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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 interface not changing, and the package management
94 software authors need to ensure compatibility with
95 this interface definition. (Control file and
96 changelog file formats are examples.)
98 <tag>Chosen Convention</tag>
100 If there are a number of technically viable choices
101 that can be made, but one needs to select one of
102 these options for inter-operability. The version
103 number format is one example.
106 Please note that these are not mutually exclusive;
107 selected conventions often become parts of standard
113 The footnotes present in this manual are
114 merely informative, and are not part of Debian policy itself.
118 The appendices to this manual are not necessarily normative,
119 either. Please see <ref id="pkg-scope"> for more information.
123 In the normative part of this manual,
124 the words <em>must</em>, <em>should</em> and
125 <em>may</em>, and the adjectives <em>required</em>,
126 <em>recommended</em> and <em>optional</em>, are used to
127 distinguish the significance of the various guidelines in
128 this policy document. Packages that do not conform to the
129 guidelines denoted by <em>must</em> (or <em>required</em>)
130 will generally not be considered acceptable for the Debian
131 distribution. Non-conformance with guidelines denoted by
132 <em>should</em> (or <em>recommended</em>) will generally be
133 considered a bug, but will not necessarily render a package
134 unsuitable for distribution. Guidelines denoted by
135 <em>may</em> (or <em>optional</em>) are truly optional and
136 adherence is left to the maintainer's discretion.
140 These classifications are roughly equivalent to the bug
141 severities <em>serious</em> (for <em>must</em> or
142 <em>required</em> directive violations), <em>minor</em>,
143 <em>normal</em> or <em>important</em>
144 (for <em>should</em> or <em>recommended</em> directive
145 violations) and <em>wishlist</em> (for <em>optional</em>
148 Compare RFC 2119. Note, however, that these words are
149 used in a different way in this document.
154 Much of the information presented in this manual will be
155 useful even when building a package which is to be
156 distributed in some other way or is intended for local use
162 <heading>New versions of this document</heading>
165 This manual is distributed via the Debian package
166 <package><url name="debian-policy"
167 id="http://packages.debian.org/debian-policy"></package>
168 (<httpsite>packages.debian.org</httpsite>
169 <httppath>/debian-policy</httppath>).
173 The current version of this document is also available from
174 the Debian web mirrors at
175 <tt><url name="/doc/debian-policy/"
176 id="http://www.debian.org/doc/debian-policy/"></tt>.
178 <httpsite>www.debian.org</httpsite>
179 <httppath>/doc/debian-policy/</httppath>)
180 Also available from the same directory are several other
181 formats: <file>policy.html.tar.gz</file>
182 (<httppath>/doc/debian-policy/policy.html.tar.gz</httppath>),
183 <file>policy.pdf.gz</file>
184 (<httppath>/doc/debian-policy/policy.pdf.gz</httppath>)
185 and <file>policy.ps.gz</file>
186 (<httppath>/doc/debian-policy/policy.ps.gz</httppath>).
190 The <package>debian-policy</package> package also includes the file
191 <file>upgrading-checklist.txt.gz</file> which indicates policy
192 changes between versions of this document.
197 <heading>Authors and Maintainers</heading>
200 Originally called "Debian GNU/Linux Policy Manual", this
201 manual was initially written in 1996 by Ian Jackson.
202 It was revised on November 27th, 1996 by David A. Morris.
203 Christian Schwarz added new sections on March 15th, 1997,
204 and reworked/restructured it in April-July 1997.
205 Christoph Lameter contributed the "Web Standard".
206 Julian Gilbey largely restructured it in 2001.
210 Since September 1998, the responsibility for the contents of
211 this document lies on the <url name="debian-policy mailing list"
212 id="mailto:debian-policy@lists.debian.org">. Proposals
213 are discussed there and inserted into policy after a certain
214 consensus is established.
215 <!-- insert shameless policy-process plug here eventually -->
216 The actual editing is done by a group of maintainers that have
217 no editorial powers. These are the current maintainers:
220 <item>Julian Gilbey</item>
221 <item>Branden Robinson</item>
222 <item>Josip Rodin</item>
223 <item>Manoj Srivastava</item>
228 While the authors of this document have tried hard to avoid
229 typos and other errors, these do still occur. If you discover
230 an error in this manual or if you want to give any
231 comments, suggestions, or criticisms please send an email to
232 the Debian Policy List,
233 <email>debian-policy@lists.debian.org</email>, or submit a
234 bug report against the <tt>debian-policy</tt> package.
238 Please do not try to reach the individual authors or maintainers
239 of the Policy Manual regarding changes to the Policy.
244 <heading>Related documents</heading>
247 There are several other documents other than this Policy Manual
248 that are necessary to fully understand some Debian policies and
253 The external "sub-policy" documents are referred to in:
254 <list compact="compact">
255 <item><ref id="fhs"></item>
256 <item><ref id="virtual_pkg"></item>
257 <item><ref id="menus"></item>
258 <item><ref id="mime"></item>
259 <item><ref id="perl"></item>
260 <item><ref id="maintscriptprompt"></item>
261 <item><ref id="emacs"></item>
266 In addition to those, which carry the weight of policy, there
267 is the Debian Developer's Reference. This document describes
268 procedures and resources for Debian developers, but it is
269 <em>not</em> normative; rather, it includes things that don't
270 belong in the Policy, such as best practices for developers.
274 The Developer's Reference is available in the
275 <package>developers-reference</package> package.
276 It's also available from the Debian web mirrors at
277 <tt><url name="/doc/developers-reference/"
278 id="http://www.debian.org/doc/developers-reference/"></tt>.
282 <sect id="definitions">
283 <heading>Definitions</heading>
286 The following terms are used in this Policy Manual:
290 The character encoding specified by ANSI X3.4-1986 and its
291 predecessor standards, referred to in MIME as US-ASCII, and
292 corresponding to an encoding in eight bits per character of
293 the first 128 <url id="http://www.unicode.org/"
294 name="Unicode"> characters, with the eighth bit always zero.
298 The transformation format (sometimes called encoding) of
299 <url id="http://www.unicode.org/" name="Unicode"> defined by
300 <url id="http://www.rfc-editor.org/rfc/rfc3629.txt"
301 name="RFC 3629">. UTF-8 has the useful property of having
302 ASCII as a subset, so any text encoded in ASCII is trivially
312 <heading>The Debian Archive</heading>
315 The Debian GNU/Linux system is maintained and distributed as a
316 collection of <em>packages</em>. Since there are so many of
317 them (currently well over 15000), they are split into
318 <em>sections</em> and given <em>priorities</em> to simplify
319 the handling of them.
323 The effort of the Debian project is to build a free operating
324 system, but not every package we want to make accessible is
325 <em>free</em> in our sense (see the Debian Free Software
326 Guidelines, below), or may be imported/exported without
327 restrictions. Thus, the archive is split into areas<footnote>
328 The Debian archive software uses the term "component" internally
329 and in the Release file format to refer to the division of an
330 archive. The Debian Social Contract simply refers to "areas."
331 This document uses terminology similar to the Social Contract.
332 </footnote> based on their licenses and other restrictions.
336 The aims of this are:
338 <list compact="compact">
339 <item>to allow us to make as much software available as we can</item>
340 <item>to allow us to encourage everyone to write free software,
342 <item>to allow us to make it easy for people to produce
343 CD-ROMs of our system without violating any licenses,
344 import/export restrictions, or any other laws.</item>
349 The <em>main</em> archive area forms the <em>Debian GNU/Linux
354 Packages in the other archive areas (<tt>contrib</tt>,
355 <tt>non-free</tt>) are not considered to be part of the Debian
356 distribution, although we support their use and provide
357 infrastructure for them (such as our bug-tracking system and
358 mailing lists). This Debian Policy Manual applies to these
363 <heading>The Debian Free Software Guidelines</heading>
365 The Debian Free Software Guidelines (DFSG) form our
366 definition of "free software". These are:
368 <tag>1. Free Redistribution
371 The license of a Debian component may not restrict any
372 party from selling or giving away the software as a
373 component of an aggregate software distribution
374 containing programs from several different
375 sources. The license may not require a royalty or
376 other fee for such sale.
381 The program must include source code, and must allow
382 distribution in source code as well as compiled form.
384 <tag>3. Derived Works
387 The license must allow modifications and derived
388 works, and must allow them to be distributed under the
389 same terms as the license of the original software.
391 <tag>4. Integrity of The Author's Source Code
394 The license may restrict source-code from being
395 distributed in modified form <em>only</em> if the
396 license allows the distribution of "patch files"
397 with the source code for the purpose of modifying the
398 program at build time. The license must explicitly
399 permit distribution of software built from modified
400 source code. The license may require derived works to
401 carry a different name or version number from the
402 original software. (This is a compromise. The Debian
403 Project encourages all authors to not restrict any
404 files, source or binary, from being modified.)
406 <tag>5. No Discrimination Against Persons or Groups
409 The license must not discriminate against any person
412 <tag>6. No Discrimination Against Fields of Endeavor
415 The license must not restrict anyone from making use
416 of the program in a specific field of endeavor. For
417 example, it may not restrict the program from being
418 used in a business, or from being used for genetic
421 <tag>7. Distribution of License
424 The rights attached to the program must apply to all
425 to whom the program is redistributed without the need
426 for execution of an additional license by those
429 <tag>8. License Must Not Be Specific to Debian
432 The rights attached to the program must not depend on
433 the program's being part of a Debian system. If the
434 program is extracted from Debian and used or
435 distributed without Debian but otherwise within the
436 terms of the program's license, all parties to whom
437 the program is redistributed must have the same
438 rights as those that are granted in conjunction with
441 <tag>9. License Must Not Contaminate Other Software
444 The license must not place restrictions on other
445 software that is distributed along with the licensed
446 software. For example, the license must not insist
447 that all other programs distributed on the same medium
448 must be free software.
450 <tag>10. Example Licenses
453 The "GPL," "BSD," and "Artistic" licenses are examples of
454 licenses that we consider <em>free</em>.
461 <heading>Archive areas</heading>
464 <heading>The main archive area</heading>
467 Every package in <em>main</em> must comply with the DFSG
468 (Debian Free Software Guidelines).
472 In addition, the packages in <em>main</em>
473 <list compact="compact">
475 must not require a package outside of <em>main</em>
476 for compilation or execution (thus, the package must
477 not declare a "Depends", "Recommends", or
478 "Build-Depends" relationship on a non-<em>main</em>
482 must not be so buggy that we refuse to support them,
486 must meet all policy requirements presented in this
495 <heading>The contrib archive area</heading>
498 Every package in <em>contrib</em> must comply with the DFSG.
502 In addition, the packages in <em>contrib</em>
503 <list compact="compact">
505 must not be so buggy that we refuse to support them,
509 must meet all policy requirements presented in this
517 Examples of packages which would be included in
518 <em>contrib</em> are:
519 <list compact="compact">
521 free packages which require <em>contrib</em>,
522 <em>non-free</em> packages or packages which are not
523 in our archive at all for compilation or execution,
527 wrapper packages or other sorts of free accessories for
534 <sect1 id="non-free">
535 <heading>The non-free archive area</heading>
538 Packages must be placed in <em>non-free</em> if they are
539 not compliant with the DFSG or are encumbered by patents
540 or other legal issues that make their distribution
545 In addition, the packages in <em>non-free</em>
546 <list compact="compact">
548 must not be so buggy that we refuse to support them,
552 must meet all policy requirements presented in this
553 manual that it is possible for them to meet.
555 It is possible that there are policy
556 requirements which the package is unable to
557 meet, for example, if the source is
558 unavailable. These situations will need to be
559 handled on a case-by-case basis.
568 <sect id="pkgcopyright">
569 <heading>Copyright considerations</heading>
572 Every package must be accompanied by a verbatim copy of its
573 copyright information and distribution license in the file
574 <file>/usr/share/doc/<var>package</var>/copyright</file>
575 (see <ref id="copyrightfile"> for further details).
579 We reserve the right to restrict files from being included
580 anywhere in our archives if
581 <list compact="compact">
583 their use or distribution would break a law,
586 there is an ethical conflict in their distribution or
590 we would have to sign a license for them, or
593 their distribution would conflict with other project
600 Programs whose authors encourage the user to make
601 donations are fine for the main distribution, provided
602 that the authors do not claim that not donating is
603 immoral, unethical, illegal or something similar; in such
604 a case they must go in <em>non-free</em>.
608 Packages whose copyright permission notices (or patent
609 problems) do not even allow redistribution of binaries
610 only, and where no special permission has been obtained,
611 must not be placed on the Debian FTP site and its mirrors
616 Note that under international copyright law (this applies
617 in the United States, too), <em>no</em> distribution or
618 modification of a work is allowed without an explicit
619 notice saying so. Therefore a program without a copyright
620 notice <em>is</em> copyrighted and you may not do anything
621 to it without risking being sued! Likewise if a program
622 has a copyright notice but no statement saying what is
623 permitted then nothing is permitted.
627 Many authors are unaware of the problems that restrictive
628 copyrights (or lack of copyright notices) can cause for
629 the users of their supposedly-free software. It is often
630 worthwhile contacting such authors diplomatically to ask
631 them to modify their license terms. However, this can be a
632 politically difficult thing to do and you should ask for
633 advice on the <tt>debian-legal</tt> mailing list first, as
638 When in doubt about a copyright, send mail to
639 <email>debian-legal@lists.debian.org</email>. Be prepared
640 to provide us with the copyright statement. Software
641 covered by the GPL, public domain software and BSD-like
642 copyrights are safe; be wary of the phrases "commercial
643 use prohibited" and "distribution restricted".
647 <sect id="subsections">
648 <heading>Sections</heading>
651 The packages in the archive areas <em>main</em>,
652 <em>contrib</em> and <em>non-free</em> are grouped further into
653 <em>sections</em> to simplify handling.
657 The archive area and section for each package should be
658 specified in the package's <tt>Section</tt> control record (see
659 <ref id="f-Section">). However, the maintainer of the Debian
660 archive may override this selection to ensure the consistency of
661 the Debian distribution. The <tt>Section</tt> field should be
663 <list compact="compact">
665 <em>section</em> if the package is in the
666 <em>main</em> archive area,
669 <em>area/section</em> if the package is in
670 the <em>contrib</em> or <em>non-free</em>
677 The Debian archive maintainers provide the authoritative
678 list of sections. At present, they are:
679 <em>admin</em>, <em>cli-mono</em>, <em>comm</em>, <em>database</em>,
680 <em>devel</em>, <em>debug</em>, <em>doc</em>, <em>editors</em>,
681 <em>electronics</em>, <em>embedded</em>, <em>fonts</em>,
682 <em>games</em>, <em>gnome</em>, <em>graphics</em>, <em>gnu-r</em>,
683 <em>gnustep</em>, <em>hamradio</em>, <em>haskell</em>,
684 <em>httpd</em>, <em>interpreters</em>, <em>java</em>, <em>kde</em>,
685 <em>kernel</em>, <em>libs</em>, <em>libdevel</em>, <em>lisp</em>,
686 <em>localization</em>, <em>mail</em>, <em>math</em>, <em>misc</em>,
687 <em>net</em>, <em>news</em>, <em>ocaml</em>, <em>oldlibs</em>,
688 <em>otherosfs</em>, <em>perl</em>, <em>php</em>, <em>python</em>,
689 <em>ruby</em>, <em>science</em>, <em>shells</em>, <em>sound</em>,
690 <em>tex</em>, <em>text</em>, <em>utils</em>, <em>vcs</em>,
691 <em>video</em>, <em>web</em>, <em>x11</em>, <em>xfce</em>,
692 <em>zope</em>. The additional section <em>debian-installer</em>
693 contains special packages used by the installer and is not used
694 for normal Debian packages.
698 For more information about the sections and their definitions,
699 see the <url id="http://packages.debian.org/unstable/"
700 name="list of sections in unstable">.
704 <sect id="priorities">
705 <heading>Priorities</heading>
708 Each package should have a <em>priority</em> value, which is
709 included in the package's <em>control record</em>
710 (see <ref id="f-Priority">).
711 This information is used by the Debian package management tools to
712 separate high-priority packages from less-important packages.
716 The following <em>priority levels</em> are recognized by the
717 Debian package management tools.
719 <tag><tt>required</tt></tag>
721 Packages which are necessary for the proper
722 functioning of the system (usually, this means that
723 dpkg functionality depends on these packages).
724 Removing a <tt>required</tt> package may cause your
725 system to become totally broken and you may not even
726 be able to use <prgn>dpkg</prgn> to put things back,
727 so only do so if you know what you are doing. Systems
728 with only the <tt>required</tt> packages are probably
729 unusable, but they do have enough functionality to
730 allow the sysadmin to boot and install more software.
732 <tag><tt>important</tt></tag>
734 Important programs, including those which one would
735 expect to find on any Unix-like system. If the
736 expectation is that an experienced Unix person who
737 found it missing would say "What on earth is going on,
738 where is <prgn>foo</prgn>?", it must be an
739 <tt>important</tt> package.<footnote>
740 This is an important criterion because we are
741 trying to produce, amongst other things, a free
744 Other packages without which the system will not run
745 well or be usable must also have priority
746 <tt>important</tt>. This does
747 <em>not</em> include Emacs, the X Window System, TeX
748 or any other large applications. The
749 <tt>important</tt> packages are just a bare minimum of
750 commonly-expected and necessary tools.
752 <tag><tt>standard</tt></tag>
754 These packages provide a reasonably small but not too
755 limited character-mode system. This is what will be
756 installed by default if the user doesn't select anything
757 else. It doesn't include many large applications.
759 <tag><tt>optional</tt></tag>
761 (In a sense everything that isn't required is
762 optional, but that's not what is meant here.) This is
763 all the software that you might reasonably want to
764 install if you didn't know what it was and don't have
765 specialized requirements. This is a much larger system
766 and includes the X Window System, a full TeX
767 distribution, and many applications. Note that
768 optional packages should not conflict with each other.
770 <tag><tt>extra</tt></tag>
772 This contains all packages that conflict with others
773 with required, important, standard or optional
774 priorities, or are only likely to be useful if you
775 already know what they are or have specialized
776 requirements (such as packages containing only detached
783 Packages must not depend on packages with lower priority
784 values (excluding build-time dependencies). In order to
785 ensure this, the priorities of one or more packages may need
794 <heading>Binary packages</heading>
797 The Debian GNU/Linux distribution is based on the Debian
798 package management system, called <prgn>dpkg</prgn>. Thus,
799 all packages in the Debian distribution must be provided
800 in the <tt>.deb</tt> file format.
804 <heading>The package name</heading>
807 Every package must have a name that's unique within the Debian
812 The package name is included in the control field
813 <tt>Package</tt>, the format of which is described
814 in <ref id="f-Package">.
815 The package name is also included as a part of the file name
816 of the <tt>.deb</tt> file.
821 <heading>The version of a package</heading>
824 Every package has a version number recorded in its
825 <tt>Version</tt> control file field, described in
826 <ref id="f-Version">.
830 The package management system imposes an ordering on version
831 numbers, so that it can tell whether packages are being up- or
832 downgraded and so that package system front end applications
833 can tell whether a package it finds available is newer than
834 the one installed on the system. The version number format
835 has the most significant parts (as far as comparison is
836 concerned) at the beginning.
840 If an upstream package has problematic version numbers they
841 should be converted to a sane form for use in the
842 <tt>Version</tt> field.
846 <heading>Version numbers based on dates</heading>
849 In general, Debian packages should use the same version
850 numbers as the upstream sources.
854 However, in some cases where the upstream version number is
855 based on a date (e.g., a development "snapshot" release) the
856 package management system cannot handle these version
857 numbers without epochs. For example, dpkg will consider
858 "96May01" to be greater than "96Dec24".
862 To prevent having to use epochs for every new upstream
863 version, the date based portion of the version number
864 should be changed to the following format in such cases:
865 "19960501", "19961224". It is up to the maintainer whether
866 they want to bother the upstream maintainer to change
867 the version numbers upstream, too.
871 Note that other version formats based on dates which are
872 parsed correctly by the package management system should
873 <em>not</em> be changed.
877 Native Debian packages (i.e., packages which have been
878 written especially for Debian) whose version numbers include
879 dates should always use the "YYYYMMDD" format.
886 <heading>The maintainer of a package</heading>
889 Every package must have a Debian maintainer (the
890 maintainer may be one person or a group of people
891 reachable from a common email address, such as a mailing
892 list). The maintainer is responsible for ensuring that
893 the package is placed in the appropriate distributions.
897 The maintainer must be specified in the
898 <tt>Maintainer</tt> control field with their correct name
899 and a working email address. If one person maintains
900 several packages, they should try to avoid having
901 different forms of their name and email address in
902 the <tt>Maintainer</tt> fields of those packages.
906 The format of the <tt>Maintainer</tt> control field is
907 described in <ref id="f-Maintainer">.
911 If the maintainer of a package quits from the Debian
912 project, "Debian QA Group"
913 <email>packages@qa.debian.org</email> takes over the
914 maintainer-ship of the package until someone else
915 volunteers for that task. These packages are called
916 <em>orphaned packages</em>.<footnote>
917 The detailed procedure for doing this gracefully can
918 be found in the Debian Developer's Reference,
919 see <ref id="related">.
924 <sect id="descriptions">
925 <heading>The description of a package</heading>
928 Every Debian package must have an extended description
929 stored in the appropriate field of the control record.
930 The technical information about the format of the
931 <tt>Description</tt> field is in <ref id="f-Description">.
935 The description should describe the package (the program) to a
936 user (system administrator) who has never met it before so that
937 they have enough information to decide whether they want to
938 install it. This description should not just be copied verbatim
939 from the program's documentation.
943 Put important information first, both in the synopsis and
944 extended description. Sometimes only the first part of the
945 synopsis or of the description will be displayed. You can
946 assume that there will usually be a way to see the whole
947 extended description.
951 The description should also give information about the
952 significant dependencies and conflicts between this package
953 and others, so that the user knows why these dependencies and
954 conflicts have been declared.
958 Instructions for configuring or using the package should
959 not be included (that is what installation scripts,
960 manual pages, info files, etc., are for). Copyright
961 statements and other administrivia should not be included
962 either (that is what the copyright file is for).
965 <sect1 id="synopsis"><heading>The single line synopsis</heading>
968 The single line synopsis should be kept brief - certainly
973 Do not include the package name in the synopsis line. The
974 display software knows how to display this already, and you
975 do not need to state it. Remember that in many situations
976 the user may only see the synopsis line - make it as
977 informative as you can.
982 <sect1 id="extendeddesc"><heading>The extended description</heading>
985 Do not try to continue the single line synopsis into the
986 extended description. This will not work correctly when
987 the full description is displayed, and makes no sense
988 where only the summary (the single line synopsis) is
993 The extended description should describe what the package
994 does and how it relates to the rest of the system (in terms
995 of, for example, which subsystem it is which part of).
999 The description field needs to make sense to anyone, even
1000 people who have no idea about any of the things the
1001 package deals with.<footnote>
1002 The blurb that comes with a program in its
1003 announcements and/or <prgn>README</prgn> files is
1004 rarely suitable for use in a description. It is
1005 usually aimed at people who are already in the
1006 community where the package is used.
1015 <heading>Dependencies</heading>
1018 Every package must specify the dependency information
1019 about other packages that are required for the first to
1024 For example, a dependency entry must be provided for any
1025 shared libraries required by a dynamically-linked executable
1026 binary in a package.
1030 Packages are not required to declare any dependencies they
1031 have on other packages which are marked <tt>Essential</tt>
1032 (see below), and should not do so unless they depend on a
1033 particular version of that package.<footnote>
1035 Essential is needed in part to avoid unresolvable dependency
1036 loops on upgrade. If packages add unnecessary dependencies
1037 on packages in this set, the chances that there
1038 <strong>will</strong> be an unresolvable dependency loop
1039 caused by forcing these Essential packages to be configured
1040 first before they need to be is greatly increased. It also
1041 increases the chances that frontends will be unable to
1042 <strong>calculate</strong> an upgrade path, even if one
1046 Also, functionality is rarely ever removed from the
1047 Essential set, but <em>packages</em> have been removed from
1048 the Essential set when the functionality moved to a
1049 different package. So depending on these packages <em>just
1050 in case</em> they stop being essential does way more harm
1057 Sometimes, a package requires another package to be installed
1058 <em>and</em> configured before it can be installed. In this
1059 case, you must specify a <tt>Pre-Depends</tt> entry for
1064 You should not specify a <tt>Pre-Depends</tt> entry for a
1065 package before this has been discussed on the
1066 <tt>debian-devel</tt> mailing list and a consensus about
1067 doing that has been reached.
1071 The format of the package interrelationship control fields is
1072 described in <ref id="relationships">.
1076 <sect id="virtual_pkg">
1077 <heading>Virtual packages</heading>
1080 Sometimes, there are several packages which offer
1081 more-or-less the same functionality. In this case, it's
1082 useful to define a <em>virtual package</em> whose name
1083 describes that common functionality. (The virtual
1084 packages only exist logically, not physically; that's why
1085 they are called <em>virtual</em>.) The packages with this
1086 particular function will then <em>provide</em> the virtual
1087 package. Thus, any other package requiring that function
1088 can simply depend on the virtual package without having to
1089 specify all possible packages individually.
1093 All packages should use virtual package names where
1094 appropriate, and arrange to create new ones if necessary.
1095 They should not use virtual package names (except privately,
1096 amongst a cooperating group of packages) unless they have
1097 been agreed upon and appear in the list of virtual package
1098 names. (See also <ref id="virtual">)
1102 The latest version of the authoritative list of virtual
1103 package names can be found in the <tt>debian-policy</tt> package.
1104 It is also available from the Debian web mirrors at
1105 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1106 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>.
1110 The procedure for updating the list is described in the preface
1117 <heading>Base system</heading>
1120 The <tt>base system</tt> is a minimum subset of the Debian
1121 GNU/Linux system that is installed before everything else
1122 on a new system. Only very few packages are allowed to form
1123 part of the base system, in order to keep the required disk
1128 The base system consists of all those packages with priority
1129 <tt>required</tt> or <tt>important</tt>. Many of them will
1130 be tagged <tt>essential</tt> (see below).
1135 <heading>Essential packages</heading>
1138 Essential is defined as the minimal set of functionality that
1139 must be available and usable on the system at all times, even
1140 when packages are in an unconfigured (but unpacked) state.
1141 Packages are tagged <tt>essential</tt> for a system using the
1142 <tt>Essential</tt> control file field. The format of the
1143 <tt>Essential</tt> control field is described in <ref
1148 Since these packages cannot be easily removed (one has to
1149 specify an extra <em>force option</em> to
1150 <prgn>dpkg</prgn> to do so), this flag must not be used
1151 unless absolutely necessary. A shared library package
1152 must not be tagged <tt>essential</tt>; dependencies will
1153 prevent its premature removal, and we need to be able to
1154 remove it when it has been superseded.
1158 Since dpkg will not prevent upgrading of other packages
1159 while an <tt>essential</tt> package is in an unconfigured
1160 state, all <tt>essential</tt> packages must supply all of
1161 their core functionality even when unconfigured. If the
1162 package cannot satisfy this requirement it must not be
1163 tagged as essential, and any packages depending on this
1164 package must instead have explicit dependency fields as
1169 Maintainers should take great care in adding any programs,
1170 interfaces, or functionality to <tt>essential</tt> packages.
1171 Packages may assume that functionality provided by
1172 <tt>essential</tt> packages is always available without
1173 declaring explicit dependencies, which means that removing
1174 functionality from the Essential set is very difficult and is
1175 almost never done. Any capability added to an
1176 <tt>essential</tt> package therefore creates an obligation to
1177 support that capability as part of the Essential set in
1182 You must not tag any packages <tt>essential</tt> before
1183 this has been discussed on the <tt>debian-devel</tt>
1184 mailing list and a consensus about doing that has been
1189 <sect id="maintscripts">
1190 <heading>Maintainer Scripts</heading>
1193 The package installation scripts should avoid producing
1194 output which is unnecessary for the user to see and
1195 should rely on <prgn>dpkg</prgn> to stave off boredom on
1196 the part of a user installing many packages. This means,
1197 amongst other things, using the <tt>--quiet</tt> option on
1198 <prgn>install-info</prgn>.
1202 Errors which occur during the execution of an installation
1203 script must be checked and the installation must not
1204 continue after an error.
1208 Note that in general <ref id="scripts"> applies to package
1209 maintainer scripts, too.
1213 You should not use <prgn>dpkg-divert</prgn> on a file
1214 belonging to another package without consulting the
1215 maintainer of that package first.
1219 All packages which supply an instance of a common command
1220 name (or, in general, filename) should generally use
1221 <prgn>update-alternatives</prgn>, so that they may be
1222 installed together. If <prgn>update-alternatives</prgn>
1223 is not used, then each package must use
1224 <tt>Conflicts</tt> to ensure that other packages are
1225 de-installed. (In this case, it may be appropriate to
1226 specify a conflict against earlier versions of something
1227 that previously did not use
1228 <prgn>update-alternatives</prgn>; this is an exception to
1229 the usual rule that versioned conflicts should be
1233 <sect1 id="maintscriptprompt">
1234 <heading>Prompting in maintainer scripts</heading>
1236 Package maintainer scripts may prompt the user if
1237 necessary. Prompting must be done by communicating
1238 through a program, such as <prgn>debconf</prgn>, which
1239 conforms to the Debian Configuration Management
1240 Specification, version 2 or higher.
1244 Packages which are essential, or which are dependencies of
1245 essential packages, may fall back on another prompting method
1246 if no such interface is available when they are executed.
1250 The Debian Configuration Management Specification is included
1251 in the <file>debconf_specification</file> files in the
1252 <package>debian-policy</package> package.
1253 It is also available from the Debian web mirrors at
1254 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1255 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>.
1259 Packages which use the Debian Configuration Management
1260 Specification may contain an additional
1261 <prgn>config</prgn> script and a <tt>templates</tt>
1262 file in their control archive<footnote>
1263 The control.tar.gz inside the .deb.
1264 See <manref name="deb" section="5">.
1266 The <prgn>config</prgn> script might be run before the
1267 <prgn>preinst</prgn> script, and before the package is unpacked
1268 or any of its dependencies or pre-dependencies are satisfied.
1269 Therefore it must work using only the tools present in
1270 <em>essential</em> packages.<footnote>
1271 <package>Debconf</package> or another tool that
1272 implements the Debian Configuration Management
1273 Specification will also be installed, and any
1274 versioned dependencies on it will be satisfied
1275 before preconfiguration begins.
1280 Packages which use the Debian Configuration Management
1281 Specification must allow for translation of their user-visible
1282 messages by using a gettext-based system such as the one
1283 provided by the <package>po-debconf</package> package.
1287 Packages should try to minimize the amount of prompting
1288 they need to do, and they should ensure that the user
1289 will only ever be asked each question once. This means
1290 that packages should try to use appropriate shared
1291 configuration files (such as <file>/etc/papersize</file> and
1292 <file>/etc/news/server</file>), and shared
1293 <package>debconf</package> variables rather than each
1294 prompting for their own list of required pieces of
1299 It also means that an upgrade should not ask the same
1300 questions again, unless the user has used
1301 <tt>dpkg --purge</tt> to remove the package's configuration.
1302 The answers to configuration questions should be stored in an
1303 appropriate place in <file>/etc</file> so that the user can
1304 modify them, and how this has been done should be
1309 If a package has a vitally important piece of
1310 information to pass to the user (such as "don't run me
1311 as I am, you must edit the following configuration files
1312 first or you risk your system emitting badly-formatted
1313 messages"), it should display this in the
1314 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1315 prompt the user to hit return to acknowledge the
1316 message. Copyright messages do not count as vitally
1317 important (they belong in
1318 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1319 neither do instructions on how to use a program (these
1320 should be in on-line documentation, where all the users
1325 Any necessary prompting should almost always be confined
1326 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1327 script. If it is done in the <prgn>postinst</prgn>, it
1328 should be protected with a conditional so that
1329 unnecessary prompting doesn't happen if a package's
1330 installation fails and the <prgn>postinst</prgn> is
1331 called with <tt>abort-upgrade</tt>,
1332 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1342 <heading>Source packages</heading>
1344 <sect id="standardsversion">
1345 <heading>Standards conformance</heading>
1348 Source packages should specify the most recent version number
1349 of this policy document with which your package complied
1350 when it was last updated.
1354 This information may be used to file bug reports
1355 automatically if your package becomes too much out of date.
1359 The version is specified in the <tt>Standards-Version</tt>
1361 The format of the <tt>Standards-Version</tt> field is
1362 described in <ref id="f-Standards-Version">.
1366 You should regularly, and especially if your package has
1367 become out of date, check for the newest Policy Manual
1368 available and update your package, if necessary. When your
1369 package complies with the new standards you should update the
1370 <tt>Standards-Version</tt> source package field and
1371 release it.<footnote>
1372 See the file <file>upgrading-checklist</file> for
1373 information about policy which has changed between
1374 different versions of this document.
1380 <sect id="pkg-relations">
1381 <heading>Package relationships</heading>
1384 Source packages should specify which binary packages they
1385 require to be installed or not to be installed in order to
1386 build correctly. For example, if building a package
1387 requires a certain compiler, then the compiler should be
1388 specified as a build-time dependency.
1392 It is not necessary to explicitly specify build-time
1393 relationships on a minimal set of packages that are always
1394 needed to compile, link and put in a Debian package a
1395 standard "Hello World!" program written in C or C++. The
1396 required packages are called <em>build-essential</em>, and
1397 an informational list can be found in
1398 <file>/usr/share/doc/build-essential/list</file> (which is
1399 contained in the <tt>build-essential</tt>
1402 <list compact="compact">
1404 This allows maintaining the list separately
1405 from the policy documents (the list does not
1406 need the kind of control that the policy
1410 Having a separate package allows one to install
1411 the build-essential packages on a machine, as
1412 well as allowing other packages such as tasks to
1413 require installation of the build-essential
1414 packages using the depends relation.
1417 The separate package allows bug reports against
1418 the list to be categorized separately from
1419 the policy management process in the BTS.
1426 When specifying the set of build-time dependencies, one
1427 should list only those packages explicitly required by the
1428 build. It is not necessary to list packages which are
1429 required merely because some other package in the list of
1430 build-time dependencies depends on them.<footnote>
1431 The reason for this is that dependencies change, and
1432 you should list all those packages, and <em>only</em>
1433 those packages that <em>you</em> need directly. What
1434 others need is their business. For example, if you
1435 only link against <file>libimlib</file>, you will need to
1436 build-depend on <package>libimlib2-dev</package> but
1437 not against any <tt>libjpeg*</tt> packages, even
1438 though <tt>libimlib2-dev</tt> currently depends on
1439 them: installation of <package>libimlib2-dev</package>
1440 will automatically ensure that all of its run-time
1441 dependencies are satisfied.
1446 If build-time dependencies are specified, it must be
1447 possible to build the package and produce working binaries
1448 on a system with only essential and build-essential
1449 packages installed and also those required to satisfy the
1450 build-time relationships (including any implied
1451 relationships). In particular, this means that version
1452 clauses should be used rigorously in build-time
1453 relationships so that one cannot produce bad or
1454 inconsistently configured packages when the relationships
1455 are properly satisfied.
1459 <ref id="relationships"> explains the technical details.
1464 <heading>Changes to the upstream sources</heading>
1467 If changes to the source code are made that are not
1468 specific to the needs of the Debian system, they should be
1469 sent to the upstream authors in whatever form they prefer
1470 so as to be included in the upstream version of the
1475 If you need to configure the package differently for
1476 Debian or for Linux, and the upstream source doesn't
1477 provide a way to do so, you should add such configuration
1478 facilities (for example, a new <prgn>autoconf</prgn> test
1479 or <tt>#define</tt>) and send the patch to the upstream
1480 authors, with the default set to the way they originally
1481 had it. You can then easily override the default in your
1482 <file>debian/rules</file> or wherever is appropriate.
1486 You should make sure that the <prgn>configure</prgn> utility
1487 detects the correct architecture specification string
1488 (refer to <ref id="arch-spec"> for details).
1492 If you need to edit a <prgn>Makefile</prgn> where GNU-style
1493 <prgn>configure</prgn> scripts are used, you should edit the
1494 <file>.in</file> files rather than editing the
1495 <prgn>Makefile</prgn> directly. This allows the user to
1496 reconfigure the package if necessary. You should
1497 <em>not</em> configure the package and edit the generated
1498 <prgn>Makefile</prgn>! This makes it impossible for someone
1499 else to later reconfigure the package without losing the
1505 <sect id="dpkgchangelog">
1506 <heading>Debian changelog: <file>debian/changelog</file></heading>
1509 Changes in the Debian version of the package should be
1510 briefly explained in the Debian changelog file
1511 <file>debian/changelog</file>.<footnote>
1513 Mistakes in changelogs are usually best rectified by
1514 making a new changelog entry rather than "rewriting
1515 history" by editing old changelog entries.
1518 This includes modifications
1519 made in the Debian package compared to the upstream one
1520 as well as other changes and updates to the package.
1522 Although there is nothing stopping an author who is also
1523 the Debian maintainer from using this changelog for all
1524 their changes, it will have to be renamed if the Debian
1525 and upstream maintainers become different people. In such
1526 a case, however, it might be better to maintain the package
1527 as a non-native package.
1532 The format of the <file>debian/changelog</file> allows the
1533 package building tools to discover which version of the package
1534 is being built and find out other release-specific information.
1538 That format is a series of entries like this:
1540 <example compact="compact">
1541 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1543 [optional blank line(s), stripped]
1545 * <var>change details</var>
1546 <var>more change details</var>
1548 [blank line(s), included in output of dpkg-parsechangelog]
1550 * <var>even more change details</var>
1552 [optional blank line(s), stripped]
1554 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1559 <var>package</var> and <var>version</var> are the source
1560 package name and version number.
1564 <var>distribution(s)</var> lists the distributions where
1565 this version should be installed when it is uploaded - it
1566 is copied to the <tt>Distribution</tt> field in the
1567 <file>.changes</file> file. See <ref id="f-Distribution">.
1571 <var>urgency</var> is the value for the <tt>Urgency</tt>
1572 field in the <file>.changes</file> file for the upload
1573 (see <ref id="f-Urgency">). It is not possible to specify
1574 an urgency containing commas; commas are used to separate
1575 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1576 <prgn>dpkg</prgn> changelog format (though there is
1577 currently only one useful <var>keyword</var>,
1582 The change details may in fact be any series of lines
1583 starting with at least two spaces, but conventionally each
1584 change starts with an asterisk and a separating space and
1585 continuation lines are indented so as to bring them in
1586 line with the start of the text above. Blank lines may be
1587 used here to separate groups of changes, if desired.
1591 If this upload resolves bugs recorded in the Bug Tracking
1592 System (BTS), they may be automatically closed on the
1593 inclusion of this package into the Debian archive by
1594 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1595 in the change details.<footnote>
1596 To be precise, the string should match the following
1597 Perl regular expression:
1599 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1601 Then all of the bug numbers listed will be closed by the
1602 archive maintenance script (<prgn>katie</prgn>) using the
1603 <var>version</var> of the changelog entry.
1605 This information is conveyed via the <tt>Closes</tt> field
1606 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1610 The maintainer name and email address used in the changelog
1611 should be the details of the person uploading <em>this</em>
1612 version. They are <em>not</em> necessarily those of the
1613 usual package maintainer. The information here will be
1614 copied to the <tt>Changed-By</tt> field in the
1615 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1616 and then later used to send an acknowledgement when the
1617 upload has been installed.
1621 The <var>date</var> must be in RFC822 format<footnote>
1622 This is generated by <tt>date -R</tt>.
1623 </footnote>; it must include the time zone specified
1624 numerically, with the time zone name or abbreviation
1625 optionally present as a comment in parentheses.
1629 The first "title" line with the package name must start
1630 at the left hand margin. The "trailer" line with the
1631 maintainer and date details must be preceded by exactly
1632 one space. The maintainer details and the date must be
1633 separated by exactly two spaces.
1637 The entire changelog must be encoded in UTF-8.
1641 For more information on placement of the changelog files
1642 within binary packages, please see <ref id="changelogs">.
1646 <sect id="dpkgcopyright">
1647 <heading>Copyright: <file>debian/copyright</file></heading>
1649 Every package must be accompanied by a verbatim copy of its
1650 copyright information and distribution license in the file
1651 <file>/usr/share/doc/<var>package</var>/copyright</file>
1652 (see <ref id="copyrightfile"> for further details). Also see
1653 <ref id="pkgcopyright"> for further considerations related
1654 to copyrights for packages.
1658 <heading>Error trapping in makefiles</heading>
1661 When <prgn>make</prgn> invokes a command in a makefile
1662 (including your package's upstream makefiles and
1663 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1664 means that <prgn>sh</prgn>'s usual bad error handling
1665 properties apply: if you include a miniature script as one
1666 of the commands in your makefile you'll find that if you
1667 don't do anything about it then errors are not detected
1668 and <prgn>make</prgn> will blithely continue after
1673 Every time you put more than one shell command (this
1674 includes using a loop) in a makefile command you
1675 must make sure that errors are trapped. For
1676 simple compound commands, such as changing directory and
1677 then running a program, using <tt>&&</tt> rather
1678 than semicolon as a command separator is sufficient. For
1679 more complex commands including most loops and
1680 conditionals you should include a separate <tt>set -e</tt>
1681 command at the start of every makefile command that's
1682 actually one of these miniature shell scripts.
1686 <sect id="timestamps">
1687 <heading>Time Stamps</heading>
1689 Maintainers should preserve the modification times of the
1690 upstream source files in a package, as far as is reasonably
1692 The rationale is that there is some information conveyed
1693 by knowing the age of the file, for example, you could
1694 recognize that some documentation is very old by looking
1695 at the modification time, so it would be nice if the
1696 modification time of the upstream source would be
1702 <sect id="restrictions">
1703 <heading>Restrictions on objects in source packages</heading>
1706 The source package may not contain any hard links<footnote>
1708 This is not currently detected when building source
1709 packages, but only when extracting
1713 Hard links may be permitted at some point in the
1714 future, but would require a fair amount of
1717 </footnote>, device special files, sockets or setuid or
1718 setgid files.<footnote>
1719 Setgid directories are allowed.
1724 <sect id="debianrules">
1725 <heading>Main building script: <file>debian/rules</file></heading>
1728 This file must be an executable makefile, and contains the
1729 package-specific recipes for compiling the package and
1730 building binary package(s) from the source.
1734 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1735 so that it can be invoked by saying its name rather than
1736 invoking <prgn>make</prgn> explicitly. That is, invoking
1737 either of <tt>make -f debian/rules <em>args...</em></tt>
1738 or <tt>./debian/rules <em>args...</em></tt> must result in
1743 Since an interactive <file>debian/rules</file> script makes it
1744 impossible to auto-compile that package and also makes it
1745 hard for other people to reproduce the same binary
1746 package, all <em>required targets</em> must be
1747 non-interactive. At a minimum, required targets are the
1748 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1749 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1750 <em>binary-indep</em>, and <em>build</em>. It also follows
1751 that any target that these targets depend on must also be
1756 The targets are as follows (required unless stated otherwise):
1758 <tag><tt>build</tt></tag>
1761 The <tt>build</tt> target should perform all the
1762 configuration and compilation of the package.
1763 If a package has an interactive pre-build
1764 configuration routine, the Debianized source package
1765 must either be built after this has taken place (so
1766 that the binary package can be built without rerunning
1767 the configuration) or the configuration routine
1768 modified to become non-interactive. (The latter is
1769 preferable if there are architecture-specific features
1770 detected by the configuration routine.)
1774 For some packages, notably ones where the same
1775 source tree is compiled in different ways to produce
1776 two binary packages, the <tt>build</tt> target
1777 does not make much sense. For these packages it is
1778 good enough to provide two (or more) targets
1779 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1780 for each of the ways of building the package, and a
1781 <tt>build</tt> target that does nothing. The
1782 <tt>binary</tt> target will have to build the
1783 package in each of the possible ways and make the
1784 binary package out of each.
1788 The <tt>build</tt> target must not do anything
1789 that might require root privilege.
1793 The <tt>build</tt> target may need to run the
1794 <tt>clean</tt> target first - see below.
1798 When a package has a configuration and build routine
1799 which takes a long time, or when the makefiles are
1800 poorly designed, or when <tt>build</tt> needs to
1801 run <tt>clean</tt> first, it is a good idea to
1802 <tt>touch build</tt> when the build process is
1803 complete. This will ensure that if <tt>debian/rules
1804 build</tt> is run again it will not rebuild the whole
1806 Another common way to do this is for <tt>build</tt>
1807 to depend on <prgn>build-stamp</prgn> and to do
1808 nothing else, and for the <prgn>build-stamp</prgn>
1809 target to do the building and to <tt>touch
1810 build-stamp</tt> on completion. This is
1811 especially useful if the build routine creates a
1812 file or directory called <tt>build</tt>; in such a
1813 case, <tt>build</tt> will need to be listed as
1814 a phony target (i.e., as a dependency of the
1815 <tt>.PHONY</tt> target). See the documentation of
1816 <prgn>make</prgn> for more information on phony
1822 <tag><tt>build-arch</tt> (optional),
1823 <tt>build-indep</tt> (optional)
1827 A package may also provide both of the targets
1828 <tt>build-arch</tt> and <tt>build-indep</tt>.
1829 The <tt>build-arch</tt> target, if provided, should
1830 perform all the configuration and compilation required
1831 for producing all architecture-dependant binary packages
1832 (those packages for which the body of the
1833 <tt>Architecture</tt> field in <tt>debian/control</tt>
1834 is not <tt>all</tt>).
1835 Similarly, the <tt>build-indep</tt> target, if
1836 provided, should perform all the configuration and
1837 compilation required for producing all
1838 architecture-independent binary packages
1839 (those packages for which the body of the
1840 <tt>Architecture</tt> field in <tt>debian/control</tt>
1842 The <tt>build</tt> target should depend on those of the
1843 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1844 are provided in the rules file.
1848 If one or both of the targets <tt>build-arch</tt> and
1849 <tt>build-indep</tt> are not provided, then invoking
1850 <file>debian/rules</file> with one of the not-provided
1851 targets as arguments should produce a exit status code
1852 of 2. Usually this is provided automatically by make
1853 if the target is missing.
1857 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1858 must not do anything that might require root privilege.
1862 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1863 <tt>binary-indep</tt>
1867 The <tt>binary</tt> target must be all that is
1868 necessary for the user to build the binary package(s)
1869 produced from this source package. It is
1870 split into two parts: <prgn>binary-arch</prgn> builds
1871 the binary packages which are specific to a particular
1872 architecture, and <tt>binary-indep</tt> builds
1873 those which are not.
1876 <tt>binary</tt> may be (and commonly is) a target with
1877 no commands which simply depends on
1878 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1881 Both <tt>binary-*</tt> targets should depend on the
1882 <tt>build</tt> target, or on the appropriate
1883 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1884 provided, so that the package is built if it has not
1885 been already. It should then create the relevant
1886 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1887 make their control files and <prgn>dpkg-deb</prgn> to
1888 build them and place them in the parent of the top
1893 Both the <tt>binary-arch</tt> and
1894 <tt>binary-indep</tt> targets <em>must</em> exist.
1895 If one of them has nothing to do (which will always be
1896 the case if the source generates only a single binary
1897 package, whether architecture-dependent or not), it
1898 must still exist and must always succeed.
1902 The <tt>binary</tt> targets must be invoked as
1904 The <prgn>fakeroot</prgn> package often allows one
1905 to build a package correctly even without being
1911 <tag><tt>clean</tt></tag>
1914 This must undo any effects that the <tt>build</tt>
1915 and <tt>binary</tt> targets may have had, except
1916 that it should leave alone any output files created in
1917 the parent directory by a run of a <tt>binary</tt>
1922 If a <tt>build</tt> file is touched at the end of
1923 the <tt>build</tt> target, as suggested above, it
1924 should be removed as the first action that
1925 <tt>clean</tt> performs, so that running
1926 <tt>build</tt> again after an interrupted
1927 <tt>clean</tt> doesn't think that everything is
1932 The <tt>clean</tt> target may need to be
1933 invoked as root if <tt>binary</tt> has been
1934 invoked since the last <tt>clean</tt>, or if
1935 <tt>build</tt> has been invoked as root (since
1936 <tt>build</tt> may create directories, for
1941 <tag><tt>get-orig-source</tt> (optional)</tag>
1944 This target fetches the most recent version of the
1945 original source package from a canonical archive site
1946 (via FTP or WWW, for example), does any necessary
1947 rearrangement to turn it into the original source
1948 tar file format described below, and leaves it in the
1953 This target may be invoked in any directory, and
1954 should take care to clean up any temporary files it
1959 This target is optional, but providing it if
1960 possible is a good idea.
1964 <tag><tt>patch</tt> (optional)</tag>
1967 This target performs whatever additional actions are
1968 required to make the source ready for editing (unpacking
1969 additional upstream archives, applying patches, etc.).
1970 It is recommended to be implemented for any package where
1971 <tt>dpkg-source -x</tt> does not result in source ready
1972 for additional modification. See
1973 <ref id="readmesource">.
1979 The <tt>build</tt>, <tt>binary</tt> and
1980 <tt>clean</tt> targets must be invoked with the current
1981 directory being the package's top-level directory.
1986 Additional targets may exist in <file>debian/rules</file>,
1987 either as published or undocumented interfaces or for the
1988 package's internal use.
1992 The architectures we build on and build for are determined
1993 by <prgn>make</prgn> variables using the utility
1994 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
1995 You can determine the
1996 Debian architecture and the GNU style architecture
1997 specification string for the build machine (the machine type
1998 we are building on) as well as for the host machine (the
1999 machine type we are building for). Here is a list of
2000 supported <prgn>make</prgn> variables:
2001 <list compact="compact">
2003 <tt>DEB_*_ARCH</tt> (the Debian architecture)
2006 <tt>DEB_*_ARCH_CPU</tt> (the Debian CPU name)
2009 <tt>DEB_*_ARCH_OS</tt> (the Debian System name)
2012 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2013 specification string)
2016 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2017 <tt>DEB_*_GNU_TYPE</tt>)
2020 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2021 <tt>DEB_*_GNU_TYPE</tt>)
2023 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2024 the build machine or <tt>HOST</tt> for specification of the
2029 Backward compatibility can be provided in the rules file
2030 by setting the needed variables to suitable default
2031 values; please refer to the documentation of
2032 <prgn>dpkg-architecture</prgn> for details.
2036 It is important to understand that the <tt>DEB_*_ARCH</tt>
2037 string only determines which Debian architecture we are
2038 building on or for. It should not be used to get the CPU
2039 or system information; the <tt>DEB_*_ARCH_CPU</tt> and
2040 <tt>DEB_*_ARCH_OS</tt> variables should be used for that.
2041 GNU style variables should generally only be used with upstream
2045 <sect1 id="debianrules-options">
2046 <heading><file>debian/rules</file> and
2047 <tt>DEB_BUILD_OPTIONS</tt></heading>
2050 Supporting the standardized environment variable
2051 <tt>DEB_BUILD_OPTIONS</tt> is recommended. This variable can
2052 contain several flags to change how a package is compiled and
2053 built. Each flag must be in the form <var>flag</var> or
2054 <var>flag</var>=<var>options</var>. If multiple flags are
2055 given, they must be separated by whitespace.<footnote>
2056 Some packages support any delimiter, but whitespace is the
2057 easiest to parse inside a makefile and avoids ambiguity with
2058 flag values that contain commas.
2060 <var>flag</var> must start with a lowercase letter
2061 (<tt>a-z</tt>) and consist only of lowercase letters,
2062 numbers (<tt>0-9</tt>), and the characters
2063 <tt>-</tt> and <tt>_</tt> (hyphen and underscore).
2064 <var>options</var> must not contain whitespace. The same
2065 tag should not be given multiple times with conflicting
2066 values. Package maintainers may assume that
2067 <tt>DEB_BUILD_OPTIONS</tt> will not contain conflicting tags.
2071 The meaning of the following tags has been standardized:
2075 This tag says to not run any build-time test suite
2076 provided by the package.
2080 The presence of this tag means that the package should
2081 be compiled with a minimum of optimization. For C
2082 programs, it is best to add <tt>-O0</tt> to
2083 <tt>CFLAGS</tt> (although this is usually the default).
2084 Some programs might fail to build or run at this level
2085 of optimization; it may be necessary to use
2086 <tt>-O1</tt>, for example.
2090 This tag means that the debugging symbols should not be
2091 stripped from the binary during installation, so that
2092 debugging information may be included in the package.
2094 <tag>parallel=n</tag>
2096 This tag means that the package should be built using up
2097 to <tt>n</tt> parallel processes if the package build
2098 system supports this.<footnote>
2099 Packages built with <tt>make</tt> can often implement
2100 this by passing the <tt>-j</tt><var>n</var> option to
2103 If the package build system does not support parallel
2104 builds, this string must be ignored. If the package
2105 build system only supports a lower level of concurrency
2106 than <var>n</var>, the package should be built using as
2107 many parallel processes as the package build system
2108 supports. It is up to the package maintainer to decide
2109 whether the package build times are long enough and the
2110 package build system is robust enough to make supporting
2111 parallel builds worthwhile.
2117 Unknown flags must be ignored by <file>debian/rules</file>.
2121 The following makefile snippet is an example of how one may
2122 implement the build options; you will probably have to
2123 massage this example in order to make it work for your
2125 <example compact="compact">
2128 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
2129 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
2130 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
2131 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
2133 ifneq (,$(filter noopt,$(DEB_BUILD_OPTIONS)))
2138 ifeq (,$(filter nostrip,$(DEB_BUILD_OPTIONS)))
2139 INSTALL_PROGRAM += -s
2141 ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2142 NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2143 MAKEFLAGS += -j$(NUMJOBS)
2148 ifeq (,$(filter nocheck,$(DEB_BUILD_OPTIONS)))
2149 # Code to run the package test suite.
2156 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2157 <sect id="substvars">
2158 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2161 When <prgn>dpkg-gencontrol</prgn>,
2162 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2163 generate control files they perform variable substitutions
2164 on their output just before writing it. Variable
2165 substitutions have the form <tt>${<var>variable</var>}</tt>.
2166 The optional file <file>debian/substvars</file> contains
2167 variable substitutions to be used; variables can also be set
2168 directly from <file>debian/rules</file> using the <tt>-V</tt>
2169 option to the source packaging commands, and certain
2170 predefined variables are also available.
2174 The <file>debian/substvars</file> file is usually generated and
2175 modified dynamically by <file>debian/rules</file> targets, in
2176 which case it must be removed by the <tt>clean</tt> target.
2180 See <manref name="deb-substvars" section="5"> for full
2181 details about source variable substitutions, including the
2182 format of <file>debian/substvars</file>.</p>
2185 <sect id="debianwatch">
2186 <heading>Optional upstream source location: <file>debian/watch</file></heading>
2189 This is an optional, recommended control file for the
2190 <tt>uscan</tt> utility which defines how to automatically
2191 scan ftp or http sites for newly available updates of the
2192 package. This is used by <url id="
2193 http://dehs.alioth.debian.org/"> and other Debian QA tools
2194 to help with quality control and maintenance of the
2195 distribution as a whole.
2200 <sect id="debianfiles">
2201 <heading>Generated files list: <file>debian/files</file></heading>
2204 This file is not a permanent part of the source tree; it
2205 is used while building packages to record which files are
2206 being generated. <prgn>dpkg-genchanges</prgn> uses it
2207 when it generates a <file>.changes</file> file.
2211 It should not exist in a shipped source package, and so it
2212 (and any backup files or temporary files such as
2213 <file>files.new</file><footnote>
2214 <file>files.new</file> is used as a temporary file by
2215 <prgn>dpkg-gencontrol</prgn> and
2216 <prgn>dpkg-distaddfile</prgn> - they write a new
2217 version of <tt>files</tt> here before renaming it,
2218 to avoid leaving a corrupted copy if an error
2220 </footnote>) should be removed by the
2221 <tt>clean</tt> target. It may also be wise to
2222 ensure a fresh start by emptying or removing it at the
2223 start of the <tt>binary</tt> target.
2227 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2228 package, it adds an entry to <file>debian/files</file> for the
2229 <file>.deb</file> file that will be created when <tt>dpkg-deb
2230 --build</tt> is run for that binary package. So for most
2231 packages all that needs to be done with this file is to
2232 delete it in the <tt>clean</tt> target.
2236 If a package upload includes files besides the source
2237 package and any binary packages whose control files were
2238 made with <prgn>dpkg-gencontrol</prgn> then they should be
2239 placed in the parent of the package's top-level directory
2240 and <prgn>dpkg-distaddfile</prgn> should be called to add
2241 the file to the list in <file>debian/files</file>.</p>
2244 <sect id="embeddedfiles">
2245 <heading>Convenience copies of code</heading>
2248 Some software packages include in their distribution convenience
2249 copies of code from other software packages, generally so that
2250 users compiling from source don't have to download multiple
2251 packages. Debian packages should not make use of these
2252 convenience copies unless the included package is explicitly
2253 intended to be used in this way.<footnote>
2254 For example, parts of the GNU build system work like this.
2256 If the included code is already in the Debian archive in the
2257 form of a library, the Debian packaging should ensure that
2258 binary packages reference the libraries already in Debian and
2259 the convenience copy is not used. If the included code is not
2260 already in Debian, it should be packaged separately as a
2261 prerequisite if possible.
2263 Having multiple copies of the same code in Debian is
2264 inefficient, often creates either static linking or shared
2265 library conflicts, and, most importantly, increases the
2266 difficulty of handling security vulnerabilities in the
2272 <sect id="readmesource">
2273 <heading>Source package handling:
2274 <file>debian/README.source</file></heading>
2277 If running <prgn>dpkg-source -x</prgn> on a source package
2278 doesn't produce the source of the package, ready for editing,
2279 and allow one to make changes and run
2280 <prgn>dpkg-buildpackage</prgn> to produce a modified package
2281 without taking any additional steps, creating a
2282 <file>debian/README.source</file> documentation file is
2283 recommended. This file should explain how to do all of the
2286 <item>Generate the fully patched source, in a form ready for
2287 editing, that would be built to create Debian
2288 packages. Doing this with a <tt>patch</tt> target in
2289 <file>debian/rules</file> is recommended; see
2290 <ref id="debianrules">.</item>
2291 <item>Modify the source and save those modifications so that
2292 they will be applied when building the package.</item>
2293 <item>Remove source modifications that are currently being
2294 applied when building the package.</item>
2295 <item>Optionally, document what steps are necessary to
2296 upgrade the Debian source package to a new upstream version,
2297 if applicable.</item>
2299 This explanation should include specific commands and mention
2300 any additional required Debian packages. It should not assume
2301 familiarity with any specific Debian packaging system or patch
2306 This explanation may refer to a documentation file installed by
2307 one of the package's build dependencies provided that the
2308 referenced documentation clearly explains these tasks and is not
2309 a general reference manual.
2313 <file>debian/README.source</file> may also include any other
2314 information that would be helpful to someone modifying the
2315 source package. Even if the package doesn't fit the above
2316 description, maintainers are encouraged to document in a
2317 <file>debian/README.source</file> file any source package with a
2318 particularly complex or unintuitive source layout or build
2319 system (for example, a package that builds the same source
2320 multiple times to generate different binary packages).
2326 <chapt id="controlfields">
2327 <heading>Control files and their fields</heading>
2330 The package management system manipulates data represented in
2331 a common format, known as <em>control data</em>, stored in
2332 <em>control files</em>.
2333 Control files are used for source packages, binary packages and
2334 the <file>.changes</file> files which control the installation
2335 of uploaded files<footnote>
2336 <prgn>dpkg</prgn>'s internal databases are in a similar
2341 <sect id="controlsyntax">
2342 <heading>Syntax of control files</heading>
2345 A control file consists of one or more paragraphs of
2347 The paragraphs are also sometimes referred to as stanzas.
2349 The paragraphs are separated by blank lines. Some control
2350 files allow only one paragraph; others allow several, in
2351 which case each paragraph usually refers to a different
2352 package. (For example, in source packages, the first
2353 paragraph refers to the source package, and later paragraphs
2354 refer to binary packages generated from the source.)
2358 Each paragraph consists of a series of data fields; each
2359 field consists of the field name, followed by a colon and
2360 then the data/value associated with that field. It ends at
2361 the end of the (logical) line. Horizontal whitespace
2362 (spaces and tabs) may occur immediately before or after the
2363 value and is ignored there; it is conventional to put a
2364 single space after the colon. For example, a field might
2366 <example compact="compact">
2369 the field name is <tt>Package</tt> and the field value
2374 Many fields' values may span several lines; in this case
2375 each continuation line must start with a space or a tab.
2376 Any trailing spaces or tabs at the end of individual
2377 lines of a field value are ignored.
2381 In fields where it is specified that lines may not wrap,
2382 only a single line of data is allowed and whitespace is not
2383 significant in a field body. Whitespace must not appear
2384 inside names (of packages, architectures, files or anything
2385 else) or version numbers, or between the characters of
2386 multi-character version relationships.
2390 Field names are not case-sensitive, but it is usual to
2391 capitalize the field names using mixed case as shown below.
2392 Field values are case-sensitive unless the description of the
2393 field says otherwise.
2397 Blank lines, or lines consisting only of spaces and tabs,
2398 are not allowed within field values or between fields - that
2399 would mean a new paragraph.
2403 All control files must be encoded in UTF-8.
2407 <sect id="sourcecontrolfiles">
2408 <heading>Source package control files -- <file>debian/control</file></heading>
2411 The <file>debian/control</file> file contains the most vital
2412 (and version-independent) information about the source package
2413 and about the binary packages it creates.
2417 The first paragraph of the control file contains information about
2418 the source package in general. The subsequent sets each describe a
2419 binary package that the source tree builds.
2423 The fields in the general paragraph (the first one, for the source
2426 <list compact="compact">
2427 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2428 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2429 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2430 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2431 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2432 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2433 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2434 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2439 The fields in the binary package paragraphs are:
2441 <list compact="compact">
2442 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2443 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2444 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2445 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2446 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2447 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2448 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2449 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2454 The syntax and semantics of the fields are described below.
2460 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2461 generate control files for binary packages (see below), by
2462 <prgn>dpkg-genchanges</prgn> to generate the
2463 <tt>.changes</tt> file to accompany the upload, and by
2464 <prgn>dpkg-source</prgn> when it creates the
2465 <file>.dsc</file> source control file as part of a source
2466 archive. Many fields are permitted to span multiple lines in
2467 <file>debian/control</file> but not in any other control
2468 file. These tools are responsible for removing the line
2469 breaks from such fields when using fields from
2470 <file>debian/control</file> to generate other control files.
2474 The fields here may contain variable references - their
2475 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2476 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2477 when they generate output control files.
2478 See <ref id="substvars"> for details.
2482 In addition to the control file syntax described <qref
2483 id="controlsyntax">above</qref>, this file may also contain
2484 comment lines starting with <tt>#</tt> without any preceding
2485 whitespace. All such lines are ignored, even in the middle of
2486 continuation lines for a multiline field, and do not end a
2492 <sect id="binarycontrolfiles">
2493 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2496 The <file>DEBIAN/control</file> file contains the most vital
2497 (and version-dependent) information about a binary package.
2501 The fields in this file are:
2503 <list compact="compact">
2504 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2505 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2506 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2507 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2508 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2509 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2510 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2511 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2512 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2513 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2514 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2515 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2520 <sect id="debiansourcecontrolfiles">
2521 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2524 This file contains a series of fields, identified and
2525 separated just like the fields in the control file of
2526 a binary package. The fields are listed below; their
2527 syntax is described above, in <ref id="pkg-controlfields">.
2529 <list compact="compact">
2530 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2531 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2532 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2533 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2534 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2535 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2536 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2537 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2538 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2539 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2540 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2545 The source package control file is generated by
2546 <prgn>dpkg-source</prgn> when it builds the source
2547 archive, from other files in the source package,
2548 described above. When unpacking, it is checked against
2549 the files and directories in the other parts of the
2555 <sect id="debianchangesfiles">
2556 <heading>Debian changes files -- <file>.changes</file></heading>
2559 The .changes files are used by the Debian archive maintenance
2560 software to process updates to packages. They contain one
2561 paragraph which contains information from the
2562 <tt>debian/control</tt> file and other data about the
2563 source package gathered via <tt>debian/changelog</tt>
2564 and <tt>debian/rules</tt>.
2568 The fields in this file are:
2570 <list compact="compact">
2571 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2572 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2573 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2574 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2575 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2576 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2577 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2578 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2579 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2580 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2581 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2582 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2583 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2584 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2589 <sect id="controlfieldslist">
2590 <heading>List of fields</heading>
2592 <sect1 id="f-Source">
2593 <heading><tt>Source</tt></heading>
2596 This field identifies the source package name.
2600 In <file>debian/control</file> or a <file>.dsc</file> file,
2601 this field must contain only the name of the source package.
2605 In a binary package control file or a <file>.changes</file>
2606 file, the source package name may be followed by a version
2607 number in parentheses<footnote>
2608 It is customary to leave a space after the package name
2609 if a version number is specified.
2611 This version number may be omitted (and is, by
2612 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2613 the <tt>Version</tt> field of the binary package in
2614 question. The field itself may be omitted from a binary
2615 package control file when the source package has the same
2616 name and version as the binary package.
2620 Package names (both source and binary,
2621 see <ref id="f-Package">) must consist only of lower case
2622 letters (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus
2623 (<tt>+</tt>) and minus (<tt>-</tt>) signs, and periods
2624 (<tt>.</tt>). They must be at least two characters long and
2625 must start with an alphanumeric character.
2629 <sect1 id="f-Maintainer">
2630 <heading><tt>Maintainer</tt></heading>
2633 The package maintainer's name and email address. The name
2634 should come first, then the email address inside angle
2635 brackets <tt><></tt> (in RFC822 format).
2639 If the maintainer's name contains a full stop then the
2640 whole field will not work directly as an email address due
2641 to a misfeature in the syntax specified in RFC822; a
2642 program using this field as an address must check for this
2643 and correct the problem if necessary (for example by
2644 putting the name in round brackets and moving it to the
2645 end, and bringing the email address forward).
2649 <sect1 id="f-Uploaders">
2650 <heading><tt>Uploaders</tt></heading>
2653 List of the names and email addresses of co-maintainers of
2654 the package, if any. If the package has other maintainers
2655 beside the one named in the
2656 <qref id="f-Maintainer">Maintainer field</qref>, their
2657 names and email addresses should be listed here. The
2658 format is the same as that of the Maintainer tag, and
2659 multiple entries should be comma separated. Currently,
2660 this field is restricted to a single line of data. This
2661 is an optional field.
2664 Any parser that interprets the Uploaders field in
2665 <file>debian/control</file> must permit it to span multiple
2666 lines. Line breaks in an Uploaders field that spans multiple
2667 lines are not significant and the semantics of the field are
2668 the same as if the line breaks had not been present.
2672 <sect1 id="f-Changed-By">
2673 <heading><tt>Changed-By</tt></heading>
2676 The name and email address of the person who changed the
2677 said package. Usually the name of the maintainer.
2678 All the rules for the Maintainer field apply here, too.
2682 <sect1 id="f-Section">
2683 <heading><tt>Section</tt></heading>
2686 This field specifies an application area into which the package
2687 has been classified. See <ref id="subsections">.
2691 When it appears in the <file>debian/control</file> file,
2692 it gives the value for the subfield of the same name in
2693 the <tt>Files</tt> field of the <file>.changes</file> file.
2694 It also gives the default for the same field in the binary
2699 <sect1 id="f-Priority">
2700 <heading><tt>Priority</tt></heading>
2703 This field represents how important it is that the user
2704 have the package installed. See <ref id="priorities">.
2708 When it appears in the <file>debian/control</file> file,
2709 it gives the value for the subfield of the same name in
2710 the <tt>Files</tt> field of the <file>.changes</file> file.
2711 It also gives the default for the same field in the binary
2716 <sect1 id="f-Package">
2717 <heading><tt>Package</tt></heading>
2720 The name of the binary package.
2724 Binary package names must follow the same syntax and
2725 restrictions as source package names. See <ref id="f-Source">
2730 <sect1 id="f-Architecture">
2731 <heading><tt>Architecture</tt></heading>
2734 Depending on context and the control file used, the
2735 <tt>Architecture</tt> field can include the following sets of
2739 A unique single word identifying a Debian machine
2740 architecture as described in <ref id="arch-spec">.
2743 An architecture wildcard identifying a set of Debian
2744 machine architectures, see <ref id="arch-wildcard-spec">.
2745 <tt>any</tt> matches all Debian machine architectures
2746 and is the most frequently used.
2749 <tt>all</tt>, which indicates an
2750 architecture-independent package.
2753 <tt>source</tt>, which indicates a source package.
2759 In the main <file>debian/control</file> file in the source
2760 package, this field may contain the special
2761 value <tt>all</tt>, the special architecture
2762 wildcard <tt>any</tt>, or a list of specific and wildcard
2763 architectures separated by spaces. If <tt>all</tt>
2764 or <tt>any</tt> appears, that value must be the entire
2765 contents of the field. Most packages will use
2766 either <tt>all</tt> or <tt>any</tt>.
2770 Specifying a specific list of architectures indicates that the
2771 source will build an architecture-dependent package only on
2772 architectures included in the list. Specifying a list of
2773 architecture wildcards indicates that the source will build an
2774 architecture-dependent package on only those architectures
2775 that match any of the specified architecture wildcards.
2776 Specifying a list of architectures or architecture wildcards
2777 other than <tt>any</tt> is for the minority of cases where a
2778 program is not portable or is not useful on some
2779 architectures. Where possible, the program should be made
2784 In the source package control file <file>.dsc</file>, this
2785 field may contain either the architecture
2786 wildcard <tt>any</tt> or a list of architectures and
2787 architecture wildcards separated by spaces. If a list is
2788 given, it may include (or consist solely of) the special
2789 value <tt>all</tt>. In other words, in <file>.dsc</file>
2790 files unlike the <file>debian/control</file>, <tt>all</tt> may
2791 occur in combination with specific architectures.
2792 The <tt>Architecture</tt> field in the source package control
2793 file <file>.dsc</file> is generally constructed from
2794 the <tt>Architecture</tt> fields in
2795 the <file>debian/control</file> in the source package.
2799 Specifying <tt>any</tt> indicates that the source package
2800 isn't dependent on any particular architecture and should
2801 compile fine on any one. The produced binary package(s)
2802 will either be specific to whatever the current build
2803 architecture is or will be architecture-independent.
2807 Specifying only <tt>all</tt> indicates that the source package
2808 will only build architecture-independent packages. If this is
2809 the case, <tt>all</tt> must be used rather than <tt>any</tt>;
2810 <tt>any</tt> implies that the source package will build at
2811 least one architecture-dependent package.
2815 Specifying a list of architectures or architecture wildcards
2816 indicates that the source will build an architecture-dependent
2817 package, and will only work correctly on the listed or
2818 matching architectures. If the source package also builds at
2819 least one architecture-independent package, <tt>all</tt> will
2820 also be included in the list.
2824 In a <file>.changes</file> file, the <tt>Architecture</tt>
2825 field lists the architecture(s) of the package(s) currently
2826 being uploaded. This will be a list; if the source for the
2827 package is also being uploaded, the special
2828 entry <tt>source</tt> is also present. <tt>all</tt> will be
2829 present if any architecture-independent packages are being
2830 uploaded. Architecture wildcards such as <tt>any</tt> must
2831 never occur in the <tt>Architecture</tt> field in
2832 the <file>.changes</file> file.
2836 See <ref id="debianrules"> for information on how to get
2837 the architecture for the build process.
2841 <sect1 id="f-Essential">
2842 <heading><tt>Essential</tt></heading>
2845 This is a boolean field which may occur only in the
2846 control file of a binary package or in a per-package fields
2847 paragraph of a main source control data file.
2851 If set to <tt>yes</tt> then the package management system
2852 will refuse to remove the package (upgrading and replacing
2853 it is still possible). The other possible value is <tt>no</tt>,
2854 which is the same as not having the field at all.
2859 <heading>Package interrelationship fields:
2860 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2861 <tt>Recommends</tt>, <tt>Suggests</tt>,
2862 <tt>Breaks</tt>, <tt>Conflicts</tt>,
2863 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2867 These fields describe the package's relationships with
2868 other packages. Their syntax and semantics are described
2869 in <ref id="relationships">.</p>
2872 <sect1 id="f-Standards-Version">
2873 <heading><tt>Standards-Version</tt></heading>
2876 The most recent version of the standards (the policy
2877 manual and associated texts) with which the package
2882 The version number has four components: major and minor
2883 version number and major and minor patch level. When the
2884 standards change in a way that requires every package to
2885 change the major number will be changed. Significant
2886 changes that will require work in many packages will be
2887 signaled by a change to the minor number. The major patch
2888 level will be changed for any change to the meaning of the
2889 standards, however small; the minor patch level will be
2890 changed when only cosmetic, typographical or other edits
2891 are made which neither change the meaning of the document
2892 nor affect the contents of packages.
2896 Thus only the first three components of the policy version
2897 are significant in the <em>Standards-Version</em> control
2898 field, and so either these three components or all four
2899 components may be specified.<footnote>
2900 In the past, people specified the full version number
2901 in the Standards-Version field, for example "2.3.0.0".
2902 Since minor patch-level changes don't introduce new
2903 policy, it was thought it would be better to relax
2904 policy and only require the first 3 components to be
2905 specified, in this example "2.3.0". All four
2906 components may still be used if someone wishes to do so.
2912 <sect1 id="f-Version">
2913 <heading><tt>Version</tt></heading>
2916 The version number of a package. The format is:
2917 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2921 The three components here are:
2923 <tag><var>epoch</var></tag>
2926 This is a single (generally small) unsigned integer. It
2927 may be omitted, in which case zero is assumed. If it is
2928 omitted then the <var>upstream_version</var> may not
2933 It is provided to allow mistakes in the version numbers
2934 of older versions of a package, and also a package's
2935 previous version numbering schemes, to be left behind.
2939 <tag><var>upstream_version</var></tag>
2942 This is the main part of the version number. It is
2943 usually the version number of the original ("upstream")
2944 package from which the <file>.deb</file> file has been made,
2945 if this is applicable. Usually this will be in the same
2946 format as that specified by the upstream author(s);
2947 however, it may need to be reformatted to fit into the
2948 package management system's format and comparison
2953 The comparison behavior of the package management system
2954 with respect to the <var>upstream_version</var> is
2955 described below. The <var>upstream_version</var>
2956 portion of the version number is mandatory.
2960 The <var>upstream_version</var> may contain only
2961 alphanumerics<footnote>
2962 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2964 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2965 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
2966 tilde) and should start with a digit. If there is no
2967 <var>debian_revision</var> then hyphens are not allowed;
2968 if there is no <var>epoch</var> then colons are not
2973 <tag><var>debian_revision</var></tag>
2976 This part of the version number specifies the version of
2977 the Debian package based on the upstream version. It
2978 may contain only alphanumerics and the characters
2979 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
2980 tilde) and is compared in the same way as the
2981 <var>upstream_version</var> is.
2985 It is optional; if it isn't present then the
2986 <var>upstream_version</var> may not contain a hyphen.
2987 This format represents the case where a piece of
2988 software was written specifically to be turned into a
2989 Debian package, and so there is only one "debianisation"
2990 of it and therefore no revision indication is required.
2994 It is conventional to restart the
2995 <var>debian_revision</var> at <tt>1</tt> each time the
2996 <var>upstream_version</var> is increased.
3000 The package management system will break the version
3001 number apart at the last hyphen in the string (if there
3002 is one) to determine the <var>upstream_version</var> and
3003 <var>debian_revision</var>. The absence of a
3004 <var>debian_revision</var> is equivalent to a
3005 <var>debian_revision</var> of <tt>0</tt>.
3012 When comparing two version numbers, first the <var>epoch</var>
3013 of each are compared, then the <var>upstream_version</var> if
3014 <var>epoch</var> is equal, and then <var>debian_revision</var>
3015 if <var>upstream_version</var> is also equal.
3016 <var>epoch</var> is compared numerically. The
3017 <var>upstream_version</var> and <var>debian_revision</var>
3018 parts are compared by the package management system using the
3019 following algorithm:
3023 The strings are compared from left to right.
3027 First the initial part of each string consisting entirely of
3028 non-digit characters is determined. These two parts (one of
3029 which may be empty) are compared lexically. If a difference
3030 is found it is returned. The lexical comparison is a
3031 comparison of ASCII values modified so that all the letters
3032 sort earlier than all the non-letters and so that a tilde
3033 sorts before anything, even the end of a part. For example,
3034 the following parts are in sorted order from earliest to
3035 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
3036 <tt>a</tt>.<footnote>
3037 One common use of <tt>~</tt> is for upstream pre-releases.
3038 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
3039 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
3044 Then the initial part of the remainder of each string which
3045 consists entirely of digit characters is determined. The
3046 numerical values of these two parts are compared, and any
3047 difference found is returned as the result of the comparison.
3048 For these purposes an empty string (which can only occur at
3049 the end of one or both version strings being compared) counts
3054 These two steps (comparing and removing initial non-digit
3055 strings and initial digit strings) are repeated until a
3056 difference is found or both strings are exhausted.
3060 Note that the purpose of epochs is to allow us to leave behind
3061 mistakes in version numbering, and to cope with situations
3062 where the version numbering scheme changes. It is
3063 <em>not</em> intended to cope with version numbers containing
3064 strings of letters which the package management system cannot
3065 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
3066 silly orderings.<footnote>
3067 The author of this manual has heard of a package whose
3068 versions went <tt>1.1</tt>, <tt>1.2</tt>, <tt>1.3</tt>,
3069 <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>, <tt>2</tt> and so
3075 <sect1 id="f-Description">
3076 <heading><tt>Description</tt></heading>
3079 In a source or binary control file, the <tt>Description</tt>
3080 field contains a description of the binary package, consisting
3081 of two parts, the synopsis or the short description, and the
3082 long description. The field's format is as follows:
3087 Description: <single line synopsis>
3088 <extended description over several lines>
3093 The lines in the extended description can have these formats:
3099 Those starting with a single space are part of a paragraph.
3100 Successive lines of this form will be word-wrapped when
3101 displayed. The leading space will usually be stripped off.
3105 Those starting with two or more spaces. These will be
3106 displayed verbatim. If the display cannot be panned
3107 horizontally, the displaying program will line wrap them "hard"
3108 (i.e., without taking account of word breaks). If it can they
3109 will be allowed to trail off to the right. None, one or two
3110 initial spaces may be deleted, but the number of spaces
3111 deleted from each line will be the same (so that you can have
3112 indenting work correctly, for example).
3116 Those containing a single space followed by a single full stop
3117 character. These are rendered as blank lines. This is the
3118 <em>only</em> way to get a blank line<footnote>
3119 Completely empty lines will not be rendered as blank lines.
3120 Instead, they will cause the parser to think you're starting
3121 a whole new record in the control file, and will therefore
3122 likely abort with an error.
3127 Those containing a space, a full stop and some more characters.
3128 These are for future expansion. Do not use them.
3134 Do not use tab characters. Their effect is not predictable.
3138 See <ref id="descriptions"> for further information on this.
3142 In a <file>.changes</file> file, the <tt>Description</tt>
3143 field contains a summary of the descriptions for the packages
3144 being uploaded. For this case, the first line of the field
3145 value (the part on the same line as <tt>Description:</tt>) is
3146 always empty. The content of the field is expressed as
3147 continuation lines, one line per package. Each line is
3148 indented by one space and contains the name of a binary
3149 package, a space, a hyphen (<tt>-</tt>), a space, and the
3150 short description line from that package.
3154 <sect1 id="f-Distribution">
3155 <heading><tt>Distribution</tt></heading>
3158 In a <file>.changes</file> file or parsed changelog output
3159 this contains the (space-separated) name(s) of the
3160 distribution(s) where this version of the package should
3161 be installed. Valid distributions are determined by the
3162 archive maintainers.<footnote>
3163 Example distribution names in the Debian archive used in
3164 <file>.changes</file> files are:
3165 <taglist compact="compact">
3166 <tag><em>unstable</em></tag>
3168 This distribution value refers to the
3169 <em>developmental</em> part of the Debian distribution
3170 tree. Most new packages, new upstream versions of
3171 packages and bug fixes go into the <em>unstable</em>
3175 <tag><em>experimental</em></tag>
3177 The packages with this distribution value are deemed
3178 by their maintainers to be high risk. Oftentimes they
3179 represent early beta or developmental packages from
3180 various sources that the maintainers want people to
3181 try, but are not ready to be a part of the other parts
3182 of the Debian distribution tree.
3187 Others are used for updating stable releases or for
3188 security uploads. More information is available in the
3189 Debian Developer's Reference, section "The Debian
3193 The Debian archive software only supports listing a single
3194 distribution. Migration of packages to other distributions is
3195 handled outside of the upload process.
3200 <heading><tt>Date</tt></heading>
3203 This field includes the date the package was built or last edited.
3207 The value of this field is usually extracted from the
3208 <file>debian/changelog</file> file - see
3209 <ref id="dpkgchangelog">).
3213 <sect1 id="f-Format">
3214 <heading><tt>Format</tt></heading>
3217 This field specifies a format revision for the file.
3218 The most current format described in the Policy Manual
3219 is version <strong>1.5</strong>. The syntax of the
3220 format value is the same as that of a package version
3221 number except that no epoch or Debian revision is allowed
3222 - see <ref id="f-Version">.
3226 <sect1 id="f-Urgency">
3227 <heading><tt>Urgency</tt></heading>
3230 This is a description of how important it is to upgrade to
3231 this version from previous ones. It consists of a single
3232 keyword taking one of the values <tt>low</tt>,
3233 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3234 <tt>critical</tt><footnote>
3235 Other urgency values are supported with configuration
3236 changes in the archive software but are not used in Debian.
3237 The urgency affects how quickly a package will be considered
3238 for inclusion into the <tt>testing</tt> distribution and
3239 gives an indication of the importance of any fixes included
3240 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3241 treated as synonymous.
3242 </footnote> (not case-sensitive) followed by an optional
3243 commentary (separated by a space) which is usually in
3244 parentheses. For example:
3247 Urgency: low (HIGH for users of diversions)
3253 The value of this field is usually extracted from the
3254 <file>debian/changelog</file> file - see
3255 <ref id="dpkgchangelog">.
3259 <sect1 id="f-Changes">
3260 <heading><tt>Changes</tt></heading>
3263 This field contains the human-readable changes data, describing
3264 the differences between the last version and the current one.
3268 The first line of the field value (the part on the same line
3269 as <tt>Changes:</tt>) is always empty. The content of the
3270 field is expressed as continuation lines, with each line
3271 indented by at least one space. Blank lines must be
3272 represented by a line consisting only of a space and a full
3277 The value of this field is usually extracted from the
3278 <file>debian/changelog</file> file - see
3279 <ref id="dpkgchangelog">).
3283 Each version's change information should be preceded by a
3284 "title" line giving at least the version, distribution(s)
3285 and urgency, in a human-readable way.
3289 If data from several versions is being returned the entry
3290 for the most recent version should be returned first, and
3291 entries should be separated by the representation of a
3292 blank line (the "title" line may also be followed by the
3293 representation of a blank line).
3297 <sect1 id="f-Binary">
3298 <heading><tt>Binary</tt></heading>
3301 This field is a list of binary packages. Its syntax and
3302 meaning varies depending on the control file in which it
3307 When it appears in the <file>.dsc</file> file, it lists binary
3308 packages which a source package can produce, separated by
3310 A space after each comma is conventional.
3311 </footnote>. It may span multiple lines. The source package
3312 does not necessarily produce all of these binary packages for
3313 every architecture. The source control file doesn't contain
3314 details of which architectures are appropriate for which of
3315 the binary packages.
3319 When it appears in a <file>.changes</file> file, it lists the
3320 names of the binary packages being uploaded, separated by
3321 whitespace (not commas). It may span multiple lines.
3325 <sect1 id="f-Installed-Size">
3326 <heading><tt>Installed-Size</tt></heading>
3329 This field appears in the control files of binary packages,
3330 and in the <file>Packages</file> files. It gives an estimate
3331 of the total amount of disk space required to install the
3332 named package. Actual installed size may vary based on block
3333 size, file system properties, or actions taken by package
3338 The disk space is given as the integer value of the estimated
3339 installed size in bytes, divided by 1024 and rounded up.
3343 <sect1 id="f-Files">
3344 <heading><tt>Files</tt></heading>
3347 This field contains a list of files with information about
3348 each one. The exact information and syntax varies with
3353 In all cases, Files is a multiline field. The first line of
3354 the field value (the part on the same line as <tt>Files:</tt>)
3355 is always empty. The content of the field is expressed as
3356 continuation lines, one line per file. Each line must be
3357 indented by one space and contain a number of sub-fields,
3358 separated by spaces, as described below.
3362 In the <file>.dsc</file> file, each line contains the MD5
3363 checksum, size and filename of the tar file and (if
3364 applicable) diff file which make up the remainder of the
3365 source package<footnote>
3366 That is, the parts which are not the <tt>.dsc</tt>.
3367 </footnote>. For example:
3370 c6f698f19f2a2aa07dbb9bbda90a2754 571925 example_1.2.orig.tar.gz
3371 938512f08422f3509ff36f125f5873ba 6220 example_1.2-1.diff.gz
3373 The exact forms of the filenames are described
3374 in <ref id="pkg-sourcearchives">.
3378 In the <file>.changes</file> file this contains one line per
3379 file being uploaded. Each line contains the MD5 checksum,
3380 size, section and priority and the filename. For example:
3383 4c31ab7bfc40d3cf49d7811987390357 1428 text extra example_1.2-1.dsc
3384 c6f698f19f2a2aa07dbb9bbda90a2754 571925 text extra example_1.2.orig.tar.gz
3385 938512f08422f3509ff36f125f5873ba 6220 text extra example_1.2-1.diff.gz
3386 7c98fe853b3bbb47a00e5cd129b6cb56 703542 text extra example_1.2-1_i386.deb
3388 The <qref id="f-Section">section</qref>
3389 and <qref id="f-Priority">priority</qref> are the values of
3390 the corresponding fields in the main source control file. If
3391 no section or priority is specified then <tt>-</tt> should be
3392 used, though section and priority values must be specified for
3393 new packages to be installed properly.
3397 The special value <tt>byhand</tt> for the section in a
3398 <tt>.changes</tt> file indicates that the file in question
3399 is not an ordinary package file and must by installed by
3400 hand by the distribution maintainers. If the section is
3401 <tt>byhand</tt> the priority should be <tt>-</tt>.
3405 If a new Debian revision of a package is being shipped and
3406 no new original source archive is being distributed the
3407 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3408 entry for the original source archive
3409 <file><var>package</var>_<var>upstream-version</var>.orig.tar.gz</file>,
3410 but the <file>.changes</file> file should leave it out. In
3411 this case the original source archive on the distribution
3412 site must match exactly, byte-for-byte, the original
3413 source archive which was used to generate the
3414 <file>.dsc</file> file and diff which are being uploaded.</p>
3417 <sect1 id="f-Closes">
3418 <heading><tt>Closes</tt></heading>
3421 A space-separated list of bug report numbers that the upload
3422 governed by the .changes file closes.
3426 <sect1 id="f-Homepage">
3427 <heading><tt>Homepage</tt></heading>
3430 The URL of the web site for this package, preferably (when
3431 applicable) the site from which the original source can be
3432 obtained and any additional upstream documentation or
3433 information may be found. The content of this field is a
3434 simple URL without any surrounding characters such as
3442 <heading>User-defined fields</heading>
3445 Additional user-defined fields may be added to the
3446 source package control file. Such fields will be
3447 ignored, and not copied to (for example) binary or
3448 source package control files or upload control files.
3452 If you wish to add additional unsupported fields to
3453 these output files you should use the mechanism
3458 Fields in the main source control information file with
3459 names starting <tt>X</tt>, followed by one or more of
3460 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3461 be copied to the output files. Only the part of the
3462 field name after the hyphen will be used in the output
3463 file. Where the letter <tt>B</tt> is used the field
3464 will appear in binary package control files, where the
3465 letter <tt>S</tt> is used in source package control
3466 files and where <tt>C</tt> is used in upload control
3467 (<tt>.changes</tt>) files.
3471 For example, if the main source information control file
3474 XBS-Comment: I stand between the candle and the star.
3476 then the binary and source package control files will contain the
3479 Comment: I stand between the candle and the star.
3488 <chapt id="maintainerscripts">
3489 <heading>Package maintainer scripts and installation procedure</heading>
3492 <heading>Introduction to package maintainer scripts</heading>
3495 It is possible to supply scripts as part of a package which
3496 the package management system will run for you when your
3497 package is installed, upgraded or removed.
3501 These scripts are the files <prgn>preinst</prgn>,
3502 <prgn>postinst</prgn>, <prgn>prerm</prgn> and
3503 <prgn>postrm</prgn> in the control area of the package.
3504 They must be proper executable files; if they are scripts
3505 (which is recommended), they must start with the usual
3506 <tt>#!</tt> convention. They should be readable and
3507 executable by anyone, and must not be world-writable.
3511 The package management system looks at the exit status from
3512 these scripts. It is important that they exit with a
3513 non-zero status if there is an error, so that the package
3514 management system can stop its processing. For shell
3515 scripts this means that you <em>almost always</em> need to
3516 use <tt>set -e</tt> (this is usually true when writing shell
3517 scripts, in fact). It is also important, of course, that
3518 they exit with a zero status if everything went well.
3522 Additionally, packages interacting with users using
3523 <tt>debconf</tt> in the <prgn>postinst</prgn> script should
3524 install a <prgn>config</prgn> script in the control area,
3525 see <ref id="maintscriptprompt"> for details.
3529 When a package is upgraded a combination of the scripts from
3530 the old and new packages is called during the upgrade
3531 procedure. If your scripts are going to be at all
3532 complicated you need to be aware of this, and may need to
3533 check the arguments to your scripts.
3537 Broadly speaking the <prgn>preinst</prgn> is called before
3538 (a particular version of) a package is installed, and the
3539 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3540 before (a version of) a package is removed and the
3541 <prgn>postrm</prgn> afterwards.
3545 Programs called from maintainer scripts should not normally
3546 have a path prepended to them. Before installation is
3547 started, the package management system checks to see if the
3548 programs <prgn>ldconfig</prgn>,
3549 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3550 and <prgn>update-rc.d</prgn> can be found via the
3551 <tt>PATH</tt> environment variable. Those programs, and any
3552 other program that one would expect to be in the
3553 <tt>PATH</tt>, should thus be invoked without an absolute
3554 pathname. Maintainer scripts should also not reset the
3555 <tt>PATH</tt>, though they might choose to modify it by
3556 prepending or appending package-specific directories. These
3557 considerations really apply to all shell scripts.</p>
3560 <sect id="idempotency">
3561 <heading>Maintainer scripts idempotency</heading>
3564 It is necessary for the error recovery procedures that the
3565 scripts be idempotent. This means that if it is run
3566 successfully, and then it is called again, it doesn't bomb
3567 out or cause any harm, but just ensures that everything is
3568 the way it ought to be. If the first call failed, or
3569 aborted half way through for some reason, the second call
3570 should merely do the things that were left undone the first
3571 time, if any, and exit with a success status if everything
3573 This is so that if an error occurs, the user interrupts
3574 <prgn>dpkg</prgn> or some other unforeseen circumstance
3575 happens you don't leave the user with a badly-broken
3576 package when <prgn>dpkg</prgn> attempts to repeat the
3582 <sect id="controllingterminal">
3583 <heading>Controlling terminal for maintainer scripts</heading>
3586 Maintainer scripts are not guaranteed to run with a controlling
3587 terminal and may not be able to interact with the user. They
3588 must be able to fall back to noninteractive behavior if no
3589 controlling terminal is available. Maintainer scripts that
3590 prompt via a program conforming to the Debian Configuration
3591 Management Specification (see <ref id="maintscriptprompt">) may
3592 assume that program will handle falling back to noninteractive
3597 For high-priority prompts without a reasonable default answer,
3598 maintainer scripts may abort if there is no controlling
3599 terminal. However, this situation should be avoided if at all
3600 possible, since it prevents automated or unattended installs.
3601 In most cases, users will consider this to be a bug in the
3606 <sect id="exitstatus">
3607 <heading>Exit status</heading>
3610 Each script must return a zero exit status for
3611 success, or a nonzero one for failure, since the package
3612 management system looks for the exit status of these scripts
3613 and determines what action to take next based on that datum.
3617 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3622 <list compact="compact">
3624 <var>new-preinst</var> <tt>install</tt>
3627 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3630 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3633 <var>old-preinst</var> <tt>abort-upgrade</tt>
3634 <var>new-version</var>
3639 <list compact="compact">
3641 <var>postinst</var> <tt>configure</tt>
3642 <var>most-recently-configured-version</var>
3645 <var>old-postinst</var> <tt>abort-upgrade</tt>
3646 <var>new-version</var>
3649 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3650 <tt>in-favour</tt> <var>package</var>
3651 <var>new-version</var>
3654 <var>postinst</var> <tt>abort-remove</tt>
3657 <var>deconfigured's-postinst</var>
3658 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3659 <var>failed-install-package</var> <var>version</var>
3660 [<tt>removing</tt> <var>conflicting-package</var>
3666 <list compact="compact">
3668 <var>prerm</var> <tt>remove</tt>
3671 <var>old-prerm</var> <tt>upgrade</tt>
3672 <var>new-version</var>
3675 <var>new-prerm</var> <tt>failed-upgrade</tt>
3676 <var>old-version</var>
3679 <var>conflictor's-prerm</var> <tt>remove</tt>
3680 <tt>in-favour</tt> <var>package</var>
3681 <var>new-version</var>
3684 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3685 <tt>in-favour</tt> <var>package-being-installed</var>
3686 <var>version</var> [<tt>removing</tt>
3687 <var>conflicting-package</var>
3693 <list compact="compact">
3695 <var>postrm</var> <tt>remove</tt>
3698 <var>postrm</var> <tt>purge</tt>
3701 <var>old-postrm</var> <tt>upgrade</tt>
3702 <var>new-version</var>
3705 <var>new-postrm</var> <tt>failed-upgrade</tt>
3706 <var>old-version</var>
3709 <var>new-postrm</var> <tt>abort-install</tt>
3712 <var>new-postrm</var> <tt>abort-install</tt>
3713 <var>old-version</var>
3716 <var>new-postrm</var> <tt>abort-upgrade</tt>
3717 <var>old-version</var>
3720 <var>disappearer's-postrm</var> <tt>disappear</tt>
3721 <var>overwriter</var>
3722 <var>overwriter-version</var>
3728 <sect id="unpackphase">
3729 <heading>Details of unpack phase of installation or upgrade</heading>
3732 The procedure on installation/upgrade/overwrite/disappear
3733 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3734 stage of <tt>dpkg --install</tt>) is as follows. In each
3735 case, if a major error occurs (unless listed below) the
3736 actions are, in general, run backwards - this means that the
3737 maintainer scripts are run with different arguments in
3738 reverse order. These are the "error unwind" calls listed
3745 If a version of the package is already installed, call
3746 <example compact="compact">
3747 <var>old-prerm</var> upgrade <var>new-version</var>
3751 If the script runs but exits with a non-zero
3752 exit status, <prgn>dpkg</prgn> will attempt:
3753 <example compact="compact">
3754 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3756 If this works, the upgrade continues. If this
3757 does not work, the error unwind:
3758 <example compact="compact">
3759 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3761 If this works, then the old-version is
3762 "Installed", if not, the old version is in a
3763 "Half-Configured" state.
3769 If a "conflicting" package is being removed at the same time,
3770 or if any package will be broken (due to <tt>Breaks</tt>):
3773 If <tt>--auto-deconfigure</tt> is
3774 specified, call, for each package to be deconfigured
3775 due to <tt>Breaks</tt>:
3776 <example compact="compact">
3777 <var>deconfigured's-prerm</var> deconfigure \
3778 in-favour <var>package-being-installed</var> <var>version</var>
3781 <example compact="compact">
3782 <var>deconfigured's-postinst</var> abort-deconfigure \
3783 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3785 The deconfigured packages are marked as
3786 requiring configuration, so that if
3787 <tt>--install</tt> is used they will be
3788 configured again if possible.
3791 If any packages depended on a conflicting
3792 package being removed and <tt>--auto-deconfigure</tt> is
3793 specified, call, for each such package:
3794 <example compact="compact">
3795 <var>deconfigured's-prerm</var> deconfigure \
3796 in-favour <var>package-being-installed</var> <var>version</var> \
3797 removing <var>conflicting-package</var> <var>version</var>
3800 <example compact="compact">
3801 <var>deconfigured's-postinst</var> abort-deconfigure \
3802 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3803 removing <var>conflicting-package</var> <var>version</var>
3805 The deconfigured packages are marked as
3806 requiring configuration, so that if
3807 <tt>--install</tt> is used they will be
3808 configured again if possible.
3811 To prepare for removal of each conflicting package, call:
3812 <example compact="compact">
3813 <var>conflictor's-prerm</var> remove \
3814 in-favour <var>package</var> <var>new-version</var>
3817 <example compact="compact">
3818 <var>conflictor's-postinst</var> abort-remove \
3819 in-favour <var>package</var> <var>new-version</var>
3828 If the package is being upgraded, call:
3829 <example compact="compact">
3830 <var>new-preinst</var> upgrade <var>old-version</var>
3832 If this fails, we call:
3834 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3841 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3843 is called. If this works, then the old version
3844 is in an "Installed" state, or else it is left
3845 in an "Unpacked" state.
3850 If it fails, then the old version is left
3851 in an "Half-Installed" state.
3858 Otherwise, if the package had some configuration
3859 files from a previous version installed (i.e., it
3860 is in the "configuration files only" state):
3861 <example compact="compact">
3862 <var>new-preinst</var> install <var>old-version</var>
3866 <var>new-postrm</var> abort-install <var>old-version</var>
3868 If this fails, the package is left in a
3869 "Half-Installed" state, which requires a
3870 reinstall. If it works, the packages is left in
3871 a "Config-Files" state.
3874 Otherwise (i.e., the package was completely purged):
3875 <example compact="compact">
3876 <var>new-preinst</var> install
3879 <example compact="compact">
3880 <var>new-postrm</var> abort-install
3882 If the error-unwind fails, the package is in a
3883 "Half-Installed" phase, and requires a
3884 reinstall. If the error unwind works, the
3885 package is in a not installed state.
3892 The new package's files are unpacked, overwriting any
3893 that may be on the system already, for example any
3894 from the old version of the same package or from
3895 another package. Backups of the old files are kept
3896 temporarily, and if anything goes wrong the package
3897 management system will attempt to put them back as
3898 part of the error unwind.
3902 It is an error for a package to contain files which
3903 are on the system in another package, unless
3904 <tt>Replaces</tt> is used (see <ref id="replaces">).
3906 The following paragraph is not currently the case:
3907 Currently the <tt>- - force-overwrite</tt> flag is
3908 enabled, downgrading it to a warning, but this may not
3914 It is a more serious error for a package to contain a
3915 plain file or other kind of non-directory where another
3916 package has a directory (again, unless
3917 <tt>Replaces</tt> is used). This error can be
3918 overridden if desired using
3919 <tt>--force-overwrite-dir</tt>, but this is not
3924 Packages which overwrite each other's files produce
3925 behavior which, though deterministic, is hard for the
3926 system administrator to understand. It can easily
3927 lead to "missing" programs if, for example, a package
3928 is installed which overwrites a file from another
3929 package, and is then removed again.<footnote>
3930 Part of the problem is due to what is arguably a
3931 bug in <prgn>dpkg</prgn>.
3936 A directory will never be replaced by a symbolic link
3937 to a directory or vice versa; instead, the existing
3938 state (symlink or not) will be left alone and
3939 <prgn>dpkg</prgn> will follow the symlink if there is
3948 If the package is being upgraded, call
3949 <example compact="compact">
3950 <var>old-postrm</var> upgrade <var>new-version</var>
3954 If this fails, <prgn>dpkg</prgn> will attempt:
3955 <example compact="compact">
3956 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3958 If this works, installation continues. If not,
3960 <example compact="compact">
3961 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3963 If this fails, the old version is left in a
3964 "Half-Installed" state. If it works, dpkg now
3966 <example compact="compact">
3967 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3969 If this fails, the old version is left in a
3970 "Half-Installed" state. If it works, dpkg now
3972 <example compact="compact">
3973 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3975 If this fails, the old version is in an
3982 This is the point of no return - if
3983 <prgn>dpkg</prgn> gets this far, it won't back off
3984 past this point if an error occurs. This will
3985 leave the package in a fairly bad state, which
3986 will require a successful re-installation to clear
3987 up, but it's when <prgn>dpkg</prgn> starts doing
3988 things that are irreversible.
3993 Any files which were in the old version of the package
3994 but not in the new are removed.
3998 The new file list replaces the old.
4002 The new maintainer scripts replace the old.
4006 Any packages all of whose files have been overwritten
4007 during the installation, and which aren't required for
4008 dependencies, are considered to have been removed.
4009 For each such package
4012 <prgn>dpkg</prgn> calls:
4013 <example compact="compact">
4014 <var>disappearer's-postrm</var> disappear \
4015 <var>overwriter</var> <var>overwriter-version</var>
4019 The package's maintainer scripts are removed.
4022 It is noted in the status database as being in a
4023 sane state, namely not installed (any conffiles
4024 it may have are ignored, rather than being
4025 removed by <prgn>dpkg</prgn>). Note that
4026 disappearing packages do not have their prerm
4027 called, because <prgn>dpkg</prgn> doesn't know
4028 in advance that the package is going to
4035 Any files in the package we're unpacking that are also
4036 listed in the file lists of other packages are removed
4037 from those lists. (This will lobotomize the file list
4038 of the "conflicting" package if there is one.)
4042 The backup files made during installation, above, are
4048 The new package's status is now sane, and recorded as
4053 Here is another point of no return - if the
4054 conflicting package's removal fails we do not unwind
4055 the rest of the installation; the conflicting package
4056 is left in a half-removed limbo.
4061 If there was a conflicting package we go and do the
4062 removal actions (described below), starting with the
4063 removal of the conflicting package's files (any that
4064 are also in the package being installed have already
4065 been removed from the conflicting package's file list,
4066 and so do not get removed now).
4072 <sect id="configdetails"><heading>Details of configuration</heading>
4075 When we configure a package (this happens with <tt>dpkg
4076 --install</tt> and <tt>dpkg --configure</tt>), we first
4077 update any <tt>conffile</tt>s and then call:
4078 <example compact="compact">
4079 <var>postinst</var> configure <var>most-recently-configured-version</var>
4084 No attempt is made to unwind after errors during
4085 configuration. If the configuration fails, the package is in
4086 a "Failed Config" state, and an error message is generated.
4090 If there is no most recently configured version
4091 <prgn>dpkg</prgn> will pass a null argument.
4094 Historical note: Truly ancient (pre-1997) versions of
4095 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4096 (including the angle brackets) in this case. Even older
4097 ones did not pass a second argument at all, under any
4098 circumstance. Note that upgrades using such an old dpkg
4099 version are unlikely to work for other reasons, even if
4100 this old argument behavior is handled by your postinst script.
4106 <sect id="removedetails"><heading>Details of removal and/or
4107 configuration purging</heading>
4113 <example compact="compact">
4114 <var>prerm</var> remove
4118 If prerm fails during replacement due to conflict
4120 <var>conflictor's-postinst</var> abort-remove \
4121 in-favour <var>package</var> <var>new-version</var>
4125 <var>postinst</var> abort-remove
4129 If this fails, the package is in a "Half-Configured"
4130 state, or else it remains "Installed".
4134 The package's files are removed (except <tt>conffile</tt>s).
4137 <example compact="compact">
4138 <var>postrm</var> remove
4142 If it fails, there's no error unwind, and the package is in
4143 an "Half-Installed" state.
4148 All the maintainer scripts except the <prgn>postrm</prgn>
4153 If we aren't purging the package we stop here. Note
4154 that packages which have no <prgn>postrm</prgn> and no
4155 <tt>conffile</tt>s are automatically purged when
4156 removed, as there is no difference except for the
4157 <prgn>dpkg</prgn> status.
4161 The <tt>conffile</tt>s and any backup files
4162 (<tt>~</tt>-files, <tt>#*#</tt> files,
4163 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4168 <example compact="compact">
4169 <var>postrm</var> purge
4173 If this fails, the package remains in a "Config-Files"
4178 The package's file list is removed.
4187 <chapt id="relationships">
4188 <heading>Declaring relationships between packages</heading>
4190 <sect id="depsyntax">
4191 <heading>Syntax of relationship fields</heading>
4194 These fields all have a uniform syntax. They are a list of
4195 package names separated by commas.
4199 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4200 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4201 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4202 control file fields of the package, which declare
4203 dependencies on other packages, the package names listed may
4204 also include lists of alternative package names, separated
4205 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4206 if any one of the alternative packages is installed, that
4207 part of the dependency is considered to be satisfied.
4211 All of the fields except for <tt>Provides</tt> may restrict
4212 their applicability to particular versions of each named
4213 package. This is done in parentheses after each individual
4214 package name; the parentheses should contain a relation from
4215 the list below followed by a version number, in the format
4216 described in <ref id="f-Version">.
4220 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4221 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4222 strictly earlier, earlier or equal, exactly equal, later or
4223 equal and strictly later, respectively. The deprecated
4224 forms <tt><</tt> and <tt>></tt> were used to mean
4225 earlier/later or equal, rather than strictly earlier/later,
4226 so they should not appear in new packages (though
4227 <prgn>dpkg</prgn> still supports them).
4231 Whitespace may appear at any point in the version
4232 specification subject to the rules in <ref
4233 id="controlsyntax">, and must appear where it's necessary to
4234 disambiguate; it is not otherwise significant. All of the
4235 relationship fields may span multiple lines. For
4236 consistency and in case of future changes to
4237 <prgn>dpkg</prgn> it is recommended that a single space be
4238 used after a version relationship and before a version
4239 number; it is also conventional to put a single space after
4240 each comma, on either side of each vertical bar, and before
4241 each open parenthesis. When wrapping a relationship field, it
4242 is conventional to do so after a comma and before the space
4243 following that comma.
4247 For example, a list of dependencies might appear as:
4248 <example compact="compact">
4251 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4256 All fields that specify build-time relationships
4257 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4258 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
4259 may be restricted to a certain set of architectures. This
4260 is indicated in brackets after each individual package name and
4261 the optional version specification. The brackets enclose a
4262 list of Debian architecture names separated by whitespace.
4263 Exclamation marks may be prepended to each of the names.
4264 (It is not permitted for some names to be prepended with
4265 exclamation marks while others aren't.) If the current Debian
4266 host architecture is not in this list and there are no
4267 exclamation marks in the list, or it is in the list with a
4268 prepended exclamation mark, the package name and the
4269 associated version specification are ignored completely for
4270 the purposes of defining the relationships.
4275 <example compact="compact">
4277 Build-Depends-Indep: texinfo
4278 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4279 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4281 requires <tt>kernel-headers-2.2.10</tt> on all architectures
4282 other than hurd-i386 and requires <tt>hurd-dev</tt> and
4283 <tt>gnumach-dev</tt> only on hurd-i386.
4287 If the architecture-restricted dependency is part of a set of
4288 alternatives using <tt>|</tt>, that alternative is ignored
4289 completely on architectures that do not match the restriction.
4291 <example compact="compact">
4292 Build-Depends: foo [!i386] | bar [!amd64]
4294 is equivalent to <tt>bar</tt> on the i386 architecture, to
4295 <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
4296 bar</tt> on all other architectures.
4300 All fields that specify build-time relationships may also be
4301 restricted to a certain set of architectures using architecture
4302 wildcards. The syntax for declaring such restrictions is the
4303 same as declaring restrictions using a certain set of
4304 architectures without architecture wildcards. For example:
4305 <example compact="compact">
4306 Build-Depends: foo [linux-any], bar [any-i386], baz [!linux-any]
4308 is equivalent to <tt>foo</tt> on architectures using the Linux
4309 kernel and any cpu, <tt>bar</tt> on architectures using any
4310 kernel and an i386 cpu, and <tt>baz</tt> on any architecture
4311 using a kernel other than Linux.
4315 Note that the binary package relationship fields such as
4316 <tt>Depends</tt> appear in one of the binary package
4317 sections of the control file, whereas the build-time
4318 relationships such as <tt>Build-Depends</tt> appear in the
4319 source package section of the control file (which is the
4324 <sect id="binarydeps">
4325 <heading>Binary Dependencies - <tt>Depends</tt>,
4326 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4327 <tt>Pre-Depends</tt>
4331 Packages can declare in their control file that they have
4332 certain relationships to other packages - for example, that
4333 they may not be installed at the same time as certain other
4334 packages, and/or that they depend on the presence of others.
4338 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4339 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4340 <tt>Breaks</tt> and <tt>Conflicts</tt> control file fields.
4341 <tt>Breaks</tt> is described in <ref id="breaks">, and
4342 <tt>Conflicts</tt> is described in <ref id="conflicts">. The
4343 rest are described below.
4347 These seven fields are used to declare a dependency
4348 relationship by one package on another. Except for
4349 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4350 depending (binary) package's control file.
4351 (<tt>Enhances</tt> appears in the recommending package's
4352 control file, and <tt>Breaks</tt> appears in the version of
4353 depended-on package which causes the named package to
4358 A <tt>Depends</tt> field takes effect <em>only</em> when a
4359 package is to be configured. It does not prevent a package
4360 being on the system in an unconfigured state while its
4361 dependencies are unsatisfied, and it is possible to replace
4362 a package whose dependencies are satisfied and which is
4363 properly installed with a different version whose
4364 dependencies are not and cannot be satisfied; when this is
4365 done the depending package will be left unconfigured (since
4366 attempts to configure it will give errors) and will not
4367 function properly. If it is necessary, a
4368 <tt>Pre-Depends</tt> field can be used, which has a partial
4369 effect even when a package is being unpacked, as explained
4370 in detail below. (The other three dependency fields,
4371 <tt>Recommends</tt>, <tt>Suggests</tt> and
4372 <tt>Enhances</tt>, are only used by the various front-ends
4373 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4374 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4378 For this reason packages in an installation run are usually
4379 all unpacked first and all configured later; this gives
4380 later versions of packages with dependencies on later
4381 versions of other packages the opportunity to have their
4382 dependencies satisfied.
4386 In case of circular dependencies, since installation or
4387 removal order honoring the dependency order can't be
4388 established, dependency loops are broken at some point
4389 (based on rules below), and some packages may not be able to
4390 rely on their dependencies being present when being
4391 installed or removed, depending on which side of the break
4392 of the circular dependency loop they happen to be on. If one
4393 of the packages in the loop has no postinst script, then the
4394 cycle will be broken at that package, so as to ensure that
4395 all postinst scripts run with the dependencies properly
4396 configured if this is possible. Otherwise the breaking point
4401 The <tt>Depends</tt> field thus allows package maintainers
4402 to impose an order in which packages should be configured.
4406 The meaning of the five dependency fields is as follows:
4408 <tag><tt>Depends</tt></tag>
4411 This declares an absolute dependency. A package will
4412 not be configured unless all of the packages listed in
4413 its <tt>Depends</tt> field have been correctly
4418 The <tt>Depends</tt> field should be used if the
4419 depended-on package is required for the depending
4420 package to provide a significant amount of
4425 The <tt>Depends</tt> field should also be used if the
4426 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4427 <prgn>postrm</prgn> scripts require the package to be
4428 present in order to run. Note, however, that the
4429 <prgn>postrm</prgn> cannot rely on any non-essential
4430 packages to be present during the <tt>purge</tt>
4434 <tag><tt>Recommends</tt></tag>
4437 This declares a strong, but not absolute, dependency.
4441 The <tt>Recommends</tt> field should list packages
4442 that would be found together with this one in all but
4443 unusual installations.
4447 <tag><tt>Suggests</tt></tag>
4449 This is used to declare that one package may be more
4450 useful with one or more others. Using this field
4451 tells the packaging system and the user that the
4452 listed packages are related to this one and can
4453 perhaps enhance its usefulness, but that installing
4454 this one without them is perfectly reasonable.
4457 <tag><tt>Enhances</tt></tag>
4459 This field is similar to Suggests but works in the
4460 opposite direction. It is used to declare that a
4461 package can enhance the functionality of another
4465 <tag><tt>Pre-Depends</tt></tag>
4468 This field is like <tt>Depends</tt>, except that it
4469 also forces <prgn>dpkg</prgn> to complete installation
4470 of the packages named before even starting the
4471 installation of the package which declares the
4472 pre-dependency, as follows:
4476 When a package declaring a pre-dependency is about to
4477 be <em>unpacked</em> the pre-dependency can be
4478 satisfied if the depended-on package is either fully
4479 configured, <em>or even if</em> the depended-on
4480 package(s) are only unpacked or in the "Half-Configured"
4481 state, provided that they have been configured
4482 correctly at some point in the past (and not removed
4483 or partially removed since). In this case, both the
4484 previously-configured and currently unpacked or
4485 "Half-Configured" versions must satisfy any version
4486 clause in the <tt>Pre-Depends</tt> field.
4490 When the package declaring a pre-dependency is about
4491 to be <em>configured</em>, the pre-dependency will be
4492 treated as a normal <tt>Depends</tt>, that is, it will
4493 be considered satisfied only if the depended-on
4494 package has been correctly configured.
4498 <tt>Pre-Depends</tt> should be used sparingly,
4499 preferably only by packages whose premature upgrade or
4500 installation would hamper the ability of the system to
4501 continue with any upgrade that might be in progress.
4505 <tt>Pre-Depends</tt> are also required if the
4506 <prgn>preinst</prgn> script depends on the named
4507 package. It is best to avoid this situation if
4515 When selecting which level of dependency to use you should
4516 consider how important the depended-on package is to the
4517 functionality of the one declaring the dependency. Some
4518 packages are composed of components of varying degrees of
4519 importance. Such a package should list using
4520 <tt>Depends</tt> the package(s) which are required by the
4521 more important components. The other components'
4522 requirements may be mentioned as Suggestions or
4523 Recommendations, as appropriate to the components' relative
4529 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4532 When one binary package declares that it breaks another,
4533 <prgn>dpkg</prgn> will refuse to allow the package which
4534 declares <tt>Breaks</tt> be installed unless the broken
4535 package is deconfigured first, and it will refuse to
4536 allow the broken package to be reconfigured.
4540 A package will not be regarded as causing breakage merely
4541 because its configuration files are still installed; it must
4542 be at least "Half-Installed".
4546 A special exception is made for packages which declare that
4547 they break their own package name or a virtual package which
4548 they provide (see below): this does not count as a real
4553 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4554 version clause; such a <tt>Breaks</tt> is introduced in the
4555 version of an (implicit or explicit) dependency which
4556 violates an assumption or reveals a bug in earlier versions
4557 of the broken package. This use of <tt>Breaks</tt> will
4558 inform higher-level package management tools that broken
4559 package must be upgraded before the new one.
4563 If the breaking package also overwrites some files from the
4564 older package, it should use <tt>Replaces</tt> (not
4565 <tt>Conflicts</tt>) to ensure this goes smoothly.
4569 <sect id="conflicts">
4570 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4573 When one binary package declares a conflict with another
4574 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4575 refuse to allow them to be installed on the system at the
4580 If one package is to be installed, the other must be removed
4581 first - if the package being installed is marked as
4582 replacing (see <ref id="replaces">) the one on the system,
4583 or the one on the system is marked as deselected, or both
4584 packages are marked <tt>Essential</tt>, then
4585 <prgn>dpkg</prgn> will automatically remove the package
4586 which is causing the conflict, otherwise it will halt the
4587 installation of the new package with an error. This
4588 mechanism is specifically designed to produce an error when
4589 the installed package is <tt>Essential</tt>, but the new
4594 A package will not cause a conflict merely because its
4595 configuration files are still installed; it must be at least
4600 A special exception is made for packages which declare a
4601 conflict with their own package name, or with a virtual
4602 package which they provide (see below): this does not
4603 prevent their installation, and allows a package to conflict
4604 with others providing a replacement for it. You use this
4605 feature when you want the package in question to be the only
4606 package providing some feature.
4610 A <tt>Conflicts</tt> entry should almost never have an
4611 "earlier than" version clause. This would prevent
4612 <prgn>dpkg</prgn> from upgrading or installing the package
4613 which declared such a conflict until the upgrade or removal
4614 of the conflicted-with package had been completed. Instead,
4615 <tt>Breaks</tt> may be used.
4619 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4623 As well as the names of actual ("concrete") packages, the
4624 package relationship fields <tt>Depends</tt>,
4625 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4626 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4627 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4628 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4629 may mention "virtual packages".
4633 A <em>virtual package</em> is one which appears in the
4634 <tt>Provides</tt> control file field of another package.
4635 The effect is as if the package(s) which provide a
4636 particular virtual package name had been listed by name
4637 everywhere the virtual package name appears. (See also <ref
4642 If there are both concrete and virtual packages of the same
4643 name, then the dependency may be satisfied (or the conflict
4644 caused) by either the concrete package with the name in
4645 question or any other concrete package which provides the
4646 virtual package with the name in question. This is so that,
4647 for example, supposing we have
4648 <example compact="compact">
4651 </example> and someone else releases an enhanced version of
4652 the <tt>bar</tt> package they can say:
4653 <example compact="compact">
4657 and the <tt>bar-plus</tt> package will now also satisfy the
4658 dependency for the <tt>foo</tt> package.
4662 If a relationship field has a version number attached
4663 then only real packages will be considered to see whether
4664 the relationship is satisfied (or the prohibition violated,
4665 for a conflict or breakage) - it is assumed that a real
4666 package which provides the virtual package is not of the
4667 "right" version. So, a <tt>Provides</tt> field may not
4668 contain version numbers, and the version number of the
4669 concrete package which provides a particular virtual package
4670 will not be looked at when considering a dependency on or
4671 conflict with the virtual package name.
4675 It is likely that the ability will be added in a future
4676 release of <prgn>dpkg</prgn> to specify a version number for
4677 each virtual package it provides. This feature is not yet
4678 present, however, and is expected to be used only
4683 If you want to specify which of a set of real packages
4684 should be the default to satisfy a particular dependency on
4685 a virtual package, you should list the real package as an
4686 alternative before the virtual one.
4691 <sect id="replaces"><heading>Overwriting files and replacing
4692 packages - <tt>Replaces</tt></heading>
4695 Packages can declare in their control file that they should
4696 overwrite files in certain other packages, or completely
4697 replace other packages. The <tt>Replaces</tt> control file
4698 field has these two distinct purposes.
4701 <sect1><heading>Overwriting files in other packages</heading>
4704 Firstly, as mentioned before, it is usually an error for a
4705 package to contain files which are on the system in
4710 However, if the overwriting package declares that it
4711 <tt>Replaces</tt> the one containing the file being
4712 overwritten, then <prgn>dpkg</prgn> will replace the file
4713 from the old package with that from the new. The file
4714 will no longer be listed as "owned" by the old package.
4718 If a package is completely replaced in this way, so that
4719 <prgn>dpkg</prgn> does not know of any files it still
4720 contains, it is considered to have "disappeared". It will
4721 be marked as not wanted on the system (selected for
4722 removal) and not installed. Any <tt>conffile</tt>s
4723 details noted for the package will be ignored, as they
4724 will have been taken over by the overwriting package. The
4725 package's <prgn>postrm</prgn> script will be run with a
4726 special argument to allow the package to do any final
4727 cleanup required. See <ref id="mscriptsinstact">.
4730 Replaces is a one way relationship -- you have to
4731 install the replacing package after the replaced
4738 For this usage of <tt>Replaces</tt>, virtual packages (see
4739 <ref id="virtual">) are not considered when looking at a
4740 <tt>Replaces</tt> field - the packages declared as being
4741 replaced must be mentioned by their real names.
4745 Furthermore, this usage of <tt>Replaces</tt> only takes
4746 effect when both packages are at least partially on the
4747 system at once, so that it can only happen if they do not
4748 conflict or if the conflict has been overridden.
4753 <sect1><heading>Replacing whole packages, forcing their
4757 Secondly, <tt>Replaces</tt> allows the packaging system to
4758 resolve which package should be removed when there is a
4759 conflict - see <ref id="conflicts">. This usage only
4760 takes effect when the two packages <em>do</em> conflict,
4761 so that the two usages of this field do not interfere with
4766 In this situation, the package declared as being replaced
4767 can be a virtual package, so for example, all mail
4768 transport agents (MTAs) would have the following fields in
4769 their control files:
4770 <example compact="compact">
4771 Provides: mail-transport-agent
4772 Conflicts: mail-transport-agent
4773 Replaces: mail-transport-agent
4775 ensuring that only one MTA can be installed at any one
4780 <sect id="sourcebinarydeps">
4781 <heading>Relationships between source and binary packages -
4782 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4783 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4787 Source packages that require certain binary packages to be
4788 installed or absent at the time of building the package
4789 can declare relationships to those binary packages.
4793 This is done using the <tt>Build-Depends</tt>,
4794 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4795 <tt>Build-Conflicts-Indep</tt> control file fields.
4799 Build-dependencies on "build-essential" binary packages can be
4800 omitted. Please see <ref id="pkg-relations"> for more information.
4804 The dependencies and conflicts they define must be satisfied
4805 (as defined earlier for binary packages) in order to invoke
4806 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4808 If you make "build-arch" or "binary-arch", you need
4809 Build-Depends. If you make "build-indep" or
4810 "binary-indep", you need Build-Depends and
4811 Build-Depends-Indep. If you make "build" or "binary",
4815 There is no Build-Depends-Arch; this role is essentially
4816 met with Build-Depends. Anyone building the
4817 <tt>build-indep</tt> and binary-indep<tt></tt> targets
4818 is basically assumed to be building the whole package
4819 anyway and so installs all build dependencies. The
4820 autobuilders use <tt>dpkg-buildpackage -B</tt>, which
4821 calls <tt>build</tt> (not <tt>build-arch</tt>, since it
4822 does not yet know how to check for its existence) and
4823 <tt>binary-arch</tt>.
4826 The purpose of the original split, I recall, was so that
4827 the autobuilders wouldn't need to install extra packages
4828 needed only for the binary-indep targets. But without a
4829 build-arch/build-indep split, this didn't work, since
4830 most of the work is done in the build target, not in the
4836 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4838 The <tt>Build-Depends</tt> and
4839 <tt>Build-Conflicts</tt> fields must be satisfied when
4840 any of the following targets is invoked:
4841 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4842 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4843 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4845 <tag><tt>Build-Depends-Indep</tt>,
4846 <tt>Build-Conflicts-Indep</tt></tag>
4848 The <tt>Build-Depends-Indep</tt> and
4849 <tt>Build-Conflicts-Indep</tt> fields must be
4850 satisfied when any of the following targets is
4851 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4852 <tt>binary</tt> and <tt>binary-indep</tt>.
4862 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4865 Packages containing shared libraries must be constructed with
4866 a little care to make sure that the shared library is always
4867 available. This is especially important for packages whose
4868 shared libraries are vitally important, such as the C library
4869 (currently <tt>libc6</tt>).
4873 Packages involving shared libraries should be split up into
4874 several binary packages. This section mostly deals with how
4875 this separation is to be accomplished; rules for files within
4876 the shared library packages are in <ref id="libraries"> instead.
4879 <sect id="sharedlibs-runtime">
4880 <heading>Run-time shared libraries</heading>
4883 The run-time shared library needs to be placed in a package
4884 whose name changes whenever the shared object version
4887 Since it is common place to install several versions of a
4888 package that just provides shared libraries, it is a
4889 good idea that the library package should not
4890 contain any extraneous non-versioned files, unless they
4891 happen to be in versioned directories.</p>
4893 The most common mechanism is to place it in a package
4895 <package><var>libraryname</var><var>soversion</var></package>,
4896 where <file><var>soversion</var></file> is the version number
4897 in the soname of the shared library<footnote>
4898 The soname is the shared object name: it's the thing
4899 that has to match exactly between building an executable
4900 and running it for the dynamic linker to be able run the
4901 program. For example, if the soname of the library is
4902 <file>libfoo.so.6</file>, the library package would be
4903 called <file>libfoo6</file>.
4905 Alternatively, if it would be confusing to directly append
4906 <var>soversion</var> to <var>libraryname</var> (e.g. because
4907 <var>libraryname</var> itself ends in a number), you may use
4908 <package><var>libraryname</var>-<var>soversion</var></package> and
4909 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4914 If you have several shared libraries built from the same
4915 source tree you may lump them all together into a single
4916 shared library package, provided that you change all of
4917 their sonames at once (so that you don't get filename
4918 clashes if you try to install different versions of the
4919 combined shared libraries package).
4923 The package should install the shared libraries under
4924 their normal names. For example, the <package>libgdbm3</package>
4925 package should install <file>libgdbm.so.3.0.0</file> as
4926 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4927 renamed or re-linked by any <prgn>prerm</prgn> or
4928 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4929 of renaming things safely without affecting running programs,
4930 and attempts to interfere with this are likely to lead to
4935 Shared libraries should not be installed executable, since
4936 the dynamic linker does not require this and trying to
4937 execute a shared library usually results in a core dump.
4941 The run-time library package should include the symbolic link that
4942 <prgn>ldconfig</prgn> would create for the shared libraries.
4943 For example, the <package>libgdbm3</package> package should include
4944 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4945 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4946 linker (for example <prgn>ld.so</prgn> or
4947 <prgn>ld-linux.so.*</prgn>) can find the library between the
4948 time that <prgn>dpkg</prgn> installs it and the time that
4949 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4951 The package management system requires the library to be
4952 placed before the symbolic link pointing to it in the
4953 <file>.deb</file> file. This is so that when
4954 <prgn>dpkg</prgn> comes to install the symlink
4955 (overwriting the previous symlink pointing at an older
4956 version of the library), the new shared library is already
4957 in place. In the past, this was achieved by creating the
4958 library in the temporary packaging directory before
4959 creating the symlink. Unfortunately, this was not always
4960 effective, since the building of the tar file in the
4961 <file>.deb</file> depended on the behavior of the underlying
4962 file system. Some file systems (such as reiserfs) reorder
4963 the files so that the order of creation is forgotten.
4964 Since version 1.7.0, <prgn>dpkg</prgn>
4965 reorders the files itself as necessary when building a
4966 package. Thus it is no longer important to concern
4967 oneself with the order of file creation.
4971 <sect1 id="ldconfig">
4972 <heading><tt>ldconfig</tt></heading>
4975 Any package installing shared libraries in one of the default
4976 library directories of the dynamic linker (which are currently
4977 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4978 listed in <file>/etc/ld.so.conf</file><footnote>
4980 <list compact="compact">
4981 <item>/usr/local/lib</item>
4982 <item>/usr/lib/libc5-compat</item>
4983 <item>/lib/libc5-compat</item>
4986 must use <prgn>ldconfig</prgn> to update the shared library
4991 The package maintainer scripts must only call
4992 <prgn>ldconfig</prgn> under these circumstances:
4993 <list compact="compact">
4994 <item>When the <prgn>postinst</prgn> script is run with a
4995 first argument of <tt>configure</tt>, the script must call
4996 <prgn>ldconfig</prgn>, and may optionally invoke
4997 <prgn>ldconfig</prgn> at other times.
4999 <item>When the <prgn>postrm</prgn> script is run with a
5000 first argument of <tt>remove</tt>, the script should call
5001 <prgn>ldconfig</prgn>.
5006 During install or upgrade, the preinst is called before
5007 the new files are installed, so calling "ldconfig" is
5008 pointless. The preinst of an existing package can also be
5009 called if an upgrade fails. However, this happens during
5010 the critical time when a shared libs may exist on-disk
5011 under a temporary name. Thus, it is dangerous and
5012 forbidden by current policy to call "ldconfig" at this
5017 When a package is installed or upgraded, "postinst
5018 configure" runs after the new files are safely on-disk.
5019 Since it is perfectly safe to invoke ldconfig
5020 unconditionally in a postinst, it is OK for a package to
5021 simply put ldconfig in its postinst without checking the
5022 argument. The postinst can also be called to recover from
5023 a failed upgrade. This happens before any new files are
5024 unpacked, so there is no reason to call "ldconfig" at this
5029 For a package that is being removed, prerm is
5030 called with all the files intact, so calling ldconfig is
5031 useless. The other calls to "prerm" happen in the case of
5032 upgrade at a time when all the files of the old package
5033 are on-disk, so again calling "ldconfig" is pointless.
5037 postrm, on the other hand, is called with the "remove"
5038 argument just after the files are removed, so this is
5039 the proper time to call "ldconfig" to notify the system
5040 of the fact that the shared libraries from the package
5041 are removed. The postrm can be called at several other
5042 times. At the time of "postrm purge", "postrm
5043 abort-install", or "postrm abort-upgrade", calling
5044 "ldconfig" is useless because the shared lib files are
5045 not on-disk. However, when "postrm" is invoked with
5046 arguments "upgrade", "failed-upgrade", or "disappear", a
5047 shared lib may exist on-disk under a temporary filename.
5055 <sect id="sharedlibs-support-files">
5056 <heading>Shared library support files</heading>
5059 If your package contains files whose names do not change with
5060 each change in the library shared object version, you must not
5061 put them in the shared library package. Otherwise, several
5062 versions of the shared library cannot be installed at the same
5063 time without filename clashes, making upgrades and transitions
5064 unnecessarily difficult.
5068 It is recommended that supporting files and run-time support
5069 programs that do not need to be invoked manually by users, but
5070 are nevertheless required for the package to function, be placed
5071 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
5072 preferably under <file>/usr/lib/</file><var>package-name</var>.
5073 If the program or file is architecture independent, the
5074 recommendation is for it to be placed in a subdirectory of
5075 <file>/usr/share</file> instead, preferably under
5076 <file>/usr/share/</file><var>package-name</var>. Following the
5077 <var>package-name</var> naming convention ensures that the file
5078 names change when the shared object version changes.
5082 Run-time support programs that use the shared library but are
5083 not required for the library to function or files used by the
5084 shared library that can be used by any version of the shared
5085 library package should instead be put in a separate package.
5086 This package might typically be named
5087 <package><var>libraryname</var>-tools</package>; note the
5088 absence of the <var>soversion</var> in the package name.
5092 Files and support programs only useful when compiling software
5093 against the library should be included in the development
5094 package for the library.<footnote>
5095 For example, a <file><var>package-name</var>-config</file>
5096 script or <package>pkg-config</package> configuration files.
5101 <sect id="sharedlibs-static">
5102 <heading>Static libraries</heading>
5105 The static library (<file><var>libraryname.a</var></file>)
5106 is usually provided in addition to the shared version.
5107 It is placed into the development package (see below).
5111 In some cases, it is acceptable for a library to be
5112 available in static form only; these cases include:
5114 <item>libraries for languages whose shared library support
5115 is immature or unstable</item>
5116 <item>libraries whose interfaces are in flux or under
5117 development (commonly the case when the library's
5118 major version number is zero, or where the ABI breaks
5119 across patchlevels)</item>
5120 <item>libraries which are explicitly intended to be
5121 available only in static form by their upstream
5126 <sect id="sharedlibs-dev">
5127 <heading>Development files</heading>
5130 The development files associated to a shared library need to be
5131 placed in a package called
5132 <package><var>libraryname</var><var>soversion</var>-dev</package>,
5133 or if you prefer only to support one development version at a
5134 time, <package><var>libraryname</var>-dev</package>.
5138 In case several development versions of a library exist, you may
5139 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5140 <ref id="conflicts">) to ensure that the user only installs one
5141 development version at a time (as different development versions are
5142 likely to have the same header files in them, which would cause a
5143 filename clash if both were installed).
5147 The development package should contain a symlink for the associated
5148 shared library without a version number. For example, the
5149 <package>libgdbm-dev</package> package should include a symlink
5150 from <file>/usr/lib/libgdbm.so</file> to
5151 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5152 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5153 <file>libgdbm.so</file> when compiling dynamically.
5157 <sect id="sharedlibs-intradeps">
5158 <heading>Dependencies between the packages of the same library</heading>
5161 Typically the development version should have an exact
5162 version dependency on the runtime library, to make sure that
5163 compilation and linking happens correctly. The
5164 <tt>${binary:Version}</tt> substitution variable can be
5165 useful for this purpose.
5167 Previously, <tt>${Source-Version}</tt> was used, but its name
5168 was confusing and it has been deprecated since dpkg 1.13.19.
5173 <sect id="sharedlibs-shlibdeps">
5174 <heading>Dependencies between the library and other packages -
5175 the <tt>shlibs</tt> system</heading>
5178 If a package contains a binary or library which links to a
5179 shared library, we must ensure that when the package is
5180 installed on the system, all of the libraries needed are
5181 also installed. This requirement led to the creation of the
5182 <tt>shlibs</tt> system, which is very simple in its design:
5183 any package which <em>provides</em> a shared library also
5184 provides information on the package dependencies required to
5185 ensure the presence of this library, and any package which
5186 <em>uses</em> a shared library uses this information to
5187 determine the dependencies it requires. The files which
5188 contain the mapping from shared libraries to the necessary
5189 dependency information are called <file>shlibs</file> files.
5193 Thus, when a package is built which contains any shared
5194 libraries, it must provide a <file>shlibs</file> file for other
5195 packages to use, and when a package is built which contains
5196 any shared libraries or compiled binaries, it must run
5197 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5198 on these to determine the libraries used and hence the
5199 dependencies needed by this package.<footnote>
5201 In the past, the shared libraries linked to were
5202 determined by calling <prgn>ldd</prgn>, but now
5203 <prgn>objdump</prgn> is used to do this. The only
5204 change this makes to package building is that
5205 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
5206 libraries, whereas in the past this was unnecessary.
5207 The rest of this footnote explains the advantage that
5212 We say that a binary <tt>foo</tt> <em>directly</em> uses
5213 a library <tt>libbar</tt> if it is explicitly linked
5214 with that library (that is, it uses the flag
5215 <tt>-lbar</tt> during the linking stage). Other
5216 libraries that are needed by <tt>libbar</tt> are linked
5217 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5218 linker will load them automatically when it loads
5219 <tt>libbar</tt>. A package should depend on
5220 the libraries it directly uses, and the dependencies for
5221 those libraries should automatically pull in the other
5226 Unfortunately, the <prgn>ldd</prgn> program shows both
5227 the directly and indirectly used libraries, meaning that
5228 the dependencies determined included both direct and
5229 indirect dependencies. The use of <prgn>objdump</prgn>
5230 avoids this problem by determining only the directly
5235 A good example of where this helps is the following. We
5236 could update <tt>libimlib</tt> with a new version that
5237 supports a new graphics format called dgf (but retaining
5238 the same major version number). If we used the old
5239 <prgn>ldd</prgn> method, every package that uses
5240 <tt>libimlib</tt> would need to be recompiled so it
5241 would also depend on <tt>libdgf</tt> or it wouldn't run
5242 due to missing symbols. However with the new system,
5243 packages using <tt>libimlib</tt> can rely on
5244 <tt>libimlib</tt> itself having the dependency on
5245 <tt>libdgf</tt> and so they would not need rebuilding.
5251 In the following sections, we will first describe where the
5252 various <tt>shlibs</tt> files are to be found, then how to
5253 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5254 file format and how to create them if your package contains a
5259 <heading>The <tt>shlibs</tt> files present on the system</heading>
5262 There are several places where <tt>shlibs</tt> files are
5263 found. The following list gives them in the order in which
5265 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5266 (The first one which gives the required information is used.)
5272 <p><file>debian/shlibs.local</file></p>
5275 This lists overrides for this package. Its use is
5276 described below (see <ref id="shlibslocal">).
5281 <p><file>/etc/dpkg/shlibs.override</file></p>
5284 This lists global overrides. This list is normally
5285 empty. It is maintained by the local system
5291 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5294 When packages are being built, any
5295 <file>debian/shlibs</file> files are copied into the
5296 control file area of the temporary build directory and
5297 given the name <file>shlibs</file>. These files give
5298 details of any shared libraries included in the
5300 An example may help here. Let us say that the
5301 source package <tt>foo</tt> generates two binary
5302 packages, <tt>libfoo2</tt> and
5303 <tt>foo-runtime</tt>. When building the binary
5304 packages, the two packages are created in the
5305 directories <file>debian/libfoo2</file> and
5306 <file>debian/foo-runtime</file> respectively.
5307 (<file>debian/tmp</file> could be used instead of one
5308 of these.) Since <tt>libfoo2</tt> provides the
5309 <tt>libfoo</tt> shared library, it will require a
5310 <tt>shlibs</tt> file, which will be installed in
5311 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
5313 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
5314 when <prgn>dpkg-shlibdeps</prgn> is run on the
5316 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
5318 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5319 determine whether <tt>foo-prog</tt>'s library
5320 dependencies are satisfied by any of the libraries
5321 provided by <tt>libfoo2</tt>. For this reason,
5322 <prgn>dpkg-shlibdeps</prgn> must only be run once
5323 all of the individual binary packages'
5324 <tt>shlibs</tt> files have been installed into the
5331 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5334 These are the <file>shlibs</file> files corresponding to
5335 all of the packages installed on the system, and are
5336 maintained by the relevant package maintainers.
5341 <p><file>/etc/dpkg/shlibs.default</file></p>
5344 This file lists any shared libraries whose packages
5345 have failed to provide correct <file>shlibs</file> files.
5346 It was used when the <file>shlibs</file> setup was first
5347 introduced, but it is now normally empty. It is
5348 maintained by the <tt>dpkg</tt> maintainer.
5356 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5357 <file>shlibs</file> files</heading>
5361 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5362 into your <file>debian/rules</file> file. If your package
5363 contains only compiled binaries and libraries (but no scripts),
5364 you can use a command such as:
5365 <example compact="compact">
5366 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5367 debian/tmp/usr/lib/*
5369 Otherwise, you will need to explicitly list the compiled
5370 binaries and libraries.<footnote>
5371 If you are using <tt>debhelper</tt>, the
5372 <prgn>dh_shlibdeps</prgn> program will do this work for
5373 you. It will also correctly handle multi-binary
5379 This command puts the dependency information into the
5380 <file>debian/substvars</file> file, which is then used by
5381 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5382 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5383 field in the control file for this to work.
5387 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
5388 done. If it does complain you might need to create your own
5389 <file>debian/shlibs.local</file> file, as explained below (see
5390 <ref id="shlibslocal">).
5394 If you have multiple binary packages, you will need to call
5395 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5396 compiled libraries or binaries. In such a case, you will
5397 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5398 utilities to specify a different <file>substvars</file> file.
5402 If you are creating a udeb for use in the Debian Installer,
5403 you will need to specify that <prgn>dpkg-shlibdeps</prgn>
5404 should use the dependency line of type <tt>udeb</tt> by
5405 adding the <tt>-tudeb</tt> option<footnote>
5406 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5407 will automatically add this option if it knows it is
5409 </footnote>. If there is no dependency line of type <tt>udeb</tt>
5410 in the <file>shlibs</file> file, <prgn>dpkg-shlibdeps</prgn> will
5411 fall back to the regular dependency line.
5415 For more details on dpkg-shlibdeps, please see
5416 <ref id="pkg-dpkg-shlibdeps"> and
5417 <manref name="dpkg-shlibdeps" section="1">.
5422 <heading>The <file>shlibs</file> File Format</heading>
5425 Each <file>shlibs</file> file has the same format. Lines
5426 beginning with <tt>#</tt> are considered to be comments and
5427 are ignored. Each line is of the form:
5428 <example compact="compact">
5429 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5434 We will explain this by reference to the example of the
5435 <tt>zlib1g</tt> package, which (at the time of writing)
5436 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5440 <var>type</var> is an optional element that indicates the type
5441 of package for which the line is valid. The only type currently
5442 in use is <tt>udeb</tt>. The colon and space after the type are
5447 <var>library-name</var> is the name of the shared library,
5448 in this case <tt>libz</tt>. (This must match the name part
5449 of the soname, see below.)
5453 <var>soname-version</var> is the version part of the soname of
5454 the library. The soname is the thing that must exactly match
5455 for the library to be recognized by the dynamic linker, and is
5457 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5458 example, <tt>libz.so.1</tt>.<footnote>
5459 This can be determined using the command
5460 <example compact="compact">
5461 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5464 The version part is the part which comes after
5465 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
5469 <var>dependencies</var> has the same syntax as a dependency
5470 field in a binary package control file. It should give
5471 details of which packages are required to satisfy a binary
5472 built against the version of the library contained in the
5473 package. See <ref id="depsyntax"> for details.
5477 In our example, if the first version of the <tt>zlib1g</tt>
5478 package which contained a minor number of at least
5479 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5480 <tt>shlibs</tt> entry for this library could say:
5481 <example compact="compact">
5482 libz 1 zlib1g (>= 1:1.1.3)
5484 The version-specific dependency is to avoid warnings from
5485 the dynamic linker about using older shared libraries with
5490 As zlib1g also provides a udeb containing the shared library,
5491 there would also be a second line:
5492 <example compact="compact">
5493 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5499 <heading>Providing a <file>shlibs</file> file</heading>
5502 If your package provides a shared library, you need to create
5503 a <file>shlibs</file> file following the format described above.
5504 It is usual to call this file <file>debian/shlibs</file> (but if
5505 you have multiple binary packages, you might want to call it
5506 <file>debian/shlibs.<var>package</var></file> instead). Then
5507 let <file>debian/rules</file> install it in the control area:
5508 <example compact="compact">
5509 install -m644 debian/shlibs debian/tmp/DEBIAN
5511 or, in the case of a multi-binary package:
5512 <example compact="compact">
5513 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5515 An alternative way of doing this is to create the
5516 <file>shlibs</file> file in the control area directly from
5517 <file>debian/rules</file> without using a <file>debian/shlibs</file>
5518 file at all,<footnote>
5519 This is what <prgn>dh_makeshlibs</prgn> in the
5520 <tt>debhelper</tt> suite does. If your package also has a udeb
5521 that provides a shared library, <prgn>dh_makeshlibs</prgn> can
5522 automatically generate the <tt>udeb:</tt> lines if you specify
5523 the name of the udeb with the <tt>--add-udeb</tt> option.
5525 since the <file>debian/shlibs</file> file itself is ignored by
5526 <prgn>dpkg-shlibdeps</prgn>.
5530 As <prgn>dpkg-shlibdeps</prgn> reads the
5531 <file>DEBIAN/shlibs</file> files in all of the binary packages
5532 being built from this source package, all of the
5533 <file>DEBIAN/shlibs</file> files should be installed before
5534 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5539 <sect1 id="shlibslocal">
5540 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
5543 This file is intended only as a <em>temporary</em> fix if
5544 your binaries or libraries depend on a library whose package
5545 does not yet provide a correct <file>shlibs</file> file.
5549 We will assume that you are trying to package a binary
5550 <tt>foo</tt>. When you try running
5551 <prgn>dpkg-shlibdeps</prgn> you get the following error
5552 message (<tt>-O</tt> displays the dependency information on
5553 <tt>stdout</tt> instead of writing it to
5554 <tt>debian/substvars</tt>, and the lines have been wrapped
5555 for ease of reading):
5556 <example compact="compact">
5557 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
5558 dpkg-shlibdeps: warning: unable to find dependency
5559 information for shared library libbar (soname 1,
5560 path /usr/lib/libbar.so.1, dependency field Depends)
5561 shlibs:Depends=libc6 (>= 2.2.2-2)
5563 You can then run <prgn>ldd</prgn> on the binary to find the
5564 full location of the library concerned:
5565 <example compact="compact">
5567 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5568 libc.so.6 => /lib/libc.so.6 (0x40032000)
5569 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5571 So the <prgn>foo</prgn> binary depends on the
5572 <prgn>libbar</prgn> shared library, but no package seems to
5573 provide a <file>*.shlibs</file> file handling
5574 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5575 determine the package responsible:
5576 <example compact="compact">
5577 $ dpkg -S /usr/lib/libbar.so.1
5578 bar1: /usr/lib/libbar.so.1
5579 $ dpkg -s bar1 | grep Version
5582 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5583 is the one we are using. Now we can file a bug against the
5584 <tt>bar1</tt> package and create our own
5585 <file>debian/shlibs.local</file> to locally fix the problem.
5586 Including the following line into your
5587 <file>debian/shlibs.local</file> file:
5588 <example compact="compact">
5589 libbar 1 bar1 (>= 1.0-1)
5591 should allow the package build to work.
5595 As soon as the maintainer of <tt>bar1</tt> provides a
5596 correct <file>shlibs</file> file, you should remove this line
5597 from your <file>debian/shlibs.local</file> file. (You should
5598 probably also then have a versioned <tt>Build-Depends</tt>
5599 on <tt>bar1</tt> to help ensure that others do not have the
5600 same problem building your package.)
5609 <chapt id="opersys"><heading>The Operating System</heading>
5612 <heading>File system hierarchy</heading>
5616 <heading>File System Structure</heading>
5619 The location of all installed files and directories must
5620 comply with the Filesystem Hierarchy Standard (FHS),
5621 version 2.3, with the exceptions noted below, and except
5622 where doing so would violate other terms of Debian
5623 Policy. The following exceptions to the FHS apply:
5628 The optional rules related to user specific
5629 configuration files for applications are stored in
5630 the user's home directory are relaxed. It is
5631 recommended that such files start with the
5632 '<tt>.</tt>' character (a "dot file"), and if an
5633 application needs to create more than one dot file
5634 then the preferred placement is in a subdirectory
5635 with a name starting with a '.' character, (a "dot
5636 directory"). In this case it is recommended the
5637 configuration files not start with the '.'
5643 The requirement for amd64 to use <file>/lib64</file>
5644 for 64 bit binaries is removed.
5649 The requirement for object files, internal binaries, and
5650 libraries, including <file>libc.so.*</file>, to be located
5651 directly under <file>/lib{,32}</file> and
5652 <file>/usr/lib{,32}</file> is amended, permitting files
5653 to instead be installed to
5654 <file>/lib/<var>triplet</var></file> and
5655 <file>/usr/lib/<var>triplet</var></file>, where
5656 <tt><var>triplet</var></tt> is the value returned by
5657 <tt>dpkg-architecture -qDEB_HOST_GNU_TYPE</tt> for the
5658 architecture of the package. Packages may <em>not</em>
5659 install files to any <var>triplet</var> path other
5660 than the one matching the architecture of that package;
5661 for instance, an <tt>Architecture: amd64</tt> package
5662 containing 32-bit x86 libraries may not install these
5663 libraries to <file>/usr/lib/i486-linux-gnu</file>.
5665 This is necessary in order to reserve the directories for
5666 use in cross-installation of library packages from other
5667 architectures, as part of the planned deployment of
5672 Applications may also use a single subdirectory under
5673 <file>/usr/lib/<var>triplet</var></file>.
5676 The execution time linker/loader, ld*, must still be made
5677 available in the existing location under /lib or /lib64
5678 since this is part of the ELF ABI for the architecture.
5683 The requirement that
5684 <file>/usr/local/share/man</file> be "synonymous"
5685 with <file>/usr/local/man</file> is relaxed to a
5690 The requirement that windowmanagers with a single
5691 configuration file call it <file>system.*wmrc</file>
5692 is removed, as is the restriction that the window
5693 manager subdirectory be named identically to the
5694 window manager name itself.
5699 The requirement that boot manager configuration
5700 files live in <file>/etc</file>, or at least are
5701 symlinked there, is relaxed to a recommendation.
5706 The following directories in the root filesystem are
5707 additionally allowed: <file>/sys</file> and
5708 <file>/selinux</file>. <footnote>These directories
5709 are used as mount points to mount virtual filesystems
5710 to get access to kernel information.</footnote>
5717 The version of this document referred here can be
5718 found in the <tt>debian-policy</tt> package or on <url
5719 id="http://www.debian.org/doc/packaging-manuals/fhs/"
5720 name="FHS (Debian copy)"> alongside this manual (or, if
5721 you have the <package>debian-policy</package> installed,
5723 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5724 (local copy)">). The
5725 latest version, which may be a more recent version, may
5727 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5728 Specific questions about following the standard may be
5729 asked on the <tt>debian-devel</tt> mailing list, or
5730 referred to the FHS mailing list (see the
5731 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5737 <heading>Site-specific programs</heading>
5740 As mandated by the FHS, packages must not place any
5741 files in <file>/usr/local</file>, either by putting them in
5742 the file system archive to be unpacked by <prgn>dpkg</prgn>
5743 or by manipulating them in their maintainer scripts.
5747 However, the package may create empty directories below
5748 <file>/usr/local</file> so that the system administrator knows
5749 where to place site-specific files. These are not
5750 directories <em>in</em> <file>/usr/local</file>, but are
5751 children of directories in <file>/usr/local</file>. These
5752 directories (<file>/usr/local/*/dir/</file>)
5753 should be removed on package removal if they are
5758 Note that this applies only to
5759 directories <em>below</em> <file>/usr/local</file>,
5760 not <em>in</em> <file>/usr/local</file>. Packages must
5761 not create sub-directories in the
5762 directory <file>/usr/local</file> itself, except those
5763 listed in FHS, section 4.5. However, you may create
5764 directories below them as you wish. You must not remove
5765 any of the directories listed in 4.5, even if you created
5770 Since <file>/usr/local</file> can be mounted read-only from a
5771 remote server, these directories must be created and
5772 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5773 maintainer scripts and not be included in the
5774 <file>.deb</file> archive. These scripts must not fail if
5775 either of these operations fail.
5779 For example, the <tt>emacsen-common</tt> package could
5780 contain something like
5781 <example compact="compact">
5782 if [ ! -e /usr/local/share/emacs ]
5784 if mkdir /usr/local/share/emacs 2>/dev/null
5786 chown root:staff /usr/local/share/emacs
5787 chmod 2775 /usr/local/share/emacs
5791 in its <prgn>postinst</prgn> script, and
5792 <example compact="compact">
5793 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5794 rmdir /usr/local/share/emacs 2>/dev/null || true
5796 in the <prgn>prerm</prgn> script. (Note that this form is
5797 used to ensure that if the script is interrupted, the
5798 directory <file>/usr/local/share/emacs</file> will still be
5803 If you do create a directory in <file>/usr/local</file> for
5804 local additions to a package, you should ensure that
5805 settings in <file>/usr/local</file> take precedence over the
5806 equivalents in <file>/usr</file>.
5810 However, because <file>/usr/local</file> and its contents are
5811 for exclusive use of the local administrator, a package
5812 must not rely on the presence or absence of files or
5813 directories in <file>/usr/local</file> for normal operation.
5817 The <file>/usr/local</file> directory itself and all the
5818 subdirectories created by the package should (by default) have
5819 permissions 2775 (group-writable and set-group-id) and be
5820 owned by <tt>root:staff</tt>.
5825 <heading>The system-wide mail directory</heading>
5827 The system-wide mail directory
5828 is <file>/var/mail</file>. This directory is part of the
5829 base system and should not be owned by any particular mail
5830 agents. The use of the old
5831 location <file>/var/spool/mail</file> is deprecated, even
5832 though the spool may still be physically located there.
5838 <heading>Users and groups</heading>
5841 <heading>Introduction</heading>
5843 The Debian system can be configured to use either plain or
5848 Some user ids (UIDs) and group ids (GIDs) are reserved
5849 globally for use by certain packages. Because some
5850 packages need to include files which are owned by these
5851 users or groups, or need the ids compiled into binaries,
5852 these ids must be used on any Debian system only for the
5853 purpose for which they are allocated. This is a serious
5854 restriction, and we should avoid getting in the way of
5855 local administration policies. In particular, many sites
5856 allocate users and/or local system groups starting at 100.
5860 Apart from this we should have dynamically allocated ids,
5861 which should by default be arranged in some sensible
5862 order, but the behavior should be configurable.
5866 Packages other than <tt>base-passwd</tt> must not modify
5867 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5868 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5873 <heading>UID and GID classes</heading>
5875 The UID and GID numbers are divided into classes as
5881 Globally allocated by the Debian project, the same
5882 on every Debian system. These ids will appear in
5883 the <file>passwd</file> and <file>group</file> files of all
5884 Debian systems, new ids in this range being added
5885 automatically as the <tt>base-passwd</tt> package is
5890 Packages which need a single statically allocated
5891 uid or gid should use one of these; their
5892 maintainers should ask the <tt>base-passwd</tt>
5900 Dynamically allocated system users and groups.
5901 Packages which need a user or group, but can have
5902 this user or group allocated dynamically and
5903 differently on each system, should use <tt>adduser
5904 --system</tt> to create the group and/or user.
5905 <prgn>adduser</prgn> will check for the existence of
5906 the user or group, and if necessary choose an unused
5907 id based on the ranges specified in
5908 <file>adduser.conf</file>.
5912 <tag>1000-59999:</tag>
5915 Dynamically allocated user accounts. By default
5916 <prgn>adduser</prgn> will choose UIDs and GIDs for
5917 user accounts in this range, though
5918 <file>adduser.conf</file> may be used to modify this
5923 <tag>60000-64999:</tag>
5926 Globally allocated by the Debian project, but only
5927 created on demand. The ids are allocated centrally
5928 and statically, but the actual accounts are only
5929 created on users' systems on demand.
5933 These ids are for packages which are obscure or
5934 which require many statically-allocated ids. These
5935 packages should check for and create the accounts in
5936 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5937 <prgn>adduser</prgn> if it has this facility) if
5938 necessary. Packages which are likely to require
5939 further allocations should have a "hole" left after
5940 them in the allocation, to give them room to
5945 <tag>65000-65533:</tag>
5953 User <tt>nobody</tt>. The corresponding gid refers
5954 to the group <tt>nogroup</tt>.
5961 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5962 not</em> be used, because it is the error return
5971 <sect id="sysvinit">
5972 <heading>System run levels and <file>init.d</file> scripts</heading>
5974 <sect1 id="/etc/init.d">
5975 <heading>Introduction</heading>
5978 The <file>/etc/init.d</file> directory contains the scripts
5979 executed by <prgn>init</prgn> at boot time and when the
5980 init state (or "runlevel") is changed (see <manref
5981 name="init" section="8">).
5985 There are at least two different, yet functionally
5986 equivalent, ways of handling these scripts. For the sake
5987 of simplicity, this document describes only the symbolic
5988 link method. However, it must not be assumed by maintainer
5989 scripts that this method is being used, and any automated
5990 manipulation of the various runlevel behaviors by
5991 maintainer scripts must be performed using
5992 <prgn>update-rc.d</prgn> as described below and not by
5993 manually installing or removing symlinks. For information
5994 on the implementation details of the other method,
5995 implemented in the <tt>file-rc</tt> package, please refer
5996 to the documentation of that package.
6000 These scripts are referenced by symbolic links in the
6001 <file>/etc/rc<var>n</var>.d</file> directories. When changing
6002 runlevels, <prgn>init</prgn> looks in the directory
6003 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
6004 execute, where <tt><var>n</var></tt> is the runlevel that
6005 is being changed to, or <tt>S</tt> for the boot-up
6010 The names of the links all have the form
6011 <file>S<var>mm</var><var>script</var></file> or
6012 <file>K<var>mm</var><var>script</var></file> where
6013 <var>mm</var> is a two-digit number and <var>script</var>
6014 is the name of the script (this should be the same as the
6015 name of the actual script in <file>/etc/init.d</file>).
6019 When <prgn>init</prgn> changes runlevel first the targets
6020 of the links whose names start with a <tt>K</tt> are
6021 executed, each with the single argument <tt>stop</tt>,
6022 followed by the scripts prefixed with an <tt>S</tt>, each
6023 with the single argument <tt>start</tt>. (The links are
6024 those in the <file>/etc/rc<var>n</var>.d</file> directory
6025 corresponding to the new runlevel.) The <tt>K</tt> links
6026 are responsible for killing services and the <tt>S</tt>
6027 link for starting services upon entering the runlevel.
6031 For example, if we are changing from runlevel 2 to
6032 runlevel 3, init will first execute all of the <tt>K</tt>
6033 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
6034 all of the <tt>S</tt> prefixed scripts in that directory.
6035 The links starting with <tt>K</tt> will cause the
6036 referred-to file to be executed with an argument of
6037 <tt>stop</tt>, and the <tt>S</tt> links with an argument
6042 The two-digit number <var>mm</var> is used to determine
6043 the order in which to run the scripts: low-numbered links
6044 have their scripts run first. For example, the
6045 <tt>K20</tt> scripts will be executed before the
6046 <tt>K30</tt> scripts. This is used when a certain service
6047 must be started before another. For example, the name
6048 server <prgn>bind</prgn> might need to be started before
6049 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
6050 can set up its access lists. In this case, the script
6051 that starts <prgn>bind</prgn> would have a lower number
6052 than the script that starts <prgn>inn</prgn> so that it
6054 <example compact="compact">
6061 The two runlevels 0 (halt) and 6 (reboot) are slightly
6062 different. In these runlevels, the links with an
6063 <tt>S</tt> prefix are still called after those with a
6064 <tt>K</tt> prefix, but they too are called with the single
6065 argument <tt>stop</tt>.
6069 <sect1 id="writing-init">
6070 <heading>Writing the scripts</heading>
6073 Packages that include daemons for system services should
6074 place scripts in <file>/etc/init.d</file> to start or stop
6075 services at boot time or during a change of runlevel.
6076 These scripts should be named
6077 <file>/etc/init.d/<var>package</var></file>, and they should
6078 accept one argument, saying what to do:
6081 <tag><tt>start</tt></tag>
6082 <item>start the service,</item>
6084 <tag><tt>stop</tt></tag>
6085 <item>stop the service,</item>
6087 <tag><tt>restart</tt></tag>
6088 <item>stop and restart the service if it's already running,
6089 otherwise start the service</item>
6091 <tag><tt>reload</tt></tag>
6092 <item><p>cause the configuration of the service to be
6093 reloaded without actually stopping and restarting
6096 <tag><tt>force-reload</tt></tag>
6097 <item>cause the configuration to be reloaded if the
6098 service supports this, otherwise restart the
6102 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
6103 <tt>force-reload</tt> options should be supported by all
6104 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
6109 The <file>init.d</file> scripts must ensure that they will
6110 behave sensibly (i.e., returning success and not starting
6111 multiple copies of a service) if invoked with <tt>start</tt>
6112 when the service is already running, or with <tt>stop</tt>
6113 when it isn't, and that they don't kill unfortunately-named
6114 user processes. The best way to achieve this is usually to
6115 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
6120 Be careful of using <tt>set -e</tt> in <file>init.d</file>
6121 scripts. Writing correct <file>init.d</file> scripts requires
6122 accepting various error exit statuses when daemons are already
6123 running or already stopped without aborting
6124 the <file>init.d</file> script, and common <file>init.d</file>
6125 function libraries are not safe to call with <tt>set -e</tt>
6127 <tt>/lib/lsb/init-functions</tt>, which assists in writing
6128 LSB-compliant init scripts, may fail if <tt>set -e</tt> is
6129 in effect and echoing status messages to the console fails,
6131 </footnote>. For <tt>init.d</tt> scripts, it's often easier
6132 to not use <tt>set -e</tt> and instead check the result of
6133 each command separately.
6137 If a service reloads its configuration automatically (as
6138 in the case of <prgn>cron</prgn>, for example), the
6139 <tt>reload</tt> option of the <file>init.d</file> script
6140 should behave as if the configuration has been reloaded
6145 The <file>/etc/init.d</file> scripts must be treated as
6146 configuration files, either (if they are present in the
6147 package, that is, in the .deb file) by marking them as
6148 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
6149 by managing them correctly in the maintainer scripts (see
6150 <ref id="config-files">). This is important since we want
6151 to give the local system administrator the chance to adapt
6152 the scripts to the local system, e.g., to disable a
6153 service without de-installing the package, or to specify
6154 some special command line options when starting a service,
6155 while making sure their changes aren't lost during the next
6160 These scripts should not fail obscurely when the
6161 configuration files remain but the package has been
6162 removed, as configuration files remain on the system after
6163 the package has been removed. Only when <prgn>dpkg</prgn>
6164 is executed with the <tt>--purge</tt> option will
6165 configuration files be removed. In particular, as the
6166 <file>/etc/init.d/<var>package</var></file> script itself is
6167 usually a <tt>conffile</tt>, it will remain on the system
6168 if the package is removed but not purged. Therefore, you
6169 should include a <tt>test</tt> statement at the top of the
6171 <example compact="compact">
6172 test -f <var>program-executed-later-in-script</var> || exit 0
6177 Often there are some variables in the <file>init.d</file>
6178 scripts whose values control the behavior of the scripts,
6179 and which a system administrator is likely to want to
6180 change. As the scripts themselves are frequently
6181 <tt>conffile</tt>s, modifying them requires that the
6182 administrator merge in their changes each time the package
6183 is upgraded and the <tt>conffile</tt> changes. To ease
6184 the burden on the system administrator, such configurable
6185 values should not be placed directly in the script.
6186 Instead, they should be placed in a file in
6187 <file>/etc/default</file>, which typically will have the same
6188 base name as the <file>init.d</file> script. This extra file
6189 should be sourced by the script when the script runs. It
6190 must contain only variable settings and comments in SUSv3
6191 <prgn>sh</prgn> format. It may either be a
6192 <tt>conffile</tt> or a configuration file maintained by
6193 the package maintainer scripts. See <ref id="config-files">
6198 To ensure that vital configurable values are always
6199 available, the <file>init.d</file> script should set default
6200 values for each of the shell variables it uses, either
6201 before sourcing the <file>/etc/default/</file> file or
6202 afterwards using something like the <tt>:
6203 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6204 script must behave sensibly and not fail if the
6205 <file>/etc/default</file> file is deleted.
6209 <file>/var/run</file> and <file>/var/lock</file> may be mounted
6210 as temporary filesystems<footnote>
6211 For example, using the <tt>RAMRUN</tt> and <tt>RAMLOCK</tt>
6212 options in <file>/etc/default/rcS</file>.
6213 </footnote>, so the <file>init.d</file> scripts must handle this
6214 correctly. This will typically amount to creating any required
6215 subdirectories dynamically when the <file>init.d</file> script
6216 is run, rather than including them in the package and relying on
6217 <prgn>dpkg</prgn> to create them.
6222 <heading>Interfacing with the initscript system</heading>
6225 Maintainers should use the abstraction layer provided by
6226 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6227 programs to deal with initscripts in their packages'
6228 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6229 and <prgn>postrm</prgn>.
6233 Directly managing the /etc/rc?.d links and directly
6234 invoking the <file>/etc/init.d/</file> initscripts should
6235 be done only by packages providing the initscript
6236 subsystem (such as <prgn>sysv-rc</prgn> and
6237 <prgn>file-rc</prgn>).
6241 <heading>Managing the links</heading>
6244 The program <prgn>update-rc.d</prgn> is provided for
6245 package maintainers to arrange for the proper creation and
6246 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6247 or their functional equivalent if another method is being
6248 used. This may be used by maintainers in their packages'
6249 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6253 You must not include any <file>/etc/rc<var>n</var>.d</file>
6254 symbolic links in the actual archive or manually create or
6255 remove the symbolic links in maintainer scripts; you must
6256 use the <prgn>update-rc.d</prgn> program instead. (The
6257 former will fail if an alternative method of maintaining
6258 runlevel information is being used.) You must not include
6259 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6260 in the archive either. (Only the <tt>sysvinit</tt>
6265 By default <prgn>update-rc.d</prgn> will start services in
6266 each of the multi-user state runlevels (2, 3, 4, and 5)
6267 and stop them in the halt runlevel (0), the single-user
6268 runlevel (1) and the reboot runlevel (6). The system
6269 administrator will have the opportunity to customize
6270 runlevels by simply adding, moving, or removing the
6271 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6272 symbolic links are being used, or by modifying
6273 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6278 To get the default behavior for your package, put in your
6279 <prgn>postinst</prgn> script
6280 <example compact="compact">
6281 update-rc.d <var>package</var> defaults
6283 and in your <prgn>postrm</prgn>
6284 <example compact="compact">
6285 if [ "$1" = purge ]; then
6286 update-rc.d <var>package</var> remove
6288 </example>. Note that if your package changes runlevels
6289 or priority, you may have to remove and recreate the links,
6290 since otherwise the old links may persist. Refer to the
6291 documentation of <prgn>update-rc.d</prgn>.
6295 This will use a default sequence number of 20. If it does
6296 not matter when or in which order the <file>init.d</file>
6297 script is run, use this default. If it does, then you
6298 should talk to the maintainer of the <prgn>sysvinit</prgn>
6299 package or post to <tt>debian-devel</tt>, and they will
6300 help you choose a number.
6304 For more information about using <tt>update-rc.d</tt>,
6305 please consult its man page <manref name="update-rc.d"
6311 <heading>Running initscripts</heading>
6313 The program <prgn>invoke-rc.d</prgn> is provided to make
6314 it easier for package maintainers to properly invoke an
6315 initscript, obeying runlevel and other locally-defined
6316 constraints that might limit a package's right to start,
6317 stop and otherwise manage services. This program may be
6318 used by maintainers in their packages' scripts.
6322 The package maintainer scripts must use
6323 <prgn>invoke-rc.d</prgn> to invoke the
6324 <file>/etc/init.d/*</file> initscripts, instead of
6325 calling them directly.
6329 By default, <prgn>invoke-rc.d</prgn> will pass any
6330 action requests (start, stop, reload, restart...) to the
6331 <file>/etc/init.d</file> script, filtering out requests
6332 to start or restart a service out of its intended
6337 Most packages will simply need to change:
6338 <example compact="compact">/etc/init.d/<package>
6339 <action></example> in their <prgn>postinst</prgn>
6340 and <prgn>prerm</prgn> scripts to:
6341 <example compact="compact">
6342 if which invoke-rc.d >/dev/null 2>&1; then
6343 invoke-rc.d <var>package</var> <action>
6345 /etc/init.d/<var>package</var> <action>
6351 A package should register its initscript services using
6352 <prgn>update-rc.d</prgn> before it tries to invoke them
6353 using <prgn>invoke-rc.d</prgn>. Invocation of
6354 unregistered services may fail.
6358 For more information about using
6359 <prgn>invoke-rc.d</prgn>, please consult its man page
6360 <manref name="invoke-rc.d" section="8">.
6366 <heading>Boot-time initialization</heading>
6369 There used to be another directory, <file>/etc/rc.boot</file>,
6370 which contained scripts which were run once per machine
6371 boot. This has been deprecated in favour of links from
6372 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6373 described in <ref id="/etc/init.d">. Packages must not
6374 place files in <file>/etc/rc.boot</file>.
6379 <heading>Example</heading>
6382 An example on which you can base your
6383 <file>/etc/init.d</file> scripts is found in
6384 <file>/etc/init.d/skeleton</file>.
6391 <heading>Console messages from <file>init.d</file> scripts</heading>
6394 This section describes the formats to be used for messages
6395 written to standard output by the <file>/etc/init.d</file>
6396 scripts. The intent is to improve the consistency of
6397 Debian's startup and shutdown look and feel. For this
6398 reason, please look very carefully at the details. We want
6399 the messages to have the same format in terms of wording,
6400 spaces, punctuation and case of letters.
6404 Here is a list of overall rules that should be used for
6405 messages generated by <file>/etc/init.d</file> scripts.
6411 The message should fit in one line (fewer than 80
6412 characters), start with a capital letter and end with
6413 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6417 If the script is performing some time consuming task in
6418 the background (not merely starting or stopping a
6419 program, for instance), an ellipsis (three dots:
6420 <tt>...</tt>) should be output to the screen, with no
6421 leading or tailing whitespace or line feeds.
6425 The messages should appear as if the computer is telling
6426 the user what it is doing (politely :-), but should not
6427 mention "it" directly. For example, instead of:
6428 <example compact="compact">
6429 I'm starting network daemons: nfsd mountd.
6431 the message should say
6432 <example compact="compact">
6433 Starting network daemons: nfsd mountd.
6440 <tt>init.d</tt> script should use the following standard
6441 message formats for the situations enumerated below.
6447 <p>When daemons are started</p>
6450 If the script starts one or more daemons, the output
6451 should look like this (a single line, no leading
6453 <example compact="compact">
6454 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6456 The <var>description</var> should describe the
6457 subsystem the daemon or set of daemons are part of,
6458 while <var>daemon-1</var> up to <var>daemon-n</var>
6459 denote each daemon's name (typically the file name of
6464 For example, the output of <file>/etc/init.d/lpd</file>
6466 <example compact="compact">
6467 Starting printer spooler: lpd.
6472 This can be achieved by saying
6473 <example compact="compact">
6474 echo -n "Starting printer spooler: lpd"
6475 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6478 in the script. If there are more than one daemon to
6479 start, the output should look like this:
6480 <example compact="compact">
6481 echo -n "Starting remote file system services:"
6482 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6483 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6484 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6487 This makes it possible for the user to see what is
6488 happening and when the final daemon has been started.
6489 Care should be taken in the placement of white spaces:
6490 in the example above the system administrators can
6491 easily comment out a line if they don't want to start
6492 a specific daemon, while the displayed message still
6498 <p>When a system parameter is being set</p>
6501 If you have to set up different system parameters
6502 during the system boot, you should use this format:
6503 <example compact="compact">
6504 Setting <var>parameter</var> to "<var>value</var>".
6509 You can use a statement such as the following to get
6511 <example compact="compact">
6512 echo "Setting DNS domainname to \"$domainname\"."
6517 Note that the same symbol (<tt>"</tt>) <!-- " --> is used
6518 for the left and right quotation marks. A grave accent
6519 (<tt>`</tt>) is not a quote character; neither is an
6520 apostrophe (<tt>'</tt>).
6525 <p>When a daemon is stopped or restarted</p>
6528 When you stop or restart a daemon, you should issue a
6529 message identical to the startup message, except that
6530 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6531 or <tt>Restarting</tt> respectively.
6535 For example, stopping the printer daemon will look like
6537 <example compact="compact">
6538 Stopping printer spooler: lpd.
6544 <p>When something is executed</p>
6547 There are several examples where you have to run a
6548 program at system startup or shutdown to perform a
6549 specific task, for example, setting the system's clock
6550 using <prgn>netdate</prgn> or killing all processes
6551 when the system shuts down. Your message should look
6553 <example compact="compact">
6554 Doing something very useful...done.
6556 You should print the <tt>done.</tt> immediately after
6557 the job has been completed, so that the user is
6558 informed why they have to wait. You can get this
6560 <example compact="compact">
6561 echo -n "Doing something very useful..."
6570 <p>When the configuration is reloaded</p>
6573 When a daemon is forced to reload its configuration
6574 files you should use the following format:
6575 <example compact="compact">
6576 Reloading <var>description</var> configuration...done.
6578 where <var>description</var> is the same as in the
6579 daemon starting message.
6587 <heading>Cron jobs</heading>
6590 Packages must not modify the configuration file
6591 <file>/etc/crontab</file>, and they must not modify the files in
6592 <file>/var/spool/cron/crontabs</file>.</p>
6595 If a package wants to install a job that has to be executed
6596 via cron, it should place a file with the name of the
6597 package in one or more of the following directories:
6598 <example compact="compact">
6604 As these directory names imply, the files within them are
6605 executed on an hourly, daily, weekly, or monthly basis,
6606 respectively. The exact times are listed in
6607 <file>/etc/crontab</file>.</p>
6610 All files installed in any of these directories must be
6611 scripts (e.g., shell scripts or Perl scripts) so that they
6612 can easily be modified by the local system administrator.
6613 In addition, they must be treated as configuration files.
6617 If a certain job has to be executed at some other frequency or
6618 at a specific time, the package should install a file
6619 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6620 same syntax as <file>/etc/crontab</file> and is processed by
6621 <prgn>cron</prgn> automatically. The file must also be
6622 treated as a configuration file. (Note that entries in the
6623 <file>/etc/cron.d</file> directory are not handled by
6624 <prgn>anacron</prgn>. Thus, you should only use this
6625 directory for jobs which may be skipped if the system is not
6628 Unlike <file>crontab</file> files described in the IEEE Std
6629 1003.1-2008 (POSIX.1) available from
6630 <url id="http://www.opengroup.org/onlinepubs/9699919799/"
6631 name="The Open Group">, the files in
6632 <file>/etc/cron.d</file> and the file
6633 <file>/etc/crontab</file> have seven fields; namely:
6635 <item>Minute [0,59]</item>
6636 <item>Hour [0,23]</item>
6637 <item>Day of the month [1,31]</item>
6638 <item>Month of the year [1,12]</item>
6639 <item>Day of the week ([0,6] with 0=Sunday)</item>
6640 <item>Username</item>
6641 <item>Command to be run</item>
6643 Ranges of numbers are allowed. Ranges are two numbers
6644 separated with a hyphen. The specified range is inclusive.
6645 Lists are allowed. A list is a set of numbers (or ranges)
6646 separated by commas. Step values can be used in conjunction
6651 The scripts or <tt>crontab</tt> entries in these directories should
6652 check if all necessary programs are installed before they
6653 try to execute them. Otherwise, problems will arise when a
6654 package was removed but not purged since configuration files
6655 are kept on the system in this situation.
6659 Any <tt>cron</tt> daemon must provide
6660 <file>/usr/bin/crontab</file> and support normal
6661 <tt>crontab</tt> entries as specified in POSIX. The daemon
6662 must also support names for days and months, ranges, and
6663 step values. It has to support <file>/etc/crontab</file>,
6664 and correctly execute the scripts in
6665 <file>/etc/cron.d</file>. The daemon must also correctly
6667 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>.
6672 <heading>Menus</heading>
6675 The Debian <tt>menu</tt> package provides a standard
6676 interface between packages providing applications and
6677 <em>menu programs</em> (either X window managers or
6678 text-based menu programs such as <prgn>pdmenu</prgn>).
6682 All packages that provide applications that need not be
6683 passed any special command line arguments for normal
6684 operation should register a menu entry for those
6685 applications, so that users of the <tt>menu</tt> package
6686 will automatically get menu entries in their window
6687 managers, as well in shells like <tt>pdmenu</tt>.
6691 Menu entries should follow the current menu policy.
6695 The menu policy can be found in the <tt>menu-policy</tt>
6696 files in the <tt>debian-policy</tt> package.
6697 It is also available from the Debian web mirrors at
6698 <tt><url name="/doc/packaging-manuals/menu-policy/"
6699 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6703 Please also refer to the <em>Debian Menu System</em>
6704 documentation that comes with the <package>menu</package>
6705 package for information about how to register your
6711 <heading>Multimedia handlers</heading>
6714 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6715 is a mechanism for encoding files and data streams and
6716 providing meta-information about them, in particular their
6717 type (e.g. audio or video) and format (e.g. PNG, HTML,
6722 Registration of MIME type handlers allows programs like mail
6723 user agents and web browsers to invoke these handlers to
6724 view, edit or display MIME types they don't support directly.
6728 Packages which provide the ability to view/show/play,
6729 compose, edit or print MIME types should register themselves
6730 as such following the current MIME support policy.
6734 The MIME support policy can be found in the <tt>mime-policy</tt>
6735 files in the <tt>debian-policy</tt> package.
6736 It is also available from the Debian web mirrors at
6737 <tt><url name="/doc/packaging-manuals/mime-policy/"
6738 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6744 <heading>Keyboard configuration</heading>
6747 To achieve a consistent keyboard configuration so that all
6748 applications interpret a keyboard event the same way, all
6749 programs in the Debian distribution must be configured to
6750 comply with the following guidelines.
6754 The following keys must have the specified interpretations:
6757 <tag><tt><--</tt></tag>
6758 <item>delete the character to the left of the cursor</item>
6760 <tag><tt>Delete</tt></tag>
6761 <item>delete the character to the right of the cursor</item>
6763 <tag><tt>Control+H</tt></tag>
6764 <item>emacs: the help prefix</item>
6767 The interpretation of any keyboard events should be
6768 independent of the terminal that is used, be it a virtual
6769 console, an X terminal emulator, an rlogin/telnet session,
6774 The following list explains how the different programs
6775 should be set up to achieve this:
6781 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6785 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6789 X translations are set up to make
6790 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6791 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6792 is the vt220 escape code for the "delete character"
6793 key). This must be done by loading the X resources
6794 using <prgn>xrdb</prgn> on all local X displays, not
6795 using the application defaults, so that the
6796 translation resources used correspond to the
6797 <prgn>xmodmap</prgn> settings.
6801 The Linux console is configured to make
6802 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6803 generate <tt>ESC [ 3 ~</tt>.
6807 X applications are configured so that <tt><</tt>
6808 deletes left, and <tt>Delete</tt> deletes right. Motif
6809 applications already work like this.
6813 Terminals should have <tt>stty erase ^?</tt> .
6817 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6818 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6819 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6823 Emacs is programmed to map <tt>KB_Backspace</tt> or
6824 the <tt>stty erase</tt> character to
6825 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6826 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6827 <tt>^H</tt> to <tt>help</tt> as always.
6831 Other applications use the <tt>stty erase</tt>
6832 character and <tt>kdch1</tt> for the two delete keys,
6833 with ASCII DEL being "delete previous character" and
6834 <tt>kdch1</tt> being "delete character under
6842 This will solve the problem except for the following
6849 Some terminals have a <tt><--</tt> key that cannot
6850 be made to produce anything except <tt>^H</tt>. On
6851 these terminals Emacs help will be unavailable on
6852 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6853 character takes precedence in Emacs, and has been set
6854 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6855 available) can be used instead.
6859 Some operating systems use <tt>^H</tt> for <tt>stty
6860 erase</tt>. However, modern telnet versions and all
6861 rlogin versions propagate <tt>stty</tt> settings, and
6862 almost all UNIX versions honour <tt>stty erase</tt>.
6863 Where the <tt>stty</tt> settings are not propagated
6864 correctly, things can be made to work by using
6865 <tt>stty</tt> manually.
6869 Some systems (including previous Debian versions) use
6870 <prgn>xmodmap</prgn> to arrange for both
6871 <tt><--</tt> and <tt>Delete</tt> to generate
6872 <tt>KB_Delete</tt>. We can change the behavior of
6873 their X clients using the same X resources that we use
6874 to do it for our own clients, or configure our clients
6875 using their resources when things are the other way
6876 around. On displays configured like this
6877 <tt>Delete</tt> will not work, but <tt><--</tt>
6882 Some operating systems have different <tt>kdch1</tt>
6883 settings in their <tt>terminfo</tt> database for
6884 <tt>xterm</tt> and others. On these systems the
6885 <tt>Delete</tt> key will not work correctly when you
6886 log in from a system conforming to our policy, but
6887 <tt><--</tt> will.
6894 <heading>Environment variables</heading>
6897 A program must not depend on environment variables to get
6898 reasonable defaults. (That's because these environment
6899 variables would have to be set in a system-wide
6900 configuration file like <file>/etc/profile</file>, which is not
6901 supported by all shells.)
6905 If a program usually depends on environment variables for its
6906 configuration, the program should be changed to fall back to
6907 a reasonable default configuration if these environment
6908 variables are not present. If this cannot be done easily
6909 (e.g., if the source code of a non-free program is not
6910 available), the program must be replaced by a small
6911 "wrapper" shell script which sets the environment variables
6912 if they are not already defined, and calls the original program.
6916 Here is an example of a wrapper script for this purpose:
6918 <example compact="compact">
6920 BAR=${BAR:-/var/lib/fubar}
6922 exec /usr/lib/foo/foo "$@"
6927 Furthermore, as <file>/etc/profile</file> is a configuration
6928 file of the <prgn>base-files</prgn> package, other packages must
6929 not put any environment variables or other commands into that
6934 <sect id="doc-base">
6935 <heading>Registering Documents using doc-base</heading>
6938 The <package>doc-base</package> package implements a
6939 flexible mechanism for handling and presenting
6940 documentation. The recommended practice is for every Debian
6941 package that provides online documentation (other than just
6942 manual pages) to register these documents with
6943 <package>doc-base</package> by installing a
6944 <package>doc-base</package> control file via the
6945 <prgn/install-docs/ script at installation time and
6946 de-register the manuals again when the package is removed.
6949 Please refer to the documentation that comes with the
6950 <package>doc-base</package> package for information and
6959 <heading>Files</heading>
6962 <heading>Binaries</heading>
6965 Two different packages must not install programs with
6966 different functionality but with the same filenames. (The
6967 case of two programs having the same functionality but
6968 different implementations is handled via "alternatives" or
6969 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6970 <ref id="conflicts"> respectively.) If this case happens,
6971 one of the programs must be renamed. The maintainers should
6972 report this to the <tt>debian-devel</tt> mailing list and
6973 try to find a consensus about which program will have to be
6974 renamed. If a consensus cannot be reached, <em>both</em>
6975 programs must be renamed.
6979 By default, when a package is being built, any binaries
6980 created should include debugging information, as well as
6981 being compiled with optimization. You should also turn on
6982 as many reasonable compilation warnings as possible; this
6983 makes life easier for porters, who can then look at build
6984 logs for possible problems. For the C programming language,
6985 this means the following compilation parameters should be
6987 <example compact="compact">
6989 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6991 INSTALL = install -s # (or use strip on the files in debian/tmp)
6996 Note that by default all installed binaries should be stripped,
6997 either by using the <tt>-s</tt> flag to
6998 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6999 the binaries after they have been copied into
7000 <file>debian/tmp</file> but before the tree is made into a
7005 Although binaries in the build tree should be compiled with
7006 debugging information by default, it can often be difficult to
7007 debug programs if they are also subjected to compiler
7008 optimization. For this reason, it is recommended to support the
7009 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
7010 (see <ref id="debianrules-options">). This variable can contain
7011 several flags to change how a package is compiled and built.
7015 It is up to the package maintainer to decide what
7016 compilation options are best for the package. Certain
7017 binaries (such as computationally-intensive programs) will
7018 function better with certain flags (<tt>-O3</tt>, for
7019 example); feel free to use them. Please use good judgment
7020 here. Don't use flags for the sake of it; only use them
7021 if there is good reason to do so. Feel free to override
7022 the upstream author's ideas about which compilation
7023 options are best: they are often inappropriate for our
7029 <sect id="libraries">
7030 <heading>Libraries</heading>
7033 If the package is <strong>architecture: any</strong>, then
7034 the shared library compilation and linking flags must have
7035 <tt>-fPIC</tt>, or the package shall not build on some of
7036 the supported architectures<footnote>
7038 If you are using GCC, <tt>-fPIC</tt> produces code with
7039 relocatable position independent code, which is required for
7040 most architectures to create a shared library, with i386 and
7041 perhaps some others where non position independent code is
7042 permitted in a shared library.
7045 Position independent code may have a performance penalty,
7046 especially on <tt>i386</tt>. However, in most cases the
7047 speed penalty must be measured against the memory wasted on
7048 the few architectures where non position independent code is
7051 </footnote>. Any exception to this rule must be discussed on
7052 the mailing list <em>debian-devel@lists.debian.org</em>, and
7053 a rough consensus obtained. The reasons for not compiling
7054 with <tt>-fPIC</tt> flag must be recorded in the file
7055 <tt>README.Debian</tt>, and care must be taken to either
7056 restrict the architecture or arrange for <tt>-fPIC</tt> to
7057 be used on architectures where it is required.<footnote>
7059 Some of the reasons why this might be required is if the
7060 library contains hand crafted assembly code that is not
7061 relocatable, the speed penalty is excessive for compute
7062 intensive libs, and similar reasons.
7067 As to the static libraries, the common case is not to have
7068 relocatable code, since there is no benefit, unless in specific
7069 cases; therefore the static version must not be compiled
7070 with the <tt>-fPIC</tt> flag. Any exception to this rule
7071 should be discussed on the mailing list
7072 <em>debian-devel@lists.debian.org</em>, and the reasons for
7073 compiling with the <tt>-fPIC</tt> flag must be recorded in
7074 the file <tt>README.Debian</tt>. <footnote>
7076 Some of the reasons for linking static libraries with
7077 the <tt>-fPIC</tt> flag are if, for example, one needs a
7078 Perl API for a library that is under rapid development,
7079 and has an unstable API, so shared libraries are
7080 pointless at this phase of the library's development. In
7081 that case, since Perl needs a library with relocatable
7082 code, it may make sense to create a static library with
7083 relocatable code. Another reason cited is if you are
7084 distilling various libraries into a common shared
7085 library, like <tt>mklibs</tt> does in the Debian
7091 In other words, if both a shared and a static library is
7092 being built, each source unit (<tt>*.c</tt>, for example,
7093 for C files) will need to be compiled twice, for the normal
7097 You must specify the gcc option <tt>-D_REENTRANT</tt>
7098 when building a library (either static or shared) to make
7099 the library compatible with LinuxThreads.
7103 Although not enforced by the build tools, shared libraries
7104 must be linked against all libraries that they use symbols from
7105 in the same way that binaries are. This ensures the correct
7106 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
7107 system and guarantees that all libraries can be safely opened
7108 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
7109 option <tt>-Wl,-z,defs</tt> when building a shared library.
7110 Since this option enforces symbol resolution at build time,
7111 a missing library reference will be caught early as a fatal
7116 All installed shared libraries should be stripped with
7117 <example compact="compact">
7118 strip --strip-unneeded <var>your-lib</var>
7120 (The option <tt>--strip-unneeded</tt> makes
7121 <prgn>strip</prgn> remove only the symbols which aren't
7122 needed for relocation processing.) Shared libraries can
7123 function perfectly well when stripped, since the symbols for
7124 dynamic linking are in a separate part of the ELF object
7126 You might also want to use the options
7127 <tt>--remove-section=.comment</tt> and
7128 <tt>--remove-section=.note</tt> on both shared libraries
7129 and executables, and <tt>--strip-debug</tt> on static
7135 Note that under some circumstances it may be useful to
7136 install a shared library unstripped, for example when
7137 building a separate package to support debugging.
7141 Shared object files (often <file>.so</file> files) that are not
7142 public libraries, that is, they are not meant to be linked
7143 to by third party executables (binaries of other packages),
7144 should be installed in subdirectories of the
7145 <file>/usr/lib</file> directory. Such files are exempt from the
7146 rules that govern ordinary shared libraries, except that
7147 they must not be installed executable and should be
7149 A common example are the so-called "plug-ins",
7150 internal shared objects that are dynamically loaded by
7151 programs using <manref name="dlopen" section="3">.
7156 An ever increasing number of packages are using
7157 <prgn>libtool</prgn> to do their linking. The latest GNU
7158 libtools (>= 1.3a) can take advantage of the metadata in the
7159 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
7160 files). The main advantage of <prgn>libtool</prgn>'s
7161 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
7162 store and subsequently access metadata with respect to the
7163 libraries it builds. <prgn>libtool</prgn> will search for
7164 those files, which contain a lot of useful information about
7165 a library (such as library dependency information for static
7166 linking). Also, they're <em>essential</em> for programs
7167 using <tt>libltdl</tt>.<footnote>
7168 Although <prgn>libtool</prgn> is fully capable of
7169 linking against shared libraries which don't have
7170 <tt>.la</tt> files, as it is a mere shell script it can
7171 add considerably to the build time of a
7172 <prgn>libtool</prgn>-using package if that shell script
7173 has to derive all this information from first principles
7174 for each library every time it is linked. With the
7175 advent of <prgn>libtool</prgn> version 1.4 (and to a
7176 lesser extent <prgn>libtool</prgn> version 1.3), the
7177 <file>.la</file> files also store information about
7178 inter-library dependencies which cannot necessarily be
7179 derived after the <file>.la</file> file is deleted.
7184 Packages that use <prgn>libtool</prgn> to create shared
7185 libraries should include the <file>.la</file> files in the
7186 <tt>-dev</tt> package, unless the package relies on
7187 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
7188 the <tt>.la</tt> files must go in the run-time library
7193 You must make sure that you use only released versions of
7194 shared libraries to build your packages; otherwise other
7195 users will not be able to run your binaries
7196 properly. Producing source packages that depend on
7197 unreleased compilers is also usually a bad
7204 <heading>Shared libraries</heading>
7206 This section has moved to <ref id="sharedlibs">.
7212 <heading>Scripts</heading>
7215 All command scripts, including the package maintainer
7216 scripts inside the package and used by <prgn>dpkg</prgn>,
7217 should have a <tt>#!</tt> line naming the shell to be used
7222 In the case of Perl scripts this should be
7223 <tt>#!/usr/bin/perl</tt>.
7227 When scripts are installed into a directory in the system
7228 PATH, the script name should not include an extension such
7229 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7230 language currently used to implement it.
7233 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>) other than
7234 <file>init.d</file> scripts should almost certainly start
7235 with <tt>set -e</tt> so that errors are detected.
7236 <file>init.d</file> scripts are something of a special case, due
7237 to how frequently they need to call commands that are allowed to
7238 fail, and it may instead be easier to check the exit status of
7239 commands directly. See <ref id="writing-init"> for more
7240 information about writing <file>init.d</file> scripts.
7243 Every script should use <tt>set -e</tt> or check the exit status
7244 of <em>every</em> command.
7247 Scripts may assume that <file>/bin/sh</file> implements the
7248 SUSv3 Shell Command Language<footnote>
7249 Single UNIX Specification, version 3, which is also IEEE
7250 1003.1-2004 (POSIX), and is available on the World Wide Web
7251 from <url id="http://www.unix.org/version3/online.html"
7252 name="The Open Group"> after free
7253 registration.</footnote>
7254 plus the following additional features not mandated by
7256 These features are in widespread use in the Linux community
7257 and are implemented in all of bash, dash, and ksh, the most
7258 common shells users may wish to use as <file>/bin/sh</file>.
7261 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7262 must not generate a newline.</item>
7263 <item><tt>test</tt>, if implemented as a shell built-in, must
7264 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7266 <item><tt>local</tt> to create a scoped variable must be
7267 supported, including listing multiple variables in a single
7268 local command and assigning a value to a variable at the
7269 same time as localizing it. <tt>local</tt> may or
7270 may not preserve the variable value from an outer scope if
7271 no assignment is present. Uses such as:
7275 # ... use a, b, c, d ...
7278 must be supported and must set the value of <tt>c</tt> to
7282 If a shell script requires non-SUSv3 features from the shell
7283 interpreter other than those listed above, the appropriate shell
7284 must be specified in the first line of the script (e.g.,
7285 <tt>#!/bin/bash</tt>) and the package must depend on the package
7286 providing the shell (unless the shell package is marked
7287 "Essential", as in the case of <prgn>bash</prgn>).
7291 You may wish to restrict your script to SUSv3 features plus the
7292 above set when possible so that it may use <file>/bin/sh</file>
7293 as its interpreter. If your script works with <prgn>dash</prgn>
7294 (originally called <prgn>ash</prgn>), it probably complies with
7295 the above requirements, but if you are in doubt, use
7296 <file>/bin/bash</file>.
7300 Perl scripts should check for errors when making any
7301 system calls, including <tt>open</tt>, <tt>print</tt>,
7302 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7306 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7307 scripting languages. See <em>Csh Programming Considered
7308 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7309 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7310 If an upstream package comes with <prgn>csh</prgn> scripts
7311 then you must make sure that they start with
7312 <tt>#!/bin/csh</tt> and make your package depend on the
7313 <prgn>c-shell</prgn> virtual package.
7317 Any scripts which create files in world-writeable
7318 directories (e.g., in <file>/tmp</file>) must use a
7319 mechanism which will fail atomically if a file with the same
7320 name already exists.
7324 The Debian base system provides the <prgn>tempfile</prgn>
7325 and <prgn>mktemp</prgn> utilities for use by scripts for
7332 <heading>Symbolic links</heading>
7335 In general, symbolic links within a top-level directory
7336 should be relative, and symbolic links pointing from one
7337 top-level directory into another should be absolute. (A
7338 top-level directory is a sub-directory of the root
7339 directory <file>/</file>.)
7343 In addition, symbolic links should be specified as short as
7344 possible, i.e., link targets like <file>foo/../bar</file> are
7349 Note that when creating a relative link using
7350 <prgn>ln</prgn> it is not necessary for the target of the
7351 link to exist relative to the working directory you're
7352 running <prgn>ln</prgn> from, nor is it necessary to change
7353 directory to the directory where the link is to be made.
7354 Simply include the string that should appear as the target
7355 of the link (this will be a pathname relative to the
7356 directory in which the link resides) as the first argument
7361 For example, in your <prgn>Makefile</prgn> or
7362 <file>debian/rules</file>, you can do things like:
7363 <example compact="compact">
7364 ln -fs gcc $(prefix)/bin/cc
7365 ln -fs gcc debian/tmp/usr/bin/cc
7366 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7367 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7372 A symbolic link pointing to a compressed file should always
7373 have the same file extension as the referenced file. (For
7374 example, if a file <file>foo.gz</file> is referenced by a
7375 symbolic link, the filename of the link has to end with
7376 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7381 <heading>Device files</heading>
7384 Packages must not include device files or named pipes in the
7389 If a package needs any special device files that are not
7390 included in the base system, it must call
7391 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7392 after notifying the user<footnote>
7393 This notification could be done via a (low-priority)
7394 debconf message, or an echo (printf) statement.
7399 Packages must not remove any device files in the
7400 <prgn>postrm</prgn> or any other script. This is left to the
7401 system administrator.
7405 Debian uses the serial devices
7406 <file>/dev/ttyS*</file>. Programs using the old
7407 <file>/dev/cu*</file> devices should be changed to use
7408 <file>/dev/ttyS*</file>.
7412 Named pipes needed by the package must be created in
7413 the <prgn>postinst</prgn> script<footnote>
7414 It's better to use <prgn>mkfifo</prgn> rather
7415 than <prgn>mknod</prgn> to create named pipes so that
7416 automated checks for packages incorrectly creating device
7417 files with <prgn>mknod</prgn> won't have false positives.
7418 </footnote> and removed in
7419 the <prgn>prerm</prgn> or <prgn>postrm</prgn> script as
7424 <sect id="config-files">
7425 <heading>Configuration files</heading>
7428 <heading>Definitions</heading>
7432 <tag>configuration file</tag>
7434 A file that affects the operation of a program, or
7435 provides site- or host-specific information, or
7436 otherwise customizes the behavior of a program.
7437 Typically, configuration files are intended to be
7438 modified by the system administrator (if needed or
7439 desired) to conform to local policy or to provide
7440 more useful site-specific behavior.
7443 <tag><tt>conffile</tt></tag>
7445 A file listed in a package's <tt>conffiles</tt>
7446 file, and is treated specially by <prgn>dpkg</prgn>
7447 (see <ref id="configdetails">).
7453 The distinction between these two is important; they are
7454 not interchangeable concepts. Almost all
7455 <tt>conffile</tt>s are configuration files, but many
7456 configuration files are not <tt>conffiles</tt>.
7460 As noted elsewhere, <file>/etc/init.d</file> scripts,
7461 <file>/etc/default</file> files, scripts installed in
7462 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7463 configuration installed in <file>/etc/cron.d</file> must be
7464 treated as configuration files. In general, any script that
7465 embeds configuration information is de-facto a configuration
7466 file and should be treated as such.
7471 <heading>Location</heading>
7474 Any configuration files created or used by your package
7475 must reside in <file>/etc</file>. If there are several,
7476 consider creating a subdirectory of <file>/etc</file>
7477 named after your package.
7481 If your package creates or uses configuration files
7482 outside of <file>/etc</file>, and it is not feasible to modify
7483 the package to use <file>/etc</file> directly, put the files
7484 in <file>/etc</file> and create symbolic links to those files
7485 from the location that the package requires.
7490 <heading>Behavior</heading>
7493 Configuration file handling must conform to the following
7495 <list compact="compact">
7497 local changes must be preserved during a package
7501 configuration files must be preserved when the
7502 package is removed, and only deleted when the
7509 The easy way to achieve this behavior is to make the
7510 configuration file a <tt>conffile</tt>. This is
7511 appropriate only if it is possible to distribute a default
7512 version that will work for most installations, although
7513 some system administrators may choose to modify it. This
7514 implies that the default version will be part of the
7515 package distribution, and must not be modified by the
7516 maintainer scripts during installation (or at any other
7521 In order to ensure that local changes are preserved
7522 correctly, no package may contain or make hard links to
7523 conffiles.<footnote>
7524 Rationale: There are two problems with hard links.
7525 The first is that some editors break the link while
7526 editing one of the files, so that the two files may
7527 unwittingly become unlinked and different. The second
7528 is that <prgn>dpkg</prgn> might break the hard link
7529 while upgrading <tt>conffile</tt>s.
7534 The other way to do it is via the maintainer scripts. In
7535 this case, the configuration file must not be listed as a
7536 <tt>conffile</tt> and must not be part of the package
7537 distribution. If the existence of a file is required for
7538 the package to be sensibly configured it is the
7539 responsibility of the package maintainer to provide
7540 maintainer scripts which correctly create, update and
7541 maintain the file and remove it on purge. (See <ref
7542 id="maintainerscripts"> for more information.) These
7543 scripts must be idempotent (i.e., must work correctly if
7544 <prgn>dpkg</prgn> needs to re-run them due to errors
7545 during installation or removal), must cope with all the
7546 variety of ways <prgn>dpkg</prgn> can call maintainer
7547 scripts, must not overwrite or otherwise mangle the user's
7548 configuration without asking, must not ask unnecessary
7549 questions (particularly during upgrades), and must
7550 otherwise be good citizens.
7554 The scripts are not required to configure every possible
7555 option for the package, but only those necessary to get
7556 the package running on a given system. Ideally the
7557 sysadmin should not have to do any configuration other
7558 than that done (semi-)automatically by the
7559 <prgn>postinst</prgn> script.
7563 A common practice is to create a script called
7564 <file><var>package</var>-configure</file> and have the
7565 package's <prgn>postinst</prgn> call it if and only if the
7566 configuration file does not already exist. In certain
7567 cases it is useful for there to be an example or template
7568 file which the maintainer scripts use. Such files should
7569 be in <file>/usr/share/<var>package</var></file> or
7570 <file>/usr/lib/<var>package</var></file> (depending on whether
7571 they are architecture-independent or not). There should
7572 be symbolic links to them from
7573 <file>/usr/share/doc/<var>package</var>/examples</file> if
7574 they are examples, and should be perfectly ordinary
7575 <prgn>dpkg</prgn>-handled files (<em>not</em>
7576 configuration files).
7580 These two styles of configuration file handling must
7581 not be mixed, for that way lies madness:
7582 <prgn>dpkg</prgn> will ask about overwriting the file
7583 every time the package is upgraded.
7588 <heading>Sharing configuration files</heading>
7591 Packages which specify the same file as a
7592 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7593 with each other. (This is an instance of the general rule
7594 about not sharing files. Note that neither alternatives
7595 nor diversions are likely to be appropriate in this case;
7596 in particular, <prgn>dpkg</prgn> does not handle diverted
7597 <tt>conffile</tt>s well.)
7601 The maintainer scripts must not alter a <tt>conffile</tt>
7602 of <em>any</em> package, including the one the scripts
7607 If two or more packages use the same configuration file
7608 and it is reasonable for both to be installed at the same
7609 time, one of these packages must be defined as
7610 <em>owner</em> of the configuration file, i.e., it will be
7611 the package which handles that file as a configuration
7612 file. Other packages that use the configuration file must
7613 depend on the owning package if they require the
7614 configuration file to operate. If the other package will
7615 use the configuration file if present, but is capable of
7616 operating without it, no dependency need be declared.
7620 If it is desirable for two or more related packages to
7621 share a configuration file <em>and</em> for all of the
7622 related packages to be able to modify that configuration
7623 file, then the following should be done:
7624 <enumlist compact="compact">
7626 One of the related packages (the "owning" package)
7627 will manage the configuration file with maintainer
7628 scripts as described in the previous section.
7631 The owning package should also provide a program
7632 that the other packages may use to modify the
7636 The related packages must use the provided program
7637 to make any desired modifications to the
7638 configuration file. They should either depend on
7639 the core package to guarantee that the configuration
7640 modifier program is available or accept gracefully
7641 that they cannot modify the configuration file if it
7642 is not. (This is in addition to the fact that the
7643 configuration file may not even be present in the
7650 Sometimes it's appropriate to create a new package which
7651 provides the basic infrastructure for the other packages
7652 and which manages the shared configuration files. (The
7653 <tt>sgml-base</tt> package is a good example.)
7658 <heading>User configuration files ("dotfiles")</heading>
7661 The files in <file>/etc/skel</file> will automatically be
7662 copied into new user accounts by <prgn>adduser</prgn>.
7663 No other program should reference the files in
7664 <file>/etc/skel</file>.
7668 Therefore, if a program needs a dotfile to exist in
7669 advance in <file>$HOME</file> to work sensibly, that dotfile
7670 should be installed in <file>/etc/skel</file> and treated as a
7675 However, programs that require dotfiles in order to
7676 operate sensibly are a bad thing, unless they do create
7677 the dotfiles themselves automatically.
7681 Furthermore, programs should be configured by the Debian
7682 default installation to behave as closely to the upstream
7683 default behavior as possible.
7687 Therefore, if a program in a Debian package needs to be
7688 configured in some way in order to operate sensibly, that
7689 should be done using a site-wide configuration file placed
7690 in <file>/etc</file>. Only if the program doesn't support a
7691 site-wide default configuration and the package maintainer
7692 doesn't have time to add it may a default per-user file be
7693 placed in <file>/etc/skel</file>.
7697 <file>/etc/skel</file> should be as empty as we can make it.
7698 This is particularly true because there is no easy (or
7699 necessarily desirable) mechanism for ensuring that the
7700 appropriate dotfiles are copied into the accounts of
7701 existing users when a package is installed.
7707 <heading>Log files</heading>
7709 Log files should usually be named
7710 <file>/var/log/<var>package</var>.log</file>. If you have many
7711 log files, or need a separate directory for permission
7712 reasons (<file>/var/log</file> is writable only by
7713 <file>root</file>), you should usually create a directory named
7714 <file>/var/log/<var>package</var></file> and place your log
7719 Log files must be rotated occasionally so that they don't
7720 grow indefinitely; the best way to do this is to drop a log
7721 rotation configuration file into the directory
7722 <file>/etc/logrotate.d</file> and use the facilities provided by
7723 logrotate.<footnote>
7725 The traditional approach to log files has been to set up
7726 <em>ad hoc</em> log rotation schemes using simple shell
7727 scripts and cron. While this approach is highly
7728 customizable, it requires quite a lot of sysadmin work.
7729 Even though the original Debian system helped a little
7730 by automatically installing a system which can be used
7731 as a template, this was deemed not enough.
7735 The use of <prgn>logrotate</prgn>, a program developed
7736 by Red Hat, is better, as it centralizes log management.
7737 It has both a configuration file
7738 (<file>/etc/logrotate.conf</file>) and a directory where
7739 packages can drop their individual log rotation
7740 configurations (<file>/etc/logrotate.d</file>).
7743 Here is a good example for a logrotate config
7744 file (for more information see <manref name="logrotate"
7746 <example compact="compact">
7747 /var/log/foo/*.log {
7752 /etc/init.d/foo force-reload
7756 This rotates all files under <file>/var/log/foo</file>, saves 12
7757 compressed generations, and forces the daemon to reload its
7758 configuration information after the log rotation.
7762 Log files should be removed when the package is
7763 purged (but not when it is only removed). This should be
7764 done by the <prgn>postrm</prgn> script when it is called
7765 with the argument <tt>purge</tt> (see <ref
7766 id="removedetails">).
7771 <heading>Permissions and owners</heading>
7774 The rules in this section are guidelines for general use.
7775 If necessary you may deviate from the details below.
7776 However, if you do so you must make sure that what is done
7777 is secure and you should try to be as consistent as possible
7778 with the rest of the system. You should probably also
7779 discuss it on <prgn>debian-devel</prgn> first.
7783 Files should be owned by <tt>root:root</tt>, and made
7784 writable only by the owner and universally readable (and
7785 executable, if appropriate), that is mode 644 or 755.
7789 Directories should be mode 755 or (for group-writability)
7790 mode 2775. The ownership of the directory should be
7791 consistent with its mode: if a directory is mode 2775, it
7792 should be owned by the group that needs write access to
7795 When a package is upgraded, and the owner or permissions
7796 of a file included in the package has changed, dpkg
7797 arranges for the ownership and permissions to be
7798 correctly set upon installation. However, this does not
7799 extend to directories; the permissions and ownership of
7800 directories already on the system does not change on
7801 install or upgrade of packages. This makes sense, since
7802 otherwise common directories like <tt>/usr</tt> would
7803 always be in flux. To correctly change permissions of a
7804 directory the package owns, explicit action is required,
7805 usually in the <tt>postinst</tt> script. Care must be
7806 taken to handle downgrades as well, in that case.
7813 Setuid and setgid executables should be mode 4755 or 2755
7814 respectively, and owned by the appropriate user or group.
7815 They should not be made unreadable (modes like 4711 or
7816 2711 or even 4111); doing so achieves no extra security,
7817 because anyone can find the binary in the freely available
7818 Debian package; it is merely inconvenient. For the same
7819 reason you should not restrict read or execute permissions
7820 on non-set-id executables.
7824 Some setuid programs need to be restricted to particular
7825 sets of users, using file permissions. In this case they
7826 should be owned by the uid to which they are set-id, and by
7827 the group which should be allowed to execute them. They
7828 should have mode 4754; again there is no point in making
7829 them unreadable to those users who must not be allowed to
7834 It is possible to arrange that the system administrator can
7835 reconfigure the package to correspond to their local
7836 security policy by changing the permissions on a binary:
7837 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7838 described below.<footnote>
7839 Ordinary files installed by <prgn>dpkg</prgn> (as
7840 opposed to <tt>conffile</tt>s and other similar objects)
7841 normally have their permissions reset to the distributed
7842 permissions when the package is reinstalled. However,
7843 the use of <prgn>dpkg-statoverride</prgn> overrides this
7846 Another method you should consider is to create a group for
7847 people allowed to use the program(s) and make any setuid
7848 executables executable only by that group.
7852 If you need to create a new user or group for your package
7853 there are two possibilities. Firstly, you may need to
7854 make some files in the binary package be owned by this
7855 user or group, or you may need to compile the user or
7856 group id (rather than just the name) into the binary
7857 (though this latter should be avoided if possible, as in
7858 this case you need a statically allocated id).</p>
7861 If you need a statically allocated id, you must ask for a
7862 user or group id from the <tt>base-passwd</tt> maintainer,
7863 and must not release the package until you have been
7864 allocated one. Once you have been allocated one you must
7865 either make the package depend on a version of the
7866 <tt>base-passwd</tt> package with the id present in
7867 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7868 your package to create the user or group itself with the
7869 correct id (using <tt>adduser</tt>) in its
7870 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7871 the <prgn>postinst</prgn> is to be preferred if it is
7872 possible, otherwise a pre-dependency will be needed on the
7873 <tt>adduser</tt> package.)
7877 On the other hand, the program might be able to determine
7878 the uid or gid from the user or group name at runtime, so
7879 that a dynamically allocated id can be used. In this case
7880 you should choose an appropriate user or group name,
7881 discussing this on <prgn>debian-devel</prgn> and checking
7882 with the <package/base-passwd/ maintainer that it is unique and that
7883 they do not wish you to use a statically allocated id
7884 instead. When this has been checked you must arrange for
7885 your package to create the user or group if necessary using
7886 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7887 <prgn>postinst</prgn> script (again, the latter is to be
7888 preferred if it is possible).
7892 Note that changing the numeric value of an id associated
7893 with a name is very difficult, and involves searching the
7894 file system for all appropriate files. You need to think
7895 carefully whether a static or dynamic id is required, since
7896 changing your mind later will cause problems.
7899 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7901 This section is not intended as policy, but as a
7902 description of the use of <prgn>dpkg-statoverride</prgn>.
7906 If a system administrator wishes to have a file (or
7907 directory or other such thing) installed with owner and
7908 permissions different from those in the distributed Debian
7909 package, they can use the <prgn>dpkg-statoverride</prgn>
7910 program to instruct <prgn>dpkg</prgn> to use the different
7911 settings every time the file is installed. Thus the
7912 package maintainer should distribute the files with their
7913 normal permissions, and leave it for the system
7914 administrator to make any desired changes. For example, a
7915 daemon which is normally required to be setuid root, but
7916 in certain situations could be used without being setuid,
7917 should be installed setuid in the <tt>.deb</tt>. Then the
7918 local system administrator can change this if they wish.
7919 If there are two standard ways of doing it, the package
7920 maintainer can use <tt>debconf</tt> to find out the
7921 preference, and call <prgn>dpkg-statoverride</prgn> in the
7922 maintainer script if necessary to accommodate the system
7923 administrator's choice. Care must be taken during
7924 upgrades to not override an existing setting.
7928 Given the above, <prgn>dpkg-statoverride</prgn> is
7929 essentially a tool for system administrators and would not
7930 normally be needed in the maintainer scripts. There is
7931 one type of situation, though, where calls to
7932 <prgn>dpkg-statoverride</prgn> would be needed in the
7933 maintainer scripts, and that involves packages which use
7934 dynamically allocated user or group ids. In such a
7935 situation, something like the following idiom can be very
7936 helpful in the package's <prgn>postinst</prgn>, where
7937 <tt>sysuser</tt> is a dynamically allocated id:
7939 for i in /usr/bin/foo /usr/sbin/bar
7941 # only do something when no setting exists
7942 if ! dpkg-statoverride --list $i >/dev/null 2>&1
7944 #include: debconf processing, question about foo and bar
7945 if [ "$RET" = "true" ] ; then
7946 dpkg-statoverride --update --add sysuser root 4755 $i
7951 The corresponding code to remove the override when the package
7954 for i in /usr/bin/foo /usr/sbin/bar
7956 if dpkg-statoverride --list $i >/dev/null 2>&1
7958 dpkg-statoverride --remove $i
7968 <chapt id="customized-programs">
7969 <heading>Customized programs</heading>
7971 <sect id="arch-spec">
7972 <heading>Architecture specification strings</heading>
7975 If a program needs to specify an <em>architecture specification
7976 string</em> in some place, it should select one of the strings
7977 provided by <tt>dpkg-architecture -L</tt>. The strings are in
7978 the format <tt><var>os</var>-<var>arch</var></tt>, though the OS
7979 part is sometimes elided, as when the OS is Linux.
7983 Note that we don't want to use
7984 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7985 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7986 since this would make our programs incompatible with other
7987 Linux distributions. We also don't use something like
7988 <tt><var>arch</var>-unknown-linux</tt>, since the
7989 <tt>unknown</tt> does not look very good.
7992 <sect1 id="arch-wildcard-spec">
7993 <heading>Architecture wildcards</heading>
7996 A package may specify an architecture wildcard. Architecture
7997 wildcards are in the format <tt>any</tt> (which matches every
7998 architecture), <tt><var>os</var></tt>-any, or
7999 any-<tt><var>cpu</var></tt>. <footnote>
8000 Internally, the package system normalizes the GNU triplets
8001 and the Debian arches into Debian arch triplets (which are
8002 kind of inverted GNU triplets), with the first component of
8003 the triplet representing the libc and ABI in use, and then
8004 does matching against those triplets. However, such
8005 triplets are an internal implementation detail that should
8006 not be used by packages directly. The libc and ABI portion
8007 is handled internally by the package system based on
8008 the <var>os</var> and <var>cpu</var>.
8015 <heading>Daemons</heading>
8018 The configuration files <file>/etc/services</file>,
8019 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
8020 by the <prgn>netbase</prgn> package and must not be modified
8025 If a package requires a new entry in one of these files, the
8026 maintainer should get in contact with the
8027 <prgn>netbase</prgn> maintainer, who will add the entries
8028 and release a new version of the <prgn>netbase</prgn>
8033 The configuration file <file>/etc/inetd.conf</file> must not be
8034 modified by the package's scripts except via the
8035 <prgn>update-inetd</prgn> script or the
8036 <file>DebianNet.pm</file> Perl module. See their documentation
8037 for details on how to add entries.
8041 If a package wants to install an example entry into
8042 <file>/etc/inetd.conf</file>, the entry must be preceded with
8043 exactly one hash character (<tt>#</tt>). Such lines are
8044 treated as "commented out by user" by the
8045 <prgn>update-inetd</prgn> script and are not changed or
8046 activated during package updates.
8051 <heading>Using pseudo-ttys and modifying wtmp, utmp and
8055 Some programs need to create pseudo-ttys. This should be done
8056 using Unix98 ptys if the C library supports it. The resulting
8057 program must not be installed setuid root, unless that
8058 is required for other functionality.
8062 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
8063 <file>/var/log/lastlog</file> must be installed writable by
8064 group <tt>utmp</tt>. Programs which need to modify those
8065 files must be installed setgid <tt>utmp</tt>.
8070 <heading>Editors and pagers</heading>
8073 Some programs have the ability to launch an editor or pager
8074 program to edit or display a text document. Since there are
8075 lots of different editors and pagers available in the Debian
8076 distribution, the system administrator and each user should
8077 have the possibility to choose their preferred editor and
8082 In addition, every program should choose a good default
8083 editor/pager if none is selected by the user or system
8088 Thus, every program that launches an editor or pager must
8089 use the EDITOR or PAGER environment variable to determine
8090 the editor or pager the user wishes to use. If these
8091 variables are not set, the programs <file>/usr/bin/editor</file>
8092 and <file>/usr/bin/pager</file> should be used, respectively.
8096 These two files are managed through the <prgn>dpkg</prgn>
8097 "alternatives" mechanism. Thus every package providing an
8098 editor or pager must call the
8099 <prgn>update-alternatives</prgn> script to register these
8104 If it is very hard to adapt a program to make use of the
8105 EDITOR or PAGER variables, that program may be configured to
8106 use <file>/usr/bin/sensible-editor</file> and
8107 <file>/usr/bin/sensible-pager</file> as the editor or pager
8108 program respectively. These are two scripts provided in the
8109 <package>sensible-utils</package> package that check the EDITOR
8110 and PAGER variables and launch the appropriate program, and fall
8111 back to <file>/usr/bin/editor</file>
8112 and <file>/usr/bin/pager</file> if the variable is not set.
8116 A program may also use the VISUAL environment variable to
8117 determine the user's choice of editor. If it exists, it
8118 should take precedence over EDITOR. This is in fact what
8119 <file>/usr/bin/sensible-editor</file> does.
8123 It is not required for a package to depend on
8124 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
8125 package to provide such virtual packages.<footnote>
8126 The Debian base system already provides an editor and a
8132 <sect id="web-appl">
8133 <heading>Web servers and applications</heading>
8136 This section describes the locations and URLs that should
8137 be used by all web servers and web applications in the
8144 Cgi-bin executable files are installed in the
8146 <example compact="compact">
8147 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
8149 and should be referred to as
8150 <example compact="compact">
8151 http://localhost/cgi-bin/<var>cgi-bin-name</var>
8157 <p>Access to HTML documents</p>
8160 HTML documents for a package are stored in
8161 <file>/usr/share/doc/<var>package</var></file>
8162 and can be referred to as
8163 <example compact="compact">
8164 http://localhost/doc/<var>package</var>/<var>filename</var>
8169 The web server should restrict access to the document
8170 tree so that only clients on the same host can read
8171 the documents. If the web server does not support such
8172 access controls, then it should not provide access at
8173 all, or ask about providing access during installation.
8178 <p>Access to images</p>
8180 It is recommended that images for a package be stored
8181 in <tt>/usr/share/images/<var>package</var></tt> and
8182 may be referred to through an alias <tt>/images/</tt>
8185 http://localhost/images/<package>/<filename>
8192 <p>Web Document Root</p>
8195 Web Applications should try to avoid storing files in
8196 the Web Document Root. Instead they should use the
8197 /usr/share/doc/<var>package</var> directory for
8198 documents and register the Web Application via the
8199 <package>doc-base</package> package. If access to the
8200 web document root is unavoidable then use
8201 <example compact="compact">
8204 as the Document Root. This might be just a symbolic
8205 link to the location where the system administrator
8206 has put the real document root.
8209 <item><p>Providing httpd and/or httpd-cgi</p>
8211 All web servers should provide the virtual package
8212 <tt>httpd</tt>. If a web server has CGI support it should
8213 provide <tt>httpd-cgi</tt> additionally.
8216 All web applications which do not contain CGI scripts should
8217 depend on <tt>httpd</tt>, all those web applications which
8218 <tt>do</tt> contain CGI scripts, should depend on
8226 <sect id="mail-transport-agents">
8227 <heading>Mail transport, delivery and user agents</heading>
8230 Debian packages which process electronic mail, whether mail
8231 user agents (MUAs) or mail transport agents (MTAs), must
8232 ensure that they are compatible with the configuration
8233 decisions below. Failure to do this may result in lost
8234 mail, broken <tt>From:</tt> lines, and other serious brain
8239 The mail spool is <file>/var/mail</file> and the interface to
8240 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8241 the FHS). On older systems, the mail spool may be
8242 physically located in <file>/var/spool/mail</file>, but all
8243 access to the mail spool should be via the
8244 <file>/var/mail</file> symlink. The mail spool is part of the
8245 base system and not part of the MTA package.
8249 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8250 programs (such as IMAP daemons) must lock the mailbox in an
8251 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8252 be combined with dot locking. To avoid deadlocks, a program
8253 should use <tt>fcntl()</tt> first and dot locking after
8254 this, or alternatively implement the two locking methods in
8255 a non blocking way<footnote>
8256 If it is not possible to establish both locks, the
8257 system shouldn't wait for the second lock to be
8258 established, but remove the first lock, wait a (random)
8259 time, and start over locking again.
8260 </footnote>. Using the functions <tt>maillock</tt> and
8261 <tt>mailunlock</tt> provided by the
8262 <tt>liblockfile*</tt><footnote>
8263 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8264 to use these functions.
8265 </footnote> packages is the recommended way to realize this.
8269 Mailboxes are generally either mode 600 and owned by
8270 <var>user</var> or mode 660 and owned by
8271 <tt><var>user</var>:mail</tt><footnote>
8272 There are two traditional permission schemes for mail spools:
8273 mode 600 with all mail delivery done by processes running as
8274 the destination user, or mode 660 and owned by group mail with
8275 mail delivery done by a process running as a system user in
8276 group mail. Historically, Debian required mode 660 mail
8277 spools to enable the latter model, but that model has become
8278 increasingly uncommon and the principle of least privilege
8279 indicates that mail systems that use the first model should
8280 use permissions of 600. If delivery to programs is permitted,
8281 it's easier to keep the mail system secure if the delivery
8282 agent runs as the destination user. Debian Policy therefore
8283 permits either scheme.
8284 </footnote>. The local system administrator may choose a
8285 different permission scheme; packages should not make
8286 assumptions about the permission and ownership of mailboxes
8287 unless required (such as when creating a new mailbox). A MUA
8288 may remove a mailbox (unless it has nonstandard permissions) in
8289 which case the MTA or another MUA must recreate it if needed.
8293 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8294 be setgid mail to do the locking mentioned above (and
8295 must obviously avoid accessing other users' mailboxes
8296 using this privilege).</p>
8299 <file>/etc/aliases</file> is the source file for the system mail
8300 aliases (e.g., postmaster, usenet, etc.), it is the one
8301 which the sysadmin and <prgn>postinst</prgn> scripts may
8302 edit. After <file>/etc/aliases</file> is edited the program or
8303 human editing it must call <prgn>newaliases</prgn>. All MTA
8304 packages must come with a <prgn>newaliases</prgn> program,
8305 even if it does nothing, but older MTA packages did not do
8306 this so programs should not fail if <prgn>newaliases</prgn>
8307 cannot be found. Note that because of this, all MTA
8308 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8309 <tt>Replaces: mail-transport-agent</tt> control file
8314 The convention of writing <tt>forward to
8315 <var>address</var></tt> in the mailbox itself is not
8316 supported. Use a <tt>.forward</tt> file instead.</p>
8319 The <prgn>rmail</prgn> program used by UUCP
8320 for incoming mail should be <file>/usr/sbin/rmail</file>.
8321 Likewise, <prgn>rsmtp</prgn>, for receiving
8322 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8326 If your package needs to know what hostname to use on (for
8327 example) outgoing news and mail messages which are generated
8328 locally, you should use the file <file>/etc/mailname</file>. It
8329 will contain the portion after the username and <tt>@</tt>
8330 (at) sign for email addresses of users on the machine
8331 (followed by a newline).
8335 Such a package should check for the existence of this file
8336 when it is being configured. If it exists, it should be
8337 used without comment, although an MTA's configuration script
8338 may wish to prompt the user even if it finds that this file
8339 exists. If the file does not exist, the package should
8340 prompt the user for the value (preferably using
8341 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8342 as well as using it in the package's configuration. The
8343 prompt should make it clear that the name will not just be
8344 used by that package. For example, in this situation the
8345 <tt>inn</tt> package could say something like:
8346 <example compact="compact">
8347 Please enter the "mail name" of your system. This is the
8348 hostname portion of the address to be shown on outgoing
8349 news and mail messages. The default is
8350 <var>syshostname</var>, your system's host name. Mail
8351 name ["<var>syshostname</var>"]:
8353 where <var>syshostname</var> is the output of <tt>hostname
8359 <heading>News system configuration</heading>
8362 All the configuration files related to the NNTP (news)
8363 servers and clients should be located under
8364 <file>/etc/news</file>.</p>
8367 There are some configuration issues that apply to a number
8368 of news clients and server packages on the machine. These
8372 <tag><file>/etc/news/organization</file></tag>
8374 A string which should appear as the
8375 organization header for all messages posted
8376 by NNTP clients on the machine
8379 <tag><file>/etc/news/server</file></tag>
8381 Contains the FQDN of the upstream NNTP
8382 server, or localhost if the local machine is
8387 Other global files may be added as required for cross-package news
8394 <heading>Programs for the X Window System</heading>
8397 <heading>Providing X support and package priorities</heading>
8400 Programs that can be configured with support for the X
8401 Window System must be configured to do so and must declare
8402 any package dependencies necessary to satisfy their
8403 runtime requirements when using the X Window System. If
8404 such a package is of higher priority than the X packages
8405 on which it depends, it is required that either the
8406 X-specific components be split into a separate package, or
8407 that an alternative version of the package, which includes
8408 X support, be provided, or that the package's priority be
8414 <heading>Packages providing an X server</heading>
8417 Packages that provide an X server that, directly or
8418 indirectly, communicates with real input and display
8419 hardware should declare in their control data that they
8420 provide the virtual package <tt>xserver</tt>.<footnote>
8421 This implements current practice, and provides an
8422 actual policy for usage of the <tt>xserver</tt>
8423 virtual package which appears in the virtual packages
8424 list. In a nutshell, X servers that interface
8425 directly with the display and input hardware or via
8426 another subsystem (e.g., GGI) should provide
8427 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8428 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8434 <heading>Packages providing a terminal emulator</heading>
8437 Packages that provide a terminal emulator for the X Window
8438 System which meet the criteria listed below should declare
8439 in their control data that they provide the virtual
8440 package <tt>x-terminal-emulator</tt>. They should also
8441 register themselves as an alternative for
8442 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8447 To be an <tt>x-terminal-emulator</tt>, a program must:
8448 <list compact="compact">
8450 Be able to emulate a DEC VT100 terminal, or a
8451 compatible terminal.
8455 Support the command-line option <tt>-e
8456 <var>command</var></tt>, which creates a new
8457 terminal window<footnote>
8458 "New terminal window" does not necessarily mean
8459 a new top-level X window directly parented by
8460 the window manager; it could, if the terminal
8461 emulator application were so coded, be a new
8462 "view" in a multiple-document interface (MDI).
8464 and runs the specified <var>command</var>,
8465 interpreting the entirety of the rest of the command
8466 line as a command to pass straight to exec, in the
8467 manner that <tt>xterm</tt> does.
8471 Support the command-line option <tt>-T
8472 <var>title</var></tt>, which creates a new terminal
8473 window with the window title <var>title</var>.
8480 <heading>Packages providing a window manager</heading>
8483 Packages that provide a window manager should declare in
8484 their control data that they provide the virtual package
8485 <tt>x-window-manager</tt>. They should also register
8486 themselves as an alternative for
8487 <file>/usr/bin/x-window-manager</file>, with a priority
8488 calculated as follows:
8489 <list compact="compact">
8491 Start with a priority of 20.
8495 If the window manager supports the Debian menu
8496 system, add 20 points if this support is available
8497 in the package's default configuration (i.e., no
8498 configuration files belonging to the system or user
8499 have to be edited to activate the feature); if
8500 configuration files must be modified, add only 10
8506 If the window manager complies with <url
8507 id="http://www.freedesktop.org/Standards/wm-spec"
8508 name="The Window Manager Specification Project">,
8509 written by the <url id="http://www.freedesktop.org/"
8510 name="Free Desktop Group">, add 40 points.
8514 If the window manager permits the X session to be
8515 restarted using a <em>different</em> window manager
8516 (without killing the X server) in its default
8517 configuration, add 10 points; otherwise add none.
8524 <heading>Packages providing fonts</heading>
8527 Packages that provide fonts for the X Window
8529 For the purposes of Debian Policy, a "font for the X
8530 Window System" is one which is accessed via X protocol
8531 requests. Fonts for the Linux console, for PostScript
8532 renderer, or any other purpose, do not fit this
8533 definition. Any tool which makes such fonts available
8534 to the X Window System, however, must abide by this
8537 must do a number of things to ensure that they are both
8538 available without modification of the X or font server
8539 configuration, and that they do not corrupt files used by
8540 other font packages to register information about
8544 Fonts of any type supported by the X Window System
8545 must be in a separate binary package from any
8546 executables, libraries, or documentation (except
8547 that specific to the fonts shipped, such as their
8548 license information). If one or more of the fonts
8549 so packaged are necessary for proper operation of
8550 the package with which they are associated the font
8551 package may be Recommended; if the fonts merely
8552 provide an enhancement, a Suggests relationship may
8553 be used. Packages must not Depend on font
8555 This is because the X server may retrieve fonts
8556 from the local file system or over the network
8557 from an X font server; the Debian package system
8558 is empowered to deal only with the local
8564 BDF fonts must be converted to PCF fonts with the
8565 <prgn>bdftopcf</prgn> utility (available in the
8566 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8567 placed in a directory that corresponds to their
8569 <list compact="compact">
8571 100 dpi fonts must be placed in
8572 <file>/usr/share/fonts/X11/100dpi/</file>.
8576 75 dpi fonts must be placed in
8577 <file>/usr/share/fonts/X11/75dpi/</file>.
8581 Character-cell fonts, cursor fonts, and other
8582 low-resolution fonts must be placed in
8583 <file>/usr/share/fonts/X11/misc/</file>.
8589 Type 1 fonts must be placed in
8590 <file>/usr/share/fonts/X11/Type1/</file>. If font
8591 metric files are available, they must be placed here
8596 Subdirectories of <file>/usr/share/fonts/X11/</file>
8597 other than those listed above must be neither
8598 created nor used. (The <file>PEX</file>, <file>CID</file>,
8599 <file>Speedo</file>, and <file>cyrillic</file> directories
8600 are excepted for historical reasons, but installation of
8601 files into these directories remains discouraged.)
8605 Font packages may, instead of placing files directly
8606 in the X font directories listed above, provide
8607 symbolic links in that font directory pointing to
8608 the files' actual location in the filesystem. Such
8609 a location must comply with the FHS.
8613 Font packages should not contain both 75dpi and
8614 100dpi versions of a font. If both are available,
8615 they should be provided in separate binary packages
8616 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8617 the names of the packages containing the
8618 corresponding fonts.
8622 Fonts destined for the <file>misc</file> subdirectory
8623 should not be included in the same package as 75dpi
8624 or 100dpi fonts; instead, they should be provided in
8625 a separate package with <tt>-misc</tt> appended to
8630 Font packages must not provide the files
8631 <file>fonts.dir</file>, <file>fonts.alias</file>, or
8632 <file>fonts.scale</file> in a font directory:
8635 <file>fonts.dir</file> files must not be provided at all.
8639 <file>fonts.alias</file> and <file>fonts.scale</file>
8640 files, if needed, should be provided in the
8642 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
8643 where <var>fontdir</var> is the name of the
8645 <file>/usr/share/fonts/X11/</file> where the
8646 package's corresponding fonts are stored
8647 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
8648 <var>package</var> is the name of the package
8649 that provides these fonts, and
8650 <var>extension</var> is either <tt>scale</tt>
8651 or <tt>alias</tt>, whichever corresponds to
8658 Font packages must declare a dependency on
8659 <tt>xfonts-utils</tt> in their control
8664 Font packages that provide one or more
8665 <file>fonts.scale</file> files as described above must
8666 invoke <prgn>update-fonts-scale</prgn> on each
8667 directory into which they installed fonts
8668 <em>before</em> invoking
8669 <prgn>update-fonts-dir</prgn> on that directory.
8670 This invocation must occur in both the
8671 <prgn>postinst</prgn> (for all arguments) and
8672 <prgn>postrm</prgn> (for all arguments except
8673 <tt>upgrade</tt>) scripts.
8677 Font packages that provide one or more
8678 <file>fonts.alias</file> files as described above must
8679 invoke <prgn>update-fonts-alias</prgn> on each
8680 directory into which they installed fonts. This
8681 invocation must occur in both the
8682 <prgn>postinst</prgn> (for all arguments) and
8683 <prgn>postrm</prgn> (for all arguments except
8684 <tt>upgrade</tt>) scripts.
8688 Font packages must invoke
8689 <prgn>update-fonts-dir</prgn> on each directory into
8690 which they installed fonts. This invocation must
8691 occur in both the <prgn>postinst</prgn> (for all
8692 arguments) and <prgn>postrm</prgn> (for all
8693 arguments except <tt>upgrade</tt>) scripts.
8697 Font packages must not provide alias names for the
8698 fonts they include which collide with alias names
8699 already in use by fonts already packaged.
8703 Font packages must not provide fonts with the same
8704 XLFD registry name as another font already packaged.
8710 <sect1 id="appdefaults">
8711 <heading>Application defaults files</heading>
8714 Application defaults files must be installed in the
8715 directory <file>/etc/X11/app-defaults/</file> (use of a
8716 localized subdirectory of <file>/etc/X11/</file> as described
8717 in the <em>X Toolkit Intrinsics - C Language
8718 Interface</em> manual is also permitted). They must be
8719 registered as <tt>conffile</tt>s or handled as
8720 configuration files.
8724 Customization of programs' X resources may also be
8725 supported with the provision of a file with the same name
8726 as that of the package placed in
8727 the <file>/etc/X11/Xresources/</file> directory, which
8728 must be registered as a <tt>conffile</tt> or handled as a
8729 configuration file.<footnote>
8730 Note that this mechanism is not the same as using
8731 app-defaults; app-defaults are tied to the client
8732 binary on the local file system, whereas X resources
8733 are stored in the X server and affect all connecting
8740 <heading>Installation directory issues</heading>
8743 Historically, packages using the X Window System used a
8744 separate set of installation directories from other packages.
8745 This practice has been discontinued and packages using the X
8746 Window System should now generally be installed in the same
8747 directories as any other package. Specifically, packages must
8748 not install files under the <file>/usr/X11R6/</file> directory
8749 and the <file>/usr/X11R6/</file> directory hierarchy should be
8750 regarded as obsolete.
8754 Include files previously installed under
8755 <file>/usr/X11R6/include/X11/</file> should be installed into
8756 <file>/usr/include/X11/</file>. For files previously
8757 installed into subdirectories of
8758 <file>/usr/X11R6/lib/X11/</file>, package maintainers should
8759 determine if subdirectories of <file>/usr/lib/</file> and
8760 <file>/usr/share/</file> can be used. If not, a subdirectory
8761 of <file>/usr/lib/X11/</file> should be used.
8765 Configuration files for window, display, or session managers
8766 or other applications that are tightly integrated with the X
8767 Window System may be placed in a subdirectory
8768 of <file>/etc/X11/</file> corresponding to the package name.
8769 Other X Window System applications should use
8770 the <file>/etc/</file> directory unless otherwise mandated by
8771 policy (such as for <ref id="appdefaults">).
8776 <heading>The OSF/Motif and OpenMotif libraries</heading>
8779 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8780 OpenMotif libraries</em><footnote>
8781 OSF/Motif and OpenMotif are collectively referred to as
8782 "Motif" in this policy document.
8784 should be compiled against and tested with LessTif (a free
8785 re-implementation of Motif) instead. If the maintainer
8786 judges that the program or programs do not work
8787 sufficiently well with LessTif to be distributed and
8788 supported, but do so when compiled against Motif, then two
8789 versions of the package should be created; one linked
8790 statically against Motif and with <tt>-smotif</tt>
8791 appended to the package name, and one linked dynamically
8792 against Motif and with <tt>-dmotif</tt> appended to the
8797 Both Motif-linked versions are dependent
8798 upon non-DFSG-compliant software and thus cannot be
8799 uploaded to the <em>main</em> distribution; if the
8800 software is itself DFSG-compliant it may be uploaded to
8801 the <em>contrib</em> distribution. While known existing
8802 versions of Motif permit unlimited redistribution of
8803 binaries linked against the library (whether statically or
8804 dynamically), it is the package maintainer's
8805 responsibility to determine whether this is permitted by
8806 the license of the copy of Motif in their possession.
8812 <heading>Perl programs and modules</heading>
8815 Perl programs and modules should follow the current Perl policy.
8819 The Perl policy can be found in the <tt>perl-policy</tt>
8820 files in the <tt>debian-policy</tt> package.
8821 It is also available from the Debian web mirrors at
8822 <tt><url name="/doc/packaging-manuals/perl-policy/"
8823 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8828 <heading>Emacs lisp programs</heading>
8831 Please refer to the "Debian Emacs Policy" for details of how to
8832 package emacs lisp programs.
8836 The Emacs policy is available in
8837 <file>debian-emacs-policy.gz</file> of the
8838 <package>emacsen-common</package> package.
8839 It is also available from the Debian web mirrors at
8840 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8841 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8846 <heading>Games</heading>
8849 The permissions on <file>/var/games</file> are mode 755, owner
8850 <tt>root</tt> and group <tt>root</tt>.
8854 Each game decides on its own security policy.</p>
8857 Games which require protected, privileged access to
8858 high-score files, saved games, etc., may be made
8859 set-<em>group</em>-id (mode 2755) and owned by
8860 <tt>root:games</tt>, and use files and directories with
8861 appropriate permissions (770 <tt>root:games</tt>, for
8862 example). They must not be made
8863 set-<em>user</em>-id, as this causes security problems. (If
8864 an attacker can subvert any set-user-id game they can
8865 overwrite the executable of any other, causing other players
8866 of these games to run a Trojan horse program. With a
8867 set-group-id game the attacker only gets access to less
8868 important game data, and if they can get at the other
8869 players' accounts at all it will take considerably more
8873 Some packages, for example some fortune cookie programs, are
8874 configured by the upstream authors to install with their
8875 data files or other static information made unreadable so
8876 that they can only be accessed through set-id programs
8877 provided. You should not do this in a Debian package: anyone can
8878 download the <file>.deb</file> file and read the data from it,
8879 so there is no point making the files unreadable. Not
8880 making the files unreadable also means that you don't have
8881 to make so many programs set-id, which reduces the risk of a
8885 As described in the FHS, binaries of games should be
8886 installed in the directory <file>/usr/games</file>. This also
8887 applies to games that use the X Window System. Manual pages
8888 for games (X and non-X games) should be installed in
8889 <file>/usr/share/man/man6</file>.</p>
8895 <heading>Documentation</heading>
8898 <heading>Manual pages</heading>
8901 You should install manual pages in <prgn>nroff</prgn> source
8902 form, in appropriate places under <file>/usr/share/man</file>.
8903 You should only use sections 1 to 9 (see the FHS for more
8904 details). You must not install a pre-formatted "cat page".
8908 Each program, utility, and function should have an
8909 associated manual page included in the same package. It is
8910 suggested that all configuration files also have a manual
8911 page included as well. Manual pages for protocols and other
8912 auxiliary things are optional.
8916 If no manual page is available, this is considered as a bug
8917 and should be reported to the Debian Bug Tracking System (the
8918 maintainer of the package is allowed to write this bug report
8919 themselves, if they so desire). Do not close the bug report
8920 until a proper man page is available.<footnote>
8921 It is not very hard to write a man page. See the
8922 <url id="http://www.schweikhardt.net/man_page_howto.html"
8923 name="Man-Page-HOWTO">,
8924 <manref name="man" section="7">, the examples
8925 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8926 the helper programs <prgn>help2man</prgn>, or the
8927 directory <file>/usr/share/doc/man-db/examples</file>.
8932 You may forward a complaint about a missing man page to the
8933 upstream authors, and mark the bug as forwarded in the
8934 Debian bug tracking system. Even though the GNU Project do
8935 not in general consider the lack of a man page to be a bug,
8936 we do; if they tell you that they don't consider it a bug
8937 you should leave the bug in our bug tracking system open
8942 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8946 If one man page needs to be accessible via several names it
8947 is better to use a symbolic link than the <file>.so</file>
8948 feature, but there is no need to fiddle with the relevant
8949 parts of the upstream source to change from <file>.so</file> to
8950 symlinks: don't do it unless it's easy. You should not
8951 create hard links in the manual page directories, nor put
8952 absolute filenames in <file>.so</file> directives. The filename
8953 in a <file>.so</file> in a man page should be relative to the
8954 base of the man page tree (usually
8955 <file>/usr/share/man</file>). If you do not create any links
8956 (whether symlinks, hard links, or <tt>.so</tt> directives)
8957 in the file system to the alternate names of the man page,
8958 then you should not rely on <prgn>man</prgn> finding your
8959 man page under those names based solely on the information in
8960 the man page's header.<footnote>
8961 Supporting this in <prgn>man</prgn> often requires
8962 unreasonable processing time to find a manual page or to
8963 report that none exists, and moves knowledge into man's
8964 database that would be better left in the file system.
8965 This support is therefore deprecated and will cease to
8966 be present in the future.
8971 Manual pages in locale-specific subdirectories of
8972 <file>/usr/share/man</file> should use either UTF-8 or the usual
8973 legacy encoding for that language (normally the one corresponding
8974 to the shortest relevant locale name in
8975 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
8976 <file>/usr/share/man/fr</file> should use either UTF-8 or
8977 ISO-8859-1.<footnote>
8978 <prgn>man</prgn> will automatically detect whether UTF-8 is in
8979 use. In future, all manual pages will be required to use
8985 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
8986 included in the subdirectory name unless it indicates a
8987 significant difference in the language, as this excludes
8988 speakers of the language in other countries.<footnote>
8989 At the time of writing, Chinese and Portuguese are the main
8990 languages with such differences, so <file>pt_BR</file>,
8991 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
8996 If a localized version of a manual page is provided, it should
8997 either be up-to-date or it should be obvious to the reader that
8998 it is outdated and the original manual page should be used
8999 instead. This can be done either by a note at the beginning of
9000 the manual page or by showing the missing or changed portions in
9001 the original language instead of the target language.
9006 <heading>Info documents</heading>
9009 Info documents should be installed in <file>/usr/share/info</file>.
9010 They should be compressed with <tt>gzip -9</tt>.
9014 The <prgn>install-info</prgn> program maintains a directory of
9015 installed info documents in <file>/usr/share/info/dir</file> for
9016 the use of info readers.<footnote>
9017 It was previously necessary for packages installing info
9018 documents to run <prgn>install-info</prgn> from maintainer
9019 scripts. This is no longer necessary. The installation
9020 system now uses dpkg triggers.
9022 This file must not be included in packages. Packages containing
9023 info documents should depend on <tt>dpkg (>= 1.15.4) |
9024 install-info</tt> to ensure that the directory file is properly
9025 rebuilt during partial upgrades from Debian 5.0 (lenny) and
9030 Info documents should contain section and directory entry
9031 information in the document for the use
9032 of <prgn>install-info</prgn>. The section should be specified
9033 via a line starting with <tt>INFO-DIR-SECTION</tt> followed by a
9034 space and the section of this info page. The directory entry or
9035 entries should be included between
9036 a <tt>START-INFO-DIR-ENTRY</tt> line and
9037 an <tt>END-INFO-DIR-ENTRY</tt> line. For example:
9039 INFO-DIR-SECTION Individual utilities
9040 START-INFO-DIR-ENTRY
9041 * example: (example). An example info directory entry.
9044 To determine which section to use, you should look
9045 at <file>/usr/share/info/dir</file> on your system and choose
9046 the most relevant (or create a new section if none of the
9047 current sections are relevant).<footnote>
9048 Normally, info documents are generated from Texinfo source.
9049 To include this information in the generated info document, if
9050 it is absent, add commands like:
9052 @dircategory Individual utilities
9054 * example: (example). An example info directory entry.
9057 to the Texinfo source of the document and ensure that the info
9058 documents are rebuilt from source during the package build.
9064 <heading>Additional documentation</heading>
9067 Any additional documentation that comes with the package may
9068 be installed at the discretion of the package maintainer.
9069 Plain text documentation should be installed in the directory
9070 <file>/usr/share/doc/<var>package</var></file>, where
9071 <var>package</var> is the name of the package, and
9072 compressed with <tt>gzip -9</tt> unless it is small.
9076 If a package comes with large amounts of documentation which
9077 many users of the package will not require you should create
9078 a separate binary package to contain it, so that it does not
9079 take up disk space on the machines of users who do not need
9080 or want it installed.</p>
9083 It is often a good idea to put text information files
9084 (<file>README</file>s, changelogs, and so forth) that come with
9085 the source package in <file>/usr/share/doc/<var>package</var></file>
9086 in the binary package. However, you don't need to install
9087 the instructions for building and installing the package, of
9091 Packages must not require the existence of any files in
9092 <file>/usr/share/doc/</file> in order to function
9094 The system administrator should be able to
9095 delete files in <file>/usr/share/doc/</file> without causing
9096 any programs to break.
9098 Any files that are referenced by programs but are also
9099 useful as stand alone documentation should be installed under
9100 <file>/usr/share/<var>package</var>/</file> with symbolic links from
9101 <file>/usr/share/doc/<var>package</var></file>.
9105 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9106 link to another directory in <file>/usr/share/doc</file> only if
9107 the two packages both come from the same source and the
9108 first package Depends on the second.<footnote>
9110 Please note that this does not override the section on
9111 changelog files below, so the file
9112 <file>/usr/share/doc/<var>package</var>/changelog.Debian.gz</file>
9113 must refer to the changelog for the current version of
9114 <var>package</var> in question. In practice, this means
9115 that the sources of the target and the destination of the
9116 symlink must be the same (same source package and
9123 Former Debian releases placed all additional documentation
9124 in <file>/usr/doc/<var>package</var></file>. This has been
9125 changed to <file>/usr/share/doc/<var>package</var></file>,
9126 and packages must not put documentation in the directory
9127 <file>/usr/doc/<var>package</var></file>. <footnote>
9128 At this phase of the transition, we no longer require a
9129 symbolic link in <file>/usr/doc/</file>. At a later point,
9130 policy shall change to make the symbolic links a bug.
9136 <heading>Preferred documentation formats</heading>
9139 The unification of Debian documentation is being carried out
9143 If your package comes with extensive documentation in a
9144 markup format that can be converted to various other formats
9145 you should if possible ship HTML versions in a binary
9146 package, in the directory
9147 <file>/usr/share/doc/<var>appropriate-package</var></file> or
9148 its subdirectories.<footnote>
9149 The rationale: The important thing here is that HTML
9150 docs should be available in <em>some</em> package, not
9151 necessarily in the main binary package.
9156 Other formats such as PostScript may be provided at the
9157 package maintainer's discretion.
9161 <sect id="copyrightfile">
9162 <heading>Copyright information</heading>
9165 Every package must be accompanied by a verbatim copy of its
9166 copyright information and distribution license in the file
9167 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
9168 file must neither be compressed nor be a symbolic link.
9172 In addition, the copyright file must say where the upstream
9173 sources (if any) were obtained. It should name the original
9174 authors of the package and the Debian maintainer(s) who were
9175 involved with its creation.
9179 Packages in the <em>contrib</em> or <em>non-free</em> archive
9180 areas should state in the copyright file that the package is not
9181 part of the Debian GNU/Linux distribution and briefly explain
9186 A copy of the file which will be installed in
9187 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9188 be in <file>debian/copyright</file> in the source package.
9192 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9193 link to another directory in <file>/usr/share/doc</file> only if
9194 the two packages both come from the same source and the
9195 first package Depends on the second. These rules are
9196 important because copyrights must be extractable by
9201 Packages distributed under the UCB BSD license, the Apache
9202 license (version 2.0), the Artistic license, the GNU GPL
9203 (version 2 or 3), the GNU LGPL (versions 2, 2.1, or 3), and the
9204 GNU FDL (versions 1.2 or 1.3) should refer to the corresponding
9205 files under <file>/usr/share/common-licenses</file>,<footnote>
9208 <file>/usr/share/common-licenses/BSD</file>,
9209 <file>/usr/share/common-licenses/Apache-2.0</file>,
9210 <file>/usr/share/common-licenses/Artistic</file>,
9211 <file>/usr/share/common-licenses/GPL-2</file>,
9212 <file>/usr/share/common-licenses/GPL-3</file>,
9213 <file>/usr/share/common-licenses/LGPL-2</file>,
9214 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9215 <file>/usr/share/common-licenses/LGPL-3</file>,
9216 <file>/usr/share/common-licenses/GFDL-1.2</file>, and
9217 <file>/usr/share/common-licenses/GFDL-1.3</file>
9220 </footnote> rather than quoting them in the copyright
9225 You should not use the copyright file as a general <file>README</file>
9226 file. If your package has such a file it should be
9227 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9228 <file>README.Debian</file> or some other appropriate place.</p>
9232 <heading>Examples</heading>
9235 Any examples (configurations, source files, whatever),
9236 should be installed in a directory
9237 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9238 files should not be referenced by any program: they're there
9239 for the benefit of the system administrator and users as
9240 documentation only. Architecture-specific example files
9241 should be installed in a directory
9242 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9244 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9245 latter directory itself may be a symbolic link to the
9250 If the purpose of a package is to provide examples, then the
9251 example files may be installed into
9252 <file>/usr/share/doc/<var>package</var></file>.
9256 <sect id="changelogs">
9257 <heading>Changelog files</heading>
9260 Packages that are not Debian-native must contain a
9261 compressed copy of the <file>debian/changelog</file> file from
9262 the Debian source tree in
9263 <file>/usr/share/doc/<var>package</var></file> with the name
9264 <file>changelog.Debian.gz</file>.
9268 If an upstream changelog is available, it should be accessible as
9269 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9270 plain text. If the upstream changelog is distributed in
9271 HTML, it should be made available in that form as
9272 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9273 and a plain text <file>changelog.gz</file> should be generated
9274 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9275 the upstream changelog files do not already conform to this
9276 naming convention, then this may be achieved either by
9277 renaming the files, or by adding a symbolic link, at the
9278 maintainer's discretion.<footnote>
9279 Rationale: People should not have to look in places for
9280 upstream changelogs merely because they are given
9281 different names or are distributed in HTML format.
9286 All of these files should be installed compressed using
9287 <tt>gzip -9</tt>, as they will become large with time even
9288 if they start out small.
9292 If the package has only one changelog which is used both as
9293 the Debian changelog and the upstream one because there is
9294 no separate upstream maintainer then that changelog should
9295 usually be installed as
9296 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9297 there is a separate upstream maintainer, but no upstream
9298 changelog, then the Debian changelog should still be called
9299 <file>changelog.Debian.gz</file>.
9303 For details about the format and contents of the Debian
9304 changelog file, please see <ref id="dpkgchangelog">.
9309 <appendix id="pkg-scope">
9310 <heading>Introduction and scope of these appendices</heading>
9313 These appendices are taken essentially verbatim from the
9314 now-deprecated Packaging Manual, version 3.2.1.0. They are
9315 the chapters which are likely to be of use to package
9316 maintainers and which have not already been included in the
9317 policy document itself. Most of these sections are very likely
9318 not relevant to policy; they should be treated as
9319 documentation for the packaging system. Please note that these
9320 appendices are included for convenience, and for historical
9321 reasons: they used to be part of policy package, and they have
9322 not yet been incorporated into dpkg documentation. However,
9323 they still have value, and hence they are presented here.
9327 They have not yet been checked to ensure that they are
9328 compatible with the contents of policy, and if there are any
9329 contradictions, the version in the main policy document takes
9330 precedence. The remaining chapters of the old Packaging
9331 Manual have also not been read in detail to ensure that there
9332 are not parts which have been left out. Both of these will be
9337 Certain parts of the Packaging manual were integrated into the
9338 Policy Manual proper, and removed from the appendices. Links
9339 have been placed from the old locations to the new ones.
9343 <prgn>dpkg</prgn> is a suite of programs for creating binary
9344 package files and installing and removing them on Unix
9346 <prgn>dpkg</prgn> is targeted primarily at Debian
9347 GNU/Linux, but may work on or be ported to other
9353 The binary packages are designed for the management of
9354 installed executable programs (usually compiled binaries) and
9355 their associated data, though source code examples and
9356 documentation are provided as part of some packages.</p>
9359 This manual describes the technical aspects of creating Debian
9360 binary packages (<file>.deb</file> files). It documents the
9361 behavior of the package management programs
9362 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9363 they interact with packages.</p>
9366 It also documents the interaction between
9367 <prgn>dselect</prgn>'s core and the access method scripts it
9368 uses to actually install the selected packages, and describes
9369 how to create a new access method.</p>
9372 This manual does not go into detail about the options and
9373 usage of the package building and installation tools. It
9374 should therefore be read in conjunction with those programs'
9379 The utility programs which are provided with <prgn>dpkg</prgn>
9380 for managing various system configuration and similar issues,
9381 such as <prgn>update-rc.d</prgn> and
9382 <prgn>install-info</prgn>, are not described in detail here -
9383 please see their man pages.
9387 It is assumed that the reader is reasonably familiar with the
9388 <prgn>dpkg</prgn> System Administrators' manual.
9389 Unfortunately this manual does not yet exist.
9393 The Debian version of the FSF's GNU hello program is provided
9394 as an example for people wishing to create Debian
9395 packages. The Debian <prgn>debmake</prgn> package is
9396 recommended as a very helpful tool in creating and maintaining
9397 Debian packages. However, while the tools and examples are
9398 helpful, they do not replace the need to read and follow the
9399 Policy and Programmer's Manual.</p>
9402 <appendix id="pkg-binarypkg">
9403 <heading>Binary packages (from old Packaging Manual)</heading>
9406 The binary package has two main sections. The first part
9407 consists of various control information files and scripts used
9408 by <prgn>dpkg</prgn> when installing and removing. See <ref
9409 id="pkg-controlarea">.
9413 The second part is an archive containing the files and
9414 directories to be installed.
9418 In the future binary packages may also contain other
9419 components, such as checksums and digital signatures. The
9420 format for the archive is described in full in the
9421 <file>deb(5)</file> man page.
9425 <sect id="pkg-bincreating"><heading>Creating package files -
9426 <prgn>dpkg-deb</prgn>
9430 All manipulation of binary package files is done by
9431 <prgn>dpkg-deb</prgn>; it's the only program that has
9432 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9433 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9434 will spot that the options requested are appropriate to
9435 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9440 In order to create a binary package you must make a
9441 directory tree which contains all the files and directories
9442 you want to have in the file system data part of the package.
9443 In Debian-format source packages this directory is usually
9444 <file>debian/tmp</file>, relative to the top of the package's
9449 They should have the locations (relative to the root of the
9450 directory tree you're constructing) ownerships and
9451 permissions which you want them to have on the system when
9456 With current versions of <prgn>dpkg</prgn> the uid/username
9457 and gid/groupname mappings for the users and groups being
9458 used should be the same on the system where the package is
9459 built and the one where it is installed.
9463 You need to add one special directory to the root of the
9464 miniature file system tree you're creating:
9465 <prgn>DEBIAN</prgn>. It should contain the control
9466 information files, notably the binary package control file
9467 (see <ref id="pkg-controlfile">).
9471 The <prgn>DEBIAN</prgn> directory will not appear in the
9472 file system archive of the package, and so won't be installed
9473 by <prgn>dpkg</prgn> when the package is installed.
9477 When you've prepared the package, you should invoke:
9479 dpkg --build <var>directory</var>
9484 This will build the package in
9485 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9486 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9487 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9492 See the man page <manref name="dpkg-deb" section="8"> for details of how
9493 to examine the contents of this newly-created file. You may find the
9494 output of following commands enlightening:
9496 dpkg-deb --info <var>filename</var>.deb
9497 dpkg-deb --contents <var>filename</var>.deb
9498 dpkg --contents <var>filename</var>.deb
9500 To view the copyright file for a package you could use this command:
9502 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
9507 <sect id="pkg-controlarea">
9508 <heading>Package control information files</heading>
9511 The control information portion of a binary package is a
9512 collection of files with names known to <prgn>dpkg</prgn>.
9513 It will treat the contents of these files specially - some
9514 of them contain information used by <prgn>dpkg</prgn> when
9515 installing or removing the package; others are scripts which
9516 the package maintainer wants <prgn>dpkg</prgn> to run.
9520 It is possible to put other files in the package control
9521 area, but this is not generally a good idea (though they
9522 will largely be ignored).
9526 Here is a brief list of the control info files supported by
9527 <prgn>dpkg</prgn> and a summary of what they're used for.
9532 <tag><tt>control</tt>
9535 This is the key description file used by
9536 <prgn>dpkg</prgn>. It specifies the package's name
9537 and version, gives its description for the user,
9538 states its relationships with other packages, and so
9539 forth. See <ref id="sourcecontrolfiles"> and
9540 <ref id="binarycontrolfiles">.
9544 It is usually generated automatically from information
9545 in the source package by the
9546 <prgn>dpkg-gencontrol</prgn> program, and with
9547 assistance from <prgn>dpkg-shlibdeps</prgn>.
9548 See <ref id="pkg-sourcetools">.
9552 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9557 These are executable files (usually scripts) which
9558 <prgn>dpkg</prgn> runs during installation, upgrade
9559 and removal of packages. They allow the package to
9560 deal with matters which are particular to that package
9561 or require more complicated processing than that
9562 provided by <prgn>dpkg</prgn>. Details of when and
9563 how they are called are in <ref id="maintainerscripts">.
9567 It is very important to make these scripts idempotent.
9568 See <ref id="idempotency">.
9572 The maintainer scripts are not guaranteed to run with a
9573 controlling terminal and may not be able to interact with
9574 the user. See <ref id="controllingterminal">.
9578 <tag><tt>conffiles</tt>
9581 This file contains a list of configuration files which
9582 are to be handled automatically by <prgn>dpkg</prgn>
9583 (see <ref id="pkg-conffiles">). Note that not necessarily
9584 every configuration file should be listed here.
9587 <tag><tt>shlibs</tt>
9590 This file contains a list of the shared libraries
9591 supplied by the package, with dependency details for
9592 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9593 when it determines what dependencies are required in a
9594 package control file. The <tt>shlibs</tt> file format
9595 is described on <ref id="shlibs">.
9600 <sect id="pkg-controlfile">
9601 <heading>The main control information file: <tt>control</tt></heading>
9604 The most important control information file used by
9605 <prgn>dpkg</prgn> when it installs a package is
9606 <tt>control</tt>. It contains all the package's "vital
9611 The binary package control files of packages built from
9612 Debian sources are made by a special tool,
9613 <prgn>dpkg-gencontrol</prgn>, which reads
9614 <file>debian/control</file> and <file>debian/changelog</file> to
9615 find the information it needs. See <ref id="pkg-sourcepkg"> for
9620 The fields in binary package control files are listed in
9621 <ref id="binarycontrolfiles">.
9625 A description of the syntax of control files and the purpose
9626 of the fields is available in <ref id="controlfields">.
9631 <heading>Time Stamps</heading>
9634 See <ref id="timestamps">.
9639 <appendix id="pkg-sourcepkg">
9640 <heading>Source packages (from old Packaging Manual) </heading>
9643 The Debian binary packages in the distribution are generated
9644 from Debian sources, which are in a special format to assist
9645 the easy and automatic building of binaries.
9648 <sect id="pkg-sourcetools">
9649 <heading>Tools for processing source packages</heading>
9652 Various tools are provided for manipulating source packages;
9653 they pack and unpack sources and help build of binary
9654 packages and help manage the distribution of new versions.
9658 They are introduced and typical uses described here; see
9659 <manref name="dpkg-source" section="1"> for full
9660 documentation about their arguments and operation.
9664 For examples of how to construct a Debian source package,
9665 and how to use those utilities that are used by Debian
9666 source packages, please see the <prgn>hello</prgn> example
9670 <sect1 id="pkg-dpkg-source">
9672 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
9677 This program is frequently used by hand, and is also
9678 called from package-independent automated building scripts
9679 such as <prgn>dpkg-buildpackage</prgn>.
9683 To unpack a package it is typically invoked with
9685 dpkg-source -x <var>.../path/to/filename</var>.dsc
9690 with the <file><var>filename</var>.tar.gz</file> and
9691 <file><var>filename</var>.diff.gz</file> (if applicable) in
9692 the same directory. It unpacks into
9693 <file><var>package</var>-<var>version</var></file>, and if
9695 <file><var>package</var>-<var>version</var>.orig</file>, in
9696 the current directory.
9700 To create a packed source archive it is typically invoked:
9702 dpkg-source -b <var>package</var>-<var>version</var>
9707 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
9708 <file>.diff.gz</file> (if appropriate) in the current
9709 directory. <prgn>dpkg-source</prgn> does not clean the
9710 source tree first - this must be done separately if it is
9715 See also <ref id="pkg-sourcearchives">.</p>
9719 <sect1 id="pkg-dpkg-buildpackage">
9721 <prgn>dpkg-buildpackage</prgn> - overall package-building
9726 <prgn>dpkg-buildpackage</prgn> is a script which invokes
9727 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
9728 targets <tt>clean</tt>, <tt>build</tt> and
9729 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
9730 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
9731 source and binary package upload.
9735 It is usually invoked by hand from the top level of the
9736 built or unbuilt source directory. It may be invoked with
9737 no arguments; useful arguments include:
9738 <taglist compact="compact">
9739 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
9742 Do not sign the <tt>.changes</tt> file or the
9743 source package <tt>.dsc</tt> file, respectively.</p>
9745 <tag><tt>-p<var>sign-command</var></tt></tag>
9748 Invoke <var>sign-command</var> instead of finding
9749 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
9750 <var>sign-command</var> must behave just like
9751 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9753 <tag><tt>-r<var>root-command</var></tt></tag>
9756 When root privilege is required, invoke the command
9757 <var>root-command</var>. <var>root-command</var>
9758 should invoke its first argument as a command, from
9759 the <prgn>PATH</prgn> if necessary, and pass its
9760 second and subsequent arguments to the command it
9761 calls. If no <var>root-command</var> is supplied
9762 then <var>dpkg-buildpackage</var> will take no
9763 special action to gain root privilege, so that for
9764 most packages it will have to be invoked as root to
9767 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9770 Two types of binary-only build and upload - see
9771 <manref name="dpkg-source" section="1">.
9778 <sect1 id="pkg-dpkg-gencontrol">
9780 <prgn>dpkg-gencontrol</prgn> - generates binary package
9785 This program is usually called from <file>debian/rules</file>
9786 (see <ref id="pkg-sourcetree">) in the top level of the source
9791 This is usually done just before the files and directories in the
9792 temporary directory tree where the package is being built have their
9793 permissions and ownerships set and the package is constructed using
9794 <prgn>dpkg-deb/</prgn>
9796 This is so that the control file which is produced has
9797 the right permissions
9802 <prgn>dpkg-gencontrol</prgn> must be called after all the
9803 files which are to go into the package have been placed in
9804 the temporary build directory, so that its calculation of
9805 the installed size of a package is correct.
9809 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9810 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9811 variable substitutions created by
9812 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9817 For a package which generates only one binary package, and
9818 which builds it in <file>debian/tmp</file> relative to the top
9819 of the source package, it is usually sufficient to call
9820 <prgn>dpkg-gencontrol</prgn>.
9824 Sources which build several binaries will typically need
9827 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9828 </example> The <tt>-P</tt> tells
9829 <prgn>dpkg-gencontrol</prgn> that the package is being
9830 built in a non-default directory, and the <tt>-p</tt>
9831 tells it which package's control file should be generated.
9835 <prgn>dpkg-gencontrol</prgn> also adds information to the
9836 list of files in <file>debian/files</file>, for the benefit of
9837 (for example) a future invocation of
9838 <prgn>dpkg-genchanges</prgn>.</p>
9841 <sect1 id="pkg-dpkg-shlibdeps">
9843 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9848 This program is usually called from <file>debian/rules</file>
9849 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9850 id="pkg-sourcetree">), in the top level of the source tree.
9854 Its arguments are executables and shared libraries
9857 They may be specified either in the locations in the
9858 source tree where they are created or in the locations
9859 in the temporary build tree where they are installed
9860 prior to binary package creation.
9862 </footnote> for which shared library dependencies should
9863 be included in the binary package's control file.
9867 If some of the found shared libraries should only
9868 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9869 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9870 by using the <tt>-d<var>dependency-field</var></tt> option
9871 before those executable(s). (Each <tt>-d</tt> option
9872 takes effect until the next <tt>-d</tt>.)
9876 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9877 output control file to be modified. Instead by default it
9878 adds to the <file>debian/substvars</file> file variable
9879 settings like <tt>shlibs:Depends</tt>. These variable
9880 settings must be referenced in dependency fields in the
9881 appropriate per-binary-package sections of the source
9886 For example, a package that generates an essential part
9887 which requires dependencies, and optional parts that
9888 which only require a recommendation, would separate those
9889 two sets of dependencies into two different fields.<footnote>
9890 At the time of writing, an example for this was the
9891 <package/xmms/ package, with Depends used for the xmms
9892 executable, Recommends for the plug-ins and Suggests for
9893 even more optional features provided by unzip.
9895 It can say in its <file>debian/rules</file>:
9897 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9898 -dRecommends <var>optionalpart anotheroptionalpart</var>
9900 and then in its main control file <file>debian/control</file>:
9903 Depends: ${shlibs:Depends}
9904 Recommends: ${shlibs:Recommends}
9910 Sources which produce several binary packages with
9911 different shared library dependency requirements can use
9912 the <tt>-p<var>varnameprefix</var></tt> option to override
9913 the default <tt>shlibs:</tt> prefix (one invocation of
9914 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9915 They can thus produce several sets of dependency
9916 variables, each of the form
9917 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9918 which can be referred to in the appropriate parts of the
9919 binary package control files.
9924 <sect1 id="pkg-dpkg-distaddfile">
9926 <prgn>dpkg-distaddfile</prgn> - adds a file to
9927 <file>debian/files</file>
9931 Some packages' uploads need to include files other than
9932 the source and binary package files.
9936 <prgn>dpkg-distaddfile</prgn> adds a file to the
9937 <file>debian/files</file> file so that it will be included in
9938 the <file>.changes</file> file when
9939 <prgn>dpkg-genchanges</prgn> is run.
9943 It is usually invoked from the <tt>binary</tt> target of
9944 <file>debian/rules</file>:
9946 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9948 The <var>filename</var> is relative to the directory where
9949 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9950 is usually the directory above the top level of the source
9951 tree. The <file>debian/rules</file> target should put the
9952 file there just before or just after calling
9953 <prgn>dpkg-distaddfile</prgn>.
9957 The <var>section</var> and <var>priority</var> are passed
9958 unchanged into the resulting <file>.changes</file> file.
9963 <sect1 id="pkg-dpkg-genchanges">
9965 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9970 This program is usually called by package-independent
9971 automatic building scripts such as
9972 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9977 It is usually called in the top level of a built source
9978 tree, and when invoked with no arguments will print out a
9979 straightforward <file>.changes</file> file based on the
9980 information in the source package's changelog and control
9981 file and the binary and source packages which should have
9987 <sect1 id="pkg-dpkg-parsechangelog">
9989 <prgn>dpkg-parsechangelog</prgn> - produces parsed
9990 representation of a changelog
9994 This program is used internally by
9995 <prgn>dpkg-source</prgn> et al. It may also occasionally
9996 be useful in <file>debian/rules</file> and elsewhere. It
9997 parses a changelog, <file>debian/changelog</file> by default,
9998 and prints a control-file format representation of the
9999 information in it to standard output.
10003 <sect1 id="pkg-dpkg-architecture">
10005 <prgn>dpkg-architecture</prgn> - information about the build and
10010 This program can be used manually, but is also invoked by
10011 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
10012 environment or make variables which specify the build and host
10013 architecture for the package building process.
10018 <sect id="pkg-sourcetree">
10019 <heading>The Debianised source tree</heading>
10022 The source archive scheme described later is intended to
10023 allow a Debianised source tree with some associated control
10024 information to be reproduced and transported easily. The
10025 Debianised source tree is a version of the original program
10026 with certain files added for the benefit of the
10027 Debianisation process, and with any other changes required
10028 made to the rest of the source code and installation
10033 The extra files created for Debian are in the subdirectory
10034 <file>debian</file> of the top level of the Debianised source
10035 tree. They are described below.
10038 <sect1 id="pkg-debianrules">
10039 <heading><file>debian/rules</file> - the main building script</heading>
10042 See <ref id="debianrules">.
10046 <sect1 id="pkg-srcsubstvars">
10047 <heading><file>debian/substvars</file> and variable substitutions</heading>
10050 See <ref id="substvars">.
10056 <heading><file>debian/files</file></heading>
10059 See <ref id="debianfiles">.
10063 <sect1><heading><file>debian/tmp</file>
10067 This is the canonical temporary location for the
10068 construction of binary packages by the <tt>binary</tt>
10069 target. The directory <file>tmp</file> serves as the root of
10070 the file system tree as it is being constructed (for
10071 example, by using the package's upstream makefiles install
10072 targets and redirecting the output there), and it also
10073 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10074 id="pkg-bincreating">.
10078 If several binary packages are generated from the same
10079 source tree it is usual to use several
10080 <file>debian/tmp<var>something</var></file> directories, for
10081 example <file>tmp-a</file> or <file>tmp-doc</file>.
10085 Whatever <file>tmp</file> directories are created and used by
10086 <tt>binary</tt> must of course be removed by the
10087 <tt>clean</tt> target.</p></sect1>
10091 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10095 As it exists on the FTP site, a Debian source package
10096 consists of three related files. You must have the right
10097 versions of all three to be able to use them.
10102 <tag>Debian source control file - <tt>.dsc</tt></tag>
10104 This file is a control file used by <prgn>dpkg-source</prgn>
10105 to extract a source package.
10106 See <ref id="debiansourcecontrolfiles">.
10110 Original source archive -
10112 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10118 This is a compressed (with <tt>gzip -9</tt>)
10119 <prgn>tar</prgn> file containing the source code from
10120 the upstream authors of the program.
10125 Debianisation diff -
10127 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10133 This is a unified context diff (<tt>diff -u</tt>)
10134 giving the changes which are required to turn the
10135 original source into the Debian source. These changes
10136 may only include editing and creating plain files.
10137 The permissions of files, the targets of symbolic
10138 links and the characteristics of special files or
10139 pipes may not be changed and no files may be removed
10144 All the directories in the diff must exist, except the
10145 <file>debian</file> subdirectory of the top of the source
10146 tree, which will be created by
10147 <prgn>dpkg-source</prgn> if necessary when unpacking.
10151 The <prgn>dpkg-source</prgn> program will
10152 automatically make the <file>debian/rules</file> file
10153 executable (see below).</p></item>
10158 If there is no original source code - for example, if the
10159 package is specially prepared for Debian or the Debian
10160 maintainer is the same as the upstream maintainer - the
10161 format is slightly different: then there is no diff, and the
10163 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10164 and preferably contains a directory named
10165 <file><var>package</var>-<var>version</var></file>.
10170 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10173 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10174 Debian source package. However, if it is not available it
10175 is possible to unpack a Debian source archive as follows:
10176 <enumlist compact="compact">
10179 Untar the tarfile, which will create a <file>.orig</file>
10183 <p>Rename the <file>.orig</file> directory to
10184 <file><var>package</var>-<var>version</var></file>.</p>
10188 Create the subdirectory <file>debian</file> at the top of
10189 the source tree.</p>
10191 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10193 <item><p>Untar the tarfile again if you want a copy of the original
10194 source code alongside the Debianised version.</p>
10199 It is not possible to generate a valid Debian source archive
10200 without using <prgn>dpkg-source</prgn>. In particular,
10201 attempting to use <prgn>diff</prgn> directly to generate the
10202 <file>.diff.gz</file> file will not work.
10206 <heading>Restrictions on objects in source packages</heading>
10209 The source package may not contain any hard links
10211 This is not currently detected when building source
10212 packages, but only when extracting
10216 Hard links may be permitted at some point in the
10217 future, but would require a fair amount of
10219 </footnote>, device special files, sockets or setuid or
10222 Setgid directories are allowed.
10227 The source packaging tools manage the changes between the
10228 original and Debianised source using <prgn>diff</prgn> and
10229 <prgn>patch</prgn>. Turning the original source tree as
10230 included in the <file>.orig.tar.gz</file> into the debianised
10231 source must not involve any changes which cannot be
10232 handled by these tools. Problematic changes which cause
10233 <prgn>dpkg-source</prgn> to halt with an error when
10234 building the source package are:
10235 <list compact="compact">
10236 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10238 <item><p>Changing the targets of symbolic links.</p>
10240 <item><p>Creating directories, other than <file>debian</file>.</p>
10242 <item><p>Changes to the contents of binary files.</p></item>
10243 </list> Changes which cause <prgn>dpkg-source</prgn> to
10244 print a warning but continue anyway are:
10245 <list compact="compact">
10248 Removing files, directories or symlinks.
10250 Renaming a file is not treated specially - it is
10251 seen as the removal of the old file (which
10252 generates a warning, but is otherwise ignored),
10253 and the creation of the new one.
10259 Changed text files which are missing the usual final
10260 newline (either in the original or the modified
10265 Changes which are not represented, but which are not detected by
10266 <prgn>dpkg-source</prgn>, are:
10267 <list compact="compact">
10268 <item><p>Changing the permissions of files (other than
10269 <file>debian/rules</file>) and directories.</p></item>
10274 The <file>debian</file> directory and <file>debian/rules</file>
10275 are handled specially by <prgn>dpkg-source</prgn> - before
10276 applying the changes it will create the <file>debian</file>
10277 directory, and afterwards it will make
10278 <file>debian/rules</file> world-executable.
10284 <appendix id="pkg-controlfields">
10285 <heading>Control files and their fields (from old Packaging Manual)</heading>
10288 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10289 data in a common format, known as control files. Binary and
10290 source packages have control data as do the <file>.changes</file>
10291 files which control the installation of uploaded files, and
10292 <prgn>dpkg</prgn>'s internal databases are in a similar
10297 <heading>Syntax of control files</heading>
10300 See <ref id="controlsyntax">.
10304 It is important to note that there are several fields which
10305 are optional as far as <prgn>dpkg</prgn> and the related
10306 tools are concerned, but which must appear in every Debian
10307 package, or whose omission may cause problems.
10312 <heading>List of fields</heading>
10315 See <ref id="controlfieldslist">.
10319 This section now contains only the fields that didn't belong
10320 to the Policy manual.
10323 <sect1 id="pkg-f-Filename">
10324 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10327 These fields in <tt>Packages</tt> files give the
10328 filename(s) of (the parts of) a package in the
10329 distribution directories, relative to the root of the
10330 Debian hierarchy. If the package has been split into
10331 several parts the parts are all listed in order, separated
10336 <sect1 id="pkg-f-Size">
10337 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10340 These fields in <file>Packages</file> files give the size (in
10341 bytes, expressed in decimal) and MD5 checksum of the
10342 file(s) which make(s) up a binary package in the
10343 distribution. If the package is split into several parts
10344 the values for the parts are listed in order, separated by
10349 <sect1 id="pkg-f-Status">
10350 <heading><tt>Status</tt></heading>
10353 This field in <prgn>dpkg</prgn>'s status file records
10354 whether the user wants a package installed, removed or
10355 left alone, whether it is broken (requiring
10356 re-installation) or not and what its current state on the
10357 system is. Each of these pieces of information is a
10362 <sect1 id="pkg-f-Config-Version">
10363 <heading><tt>Config-Version</tt></heading>
10366 If a package is not installed or not configured, this
10367 field in <prgn>dpkg</prgn>'s status file records the last
10368 version of the package which was successfully
10373 <sect1 id="pkg-f-Conffiles">
10374 <heading><tt>Conffiles</tt></heading>
10377 This field in <prgn>dpkg</prgn>'s status file contains
10378 information about the automatically-managed configuration
10379 files held by a package. This field should <em>not</em>
10380 appear anywhere in a package!
10385 <heading>Obsolete fields</heading>
10388 These are still recognized by <prgn>dpkg</prgn> but should
10389 not appear anywhere any more.
10391 <taglist compact="compact">
10393 <tag><tt>Revision</tt></tag>
10394 <tag><tt>Package-Revision</tt></tag>
10395 <tag><tt>Package_Revision</tt></tag>
10397 The Debian revision part of the package version was
10398 at one point in a separate control file field. This
10399 field went through several names.
10402 <tag><tt>Recommended</tt></tag>
10403 <item>Old name for <tt>Recommends</tt>.</item>
10405 <tag><tt>Optional</tt></tag>
10406 <item>Old name for <tt>Suggests</tt>.</item>
10408 <tag><tt>Class</tt></tag>
10409 <item>Old name for <tt>Priority</tt>.</item>
10418 <appendix id="pkg-conffiles">
10419 <heading>Configuration file handling (from old Packaging Manual)</heading>
10422 <prgn>dpkg</prgn> can do a certain amount of automatic
10423 handling of package configuration files.
10427 Whether this mechanism is appropriate depends on a number of
10428 factors, but basically there are two approaches to any
10429 particular configuration file.
10433 The easy method is to ship a best-effort configuration in the
10434 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10435 handle updates. If the user is unlikely to want to edit the
10436 file, but you need them to be able to without losing their
10437 changes, and a new package with a changed version of the file
10438 is only released infrequently, this is a good approach.
10442 The hard method is to build the configuration file from
10443 scratch in the <prgn>postinst</prgn> script, and to take the
10444 responsibility for fixing any mistakes made in earlier
10445 versions of the package automatically. This will be
10446 appropriate if the file is likely to need to be different on
10450 <sect><heading>Automatic handling of configuration files by
10455 A package may contain a control area file called
10456 <tt>conffiles</tt>. This file should be a list of filenames
10457 of configuration files needing automatic handling, separated
10458 by newlines. The filenames should be absolute pathnames,
10459 and the files referred to should actually exist in the
10464 When a package is upgraded <prgn>dpkg</prgn> will process
10465 the configuration files during the configuration stage,
10466 shortly before it runs the package's <prgn>postinst</prgn>
10471 For each file it checks to see whether the version of the
10472 file included in the package is the same as the one that was
10473 included in the last version of the package (the one that is
10474 being upgraded from); it also compares the version currently
10475 installed on the system with the one shipped with the last
10480 If neither the user nor the package maintainer has changed
10481 the file, it is left alone. If one or the other has changed
10482 their version, then the changed version is preferred - i.e.,
10483 if the user edits their file, but the package maintainer
10484 doesn't ship a different version, the user's changes will
10485 stay, silently, but if the maintainer ships a new version
10486 and the user hasn't edited it the new version will be
10487 installed (with an informative message). If both have
10488 changed their version the user is prompted about the problem
10489 and must resolve the differences themselves.
10493 The comparisons are done by calculating the MD5 message
10494 digests of the files, and storing the MD5 of the file as it
10495 was included in the most recent version of the package.
10499 When a package is installed for the first time
10500 <prgn>dpkg</prgn> will install the file that comes with it,
10501 unless that would mean overwriting a file already on the
10506 However, note that <prgn>dpkg</prgn> will <em>not</em>
10507 replace a conffile that was removed by the user (or by a
10508 script). This is necessary because with some programs a
10509 missing file produces an effect hard or impossible to
10510 achieve in another way, so that a missing file needs to be
10511 kept that way if the user did it.
10515 Note that a package should <em>not</em> modify a
10516 <prgn>dpkg</prgn>-handled conffile in its maintainer
10517 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10518 the user confusing and possibly dangerous options for
10519 conffile update when the package is upgraded.</p>
10522 <sect><heading>Fully-featured maintainer script configuration
10527 For files which contain site-specific information such as
10528 the hostname and networking details and so forth, it is
10529 better to create the file in the package's
10530 <prgn>postinst</prgn> script.
10534 This will typically involve examining the state of the rest
10535 of the system to determine values and other information, and
10536 may involve prompting the user for some information which
10537 can't be obtained some other way.
10541 When using this method there are a couple of important
10542 issues which should be considered:
10546 If you discover a bug in the program which generates the
10547 configuration file, or if the format of the file changes
10548 from one version to the next, you will have to arrange for
10549 the postinst script to do something sensible - usually this
10550 will mean editing the installed configuration file to remove
10551 the problem or change the syntax. You will have to do this
10552 very carefully, since the user may have changed the file,
10553 perhaps to fix the very problem that your script is trying
10554 to deal with - you will have to detect these situations and
10555 deal with them correctly.
10559 If you do go down this route it's probably a good idea to
10560 make the program that generates the configuration file(s) a
10561 separate program in <file>/usr/sbin</file>, by convention called
10562 <file><var>package</var>config</file> and then run that if
10563 appropriate from the post-installation script. The
10564 <tt><var>package</var>config</tt> program should not
10565 unquestioningly overwrite an existing configuration - if its
10566 mode of operation is geared towards setting up a package for
10567 the first time (rather than any arbitrary reconfiguration
10568 later) you should have it check whether the configuration
10569 already exists, and require a <tt>--force</tt> flag to
10570 overwrite it.</p></sect>
10573 <appendix id="pkg-alternatives"><heading>Alternative versions of
10574 an interface - <prgn>update-alternatives</prgn> (from old
10579 When several packages all provide different versions of the
10580 same program or file it is useful to have the system select a
10581 default, but to allow the system administrator to change it
10582 and have their decisions respected.
10586 For example, there are several versions of the <prgn>vi</prgn>
10587 editor, and there is no reason to prevent all of them from
10588 being installed at once, each under their own name
10589 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10590 Nevertheless it is desirable to have the name <tt>vi</tt>
10591 refer to something, at least by default.
10595 If all the packages involved cooperate, this can be done with
10596 <prgn>update-alternatives</prgn>.
10600 Each package provides its own version under its own name, and
10601 calls <prgn>update-alternatives</prgn> in its postinst to
10602 register its version (and again in its prerm to deregister
10607 See the man page <manref name="update-alternatives"
10608 section="8"> for details.
10612 If <prgn>update-alternatives</prgn> does not seem appropriate
10613 you may wish to consider using diversions instead.</p>
10616 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10617 package's version of a file (from old Packaging Manual)
10621 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10622 when it reinstalls the package it belongs to, and to have it
10623 put the file from the package somewhere else instead.
10627 This can be used locally to override a package's version of a
10628 file, or by one package to override another's version (or
10629 provide a wrapper for it).
10633 Before deciding to use a diversion, read <ref
10634 id="pkg-alternatives"> to see if you really want a diversion
10635 rather than several alternative versions of a program.
10639 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10640 and updated by a special program <prgn>dpkg-divert</prgn>.
10641 Please see <manref name="dpkg-divert" section="8"> for full
10642 details of its operation.
10646 When a package wishes to divert a file from another, it should
10647 call <prgn>dpkg-divert</prgn> in its preinst to add the
10648 diversion and rename the existing file. For example,
10649 supposing that a <prgn>smailwrapper</prgn> package wishes to
10650 install a wrapper around <file>/usr/sbin/smail</file>:
10652 dpkg-divert --package smailwrapper --add --rename \
10653 --divert /usr/sbin/smail.real /usr/sbin/smail
10654 </example> The <tt>--package smailwrapper</tt> ensures that
10655 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
10656 can bypass the diversion and get installed as the true version.
10657 It's safe to add the diversion unconditionally on upgrades since
10658 it will be left unchanged if it already exists, but
10659 <prgn>dpkg-divert</prgn> will display a message. To suppress that
10660 message, make the command conditional on the version from which
10661 the package is being upgraded:
10663 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
10664 dpkg-divert --package smailwrapper --add --rename \
10665 --divert /usr/sbin/smail.real /usr/sbin/smail
10667 </example> where <tt>1.0-2</tt> is the version at which the
10668 diversion was first added to the package. Running the command
10669 during abort-upgrade is pointless but harmless.
10673 The postrm has to do the reverse:
10675 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
10676 dpkg-divert --package smailwrapper --remove --rename \
10677 --divert /usr/sbin/smail.real /usr/sbin/smail
10679 </example> If the diversion was added at a particular version, the
10680 postrm should also handle the failure case of upgrading from an
10681 older version (unless the older version is so old that direct
10682 upgrades are no longer supported):
10684 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
10685 dpkg-divert --package smailwrapper --remove --rename \
10686 --divert /usr/sbin/smail.real /usr/sbin/smail
10688 </example> where <tt>1.02-2</tt> is the version at which the
10689 diversion was first added to the package. The postrm should not
10690 remove the diversion on upgrades both because there's no reason to
10691 remove the diversion only to immediately re-add it and since the
10692 postrm of the old package is run after unpacking so the removal of
10693 the diversion will fail.
10697 Do not attempt to divert a file which is vitally important for
10698 the system's operation - when using <prgn>dpkg-divert</prgn>
10699 there is a time, after it has been diverted but before
10700 <prgn>dpkg</prgn> has installed the new version, when the file
10701 does not exist.</p>
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