or
6703 the <tt>stty erase</tt> character to
6704 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6705 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6706 <tt>^H</tt> to <tt>help</tt> as always.
6710 Other applications use the <tt>stty erase</tt>
6711 character and <tt>kdch1</tt> for the two delete keys,
6712 with ASCII DEL being "delete previous character" and
6713 <tt>kdch1</tt> being "delete character under
6721 This will solve the problem except for the following
6728 Some terminals have a <tt><--</tt> key that cannot
6729 be made to produce anything except <tt>^H</tt>. On
6730 these terminals Emacs help will be unavailable on
6731 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6732 character takes precedence in Emacs, and has been set
6733 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6734 available) can be used instead.
6738 Some operating systems use <tt>^H</tt> for <tt>stty
6739 erase</tt>. However, modern telnet versions and all
6740 rlogin versions propagate <tt>stty</tt> settings, and
6741 almost all UNIX versions honour <tt>stty erase</tt>.
6742 Where the <tt>stty</tt> settings are not propagated
6743 correctly, things can be made to work by using
6744 <tt>stty</tt> manually.
6748 Some systems (including previous Debian versions) use
6749 <prgn>xmodmap</prgn> to arrange for both
6750 <tt><--</tt> and <tt>Delete</tt> to generate
6751 <tt>KB_Delete</tt>. We can change the behavior of
6752 their X clients using the same X resources that we use
6753 to do it for our own clients, or configure our clients
6754 using their resources when things are the other way
6755 around. On displays configured like this
6756 <tt>Delete</tt> will not work, but <tt><--</tt>
6761 Some operating systems have different <tt>kdch1</tt>
6762 settings in their <tt>terminfo</tt> database for
6763 <tt>xterm</tt> and others. On these systems the
6764 <tt>Delete</tt> key will not work correctly when you
6765 log in from a system conforming to our policy, but
6766 <tt><--</tt> will.
6773 <heading>Environment variables</heading>
6776 A program must not depend on environment variables to get
6777 reasonable defaults. (That's because these environment
6778 variables would have to be set in a system-wide
6779 configuration file like <file>/etc/profile</file>, which is not
6780 supported by all shells.)
6784 If a program usually depends on environment variables for its
6785 configuration, the program should be changed to fall back to
6786 a reasonable default configuration if these environment
6787 variables are not present. If this cannot be done easily
6788 (e.g., if the source code of a non-free program is not
6789 available), the program must be replaced by a small
6790 "wrapper" shell script which sets the environment variables
6791 if they are not already defined, and calls the original program.
6795 Here is an example of a wrapper script for this purpose:
6797 <example compact="compact">
6799 BAR=${BAR:-/var/lib/fubar}
6801 exec /usr/lib/foo/foo "$@"
6806 Furthermore, as <file>/etc/profile</file> is a configuration
6807 file of the <prgn>base-files</prgn> package, other packages must
6808 not put any environment variables or other commands into that
6813 <sect id="doc-base">
6814 <heading>Registering Documents using doc-base</heading>
6817 The <package>doc-base</package> package implements a
6818 flexible mechanism for handling and presenting
6819 documentation. The recommended practice is for every Debian
6820 package that provides online documentation (other than just
6821 manual pages) to register these documents with
6822 <package>doc-base</package> by installing a
6823 <package>doc-base</package> control file via the
6824 <prgn/install-docs/ script at installation time and
6825 de-register the manuals again when the package is removed.
6828 Please refer to the documentation that comes with the
6829 <package>doc-base</package> package for information and
6838 <heading>Files</heading>
6841 <heading>Binaries</heading>
6844 Two different packages must not install programs with
6845 different functionality but with the same filenames. (The
6846 case of two programs having the same functionality but
6847 different implementations is handled via "alternatives" or
6848 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6849 <ref id="conflicts"> respectively.) If this case happens,
6850 one of the programs must be renamed. The maintainers should
6851 report this to the <tt>debian-devel</tt> mailing list and
6852 try to find a consensus about which program will have to be
6853 renamed. If a consensus cannot be reached, <em>both</em>
6854 programs must be renamed.
6858 By default, when a package is being built, any binaries
6859 created should include debugging information, as well as
6860 being compiled with optimization. You should also turn on
6861 as many reasonable compilation warnings as possible; this
6862 makes life easier for porters, who can then look at build
6863 logs for possible problems. For the C programming language,
6864 this means the following compilation parameters should be
6866 <example compact="compact">
6868 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6870 INSTALL = install -s # (or use strip on the files in debian/tmp)
6875 Note that by default all installed binaries should be stripped,
6876 either by using the <tt>-s</tt> flag to
6877 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6878 the binaries after they have been copied into
6879 <file>debian/tmp</file> but before the tree is made into a
6884 Although binaries in the build tree should be compiled with
6885 debugging information by default, it can often be difficult to
6886 debug programs if they are also subjected to compiler
6887 optimization. For this reason, it is recommended to support the
6888 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
6889 (see <ref id="debianrules-options">). This variable can contain
6890 several flags to change how a package is compiled and built.
6894 It is up to the package maintainer to decide what
6895 compilation options are best for the package. Certain
6896 binaries (such as computationally-intensive programs) will
6897 function better with certain flags (<tt>-O3</tt>, for
6898 example); feel free to use them. Please use good judgment
6899 here. Don't use flags for the sake of it; only use them
6900 if there is good reason to do so. Feel free to override
6901 the upstream author's ideas about which compilation
6902 options are best: they are often inappropriate for our
6908 <sect id="libraries">
6909 <heading>Libraries</heading>
6912 If the package is <strong>architecture: any</strong>, then
6913 the shared library compilation and linking flags must have
6914 <tt>-fPIC</tt>, or the package shall not build on some of
6915 the supported architectures<footnote>
6917 If you are using GCC, <tt>-fPIC</tt> produces code with
6918 relocatable position independent code, which is required for
6919 most architectures to create a shared library, with i386 and
6920 perhaps some others where non position independent code is
6921 permitted in a shared library.
6924 Position independent code may have a performance penalty,
6925 especially on <tt>i386</tt>. However, in most cases the
6926 speed penalty must be measured against the memory wasted on
6927 the few architectures where non position independent code is
6930 </footnote>. Any exception to this rule must be discussed on
6931 the mailing list <em>debian-devel@lists.debian.org</em>, and
6932 a rough consensus obtained. The reasons for not compiling
6933 with <tt>-fPIC</tt> flag must be recorded in the file
6934 <tt>README.Debian</tt>, and care must be taken to either
6935 restrict the architecture or arrange for <tt>-fPIC</tt> to
6936 be used on architectures where it is required.<footnote>
6938 Some of the reasons why this might be required is if the
6939 library contains hand crafted assembly code that is not
6940 relocatable, the speed penalty is excessive for compute
6941 intensive libs, and similar reasons.
6946 As to the static libraries, the common case is not to have
6947 relocatable code, since there is no benefit, unless in specific
6948 cases; therefore the static version must not be compiled
6949 with the <tt>-fPIC</tt> flag. Any exception to this rule
6950 should be discussed on the mailing list
6951 <em>debian-devel@lists.debian.org</em>, and the reasons for
6952 compiling with the <tt>-fPIC</tt> flag must be recorded in
6953 the file <tt>README.Debian</tt>. <footnote>
6955 Some of the reasons for linking static libraries with
6956 the <tt>-fPIC</tt> flag are if, for example, one needs a
6957 Perl API for a library that is under rapid development,
6958 and has an unstable API, so shared libraries are
6959 pointless at this phase of the library's development. In
6960 that case, since Perl needs a library with relocatable
6961 code, it may make sense to create a static library with
6962 relocatable code. Another reason cited is if you are
6963 distilling various libraries into a common shared
6964 library, like <tt>mklibs</tt> does in the Debian
6970 In other words, if both a shared and a static library is
6971 being built, each source unit (<tt>*.c</tt>, for example,
6972 for C files) will need to be compiled twice, for the normal
6976 You must specify the gcc option <tt>-D_REENTRANT</tt>
6977 when building a library (either static or shared) to make
6978 the library compatible with LinuxThreads.
6982 Although not enforced by the build tools, shared libraries
6983 must be linked against all libraries that they use symbols from
6984 in the same way that binaries are. This ensures the correct
6985 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
6986 system and guarantees that all libraries can be safely opened
6987 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
6988 option <tt>-Wl,-z,defs</tt> when building a shared library.
6989 Since this option enforces symbol resolution at build time,
6990 a missing library reference will be caught early as a fatal
6995 All installed shared libraries should be stripped with
6996 <example compact="compact">
6997 strip --strip-unneeded <var>your-lib</var>
6999 (The option <tt>--strip-unneeded</tt> makes
7000 <prgn>strip</prgn> remove only the symbols which aren't
7001 needed for relocation processing.) Shared libraries can
7002 function perfectly well when stripped, since the symbols for
7003 dynamic linking are in a separate part of the ELF object
7005 You might also want to use the options
7006 <tt>--remove-section=.comment</tt> and
7007 <tt>--remove-section=.note</tt> on both shared libraries
7008 and executables, and <tt>--strip-debug</tt> on static
7014 Note that under some circumstances it may be useful to
7015 install a shared library unstripped, for example when
7016 building a separate package to support debugging.
7020 Shared object files (often <file>.so</file> files) that are not
7021 public libraries, that is, they are not meant to be linked
7022 to by third party executables (binaries of other packages),
7023 should be installed in subdirectories of the
7024 <file>/usr/lib</file> directory. Such files are exempt from the
7025 rules that govern ordinary shared libraries, except that
7026 they must not be installed executable and should be
7028 A common example are the so-called "plug-ins",
7029 internal shared objects that are dynamically loaded by
7030 programs using <manref name="dlopen" section="3">.
7035 An ever increasing number of packages are using
7036 <prgn>libtool</prgn> to do their linking. The latest GNU
7037 libtools (>= 1.3a) can take advantage of the metadata in the
7038 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
7039 files). The main advantage of <prgn>libtool</prgn>'s
7040 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
7041 store and subsequently access metadata with respect to the
7042 libraries it builds. <prgn>libtool</prgn> will search for
7043 those files, which contain a lot of useful information about
7044 a library (such as library dependency information for static
7045 linking). Also, they're <em>essential</em> for programs
7046 using <tt>libltdl</tt>.<footnote>
7047 Although <prgn>libtool</prgn> is fully capable of
7048 linking against shared libraries which don't have
7049 <tt>.la</tt> files, as it is a mere shell script it can
7050 add considerably to the build time of a
7051 <prgn>libtool</prgn>-using package if that shell script
7052 has to derive all this information from first principles
7053 for each library every time it is linked. With the
7054 advent of <prgn>libtool</prgn> version 1.4 (and to a
7055 lesser extent <prgn>libtool</prgn> version 1.3), the
7056 <file>.la</file> files also store information about
7057 inter-library dependencies which cannot necessarily be
7058 derived after the <file>.la</file> file is deleted.
7063 Packages that use <prgn>libtool</prgn> to create shared
7064 libraries should include the <file>.la</file> files in the
7065 <tt>-dev</tt> package, unless the package relies on
7066 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
7067 the <tt>.la</tt> files must go in the run-time library
7072 You must make sure that you use only released versions of
7073 shared libraries to build your packages; otherwise other
7074 users will not be able to run your binaries
7075 properly. Producing source packages that depend on
7076 unreleased compilers is also usually a bad
7083 <heading>Shared libraries</heading>
7085 This section has moved to <ref id="sharedlibs">.
7091 <heading>Scripts</heading>
7094 All command scripts, including the package maintainer
7095 scripts inside the package and used by <prgn>dpkg</prgn>,
7096 should have a <tt>#!</tt> line naming the shell to be used
7101 In the case of Perl scripts this should be
7102 <tt>#!/usr/bin/perl</tt>.
7106 When scripts are installed into a directory in the system
7107 PATH, the script name should not include an extension such
7108 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7109 language currently used to implement it.
7112 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
7113 should almost certainly start with <tt>set -e</tt> so that
7114 errors are detected. Every script should use
7115 <tt>set -e</tt> or check the exit status of <em>every</em>
7120 Scripts may assume that <file>/bin/sh</file> implements the
7121 SUSv3 Shell Command Language<footnote>
7122 Single UNIX Specification, version 3, which is also IEEE
7123 1003.1-2004 (POSIX), and is available on the World Wide Web
7124 from <url id="http://www.unix.org/version3/online.html"
7125 name="The Open Group"> after free
7126 registration.</footnote>
7127 plus the following additional features not mandated by
7129 These features are in widespread use in the Linux community
7130 and are implemented in all of bash, dash, and ksh, the most
7131 common shells users may wish to use as <file>/bin/sh</file>.
7134 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7135 must not generate a newline.</item>
7136 <item><tt>test</tt>, if implemented as a shell built-in, must
7137 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7139 <item><tt>local</tt> to create a scoped variable must be
7140 supported, including listing multiple variables in a single
7141 local command and assigning a value to a variable at the
7142 same time as localizing it. <tt>local</tt> may or
7143 may not preserve the variable value from an outer scope if
7144 no assignment is present. Uses such as:
7148 # ... use a, b, c, d ...
7151 must be supported and must set the value of <tt>c</tt> to
7155 If a shell script requires non-SUSv3 features from the shell
7156 interpreter other than those listed above, the appropriate shell
7157 must be specified in the first line of the script (e.g.,
7158 <tt>#!/bin/bash</tt>) and the package must depend on the package
7159 providing the shell (unless the shell package is marked
7160 "Essential", as in the case of <prgn>bash</prgn>).
7164 You may wish to restrict your script to SUSv3 features plus the
7165 above set when possible so that it may use <file>/bin/sh</file>
7166 as its interpreter. If your script works with <prgn>dash</prgn>
7167 (originally called <prgn>ash</prgn>), it probably complies with
7168 the above requirements, but if you are in doubt, use
7169 <file>/bin/bash</file>.
7173 Perl scripts should check for errors when making any
7174 system calls, including <tt>open</tt>, <tt>print</tt>,
7175 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7179 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7180 scripting languages. See <em>Csh Programming Considered
7181 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7182 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7183 If an upstream package comes with <prgn>csh</prgn> scripts
7184 then you must make sure that they start with
7185 <tt>#!/bin/csh</tt> and make your package depend on the
7186 <prgn>c-shell</prgn> virtual package.
7190 Any scripts which create files in world-writeable
7191 directories (e.g., in <file>/tmp</file>) must use a
7192 mechanism which will fail atomically if a file with the same
7193 name already exists.
7197 The Debian base system provides the <prgn>tempfile</prgn>
7198 and <prgn>mktemp</prgn> utilities for use by scripts for
7205 <heading>Symbolic links</heading>
7208 In general, symbolic links within a top-level directory
7209 should be relative, and symbolic links pointing from one
7210 top-level directory into another should be absolute. (A
7211 top-level directory is a sub-directory of the root
7212 directory <file>/</file>.)
7216 In addition, symbolic links should be specified as short as
7217 possible, i.e., link targets like <file>foo/../bar</file> are
7222 Note that when creating a relative link using
7223 <prgn>ln</prgn> it is not necessary for the target of the
7224 link to exist relative to the working directory you're
7225 running <prgn>ln</prgn> from, nor is it necessary to change
7226 directory to the directory where the link is to be made.
7227 Simply include the string that should appear as the target
7228 of the link (this will be a pathname relative to the
7229 directory in which the link resides) as the first argument
7234 For example, in your <prgn>Makefile</prgn> or
7235 <file>debian/rules</file>, you can do things like:
7236 <example compact="compact">
7237 ln -fs gcc $(prefix)/bin/cc
7238 ln -fs gcc debian/tmp/usr/bin/cc
7239 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7240 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7245 A symbolic link pointing to a compressed file should always
7246 have the same file extension as the referenced file. (For
7247 example, if a file <file>foo.gz</file> is referenced by a
7248 symbolic link, the filename of the link has to end with
7249 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7254 <heading>Device files</heading>
7257 Packages must not include device files in the package file
7262 If a package needs any special device files that are not
7263 included in the base system, it must call
7264 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7265 after notifying the user<footnote>
7266 This notification could be done via a (low-priority)
7267 debconf message, or an echo (printf) statement.
7272 Packages must not remove any device files in the
7273 <prgn>postrm</prgn> or any other script. This is left to the
7274 system administrator.
7278 Debian uses the serial devices
7279 <file>/dev/ttyS*</file>. Programs using the old
7280 <file>/dev/cu*</file> devices should be changed to use
7281 <file>/dev/ttyS*</file>.
7285 <sect id="config-files">
7286 <heading>Configuration files</heading>
7289 <heading>Definitions</heading>
7293 <tag>configuration file</tag>
7295 A file that affects the operation of a program, or
7296 provides site- or host-specific information, or
7297 otherwise customizes the behavior of a program.
7298 Typically, configuration files are intended to be
7299 modified by the system administrator (if needed or
7300 desired) to conform to local policy or to provide
7301 more useful site-specific behavior.
7304 <tag><tt>conffile</tt></tag>
7306 A file listed in a package's <tt>conffiles</tt>
7307 file, and is treated specially by <prgn>dpkg</prgn>
7308 (see <ref id="configdetails">).
7314 The distinction between these two is important; they are
7315 not interchangeable concepts. Almost all
7316 <tt>conffile</tt>s are configuration files, but many
7317 configuration files are not <tt>conffiles</tt>.
7321 As noted elsewhere, <file>/etc/init.d</file> scripts,
7322 <file>/etc/default</file> files, scripts installed in
7323 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7324 configuration installed in <file>/etc/cron.d</file> must be
7325 treated as configuration files. In general, any script that
7326 embeds configuration information is de-facto a configuration
7327 file and should be treated as such.
7332 <heading>Location</heading>
7335 Any configuration files created or used by your package
7336 must reside in <file>/etc</file>. If there are several,
7337 consider creating a subdirectory of <file>/etc</file>
7338 named after your package.
7342 If your package creates or uses configuration files
7343 outside of <file>/etc</file>, and it is not feasible to modify
7344 the package to use <file>/etc</file> directly, put the files
7345 in <file>/etc</file> and create symbolic links to those files
7346 from the location that the package requires.
7351 <heading>Behavior</heading>
7354 Configuration file handling must conform to the following
7356 <list compact="compact">
7358 local changes must be preserved during a package
7362 configuration files must be preserved when the
7363 package is removed, and only deleted when the
7370 The easy way to achieve this behavior is to make the
7371 configuration file a <tt>conffile</tt>. This is
7372 appropriate only if it is possible to distribute a default
7373 version that will work for most installations, although
7374 some system administrators may choose to modify it. This
7375 implies that the default version will be part of the
7376 package distribution, and must not be modified by the
7377 maintainer scripts during installation (or at any other
7382 In order to ensure that local changes are preserved
7383 correctly, no package may contain or make hard links to
7384 conffiles.<footnote>
7385 Rationale: There are two problems with hard links.
7386 The first is that some editors break the link while
7387 editing one of the files, so that the two files may
7388 unwittingly become unlinked and different. The second
7389 is that <prgn>dpkg</prgn> might break the hard link
7390 while upgrading <tt>conffile</tt>s.
7395 The other way to do it is via the maintainer scripts. In
7396 this case, the configuration file must not be listed as a
7397 <tt>conffile</tt> and must not be part of the package
7398 distribution. If the existence of a file is required for
7399 the package to be sensibly configured it is the
7400 responsibility of the package maintainer to provide
7401 maintainer scripts which correctly create, update and
7402 maintain the file and remove it on purge. (See <ref
7403 id="maintainerscripts"> for more information.) These
7404 scripts must be idempotent (i.e., must work correctly if
7405 <prgn>dpkg</prgn> needs to re-run them due to errors
7406 during installation or removal), must cope with all the
7407 variety of ways <prgn>dpkg</prgn> can call maintainer
7408 scripts, must not overwrite or otherwise mangle the user's
7409 configuration without asking, must not ask unnecessary
7410 questions (particularly during upgrades), and must
7411 otherwise be good citizens.
7415 The scripts are not required to configure every possible
7416 option for the package, but only those necessary to get
7417 the package running on a given system. Ideally the
7418 sysadmin should not have to do any configuration other
7419 than that done (semi-)automatically by the
7420 <prgn>postinst</prgn> script.
7424 A common practice is to create a script called
7425 <file><var>package</var>-configure</file> and have the
7426 package's <prgn>postinst</prgn> call it if and only if the
7427 configuration file does not already exist. In certain
7428 cases it is useful for there to be an example or template
7429 file which the maintainer scripts use. Such files should
7430 be in <file>/usr/share/<var>package</var></file> or
7431 <file>/usr/lib/<var>package</var></file> (depending on whether
7432 they are architecture-independent or not). There should
7433 be symbolic links to them from
7434 <file>/usr/share/doc/<var>package</var>/examples</file> if
7435 they are examples, and should be perfectly ordinary
7436 <prgn>dpkg</prgn>-handled files (<em>not</em>
7437 configuration files).
7441 These two styles of configuration file handling must
7442 not be mixed, for that way lies madness:
7443 <prgn>dpkg</prgn> will ask about overwriting the file
7444 every time the package is upgraded.
7449 <heading>Sharing configuration files</heading>
7452 Packages which specify the same file as a
7453 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7454 with each other. (This is an instance of the general rule
7455 about not sharing files. Note that neither alternatives
7456 nor diversions are likely to be appropriate in this case;
7457 in particular, <prgn>dpkg</prgn> does not handle diverted
7458 <tt>conffile</tt>s well.)
7462 The maintainer scripts must not alter a <tt>conffile</tt>
7463 of <em>any</em> package, including the one the scripts
7468 If two or more packages use the same configuration file
7469 and it is reasonable for both to be installed at the same
7470 time, one of these packages must be defined as
7471 <em>owner</em> of the configuration file, i.e., it will be
7472 the package which handles that file as a configuration
7473 file. Other packages that use the configuration file must
7474 depend on the owning package if they require the
7475 configuration file to operate. If the other package will
7476 use the configuration file if present, but is capable of
7477 operating without it, no dependency need be declared.
7481 If it is desirable for two or more related packages to
7482 share a configuration file <em>and</em> for all of the
7483 related packages to be able to modify that configuration
7484 file, then the following should be done:
7485 <enumlist compact="compact">
7487 One of the related packages (the "owning" package)
7488 will manage the configuration file with maintainer
7489 scripts as described in the previous section.
7492 The owning package should also provide a program
7493 that the other packages may use to modify the
7497 The related packages must use the provided program
7498 to make any desired modifications to the
7499 configuration file. They should either depend on
7500 the core package to guarantee that the configuration
7501 modifier program is available or accept gracefully
7502 that they cannot modify the configuration file if it
7503 is not. (This is in addition to the fact that the
7504 configuration file may not even be present in the
7511 Sometimes it's appropriate to create a new package which
7512 provides the basic infrastructure for the other packages
7513 and which manages the shared configuration files. (The
7514 <tt>sgml-base</tt> package is a good example.)
7519 <heading>User configuration files ("dotfiles")</heading>
7522 The files in <file>/etc/skel</file> will automatically be
7523 copied into new user accounts by <prgn>adduser</prgn>.
7524 No other program should reference the files in
7525 <file>/etc/skel</file>.
7529 Therefore, if a program needs a dotfile to exist in
7530 advance in <file>$HOME</file> to work sensibly, that dotfile
7531 should be installed in <file>/etc/skel</file> and treated as a
7536 However, programs that require dotfiles in order to
7537 operate sensibly are a bad thing, unless they do create
7538 the dotfiles themselves automatically.
7542 Furthermore, programs should be configured by the Debian
7543 default installation to behave as closely to the upstream
7544 default behavior as possible.
7548 Therefore, if a program in a Debian package needs to be
7549 configured in some way in order to operate sensibly, that
7550 should be done using a site-wide configuration file placed
7551 in <file>/etc</file>. Only if the program doesn't support a
7552 site-wide default configuration and the package maintainer
7553 doesn't have time to add it may a default per-user file be
7554 placed in <file>/etc/skel</file>.
7558 <file>/etc/skel</file> should be as empty as we can make it.
7559 This is particularly true because there is no easy (or
7560 necessarily desirable) mechanism for ensuring that the
7561 appropriate dotfiles are copied into the accounts of
7562 existing users when a package is installed.
7568 <heading>Log files</heading>
7570 Log files should usually be named
7571 <file>/var/log/<var>package</var>.log</file>. If you have many
7572 log files, or need a separate directory for permission
7573 reasons (<file>/var/log</file> is writable only by
7574 <file>root</file>), you should usually create a directory named
7575 <file>/var/log/<var>package</var></file> and place your log
7580 Log files must be rotated occasionally so that they don't
7581 grow indefinitely; the best way to do this is to drop a log
7582 rotation configuration file into the directory
7583 <file>/etc/logrotate.d</file> and use the facilities provided by
7584 logrotate.<footnote>
7586 The traditional approach to log files has been to set up
7587 <em>ad hoc</em> log rotation schemes using simple shell
7588 scripts and cron. While this approach is highly
7589 customizable, it requires quite a lot of sysadmin work.
7590 Even though the original Debian system helped a little
7591 by automatically installing a system which can be used
7592 as a template, this was deemed not enough.
7596 The use of <prgn>logrotate</prgn>, a program developed
7597 by Red Hat, is better, as it centralizes log management.
7598 It has both a configuration file
7599 (<file>/etc/logrotate.conf</file>) and a directory where
7600 packages can drop their individual log rotation
7601 configurations (<file>/etc/logrotate.d</file>).
7604 Here is a good example for a logrotate config
7605 file (for more information see <manref name="logrotate"
7607 <example compact="compact">
7608 /var/log/foo/*.log {
7613 /etc/init.d/foo force-reload
7617 This rotates all files under <file>/var/log/foo</file>, saves 12
7618 compressed generations, and forces the daemon to reload its
7619 configuration information after the log rotation.
7623 Log files should be removed when the package is
7624 purged (but not when it is only removed). This should be
7625 done by the <prgn>postrm</prgn> script when it is called
7626 with the argument <tt>purge</tt> (see <ref
7627 id="removedetails">).
7632 <heading>Permissions and owners</heading>
7635 The rules in this section are guidelines for general use.
7636 If necessary you may deviate from the details below.
7637 However, if you do so you must make sure that what is done
7638 is secure and you should try to be as consistent as possible
7639 with the rest of the system. You should probably also
7640 discuss it on <prgn>debian-devel</prgn> first.
7644 Files should be owned by <tt>root:root</tt>, and made
7645 writable only by the owner and universally readable (and
7646 executable, if appropriate), that is mode 644 or 755.
7650 Directories should be mode 755 or (for group-writability)
7651 mode 2775. The ownership of the directory should be
7652 consistent with its mode: if a directory is mode 2775, it
7653 should be owned by the group that needs write access to
7656 When a package is upgraded, and the owner or permissions
7657 of a file included in the package has changed, dpkg
7658 arranges for the ownership and permissions to be
7659 correctly set upon installation. However, this does not
7660 extend to directories; the permissions and ownership of
7661 directories already on the system does not change on
7662 install or upgrade of packages. This makes sense, since
7663 otherwise common directories like <tt>/usr</tt> would
7664 always be in flux. To correctly change permissions of a
7665 directory the package owns, explicit action is required,
7666 usually in the <tt>postinst</tt> script. Care must be
7667 taken to handle downgrades as well, in that case.
7674 Setuid and setgid executables should be mode 4755 or 2755
7675 respectively, and owned by the appropriate user or group.
7676 They should not be made unreadable (modes like 4711 or
7677 2711 or even 4111); doing so achieves no extra security,
7678 because anyone can find the binary in the freely available
7679 Debian package; it is merely inconvenient. For the same
7680 reason you should not restrict read or execute permissions
7681 on non-set-id executables.
7685 Some setuid programs need to be restricted to particular
7686 sets of users, using file permissions. In this case they
7687 should be owned by the uid to which they are set-id, and by
7688 the group which should be allowed to execute them. They
7689 should have mode 4754; again there is no point in making
7690 them unreadable to those users who must not be allowed to
7695 It is possible to arrange that the system administrator can
7696 reconfigure the package to correspond to their local
7697 security policy by changing the permissions on a binary:
7698 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7699 described below.<footnote>
7700 Ordinary files installed by <prgn>dpkg</prgn> (as
7701 opposed to <tt>conffile</tt>s and other similar objects)
7702 normally have their permissions reset to the distributed
7703 permissions when the package is reinstalled. However,
7704 the use of <prgn>dpkg-statoverride</prgn> overrides this
7705 default behavior. If you use this method, you should
7706 remember to describe <prgn>dpkg-statoverride</prgn> in
7707 the package documentation; being a relatively new
7708 addition to Debian, it is probably not yet well-known.
7710 Another method you should consider is to create a group for
7711 people allowed to use the program(s) and make any setuid
7712 executables executable only by that group.
7716 If you need to create a new user or group for your package
7717 there are two possibilities. Firstly, you may need to
7718 make some files in the binary package be owned by this
7719 user or group, or you may need to compile the user or
7720 group id (rather than just the name) into the binary
7721 (though this latter should be avoided if possible, as in
7722 this case you need a statically allocated id).</p>
7725 If you need a statically allocated id, you must ask for a
7726 user or group id from the <tt>base-passwd</tt> maintainer,
7727 and must not release the package until you have been
7728 allocated one. Once you have been allocated one you must
7729 either make the package depend on a version of the
7730 <tt>base-passwd</tt> package with the id present in
7731 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7732 your package to create the user or group itself with the
7733 correct id (using <tt>adduser</tt>) in its
7734 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7735 the <prgn>postinst</prgn> is to be preferred if it is
7736 possible, otherwise a pre-dependency will be needed on the
7737 <tt>adduser</tt> package.)
7741 On the other hand, the program might be able to determine
7742 the uid or gid from the user or group name at runtime, so
7743 that a dynamically allocated id can be used. In this case
7744 you should choose an appropriate user or group name,
7745 discussing this on <prgn>debian-devel</prgn> and checking
7746 with the <package/base-passwd/ maintainer that it is unique and that
7747 they do not wish you to use a statically allocated id
7748 instead. When this has been checked you must arrange for
7749 your package to create the user or group if necessary using
7750 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7751 <prgn>postinst</prgn> script (again, the latter is to be
7752 preferred if it is possible).
7756 Note that changing the numeric value of an id associated
7757 with a name is very difficult, and involves searching the
7758 file system for all appropriate files. You need to think
7759 carefully whether a static or dynamic id is required, since
7760 changing your mind later will cause problems.
7763 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7765 This section is not intended as policy, but as a
7766 description of the use of <prgn>dpkg-statoverride</prgn>.
7770 If a system administrator wishes to have a file (or
7771 directory or other such thing) installed with owner and
7772 permissions different from those in the distributed Debian
7773 package, they can use the <prgn>dpkg-statoverride</prgn>
7774 program to instruct <prgn>dpkg</prgn> to use the different
7775 settings every time the file is installed. Thus the
7776 package maintainer should distribute the files with their
7777 normal permissions, and leave it for the system
7778 administrator to make any desired changes. For example, a
7779 daemon which is normally required to be setuid root, but
7780 in certain situations could be used without being setuid,
7781 should be installed setuid in the <tt>.deb</tt>. Then the
7782 local system administrator can change this if they wish.
7783 If there are two standard ways of doing it, the package
7784 maintainer can use <tt>debconf</tt> to find out the
7785 preference, and call <prgn>dpkg-statoverride</prgn> in the
7786 maintainer script if necessary to accommodate the system
7787 administrator's choice. Care must be taken during
7788 upgrades to not override an existing setting.
7792 Given the above, <prgn>dpkg-statoverride</prgn> is
7793 essentially a tool for system administrators and would not
7794 normally be needed in the maintainer scripts. There is
7795 one type of situation, though, where calls to
7796 <prgn>dpkg-statoverride</prgn> would be needed in the
7797 maintainer scripts, and that involves packages which use
7798 dynamically allocated user or group ids. In such a
7799 situation, something like the following idiom can be very
7800 helpful in the package's <prgn>postinst</prgn>, where
7801 <tt>sysuser</tt> is a dynamically allocated id:
7803 for i in /usr/bin/foo /usr/sbin/bar
7805 # only do something when no setting exists
7806 if ! dpkg-statoverride --list $i >/dev/null 2>&1
7808 #include: debconf processing, question about foo and bar
7809 if [ "$RET" = "true" ] ; then
7810 dpkg-statoverride --update --add sysuser root 4755 $i
7815 The corresponding code to remove the override when the package
7818 for i in /usr/bin/foo /usr/sbin/bar
7820 if dpkg-statoverride --list $i >/dev/null 2>&1
7822 dpkg-statoverride --remove $i
7832 <chapt id="customized-programs">
7833 <heading>Customized programs</heading>
7835 <sect id="arch-spec">
7836 <heading>Architecture specification strings</heading>
7839 If a program needs to specify an <em>architecture specification
7840 string</em> in some place, it should select one of the
7841 strings provided by <tt>dpkg-architecture -L</tt>. The
7842 strings are in the format
7843 <tt><var>os</var>-<var>arch</var></tt>, though the OS part
7844 is sometimes elided, as when the OS is Linux.<footnote>
7845 <p>Currently, the strings are:
7846 i386 ia64 alpha amd64 armeb arm hppa m32r m68k mips
7847 mipsel powerpc ppc64 s390 s390x sh3 sh3eb sh4 sh4eb
7848 sparc darwin-i386 darwin-ia64 darwin-alpha darwin-amd64
7849 darwin-armeb darwin-arm darwin-hppa darwin-m32r
7850 darwin-m68k darwin-mips darwin-mipsel darwin-powerpc
7851 darwin-ppc64 darwin-s390 darwin-s390x darwin-sh3
7852 darwin-sh3eb darwin-sh4 darwin-sh4eb darwin-sparc
7853 freebsd-i386 freebsd-ia64 freebsd-alpha freebsd-amd64
7854 freebsd-armeb freebsd-arm freebsd-hppa freebsd-m32r
7855 freebsd-m68k freebsd-mips freebsd-mipsel freebsd-powerpc
7856 freebsd-ppc64 freebsd-s390 freebsd-s390x freebsd-sh3
7857 freebsd-sh3eb freebsd-sh4 freebsd-sh4eb freebsd-sparc
7858 kfreebsd-i386 kfreebsd-ia64 kfreebsd-alpha
7859 kfreebsd-amd64 kfreebsd-armeb kfreebsd-arm kfreebsd-hppa
7860 kfreebsd-m32r kfreebsd-m68k kfreebsd-mips
7861 kfreebsd-mipsel kfreebsd-powerpc kfreebsd-ppc64
7862 kfreebsd-s390 kfreebsd-s390x kfreebsd-sh3 kfreebsd-sh3eb
7863 kfreebsd-sh4 kfreebsd-sh4eb kfreebsd-sparc knetbsd-i386
7864 knetbsd-ia64 knetbsd-alpha knetbsd-amd64 knetbsd-armeb
7865 knetbsd-arm knetbsd-hppa knetbsd-m32r knetbsd-m68k
7866 knetbsd-mips knetbsd-mipsel knetbsd-powerpc
7867 knetbsd-ppc64 knetbsd-s390 knetbsd-s390x knetbsd-sh3
7868 knetbsd-sh3eb knetbsd-sh4 knetbsd-sh4eb knetbsd-sparc
7869 netbsd-i386 netbsd-ia64 netbsd-alpha netbsd-amd64
7870 netbsd-armeb netbsd-arm netbsd-hppa netbsd-m32r
7871 netbsd-m68k netbsd-mips netbsd-mipsel netbsd-powerpc
7872 netbsd-ppc64 netbsd-s390 netbsd-s390x netbsd-sh3
7873 netbsd-sh3eb netbsd-sh4 netbsd-sh4eb netbsd-sparc
7874 openbsd-i386 openbsd-ia64 openbsd-alpha openbsd-amd64
7875 openbsd-armeb openbsd-arm openbsd-hppa openbsd-m32r
7876 openbsd-m68k openbsd-mips openbsd-mipsel openbsd-powerpc
7877 openbsd-ppc64 openbsd-s390 openbsd-s390x openbsd-sh3
7878 openbsd-sh3eb openbsd-sh4 openbsd-sh4eb openbsd-sparc
7879 hurd-i386 hurd-ia64 hurd-alpha hurd-amd64 hurd-armeb
7880 hurd-arm hurd-hppa hurd-m32r hurd-m68k hurd-mips
7881 hurd-mipsel hurd-powerpc hurd-ppc64 hurd-s390 hurd-s390x
7882 hurd-sh3 hurd-sh3eb hurd-sh4 hurd-sh4eb hurd-sparc
7888 Note that we don't want to use
7889 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7890 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7891 since this would make our programs incompatible with other
7892 Linux distributions. We also don't use something like
7893 <tt><var>arch</var>-unknown-linux</tt>, since the
7894 <tt>unknown</tt> does not look very good.
7899 <heading>Daemons</heading>
7902 The configuration files <file>/etc/services</file>,
7903 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7904 by the <prgn>netbase</prgn> package and must not be modified
7909 If a package requires a new entry in one of these files, the
7910 maintainer should get in contact with the
7911 <prgn>netbase</prgn> maintainer, who will add the entries
7912 and release a new version of the <prgn>netbase</prgn>
7917 The configuration file <file>/etc/inetd.conf</file> must not be
7918 modified by the package's scripts except via the
7919 <prgn>update-inetd</prgn> script or the
7920 <file>DebianNet.pm</file> Perl module. See their documentation
7921 for details on how to add entries.
7925 If a package wants to install an example entry into
7926 <file>/etc/inetd.conf</file>, the entry must be preceded with
7927 exactly one hash character (<tt>#</tt>). Such lines are
7928 treated as "commented out by user" by the
7929 <prgn>update-inetd</prgn> script and are not changed or
7930 activated during package updates.
7935 <heading>Using pseudo-ttys and modifying wtmp, utmp and
7939 Some programs need to create pseudo-ttys. This should be done
7940 using Unix98 ptys if the C library supports it. The resulting
7941 program must not be installed setuid root, unless that
7942 is required for other functionality.
7946 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
7947 <file>/var/log/lastlog</file> must be installed writable by
7948 group <tt>utmp</tt>. Programs which need to modify those
7949 files must be installed setgid <tt>utmp</tt>.
7954 <heading>Editors and pagers</heading>
7957 Some programs have the ability to launch an editor or pager
7958 program to edit or display a text document. Since there are
7959 lots of different editors and pagers available in the Debian
7960 distribution, the system administrator and each user should
7961 have the possibility to choose their preferred editor and
7966 In addition, every program should choose a good default
7967 editor/pager if none is selected by the user or system
7972 Thus, every program that launches an editor or pager must
7973 use the EDITOR or PAGER environment variable to determine
7974 the editor or pager the user wishes to use. If these
7975 variables are not set, the programs <file>/usr/bin/editor</file>
7976 and <file>/usr/bin/pager</file> should be used, respectively.
7980 These two files are managed through the <prgn>dpkg</prgn>
7981 "alternatives" mechanism. Thus every package providing an
7982 editor or pager must call the
7983 <prgn>update-alternatives</prgn> script to register these
7988 If it is very hard to adapt a program to make use of the
7989 EDITOR or PAGER variables, that program may be configured to
7990 use <file>/usr/bin/sensible-editor</file> and
7991 <file>/usr/bin/sensible-pager</file> as the editor or pager
7992 program respectively. These are two scripts provided in the
7993 <package>sensible-utils</package> package that check the EDITOR
7994 and PAGER variables and launch the appropriate program, and fall
7995 back to <file>/usr/bin/editor</file>
7996 and <file>/usr/bin/pager</file> if the variable is not set.
8000 A program may also use the VISUAL environment variable to
8001 determine the user's choice of editor. If it exists, it
8002 should take precedence over EDITOR. This is in fact what
8003 <file>/usr/bin/sensible-editor</file> does.
8007 It is not required for a package to depend on
8008 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
8009 package to provide such virtual packages.<footnote>
8010 The Debian base system already provides an editor and a
8016 <sect id="web-appl">
8017 <heading>Web servers and applications</heading>
8020 This section describes the locations and URLs that should
8021 be used by all web servers and web applications in the
8028 Cgi-bin executable files are installed in the
8030 <example compact="compact">
8031 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
8033 and should be referred to as
8034 <example compact="compact">
8035 http://localhost/cgi-bin/<var>cgi-bin-name</var>
8041 <p>Access to HTML documents</p>
8044 HTML documents for a package are stored in
8045 <file>/usr/share/doc/<var>package</var></file>
8046 and can be referred to as
8047 <example compact="compact">
8048 http://localhost/doc/<var>package</var>/<var>filename</var>
8053 The web server should restrict access to the document
8054 tree so that only clients on the same host can read
8055 the documents. If the web server does not support such
8056 access controls, then it should not provide access at
8057 all, or ask about providing access during installation.
8062 <p>Access to images</p>
8064 It is recommended that images for a package be stored
8065 in <tt>/usr/share/images/<var>package</var></tt> and
8066 may be referred to through an alias <tt>/images/</tt>
8069 http://localhost/images/<package>/<filename>
8076 <p>Web Document Root</p>
8079 Web Applications should try to avoid storing files in
8080 the Web Document Root. Instead they should use the
8081 /usr/share/doc/<var>package</var> directory for
8082 documents and register the Web Application via the
8083 <package>doc-base</package> package. If access to the
8084 web document root is unavoidable then use
8085 <example compact="compact">
8088 as the Document Root. This might be just a symbolic
8089 link to the location where the system administrator
8090 has put the real document root.
8093 <item><p>Providing httpd and/or httpd-cgi</p>
8095 All web servers should provide the virtual package
8096 <tt>httpd</tt>. If a web server has CGI support it should
8097 provide <tt>httpd-cgi</tt> additionally.
8100 All web applications which do not contain CGI scripts should
8101 depend on <tt>httpd</tt>, all those web applications which
8102 <tt>do</tt> contain CGI scripts, should depend on
8110 <sect id="mail-transport-agents">
8111 <heading>Mail transport, delivery and user agents</heading>
8114 Debian packages which process electronic mail, whether mail
8115 user agents (MUAs) or mail transport agents (MTAs), must
8116 ensure that they are compatible with the configuration
8117 decisions below. Failure to do this may result in lost
8118 mail, broken <tt>From:</tt> lines, and other serious brain
8123 The mail spool is <file>/var/mail</file> and the interface to
8124 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8125 the FHS). On older systems, the mail spool may be
8126 physically located in <file>/var/spool/mail</file>, but all
8127 access to the mail spool should be via the
8128 <file>/var/mail</file> symlink. The mail spool is part of the
8129 base system and not part of the MTA package.
8133 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8134 programs (such as IMAP daemons) must lock the mailbox in an
8135 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8136 be combined with dot locking. To avoid deadlocks, a program
8137 should use <tt>fcntl()</tt> first and dot locking after
8138 this, or alternatively implement the two locking methods in
8139 a non blocking way<footnote>
8140 If it is not possible to establish both locks, the
8141 system shouldn't wait for the second lock to be
8142 established, but remove the first lock, wait a (random)
8143 time, and start over locking again.
8144 </footnote>. Using the functions <tt>maillock</tt> and
8145 <tt>mailunlock</tt> provided by the
8146 <tt>liblockfile*</tt><footnote>
8147 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8148 to use these functions.
8149 </footnote> packages is the recommended way to realize this.
8153 Mailboxes are generally either mode 600 and owned by
8154 <var>user</var> or mode 660 and owned by
8155 <tt><var>user</var>:mail</tt><footnote>
8156 There are two traditional permission schemes for mail spools:
8157 mode 600 with all mail delivery done by processes running as
8158 the destination user, or mode 660 and owned by group mail with
8159 mail delivery done by a process running as a system user in
8160 group mail. Historically, Debian required mode 660 mail
8161 spools to enable the latter model, but that model has become
8162 increasingly uncommon and the principle of least privilege
8163 indicates that mail systems that use the first model should
8164 use permissions of 600. If delivery to programs is permitted,
8165 it's easier to keep the mail system secure if the delivery
8166 agent runs as the destination user. Debian Policy therefore
8167 permits either scheme.
8168 </footnote>. The local system administrator may choose a
8169 different permission scheme; packages should not make
8170 assumptions about the permission and ownership of mailboxes
8171 unless required (such as when creating a new mailbox). A MUA
8172 may remove a mailbox (unless it has nonstandard permissions) in
8173 which case the MTA or another MUA must recreate it if needed.
8177 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8178 be setgid mail to do the locking mentioned above (and
8179 must obviously avoid accessing other users' mailboxes
8180 using this privilege).</p>
8183 <file>/etc/aliases</file> is the source file for the system mail
8184 aliases (e.g., postmaster, usenet, etc.), it is the one
8185 which the sysadmin and <prgn>postinst</prgn> scripts may
8186 edit. After <file>/etc/aliases</file> is edited the program or
8187 human editing it must call <prgn>newaliases</prgn>. All MTA
8188 packages must come with a <prgn>newaliases</prgn> program,
8189 even if it does nothing, but older MTA packages did not do
8190 this so programs should not fail if <prgn>newaliases</prgn>
8191 cannot be found. Note that because of this, all MTA
8192 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8193 <tt>Replaces: mail-transport-agent</tt> control file
8198 The convention of writing <tt>forward to
8199 <var>address</var></tt> in the mailbox itself is not
8200 supported. Use a <tt>.forward</tt> file instead.</p>
8203 The <prgn>rmail</prgn> program used by UUCP
8204 for incoming mail should be <file>/usr/sbin/rmail</file>.
8205 Likewise, <prgn>rsmtp</prgn>, for receiving
8206 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8210 If your package needs to know what hostname to use on (for
8211 example) outgoing news and mail messages which are generated
8212 locally, you should use the file <file>/etc/mailname</file>. It
8213 will contain the portion after the username and <tt>@</tt>
8214 (at) sign for email addresses of users on the machine
8215 (followed by a newline).
8219 Such a package should check for the existence of this file
8220 when it is being configured. If it exists, it should be
8221 used without comment, although an MTA's configuration script
8222 may wish to prompt the user even if it finds that this file
8223 exists. If the file does not exist, the package should
8224 prompt the user for the value (preferably using
8225 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8226 as well as using it in the package's configuration. The
8227 prompt should make it clear that the name will not just be
8228 used by that package. For example, in this situation the
8229 <tt>inn</tt> package could say something like:
8230 <example compact="compact">
8231 Please enter the "mail name" of your system. This is the
8232 hostname portion of the address to be shown on outgoing
8233 news and mail messages. The default is
8234 <var>syshostname</var>, your system's host name. Mail
8235 name ["<var>syshostname</var>"]:
8237 where <var>syshostname</var> is the output of <tt>hostname
8243 <heading>News system configuration</heading>
8246 All the configuration files related to the NNTP (news)
8247 servers and clients should be located under
8248 <file>/etc/news</file>.</p>
8251 There are some configuration issues that apply to a number
8252 of news clients and server packages on the machine. These
8256 <tag><file>/etc/news/organization</file></tag>
8258 A string which should appear as the
8259 organization header for all messages posted
8260 by NNTP clients on the machine
8263 <tag><file>/etc/news/server</file></tag>
8265 Contains the FQDN of the upstream NNTP
8266 server, or localhost if the local machine is
8271 Other global files may be added as required for cross-package news
8278 <heading>Programs for the X Window System</heading>
8281 <heading>Providing X support and package priorities</heading>
8284 Programs that can be configured with support for the X
8285 Window System must be configured to do so and must declare
8286 any package dependencies necessary to satisfy their
8287 runtime requirements when using the X Window System. If
8288 such a package is of higher priority than the X packages
8289 on which it depends, it is required that either the
8290 X-specific components be split into a separate package, or
8291 that an alternative version of the package, which includes
8292 X support, be provided, or that the package's priority be
8298 <heading>Packages providing an X server</heading>
8301 Packages that provide an X server that, directly or
8302 indirectly, communicates with real input and display
8303 hardware should declare in their control data that they
8304 provide the virtual package <tt>xserver</tt>.<footnote>
8305 This implements current practice, and provides an
8306 actual policy for usage of the <tt>xserver</tt>
8307 virtual package which appears in the virtual packages
8308 list. In a nutshell, X servers that interface
8309 directly with the display and input hardware or via
8310 another subsystem (e.g., GGI) should provide
8311 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8312 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8318 <heading>Packages providing a terminal emulator</heading>
8321 Packages that provide a terminal emulator for the X Window
8322 System which meet the criteria listed below should declare
8323 in their control data that they provide the virtual
8324 package <tt>x-terminal-emulator</tt>. They should also
8325 register themselves as an alternative for
8326 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8331 To be an <tt>x-terminal-emulator</tt>, a program must:
8332 <list compact="compact">
8334 Be able to emulate a DEC VT100 terminal, or a
8335 compatible terminal.
8339 Support the command-line option <tt>-e
8340 <var>command</var></tt>, which creates a new
8341 terminal window<footnote>
8342 "New terminal window" does not necessarily mean
8343 a new top-level X window directly parented by
8344 the window manager; it could, if the terminal
8345 emulator application were so coded, be a new
8346 "view" in a multiple-document interface (MDI).
8348 and runs the specified <var>command</var>,
8349 interpreting the entirety of the rest of the command
8350 line as a command to pass straight to exec, in the
8351 manner that <tt>xterm</tt> does.
8355 Support the command-line option <tt>-T
8356 <var>title</var></tt>, which creates a new terminal
8357 window with the window title <var>title</var>.
8364 <heading>Packages providing a window manager</heading>
8367 Packages that provide a window manager should declare in
8368 their control data that they provide the virtual package
8369 <tt>x-window-manager</tt>. They should also register
8370 themselves as an alternative for
8371 <file>/usr/bin/x-window-manager</file>, with a priority
8372 calculated as follows:
8373 <list compact="compact">
8375 Start with a priority of 20.
8379 If the window manager supports the Debian menu
8380 system, add 20 points if this support is available
8381 in the package's default configuration (i.e., no
8382 configuration files belonging to the system or user
8383 have to be edited to activate the feature); if
8384 configuration files must be modified, add only 10
8390 If the window manager complies with <url
8391 id="http://www.freedesktop.org/Standards/wm-spec"
8392 name="The Window Manager Specification Project">,
8393 written by the <url id="http://www.freedesktop.org/"
8394 name="Free Desktop Group">, add 40 points.
8398 If the window manager permits the X session to be
8399 restarted using a <em>different</em> window manager
8400 (without killing the X server) in its default
8401 configuration, add 10 points; otherwise add none.
8408 <heading>Packages providing fonts</heading>
8411 Packages that provide fonts for the X Window
8413 For the purposes of Debian Policy, a "font for the X
8414 Window System" is one which is accessed via X protocol
8415 requests. Fonts for the Linux console, for PostScript
8416 renderer, or any other purpose, do not fit this
8417 definition. Any tool which makes such fonts available
8418 to the X Window System, however, must abide by this
8421 must do a number of things to ensure that they are both
8422 available without modification of the X or font server
8423 configuration, and that they do not corrupt files used by
8424 other font packages to register information about
8428 Fonts of any type supported by the X Window System
8429 must be in a separate binary package from any
8430 executables, libraries, or documentation (except
8431 that specific to the fonts shipped, such as their
8432 license information). If one or more of the fonts
8433 so packaged are necessary for proper operation of
8434 the package with which they are associated the font
8435 package may be Recommended; if the fonts merely
8436 provide an enhancement, a Suggests relationship may
8437 be used. Packages must not Depend on font
8439 This is because the X server may retrieve fonts
8440 from the local file system or over the network
8441 from an X font server; the Debian package system
8442 is empowered to deal only with the local
8448 BDF fonts must be converted to PCF fonts with the
8449 <prgn>bdftopcf</prgn> utility (available in the
8450 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8451 placed in a directory that corresponds to their
8453 <list compact="compact">
8455 100 dpi fonts must be placed in
8456 <file>/usr/share/fonts/X11/100dpi/</file>.
8460 75 dpi fonts must be placed in
8461 <file>/usr/share/fonts/X11/75dpi/</file>.
8465 Character-cell fonts, cursor fonts, and other
8466 low-resolution fonts must be placed in
8467 <file>/usr/share/fonts/X11/misc/</file>.
8473 Type 1 fonts must be placed in
8474 <file>/usr/share/fonts/X11/Type1/</file>. If font
8475 metric files are available, they must be placed here
8480 Subdirectories of <file>/usr/share/fonts/X11/</file>
8481 other than those listed above must be neither
8482 created nor used. (The <file>PEX</file>, <file>CID</file>,
8483 <file>Speedo</file>, and <file>cyrillic</file> directories
8484 are excepted for historical reasons, but installation of
8485 files into these directories remains discouraged.)
8489 Font packages may, instead of placing files directly
8490 in the X font directories listed above, provide
8491 symbolic links in that font directory pointing to
8492 the files' actual location in the filesystem. Such
8493 a location must comply with the FHS.
8497 Font packages should not contain both 75dpi and
8498 100dpi versions of a font. If both are available,
8499 they should be provided in separate binary packages
8500 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8501 the names of the packages containing the
8502 corresponding fonts.
8506 Fonts destined for the <file>misc</file> subdirectory
8507 should not be included in the same package as 75dpi
8508 or 100dpi fonts; instead, they should be provided in
8509 a separate package with <tt>-misc</tt> appended to
8514 Font packages must not provide the files
8515 <file>fonts.dir</file>, <file>fonts.alias</file>, or
8516 <file>fonts.scale</file> in a font directory:
8519 <file>fonts.dir</file> files must not be provided at all.
8523 <file>fonts.alias</file> and <file>fonts.scale</file>
8524 files, if needed, should be provided in the
8526 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
8527 where <var>fontdir</var> is the name of the
8529 <file>/usr/share/fonts/X11/</file> where the
8530 package's corresponding fonts are stored
8531 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
8532 <var>package</var> is the name of the package
8533 that provides these fonts, and
8534 <var>extension</var> is either <tt>scale</tt>
8535 or <tt>alias</tt>, whichever corresponds to
8542 Font packages must declare a dependency on
8543 <tt>xfonts-utils</tt> in their control
8548 Font packages that provide one or more
8549 <file>fonts.scale</file> files as described above must
8550 invoke <prgn>update-fonts-scale</prgn> on each
8551 directory into which they installed fonts
8552 <em>before</em> invoking
8553 <prgn>update-fonts-dir</prgn> on that directory.
8554 This invocation must occur in both the
8555 <prgn>postinst</prgn> (for all arguments) and
8556 <prgn>postrm</prgn> (for all arguments except
8557 <tt>upgrade</tt>) scripts.
8561 Font packages that provide one or more
8562 <file>fonts.alias</file> files as described above must
8563 invoke <prgn>update-fonts-alias</prgn> on each
8564 directory into which they installed fonts. This
8565 invocation must occur in both the
8566 <prgn>postinst</prgn> (for all arguments) and
8567 <prgn>postrm</prgn> (for all arguments except
8568 <tt>upgrade</tt>) scripts.
8572 Font packages must invoke
8573 <prgn>update-fonts-dir</prgn> on each directory into
8574 which they installed fonts. This invocation must
8575 occur in both the <prgn>postinst</prgn> (for all
8576 arguments) and <prgn>postrm</prgn> (for all
8577 arguments except <tt>upgrade</tt>) scripts.
8581 Font packages must not provide alias names for the
8582 fonts they include which collide with alias names
8583 already in use by fonts already packaged.
8587 Font packages must not provide fonts with the same
8588 XLFD registry name as another font already packaged.
8594 <sect1 id="appdefaults">
8595 <heading>Application defaults files</heading>
8598 Application defaults files must be installed in the
8599 directory <file>/etc/X11/app-defaults/</file> (use of a
8600 localized subdirectory of <file>/etc/X11/</file> as described
8601 in the <em>X Toolkit Intrinsics - C Language
8602 Interface</em> manual is also permitted). They must be
8603 registered as <tt>conffile</tt>s or handled as
8604 configuration files.
8608 Customization of programs' X resources may also be
8609 supported with the provision of a file with the same name
8610 as that of the package placed in the
8611 <file>/etc/X11/Xresources/</file> directory, which must
8612 registered as a <tt>conffile</tt> or handled as a
8613 configuration file.<footnote>
8614 Note that this mechanism is not the same as using
8615 app-defaults; app-defaults are tied to the client
8616 binary on the local file system, whereas X resources
8617 are stored in the X server and affect all connecting
8624 <heading>Installation directory issues</heading>
8627 Historically, packages using the X Window System used a
8628 separate set of installation directories from other packages.
8629 This practice has been discontinued and packages using the X
8630 Window System should now generally be installed in the same
8631 directories as any other package. Specifically, packages must
8632 not install files under the <file>/usr/X11R6/</file> directory
8633 and the <file>/usr/X11R6/</file> directory hierarchy should be
8634 regarded as obsolete.
8638 Include files previously installed under
8639 <file>/usr/X11R6/include/X11/</file> should be installed into
8640 <file>/usr/include/X11/</file>. For files previously
8641 installed into subdirectories of
8642 <file>/usr/X11R6/lib/X11/</file>, package maintainers should
8643 determine if subdirectories of <file>/usr/lib/</file> and
8644 <file>/usr/share/</file> can be used. If not, a subdirectory
8645 of <file>/usr/lib/X11/</file> should be used.
8649 Configuration files for window, display, or session managers
8650 or other applications that are tightly integrated with the X
8651 Window System may be placed in a subdirectory
8652 of <file>/etc/X11/</file> corresponding to the package name.
8653 Other X Window System applications should use
8654 the <file>/etc/</file> directory unless otherwise mandated by
8655 policy (such as for <ref id="appdefaults">).
8660 <heading>The OSF/Motif and OpenMotif libraries</heading>
8663 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8664 OpenMotif libraries</em><footnote>
8665 OSF/Motif and OpenMotif are collectively referred to as
8666 "Motif" in this policy document.
8668 should be compiled against and tested with LessTif (a free
8669 re-implementation of Motif) instead. If the maintainer
8670 judges that the program or programs do not work
8671 sufficiently well with LessTif to be distributed and
8672 supported, but do so when compiled against Motif, then two
8673 versions of the package should be created; one linked
8674 statically against Motif and with <tt>-smotif</tt>
8675 appended to the package name, and one linked dynamically
8676 against Motif and with <tt>-dmotif</tt> appended to the
8681 Both Motif-linked versions are dependent
8682 upon non-DFSG-compliant software and thus cannot be
8683 uploaded to the <em>main</em> distribution; if the
8684 software is itself DFSG-compliant it may be uploaded to
8685 the <em>contrib</em> distribution. While known existing
8686 versions of Motif permit unlimited redistribution of
8687 binaries linked against the library (whether statically or
8688 dynamically), it is the package maintainer's
8689 responsibility to determine whether this is permitted by
8690 the license of the copy of Motif in their possession.
8696 <heading>Perl programs and modules</heading>
8699 Perl programs and modules should follow the current Perl policy.
8703 The Perl policy can be found in the <tt>perl-policy</tt>
8704 files in the <tt>debian-policy</tt> package.
8705 It is also available from the Debian web mirrors at
8706 <tt><url name="/doc/packaging-manuals/perl-policy/"
8707 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8712 <heading>Emacs lisp programs</heading>
8715 Please refer to the "Debian Emacs Policy" for details of how to
8716 package emacs lisp programs.
8720 The Emacs policy is available in
8721 <file>debian-emacs-policy.gz</file> of the
8722 <package>emacsen-common</package> package.
8723 It is also available from the Debian web mirrors at
8724 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8725 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8730 <heading>Games</heading>
8733 The permissions on <file>/var/games</file> are mode 755, owner
8734 <tt>root</tt> and group <tt>root</tt>.
8738 Each game decides on its own security policy.</p>
8741 Games which require protected, privileged access to
8742 high-score files, saved games, etc., may be made
8743 set-<em>group</em>-id (mode 2755) and owned by
8744 <tt>root:games</tt>, and use files and directories with
8745 appropriate permissions (770 <tt>root:games</tt>, for
8746 example). They must not be made
8747 set-<em>user</em>-id, as this causes security problems. (If
8748 an attacker can subvert any set-user-id game they can
8749 overwrite the executable of any other, causing other players
8750 of these games to run a Trojan horse program. With a
8751 set-group-id game the attacker only gets access to less
8752 important game data, and if they can get at the other
8753 players' accounts at all it will take considerably more
8757 Some packages, for example some fortune cookie programs, are
8758 configured by the upstream authors to install with their
8759 data files or other static information made unreadable so
8760 that they can only be accessed through set-id programs
8761 provided. You should not do this in a Debian package: anyone can
8762 download the <file>.deb</file> file and read the data from it,
8763 so there is no point making the files unreadable. Not
8764 making the files unreadable also means that you don't have
8765 to make so many programs set-id, which reduces the risk of a
8769 As described in the FHS, binaries of games should be
8770 installed in the directory <file>/usr/games</file>. This also
8771 applies to games that use the X Window System. Manual pages
8772 for games (X and non-X games) should be installed in
8773 <file>/usr/share/man/man6</file>.</p>
8779 <heading>Documentation</heading>
8782 <heading>Manual pages</heading>
8785 You should install manual pages in <prgn>nroff</prgn> source
8786 form, in appropriate places under <file>/usr/share/man</file>.
8787 You should only use sections 1 to 9 (see the FHS for more
8788 details). You must not install a pre-formatted "cat page".
8792 Each program, utility, and function should have an
8793 associated manual page included in the same package. It is
8794 suggested that all configuration files also have a manual
8795 page included as well. Manual pages for protocols and other
8796 auxiliary things are optional.
8800 If no manual page is available, this is considered as a bug
8801 and should be reported to the Debian Bug Tracking System (the
8802 maintainer of the package is allowed to write this bug report
8803 themselves, if they so desire). Do not close the bug report
8804 until a proper man page is available.<footnote>
8805 It is not very hard to write a man page. See the
8806 <url id="http://www.schweikhardt.net/man_page_howto.html"
8807 name="Man-Page-HOWTO">,
8808 <manref name="man" section="7">, the examples
8809 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8810 the helper programs <prgn>help2man</prgn>, or the
8811 directory <file>/usr/share/doc/man-db/examples</file>.
8816 You may forward a complaint about a missing man page to the
8817 upstream authors, and mark the bug as forwarded in the
8818 Debian bug tracking system. Even though the GNU Project do
8819 not in general consider the lack of a man page to be a bug,
8820 we do; if they tell you that they don't consider it a bug
8821 you should leave the bug in our bug tracking system open
8826 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8830 If one man page needs to be accessible via several names it
8831 is better to use a symbolic link than the <file>.so</file>
8832 feature, but there is no need to fiddle with the relevant
8833 parts of the upstream source to change from <file>.so</file> to
8834 symlinks: don't do it unless it's easy. You should not
8835 create hard links in the manual page directories, nor put
8836 absolute filenames in <file>.so</file> directives. The filename
8837 in a <file>.so</file> in a man page should be relative to the
8838 base of the man page tree (usually
8839 <file>/usr/share/man</file>). If you do not create any links
8840 (whether symlinks, hard links, or <tt>.so</tt> directives)
8841 in the file system to the alternate names of the man page,
8842 then you should not rely on <prgn>man</prgn> finding your
8843 man page under those names based solely on the information in
8844 the man page's header.<footnote>
8845 Supporting this in <prgn>man</prgn> often requires
8846 unreasonable processing time to find a manual page or to
8847 report that none exists, and moves knowledge into man's
8848 database that would be better left in the file system.
8849 This support is therefore deprecated and will cease to
8850 be present in the future.
8855 Manual pages in locale-specific subdirectories of
8856 <file>/usr/share/man</file> should use either UTF-8 or the usual
8857 legacy encoding for that language (normally the one corresponding
8858 to the shortest relevant locale name in
8859 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
8860 <file>/usr/share/man/fr</file> should use either UTF-8 or
8861 ISO-8859-1.<footnote>
8862 <prgn>man</prgn> will automatically detect whether UTF-8 is in
8863 use. In future, all manual pages will be required to use
8869 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
8870 included in the subdirectory name unless it indicates a
8871 significant difference in the language, as this excludes
8872 speakers of the language in other countries.<footnote>
8873 At the time of writing, Chinese and Portuguese are the main
8874 languages with such differences, so <file>pt_BR</file>,
8875 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
8880 If a localized version of a manual page is provided, it should
8881 either be up-to-date or it should be obvious to the reader that
8882 it is outdated and the original manual page should be used
8883 instead. This can be done either by a note at the beginning of
8884 the manual page or by showing the missing or changed portions in
8885 the original language instead of the target language.
8890 <heading>Info documents</heading>
8893 Info documents should be installed in <file>/usr/share/info</file>.
8894 They should be compressed with <tt>gzip -9</tt>.
8898 The <prgn>install-info</prgn> program maintains a directory of
8899 installed info documents in <file>/usr/share/info/dir</file> for
8900 the use of info readers.<footnote>
8901 It was previously necessary for packages installing info
8902 documents to run <prgn>install-info</prgn> from maintainer
8903 scripts. This is no longer necessary. The installation
8904 system now uses dpkg triggers.
8906 This file must not be included in packages. Packages containing
8907 info documents should depend on <tt>dpkg (>= 1.15.4) |
8908 install-info</tt> to ensure that the directory file is properly
8909 rebuilt during partial upgrades from Debian 5.0 (lenny) and
8914 Info documents should contain section and directory entry
8915 information in the document for the use
8916 of <prgn>install-info</prgn>. The section should be specified
8917 via a line starting with <tt>INFO-DIR-SECTION</tt> followed by a
8918 space and the section of this info page. The directory entry or
8919 entries should be included between
8920 a <tt>START-INFO-DIR-ENTRY</tt> line and
8921 an <tt>END-INFO-DIR-ENTRY</tt> line. For example:
8923 INFO-DIR-SECTION Individual utilities
8924 START-INFO-DIR-ENTRY
8925 * example: (example). An example info directory entry.
8928 To determine which section to use, you should look
8929 at <file>/usr/share/info/dir</file> on your system and choose
8930 the most relevant (or create a new section if none of the
8931 current sections are relevant).<footnote>
8932 Normally, info documents are generated from Texinfo source.
8933 To include this information in the generated info document, if
8934 it is absent, add commands like:
8936 @dircategory Individual utilities
8938 * example: (example). An example info directory entry.
8941 to the Texinfo source of the document and ensure that the info
8942 documents are rebuilt from source during the package build.
8948 <heading>Additional documentation</heading>
8951 Any additional documentation that comes with the package may
8952 be installed at the discretion of the package maintainer.
8953 Plain text documentation should be installed in the directory
8954 <file>/usr/share/doc/<var>package</var></file>, where
8955 <var>package</var> is the name of the package, and
8956 compressed with <tt>gzip -9</tt> unless it is small.
8960 If a package comes with large amounts of documentation which
8961 many users of the package will not require you should create
8962 a separate binary package to contain it, so that it does not
8963 take up disk space on the machines of users who do not need
8964 or want it installed.</p>
8967 It is often a good idea to put text information files
8968 (<file>README</file>s, changelogs, and so forth) that come with
8969 the source package in <file>/usr/share/doc/<var>package</var></file>
8970 in the binary package. However, you don't need to install
8971 the instructions for building and installing the package, of
8975 Packages must not require the existence of any files in
8976 <file>/usr/share/doc/</file> in order to function
8978 The system administrator should be able to
8979 delete files in <file>/usr/share/doc/</file> without causing
8980 any programs to break.
8982 Any files that are referenced by programs but are also
8983 useful as stand alone documentation should be installed under
8984 <file>/usr/share/<var>package</var>/</file> with symbolic links from
8985 <file>/usr/share/doc/<var>package</var></file>.
8989 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8990 link to another directory in <file>/usr/share/doc</file> only if
8991 the two packages both come from the same source and the
8992 first package Depends on the second.<footnote>
8994 Please note that this does not override the section on
8995 changelog files below, so the file
8996 <file>/usr/share/<var>package</var>/changelog.Debian.gz</file>
8997 must refer to the changelog for the current version of
8998 <var>package</var> in question. In practice, this means
8999 that the sources of the target and the destination of the
9000 symlink must be the same (same source package and
9007 Former Debian releases placed all additional documentation
9008 in <file>/usr/doc/<var>package</var></file>. This has been
9009 changed to <file>/usr/share/doc/<var>package</var></file>,
9010 and packages must not put documentation in the directory
9011 <file>/usr/doc/<var>package</var></file>. <footnote>
9012 At this phase of the transition, we no longer require a
9013 symbolic link in <file>/usr/doc/</file>. At a later point,
9014 policy shall change to make the symbolic links a bug.
9020 <heading>Preferred documentation formats</heading>
9023 The unification of Debian documentation is being carried out
9027 If your package comes with extensive documentation in a
9028 markup format that can be converted to various other formats
9029 you should if possible ship HTML versions in a binary
9030 package, in the directory
9031 <file>/usr/share/doc/<var>appropriate-package</var></file> or
9032 its subdirectories.<footnote>
9033 The rationale: The important thing here is that HTML
9034 docs should be available in <em>some</em> package, not
9035 necessarily in the main binary package.
9040 Other formats such as PostScript may be provided at the
9041 package maintainer's discretion.
9045 <sect id="copyrightfile">
9046 <heading>Copyright information</heading>
9049 Every package must be accompanied by a verbatim copy of its
9050 copyright and distribution license in the file
9051 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
9052 file must neither be compressed nor be a symbolic link.
9056 In addition, the copyright file must say where the upstream
9057 sources (if any) were obtained. It should name the original
9058 authors of the package and the Debian maintainer(s) who were
9059 involved with its creation.
9063 Packages in the <em>contrib</em> or <em>non-free</em> archive
9064 areas should state in the copyright file that the package is not
9065 part of the Debian GNU/Linux distribution and briefly explain
9070 A copy of the file which will be installed in
9071 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9072 be in <file>debian/copyright</file> in the source package.
9076 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9077 link to another directory in <file>/usr/share/doc</file> only if
9078 the two packages both come from the same source and the
9079 first package Depends on the second. These rules are
9080 important because copyrights must be extractable by
9085 Packages distributed under the UCB BSD license, the Apache
9086 license (version 2.0), the Artistic license, the GNU GPL
9087 (version 2 or 3), the GNU LGPL (versions 2, 2.1, or 3), and the
9088 GNU FDL (versions 1.2 or 1.3) should refer to the corresponding
9089 files under <file>/usr/share/common-licenses</file>,<footnote>
9092 <file>/usr/share/common-licenses/BSD</file>,
9093 <file>/usr/share/common-licenses/Apache-2.0</file>,
9094 <file>/usr/share/common-licenses/Artistic</file>,
9095 <file>/usr/share/common-licenses/GPL-2</file>,
9096 <file>/usr/share/common-licenses/GPL-3</file>,
9097 <file>/usr/share/common-licenses/LGPL-2</file>,
9098 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9099 <file>/usr/share/common-licenses/LGPL-3</file>,
9100 <file>/usr/share/common-licenses/GFDL-1.2</file>, and
9101 <file>/usr/share/common-licenses/GFDL-1.3</file>
9104 </footnote> rather than quoting them in the copyright
9109 You should not use the copyright file as a general <file>README</file>
9110 file. If your package has such a file it should be
9111 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9112 <file>README.Debian</file> or some other appropriate place.</p>
9116 <heading>Examples</heading>
9119 Any examples (configurations, source files, whatever),
9120 should be installed in a directory
9121 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9122 files should not be referenced by any program: they're there
9123 for the benefit of the system administrator and users as
9124 documentation only. Architecture-specific example files
9125 should be installed in a directory
9126 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9128 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9129 latter directory itself may be a symbolic link to the
9134 If the purpose of a package is to provide examples, then the
9135 example files may be installed into
9136 <file>/usr/share/doc/<var>package</var></file>.
9140 <sect id="changelogs">
9141 <heading>Changelog files</heading>
9144 Packages that are not Debian-native must contain a
9145 compressed copy of the <file>debian/changelog</file> file from
9146 the Debian source tree in
9147 <file>/usr/share/doc/<var>package</var></file> with the name
9148 <file>changelog.Debian.gz</file>.
9152 If an upstream changelog is available, it should be accessible as
9153 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9154 plain text. If the upstream changelog is distributed in
9155 HTML, it should be made available in that form as
9156 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9157 and a plain text <file>changelog.gz</file> should be generated
9158 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9159 the upstream changelog files do not already conform to this
9160 naming convention, then this may be achieved either by
9161 renaming the files, or by adding a symbolic link, at the
9162 maintainer's discretion.<footnote>
9163 Rationale: People should not have to look in places for
9164 upstream changelogs merely because they are given
9165 different names or are distributed in HTML format.
9170 All of these files should be installed compressed using
9171 <tt>gzip -9</tt>, as they will become large with time even
9172 if they start out small.
9176 If the package has only one changelog which is used both as
9177 the Debian changelog and the upstream one because there is
9178 no separate upstream maintainer then that changelog should
9179 usually be installed as
9180 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9181 there is a separate upstream maintainer, but no upstream
9182 changelog, then the Debian changelog should still be called
9183 <file>changelog.Debian.gz</file>.
9187 For details about the format and contents of the Debian
9188 changelog file, please see <ref id="dpkgchangelog">.
9193 <appendix id="pkg-scope">
9194 <heading>Introduction and scope of these appendices</heading>
9197 These appendices are taken essentially verbatim from the
9198 now-deprecated Packaging Manual, version 3.2.1.0. They are
9199 the chapters which are likely to be of use to package
9200 maintainers and which have not already been included in the
9201 policy document itself. Most of these sections are very likely
9202 not relevant to policy; they should be treated as
9203 documentation for the packaging system. Please note that these
9204 appendices are included for convenience, and for historical
9205 reasons: they used to be part of policy package, and they have
9206 not yet been incorporated into dpkg documentation. However,
9207 they still have value, and hence they are presented here.
9211 They have not yet been checked to ensure that they are
9212 compatible with the contents of policy, and if there are any
9213 contradictions, the version in the main policy document takes
9214 precedence. The remaining chapters of the old Packaging
9215 Manual have also not been read in detail to ensure that there
9216 are not parts which have been left out. Both of these will be
9221 Certain parts of the Packaging manual were integrated into the
9222 Policy Manual proper, and removed from the appendices. Links
9223 have been placed from the old locations to the new ones.
9227 <prgn>dpkg</prgn> is a suite of programs for creating binary
9228 package files and installing and removing them on Unix
9230 <prgn>dpkg</prgn> is targeted primarily at Debian
9231 GNU/Linux, but may work on or be ported to other
9237 The binary packages are designed for the management of
9238 installed executable programs (usually compiled binaries) and
9239 their associated data, though source code examples and
9240 documentation are provided as part of some packages.</p>
9243 This manual describes the technical aspects of creating Debian
9244 binary packages (<file>.deb</file> files). It documents the
9245 behavior of the package management programs
9246 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9247 they interact with packages.</p>
9250 It also documents the interaction between
9251 <prgn>dselect</prgn>'s core and the access method scripts it
9252 uses to actually install the selected packages, and describes
9253 how to create a new access method.</p>
9256 This manual does not go into detail about the options and
9257 usage of the package building and installation tools. It
9258 should therefore be read in conjunction with those programs'
9263 The utility programs which are provided with <prgn>dpkg</prgn>
9264 for managing various system configuration and similar issues,
9265 such as <prgn>update-rc.d</prgn> and
9266 <prgn>install-info</prgn>, are not described in detail here -
9267 please see their man pages.
9271 It is assumed that the reader is reasonably familiar with the
9272 <prgn>dpkg</prgn> System Administrators' manual.
9273 Unfortunately this manual does not yet exist.
9277 The Debian version of the FSF's GNU hello program is provided
9278 as an example for people wishing to create Debian
9279 packages. The Debian <prgn>debmake</prgn> package is
9280 recommended as a very helpful tool in creating and maintaining
9281 Debian packages. However, while the tools and examples are
9282 helpful, they do not replace the need to read and follow the
9283 Policy and Programmer's Manual.</p>
9286 <appendix id="pkg-binarypkg">
9287 <heading>Binary packages (from old Packaging Manual)</heading>
9290 The binary package has two main sections. The first part
9291 consists of various control information files and scripts used
9292 by <prgn>dpkg</prgn> when installing and removing. See <ref
9293 id="pkg-controlarea">.
9297 The second part is an archive containing the files and
9298 directories to be installed.
9302 In the future binary packages may also contain other
9303 components, such as checksums and digital signatures. The
9304 format for the archive is described in full in the
9305 <file>deb(5)</file> man page.
9309 <sect id="pkg-bincreating"><heading>Creating package files -
9310 <prgn>dpkg-deb</prgn>
9314 All manipulation of binary package files is done by
9315 <prgn>dpkg-deb</prgn>; it's the only program that has
9316 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9317 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9318 will spot that the options requested are appropriate to
9319 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9324 In order to create a binary package you must make a
9325 directory tree which contains all the files and directories
9326 you want to have in the file system data part of the package.
9327 In Debian-format source packages this directory is usually
9328 <file>debian/tmp</file>, relative to the top of the package's
9333 They should have the locations (relative to the root of the
9334 directory tree you're constructing) ownerships and
9335 permissions which you want them to have on the system when
9340 With current versions of <prgn>dpkg</prgn> the uid/username
9341 and gid/groupname mappings for the users and groups being
9342 used should be the same on the system where the package is
9343 built and the one where it is installed.
9347 You need to add one special directory to the root of the
9348 miniature file system tree you're creating:
9349 <prgn>DEBIAN</prgn>. It should contain the control
9350 information files, notably the binary package control file
9351 (see <ref id="pkg-controlfile">).
9355 The <prgn>DEBIAN</prgn> directory will not appear in the
9356 file system archive of the package, and so won't be installed
9357 by <prgn>dpkg</prgn> when the package is installed.
9361 When you've prepared the package, you should invoke:
9363 dpkg --build <var>directory</var>
9368 This will build the package in
9369 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9370 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9371 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9376 See the man page <manref name="dpkg-deb" section="8"> for details of how
9377 to examine the contents of this newly-created file. You may find the
9378 output of following commands enlightening:
9380 dpkg-deb --info <var>filename</var>.deb
9381 dpkg-deb --contents <var>filename</var>.deb
9382 dpkg --contents <var>filename</var>.deb
9384 To view the copyright file for a package you could use this command:
9386 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
9391 <sect id="pkg-controlarea">
9392 <heading>Package control information files</heading>
9395 The control information portion of a binary package is a
9396 collection of files with names known to <prgn>dpkg</prgn>.
9397 It will treat the contents of these files specially - some
9398 of them contain information used by <prgn>dpkg</prgn> when
9399 installing or removing the package; others are scripts which
9400 the package maintainer wants <prgn>dpkg</prgn> to run.
9404 It is possible to put other files in the package control
9405 area, but this is not generally a good idea (though they
9406 will largely be ignored).
9410 Here is a brief list of the control info files supported by
9411 <prgn>dpkg</prgn> and a summary of what they're used for.
9416 <tag><tt>control</tt>
9419 This is the key description file used by
9420 <prgn>dpkg</prgn>. It specifies the package's name
9421 and version, gives its description for the user,
9422 states its relationships with other packages, and so
9423 forth. See <ref id="sourcecontrolfiles"> and
9424 <ref id="binarycontrolfiles">.
9428 It is usually generated automatically from information
9429 in the source package by the
9430 <prgn>dpkg-gencontrol</prgn> program, and with
9431 assistance from <prgn>dpkg-shlibdeps</prgn>.
9432 See <ref id="pkg-sourcetools">.
9436 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9441 These are executable files (usually scripts) which
9442 <prgn>dpkg</prgn> runs during installation, upgrade
9443 and removal of packages. They allow the package to
9444 deal with matters which are particular to that package
9445 or require more complicated processing than that
9446 provided by <prgn>dpkg</prgn>. Details of when and
9447 how they are called are in <ref id="maintainerscripts">.
9451 It is very important to make these scripts idempotent.
9452 See <ref id="idempotency">.
9456 The maintainer scripts are guaranteed to run with a
9457 controlling terminal and can interact with the user.
9458 See <ref id="controllingterminal">.
9462 <tag><tt>conffiles</tt>
9465 This file contains a list of configuration files which
9466 are to be handled automatically by <prgn>dpkg</prgn>
9467 (see <ref id="pkg-conffiles">). Note that not necessarily
9468 every configuration file should be listed here.
9471 <tag><tt>shlibs</tt>
9474 This file contains a list of the shared libraries
9475 supplied by the package, with dependency details for
9476 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9477 when it determines what dependencies are required in a
9478 package control file. The <tt>shlibs</tt> file format
9479 is described on <ref id="shlibs">.
9484 <sect id="pkg-controlfile">
9485 <heading>The main control information file: <tt>control</tt></heading>
9488 The most important control information file used by
9489 <prgn>dpkg</prgn> when it installs a package is
9490 <tt>control</tt>. It contains all the package's "vital
9495 The binary package control files of packages built from
9496 Debian sources are made by a special tool,
9497 <prgn>dpkg-gencontrol</prgn>, which reads
9498 <file>debian/control</file> and <file>debian/changelog</file> to
9499 find the information it needs. See <ref id="pkg-sourcepkg"> for
9504 The fields in binary package control files are listed in
9505 <ref id="binarycontrolfiles">.
9509 A description of the syntax of control files and the purpose
9510 of the fields is available in <ref id="controlfields">.
9515 <heading>Time Stamps</heading>
9518 See <ref id="timestamps">.
9523 <appendix id="pkg-sourcepkg">
9524 <heading>Source packages (from old Packaging Manual) </heading>
9527 The Debian binary packages in the distribution are generated
9528 from Debian sources, which are in a special format to assist
9529 the easy and automatic building of binaries.
9532 <sect id="pkg-sourcetools">
9533 <heading>Tools for processing source packages</heading>
9536 Various tools are provided for manipulating source packages;
9537 they pack and unpack sources and help build of binary
9538 packages and help manage the distribution of new versions.
9542 They are introduced and typical uses described here; see
9543 <manref name="dpkg-source" section="1"> for full
9544 documentation about their arguments and operation.
9548 For examples of how to construct a Debian source package,
9549 and how to use those utilities that are used by Debian
9550 source packages, please see the <prgn>hello</prgn> example
9554 <sect1 id="pkg-dpkg-source">
9556 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
9561 This program is frequently used by hand, and is also
9562 called from package-independent automated building scripts
9563 such as <prgn>dpkg-buildpackage</prgn>.
9567 To unpack a package it is typically invoked with
9569 dpkg-source -x <var>.../path/to/filename</var>.dsc
9574 with the <file><var>filename</var>.tar.gz</file> and
9575 <file><var>filename</var>.diff.gz</file> (if applicable) in
9576 the same directory. It unpacks into
9577 <file><var>package</var>-<var>version</var></file>, and if
9579 <file><var>package</var>-<var>version</var>.orig</file>, in
9580 the current directory.
9584 To create a packed source archive it is typically invoked:
9586 dpkg-source -b <var>package</var>-<var>version</var>
9591 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
9592 <file>.diff.gz</file> (if appropriate) in the current
9593 directory. <prgn>dpkg-source</prgn> does not clean the
9594 source tree first - this must be done separately if it is
9599 See also <ref id="pkg-sourcearchives">.</p>
9603 <sect1 id="pkg-dpkg-buildpackage">
9605 <prgn>dpkg-buildpackage</prgn> - overall package-building
9610 <prgn>dpkg-buildpackage</prgn> is a script which invokes
9611 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
9612 targets <tt>clean</tt>, <tt>build</tt> and
9613 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
9614 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
9615 source and binary package upload.
9619 It is usually invoked by hand from the top level of the
9620 built or unbuilt source directory. It may be invoked with
9621 no arguments; useful arguments include:
9622 <taglist compact="compact">
9623 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
9626 Do not sign the <tt>.changes</tt> file or the
9627 source package <tt>.dsc</tt> file, respectively.</p>
9629 <tag><tt>-p<var>sign-command</var></tt></tag>
9632 Invoke <var>sign-command</var> instead of finding
9633 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
9634 <var>sign-command</var> must behave just like
9635 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9637 <tag><tt>-r<var>root-command</var></tt></tag>
9640 When root privilege is required, invoke the command
9641 <var>root-command</var>. <var>root-command</var>
9642 should invoke its first argument as a command, from
9643 the <prgn>PATH</prgn> if necessary, and pass its
9644 second and subsequent arguments to the command it
9645 calls. If no <var>root-command</var> is supplied
9646 then <var>dpkg-buildpackage</var> will take no
9647 special action to gain root privilege, so that for
9648 most packages it will have to be invoked as root to
9651 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9654 Two types of binary-only build and upload - see
9655 <manref name="dpkg-source" section="1">.
9662 <sect1 id="pkg-dpkg-gencontrol">
9664 <prgn>dpkg-gencontrol</prgn> - generates binary package
9669 This program is usually called from <file>debian/rules</file>
9670 (see <ref id="pkg-sourcetree">) in the top level of the source
9675 This is usually done just before the files and directories in the
9676 temporary directory tree where the package is being built have their
9677 permissions and ownerships set and the package is constructed using
9678 <prgn>dpkg-deb/</prgn>
9680 This is so that the control file which is produced has
9681 the right permissions
9686 <prgn>dpkg-gencontrol</prgn> must be called after all the
9687 files which are to go into the package have been placed in
9688 the temporary build directory, so that its calculation of
9689 the installed size of a package is correct.
9693 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9694 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9695 variable substitutions created by
9696 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9701 For a package which generates only one binary package, and
9702 which builds it in <file>debian/tmp</file> relative to the top
9703 of the source package, it is usually sufficient to call
9704 <prgn>dpkg-gencontrol</prgn>.
9708 Sources which build several binaries will typically need
9711 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9712 </example> The <tt>-P</tt> tells
9713 <prgn>dpkg-gencontrol</prgn> that the package is being
9714 built in a non-default directory, and the <tt>-p</tt>
9715 tells it which package's control file should be generated.
9719 <prgn>dpkg-gencontrol</prgn> also adds information to the
9720 list of files in <file>debian/files</file>, for the benefit of
9721 (for example) a future invocation of
9722 <prgn>dpkg-genchanges</prgn>.</p>
9725 <sect1 id="pkg-dpkg-shlibdeps">
9727 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9732 This program is usually called from <file>debian/rules</file>
9733 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9734 id="pkg-sourcetree">), in the top level of the source tree.
9738 Its arguments are executables and shared libraries
9741 They may be specified either in the locations in the
9742 source tree where they are created or in the locations
9743 in the temporary build tree where they are installed
9744 prior to binary package creation.
9746 </footnote> for which shared library dependencies should
9747 be included in the binary package's control file.
9751 If some of the found shared libraries should only
9752 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9753 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9754 by using the <tt>-d<var>dependency-field</var></tt> option
9755 before those executable(s). (Each <tt>-d</tt> option
9756 takes effect until the next <tt>-d</tt>.)
9760 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9761 output control file to be modified. Instead by default it
9762 adds to the <file>debian/substvars</file> file variable
9763 settings like <tt>shlibs:Depends</tt>. These variable
9764 settings must be referenced in dependency fields in the
9765 appropriate per-binary-package sections of the source
9770 For example, a package that generates an essential part
9771 which requires dependencies, and optional parts that
9772 which only require a recommendation, would separate those
9773 two sets of dependencies into two different fields.<footnote>
9774 At the time of writing, an example for this was the
9775 <package/xmms/ package, with Depends used for the xmms
9776 executable, Recommends for the plug-ins and Suggests for
9777 even more optional features provided by unzip.
9779 It can say in its <file>debian/rules</file>:
9781 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9782 -dRecommends <var>optionalpart anotheroptionalpart</var>
9784 and then in its main control file <file>debian/control</file>:
9787 Depends: ${shlibs:Depends}
9788 Recommends: ${shlibs:Recommends}
9794 Sources which produce several binary packages with
9795 different shared library dependency requirements can use
9796 the <tt>-p<var>varnameprefix</var></tt> option to override
9797 the default <tt>shlibs:</tt> prefix (one invocation of
9798 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9799 They can thus produce several sets of dependency
9800 variables, each of the form
9801 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9802 which can be referred to in the appropriate parts of the
9803 binary package control files.
9808 <sect1 id="pkg-dpkg-distaddfile">
9810 <prgn>dpkg-distaddfile</prgn> - adds a file to
9811 <file>debian/files</file>
9815 Some packages' uploads need to include files other than
9816 the source and binary package files.
9820 <prgn>dpkg-distaddfile</prgn> adds a file to the
9821 <file>debian/files</file> file so that it will be included in
9822 the <file>.changes</file> file when
9823 <prgn>dpkg-genchanges</prgn> is run.
9827 It is usually invoked from the <tt>binary</tt> target of
9828 <file>debian/rules</file>:
9830 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9832 The <var>filename</var> is relative to the directory where
9833 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9834 is usually the directory above the top level of the source
9835 tree. The <file>debian/rules</file> target should put the
9836 file there just before or just after calling
9837 <prgn>dpkg-distaddfile</prgn>.
9841 The <var>section</var> and <var>priority</var> are passed
9842 unchanged into the resulting <file>.changes</file> file.
9847 <sect1 id="pkg-dpkg-genchanges">
9849 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9854 This program is usually called by package-independent
9855 automatic building scripts such as
9856 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9861 It is usually called in the top level of a built source
9862 tree, and when invoked with no arguments will print out a
9863 straightforward <file>.changes</file> file based on the
9864 information in the source package's changelog and control
9865 file and the binary and source packages which should have
9871 <sect1 id="pkg-dpkg-parsechangelog">
9873 <prgn>dpkg-parsechangelog</prgn> - produces parsed
9874 representation of a changelog
9878 This program is used internally by
9879 <prgn>dpkg-source</prgn> et al. It may also occasionally
9880 be useful in <file>debian/rules</file> and elsewhere. It
9881 parses a changelog, <file>debian/changelog</file> by default,
9882 and prints a control-file format representation of the
9883 information in it to standard output.
9887 <sect1 id="pkg-dpkg-architecture">
9889 <prgn>dpkg-architecture</prgn> - information about the build and
9894 This program can be used manually, but is also invoked by
9895 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9896 environment or make variables which specify the build and host
9897 architecture for the package building process.
9902 <sect id="pkg-sourcetree">
9903 <heading>The Debianised source tree</heading>
9906 The source archive scheme described later is intended to
9907 allow a Debianised source tree with some associated control
9908 information to be reproduced and transported easily. The
9909 Debianised source tree is a version of the original program
9910 with certain files added for the benefit of the
9911 Debianisation process, and with any other changes required
9912 made to the rest of the source code and installation
9917 The extra files created for Debian are in the subdirectory
9918 <file>debian</file> of the top level of the Debianised source
9919 tree. They are described below.
9922 <sect1 id="pkg-debianrules">
9923 <heading><file>debian/rules</file> - the main building script</heading>
9926 See <ref id="debianrules">.
9931 <sect1 id="pkg-dpkgchangelog">
9932 <heading><file>debian/changelog</file></heading>
9935 See <ref id="dpkgchangelog">.
9938 <sect2><heading>Defining alternative changelog formats
9942 It is possible to use a different format to the standard
9943 one, by providing a parser for the format you wish to
9948 In order to have <tt>dpkg-parsechangelog</tt> run your
9949 parser, you must include a line within the last 40 lines
9950 of your file matching the Perl regular expression:
9951 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9952 parentheses should be the name of the format. For
9953 example, you might say:
9955 @@@ changelog-format: joebloggs @@@
9957 Changelog format names are non-empty strings of alphanumerics.
9961 If such a line exists then <tt>dpkg-parsechangelog</tt>
9962 will look for the parser as
9963 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9965 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9966 it is an error for it not to find it, or for it not to
9967 be an executable program. The default changelog format
9968 is <tt>dpkg</tt>, and a parser for it is provided with
9969 the <tt>dpkg</tt> package.
9973 The parser will be invoked with the changelog open on
9974 standard input at the start of the file. It should read
9975 the file (it may seek if it wishes) to determine the
9976 information required and return the parsed information
9977 to standard output in the form of a series of control
9978 fields in the standard format. By default it should
9979 return information about only the most recent version in
9980 the changelog; it should accept a
9981 <tt>-v<var>version</var></tt> option to return changes
9982 information from all versions present <em>strictly
9983 after</em> <var>version</var>, and it should then be an
9984 error for <var>version</var> not to be present in the
9990 <list compact="compact">
9991 <item><qref id="f-Source"><tt>Source</tt></qref></item>
9992 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
9993 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
9994 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
9995 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
9996 <item><qref id="f-Date"><tt>Date</tt></qref></item>
9997 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
10002 If several versions are being returned (due to the use
10003 of <tt>-v</tt>), the urgency value should be of the
10004 highest urgency code listed at the start of any of the
10005 versions requested followed by the concatenated
10006 (space-separated) comments from all the versions
10007 requested; the maintainer, version, distribution and
10008 date should always be from the most recent version.
10012 For the format of the <tt>Changes</tt> field see
10013 <ref id="f-Changes">.
10017 If the changelog format which is being parsed always or
10018 almost always leaves a blank line between individual
10019 change notes these blank lines should be stripped out,
10020 so as to make the resulting output compact.
10024 If the changelog format does not contain date or package
10025 name information this information should be omitted from
10026 the output. The parser should not attempt to synthesize
10027 it or find it from other sources.
10031 If the changelog does not have the expected format the
10032 parser should exit with a nonzero exit status, rather
10033 than trying to muddle through and possibly generating
10038 A changelog parser may not interact with the user at
10044 <sect1 id="pkg-srcsubstvars">
10045 <heading><file>debian/substvars</file> and variable substitutions</heading>
10048 See <ref id="substvars">.
10054 <heading><file>debian/files</file></heading>
10057 See <ref id="debianfiles">.
10061 <sect1><heading><file>debian/tmp</file>
10065 This is the canonical temporary location for the
10066 construction of binary packages by the <tt>binary</tt>
10067 target. The directory <file>tmp</file> serves as the root of
10068 the file system tree as it is being constructed (for
10069 example, by using the package's upstream makefiles install
10070 targets and redirecting the output there), and it also
10071 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10072 id="pkg-bincreating">.
10076 If several binary packages are generated from the same
10077 source tree it is usual to use several
10078 <file>debian/tmp<var>something</var></file> directories, for
10079 example <file>tmp-a</file> or <file>tmp-doc</file>.
10083 Whatever <file>tmp</file> directories are created and used by
10084 <tt>binary</tt> must of course be removed by the
10085 <tt>clean</tt> target.</p></sect1>
10089 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10093 As it exists on the FTP site, a Debian source package
10094 consists of three related files. You must have the right
10095 versions of all three to be able to use them.
10100 <tag>Debian source control file - <tt>.dsc</tt></tag>
10102 This file is a control file used by <prgn>dpkg-source</prgn>
10103 to extract a source package.
10104 See <ref id="debiansourcecontrolfiles">.
10108 Original source archive -
10110 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10116 This is a compressed (with <tt>gzip -9</tt>)
10117 <prgn>tar</prgn> file containing the source code from
10118 the upstream authors of the program.
10123 Debianisation diff -
10125 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10131 This is a unified context diff (<tt>diff -u</tt>)
10132 giving the changes which are required to turn the
10133 original source into the Debian source. These changes
10134 may only include editing and creating plain files.
10135 The permissions of files, the targets of symbolic
10136 links and the characteristics of special files or
10137 pipes may not be changed and no files may be removed
10142 All the directories in the diff must exist, except the
10143 <file>debian</file> subdirectory of the top of the source
10144 tree, which will be created by
10145 <prgn>dpkg-source</prgn> if necessary when unpacking.
10149 The <prgn>dpkg-source</prgn> program will
10150 automatically make the <file>debian/rules</file> file
10151 executable (see below).</p></item>
10156 If there is no original source code - for example, if the
10157 package is specially prepared for Debian or the Debian
10158 maintainer is the same as the upstream maintainer - the
10159 format is slightly different: then there is no diff, and the
10161 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10162 and preferably contains a directory named
10163 <file><var>package</var>-<var>version</var></file>.
10168 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10171 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10172 Debian source package. However, if it is not available it
10173 is possible to unpack a Debian source archive as follows:
10174 <enumlist compact="compact">
10177 Untar the tarfile, which will create a <file>.orig</file>
10181 <p>Rename the <file>.orig</file> directory to
10182 <file><var>package</var>-<var>version</var></file>.</p>
10186 Create the subdirectory <file>debian</file> at the top of
10187 the source tree.</p>
10189 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10191 <item><p>Untar the tarfile again if you want a copy of the original
10192 source code alongside the Debianised version.</p>
10197 It is not possible to generate a valid Debian source archive
10198 without using <prgn>dpkg-source</prgn>. In particular,
10199 attempting to use <prgn>diff</prgn> directly to generate the
10200 <file>.diff.gz</file> file will not work.
10204 <heading>Restrictions on objects in source packages</heading>
10207 The source package may not contain any hard links
10209 This is not currently detected when building source
10210 packages, but only when extracting
10214 Hard links may be permitted at some point in the
10215 future, but would require a fair amount of
10217 </footnote>, device special files, sockets or setuid or
10220 Setgid directories are allowed.
10225 The source packaging tools manage the changes between the
10226 original and Debianised source using <prgn>diff</prgn> and
10227 <prgn>patch</prgn>. Turning the original source tree as
10228 included in the <file>.orig.tar.gz</file> into the debianised
10229 source must not involve any changes which cannot be
10230 handled by these tools. Problematic changes which cause
10231 <prgn>dpkg-source</prgn> to halt with an error when
10232 building the source package are:
10233 <list compact="compact">
10234 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10236 <item><p>Changing the targets of symbolic links.</p>
10238 <item><p>Creating directories, other than <file>debian</file>.</p>
10240 <item><p>Changes to the contents of binary files.</p></item>
10241 </list> Changes which cause <prgn>dpkg-source</prgn> to
10242 print a warning but continue anyway are:
10243 <list compact="compact">
10246 Removing files, directories or symlinks.
10248 Renaming a file is not treated specially - it is
10249 seen as the removal of the old file (which
10250 generates a warning, but is otherwise ignored),
10251 and the creation of the new one.
10257 Changed text files which are missing the usual final
10258 newline (either in the original or the modified
10263 Changes which are not represented, but which are not detected by
10264 <prgn>dpkg-source</prgn>, are:
10265 <list compact="compact">
10266 <item><p>Changing the permissions of files (other than
10267 <file>debian/rules</file>) and directories.</p></item>
10272 The <file>debian</file> directory and <file>debian/rules</file>
10273 are handled specially by <prgn>dpkg-source</prgn> - before
10274 applying the changes it will create the <file>debian</file>
10275 directory, and afterwards it will make
10276 <file>debian/rules</file> world-executable.
10282 <appendix id="pkg-controlfields">
10283 <heading>Control files and their fields (from old Packaging Manual)</heading>
10286 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10287 data in a common format, known as control files. Binary and
10288 source packages have control data as do the <file>.changes</file>
10289 files which control the installation of uploaded files, and
10290 <prgn>dpkg</prgn>'s internal databases are in a similar
10295 <heading>Syntax of control files</heading>
10298 See <ref id="controlsyntax">.
10302 It is important to note that there are several fields which
10303 are optional as far as <prgn>dpkg</prgn> and the related
10304 tools are concerned, but which must appear in every Debian
10305 package, or whose omission may cause problems.
10310 <heading>List of fields</heading>
10313 See <ref id="controlfieldslist">.
10317 This section now contains only the fields that didn't belong
10318 to the Policy manual.
10321 <sect1 id="pkg-f-Filename">
10322 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10325 These fields in <tt>Packages</tt> files give the
10326 filename(s) of (the parts of) a package in the
10327 distribution directories, relative to the root of the
10328 Debian hierarchy. If the package has been split into
10329 several parts the parts are all listed in order, separated
10334 <sect1 id="pkg-f-Size">
10335 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10338 These fields in <file>Packages</file> files give the size (in
10339 bytes, expressed in decimal) and MD5 checksum of the
10340 file(s) which make(s) up a binary package in the
10341 distribution. If the package is split into several parts
10342 the values for the parts are listed in order, separated by
10347 <sect1 id="pkg-f-Status">
10348 <heading><tt>Status</tt></heading>
10351 This field in <prgn>dpkg</prgn>'s status file records
10352 whether the user wants a package installed, removed or
10353 left alone, whether it is broken (requiring
10354 re-installation) or not and what its current state on the
10355 system is. Each of these pieces of information is a
10360 <sect1 id="pkg-f-Config-Version">
10361 <heading><tt>Config-Version</tt></heading>
10364 If a package is not installed or not configured, this
10365 field in <prgn>dpkg</prgn>'s status file records the last
10366 version of the package which was successfully
10371 <sect1 id="pkg-f-Conffiles">
10372 <heading><tt>Conffiles</tt></heading>
10375 This field in <prgn>dpkg</prgn>'s status file contains
10376 information about the automatically-managed configuration
10377 files held by a package. This field should <em>not</em>
10378 appear anywhere in a package!
10383 <heading>Obsolete fields</heading>
10386 These are still recognized by <prgn>dpkg</prgn> but should
10387 not appear anywhere any more.
10389 <taglist compact="compact">
10391 <tag><tt>Revision</tt></tag>
10392 <tag><tt>Package-Revision</tt></tag>
10393 <tag><tt>Package_Revision</tt></tag>
10395 The Debian revision part of the package version was
10396 at one point in a separate control file field. This
10397 field went through several names.
10400 <tag><tt>Recommended</tt></tag>
10401 <item>Old name for <tt>Recommends</tt>.</item>
10403 <tag><tt>Optional</tt></tag>
10404 <item>Old name for <tt>Suggests</tt>.</item>
10406 <tag><tt>Class</tt></tag>
10407 <item>Old name for <tt>Priority</tt>.</item>
10416 <appendix id="pkg-conffiles">
10417 <heading>Configuration file handling (from old Packaging Manual)</heading>
10420 <prgn>dpkg</prgn> can do a certain amount of automatic
10421 handling of package configuration files.
10425 Whether this mechanism is appropriate depends on a number of
10426 factors, but basically there are two approaches to any
10427 particular configuration file.
10431 The easy method is to ship a best-effort configuration in the
10432 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10433 handle updates. If the user is unlikely to want to edit the
10434 file, but you need them to be able to without losing their
10435 changes, and a new package with a changed version of the file
10436 is only released infrequently, this is a good approach.
10440 The hard method is to build the configuration file from
10441 scratch in the <prgn>postinst</prgn> script, and to take the
10442 responsibility for fixing any mistakes made in earlier
10443 versions of the package automatically. This will be
10444 appropriate if the file is likely to need to be different on
10448 <sect><heading>Automatic handling of configuration files by
10453 A package may contain a control area file called
10454 <tt>conffiles</tt>. This file should be a list of filenames
10455 of configuration files needing automatic handling, separated
10456 by newlines. The filenames should be absolute pathnames,
10457 and the files referred to should actually exist in the
10462 When a package is upgraded <prgn>dpkg</prgn> will process
10463 the configuration files during the configuration stage,
10464 shortly before it runs the package's <prgn>postinst</prgn>
10469 For each file it checks to see whether the version of the
10470 file included in the package is the same as the one that was
10471 included in the last version of the package (the one that is
10472 being upgraded from); it also compares the version currently
10473 installed on the system with the one shipped with the last
10478 If neither the user nor the package maintainer has changed
10479 the file, it is left alone. If one or the other has changed
10480 their version, then the changed version is preferred - i.e.,
10481 if the user edits their file, but the package maintainer
10482 doesn't ship a different version, the user's changes will
10483 stay, silently, but if the maintainer ships a new version
10484 and the user hasn't edited it the new version will be
10485 installed (with an informative message). If both have
10486 changed their version the user is prompted about the problem
10487 and must resolve the differences themselves.
10491 The comparisons are done by calculating the MD5 message
10492 digests of the files, and storing the MD5 of the file as it
10493 was included in the most recent version of the package.
10497 When a package is installed for the first time
10498 <prgn>dpkg</prgn> will install the file that comes with it,
10499 unless that would mean overwriting a file already on the
10504 However, note that <prgn>dpkg</prgn> will <em>not</em>
10505 replace a conffile that was removed by the user (or by a
10506 script). This is necessary because with some programs a
10507 missing file produces an effect hard or impossible to
10508 achieve in another way, so that a missing file needs to be
10509 kept that way if the user did it.
10513 Note that a package should <em>not</em> modify a
10514 <prgn>dpkg</prgn>-handled conffile in its maintainer
10515 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10516 the user confusing and possibly dangerous options for
10517 conffile update when the package is upgraded.</p>
10520 <sect><heading>Fully-featured maintainer script configuration
10525 For files which contain site-specific information such as
10526 the hostname and networking details and so forth, it is
10527 better to create the file in the package's
10528 <prgn>postinst</prgn> script.
10532 This will typically involve examining the state of the rest
10533 of the system to determine values and other information, and
10534 may involve prompting the user for some information which
10535 can't be obtained some other way.
10539 When using this method there are a couple of important
10540 issues which should be considered:
10544 If you discover a bug in the program which generates the
10545 configuration file, or if the format of the file changes
10546 from one version to the next, you will have to arrange for
10547 the postinst script to do something sensible - usually this
10548 will mean editing the installed configuration file to remove
10549 the problem or change the syntax. You will have to do this
10550 very carefully, since the user may have changed the file,
10551 perhaps to fix the very problem that your script is trying
10552 to deal with - you will have to detect these situations and
10553 deal with them correctly.
10557 If you do go down this route it's probably a good idea to
10558 make the program that generates the configuration file(s) a
10559 separate program in <file>/usr/sbin</file>, by convention called
10560 <file><var>package</var>config</file> and then run that if
10561 appropriate from the post-installation script. The
10562 <tt><var>package</var>config</tt> program should not
10563 unquestioningly overwrite an existing configuration - if its
10564 mode of operation is geared towards setting up a package for
10565 the first time (rather than any arbitrary reconfiguration
10566 later) you should have it check whether the configuration
10567 already exists, and require a <tt>--force</tt> flag to
10568 overwrite it.</p></sect>
10571 <appendix id="pkg-alternatives"><heading>Alternative versions of
10572 an interface - <prgn>update-alternatives</prgn> (from old
10577 When several packages all provide different versions of the
10578 same program or file it is useful to have the system select a
10579 default, but to allow the system administrator to change it
10580 and have their decisions respected.
10584 For example, there are several versions of the <prgn>vi</prgn>
10585 editor, and there is no reason to prevent all of them from
10586 being installed at once, each under their own name
10587 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10588 Nevertheless it is desirable to have the name <tt>vi</tt>
10589 refer to something, at least by default.
10593 If all the packages involved cooperate, this can be done with
10594 <prgn>update-alternatives</prgn>.
10598 Each package provides its own version under its own name, and
10599 calls <prgn>update-alternatives</prgn> in its postinst to
10600 register its version (and again in its prerm to deregister
10605 See the man page <manref name="update-alternatives"
10606 section="8"> for details.
10610 If <prgn>update-alternatives</prgn> does not seem appropriate
10611 you may wish to consider using diversions instead.</p>
10614 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10615 package's version of a file (from old Packaging Manual)
10619 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10620 when it reinstalls the package it belongs to, and to have it
10621 put the file from the package somewhere else instead.
10625 This can be used locally to override a package's version of a
10626 file, or by one package to override another's version (or
10627 provide a wrapper for it).
10631 Before deciding to use a diversion, read <ref
10632 id="pkg-alternatives"> to see if you really want a diversion
10633 rather than several alternative versions of a program.
10637 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10638 and updated by a special program <prgn>dpkg-divert</prgn>.
10639 Please see <manref name="dpkg-divert" section="8"> for full
10640 details of its operation.
10644 When a package wishes to divert a file from another, it should
10645 call <prgn>dpkg-divert</prgn> in its preinst to add the
10646 diversion and rename the existing file. For example,
10647 supposing that a <prgn>smailwrapper</prgn> package wishes to
10648 install a wrapper around <file>/usr/sbin/smail</file>:
10650 dpkg-divert --package smailwrapper --add --rename \
10651 --divert /usr/sbin/smail.real /usr/sbin/smail
10652 </example> The <tt>--package smailwrapper</tt> ensures that
10653 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
10654 can bypass the diversion and get installed as the true version.
10655 It's safe to add the diversion unconditionally on upgrades since
10656 it will be left unchanged if it already exists, but
10657 <prgn>dpkg-divert</prgn> will display a message. To suppress that
10658 message, make the command conditional on the version from which
10659 the package is being upgraded:
10661 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
10662 dpkg-divert --package smailwrapper --add --rename \
10663 --divert /usr/sbin/smail.real /usr/sbin/smail
10665 </example> where <tt>1.0-2</tt> is the version at which the
10666 diversion was first added to the package. Running the command
10667 during abort-upgrade is pointless but harmless.
10671 The postrm has to do the reverse:
10673 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
10674 dpkg-divert --package smailwrapper --remove --rename \
10675 --divert /usr/sbin/smail.real /usr/sbin/smail
10677 </example> If the diversion was added at a particular version, the
10678 postrm should also handle the failure case of upgrading from an
10679 older version (unless the older version is so old that direct
10680 upgrades are no longer supported):
10682 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
10683 dpkg-divert --package smailwrapper --remove --rename \
10684 --divert /usr/sbin/smail.real /usr/sbin/smail
10686 </example> where <tt>1.02-2</tt> is the version at which the
10687 diversion was first added to the package. The postrm should not
10688 remove the diversion on upgrades both because there's no reason to
10689 remove the diversion only to immediately re-add it and since the
10690 postrm of the old package is run after unpacking so the removal of
10691 the diversion will fail.
10695 Do not attempt to divert a file which is vitally important for
10696 the system's operation - when using <prgn>dpkg-divert</prgn>
10697 there is a time, after it has been diverted but before
10698 <prgn>dpkg</prgn> has installed the new version, when the file
10699 does not exist.</p>
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