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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 (the author of this manual has heard of a
3067 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
3068 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
3069 <tt>2</tt> and so forth).
3073 <sect1 id="f-Description">
3074 <heading><tt>Description</tt></heading>
3077 In a source or binary control file, the <tt>Description</tt>
3078 field contains a description of the binary package, consisting
3079 of two parts, the synopsis or the short description, and the
3080 long description. The field's format is as follows:
3085 Description: <single line synopsis>
3086 <extended description over several lines>
3091 The lines in the extended description can have these formats:
3097 Those starting with a single space are part of a paragraph.
3098 Successive lines of this form will be word-wrapped when
3099 displayed. The leading space will usually be stripped off.
3103 Those starting with two or more spaces. These will be
3104 displayed verbatim. If the display cannot be panned
3105 horizontally, the displaying program will line wrap them "hard"
3106 (i.e., without taking account of word breaks). If it can they
3107 will be allowed to trail off to the right. None, one or two
3108 initial spaces may be deleted, but the number of spaces
3109 deleted from each line will be the same (so that you can have
3110 indenting work correctly, for example).
3114 Those containing a single space followed by a single full stop
3115 character. These are rendered as blank lines. This is the
3116 <em>only</em> way to get a blank line<footnote>
3117 Completely empty lines will not be rendered as blank lines.
3118 Instead, they will cause the parser to think you're starting
3119 a whole new record in the control file, and will therefore
3120 likely abort with an error.
3125 Those containing a space, a full stop and some more characters.
3126 These are for future expansion. Do not use them.
3132 Do not use tab characters. Their effect is not predictable.
3136 See <ref id="descriptions"> for further information on this.
3140 In a <file>.changes</file> file, the <tt>Description</tt>
3141 field contains a summary of the descriptions for the packages
3142 being uploaded. For this case, the first line of the field
3143 value (the part on the same line as <tt>Description:</tt>) is
3144 always empty. The content of the field is expressed as
3145 continuation lines, one line per package. Each line is
3146 indented by one space and contains the name of a binary
3147 package, a space, a hyphen (<tt>-</tt>), a space, and the
3148 short description line from that package.
3152 <sect1 id="f-Distribution">
3153 <heading><tt>Distribution</tt></heading>
3156 In a <file>.changes</file> file or parsed changelog output
3157 this contains the (space-separated) name(s) of the
3158 distribution(s) where this version of the package should
3159 be installed. Valid distributions are determined by the
3160 archive maintainers.<footnote>
3161 Example distribution names in the Debian archive used in
3162 <file>.changes</file> files are:
3163 <taglist compact="compact">
3164 <tag><em>unstable</em></tag>
3166 This distribution value refers to the
3167 <em>developmental</em> part of the Debian distribution
3168 tree. Most new packages, new upstream versions of
3169 packages and bug fixes go into the <em>unstable</em>
3173 <tag><em>experimental</em></tag>
3175 The packages with this distribution value are deemed
3176 by their maintainers to be high risk. Oftentimes they
3177 represent early beta or developmental packages from
3178 various sources that the maintainers want people to
3179 try, but are not ready to be a part of the other parts
3180 of the Debian distribution tree.
3185 Others are used for updating stable releases or for
3186 security uploads. More information is available in the
3187 Debian Developer's Reference, section "The Debian
3191 The Debian archive software only supports listing a single
3192 distribution. Migration of packages to other distributions is
3193 handled outside of the upload process.
3198 <heading><tt>Date</tt></heading>
3201 This field includes the date the package was built or last edited.
3205 The value of this field is usually extracted from the
3206 <file>debian/changelog</file> file - see
3207 <ref id="dpkgchangelog">).
3211 <sect1 id="f-Format">
3212 <heading><tt>Format</tt></heading>
3215 This field specifies a format revision for the file.
3216 The most current format described in the Policy Manual
3217 is version <strong>1.5</strong>. The syntax of the
3218 format value is the same as that of a package version
3219 number except that no epoch or Debian revision is allowed
3220 - see <ref id="f-Version">.
3224 <sect1 id="f-Urgency">
3225 <heading><tt>Urgency</tt></heading>
3228 This is a description of how important it is to upgrade to
3229 this version from previous ones. It consists of a single
3230 keyword taking one of the values <tt>low</tt>,
3231 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3232 <tt>critical</tt><footnote>
3233 Other urgency values are supported with configuration
3234 changes in the archive software but are not used in Debian.
3235 The urgency affects how quickly a package will be considered
3236 for inclusion into the <tt>testing</tt> distribution and
3237 gives an indication of the importance of any fixes included
3238 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3239 treated as synonymous.
3240 </footnote> (not case-sensitive) followed by an optional
3241 commentary (separated by a space) which is usually in
3242 parentheses. For example:
3245 Urgency: low (HIGH for users of diversions)
3251 The value of this field is usually extracted from the
3252 <file>debian/changelog</file> file - see
3253 <ref id="dpkgchangelog">.
3257 <sect1 id="f-Changes">
3258 <heading><tt>Changes</tt></heading>
3261 This field contains the human-readable changes data, describing
3262 the differences between the last version and the current one.
3266 The first line of the field value (the part on the same line
3267 as <tt>Changes:</tt>) is always empty. The content of the
3268 field is expressed as continuation lines, with each line
3269 indented by at least one space. Blank lines must be
3270 represented by a line consisting only of a space and a full
3275 The value of this field is usually extracted from the
3276 <file>debian/changelog</file> file - see
3277 <ref id="dpkgchangelog">).
3281 Each version's change information should be preceded by a
3282 "title" line giving at least the version, distribution(s)
3283 and urgency, in a human-readable way.
3287 If data from several versions is being returned the entry
3288 for the most recent version should be returned first, and
3289 entries should be separated by the representation of a
3290 blank line (the "title" line may also be followed by the
3291 representation of a blank line).
3295 <sect1 id="f-Binary">
3296 <heading><tt>Binary</tt></heading>
3299 This field is a list of binary packages. Its syntax and
3300 meaning varies depending on the control file in which it
3305 When it appears in the <file>.dsc</file> file, it lists binary
3306 packages which a source package can produce, separated by
3308 A space after each comma is conventional.
3309 </footnote>. It may span multiple lines. The source package
3310 does not necessarily produce all of these binary packages for
3311 every architecture. The source control file doesn't contain
3312 details of which architectures are appropriate for which of
3313 the binary packages.
3317 When it appears in a <file>.changes</file> file, it lists the
3318 names of the binary packages being uploaded, separated by
3319 whitespace (not commas). It may span multiple lines.
3323 <sect1 id="f-Installed-Size">
3324 <heading><tt>Installed-Size</tt></heading>
3327 This field appears in the control files of binary packages,
3328 and in the <file>Packages</file> files. It gives an estimate
3329 of the total amount of disk space required to install the
3330 named package. Actual installed size may vary based on block
3331 size, file system properties, or actions taken by package
3336 The disk space is given as the integer value of the estimated
3337 installed size in bytes, divided by 1024 and rounded up.
3341 <sect1 id="f-Files">
3342 <heading><tt>Files</tt></heading>
3345 This field contains a list of files with information about
3346 each one. The exact information and syntax varies with
3351 In all cases, Files is a multiline field. The first line of
3352 the field value (the part on the same line as <tt>Files:</tt>)
3353 is always empty. The content of the field is expressed as
3354 continuation lines, one line per file. Each line must be
3355 indented by one space and contain a number of sub-fields,
3356 separated by spaces, as described below.
3360 In the <file>.dsc</file> file, each line contains the MD5
3361 checksum, size and filename of the tar file and (if
3362 applicable) diff file which make up the remainder of the
3363 source package<footnote>
3364 That is, the parts which are not the <tt>.dsc</tt>.
3365 </footnote>. For example:
3368 c6f698f19f2a2aa07dbb9bbda90a2754 571925 example_1.2.orig.tar.gz
3369 938512f08422f3509ff36f125f5873ba 6220 example_1.2-1.diff.gz
3371 The exact forms of the filenames are described
3372 in <ref id="pkg-sourcearchives">.
3376 In the <file>.changes</file> file this contains one line per
3377 file being uploaded. Each line contains the MD5 checksum,
3378 size, section and priority and the filename. For example:
3381 4c31ab7bfc40d3cf49d7811987390357 1428 text extra example_1.2-1.dsc
3382 c6f698f19f2a2aa07dbb9bbda90a2754 571925 text extra example_1.2.orig.tar.gz
3383 938512f08422f3509ff36f125f5873ba 6220 text extra example_1.2-1.diff.gz
3384 7c98fe853b3bbb47a00e5cd129b6cb56 703542 text extra example_1.2-1_i386.deb
3386 The <qref id="f-Section">section</qref>
3387 and <qref id="f-Priority">priority</qref> are the values of
3388 the corresponding fields in the main source control file. If
3389 no section or priority is specified then <tt>-</tt> should be
3390 used, though section and priority values must be specified for
3391 new packages to be installed properly.
3395 The special value <tt>byhand</tt> for the section in a
3396 <tt>.changes</tt> file indicates that the file in question
3397 is not an ordinary package file and must by installed by
3398 hand by the distribution maintainers. If the section is
3399 <tt>byhand</tt> the priority should be <tt>-</tt>.
3403 If a new Debian revision of a package is being shipped and
3404 no new original source archive is being distributed the
3405 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3406 entry for the original source archive
3407 <file><var>package</var>_<var>upstream-version</var>.orig.tar.gz</file>,
3408 but the <file>.changes</file> file should leave it out. In
3409 this case the original source archive on the distribution
3410 site must match exactly, byte-for-byte, the original
3411 source archive which was used to generate the
3412 <file>.dsc</file> file and diff which are being uploaded.</p>
3415 <sect1 id="f-Closes">
3416 <heading><tt>Closes</tt></heading>
3419 A space-separated list of bug report numbers that the upload
3420 governed by the .changes file closes.
3424 <sect1 id="f-Homepage">
3425 <heading><tt>Homepage</tt></heading>
3428 The URL of the web site for this package, preferably (when
3429 applicable) the site from which the original source can be
3430 obtained and any additional upstream documentation or
3431 information may be found. The content of this field is a
3432 simple URL without any surrounding characters such as
3440 <heading>User-defined fields</heading>
3443 Additional user-defined fields may be added to the
3444 source package control file. Such fields will be
3445 ignored, and not copied to (for example) binary or
3446 source package control files or upload control files.
3450 If you wish to add additional unsupported fields to
3451 these output files you should use the mechanism
3456 Fields in the main source control information file with
3457 names starting <tt>X</tt>, followed by one or more of
3458 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3459 be copied to the output files. Only the part of the
3460 field name after the hyphen will be used in the output
3461 file. Where the letter <tt>B</tt> is used the field
3462 will appear in binary package control files, where the
3463 letter <tt>S</tt> is used in source package control
3464 files and where <tt>C</tt> is used in upload control
3465 (<tt>.changes</tt>) files.
3469 For example, if the main source information control file
3472 XBS-Comment: I stand between the candle and the star.
3474 then the binary and source package control files will contain the
3477 Comment: I stand between the candle and the star.
3486 <chapt id="maintainerscripts">
3487 <heading>Package maintainer scripts and installation procedure</heading>
3490 <heading>Introduction to package maintainer scripts</heading>
3493 It is possible to supply scripts as part of a package which
3494 the package management system will run for you when your
3495 package is installed, upgraded or removed.
3499 These scripts are the files <prgn>preinst</prgn>,
3500 <prgn>postinst</prgn>, <prgn>prerm</prgn> and
3501 <prgn>postrm</prgn> in the control area of the package.
3502 They must be proper executable files; if they are scripts
3503 (which is recommended), they must start with the usual
3504 <tt>#!</tt> convention. They should be readable and
3505 executable by anyone, and must not be world-writable.
3509 The package management system looks at the exit status from
3510 these scripts. It is important that they exit with a
3511 non-zero status if there is an error, so that the package
3512 management system can stop its processing. For shell
3513 scripts this means that you <em>almost always</em> need to
3514 use <tt>set -e</tt> (this is usually true when writing shell
3515 scripts, in fact). It is also important, of course, that
3516 they exit with a zero status if everything went well.
3520 Additionally, packages interacting with users using
3521 <tt>debconf</tt> in the <prgn>postinst</prgn> script should
3522 install a <prgn>config</prgn> script in the control area,
3523 see <ref id="maintscriptprompt"> for details.
3527 When a package is upgraded a combination of the scripts from
3528 the old and new packages is called during the upgrade
3529 procedure. If your scripts are going to be at all
3530 complicated you need to be aware of this, and may need to
3531 check the arguments to your scripts.
3535 Broadly speaking the <prgn>preinst</prgn> is called before
3536 (a particular version of) a package is installed, and the
3537 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3538 before (a version of) a package is removed and the
3539 <prgn>postrm</prgn> afterwards.
3543 Programs called from maintainer scripts should not normally
3544 have a path prepended to them. Before installation is
3545 started, the package management system checks to see if the
3546 programs <prgn>ldconfig</prgn>,
3547 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3548 and <prgn>update-rc.d</prgn> can be found via the
3549 <tt>PATH</tt> environment variable. Those programs, and any
3550 other program that one would expect to be in the
3551 <tt>PATH</tt>, should thus be invoked without an absolute
3552 pathname. Maintainer scripts should also not reset the
3553 <tt>PATH</tt>, though they might choose to modify it by
3554 prepending or appending package-specific directories. These
3555 considerations really apply to all shell scripts.</p>
3558 <sect id="idempotency">
3559 <heading>Maintainer scripts idempotency</heading>
3562 It is necessary for the error recovery procedures that the
3563 scripts be idempotent. This means that if it is run
3564 successfully, and then it is called again, it doesn't bomb
3565 out or cause any harm, but just ensures that everything is
3566 the way it ought to be. If the first call failed, or
3567 aborted half way through for some reason, the second call
3568 should merely do the things that were left undone the first
3569 time, if any, and exit with a success status if everything
3571 This is so that if an error occurs, the user interrupts
3572 <prgn>dpkg</prgn> or some other unforeseen circumstance
3573 happens you don't leave the user with a badly-broken
3574 package when <prgn>dpkg</prgn> attempts to repeat the
3580 <sect id="controllingterminal">
3581 <heading>Controlling terminal for maintainer scripts</heading>
3584 Maintainer scripts are not guaranteed to run with a controlling
3585 terminal and may not be able to interact with the user. They
3586 must be able to fall back to noninteractive behavior if no
3587 controlling terminal is available. Maintainer scripts that
3588 prompt via a program conforming to the Debian Configuration
3589 Management Specification (see <ref id="maintscriptprompt">) may
3590 assume that program will handle falling back to noninteractive
3595 For high-priority prompts without a reasonable default answer,
3596 maintainer scripts may abort if there is no controlling
3597 terminal. However, this situation should be avoided if at all
3598 possible, since it prevents automated or unattended installs.
3599 In most cases, users will consider this to be a bug in the
3604 <sect id="exitstatus">
3605 <heading>Exit status</heading>
3608 Each script must return a zero exit status for
3609 success, or a nonzero one for failure, since the package
3610 management system looks for the exit status of these scripts
3611 and determines what action to take next based on that datum.
3615 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3620 <list compact="compact">
3622 <var>new-preinst</var> <tt>install</tt>
3625 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3628 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3631 <var>old-preinst</var> <tt>abort-upgrade</tt>
3632 <var>new-version</var>
3637 <list compact="compact">
3639 <var>postinst</var> <tt>configure</tt>
3640 <var>most-recently-configured-version</var>
3643 <var>old-postinst</var> <tt>abort-upgrade</tt>
3644 <var>new-version</var>
3647 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3648 <tt>in-favour</tt> <var>package</var>
3649 <var>new-version</var>
3652 <var>postinst</var> <tt>abort-remove</tt>
3655 <var>deconfigured's-postinst</var>
3656 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3657 <var>failed-install-package</var> <var>version</var>
3658 [<tt>removing</tt> <var>conflicting-package</var>
3664 <list compact="compact">
3666 <var>prerm</var> <tt>remove</tt>
3669 <var>old-prerm</var> <tt>upgrade</tt>
3670 <var>new-version</var>
3673 <var>new-prerm</var> <tt>failed-upgrade</tt>
3674 <var>old-version</var>
3677 <var>conflictor's-prerm</var> <tt>remove</tt>
3678 <tt>in-favour</tt> <var>package</var>
3679 <var>new-version</var>
3682 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3683 <tt>in-favour</tt> <var>package-being-installed</var>
3684 <var>version</var> [<tt>removing</tt>
3685 <var>conflicting-package</var>
3691 <list compact="compact">
3693 <var>postrm</var> <tt>remove</tt>
3696 <var>postrm</var> <tt>purge</tt>
3699 <var>old-postrm</var> <tt>upgrade</tt>
3700 <var>new-version</var>
3703 <var>new-postrm</var> <tt>failed-upgrade</tt>
3704 <var>old-version</var>
3707 <var>new-postrm</var> <tt>abort-install</tt>
3710 <var>new-postrm</var> <tt>abort-install</tt>
3711 <var>old-version</var>
3714 <var>new-postrm</var> <tt>abort-upgrade</tt>
3715 <var>old-version</var>
3718 <var>disappearer's-postrm</var> <tt>disappear</tt>
3719 <var>overwriter</var>
3720 <var>overwriter-version</var>
3726 <sect id="unpackphase">
3727 <heading>Details of unpack phase of installation or upgrade</heading>
3730 The procedure on installation/upgrade/overwrite/disappear
3731 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3732 stage of <tt>dpkg --install</tt>) is as follows. In each
3733 case, if a major error occurs (unless listed below) the
3734 actions are, in general, run backwards - this means that the
3735 maintainer scripts are run with different arguments in
3736 reverse order. These are the "error unwind" calls listed
3743 If a version of the package is already installed, call
3744 <example compact="compact">
3745 <var>old-prerm</var> upgrade <var>new-version</var>
3749 If the script runs but exits with a non-zero
3750 exit status, <prgn>dpkg</prgn> will attempt:
3751 <example compact="compact">
3752 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3754 If this works, the upgrade continues. If this
3755 does not work, the error unwind:
3756 <example compact="compact">
3757 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3759 If this works, then the old-version is
3760 "Installed", if not, the old version is in a
3761 "Half-Configured" state.
3767 If a "conflicting" package is being removed at the same time,
3768 or if any package will be broken (due to <tt>Breaks</tt>):
3771 If <tt>--auto-deconfigure</tt> is
3772 specified, call, for each package to be deconfigured
3773 due to <tt>Breaks</tt>:
3774 <example compact="compact">
3775 <var>deconfigured's-prerm</var> deconfigure \
3776 in-favour <var>package-being-installed</var> <var>version</var>
3779 <example compact="compact">
3780 <var>deconfigured's-postinst</var> abort-deconfigure \
3781 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3783 The deconfigured packages are marked as
3784 requiring configuration, so that if
3785 <tt>--install</tt> is used they will be
3786 configured again if possible.
3789 If any packages depended on a conflicting
3790 package being removed and <tt>--auto-deconfigure</tt> is
3791 specified, call, for each such package:
3792 <example compact="compact">
3793 <var>deconfigured's-prerm</var> deconfigure \
3794 in-favour <var>package-being-installed</var> <var>version</var> \
3795 removing <var>conflicting-package</var> <var>version</var>
3798 <example compact="compact">
3799 <var>deconfigured's-postinst</var> abort-deconfigure \
3800 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3801 removing <var>conflicting-package</var> <var>version</var>
3803 The deconfigured packages are marked as
3804 requiring configuration, so that if
3805 <tt>--install</tt> is used they will be
3806 configured again if possible.
3809 To prepare for removal of each conflicting package, call:
3810 <example compact="compact">
3811 <var>conflictor's-prerm</var> remove \
3812 in-favour <var>package</var> <var>new-version</var>
3815 <example compact="compact">
3816 <var>conflictor's-postinst</var> abort-remove \
3817 in-favour <var>package</var> <var>new-version</var>
3826 If the package is being upgraded, call:
3827 <example compact="compact">
3828 <var>new-preinst</var> upgrade <var>old-version</var>
3830 If this fails, we call:
3832 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3839 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3841 is called. If this works, then the old version
3842 is in an "Installed" state, or else it is left
3843 in an "Unpacked" state.
3848 If it fails, then the old version is left
3849 in an "Half-Installed" state.
3856 Otherwise, if the package had some configuration
3857 files from a previous version installed (i.e., it
3858 is in the "configuration files only" state):
3859 <example compact="compact">
3860 <var>new-preinst</var> install <var>old-version</var>
3864 <var>new-postrm</var> abort-install <var>old-version</var>
3866 If this fails, the package is left in a
3867 "Half-Installed" state, which requires a
3868 reinstall. If it works, the packages is left in
3869 a "Config-Files" state.
3872 Otherwise (i.e., the package was completely purged):
3873 <example compact="compact">
3874 <var>new-preinst</var> install
3877 <example compact="compact">
3878 <var>new-postrm</var> abort-install
3880 If the error-unwind fails, the package is in a
3881 "Half-Installed" phase, and requires a
3882 reinstall. If the error unwind works, the
3883 package is in a not installed state.
3890 The new package's files are unpacked, overwriting any
3891 that may be on the system already, for example any
3892 from the old version of the same package or from
3893 another package. Backups of the old files are kept
3894 temporarily, and if anything goes wrong the package
3895 management system will attempt to put them back as
3896 part of the error unwind.
3900 It is an error for a package to contain files which
3901 are on the system in another package, unless
3902 <tt>Replaces</tt> is used (see <ref id="replaces">).
3904 The following paragraph is not currently the case:
3905 Currently the <tt>- - force-overwrite</tt> flag is
3906 enabled, downgrading it to a warning, but this may not
3912 It is a more serious error for a package to contain a
3913 plain file or other kind of non-directory where another
3914 package has a directory (again, unless
3915 <tt>Replaces</tt> is used). This error can be
3916 overridden if desired using
3917 <tt>--force-overwrite-dir</tt>, but this is not
3922 Packages which overwrite each other's files produce
3923 behavior which, though deterministic, is hard for the
3924 system administrator to understand. It can easily
3925 lead to "missing" programs if, for example, a package
3926 is installed which overwrites a file from another
3927 package, and is then removed again.<footnote>
3928 Part of the problem is due to what is arguably a
3929 bug in <prgn>dpkg</prgn>.
3934 A directory will never be replaced by a symbolic link
3935 to a directory or vice versa; instead, the existing
3936 state (symlink or not) will be left alone and
3937 <prgn>dpkg</prgn> will follow the symlink if there is
3946 If the package is being upgraded, call
3947 <example compact="compact">
3948 <var>old-postrm</var> upgrade <var>new-version</var>
3952 If this fails, <prgn>dpkg</prgn> will attempt:
3953 <example compact="compact">
3954 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3956 If this works, installation continues. If not,
3958 <example compact="compact">
3959 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3961 If this fails, the old version is left in a
3962 "Half-Installed" state. If it works, dpkg now
3964 <example compact="compact">
3965 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3967 If this fails, the old version is left in a
3968 "Half-Installed" state. If it works, dpkg now
3970 <example compact="compact">
3971 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3973 If this fails, the old version is in an
3980 This is the point of no return - if
3981 <prgn>dpkg</prgn> gets this far, it won't back off
3982 past this point if an error occurs. This will
3983 leave the package in a fairly bad state, which
3984 will require a successful re-installation to clear
3985 up, but it's when <prgn>dpkg</prgn> starts doing
3986 things that are irreversible.
3991 Any files which were in the old version of the package
3992 but not in the new are removed.
3996 The new file list replaces the old.
4000 The new maintainer scripts replace the old.
4004 Any packages all of whose files have been overwritten
4005 during the installation, and which aren't required for
4006 dependencies, are considered to have been removed.
4007 For each such package
4010 <prgn>dpkg</prgn> calls:
4011 <example compact="compact">
4012 <var>disappearer's-postrm</var> disappear \
4013 <var>overwriter</var> <var>overwriter-version</var>
4017 The package's maintainer scripts are removed.
4020 It is noted in the status database as being in a
4021 sane state, namely not installed (any conffiles
4022 it may have are ignored, rather than being
4023 removed by <prgn>dpkg</prgn>). Note that
4024 disappearing packages do not have their prerm
4025 called, because <prgn>dpkg</prgn> doesn't know
4026 in advance that the package is going to
4033 Any files in the package we're unpacking that are also
4034 listed in the file lists of other packages are removed
4035 from those lists. (This will lobotomize the file list
4036 of the "conflicting" package if there is one.)
4040 The backup files made during installation, above, are
4046 The new package's status is now sane, and recorded as
4051 Here is another point of no return - if the
4052 conflicting package's removal fails we do not unwind
4053 the rest of the installation; the conflicting package
4054 is left in a half-removed limbo.
4059 If there was a conflicting package we go and do the
4060 removal actions (described below), starting with the
4061 removal of the conflicting package's files (any that
4062 are also in the package being installed have already
4063 been removed from the conflicting package's file list,
4064 and so do not get removed now).
4070 <sect id="configdetails"><heading>Details of configuration</heading>
4073 When we configure a package (this happens with <tt>dpkg
4074 --install</tt> and <tt>dpkg --configure</tt>), we first
4075 update any <tt>conffile</tt>s and then call:
4076 <example compact="compact">
4077 <var>postinst</var> configure <var>most-recently-configured-version</var>
4082 No attempt is made to unwind after errors during
4083 configuration. If the configuration fails, the package is in
4084 a "Failed Config" state, and an error message is generated.
4088 If there is no most recently configured version
4089 <prgn>dpkg</prgn> will pass a null argument.
4092 Historical note: Truly ancient (pre-1997) versions of
4093 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4094 (including the angle brackets) in this case. Even older
4095 ones did not pass a second argument at all, under any
4096 circumstance. Note that upgrades using such an old dpkg
4097 version are unlikely to work for other reasons, even if
4098 this old argument behavior is handled by your postinst script.
4104 <sect id="removedetails"><heading>Details of removal and/or
4105 configuration purging</heading>
4111 <example compact="compact">
4112 <var>prerm</var> remove
4116 If prerm fails during replacement due to conflict
4118 <var>conflictor's-postinst</var> abort-remove \
4119 in-favour <var>package</var> <var>new-version</var>
4123 <var>postinst</var> abort-remove
4127 If this fails, the package is in a "Half-Configured"
4128 state, or else it remains "Installed".
4132 The package's files are removed (except <tt>conffile</tt>s).
4135 <example compact="compact">
4136 <var>postrm</var> remove
4140 If it fails, there's no error unwind, and the package is in
4141 an "Half-Installed" state.
4146 All the maintainer scripts except the <prgn>postrm</prgn>
4151 If we aren't purging the package we stop here. Note
4152 that packages which have no <prgn>postrm</prgn> and no
4153 <tt>conffile</tt>s are automatically purged when
4154 removed, as there is no difference except for the
4155 <prgn>dpkg</prgn> status.
4159 The <tt>conffile</tt>s and any backup files
4160 (<tt>~</tt>-files, <tt>#*#</tt> files,
4161 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4166 <example compact="compact">
4167 <var>postrm</var> purge
4171 If this fails, the package remains in a "Config-Files"
4176 The package's file list is removed.
4185 <chapt id="relationships">
4186 <heading>Declaring relationships between packages</heading>
4188 <sect id="depsyntax">
4189 <heading>Syntax of relationship fields</heading>
4192 These fields all have a uniform syntax. They are a list of
4193 package names separated by commas.
4197 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4198 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4199 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4200 control file fields of the package, which declare
4201 dependencies on other packages, the package names listed may
4202 also include lists of alternative package names, separated
4203 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4204 if any one of the alternative packages is installed, that
4205 part of the dependency is considered to be satisfied.
4209 All of the fields except for <tt>Provides</tt> may restrict
4210 their applicability to particular versions of each named
4211 package. This is done in parentheses after each individual
4212 package name; the parentheses should contain a relation from
4213 the list below followed by a version number, in the format
4214 described in <ref id="f-Version">.
4218 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4219 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4220 strictly earlier, earlier or equal, exactly equal, later or
4221 equal and strictly later, respectively. The deprecated
4222 forms <tt><</tt> and <tt>></tt> were used to mean
4223 earlier/later or equal, rather than strictly earlier/later,
4224 so they should not appear in new packages (though
4225 <prgn>dpkg</prgn> still supports them).
4229 Whitespace may appear at any point in the version
4230 specification subject to the rules in <ref
4231 id="controlsyntax">, and must appear where it's necessary to
4232 disambiguate; it is not otherwise significant. All of the
4233 relationship fields may span multiple lines. For
4234 consistency and in case of future changes to
4235 <prgn>dpkg</prgn> it is recommended that a single space be
4236 used after a version relationship and before a version
4237 number; it is also conventional to put a single space after
4238 each comma, on either side of each vertical bar, and before
4239 each open parenthesis. When wrapping a relationship field, it
4240 is conventional to do so after a comma and before the space
4241 following that comma.
4245 For example, a list of dependencies might appear as:
4246 <example compact="compact">
4249 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4254 All fields that specify build-time relationships
4255 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4256 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
4257 may be restricted to a certain set of architectures. This
4258 is indicated in brackets after each individual package name and
4259 the optional version specification. The brackets enclose a
4260 list of Debian architecture names separated by whitespace.
4261 Exclamation marks may be prepended to each of the names.
4262 (It is not permitted for some names to be prepended with
4263 exclamation marks while others aren't.) If the current Debian
4264 host architecture is not in this list and there are no
4265 exclamation marks in the list, or it is in the list with a
4266 prepended exclamation mark, the package name and the
4267 associated version specification are ignored completely for
4268 the purposes of defining the relationships.
4273 <example compact="compact">
4275 Build-Depends-Indep: texinfo
4276 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4277 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4279 requires <tt>kernel-headers-2.2.10</tt> on all architectures
4280 other than hurd-i386 and requires <tt>hurd-dev</tt> and
4281 <tt>gnumach-dev</tt> only on hurd-i386.
4285 If the architecture-restricted dependency is part of a set of
4286 alternatives using <tt>|</tt>, that alternative is ignored
4287 completely on architectures that do not match the restriction.
4289 <example compact="compact">
4290 Build-Depends: foo [!i386] | bar [!amd64]
4292 is equivalent to <tt>bar</tt> on the i386 architecture, to
4293 <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
4294 bar</tt> on all other architectures.
4298 All fields that specify build-time relationships may also be
4299 restricted to a certain set of architectures using architecture
4300 wildcards. The syntax for declaring such restrictions is the
4301 same as declaring restrictions using a certain set of
4302 architectures without architecture wildcards. For example:
4303 <example compact="compact">
4304 Build-Depends: foo [linux-any], bar [any-i386], baz [!linux-any]
4306 is equivalent to <tt>foo</tt> on architectures using the Linux
4307 kernel and any cpu, <tt>bar</tt> on architectures using any
4308 kernel and an i386 cpu, and <tt>baz</tt> on any architecture
4309 using a kernel other than Linux.
4313 Note that the binary package relationship fields such as
4314 <tt>Depends</tt> appear in one of the binary package
4315 sections of the control file, whereas the build-time
4316 relationships such as <tt>Build-Depends</tt> appear in the
4317 source package section of the control file (which is the
4322 <sect id="binarydeps">
4323 <heading>Binary Dependencies - <tt>Depends</tt>,
4324 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4325 <tt>Pre-Depends</tt>
4329 Packages can declare in their control file that they have
4330 certain relationships to other packages - for example, that
4331 they may not be installed at the same time as certain other
4332 packages, and/or that they depend on the presence of others.
4336 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4337 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4338 <tt>Breaks</tt> and <tt>Conflicts</tt> control file fields.
4339 <tt>Breaks</tt> is described in <ref id="breaks">, and
4340 <tt>Conflicts</tt> is described in <ref id="conflicts">. The
4341 rest are described below.
4345 These seven fields are used to declare a dependency
4346 relationship by one package on another. Except for
4347 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4348 depending (binary) package's control file.
4349 (<tt>Enhances</tt> appears in the recommending package's
4350 control file, and <tt>Breaks</tt> appears in the version of
4351 depended-on package which causes the named package to
4356 A <tt>Depends</tt> field takes effect <em>only</em> when a
4357 package is to be configured. It does not prevent a package
4358 being on the system in an unconfigured state while its
4359 dependencies are unsatisfied, and it is possible to replace
4360 a package whose dependencies are satisfied and which is
4361 properly installed with a different version whose
4362 dependencies are not and cannot be satisfied; when this is
4363 done the depending package will be left unconfigured (since
4364 attempts to configure it will give errors) and will not
4365 function properly. If it is necessary, a
4366 <tt>Pre-Depends</tt> field can be used, which has a partial
4367 effect even when a package is being unpacked, as explained
4368 in detail below. (The other three dependency fields,
4369 <tt>Recommends</tt>, <tt>Suggests</tt> and
4370 <tt>Enhances</tt>, are only used by the various front-ends
4371 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4372 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4376 For this reason packages in an installation run are usually
4377 all unpacked first and all configured later; this gives
4378 later versions of packages with dependencies on later
4379 versions of other packages the opportunity to have their
4380 dependencies satisfied.
4384 In case of circular dependencies, since installation or
4385 removal order honoring the dependency order can't be
4386 established, dependency loops are broken at some point
4387 (based on rules below), and some packages may not be able to
4388 rely on their dependencies being present when being
4389 installed or removed, depending on which side of the break
4390 of the circular dependency loop they happen to be on. If one
4391 of the packages in the loop has no postinst script, then the
4392 cycle will be broken at that package, so as to ensure that
4393 all postinst scripts run with the dependencies properly
4394 configured if this is possible. Otherwise the breaking point
4399 The <tt>Depends</tt> field thus allows package maintainers
4400 to impose an order in which packages should be configured.
4404 The meaning of the five dependency fields is as follows:
4406 <tag><tt>Depends</tt></tag>
4409 This declares an absolute dependency. A package will
4410 not be configured unless all of the packages listed in
4411 its <tt>Depends</tt> field have been correctly
4416 The <tt>Depends</tt> field should be used if the
4417 depended-on package is required for the depending
4418 package to provide a significant amount of
4423 The <tt>Depends</tt> field should also be used if the
4424 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4425 <prgn>postrm</prgn> scripts require the package to be
4426 present in order to run. Note, however, that the
4427 <prgn>postrm</prgn> cannot rely on any non-essential
4428 packages to be present during the <tt>purge</tt>
4432 <tag><tt>Recommends</tt></tag>
4435 This declares a strong, but not absolute, dependency.
4439 The <tt>Recommends</tt> field should list packages
4440 that would be found together with this one in all but
4441 unusual installations.
4445 <tag><tt>Suggests</tt></tag>
4447 This is used to declare that one package may be more
4448 useful with one or more others. Using this field
4449 tells the packaging system and the user that the
4450 listed packages are related to this one and can
4451 perhaps enhance its usefulness, but that installing
4452 this one without them is perfectly reasonable.
4455 <tag><tt>Enhances</tt></tag>
4457 This field is similar to Suggests but works in the
4458 opposite direction. It is used to declare that a
4459 package can enhance the functionality of another
4463 <tag><tt>Pre-Depends</tt></tag>
4466 This field is like <tt>Depends</tt>, except that it
4467 also forces <prgn>dpkg</prgn> to complete installation
4468 of the packages named before even starting the
4469 installation of the package which declares the
4470 pre-dependency, as follows:
4474 When a package declaring a pre-dependency is about to
4475 be <em>unpacked</em> the pre-dependency can be
4476 satisfied if the depended-on package is either fully
4477 configured, <em>or even if</em> the depended-on
4478 package(s) are only unpacked or in the "Half-Configured"
4479 state, provided that they have been configured
4480 correctly at some point in the past (and not removed
4481 or partially removed since). In this case, both the
4482 previously-configured and currently unpacked or
4483 "Half-Configured" versions must satisfy any version
4484 clause in the <tt>Pre-Depends</tt> field.
4488 When the package declaring a pre-dependency is about
4489 to be <em>configured</em>, the pre-dependency will be
4490 treated as a normal <tt>Depends</tt>, that is, it will
4491 be considered satisfied only if the depended-on
4492 package has been correctly configured.
4496 <tt>Pre-Depends</tt> should be used sparingly,
4497 preferably only by packages whose premature upgrade or
4498 installation would hamper the ability of the system to
4499 continue with any upgrade that might be in progress.
4503 <tt>Pre-Depends</tt> are also required if the
4504 <prgn>preinst</prgn> script depends on the named
4505 package. It is best to avoid this situation if
4513 When selecting which level of dependency to use you should
4514 consider how important the depended-on package is to the
4515 functionality of the one declaring the dependency. Some
4516 packages are composed of components of varying degrees of
4517 importance. Such a package should list using
4518 <tt>Depends</tt> the package(s) which are required by the
4519 more important components. The other components'
4520 requirements may be mentioned as Suggestions or
4521 Recommendations, as appropriate to the components' relative
4527 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4530 When one binary package declares that it breaks another,
4531 <prgn>dpkg</prgn> will refuse to allow the package which
4532 declares <tt>Breaks</tt> be installed unless the broken
4533 package is deconfigured first, and it will refuse to
4534 allow the broken package to be reconfigured.
4538 A package will not be regarded as causing breakage merely
4539 because its configuration files are still installed; it must
4540 be at least "Half-Installed".
4544 A special exception is made for packages which declare that
4545 they break their own package name or a virtual package which
4546 they provide (see below): this does not count as a real
4551 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4552 version clause; such a <tt>Breaks</tt> is introduced in the
4553 version of an (implicit or explicit) dependency which
4554 violates an assumption or reveals a bug in earlier versions
4555 of the broken package. This use of <tt>Breaks</tt> will
4556 inform higher-level package management tools that broken
4557 package must be upgraded before the new one.
4561 If the breaking package also overwrites some files from the
4562 older package, it should use <tt>Replaces</tt> (not
4563 <tt>Conflicts</tt>) to ensure this goes smoothly.
4567 <sect id="conflicts">
4568 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4571 When one binary package declares a conflict with another
4572 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4573 refuse to allow them to be installed on the system at the
4578 If one package is to be installed, the other must be removed
4579 first - if the package being installed is marked as
4580 replacing (see <ref id="replaces">) the one on the system,
4581 or the one on the system is marked as deselected, or both
4582 packages are marked <tt>Essential</tt>, then
4583 <prgn>dpkg</prgn> will automatically remove the package
4584 which is causing the conflict, otherwise it will halt the
4585 installation of the new package with an error. This
4586 mechanism is specifically designed to produce an error when
4587 the installed package is <tt>Essential</tt>, but the new
4592 A package will not cause a conflict merely because its
4593 configuration files are still installed; it must be at least
4598 A special exception is made for packages which declare a
4599 conflict with their own package name, or with a virtual
4600 package which they provide (see below): this does not
4601 prevent their installation, and allows a package to conflict
4602 with others providing a replacement for it. You use this
4603 feature when you want the package in question to be the only
4604 package providing some feature.
4608 A <tt>Conflicts</tt> entry should almost never have an
4609 "earlier than" version clause. This would prevent
4610 <prgn>dpkg</prgn> from upgrading or installing the package
4611 which declared such a conflict until the upgrade or removal
4612 of the conflicted-with package had been completed. Instead,
4613 <tt>Breaks</tt> may be used.
4617 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4621 As well as the names of actual ("concrete") packages, the
4622 package relationship fields <tt>Depends</tt>,
4623 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4624 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4625 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4626 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4627 may mention "virtual packages".
4631 A <em>virtual package</em> is one which appears in the
4632 <tt>Provides</tt> control file field of another package.
4633 The effect is as if the package(s) which provide a
4634 particular virtual package name had been listed by name
4635 everywhere the virtual package name appears. (See also <ref
4640 If there are both concrete and virtual packages of the same
4641 name, then the dependency may be satisfied (or the conflict
4642 caused) by either the concrete package with the name in
4643 question or any other concrete package which provides the
4644 virtual package with the name in question. This is so that,
4645 for example, supposing we have
4646 <example compact="compact">
4649 </example> and someone else releases an enhanced version of
4650 the <tt>bar</tt> package they can say:
4651 <example compact="compact">
4655 and the <tt>bar-plus</tt> package will now also satisfy the
4656 dependency for the <tt>foo</tt> package.
4660 If a relationship field has a version number attached
4661 then only real packages will be considered to see whether
4662 the relationship is satisfied (or the prohibition violated,
4663 for a conflict or breakage) - it is assumed that a real
4664 package which provides the virtual package is not of the
4665 "right" version. So, a <tt>Provides</tt> field may not
4666 contain version numbers, and the version number of the
4667 concrete package which provides a particular virtual package
4668 will not be looked at when considering a dependency on or
4669 conflict with the virtual package name.
4673 It is likely that the ability will be added in a future
4674 release of <prgn>dpkg</prgn> to specify a version number for
4675 each virtual package it provides. This feature is not yet
4676 present, however, and is expected to be used only
4681 If you want to specify which of a set of real packages
4682 should be the default to satisfy a particular dependency on
4683 a virtual package, you should list the real package as an
4684 alternative before the virtual one.
4689 <sect id="replaces"><heading>Overwriting files and replacing
4690 packages - <tt>Replaces</tt></heading>
4693 Packages can declare in their control file that they should
4694 overwrite files in certain other packages, or completely
4695 replace other packages. The <tt>Replaces</tt> control file
4696 field has these two distinct purposes.
4699 <sect1><heading>Overwriting files in other packages</heading>
4702 Firstly, as mentioned before, it is usually an error for a
4703 package to contain files which are on the system in
4708 However, if the overwriting package declares that it
4709 <tt>Replaces</tt> the one containing the file being
4710 overwritten, then <prgn>dpkg</prgn> will replace the file
4711 from the old package with that from the new. The file
4712 will no longer be listed as "owned" by the old package.
4716 If a package is completely replaced in this way, so that
4717 <prgn>dpkg</prgn> does not know of any files it still
4718 contains, it is considered to have "disappeared". It will
4719 be marked as not wanted on the system (selected for
4720 removal) and not installed. Any <tt>conffile</tt>s
4721 details noted for the package will be ignored, as they
4722 will have been taken over by the overwriting package. The
4723 package's <prgn>postrm</prgn> script will be run with a
4724 special argument to allow the package to do any final
4725 cleanup required. See <ref id="mscriptsinstact">.
4728 Replaces is a one way relationship -- you have to
4729 install the replacing package after the replaced
4736 For this usage of <tt>Replaces</tt>, virtual packages (see
4737 <ref id="virtual">) are not considered when looking at a
4738 <tt>Replaces</tt> field - the packages declared as being
4739 replaced must be mentioned by their real names.
4743 Furthermore, this usage of <tt>Replaces</tt> only takes
4744 effect when both packages are at least partially on the
4745 system at once, so that it can only happen if they do not
4746 conflict or if the conflict has been overridden.
4751 <sect1><heading>Replacing whole packages, forcing their
4755 Secondly, <tt>Replaces</tt> allows the packaging system to
4756 resolve which package should be removed when there is a
4757 conflict - see <ref id="conflicts">. This usage only
4758 takes effect when the two packages <em>do</em> conflict,
4759 so that the two usages of this field do not interfere with
4764 In this situation, the package declared as being replaced
4765 can be a virtual package, so for example, all mail
4766 transport agents (MTAs) would have the following fields in
4767 their control files:
4768 <example compact="compact">
4769 Provides: mail-transport-agent
4770 Conflicts: mail-transport-agent
4771 Replaces: mail-transport-agent
4773 ensuring that only one MTA can be installed at any one
4778 <sect id="sourcebinarydeps">
4779 <heading>Relationships between source and binary packages -
4780 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4781 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4785 Source packages that require certain binary packages to be
4786 installed or absent at the time of building the package
4787 can declare relationships to those binary packages.
4791 This is done using the <tt>Build-Depends</tt>,
4792 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4793 <tt>Build-Conflicts-Indep</tt> control file fields.
4797 Build-dependencies on "build-essential" binary packages can be
4798 omitted. Please see <ref id="pkg-relations"> for more information.
4802 The dependencies and conflicts they define must be satisfied
4803 (as defined earlier for binary packages) in order to invoke
4804 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4806 If you make "build-arch" or "binary-arch", you need
4807 Build-Depends. If you make "build-indep" or
4808 "binary-indep", you need Build-Depends and
4809 Build-Depends-Indep. If you make "build" or "binary",
4813 There is no Build-Depends-Arch; this role is essentially
4814 met with Build-Depends. Anyone building the
4815 <tt>build-indep</tt> and binary-indep<tt></tt> targets
4816 is basically assumed to be building the whole package
4817 anyway and so installs all build dependencies. The
4818 autobuilders use <tt>dpkg-buildpackage -B</tt>, which
4819 calls <tt>build</tt> (not <tt>build-arch</tt>, since it
4820 does not yet know how to check for its existence) and
4821 <tt>binary-arch</tt>.
4824 The purpose of the original split, I recall, was so that
4825 the autobuilders wouldn't need to install extra packages
4826 needed only for the binary-indep targets. But without a
4827 build-arch/build-indep split, this didn't work, since
4828 most of the work is done in the build target, not in the
4834 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4836 The <tt>Build-Depends</tt> and
4837 <tt>Build-Conflicts</tt> fields must be satisfied when
4838 any of the following targets is invoked:
4839 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4840 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4841 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4843 <tag><tt>Build-Depends-Indep</tt>,
4844 <tt>Build-Conflicts-Indep</tt></tag>
4846 The <tt>Build-Depends-Indep</tt> and
4847 <tt>Build-Conflicts-Indep</tt> fields must be
4848 satisfied when any of the following targets is
4849 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4850 <tt>binary</tt> and <tt>binary-indep</tt>.
4860 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4863 Packages containing shared libraries must be constructed with
4864 a little care to make sure that the shared library is always
4865 available. This is especially important for packages whose
4866 shared libraries are vitally important, such as the C library
4867 (currently <tt>libc6</tt>).
4871 Packages involving shared libraries should be split up into
4872 several binary packages. This section mostly deals with how
4873 this separation is to be accomplished; rules for files within
4874 the shared library packages are in <ref id="libraries"> instead.
4877 <sect id="sharedlibs-runtime">
4878 <heading>Run-time shared libraries</heading>
4881 The run-time shared library needs to be placed in a package
4882 whose name changes whenever the shared object version
4885 Since it is common place to install several versions of a
4886 package that just provides shared libraries, it is a
4887 good idea that the library package should not
4888 contain any extraneous non-versioned files, unless they
4889 happen to be in versioned directories.</p>
4891 The most common mechanism is to place it in a package
4893 <package><var>libraryname</var><var>soversion</var></package>,
4894 where <file><var>soversion</var></file> is the version number
4895 in the soname of the shared library<footnote>
4896 The soname is the shared object name: it's the thing
4897 that has to match exactly between building an executable
4898 and running it for the dynamic linker to be able run the
4899 program. For example, if the soname of the library is
4900 <file>libfoo.so.6</file>, the library package would be
4901 called <file>libfoo6</file>.
4903 Alternatively, if it would be confusing to directly append
4904 <var>soversion</var> to <var>libraryname</var> (e.g. because
4905 <var>libraryname</var> itself ends in a number), you may use
4906 <package><var>libraryname</var>-<var>soversion</var></package> and
4907 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4912 If you have several shared libraries built from the same
4913 source tree you may lump them all together into a single
4914 shared library package, provided that you change all of
4915 their sonames at once (so that you don't get filename
4916 clashes if you try to install different versions of the
4917 combined shared libraries package).
4921 The package should install the shared libraries under
4922 their normal names. For example, the <package>libgdbm3</package>
4923 package should install <file>libgdbm.so.3.0.0</file> as
4924 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4925 renamed or re-linked by any <prgn>prerm</prgn> or
4926 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4927 of renaming things safely without affecting running programs,
4928 and attempts to interfere with this are likely to lead to
4933 Shared libraries should not be installed executable, since
4934 the dynamic linker does not require this and trying to
4935 execute a shared library usually results in a core dump.
4939 The run-time library package should include the symbolic link that
4940 <prgn>ldconfig</prgn> would create for the shared libraries.
4941 For example, the <package>libgdbm3</package> package should include
4942 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4943 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4944 linker (for example <prgn>ld.so</prgn> or
4945 <prgn>ld-linux.so.*</prgn>) can find the library between the
4946 time that <prgn>dpkg</prgn> installs it and the time that
4947 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4949 The package management system requires the library to be
4950 placed before the symbolic link pointing to it in the
4951 <file>.deb</file> file. This is so that when
4952 <prgn>dpkg</prgn> comes to install the symlink
4953 (overwriting the previous symlink pointing at an older
4954 version of the library), the new shared library is already
4955 in place. In the past, this was achieved by creating the
4956 library in the temporary packaging directory before
4957 creating the symlink. Unfortunately, this was not always
4958 effective, since the building of the tar file in the
4959 <file>.deb</file> depended on the behavior of the underlying
4960 file system. Some file systems (such as reiserfs) reorder
4961 the files so that the order of creation is forgotten.
4962 Since version 1.7.0, <prgn>dpkg</prgn>
4963 reorders the files itself as necessary when building a
4964 package. Thus it is no longer important to concern
4965 oneself with the order of file creation.
4969 <sect1 id="ldconfig">
4970 <heading><tt>ldconfig</tt></heading>
4973 Any package installing shared libraries in one of the default
4974 library directories of the dynamic linker (which are currently
4975 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4976 listed in <file>/etc/ld.so.conf</file><footnote>
4978 <list compact="compact">
4979 <item>/usr/local/lib</item>
4980 <item>/usr/lib/libc5-compat</item>
4981 <item>/lib/libc5-compat</item>
4984 must use <prgn>ldconfig</prgn> to update the shared library
4989 The package maintainer scripts must only call
4990 <prgn>ldconfig</prgn> under these circumstances:
4991 <list compact="compact">
4992 <item>When the <prgn>postinst</prgn> script is run with a
4993 first argument of <tt>configure</tt>, the script must call
4994 <prgn>ldconfig</prgn>, and may optionally invoke
4995 <prgn>ldconfig</prgn> at other times.
4997 <item>When the <prgn>postrm</prgn> script is run with a
4998 first argument of <tt>remove</tt>, the script should call
4999 <prgn>ldconfig</prgn>.
5004 During install or upgrade, the preinst is called before
5005 the new files are installed, so calling "ldconfig" is
5006 pointless. The preinst of an existing package can also be
5007 called if an upgrade fails. However, this happens during
5008 the critical time when a shared libs may exist on-disk
5009 under a temporary name. Thus, it is dangerous and
5010 forbidden by current policy to call "ldconfig" at this
5015 When a package is installed or upgraded, "postinst
5016 configure" runs after the new files are safely on-disk.
5017 Since it is perfectly safe to invoke ldconfig
5018 unconditionally in a postinst, it is OK for a package to
5019 simply put ldconfig in its postinst without checking the
5020 argument. The postinst can also be called to recover from
5021 a failed upgrade. This happens before any new files are
5022 unpacked, so there is no reason to call "ldconfig" at this
5027 For a package that is being removed, prerm is
5028 called with all the files intact, so calling ldconfig is
5029 useless. The other calls to "prerm" happen in the case of
5030 upgrade at a time when all the files of the old package
5031 are on-disk, so again calling "ldconfig" is pointless.
5035 postrm, on the other hand, is called with the "remove"
5036 argument just after the files are removed, so this is
5037 the proper time to call "ldconfig" to notify the system
5038 of the fact that the shared libraries from the package
5039 are removed. The postrm can be called at several other
5040 times. At the time of "postrm purge", "postrm
5041 abort-install", or "postrm abort-upgrade", calling
5042 "ldconfig" is useless because the shared lib files are
5043 not on-disk. However, when "postrm" is invoked with
5044 arguments "upgrade", "failed-upgrade", or "disappear", a
5045 shared lib may exist on-disk under a temporary filename.
5053 <sect id="sharedlibs-support-files">
5054 <heading>Shared library support files</heading>
5057 If your package contains files whose names do not change with
5058 each change in the library shared object version, you must not
5059 put them in the shared library package. Otherwise, several
5060 versions of the shared library cannot be installed at the same
5061 time without filename clashes, making upgrades and transitions
5062 unnecessarily difficult.
5066 It is recommended that supporting files and run-time support
5067 programs that do not need to be invoked manually by users, but
5068 are nevertheless required for the package to function, be placed
5069 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
5070 preferably under <file>/usr/lib/</file><var>package-name</var>.
5071 If the program or file is architecture independent, the
5072 recommendation is for it to be placed in a subdirectory of
5073 <file>/usr/share</file> instead, preferably under
5074 <file>/usr/share/</file><var>package-name</var>. Following the
5075 <var>package-name</var> naming convention ensures that the file
5076 names change when the shared object version changes.
5080 Run-time support programs that use the shared library but are
5081 not required for the library to function or files used by the
5082 shared library that can be used by any version of the shared
5083 library package should instead be put in a separate package.
5084 This package might typically be named
5085 <package><var>libraryname</var>-tools</package>; note the
5086 absence of the <var>soversion</var> in the package name.
5090 Files and support programs only useful when compiling software
5091 against the library should be included in the development
5092 package for the library.<footnote>
5093 For example, a <file><var>package-name</var>-config</file>
5094 script or <package>pkg-config</package> configuration files.
5099 <sect id="sharedlibs-static">
5100 <heading>Static libraries</heading>
5103 The static library (<file><var>libraryname.a</var></file>)
5104 is usually provided in addition to the shared version.
5105 It is placed into the development package (see below).
5109 In some cases, it is acceptable for a library to be
5110 available in static form only; these cases include:
5112 <item>libraries for languages whose shared library support
5113 is immature or unstable</item>
5114 <item>libraries whose interfaces are in flux or under
5115 development (commonly the case when the library's
5116 major version number is zero, or where the ABI breaks
5117 across patchlevels)</item>
5118 <item>libraries which are explicitly intended to be
5119 available only in static form by their upstream
5124 <sect id="sharedlibs-dev">
5125 <heading>Development files</heading>
5128 The development files associated to a shared library need to be
5129 placed in a package called
5130 <package><var>libraryname</var><var>soversion</var>-dev</package>,
5131 or if you prefer only to support one development version at a
5132 time, <package><var>libraryname</var>-dev</package>.
5136 In case several development versions of a library exist, you may
5137 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5138 <ref id="conflicts">) to ensure that the user only installs one
5139 development version at a time (as different development versions are
5140 likely to have the same header files in them, which would cause a
5141 filename clash if both were installed).
5145 The development package should contain a symlink for the associated
5146 shared library without a version number. For example, the
5147 <package>libgdbm-dev</package> package should include a symlink
5148 from <file>/usr/lib/libgdbm.so</file> to
5149 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5150 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5151 <file>libgdbm.so</file> when compiling dynamically.
5155 <sect id="sharedlibs-intradeps">
5156 <heading>Dependencies between the packages of the same library</heading>
5159 Typically the development version should have an exact
5160 version dependency on the runtime library, to make sure that
5161 compilation and linking happens correctly. The
5162 <tt>${binary:Version}</tt> substitution variable can be
5163 useful for this purpose.
5165 Previously, <tt>${Source-Version}</tt> was used, but its name
5166 was confusing and it has been deprecated since dpkg 1.13.19.
5171 <sect id="sharedlibs-shlibdeps">
5172 <heading>Dependencies between the library and other packages -
5173 the <tt>shlibs</tt> system</heading>
5176 If a package contains a binary or library which links to a
5177 shared library, we must ensure that when the package is
5178 installed on the system, all of the libraries needed are
5179 also installed. This requirement led to the creation of the
5180 <tt>shlibs</tt> system, which is very simple in its design:
5181 any package which <em>provides</em> a shared library also
5182 provides information on the package dependencies required to
5183 ensure the presence of this library, and any package which
5184 <em>uses</em> a shared library uses this information to
5185 determine the dependencies it requires. The files which
5186 contain the mapping from shared libraries to the necessary
5187 dependency information are called <file>shlibs</file> files.
5191 Thus, when a package is built which contains any shared
5192 libraries, it must provide a <file>shlibs</file> file for other
5193 packages to use, and when a package is built which contains
5194 any shared libraries or compiled binaries, it must run
5195 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5196 on these to determine the libraries used and hence the
5197 dependencies needed by this package.<footnote>
5199 In the past, the shared libraries linked to were
5200 determined by calling <prgn>ldd</prgn>, but now
5201 <prgn>objdump</prgn> is used to do this. The only
5202 change this makes to package building is that
5203 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
5204 libraries, whereas in the past this was unnecessary.
5205 The rest of this footnote explains the advantage that
5210 We say that a binary <tt>foo</tt> <em>directly</em> uses
5211 a library <tt>libbar</tt> if it is explicitly linked
5212 with that library (that is, it uses the flag
5213 <tt>-lbar</tt> during the linking stage). Other
5214 libraries that are needed by <tt>libbar</tt> are linked
5215 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5216 linker will load them automatically when it loads
5217 <tt>libbar</tt>. A package should depend on
5218 the libraries it directly uses, and the dependencies for
5219 those libraries should automatically pull in the other
5224 Unfortunately, the <prgn>ldd</prgn> program shows both
5225 the directly and indirectly used libraries, meaning that
5226 the dependencies determined included both direct and
5227 indirect dependencies. The use of <prgn>objdump</prgn>
5228 avoids this problem by determining only the directly
5233 A good example of where this helps is the following. We
5234 could update <tt>libimlib</tt> with a new version that
5235 supports a new graphics format called dgf (but retaining
5236 the same major version number). If we used the old
5237 <prgn>ldd</prgn> method, every package that uses
5238 <tt>libimlib</tt> would need to be recompiled so it
5239 would also depend on <tt>libdgf</tt> or it wouldn't run
5240 due to missing symbols. However with the new system,
5241 packages using <tt>libimlib</tt> can rely on
5242 <tt>libimlib</tt> itself having the dependency on
5243 <tt>libdgf</tt> and so they would not need rebuilding.
5249 In the following sections, we will first describe where the
5250 various <tt>shlibs</tt> files are to be found, then how to
5251 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5252 file format and how to create them if your package contains a
5257 <heading>The <tt>shlibs</tt> files present on the system</heading>
5260 There are several places where <tt>shlibs</tt> files are
5261 found. The following list gives them in the order in which
5263 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5264 (The first one which gives the required information is used.)
5270 <p><file>debian/shlibs.local</file></p>
5273 This lists overrides for this package. Its use is
5274 described below (see <ref id="shlibslocal">).
5279 <p><file>/etc/dpkg/shlibs.override</file></p>
5282 This lists global overrides. This list is normally
5283 empty. It is maintained by the local system
5289 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5292 When packages are being built, any
5293 <file>debian/shlibs</file> files are copied into the
5294 control file area of the temporary build directory and
5295 given the name <file>shlibs</file>. These files give
5296 details of any shared libraries included in the
5298 An example may help here. Let us say that the
5299 source package <tt>foo</tt> generates two binary
5300 packages, <tt>libfoo2</tt> and
5301 <tt>foo-runtime</tt>. When building the binary
5302 packages, the two packages are created in the
5303 directories <file>debian/libfoo2</file> and
5304 <file>debian/foo-runtime</file> respectively.
5305 (<file>debian/tmp</file> could be used instead of one
5306 of these.) Since <tt>libfoo2</tt> provides the
5307 <tt>libfoo</tt> shared library, it will require a
5308 <tt>shlibs</tt> file, which will be installed in
5309 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
5311 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
5312 when <prgn>dpkg-shlibdeps</prgn> is run on the
5314 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
5316 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5317 determine whether <tt>foo-prog</tt>'s library
5318 dependencies are satisfied by any of the libraries
5319 provided by <tt>libfoo2</tt>. For this reason,
5320 <prgn>dpkg-shlibdeps</prgn> must only be run once
5321 all of the individual binary packages'
5322 <tt>shlibs</tt> files have been installed into the
5329 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5332 These are the <file>shlibs</file> files corresponding to
5333 all of the packages installed on the system, and are
5334 maintained by the relevant package maintainers.
5339 <p><file>/etc/dpkg/shlibs.default</file></p>
5342 This file lists any shared libraries whose packages
5343 have failed to provide correct <file>shlibs</file> files.
5344 It was used when the <file>shlibs</file> setup was first
5345 introduced, but it is now normally empty. It is
5346 maintained by the <tt>dpkg</tt> maintainer.
5354 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5355 <file>shlibs</file> files</heading>
5359 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5360 into your <file>debian/rules</file> file. If your package
5361 contains only compiled binaries and libraries (but no scripts),
5362 you can use a command such as:
5363 <example compact="compact">
5364 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5365 debian/tmp/usr/lib/*
5367 Otherwise, you will need to explicitly list the compiled
5368 binaries and libraries.<footnote>
5369 If you are using <tt>debhelper</tt>, the
5370 <prgn>dh_shlibdeps</prgn> program will do this work for
5371 you. It will also correctly handle multi-binary
5377 This command puts the dependency information into the
5378 <file>debian/substvars</file> file, which is then used by
5379 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5380 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5381 field in the control file for this to work.
5385 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
5386 done. If it does complain you might need to create your own
5387 <file>debian/shlibs.local</file> file, as explained below (see
5388 <ref id="shlibslocal">).
5392 If you have multiple binary packages, you will need to call
5393 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5394 compiled libraries or binaries. In such a case, you will
5395 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5396 utilities to specify a different <file>substvars</file> file.
5400 If you are creating a udeb for use in the Debian Installer,
5401 you will need to specify that <prgn>dpkg-shlibdeps</prgn>
5402 should use the dependency line of type <tt>udeb</tt> by
5403 adding the <tt>-tudeb</tt> option<footnote>
5404 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5405 will automatically add this option if it knows it is
5407 </footnote>. If there is no dependency line of type <tt>udeb</tt>
5408 in the <file>shlibs</file> file, <prgn>dpkg-shlibdeps</prgn> will
5409 fall back to the regular dependency line.
5413 For more details on dpkg-shlibdeps, please see
5414 <ref id="pkg-dpkg-shlibdeps"> and
5415 <manref name="dpkg-shlibdeps" section="1">.
5420 <heading>The <file>shlibs</file> File Format</heading>
5423 Each <file>shlibs</file> file has the same format. Lines
5424 beginning with <tt>#</tt> are considered to be comments and
5425 are ignored. Each line is of the form:
5426 <example compact="compact">
5427 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5432 We will explain this by reference to the example of the
5433 <tt>zlib1g</tt> package, which (at the time of writing)
5434 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5438 <var>type</var> is an optional element that indicates the type
5439 of package for which the line is valid. The only type currently
5440 in use is <tt>udeb</tt>. The colon and space after the type are
5445 <var>library-name</var> is the name of the shared library,
5446 in this case <tt>libz</tt>. (This must match the name part
5447 of the soname, see below.)
5451 <var>soname-version</var> is the version part of the soname of
5452 the library. The soname is the thing that must exactly match
5453 for the library to be recognized by the dynamic linker, and is
5455 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5456 example, <tt>libz.so.1</tt>.<footnote>
5457 This can be determined using the command
5458 <example compact="compact">
5459 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5462 The version part is the part which comes after
5463 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
5467 <var>dependencies</var> has the same syntax as a dependency
5468 field in a binary package control file. It should give
5469 details of which packages are required to satisfy a binary
5470 built against the version of the library contained in the
5471 package. See <ref id="depsyntax"> for details.
5475 In our example, if the first version of the <tt>zlib1g</tt>
5476 package which contained a minor number of at least
5477 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5478 <tt>shlibs</tt> entry for this library could say:
5479 <example compact="compact">
5480 libz 1 zlib1g (>= 1:1.1.3)
5482 The version-specific dependency is to avoid warnings from
5483 the dynamic linker about using older shared libraries with
5488 As zlib1g also provides a udeb containing the shared library,
5489 there would also be a second line:
5490 <example compact="compact">
5491 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5497 <heading>Providing a <file>shlibs</file> file</heading>
5500 If your package provides a shared library, you need to create
5501 a <file>shlibs</file> file following the format described above.
5502 It is usual to call this file <file>debian/shlibs</file> (but if
5503 you have multiple binary packages, you might want to call it
5504 <file>debian/shlibs.<var>package</var></file> instead). Then
5505 let <file>debian/rules</file> install it in the control area:
5506 <example compact="compact">
5507 install -m644 debian/shlibs debian/tmp/DEBIAN
5509 or, in the case of a multi-binary package:
5510 <example compact="compact">
5511 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5513 An alternative way of doing this is to create the
5514 <file>shlibs</file> file in the control area directly from
5515 <file>debian/rules</file> without using a <file>debian/shlibs</file>
5516 file at all,<footnote>
5517 This is what <prgn>dh_makeshlibs</prgn> in the
5518 <tt>debhelper</tt> suite does. If your package also has a udeb
5519 that provides a shared library, <prgn>dh_makeshlibs</prgn> can
5520 automatically generate the <tt>udeb:</tt> lines if you specify
5521 the name of the udeb with the <tt>--add-udeb</tt> option.
5523 since the <file>debian/shlibs</file> file itself is ignored by
5524 <prgn>dpkg-shlibdeps</prgn>.
5528 As <prgn>dpkg-shlibdeps</prgn> reads the
5529 <file>DEBIAN/shlibs</file> files in all of the binary packages
5530 being built from this source package, all of the
5531 <file>DEBIAN/shlibs</file> files should be installed before
5532 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5537 <sect1 id="shlibslocal">
5538 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
5541 This file is intended only as a <em>temporary</em> fix if
5542 your binaries or libraries depend on a library whose package
5543 does not yet provide a correct <file>shlibs</file> file.
5547 We will assume that you are trying to package a binary
5548 <tt>foo</tt>. When you try running
5549 <prgn>dpkg-shlibdeps</prgn> you get the following error
5550 message (<tt>-O</tt> displays the dependency information on
5551 <tt>stdout</tt> instead of writing it to
5552 <tt>debian/substvars</tt>, and the lines have been wrapped
5553 for ease of reading):
5554 <example compact="compact">
5555 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
5556 dpkg-shlibdeps: warning: unable to find dependency
5557 information for shared library libbar (soname 1,
5558 path /usr/lib/libbar.so.1, dependency field Depends)
5559 shlibs:Depends=libc6 (>= 2.2.2-2)
5561 You can then run <prgn>ldd</prgn> on the binary to find the
5562 full location of the library concerned:
5563 <example compact="compact">
5565 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5566 libc.so.6 => /lib/libc.so.6 (0x40032000)
5567 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5569 So the <prgn>foo</prgn> binary depends on the
5570 <prgn>libbar</prgn> shared library, but no package seems to
5571 provide a <file>*.shlibs</file> file handling
5572 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5573 determine the package responsible:
5574 <example compact="compact">
5575 $ dpkg -S /usr/lib/libbar.so.1
5576 bar1: /usr/lib/libbar.so.1
5577 $ dpkg -s bar1 | grep Version
5580 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5581 is the one we are using. Now we can file a bug against the
5582 <tt>bar1</tt> package and create our own
5583 <file>debian/shlibs.local</file> to locally fix the problem.
5584 Including the following line into your
5585 <file>debian/shlibs.local</file> file:
5586 <example compact="compact">
5587 libbar 1 bar1 (>= 1.0-1)
5589 should allow the package build to work.
5593 As soon as the maintainer of <tt>bar1</tt> provides a
5594 correct <file>shlibs</file> file, you should remove this line
5595 from your <file>debian/shlibs.local</file> file. (You should
5596 probably also then have a versioned <tt>Build-Depends</tt>
5597 on <tt>bar1</tt> to help ensure that others do not have the
5598 same problem building your package.)
5607 <chapt id="opersys"><heading>The Operating System</heading>
5610 <heading>File system hierarchy</heading>
5614 <heading>File System Structure</heading>
5617 The location of all installed files and directories must
5618 comply with the Filesystem Hierarchy Standard (FHS),
5619 version 2.3, with the exceptions noted below, and except
5620 where doing so would violate other terms of Debian
5621 Policy. The following exceptions to the FHS apply:
5626 The optional rules related to user specific
5627 configuration files for applications are stored in
5628 the user's home directory are relaxed. It is
5629 recommended that such files start with the
5630 '<tt>.</tt>' character (a "dot file"), and if an
5631 application needs to create more than one dot file
5632 then the preferred placement is in a subdirectory
5633 with a name starting with a '.' character, (a "dot
5634 directory"). In this case it is recommended the
5635 configuration files not start with the '.'
5641 The requirement for amd64 to use <file>/lib64</file>
5642 for 64 bit binaries is removed.
5647 The requirement for object files, internal binaries, and
5648 libraries, including <file>libc.so.*</file>, to be located
5649 directly under <file>/lib{,32}</file> and
5650 <file>/usr/lib{,32}</file> is amended, permitting files
5651 to instead be installed to
5652 <file>/lib/<var>triplet</var></file> and
5653 <file>/usr/lib/<var>triplet</var></file>, where
5654 <tt><var>triplet</var></tt> is the value returned by
5655 <tt>dpkg-architecture -qDEB_HOST_GNU_TYPE</tt> for the
5656 architecture of the package. Packages may <em>not</em>
5657 install files to any <var>triplet</var> path other
5658 than the one matching the architecture of that package;
5659 for instance, an <tt>Architecture: amd64</tt> package
5660 containing 32-bit x86 libraries may not install these
5661 libraries to <file>/usr/lib/i486-linux-gnu</file>.
5663 This is necessary in order to reserve the directories for
5664 use in cross-installation of library packages from other
5665 architectures, as part of the planned deployment of
5670 Applications may also use a single subdirectory under
5671 <file>/usr/lib/<var>triplet</var></file>.
5674 The execution time linker/loader, ld*, must still be made
5675 available in the existing location under /lib or /lib64
5676 since this is part of the ELF ABI for the architecture.
5681 The requirement that
5682 <file>/usr/local/share/man</file> be "synonymous"
5683 with <file>/usr/local/man</file> is relaxed to a
5688 The requirement that windowmanagers with a single
5689 configuration file call it <file>system.*wmrc</file>
5690 is removed, as is the restriction that the window
5691 manager subdirectory be named identically to the
5692 window manager name itself.
5697 The requirement that boot manager configuration
5698 files live in <file>/etc</file>, or at least are
5699 symlinked there, is relaxed to a recommendation.
5704 The following directories in the root filesystem are
5705 additionally allowed: <file>/sys</file> and
5706 <file>/selinux</file>. <footnote>These directories
5707 are used as mount points to mount virtual filesystems
5708 to get access to kernel information.</footnote>
5715 The version of this document referred here can be
5716 found in the <tt>debian-policy</tt> package or on <url
5717 id="http://www.debian.org/doc/packaging-manuals/fhs/"
5718 name="FHS (Debian copy)"> alongside this manual (or, if
5719 you have the <package>debian-policy</package> installed,
5721 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5722 (local copy)">). The
5723 latest version, which may be a more recent version, may
5725 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5726 Specific questions about following the standard may be
5727 asked on the <tt>debian-devel</tt> mailing list, or
5728 referred to the FHS mailing list (see the
5729 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5735 <heading>Site-specific programs</heading>
5738 As mandated by the FHS, packages must not place any
5739 files in <file>/usr/local</file>, either by putting them in
5740 the file system archive to be unpacked by <prgn>dpkg</prgn>
5741 or by manipulating them in their maintainer scripts.
5745 However, the package may create empty directories below
5746 <file>/usr/local</file> so that the system administrator knows
5747 where to place site-specific files. These are not
5748 directories <em>in</em> <file>/usr/local</file>, but are
5749 children of directories in <file>/usr/local</file>. These
5750 directories (<file>/usr/local/*/dir/</file>)
5751 should be removed on package removal if they are
5756 Note that this applies only to
5757 directories <em>below</em> <file>/usr/local</file>,
5758 not <em>in</em> <file>/usr/local</file>. Packages must
5759 not create sub-directories in the
5760 directory <file>/usr/local</file> itself, except those
5761 listed in FHS, section 4.5. However, you may create
5762 directories below them as you wish. You must not remove
5763 any of the directories listed in 4.5, even if you created
5768 Since <file>/usr/local</file> can be mounted read-only from a
5769 remote server, these directories must be created and
5770 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5771 maintainer scripts and not be included in the
5772 <file>.deb</file> archive. These scripts must not fail if
5773 either of these operations fail.
5777 For example, the <tt>emacsen-common</tt> package could
5778 contain something like
5779 <example compact="compact">
5780 if [ ! -e /usr/local/share/emacs ]
5782 if mkdir /usr/local/share/emacs 2>/dev/null
5784 chown root:staff /usr/local/share/emacs
5785 chmod 2775 /usr/local/share/emacs
5789 in its <prgn>postinst</prgn> script, and
5790 <example compact="compact">
5791 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5792 rmdir /usr/local/share/emacs 2>/dev/null || true
5794 in the <prgn>prerm</prgn> script. (Note that this form is
5795 used to ensure that if the script is interrupted, the
5796 directory <file>/usr/local/share/emacs</file> will still be
5801 If you do create a directory in <file>/usr/local</file> for
5802 local additions to a package, you should ensure that
5803 settings in <file>/usr/local</file> take precedence over the
5804 equivalents in <file>/usr</file>.
5808 However, because <file>/usr/local</file> and its contents are
5809 for exclusive use of the local administrator, a package
5810 must not rely on the presence or absence of files or
5811 directories in <file>/usr/local</file> for normal operation.
5815 The <file>/usr/local</file> directory itself and all the
5816 subdirectories created by the package should (by default) have
5817 permissions 2775 (group-writable and set-group-id) and be
5818 owned by <tt>root:staff</tt>.
5823 <heading>The system-wide mail directory</heading>
5825 The system-wide mail directory
5826 is <file>/var/mail</file>. This directory is part of the
5827 base system and should not be owned by any particular mail
5828 agents. The use of the old
5829 location <file>/var/spool/mail</file> is deprecated, even
5830 though the spool may still be physically located there.
5836 <heading>Users and groups</heading>
5839 <heading>Introduction</heading>
5841 The Debian system can be configured to use either plain or
5846 Some user ids (UIDs) and group ids (GIDs) are reserved
5847 globally for use by certain packages. Because some
5848 packages need to include files which are owned by these
5849 users or groups, or need the ids compiled into binaries,
5850 these ids must be used on any Debian system only for the
5851 purpose for which they are allocated. This is a serious
5852 restriction, and we should avoid getting in the way of
5853 local administration policies. In particular, many sites
5854 allocate users and/or local system groups starting at 100.
5858 Apart from this we should have dynamically allocated ids,
5859 which should by default be arranged in some sensible
5860 order, but the behavior should be configurable.
5864 Packages other than <tt>base-passwd</tt> must not modify
5865 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5866 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5871 <heading>UID and GID classes</heading>
5873 The UID and GID numbers are divided into classes as
5879 Globally allocated by the Debian project, the same
5880 on every Debian system. These ids will appear in
5881 the <file>passwd</file> and <file>group</file> files of all
5882 Debian systems, new ids in this range being added
5883 automatically as the <tt>base-passwd</tt> package is
5888 Packages which need a single statically allocated
5889 uid or gid should use one of these; their
5890 maintainers should ask the <tt>base-passwd</tt>
5898 Dynamically allocated system users and groups.
5899 Packages which need a user or group, but can have
5900 this user or group allocated dynamically and
5901 differently on each system, should use <tt>adduser
5902 --system</tt> to create the group and/or user.
5903 <prgn>adduser</prgn> will check for the existence of
5904 the user or group, and if necessary choose an unused
5905 id based on the ranges specified in
5906 <file>adduser.conf</file>.
5910 <tag>1000-59999:</tag>
5913 Dynamically allocated user accounts. By default
5914 <prgn>adduser</prgn> will choose UIDs and GIDs for
5915 user accounts in this range, though
5916 <file>adduser.conf</file> may be used to modify this
5921 <tag>60000-64999:</tag>
5924 Globally allocated by the Debian project, but only
5925 created on demand. The ids are allocated centrally
5926 and statically, but the actual accounts are only
5927 created on users' systems on demand.
5931 These ids are for packages which are obscure or
5932 which require many statically-allocated ids. These
5933 packages should check for and create the accounts in
5934 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5935 <prgn>adduser</prgn> if it has this facility) if
5936 necessary. Packages which are likely to require
5937 further allocations should have a "hole" left after
5938 them in the allocation, to give them room to
5943 <tag>65000-65533:</tag>
5951 User <tt>nobody</tt>. The corresponding gid refers
5952 to the group <tt>nogroup</tt>.
5959 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5960 not</em> be used, because it is the error return
5969 <sect id="sysvinit">
5970 <heading>System run levels and <file>init.d</file> scripts</heading>
5972 <sect1 id="/etc/init.d">
5973 <heading>Introduction</heading>
5976 The <file>/etc/init.d</file> directory contains the scripts
5977 executed by <prgn>init</prgn> at boot time and when the
5978 init state (or "runlevel") is changed (see <manref
5979 name="init" section="8">).
5983 There are at least two different, yet functionally
5984 equivalent, ways of handling these scripts. For the sake
5985 of simplicity, this document describes only the symbolic
5986 link method. However, it must not be assumed by maintainer
5987 scripts that this method is being used, and any automated
5988 manipulation of the various runlevel behaviors by
5989 maintainer scripts must be performed using
5990 <prgn>update-rc.d</prgn> as described below and not by
5991 manually installing or removing symlinks. For information
5992 on the implementation details of the other method,
5993 implemented in the <tt>file-rc</tt> package, please refer
5994 to the documentation of that package.
5998 These scripts are referenced by symbolic links in the
5999 <file>/etc/rc<var>n</var>.d</file> directories. When changing
6000 runlevels, <prgn>init</prgn> looks in the directory
6001 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
6002 execute, where <tt><var>n</var></tt> is the runlevel that
6003 is being changed to, or <tt>S</tt> for the boot-up
6008 The names of the links all have the form
6009 <file>S<var>mm</var><var>script</var></file> or
6010 <file>K<var>mm</var><var>script</var></file> where
6011 <var>mm</var> is a two-digit number and <var>script</var>
6012 is the name of the script (this should be the same as the
6013 name of the actual script in <file>/etc/init.d</file>).
6017 When <prgn>init</prgn> changes runlevel first the targets
6018 of the links whose names start with a <tt>K</tt> are
6019 executed, each with the single argument <tt>stop</tt>,
6020 followed by the scripts prefixed with an <tt>S</tt>, each
6021 with the single argument <tt>start</tt>. (The links are
6022 those in the <file>/etc/rc<var>n</var>.d</file> directory
6023 corresponding to the new runlevel.) The <tt>K</tt> links
6024 are responsible for killing services and the <tt>S</tt>
6025 link for starting services upon entering the runlevel.
6029 For example, if we are changing from runlevel 2 to
6030 runlevel 3, init will first execute all of the <tt>K</tt>
6031 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
6032 all of the <tt>S</tt> prefixed scripts in that directory.
6033 The links starting with <tt>K</tt> will cause the
6034 referred-to file to be executed with an argument of
6035 <tt>stop</tt>, and the <tt>S</tt> links with an argument
6040 The two-digit number <var>mm</var> is used to determine
6041 the order in which to run the scripts: low-numbered links
6042 have their scripts run first. For example, the
6043 <tt>K20</tt> scripts will be executed before the
6044 <tt>K30</tt> scripts. This is used when a certain service
6045 must be started before another. For example, the name
6046 server <prgn>bind</prgn> might need to be started before
6047 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
6048 can set up its access lists. In this case, the script
6049 that starts <prgn>bind</prgn> would have a lower number
6050 than the script that starts <prgn>inn</prgn> so that it
6052 <example compact="compact">
6059 The two runlevels 0 (halt) and 6 (reboot) are slightly
6060 different. In these runlevels, the links with an
6061 <tt>S</tt> prefix are still called after those with a
6062 <tt>K</tt> prefix, but they too are called with the single
6063 argument <tt>stop</tt>.
6067 <sect1 id="writing-init">
6068 <heading>Writing the scripts</heading>
6071 Packages that include daemons for system services should
6072 place scripts in <file>/etc/init.d</file> to start or stop
6073 services at boot time or during a change of runlevel.
6074 These scripts should be named
6075 <file>/etc/init.d/<var>package</var></file>, and they should
6076 accept one argument, saying what to do:
6079 <tag><tt>start</tt></tag>
6080 <item>start the service,</item>
6082 <tag><tt>stop</tt></tag>
6083 <item>stop the service,</item>
6085 <tag><tt>restart</tt></tag>
6086 <item>stop and restart the service if it's already running,
6087 otherwise start the service</item>
6089 <tag><tt>reload</tt></tag>
6090 <item><p>cause the configuration of the service to be
6091 reloaded without actually stopping and restarting
6094 <tag><tt>force-reload</tt></tag>
6095 <item>cause the configuration to be reloaded if the
6096 service supports this, otherwise restart the
6100 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
6101 <tt>force-reload</tt> options should be supported by all
6102 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
6107 The <file>init.d</file> scripts must ensure that they will
6108 behave sensibly (i.e., returning success and not starting
6109 multiple copies of a service) if invoked with <tt>start</tt>
6110 when the service is already running, or with <tt>stop</tt>
6111 when it isn't, and that they don't kill unfortunately-named
6112 user processes. The best way to achieve this is usually to
6113 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
6118 Be careful of using <tt>set -e</tt> in <file>init.d</file>
6119 scripts. Writing correct <file>init.d</file> scripts requires
6120 accepting various error exit statuses when daemons are already
6121 running or already stopped without aborting
6122 the <file>init.d</file> script, and common <file>init.d</file>
6123 function libraries are not safe to call with <tt>set -e</tt>
6125 <tt>/lib/lsb/init-functions</tt>, which assists in writing
6126 LSB-compliant init scripts, may fail if <tt>set -e</tt> is
6127 in effect and echoing status messages to the console fails,
6129 </footnote>. For <tt>init.d</tt> scripts, it's often easier
6130 to not use <tt>set -e</tt> and instead check the result of
6131 each command separately.
6135 If a service reloads its configuration automatically (as
6136 in the case of <prgn>cron</prgn>, for example), the
6137 <tt>reload</tt> option of the <file>init.d</file> script
6138 should behave as if the configuration has been reloaded
6143 The <file>/etc/init.d</file> scripts must be treated as
6144 configuration files, either (if they are present in the
6145 package, that is, in the .deb file) by marking them as
6146 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
6147 by managing them correctly in the maintainer scripts (see
6148 <ref id="config-files">). This is important since we want
6149 to give the local system administrator the chance to adapt
6150 the scripts to the local system, e.g., to disable a
6151 service without de-installing the package, or to specify
6152 some special command line options when starting a service,
6153 while making sure their changes aren't lost during the next
6158 These scripts should not fail obscurely when the
6159 configuration files remain but the package has been
6160 removed, as configuration files remain on the system after
6161 the package has been removed. Only when <prgn>dpkg</prgn>
6162 is executed with the <tt>--purge</tt> option will
6163 configuration files be removed. In particular, as the
6164 <file>/etc/init.d/<var>package</var></file> script itself is
6165 usually a <tt>conffile</tt>, it will remain on the system
6166 if the package is removed but not purged. Therefore, you
6167 should include a <tt>test</tt> statement at the top of the
6169 <example compact="compact">
6170 test -f <var>program-executed-later-in-script</var> || exit 0
6175 Often there are some variables in the <file>init.d</file>
6176 scripts whose values control the behavior of the scripts,
6177 and which a system administrator is likely to want to
6178 change. As the scripts themselves are frequently
6179 <tt>conffile</tt>s, modifying them requires that the
6180 administrator merge in their changes each time the package
6181 is upgraded and the <tt>conffile</tt> changes. To ease
6182 the burden on the system administrator, such configurable
6183 values should not be placed directly in the script.
6184 Instead, they should be placed in a file in
6185 <file>/etc/default</file>, which typically will have the same
6186 base name as the <file>init.d</file> script. This extra file
6187 should be sourced by the script when the script runs. It
6188 must contain only variable settings and comments in SUSv3
6189 <prgn>sh</prgn> format. It may either be a
6190 <tt>conffile</tt> or a configuration file maintained by
6191 the package maintainer scripts. See <ref id="config-files">
6196 To ensure that vital configurable values are always
6197 available, the <file>init.d</file> script should set default
6198 values for each of the shell variables it uses, either
6199 before sourcing the <file>/etc/default/</file> file or
6200 afterwards using something like the <tt>:
6201 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6202 script must behave sensibly and not fail if the
6203 <file>/etc/default</file> file is deleted.
6207 <file>/var/run</file> and <file>/var/lock</file> may be mounted
6208 as temporary filesystems<footnote>
6209 For example, using the <tt>RAMRUN</tt> and <tt>RAMLOCK</tt>
6210 options in <file>/etc/default/rcS</file>.
6211 </footnote>, so the <file>init.d</file> scripts must handle this
6212 correctly. This will typically amount to creating any required
6213 subdirectories dynamically when the <file>init.d</file> script
6214 is run, rather than including them in the package and relying on
6215 <prgn>dpkg</prgn> to create them.
6220 <heading>Interfacing with the initscript system</heading>
6223 Maintainers should use the abstraction layer provided by
6224 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6225 programs to deal with initscripts in their packages'
6226 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6227 and <prgn>postrm</prgn>.
6231 Directly managing the /etc/rc?.d links and directly
6232 invoking the <file>/etc/init.d/</file> initscripts should
6233 be done only by packages providing the initscript
6234 subsystem (such as <prgn>sysv-rc</prgn> and
6235 <prgn>file-rc</prgn>).
6239 <heading>Managing the links</heading>
6242 The program <prgn>update-rc.d</prgn> is provided for
6243 package maintainers to arrange for the proper creation and
6244 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6245 or their functional equivalent if another method is being
6246 used. This may be used by maintainers in their packages'
6247 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6251 You must not include any <file>/etc/rc<var>n</var>.d</file>
6252 symbolic links in the actual archive or manually create or
6253 remove the symbolic links in maintainer scripts; you must
6254 use the <prgn>update-rc.d</prgn> program instead. (The
6255 former will fail if an alternative method of maintaining
6256 runlevel information is being used.) You must not include
6257 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6258 in the archive either. (Only the <tt>sysvinit</tt>
6263 By default <prgn>update-rc.d</prgn> will start services in
6264 each of the multi-user state runlevels (2, 3, 4, and 5)
6265 and stop them in the halt runlevel (0), the single-user
6266 runlevel (1) and the reboot runlevel (6). The system
6267 administrator will have the opportunity to customize
6268 runlevels by simply adding, moving, or removing the
6269 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6270 symbolic links are being used, or by modifying
6271 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6276 To get the default behavior for your package, put in your
6277 <prgn>postinst</prgn> script
6278 <example compact="compact">
6279 update-rc.d <var>package</var> defaults
6281 and in your <prgn>postrm</prgn>
6282 <example compact="compact">
6283 if [ "$1" = purge ]; then
6284 update-rc.d <var>package</var> remove
6286 </example>. Note that if your package changes runlevels
6287 or priority, you may have to remove and recreate the links,
6288 since otherwise the old links may persist. Refer to the
6289 documentation of <prgn>update-rc.d</prgn>.
6293 This will use a default sequence number of 20. If it does
6294 not matter when or in which order the <file>init.d</file>
6295 script is run, use this default. If it does, then you
6296 should talk to the maintainer of the <prgn>sysvinit</prgn>
6297 package or post to <tt>debian-devel</tt>, and they will
6298 help you choose a number.
6302 For more information about using <tt>update-rc.d</tt>,
6303 please consult its man page <manref name="update-rc.d"
6309 <heading>Running initscripts</heading>
6311 The program <prgn>invoke-rc.d</prgn> is provided to make
6312 it easier for package maintainers to properly invoke an
6313 initscript, obeying runlevel and other locally-defined
6314 constraints that might limit a package's right to start,
6315 stop and otherwise manage services. This program may be
6316 used by maintainers in their packages' scripts.
6320 The package maintainer scripts must use
6321 <prgn>invoke-rc.d</prgn> to invoke the
6322 <file>/etc/init.d/*</file> initscripts, instead of
6323 calling them directly.
6327 By default, <prgn>invoke-rc.d</prgn> will pass any
6328 action requests (start, stop, reload, restart...) to the
6329 <file>/etc/init.d</file> script, filtering out requests
6330 to start or restart a service out of its intended
6335 Most packages will simply need to change:
6336 <example compact="compact">/etc/init.d/<package>
6337 <action></example> in their <prgn>postinst</prgn>
6338 and <prgn>prerm</prgn> scripts to:
6339 <example compact="compact">
6340 if which invoke-rc.d >/dev/null 2>&1; then
6341 invoke-rc.d <var>package</var> <action>
6343 /etc/init.d/<var>package</var> <action>
6349 A package should register its initscript services using
6350 <prgn>update-rc.d</prgn> before it tries to invoke them
6351 using <prgn>invoke-rc.d</prgn>. Invocation of
6352 unregistered services may fail.
6356 For more information about using
6357 <prgn>invoke-rc.d</prgn>, please consult its man page
6358 <manref name="invoke-rc.d" section="8">.
6364 <heading>Boot-time initialization</heading>
6367 There used to be another directory, <file>/etc/rc.boot</file>,
6368 which contained scripts which were run once per machine
6369 boot. This has been deprecated in favour of links from
6370 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6371 described in <ref id="/etc/init.d">. Packages must not
6372 place files in <file>/etc/rc.boot</file>.
6377 <heading>Example</heading>
6380 An example on which you can base your
6381 <file>/etc/init.d</file> scripts is found in
6382 <file>/etc/init.d/skeleton</file>.
6389 <heading>Console messages from <file>init.d</file> scripts</heading>
6392 This section describes the formats to be used for messages
6393 written to standard output by the <file>/etc/init.d</file>
6394 scripts. The intent is to improve the consistency of
6395 Debian's startup and shutdown look and feel. For this
6396 reason, please look very carefully at the details. We want
6397 the messages to have the same format in terms of wording,
6398 spaces, punctuation and case of letters.
6402 Here is a list of overall rules that should be used for
6403 messages generated by <file>/etc/init.d</file> scripts.
6409 The message should fit in one line (fewer than 80
6410 characters), start with a capital letter and end with
6411 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6415 If the script is performing some time consuming task in
6416 the background (not merely starting or stopping a
6417 program, for instance), an ellipsis (three dots:
6418 <tt>...</tt>) should be output to the screen, with no
6419 leading or tailing whitespace or line feeds.
6423 The messages should appear as if the computer is telling
6424 the user what it is doing (politely :-), but should not
6425 mention "it" directly. For example, instead of:
6426 <example compact="compact">
6427 I'm starting network daemons: nfsd mountd.
6429 the message should say
6430 <example compact="compact">
6431 Starting network daemons: nfsd mountd.
6438 <tt>init.d</tt> script should use the following standard
6439 message formats for the situations enumerated below.
6445 <p>When daemons are started</p>
6448 If the script starts one or more daemons, the output
6449 should look like this (a single line, no leading
6451 <example compact="compact">
6452 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6454 The <var>description</var> should describe the
6455 subsystem the daemon or set of daemons are part of,
6456 while <var>daemon-1</var> up to <var>daemon-n</var>
6457 denote each daemon's name (typically the file name of
6462 For example, the output of <file>/etc/init.d/lpd</file>
6464 <example compact="compact">
6465 Starting printer spooler: lpd.
6470 This can be achieved by saying
6471 <example compact="compact">
6472 echo -n "Starting printer spooler: lpd"
6473 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6476 in the script. If there are more than one daemon to
6477 start, the output should look like this:
6478 <example compact="compact">
6479 echo -n "Starting remote file system services:"
6480 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6481 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6482 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6485 This makes it possible for the user to see what is
6486 happening and when the final daemon has been started.
6487 Care should be taken in the placement of white spaces:
6488 in the example above the system administrators can
6489 easily comment out a line if they don't want to start
6490 a specific daemon, while the displayed message still
6496 <p>When a system parameter is being set</p>
6499 If you have to set up different system parameters
6500 during the system boot, you should use this format:
6501 <example compact="compact">
6502 Setting <var>parameter</var> to "<var>value</var>".
6507 You can use a statement such as the following to get
6509 <example compact="compact">
6510 echo "Setting DNS domainname to \"$domainname\"."
6515 Note that the same symbol (<tt>"</tt>) <!-- " --> is used
6516 for the left and right quotation marks. A grave accent
6517 (<tt>`</tt>) is not a quote character; neither is an
6518 apostrophe (<tt>'</tt>).
6523 <p>When a daemon is stopped or restarted</p>
6526 When you stop or restart a daemon, you should issue a
6527 message identical to the startup message, except that
6528 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6529 or <tt>Restarting</tt> respectively.
6533 For example, stopping the printer daemon will look like
6535 <example compact="compact">
6536 Stopping printer spooler: lpd.
6542 <p>When something is executed</p>
6545 There are several examples where you have to run a
6546 program at system startup or shutdown to perform a
6547 specific task, for example, setting the system's clock
6548 using <prgn>netdate</prgn> or killing all processes
6549 when the system shuts down. Your message should look
6551 <example compact="compact">
6552 Doing something very useful...done.
6554 You should print the <tt>done.</tt> immediately after
6555 the job has been completed, so that the user is
6556 informed why they have to wait. You can get this
6558 <example compact="compact">
6559 echo -n "Doing something very useful..."
6568 <p>When the configuration is reloaded</p>
6571 When a daemon is forced to reload its configuration
6572 files you should use the following format:
6573 <example compact="compact">
6574 Reloading <var>description</var> configuration...done.
6576 where <var>description</var> is the same as in the
6577 daemon starting message.
6585 <heading>Cron jobs</heading>
6588 Packages must not modify the configuration file
6589 <file>/etc/crontab</file>, and they must not modify the files in
6590 <file>/var/spool/cron/crontabs</file>.</p>
6593 If a package wants to install a job that has to be executed
6594 via cron, it should place a file with the name of the
6595 package in one or more of the following directories:
6596 <example compact="compact">
6602 As these directory names imply, the files within them are
6603 executed on an hourly, daily, weekly, or monthly basis,
6604 respectively. The exact times are listed in
6605 <file>/etc/crontab</file>.</p>
6608 All files installed in any of these directories must be
6609 scripts (e.g., shell scripts or Perl scripts) so that they
6610 can easily be modified by the local system administrator.
6611 In addition, they must be treated as configuration files.
6615 If a certain job has to be executed at some other frequency or
6616 at a specific time, the package should install a file
6617 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6618 same syntax as <file>/etc/crontab</file> and is processed by
6619 <prgn>cron</prgn> automatically. The file must also be
6620 treated as a configuration file. (Note that entries in the
6621 <file>/etc/cron.d</file> directory are not handled by
6622 <prgn>anacron</prgn>. Thus, you should only use this
6623 directory for jobs which may be skipped if the system is not
6626 Unlike <file>crontab</file> files described in the IEEE Std
6627 1003.1-2008 (POSIX.1) available from
6628 <url id="http://www.opengroup.org/onlinepubs/9699919799/"
6629 name="The Open Group">, the files in
6630 <file>/etc/cron.d</file> and the file
6631 <file>/etc/crontab</file> have seven fields; namely:
6633 <item>Minute [0,59]</item>
6634 <item>Hour [0,23]</item>
6635 <item>Day of the month [1,31]</item>
6636 <item>Month of the year [1,12]</item>
6637 <item>Day of the week ([0,6] with 0=Sunday)</item>
6638 <item>Username</item>
6639 <item>Command to be run</item>
6641 Ranges of numbers are allowed. Ranges are two numbers
6642 separated with a hyphen. The specified range is inclusive.
6643 Lists are allowed. A list is a set of numbers (or ranges)
6644 separated by commas. Step values can be used in conjunction
6649 The scripts or <tt>crontab</tt> entries in these directories should
6650 check if all necessary programs are installed before they
6651 try to execute them. Otherwise, problems will arise when a
6652 package was removed but not purged since configuration files
6653 are kept on the system in this situation.
6657 Any <tt>cron</tt> daemon must provide
6658 <file>/usr/bin/crontab</file> and support normal
6659 <tt>crontab</tt> entries as specified in POSIX. The daemon
6660 must also support names for days and months, ranges, and
6661 step values. It has to support <file>/etc/crontab</file>,
6662 and correctly execute the scripts in
6663 <file>/etc/cron.d</file>. The daemon must also correctly
6665 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>.
6670 <heading>Menus</heading>
6673 The Debian <tt>menu</tt> package provides a standard
6674 interface between packages providing applications and
6675 <em>menu programs</em> (either X window managers or
6676 text-based menu programs such as <prgn>pdmenu</prgn>).
6680 All packages that provide applications that need not be
6681 passed any special command line arguments for normal
6682 operation should register a menu entry for those
6683 applications, so that users of the <tt>menu</tt> package
6684 will automatically get menu entries in their window
6685 managers, as well in shells like <tt>pdmenu</tt>.
6689 Menu entries should follow the current menu policy.
6693 The menu policy can be found in the <tt>menu-policy</tt>
6694 files in the <tt>debian-policy</tt> package.
6695 It is also available from the Debian web mirrors at
6696 <tt><url name="/doc/packaging-manuals/menu-policy/"
6697 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6701 Please also refer to the <em>Debian Menu System</em>
6702 documentation that comes with the <package>menu</package>
6703 package for information about how to register your
6709 <heading>Multimedia handlers</heading>
6712 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6713 is a mechanism for encoding files and data streams and
6714 providing meta-information about them, in particular their
6715 type (e.g. audio or video) and format (e.g. PNG, HTML,
6720 Registration of MIME type handlers allows programs like mail
6721 user agents and web browsers to invoke these handlers to
6722 view, edit or display MIME types they don't support directly.
6726 Packages which provide the ability to view/show/play,
6727 compose, edit or print MIME types should register themselves
6728 as such following the current MIME support policy.
6732 The MIME support policy can be found in the <tt>mime-policy</tt>
6733 files in the <tt>debian-policy</tt> package.
6734 It is also available from the Debian web mirrors at
6735 <tt><url name="/doc/packaging-manuals/mime-policy/"
6736 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6742 <heading>Keyboard configuration</heading>
6745 To achieve a consistent keyboard configuration so that all
6746 applications interpret a keyboard event the same way, all
6747 programs in the Debian distribution must be configured to
6748 comply with the following guidelines.
6752 The following keys must have the specified interpretations:
6755 <tag><tt><--</tt></tag>
6756 <item>delete the character to the left of the cursor</item>
6758 <tag><tt>Delete</tt></tag>
6759 <item>delete the character to the right of the cursor</item>
6761 <tag><tt>Control+H</tt></tag>
6762 <item>emacs: the help prefix</item>
6765 The interpretation of any keyboard events should be
6766 independent of the terminal that is used, be it a virtual
6767 console, an X terminal emulator, an rlogin/telnet session,
6772 The following list explains how the different programs
6773 should be set up to achieve this:
6779 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6783 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6787 X translations are set up to make
6788 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6789 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6790 is the vt220 escape code for the "delete character"
6791 key). This must be done by loading the X resources
6792 using <prgn>xrdb</prgn> on all local X displays, not
6793 using the application defaults, so that the
6794 translation resources used correspond to the
6795 <prgn>xmodmap</prgn> settings.
6799 The Linux console is configured to make
6800 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6801 generate <tt>ESC [ 3 ~</tt>.
6805 X applications are configured so that <tt><</tt>
6806 deletes left, and <tt>Delete</tt> deletes right. Motif
6807 applications already work like this.
6811 Terminals should have <tt>stty erase ^?</tt> .
6815 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6816 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6817 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6821 Emacs is programmed to map <tt>KB_Backspace</tt> or
6822 the <tt>stty erase</tt> character to
6823 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6824 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6825 <tt>^H</tt> to <tt>help</tt> as always.
6829 Other applications use the <tt>stty erase</tt>
6830 character and <tt>kdch1</tt> for the two delete keys,
6831 with ASCII DEL being "delete previous character" and
6832 <tt>kdch1</tt> being "delete character under
6840 This will solve the problem except for the following
6847 Some terminals have a <tt><--</tt> key that cannot
6848 be made to produce anything except <tt>^H</tt>. On
6849 these terminals Emacs help will be unavailable on
6850 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6851 character takes precedence in Emacs, and has been set
6852 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6853 available) can be used instead.
6857 Some operating systems use <tt>^H</tt> for <tt>stty
6858 erase</tt>. However, modern telnet versions and all
6859 rlogin versions propagate <tt>stty</tt> settings, and
6860 almost all UNIX versions honour <tt>stty erase</tt>.
6861 Where the <tt>stty</tt> settings are not propagated
6862 correctly, things can be made to work by using
6863 <tt>stty</tt> manually.
6867 Some systems (including previous Debian versions) use
6868 <prgn>xmodmap</prgn> to arrange for both
6869 <tt><--</tt> and <tt>Delete</tt> to generate
6870 <tt>KB_Delete</tt>. We can change the behavior of
6871 their X clients using the same X resources that we use
6872 to do it for our own clients, or configure our clients
6873 using their resources when things are the other way
6874 around. On displays configured like this
6875 <tt>Delete</tt> will not work, but <tt><--</tt>
6880 Some operating systems have different <tt>kdch1</tt>
6881 settings in their <tt>terminfo</tt> database for
6882 <tt>xterm</tt> and others. On these systems the
6883 <tt>Delete</tt> key will not work correctly when you
6884 log in from a system conforming to our policy, but
6885 <tt><--</tt> will.
6892 <heading>Environment variables</heading>
6895 A program must not depend on environment variables to get
6896 reasonable defaults. (That's because these environment
6897 variables would have to be set in a system-wide
6898 configuration file like <file>/etc/profile</file>, which is not
6899 supported by all shells.)
6903 If a program usually depends on environment variables for its
6904 configuration, the program should be changed to fall back to
6905 a reasonable default configuration if these environment
6906 variables are not present. If this cannot be done easily
6907 (e.g., if the source code of a non-free program is not
6908 available), the program must be replaced by a small
6909 "wrapper" shell script which sets the environment variables
6910 if they are not already defined, and calls the original program.
6914 Here is an example of a wrapper script for this purpose:
6916 <example compact="compact">
6918 BAR=${BAR:-/var/lib/fubar}
6920 exec /usr/lib/foo/foo "$@"
6925 Furthermore, as <file>/etc/profile</file> is a configuration
6926 file of the <prgn>base-files</prgn> package, other packages must
6927 not put any environment variables or other commands into that
6932 <sect id="doc-base">
6933 <heading>Registering Documents using doc-base</heading>
6936 The <package>doc-base</package> package implements a
6937 flexible mechanism for handling and presenting
6938 documentation. The recommended practice is for every Debian
6939 package that provides online documentation (other than just
6940 manual pages) to register these documents with
6941 <package>doc-base</package> by installing a
6942 <package>doc-base</package> control file via the
6943 <prgn/install-docs/ script at installation time and
6944 de-register the manuals again when the package is removed.
6947 Please refer to the documentation that comes with the
6948 <package>doc-base</package> package for information and
6957 <heading>Files</heading>
6960 <heading>Binaries</heading>
6963 Two different packages must not install programs with
6964 different functionality but with the same filenames. (The
6965 case of two programs having the same functionality but
6966 different implementations is handled via "alternatives" or
6967 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6968 <ref id="conflicts"> respectively.) If this case happens,
6969 one of the programs must be renamed. The maintainers should
6970 report this to the <tt>debian-devel</tt> mailing list and
6971 try to find a consensus about which program will have to be
6972 renamed. If a consensus cannot be reached, <em>both</em>
6973 programs must be renamed.
6977 By default, when a package is being built, any binaries
6978 created should include debugging information, as well as
6979 being compiled with optimization. You should also turn on
6980 as many reasonable compilation warnings as possible; this
6981 makes life easier for porters, who can then look at build
6982 logs for possible problems. For the C programming language,
6983 this means the following compilation parameters should be
6985 <example compact="compact">
6987 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6989 INSTALL = install -s # (or use strip on the files in debian/tmp)
6994 Note that by default all installed binaries should be stripped,
6995 either by using the <tt>-s</tt> flag to
6996 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6997 the binaries after they have been copied into
6998 <file>debian/tmp</file> but before the tree is made into a
7003 Although binaries in the build tree should be compiled with
7004 debugging information by default, it can often be difficult to
7005 debug programs if they are also subjected to compiler
7006 optimization. For this reason, it is recommended to support the
7007 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
7008 (see <ref id="debianrules-options">). This variable can contain
7009 several flags to change how a package is compiled and built.
7013 It is up to the package maintainer to decide what
7014 compilation options are best for the package. Certain
7015 binaries (such as computationally-intensive programs) will
7016 function better with certain flags (<tt>-O3</tt>, for
7017 example); feel free to use them. Please use good judgment
7018 here. Don't use flags for the sake of it; only use them
7019 if there is good reason to do so. Feel free to override
7020 the upstream author's ideas about which compilation
7021 options are best: they are often inappropriate for our
7027 <sect id="libraries">
7028 <heading>Libraries</heading>
7031 If the package is <strong>architecture: any</strong>, then
7032 the shared library compilation and linking flags must have
7033 <tt>-fPIC</tt>, or the package shall not build on some of
7034 the supported architectures<footnote>
7036 If you are using GCC, <tt>-fPIC</tt> produces code with
7037 relocatable position independent code, which is required for
7038 most architectures to create a shared library, with i386 and
7039 perhaps some others where non position independent code is
7040 permitted in a shared library.
7043 Position independent code may have a performance penalty,
7044 especially on <tt>i386</tt>. However, in most cases the
7045 speed penalty must be measured against the memory wasted on
7046 the few architectures where non position independent code is
7049 </footnote>. Any exception to this rule must be discussed on
7050 the mailing list <em>debian-devel@lists.debian.org</em>, and
7051 a rough consensus obtained. The reasons for not compiling
7052 with <tt>-fPIC</tt> flag must be recorded in the file
7053 <tt>README.Debian</tt>, and care must be taken to either
7054 restrict the architecture or arrange for <tt>-fPIC</tt> to
7055 be used on architectures where it is required.<footnote>
7057 Some of the reasons why this might be required is if the
7058 library contains hand crafted assembly code that is not
7059 relocatable, the speed penalty is excessive for compute
7060 intensive libs, and similar reasons.
7065 As to the static libraries, the common case is not to have
7066 relocatable code, since there is no benefit, unless in specific
7067 cases; therefore the static version must not be compiled
7068 with the <tt>-fPIC</tt> flag. Any exception to this rule
7069 should be discussed on the mailing list
7070 <em>debian-devel@lists.debian.org</em>, and the reasons for
7071 compiling with the <tt>-fPIC</tt> flag must be recorded in
7072 the file <tt>README.Debian</tt>. <footnote>
7074 Some of the reasons for linking static libraries with
7075 the <tt>-fPIC</tt> flag are if, for example, one needs a
7076 Perl API for a library that is under rapid development,
7077 and has an unstable API, so shared libraries are
7078 pointless at this phase of the library's development. In
7079 that case, since Perl needs a library with relocatable
7080 code, it may make sense to create a static library with
7081 relocatable code. Another reason cited is if you are
7082 distilling various libraries into a common shared
7083 library, like <tt>mklibs</tt> does in the Debian
7089 In other words, if both a shared and a static library is
7090 being built, each source unit (<tt>*.c</tt>, for example,
7091 for C files) will need to be compiled twice, for the normal
7095 You must specify the gcc option <tt>-D_REENTRANT</tt>
7096 when building a library (either static or shared) to make
7097 the library compatible with LinuxThreads.
7101 Although not enforced by the build tools, shared libraries
7102 must be linked against all libraries that they use symbols from
7103 in the same way that binaries are. This ensures the correct
7104 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
7105 system and guarantees that all libraries can be safely opened
7106 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
7107 option <tt>-Wl,-z,defs</tt> when building a shared library.
7108 Since this option enforces symbol resolution at build time,
7109 a missing library reference will be caught early as a fatal
7114 All installed shared libraries should be stripped with
7115 <example compact="compact">
7116 strip --strip-unneeded <var>your-lib</var>
7118 (The option <tt>--strip-unneeded</tt> makes
7119 <prgn>strip</prgn> remove only the symbols which aren't
7120 needed for relocation processing.) Shared libraries can
7121 function perfectly well when stripped, since the symbols for
7122 dynamic linking are in a separate part of the ELF object
7124 You might also want to use the options
7125 <tt>--remove-section=.comment</tt> and
7126 <tt>--remove-section=.note</tt> on both shared libraries
7127 and executables, and <tt>--strip-debug</tt> on static
7133 Note that under some circumstances it may be useful to
7134 install a shared library unstripped, for example when
7135 building a separate package to support debugging.
7139 Shared object files (often <file>.so</file> files) that are not
7140 public libraries, that is, they are not meant to be linked
7141 to by third party executables (binaries of other packages),
7142 should be installed in subdirectories of the
7143 <file>/usr/lib</file> directory. Such files are exempt from the
7144 rules that govern ordinary shared libraries, except that
7145 they must not be installed executable and should be
7147 A common example are the so-called "plug-ins",
7148 internal shared objects that are dynamically loaded by
7149 programs using <manref name="dlopen" section="3">.
7154 An ever increasing number of packages are using
7155 <prgn>libtool</prgn> to do their linking. The latest GNU
7156 libtools (>= 1.3a) can take advantage of the metadata in the
7157 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
7158 files). The main advantage of <prgn>libtool</prgn>'s
7159 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
7160 store and subsequently access metadata with respect to the
7161 libraries it builds. <prgn>libtool</prgn> will search for
7162 those files, which contain a lot of useful information about
7163 a library (such as library dependency information for static
7164 linking). Also, they're <em>essential</em> for programs
7165 using <tt>libltdl</tt>.<footnote>
7166 Although <prgn>libtool</prgn> is fully capable of
7167 linking against shared libraries which don't have
7168 <tt>.la</tt> files, as it is a mere shell script it can
7169 add considerably to the build time of a
7170 <prgn>libtool</prgn>-using package if that shell script
7171 has to derive all this information from first principles
7172 for each library every time it is linked. With the
7173 advent of <prgn>libtool</prgn> version 1.4 (and to a
7174 lesser extent <prgn>libtool</prgn> version 1.3), the
7175 <file>.la</file> files also store information about
7176 inter-library dependencies which cannot necessarily be
7177 derived after the <file>.la</file> file is deleted.
7182 Packages that use <prgn>libtool</prgn> to create shared
7183 libraries should include the <file>.la</file> files in the
7184 <tt>-dev</tt> package, unless the package relies on
7185 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
7186 the <tt>.la</tt> files must go in the run-time library
7191 You must make sure that you use only released versions of
7192 shared libraries to build your packages; otherwise other
7193 users will not be able to run your binaries
7194 properly. Producing source packages that depend on
7195 unreleased compilers is also usually a bad
7202 <heading>Shared libraries</heading>
7204 This section has moved to <ref id="sharedlibs">.
7210 <heading>Scripts</heading>
7213 All command scripts, including the package maintainer
7214 scripts inside the package and used by <prgn>dpkg</prgn>,
7215 should have a <tt>#!</tt> line naming the shell to be used
7220 In the case of Perl scripts this should be
7221 <tt>#!/usr/bin/perl</tt>.
7225 When scripts are installed into a directory in the system
7226 PATH, the script name should not include an extension such
7227 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7228 language currently used to implement it.
7231 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>) other than
7232 <file>init.d</file> scripts should almost certainly start
7233 with <tt>set -e</tt> so that errors are detected.
7234 <file>init.d</file> scripts are something of a special case, due
7235 to how frequently they need to call commands that are allowed to
7236 fail, and it may instead be easier to check the exit status of
7237 commands directly. See <ref id="writing-init"> for more
7238 information about writing <file>init.d</file> scripts.
7241 Every script should use <tt>set -e</tt> or check the exit status
7242 of <em>every</em> command.
7245 Scripts may assume that <file>/bin/sh</file> implements the
7246 SUSv3 Shell Command Language<footnote>
7247 Single UNIX Specification, version 3, which is also IEEE
7248 1003.1-2004 (POSIX), and is available on the World Wide Web
7249 from <url id="http://www.unix.org/version3/online.html"
7250 name="The Open Group"> after free
7251 registration.</footnote>
7252 plus the following additional features not mandated by
7254 These features are in widespread use in the Linux community
7255 and are implemented in all of bash, dash, and ksh, the most
7256 common shells users may wish to use as <file>/bin/sh</file>.
7259 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7260 must not generate a newline.</item>
7261 <item><tt>test</tt>, if implemented as a shell built-in, must
7262 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7264 <item><tt>local</tt> to create a scoped variable must be
7265 supported, including listing multiple variables in a single
7266 local command and assigning a value to a variable at the
7267 same time as localizing it. <tt>local</tt> may or
7268 may not preserve the variable value from an outer scope if
7269 no assignment is present. Uses such as:
7273 # ... use a, b, c, d ...
7276 must be supported and must set the value of <tt>c</tt> to
7280 If a shell script requires non-SUSv3 features from the shell
7281 interpreter other than those listed above, the appropriate shell
7282 must be specified in the first line of the script (e.g.,
7283 <tt>#!/bin/bash</tt>) and the package must depend on the package
7284 providing the shell (unless the shell package is marked
7285 "Essential", as in the case of <prgn>bash</prgn>).
7289 You may wish to restrict your script to SUSv3 features plus the
7290 above set when possible so that it may use <file>/bin/sh</file>
7291 as its interpreter. If your script works with <prgn>dash</prgn>
7292 (originally called <prgn>ash</prgn>), it probably complies with
7293 the above requirements, but if you are in doubt, use
7294 <file>/bin/bash</file>.
7298 Perl scripts should check for errors when making any
7299 system calls, including <tt>open</tt>, <tt>print</tt>,
7300 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7304 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7305 scripting languages. See <em>Csh Programming Considered
7306 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7307 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7308 If an upstream package comes with <prgn>csh</prgn> scripts
7309 then you must make sure that they start with
7310 <tt>#!/bin/csh</tt> and make your package depend on the
7311 <prgn>c-shell</prgn> virtual package.
7315 Any scripts which create files in world-writeable
7316 directories (e.g., in <file>/tmp</file>) must use a
7317 mechanism which will fail atomically if a file with the same
7318 name already exists.
7322 The Debian base system provides the <prgn>tempfile</prgn>
7323 and <prgn>mktemp</prgn> utilities for use by scripts for
7330 <heading>Symbolic links</heading>
7333 In general, symbolic links within a top-level directory
7334 should be relative, and symbolic links pointing from one
7335 top-level directory into another should be absolute. (A
7336 top-level directory is a sub-directory of the root
7337 directory <file>/</file>.)
7341 In addition, symbolic links should be specified as short as
7342 possible, i.e., link targets like <file>foo/../bar</file> are
7347 Note that when creating a relative link using
7348 <prgn>ln</prgn> it is not necessary for the target of the
7349 link to exist relative to the working directory you're
7350 running <prgn>ln</prgn> from, nor is it necessary to change
7351 directory to the directory where the link is to be made.
7352 Simply include the string that should appear as the target
7353 of the link (this will be a pathname relative to the
7354 directory in which the link resides) as the first argument
7359 For example, in your <prgn>Makefile</prgn> or
7360 <file>debian/rules</file>, you can do things like:
7361 <example compact="compact">
7362 ln -fs gcc $(prefix)/bin/cc
7363 ln -fs gcc debian/tmp/usr/bin/cc
7364 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7365 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7370 A symbolic link pointing to a compressed file should always
7371 have the same file extension as the referenced file. (For
7372 example, if a file <file>foo.gz</file> is referenced by a
7373 symbolic link, the filename of the link has to end with
7374 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7379 <heading>Device files</heading>
7382 Packages must not include device files or named pipes in the
7387 If a package needs any special device files that are not
7388 included in the base system, it must call
7389 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7390 after notifying the user<footnote>
7391 This notification could be done via a (low-priority)
7392 debconf message, or an echo (printf) statement.
7397 Packages must not remove any device files in the
7398 <prgn>postrm</prgn> or any other script. This is left to the
7399 system administrator.
7403 Debian uses the serial devices
7404 <file>/dev/ttyS*</file>. Programs using the old
7405 <file>/dev/cu*</file> devices should be changed to use
7406 <file>/dev/ttyS*</file>.
7410 Named pipes needed by the package must be created in
7411 the <prgn>postinst</prgn> script<footnote>
7412 It's better to use <prgn>mkfifo</prgn> rather
7413 than <prgn>mknod</prgn> to create named pipes so that
7414 automated checks for packages incorrectly creating device
7415 files with <prgn>mknod</prgn> won't have false positives.
7416 </footnote> and removed in
7417 the <prgn>prerm</prgn> or <prgn>postrm</prgn> script as
7422 <sect id="config-files">
7423 <heading>Configuration files</heading>
7426 <heading>Definitions</heading>
7430 <tag>configuration file</tag>
7432 A file that affects the operation of a program, or
7433 provides site- or host-specific information, or
7434 otherwise customizes the behavior of a program.
7435 Typically, configuration files are intended to be
7436 modified by the system administrator (if needed or
7437 desired) to conform to local policy or to provide
7438 more useful site-specific behavior.
7441 <tag><tt>conffile</tt></tag>
7443 A file listed in a package's <tt>conffiles</tt>
7444 file, and is treated specially by <prgn>dpkg</prgn>
7445 (see <ref id="configdetails">).
7451 The distinction between these two is important; they are
7452 not interchangeable concepts. Almost all
7453 <tt>conffile</tt>s are configuration files, but many
7454 configuration files are not <tt>conffiles</tt>.
7458 As noted elsewhere, <file>/etc/init.d</file> scripts,
7459 <file>/etc/default</file> files, scripts installed in
7460 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7461 configuration installed in <file>/etc/cron.d</file> must be
7462 treated as configuration files. In general, any script that
7463 embeds configuration information is de-facto a configuration
7464 file and should be treated as such.
7469 <heading>Location</heading>
7472 Any configuration files created or used by your package
7473 must reside in <file>/etc</file>. If there are several,
7474 consider creating a subdirectory of <file>/etc</file>
7475 named after your package.
7479 If your package creates or uses configuration files
7480 outside of <file>/etc</file>, and it is not feasible to modify
7481 the package to use <file>/etc</file> directly, put the files
7482 in <file>/etc</file> and create symbolic links to those files
7483 from the location that the package requires.
7488 <heading>Behavior</heading>
7491 Configuration file handling must conform to the following
7493 <list compact="compact">
7495 local changes must be preserved during a package
7499 configuration files must be preserved when the
7500 package is removed, and only deleted when the
7507 The easy way to achieve this behavior is to make the
7508 configuration file a <tt>conffile</tt>. This is
7509 appropriate only if it is possible to distribute a default
7510 version that will work for most installations, although
7511 some system administrators may choose to modify it. This
7512 implies that the default version will be part of the
7513 package distribution, and must not be modified by the
7514 maintainer scripts during installation (or at any other
7519 In order to ensure that local changes are preserved
7520 correctly, no package may contain or make hard links to
7521 conffiles.<footnote>
7522 Rationale: There are two problems with hard links.
7523 The first is that some editors break the link while
7524 editing one of the files, so that the two files may
7525 unwittingly become unlinked and different. The second
7526 is that <prgn>dpkg</prgn> might break the hard link
7527 while upgrading <tt>conffile</tt>s.
7532 The other way to do it is via the maintainer scripts. In
7533 this case, the configuration file must not be listed as a
7534 <tt>conffile</tt> and must not be part of the package
7535 distribution. If the existence of a file is required for
7536 the package to be sensibly configured it is the
7537 responsibility of the package maintainer to provide
7538 maintainer scripts which correctly create, update and
7539 maintain the file and remove it on purge. (See <ref
7540 id="maintainerscripts"> for more information.) These
7541 scripts must be idempotent (i.e., must work correctly if
7542 <prgn>dpkg</prgn> needs to re-run them due to errors
7543 during installation or removal), must cope with all the
7544 variety of ways <prgn>dpkg</prgn> can call maintainer
7545 scripts, must not overwrite or otherwise mangle the user's
7546 configuration without asking, must not ask unnecessary
7547 questions (particularly during upgrades), and must
7548 otherwise be good citizens.
7552 The scripts are not required to configure every possible
7553 option for the package, but only those necessary to get
7554 the package running on a given system. Ideally the
7555 sysadmin should not have to do any configuration other
7556 than that done (semi-)automatically by the
7557 <prgn>postinst</prgn> script.
7561 A common practice is to create a script called
7562 <file><var>package</var>-configure</file> and have the
7563 package's <prgn>postinst</prgn> call it if and only if the
7564 configuration file does not already exist. In certain
7565 cases it is useful for there to be an example or template
7566 file which the maintainer scripts use. Such files should
7567 be in <file>/usr/share/<var>package</var></file> or
7568 <file>/usr/lib/<var>package</var></file> (depending on whether
7569 they are architecture-independent or not). There should
7570 be symbolic links to them from
7571 <file>/usr/share/doc/<var>package</var>/examples</file> if
7572 they are examples, and should be perfectly ordinary
7573 <prgn>dpkg</prgn>-handled files (<em>not</em>
7574 configuration files).
7578 These two styles of configuration file handling must
7579 not be mixed, for that way lies madness:
7580 <prgn>dpkg</prgn> will ask about overwriting the file
7581 every time the package is upgraded.
7586 <heading>Sharing configuration files</heading>
7589 Packages which specify the same file as a
7590 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7591 with each other. (This is an instance of the general rule
7592 about not sharing files. Note that neither alternatives
7593 nor diversions are likely to be appropriate in this case;
7594 in particular, <prgn>dpkg</prgn> does not handle diverted
7595 <tt>conffile</tt>s well.)
7599 The maintainer scripts must not alter a <tt>conffile</tt>
7600 of <em>any</em> package, including the one the scripts
7605 If two or more packages use the same configuration file
7606 and it is reasonable for both to be installed at the same
7607 time, one of these packages must be defined as
7608 <em>owner</em> of the configuration file, i.e., it will be
7609 the package which handles that file as a configuration
7610 file. Other packages that use the configuration file must
7611 depend on the owning package if they require the
7612 configuration file to operate. If the other package will
7613 use the configuration file if present, but is capable of
7614 operating without it, no dependency need be declared.
7618 If it is desirable for two or more related packages to
7619 share a configuration file <em>and</em> for all of the
7620 related packages to be able to modify that configuration
7621 file, then the following should be done:
7622 <enumlist compact="compact">
7624 One of the related packages (the "owning" package)
7625 will manage the configuration file with maintainer
7626 scripts as described in the previous section.
7629 The owning package should also provide a program
7630 that the other packages may use to modify the
7634 The related packages must use the provided program
7635 to make any desired modifications to the
7636 configuration file. They should either depend on
7637 the core package to guarantee that the configuration
7638 modifier program is available or accept gracefully
7639 that they cannot modify the configuration file if it
7640 is not. (This is in addition to the fact that the
7641 configuration file may not even be present in the
7648 Sometimes it's appropriate to create a new package which
7649 provides the basic infrastructure for the other packages
7650 and which manages the shared configuration files. (The
7651 <tt>sgml-base</tt> package is a good example.)
7656 <heading>User configuration files ("dotfiles")</heading>
7659 The files in <file>/etc/skel</file> will automatically be
7660 copied into new user accounts by <prgn>adduser</prgn>.
7661 No other program should reference the files in
7662 <file>/etc/skel</file>.
7666 Therefore, if a program needs a dotfile to exist in
7667 advance in <file>$HOME</file> to work sensibly, that dotfile
7668 should be installed in <file>/etc/skel</file> and treated as a
7673 However, programs that require dotfiles in order to
7674 operate sensibly are a bad thing, unless they do create
7675 the dotfiles themselves automatically.
7679 Furthermore, programs should be configured by the Debian
7680 default installation to behave as closely to the upstream
7681 default behavior as possible.
7685 Therefore, if a program in a Debian package needs to be
7686 configured in some way in order to operate sensibly, that
7687 should be done using a site-wide configuration file placed
7688 in <file>/etc</file>. Only if the program doesn't support a
7689 site-wide default configuration and the package maintainer
7690 doesn't have time to add it may a default per-user file be
7691 placed in <file>/etc/skel</file>.
7695 <file>/etc/skel</file> should be as empty as we can make it.
7696 This is particularly true because there is no easy (or
7697 necessarily desirable) mechanism for ensuring that the
7698 appropriate dotfiles are copied into the accounts of
7699 existing users when a package is installed.
7705 <heading>Log files</heading>
7707 Log files should usually be named
7708 <file>/var/log/<var>package</var>.log</file>. If you have many
7709 log files, or need a separate directory for permission
7710 reasons (<file>/var/log</file> is writable only by
7711 <file>root</file>), you should usually create a directory named
7712 <file>/var/log/<var>package</var></file> and place your log
7717 Log files must be rotated occasionally so that they don't
7718 grow indefinitely; the best way to do this is to drop a log
7719 rotation configuration file into the directory
7720 <file>/etc/logrotate.d</file> and use the facilities provided by
7721 logrotate.<footnote>
7723 The traditional approach to log files has been to set up
7724 <em>ad hoc</em> log rotation schemes using simple shell
7725 scripts and cron. While this approach is highly
7726 customizable, it requires quite a lot of sysadmin work.
7727 Even though the original Debian system helped a little
7728 by automatically installing a system which can be used
7729 as a template, this was deemed not enough.
7733 The use of <prgn>logrotate</prgn>, a program developed
7734 by Red Hat, is better, as it centralizes log management.
7735 It has both a configuration file
7736 (<file>/etc/logrotate.conf</file>) and a directory where
7737 packages can drop their individual log rotation
7738 configurations (<file>/etc/logrotate.d</file>).
7741 Here is a good example for a logrotate config
7742 file (for more information see <manref name="logrotate"
7744 <example compact="compact">
7745 /var/log/foo/*.log {
7750 /etc/init.d/foo force-reload
7754 This rotates all files under <file>/var/log/foo</file>, saves 12
7755 compressed generations, and forces the daemon to reload its
7756 configuration information after the log rotation.
7760 Log files should be removed when the package is
7761 purged (but not when it is only removed). This should be
7762 done by the <prgn>postrm</prgn> script when it is called
7763 with the argument <tt>purge</tt> (see <ref
7764 id="removedetails">).
7769 <heading>Permissions and owners</heading>
7772 The rules in this section are guidelines for general use.
7773 If necessary you may deviate from the details below.
7774 However, if you do so you must make sure that what is done
7775 is secure and you should try to be as consistent as possible
7776 with the rest of the system. You should probably also
7777 discuss it on <prgn>debian-devel</prgn> first.
7781 Files should be owned by <tt>root:root</tt>, and made
7782 writable only by the owner and universally readable (and
7783 executable, if appropriate), that is mode 644 or 755.
7787 Directories should be mode 755 or (for group-writability)
7788 mode 2775. The ownership of the directory should be
7789 consistent with its mode: if a directory is mode 2775, it
7790 should be owned by the group that needs write access to
7793 When a package is upgraded, and the owner or permissions
7794 of a file included in the package has changed, dpkg
7795 arranges for the ownership and permissions to be
7796 correctly set upon installation. However, this does not
7797 extend to directories; the permissions and ownership of
7798 directories already on the system does not change on
7799 install or upgrade of packages. This makes sense, since
7800 otherwise common directories like <tt>/usr</tt> would
7801 always be in flux. To correctly change permissions of a
7802 directory the package owns, explicit action is required,
7803 usually in the <tt>postinst</tt> script. Care must be
7804 taken to handle downgrades as well, in that case.
7811 Setuid and setgid executables should be mode 4755 or 2755
7812 respectively, and owned by the appropriate user or group.
7813 They should not be made unreadable (modes like 4711 or
7814 2711 or even 4111); doing so achieves no extra security,
7815 because anyone can find the binary in the freely available
7816 Debian package; it is merely inconvenient. For the same
7817 reason you should not restrict read or execute permissions
7818 on non-set-id executables.
7822 Some setuid programs need to be restricted to particular
7823 sets of users, using file permissions. In this case they
7824 should be owned by the uid to which they are set-id, and by
7825 the group which should be allowed to execute them. They
7826 should have mode 4754; again there is no point in making
7827 them unreadable to those users who must not be allowed to
7832 It is possible to arrange that the system administrator can
7833 reconfigure the package to correspond to their local
7834 security policy by changing the permissions on a binary:
7835 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7836 described below.<footnote>
7837 Ordinary files installed by <prgn>dpkg</prgn> (as
7838 opposed to <tt>conffile</tt>s and other similar objects)
7839 normally have their permissions reset to the distributed
7840 permissions when the package is reinstalled. However,
7841 the use of <prgn>dpkg-statoverride</prgn> overrides this
7844 Another method you should consider is to create a group for
7845 people allowed to use the program(s) and make any setuid
7846 executables executable only by that group.
7850 If you need to create a new user or group for your package
7851 there are two possibilities. Firstly, you may need to
7852 make some files in the binary package be owned by this
7853 user or group, or you may need to compile the user or
7854 group id (rather than just the name) into the binary
7855 (though this latter should be avoided if possible, as in
7856 this case you need a statically allocated id).</p>
7859 If you need a statically allocated id, you must ask for a
7860 user or group id from the <tt>base-passwd</tt> maintainer,
7861 and must not release the package until you have been
7862 allocated one. Once you have been allocated one you must
7863 either make the package depend on a version of the
7864 <tt>base-passwd</tt> package with the id present in
7865 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7866 your package to create the user or group itself with the
7867 correct id (using <tt>adduser</tt>) in its
7868 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7869 the <prgn>postinst</prgn> is to be preferred if it is
7870 possible, otherwise a pre-dependency will be needed on the
7871 <tt>adduser</tt> package.)
7875 On the other hand, the program might be able to determine
7876 the uid or gid from the user or group name at runtime, so
7877 that a dynamically allocated id can be used. In this case
7878 you should choose an appropriate user or group name,
7879 discussing this on <prgn>debian-devel</prgn> and checking
7880 with the <package/base-passwd/ maintainer that it is unique and that
7881 they do not wish you to use a statically allocated id
7882 instead. When this has been checked you must arrange for
7883 your package to create the user or group if necessary using
7884 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7885 <prgn>postinst</prgn> script (again, the latter is to be
7886 preferred if it is possible).
7890 Note that changing the numeric value of an id associated
7891 with a name is very difficult, and involves searching the
7892 file system for all appropriate files. You need to think
7893 carefully whether a static or dynamic id is required, since
7894 changing your mind later will cause problems.
7897 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7899 This section is not intended as policy, but as a
7900 description of the use of <prgn>dpkg-statoverride</prgn>.
7904 If a system administrator wishes to have a file (or
7905 directory or other such thing) installed with owner and
7906 permissions different from those in the distributed Debian
7907 package, they can use the <prgn>dpkg-statoverride</prgn>
7908 program to instruct <prgn>dpkg</prgn> to use the different
7909 settings every time the file is installed. Thus the
7910 package maintainer should distribute the files with their
7911 normal permissions, and leave it for the system
7912 administrator to make any desired changes. For example, a
7913 daemon which is normally required to be setuid root, but
7914 in certain situations could be used without being setuid,
7915 should be installed setuid in the <tt>.deb</tt>. Then the
7916 local system administrator can change this if they wish.
7917 If there are two standard ways of doing it, the package
7918 maintainer can use <tt>debconf</tt> to find out the
7919 preference, and call <prgn>dpkg-statoverride</prgn> in the
7920 maintainer script if necessary to accommodate the system
7921 administrator's choice. Care must be taken during
7922 upgrades to not override an existing setting.
7926 Given the above, <prgn>dpkg-statoverride</prgn> is
7927 essentially a tool for system administrators and would not
7928 normally be needed in the maintainer scripts. There is
7929 one type of situation, though, where calls to
7930 <prgn>dpkg-statoverride</prgn> would be needed in the
7931 maintainer scripts, and that involves packages which use
7932 dynamically allocated user or group ids. In such a
7933 situation, something like the following idiom can be very
7934 helpful in the package's <prgn>postinst</prgn>, where
7935 <tt>sysuser</tt> is a dynamically allocated id:
7937 for i in /usr/bin/foo /usr/sbin/bar
7939 # only do something when no setting exists
7940 if ! dpkg-statoverride --list $i >/dev/null 2>&1
7942 #include: debconf processing, question about foo and bar
7943 if [ "$RET" = "true" ] ; then
7944 dpkg-statoverride --update --add sysuser root 4755 $i
7949 The corresponding code to remove the override when the package
7952 for i in /usr/bin/foo /usr/sbin/bar
7954 if dpkg-statoverride --list $i >/dev/null 2>&1
7956 dpkg-statoverride --remove $i
7966 <chapt id="customized-programs">
7967 <heading>Customized programs</heading>
7969 <sect id="arch-spec">
7970 <heading>Architecture specification strings</heading>
7973 If a program needs to specify an <em>architecture specification
7974 string</em> in some place, it should select one of the strings
7975 provided by <tt>dpkg-architecture -L</tt>. The strings are in
7976 the format <tt><var>os</var>-<var>arch</var></tt>, though the OS
7977 part is sometimes elided, as when the OS is Linux.
7981 Note that we don't want to use
7982 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7983 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7984 since this would make our programs incompatible with other
7985 Linux distributions. We also don't use something like
7986 <tt><var>arch</var>-unknown-linux</tt>, since the
7987 <tt>unknown</tt> does not look very good.
7990 <sect1 id="arch-wildcard-spec">
7991 <heading>Architecture wildcards</heading>
7994 A package may specify an architecture wildcard. Architecture
7995 wildcards are in the format <tt>any</tt> (which matches every
7996 architecture), <tt><var>os</var></tt>-any, or
7997 any-<tt><var>cpu</var></tt>. <footnote>
7998 Internally, the package system normalizes the GNU triplets
7999 and the Debian arches into Debian arch triplets (which are
8000 kind of inverted GNU triplets), with the first component of
8001 the triplet representing the libc and ABI in use, and then
8002 does matching against those triplets. However, such
8003 triplets are an internal implementation detail that should
8004 not be used by packages directly. The libc and ABI portion
8005 is handled internally by the package system based on
8006 the <var>os</var> and <var>cpu</var>.
8013 <heading>Daemons</heading>
8016 The configuration files <file>/etc/services</file>,
8017 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
8018 by the <prgn>netbase</prgn> package and must not be modified
8023 If a package requires a new entry in one of these files, the
8024 maintainer should get in contact with the
8025 <prgn>netbase</prgn> maintainer, who will add the entries
8026 and release a new version of the <prgn>netbase</prgn>
8031 The configuration file <file>/etc/inetd.conf</file> must not be
8032 modified by the package's scripts except via the
8033 <prgn>update-inetd</prgn> script or the
8034 <file>DebianNet.pm</file> Perl module. See their documentation
8035 for details on how to add entries.
8039 If a package wants to install an example entry into
8040 <file>/etc/inetd.conf</file>, the entry must be preceded with
8041 exactly one hash character (<tt>#</tt>). Such lines are
8042 treated as "commented out by user" by the
8043 <prgn>update-inetd</prgn> script and are not changed or
8044 activated during package updates.
8049 <heading>Using pseudo-ttys and modifying wtmp, utmp and
8053 Some programs need to create pseudo-ttys. This should be done
8054 using Unix98 ptys if the C library supports it. The resulting
8055 program must not be installed setuid root, unless that
8056 is required for other functionality.
8060 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
8061 <file>/var/log/lastlog</file> must be installed writable by
8062 group <tt>utmp</tt>. Programs which need to modify those
8063 files must be installed setgid <tt>utmp</tt>.
8068 <heading>Editors and pagers</heading>
8071 Some programs have the ability to launch an editor or pager
8072 program to edit or display a text document. Since there are
8073 lots of different editors and pagers available in the Debian
8074 distribution, the system administrator and each user should
8075 have the possibility to choose their preferred editor and
8080 In addition, every program should choose a good default
8081 editor/pager if none is selected by the user or system
8086 Thus, every program that launches an editor or pager must
8087 use the EDITOR or PAGER environment variable to determine
8088 the editor or pager the user wishes to use. If these
8089 variables are not set, the programs <file>/usr/bin/editor</file>
8090 and <file>/usr/bin/pager</file> should be used, respectively.
8094 These two files are managed through the <prgn>dpkg</prgn>
8095 "alternatives" mechanism. Thus every package providing an
8096 editor or pager must call the
8097 <prgn>update-alternatives</prgn> script to register these
8102 If it is very hard to adapt a program to make use of the
8103 EDITOR or PAGER variables, that program may be configured to
8104 use <file>/usr/bin/sensible-editor</file> and
8105 <file>/usr/bin/sensible-pager</file> as the editor or pager
8106 program respectively. These are two scripts provided in the
8107 <package>sensible-utils</package> package that check the EDITOR
8108 and PAGER variables and launch the appropriate program, and fall
8109 back to <file>/usr/bin/editor</file>
8110 and <file>/usr/bin/pager</file> if the variable is not set.
8114 A program may also use the VISUAL environment variable to
8115 determine the user's choice of editor. If it exists, it
8116 should take precedence over EDITOR. This is in fact what
8117 <file>/usr/bin/sensible-editor</file> does.
8121 It is not required for a package to depend on
8122 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
8123 package to provide such virtual packages.<footnote>
8124 The Debian base system already provides an editor and a
8130 <sect id="web-appl">
8131 <heading>Web servers and applications</heading>
8134 This section describes the locations and URLs that should
8135 be used by all web servers and web applications in the
8142 Cgi-bin executable files are installed in the
8144 <example compact="compact">
8145 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
8147 and should be referred to as
8148 <example compact="compact">
8149 http://localhost/cgi-bin/<var>cgi-bin-name</var>
8155 <p>Access to HTML documents</p>
8158 HTML documents for a package are stored in
8159 <file>/usr/share/doc/<var>package</var></file>
8160 and can be referred to as
8161 <example compact="compact">
8162 http://localhost/doc/<var>package</var>/<var>filename</var>
8167 The web server should restrict access to the document
8168 tree so that only clients on the same host can read
8169 the documents. If the web server does not support such
8170 access controls, then it should not provide access at
8171 all, or ask about providing access during installation.
8176 <p>Access to images</p>
8178 It is recommended that images for a package be stored
8179 in <tt>/usr/share/images/<var>package</var></tt> and
8180 may be referred to through an alias <tt>/images/</tt>
8183 http://localhost/images/<package>/<filename>
8190 <p>Web Document Root</p>
8193 Web Applications should try to avoid storing files in
8194 the Web Document Root. Instead they should use the
8195 /usr/share/doc/<var>package</var> directory for
8196 documents and register the Web Application via the
8197 <package>doc-base</package> package. If access to the
8198 web document root is unavoidable then use
8199 <example compact="compact">
8202 as the Document Root. This might be just a symbolic
8203 link to the location where the system administrator
8204 has put the real document root.
8207 <item><p>Providing httpd and/or httpd-cgi</p>
8209 All web servers should provide the virtual package
8210 <tt>httpd</tt>. If a web server has CGI support it should
8211 provide <tt>httpd-cgi</tt> additionally.
8214 All web applications which do not contain CGI scripts should
8215 depend on <tt>httpd</tt>, all those web applications which
8216 <tt>do</tt> contain CGI scripts, should depend on
8224 <sect id="mail-transport-agents">
8225 <heading>Mail transport, delivery and user agents</heading>
8228 Debian packages which process electronic mail, whether mail
8229 user agents (MUAs) or mail transport agents (MTAs), must
8230 ensure that they are compatible with the configuration
8231 decisions below. Failure to do this may result in lost
8232 mail, broken <tt>From:</tt> lines, and other serious brain
8237 The mail spool is <file>/var/mail</file> and the interface to
8238 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8239 the FHS). On older systems, the mail spool may be
8240 physically located in <file>/var/spool/mail</file>, but all
8241 access to the mail spool should be via the
8242 <file>/var/mail</file> symlink. The mail spool is part of the
8243 base system and not part of the MTA package.
8247 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8248 programs (such as IMAP daemons) must lock the mailbox in an
8249 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8250 be combined with dot locking. To avoid deadlocks, a program
8251 should use <tt>fcntl()</tt> first and dot locking after
8252 this, or alternatively implement the two locking methods in
8253 a non blocking way<footnote>
8254 If it is not possible to establish both locks, the
8255 system shouldn't wait for the second lock to be
8256 established, but remove the first lock, wait a (random)
8257 time, and start over locking again.
8258 </footnote>. Using the functions <tt>maillock</tt> and
8259 <tt>mailunlock</tt> provided by the
8260 <tt>liblockfile*</tt><footnote>
8261 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8262 to use these functions.
8263 </footnote> packages is the recommended way to realize this.
8267 Mailboxes are generally either mode 600 and owned by
8268 <var>user</var> or mode 660 and owned by
8269 <tt><var>user</var>:mail</tt><footnote>
8270 There are two traditional permission schemes for mail spools:
8271 mode 600 with all mail delivery done by processes running as
8272 the destination user, or mode 660 and owned by group mail with
8273 mail delivery done by a process running as a system user in
8274 group mail. Historically, Debian required mode 660 mail
8275 spools to enable the latter model, but that model has become
8276 increasingly uncommon and the principle of least privilege
8277 indicates that mail systems that use the first model should
8278 use permissions of 600. If delivery to programs is permitted,
8279 it's easier to keep the mail system secure if the delivery
8280 agent runs as the destination user. Debian Policy therefore
8281 permits either scheme.
8282 </footnote>. The local system administrator may choose a
8283 different permission scheme; packages should not make
8284 assumptions about the permission and ownership of mailboxes
8285 unless required (such as when creating a new mailbox). A MUA
8286 may remove a mailbox (unless it has nonstandard permissions) in
8287 which case the MTA or another MUA must recreate it if needed.
8291 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8292 be setgid mail to do the locking mentioned above (and
8293 must obviously avoid accessing other users' mailboxes
8294 using this privilege).</p>
8297 <file>/etc/aliases</file> is the source file for the system mail
8298 aliases (e.g., postmaster, usenet, etc.), it is the one
8299 which the sysadmin and <prgn>postinst</prgn> scripts may
8300 edit. After <file>/etc/aliases</file> is edited the program or
8301 human editing it must call <prgn>newaliases</prgn>. All MTA
8302 packages must come with a <prgn>newaliases</prgn> program,
8303 even if it does nothing, but older MTA packages did not do
8304 this so programs should not fail if <prgn>newaliases</prgn>
8305 cannot be found. Note that because of this, all MTA
8306 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8307 <tt>Replaces: mail-transport-agent</tt> control file
8312 The convention of writing <tt>forward to
8313 <var>address</var></tt> in the mailbox itself is not
8314 supported. Use a <tt>.forward</tt> file instead.</p>
8317 The <prgn>rmail</prgn> program used by UUCP
8318 for incoming mail should be <file>/usr/sbin/rmail</file>.
8319 Likewise, <prgn>rsmtp</prgn>, for receiving
8320 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8324 If your package needs to know what hostname to use on (for
8325 example) outgoing news and mail messages which are generated
8326 locally, you should use the file <file>/etc/mailname</file>. It
8327 will contain the portion after the username and <tt>@</tt>
8328 (at) sign for email addresses of users on the machine
8329 (followed by a newline).
8333 Such a package should check for the existence of this file
8334 when it is being configured. If it exists, it should be
8335 used without comment, although an MTA's configuration script
8336 may wish to prompt the user even if it finds that this file
8337 exists. If the file does not exist, the package should
8338 prompt the user for the value (preferably using
8339 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8340 as well as using it in the package's configuration. The
8341 prompt should make it clear that the name will not just be
8342 used by that package. For example, in this situation the
8343 <tt>inn</tt> package could say something like:
8344 <example compact="compact">
8345 Please enter the "mail name" of your system. This is the
8346 hostname portion of the address to be shown on outgoing
8347 news and mail messages. The default is
8348 <var>syshostname</var>, your system's host name. Mail
8349 name ["<var>syshostname</var>"]:
8351 where <var>syshostname</var> is the output of <tt>hostname
8357 <heading>News system configuration</heading>
8360 All the configuration files related to the NNTP (news)
8361 servers and clients should be located under
8362 <file>/etc/news</file>.</p>
8365 There are some configuration issues that apply to a number
8366 of news clients and server packages on the machine. These
8370 <tag><file>/etc/news/organization</file></tag>
8372 A string which should appear as the
8373 organization header for all messages posted
8374 by NNTP clients on the machine
8377 <tag><file>/etc/news/server</file></tag>
8379 Contains the FQDN of the upstream NNTP
8380 server, or localhost if the local machine is
8385 Other global files may be added as required for cross-package news
8392 <heading>Programs for the X Window System</heading>
8395 <heading>Providing X support and package priorities</heading>
8398 Programs that can be configured with support for the X
8399 Window System must be configured to do so and must declare
8400 any package dependencies necessary to satisfy their
8401 runtime requirements when using the X Window System. If
8402 such a package is of higher priority than the X packages
8403 on which it depends, it is required that either the
8404 X-specific components be split into a separate package, or
8405 that an alternative version of the package, which includes
8406 X support, be provided, or that the package's priority be
8412 <heading>Packages providing an X server</heading>
8415 Packages that provide an X server that, directly or
8416 indirectly, communicates with real input and display
8417 hardware should declare in their control data that they
8418 provide the virtual package <tt>xserver</tt>.<footnote>
8419 This implements current practice, and provides an
8420 actual policy for usage of the <tt>xserver</tt>
8421 virtual package which appears in the virtual packages
8422 list. In a nutshell, X servers that interface
8423 directly with the display and input hardware or via
8424 another subsystem (e.g., GGI) should provide
8425 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8426 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8432 <heading>Packages providing a terminal emulator</heading>
8435 Packages that provide a terminal emulator for the X Window
8436 System which meet the criteria listed below should declare
8437 in their control data that they provide the virtual
8438 package <tt>x-terminal-emulator</tt>. They should also
8439 register themselves as an alternative for
8440 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8445 To be an <tt>x-terminal-emulator</tt>, a program must:
8446 <list compact="compact">
8448 Be able to emulate a DEC VT100 terminal, or a
8449 compatible terminal.
8453 Support the command-line option <tt>-e
8454 <var>command</var></tt>, which creates a new
8455 terminal window<footnote>
8456 "New terminal window" does not necessarily mean
8457 a new top-level X window directly parented by
8458 the window manager; it could, if the terminal
8459 emulator application were so coded, be a new
8460 "view" in a multiple-document interface (MDI).
8462 and runs the specified <var>command</var>,
8463 interpreting the entirety of the rest of the command
8464 line as a command to pass straight to exec, in the
8465 manner that <tt>xterm</tt> does.
8469 Support the command-line option <tt>-T
8470 <var>title</var></tt>, which creates a new terminal
8471 window with the window title <var>title</var>.
8478 <heading>Packages providing a window manager</heading>
8481 Packages that provide a window manager should declare in
8482 their control data that they provide the virtual package
8483 <tt>x-window-manager</tt>. They should also register
8484 themselves as an alternative for
8485 <file>/usr/bin/x-window-manager</file>, with a priority
8486 calculated as follows:
8487 <list compact="compact">
8489 Start with a priority of 20.
8493 If the window manager supports the Debian menu
8494 system, add 20 points if this support is available
8495 in the package's default configuration (i.e., no
8496 configuration files belonging to the system or user
8497 have to be edited to activate the feature); if
8498 configuration files must be modified, add only 10
8504 If the window manager complies with <url
8505 id="http://www.freedesktop.org/Standards/wm-spec"
8506 name="The Window Manager Specification Project">,
8507 written by the <url id="http://www.freedesktop.org/"
8508 name="Free Desktop Group">, add 40 points.
8512 If the window manager permits the X session to be
8513 restarted using a <em>different</em> window manager
8514 (without killing the X server) in its default
8515 configuration, add 10 points; otherwise add none.
8522 <heading>Packages providing fonts</heading>
8525 Packages that provide fonts for the X Window
8527 For the purposes of Debian Policy, a "font for the X
8528 Window System" is one which is accessed via X protocol
8529 requests. Fonts for the Linux console, for PostScript
8530 renderer, or any other purpose, do not fit this
8531 definition. Any tool which makes such fonts available
8532 to the X Window System, however, must abide by this
8535 must do a number of things to ensure that they are both
8536 available without modification of the X or font server
8537 configuration, and that they do not corrupt files used by
8538 other font packages to register information about
8542 Fonts of any type supported by the X Window System
8543 must be in a separate binary package from any
8544 executables, libraries, or documentation (except
8545 that specific to the fonts shipped, such as their
8546 license information). If one or more of the fonts
8547 so packaged are necessary for proper operation of
8548 the package with which they are associated the font
8549 package may be Recommended; if the fonts merely
8550 provide an enhancement, a Suggests relationship may
8551 be used. Packages must not Depend on font
8553 This is because the X server may retrieve fonts
8554 from the local file system or over the network
8555 from an X font server; the Debian package system
8556 is empowered to deal only with the local
8562 BDF fonts must be converted to PCF fonts with the
8563 <prgn>bdftopcf</prgn> utility (available in the
8564 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8565 placed in a directory that corresponds to their
8567 <list compact="compact">
8569 100 dpi fonts must be placed in
8570 <file>/usr/share/fonts/X11/100dpi/</file>.
8574 75 dpi fonts must be placed in
8575 <file>/usr/share/fonts/X11/75dpi/</file>.
8579 Character-cell fonts, cursor fonts, and other
8580 low-resolution fonts must be placed in
8581 <file>/usr/share/fonts/X11/misc/</file>.
8587 Type 1 fonts must be placed in
8588 <file>/usr/share/fonts/X11/Type1/</file>. If font
8589 metric files are available, they must be placed here
8594 Subdirectories of <file>/usr/share/fonts/X11/</file>
8595 other than those listed above must be neither
8596 created nor used. (The <file>PEX</file>, <file>CID</file>,
8597 <file>Speedo</file>, and <file>cyrillic</file> directories
8598 are excepted for historical reasons, but installation of
8599 files into these directories remains discouraged.)
8603 Font packages may, instead of placing files directly
8604 in the X font directories listed above, provide
8605 symbolic links in that font directory pointing to
8606 the files' actual location in the filesystem. Such
8607 a location must comply with the FHS.
8611 Font packages should not contain both 75dpi and
8612 100dpi versions of a font. If both are available,
8613 they should be provided in separate binary packages
8614 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8615 the names of the packages containing the
8616 corresponding fonts.
8620 Fonts destined for the <file>misc</file> subdirectory
8621 should not be included in the same package as 75dpi
8622 or 100dpi fonts; instead, they should be provided in
8623 a separate package with <tt>-misc</tt> appended to
8628 Font packages must not provide the files
8629 <file>fonts.dir</file>, <file>fonts.alias</file>, or
8630 <file>fonts.scale</file> in a font directory:
8633 <file>fonts.dir</file> files must not be provided at all.
8637 <file>fonts.alias</file> and <file>fonts.scale</file>
8638 files, if needed, should be provided in the
8640 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
8641 where <var>fontdir</var> is the name of the
8643 <file>/usr/share/fonts/X11/</file> where the
8644 package's corresponding fonts are stored
8645 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
8646 <var>package</var> is the name of the package
8647 that provides these fonts, and
8648 <var>extension</var> is either <tt>scale</tt>
8649 or <tt>alias</tt>, whichever corresponds to
8656 Font packages must declare a dependency on
8657 <tt>xfonts-utils</tt> in their control
8662 Font packages that provide one or more
8663 <file>fonts.scale</file> files as described above must
8664 invoke <prgn>update-fonts-scale</prgn> on each
8665 directory into which they installed fonts
8666 <em>before</em> invoking
8667 <prgn>update-fonts-dir</prgn> on that directory.
8668 This invocation must occur in both the
8669 <prgn>postinst</prgn> (for all arguments) and
8670 <prgn>postrm</prgn> (for all arguments except
8671 <tt>upgrade</tt>) scripts.
8675 Font packages that provide one or more
8676 <file>fonts.alias</file> files as described above must
8677 invoke <prgn>update-fonts-alias</prgn> on each
8678 directory into which they installed fonts. This
8679 invocation must occur in both the
8680 <prgn>postinst</prgn> (for all arguments) and
8681 <prgn>postrm</prgn> (for all arguments except
8682 <tt>upgrade</tt>) scripts.
8686 Font packages must invoke
8687 <prgn>update-fonts-dir</prgn> on each directory into
8688 which they installed fonts. This invocation must
8689 occur in both the <prgn>postinst</prgn> (for all
8690 arguments) and <prgn>postrm</prgn> (for all
8691 arguments except <tt>upgrade</tt>) scripts.
8695 Font packages must not provide alias names for the
8696 fonts they include which collide with alias names
8697 already in use by fonts already packaged.
8701 Font packages must not provide fonts with the same
8702 XLFD registry name as another font already packaged.
8708 <sect1 id="appdefaults">
8709 <heading>Application defaults files</heading>
8712 Application defaults files must be installed in the
8713 directory <file>/etc/X11/app-defaults/</file> (use of a
8714 localized subdirectory of <file>/etc/X11/</file> as described
8715 in the <em>X Toolkit Intrinsics - C Language
8716 Interface</em> manual is also permitted). They must be
8717 registered as <tt>conffile</tt>s or handled as
8718 configuration files.
8722 Customization of programs' X resources may also be
8723 supported with the provision of a file with the same name
8724 as that of the package placed in
8725 the <file>/etc/X11/Xresources/</file> directory, which
8726 must be registered as a <tt>conffile</tt> or handled as a
8727 configuration file.<footnote>
8728 Note that this mechanism is not the same as using
8729 app-defaults; app-defaults are tied to the client
8730 binary on the local file system, whereas X resources
8731 are stored in the X server and affect all connecting
8738 <heading>Installation directory issues</heading>
8741 Historically, packages using the X Window System used a
8742 separate set of installation directories from other packages.
8743 This practice has been discontinued and packages using the X
8744 Window System should now generally be installed in the same
8745 directories as any other package. Specifically, packages must
8746 not install files under the <file>/usr/X11R6/</file> directory
8747 and the <file>/usr/X11R6/</file> directory hierarchy should be
8748 regarded as obsolete.
8752 Include files previously installed under
8753 <file>/usr/X11R6/include/X11/</file> should be installed into
8754 <file>/usr/include/X11/</file>. For files previously
8755 installed into subdirectories of
8756 <file>/usr/X11R6/lib/X11/</file>, package maintainers should
8757 determine if subdirectories of <file>/usr/lib/</file> and
8758 <file>/usr/share/</file> can be used. If not, a subdirectory
8759 of <file>/usr/lib/X11/</file> should be used.
8763 Configuration files for window, display, or session managers
8764 or other applications that are tightly integrated with the X
8765 Window System may be placed in a subdirectory
8766 of <file>/etc/X11/</file> corresponding to the package name.
8767 Other X Window System applications should use
8768 the <file>/etc/</file> directory unless otherwise mandated by
8769 policy (such as for <ref id="appdefaults">).
8774 <heading>The OSF/Motif and OpenMotif libraries</heading>
8777 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8778 OpenMotif libraries</em><footnote>
8779 OSF/Motif and OpenMotif are collectively referred to as
8780 "Motif" in this policy document.
8782 should be compiled against and tested with LessTif (a free
8783 re-implementation of Motif) instead. If the maintainer
8784 judges that the program or programs do not work
8785 sufficiently well with LessTif to be distributed and
8786 supported, but do so when compiled against Motif, then two
8787 versions of the package should be created; one linked
8788 statically against Motif and with <tt>-smotif</tt>
8789 appended to the package name, and one linked dynamically
8790 against Motif and with <tt>-dmotif</tt> appended to the
8795 Both Motif-linked versions are dependent
8796 upon non-DFSG-compliant software and thus cannot be
8797 uploaded to the <em>main</em> distribution; if the
8798 software is itself DFSG-compliant it may be uploaded to
8799 the <em>contrib</em> distribution. While known existing
8800 versions of Motif permit unlimited redistribution of
8801 binaries linked against the library (whether statically or
8802 dynamically), it is the package maintainer's
8803 responsibility to determine whether this is permitted by
8804 the license of the copy of Motif in their possession.
8810 <heading>Perl programs and modules</heading>
8813 Perl programs and modules should follow the current Perl policy.
8817 The Perl policy can be found in the <tt>perl-policy</tt>
8818 files in the <tt>debian-policy</tt> package.
8819 It is also available from the Debian web mirrors at
8820 <tt><url name="/doc/packaging-manuals/perl-policy/"
8821 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8826 <heading>Emacs lisp programs</heading>
8829 Please refer to the "Debian Emacs Policy" for details of how to
8830 package emacs lisp programs.
8834 The Emacs policy is available in
8835 <file>debian-emacs-policy.gz</file> of the
8836 <package>emacsen-common</package> package.
8837 It is also available from the Debian web mirrors at
8838 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8839 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8844 <heading>Games</heading>
8847 The permissions on <file>/var/games</file> are mode 755, owner
8848 <tt>root</tt> and group <tt>root</tt>.
8852 Each game decides on its own security policy.</p>
8855 Games which require protected, privileged access to
8856 high-score files, saved games, etc., may be made
8857 set-<em>group</em>-id (mode 2755) and owned by
8858 <tt>root:games</tt>, and use files and directories with
8859 appropriate permissions (770 <tt>root:games</tt>, for
8860 example). They must not be made
8861 set-<em>user</em>-id, as this causes security problems. (If
8862 an attacker can subvert any set-user-id game they can
8863 overwrite the executable of any other, causing other players
8864 of these games to run a Trojan horse program. With a
8865 set-group-id game the attacker only gets access to less
8866 important game data, and if they can get at the other
8867 players' accounts at all it will take considerably more
8871 Some packages, for example some fortune cookie programs, are
8872 configured by the upstream authors to install with their
8873 data files or other static information made unreadable so
8874 that they can only be accessed through set-id programs
8875 provided. You should not do this in a Debian package: anyone can
8876 download the <file>.deb</file> file and read the data from it,
8877 so there is no point making the files unreadable. Not
8878 making the files unreadable also means that you don't have
8879 to make so many programs set-id, which reduces the risk of a
8883 As described in the FHS, binaries of games should be
8884 installed in the directory <file>/usr/games</file>. This also
8885 applies to games that use the X Window System. Manual pages
8886 for games (X and non-X games) should be installed in
8887 <file>/usr/share/man/man6</file>.</p>
8893 <heading>Documentation</heading>
8896 <heading>Manual pages</heading>
8899 You should install manual pages in <prgn>nroff</prgn> source
8900 form, in appropriate places under <file>/usr/share/man</file>.
8901 You should only use sections 1 to 9 (see the FHS for more
8902 details). You must not install a pre-formatted "cat page".
8906 Each program, utility, and function should have an
8907 associated manual page included in the same package. It is
8908 suggested that all configuration files also have a manual
8909 page included as well. Manual pages for protocols and other
8910 auxiliary things are optional.
8914 If no manual page is available, this is considered as a bug
8915 and should be reported to the Debian Bug Tracking System (the
8916 maintainer of the package is allowed to write this bug report
8917 themselves, if they so desire). Do not close the bug report
8918 until a proper man page is available.<footnote>
8919 It is not very hard to write a man page. See the
8920 <url id="http://www.schweikhardt.net/man_page_howto.html"
8921 name="Man-Page-HOWTO">,
8922 <manref name="man" section="7">, the examples
8923 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8924 the helper programs <prgn>help2man</prgn>, or the
8925 directory <file>/usr/share/doc/man-db/examples</file>.
8930 You may forward a complaint about a missing man page to the
8931 upstream authors, and mark the bug as forwarded in the
8932 Debian bug tracking system. Even though the GNU Project do
8933 not in general consider the lack of a man page to be a bug,
8934 we do; if they tell you that they don't consider it a bug
8935 you should leave the bug in our bug tracking system open
8940 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8944 If one man page needs to be accessible via several names it
8945 is better to use a symbolic link than the <file>.so</file>
8946 feature, but there is no need to fiddle with the relevant
8947 parts of the upstream source to change from <file>.so</file> to
8948 symlinks: don't do it unless it's easy. You should not
8949 create hard links in the manual page directories, nor put
8950 absolute filenames in <file>.so</file> directives. The filename
8951 in a <file>.so</file> in a man page should be relative to the
8952 base of the man page tree (usually
8953 <file>/usr/share/man</file>). If you do not create any links
8954 (whether symlinks, hard links, or <tt>.so</tt> directives)
8955 in the file system to the alternate names of the man page,
8956 then you should not rely on <prgn>man</prgn> finding your
8957 man page under those names based solely on the information in
8958 the man page's header.<footnote>
8959 Supporting this in <prgn>man</prgn> often requires
8960 unreasonable processing time to find a manual page or to
8961 report that none exists, and moves knowledge into man's
8962 database that would be better left in the file system.
8963 This support is therefore deprecated and will cease to
8964 be present in the future.
8969 Manual pages in locale-specific subdirectories of
8970 <file>/usr/share/man</file> should use either UTF-8 or the usual
8971 legacy encoding for that language (normally the one corresponding
8972 to the shortest relevant locale name in
8973 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
8974 <file>/usr/share/man/fr</file> should use either UTF-8 or
8975 ISO-8859-1.<footnote>
8976 <prgn>man</prgn> will automatically detect whether UTF-8 is in
8977 use. In future, all manual pages will be required to use
8983 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
8984 included in the subdirectory name unless it indicates a
8985 significant difference in the language, as this excludes
8986 speakers of the language in other countries.<footnote>
8987 At the time of writing, Chinese and Portuguese are the main
8988 languages with such differences, so <file>pt_BR</file>,
8989 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
8994 If a localized version of a manual page is provided, it should
8995 either be up-to-date or it should be obvious to the reader that
8996 it is outdated and the original manual page should be used
8997 instead. This can be done either by a note at the beginning of
8998 the manual page or by showing the missing or changed portions in
8999 the original language instead of the target language.
9004 <heading>Info documents</heading>
9007 Info documents should be installed in <file>/usr/share/info</file>.
9008 They should be compressed with <tt>gzip -9</tt>.
9012 The <prgn>install-info</prgn> program maintains a directory of
9013 installed info documents in <file>/usr/share/info/dir</file> for
9014 the use of info readers.<footnote>
9015 It was previously necessary for packages installing info
9016 documents to run <prgn>install-info</prgn> from maintainer
9017 scripts. This is no longer necessary. The installation
9018 system now uses dpkg triggers.
9020 This file must not be included in packages. Packages containing
9021 info documents should depend on <tt>dpkg (>= 1.15.4) |
9022 install-info</tt> to ensure that the directory file is properly
9023 rebuilt during partial upgrades from Debian 5.0 (lenny) and
9028 Info documents should contain section and directory entry
9029 information in the document for the use
9030 of <prgn>install-info</prgn>. The section should be specified
9031 via a line starting with <tt>INFO-DIR-SECTION</tt> followed by a
9032 space and the section of this info page. The directory entry or
9033 entries should be included between
9034 a <tt>START-INFO-DIR-ENTRY</tt> line and
9035 an <tt>END-INFO-DIR-ENTRY</tt> line. For example:
9037 INFO-DIR-SECTION Individual utilities
9038 START-INFO-DIR-ENTRY
9039 * example: (example). An example info directory entry.
9042 To determine which section to use, you should look
9043 at <file>/usr/share/info/dir</file> on your system and choose
9044 the most relevant (or create a new section if none of the
9045 current sections are relevant).<footnote>
9046 Normally, info documents are generated from Texinfo source.
9047 To include this information in the generated info document, if
9048 it is absent, add commands like:
9050 @dircategory Individual utilities
9052 * example: (example). An example info directory entry.
9055 to the Texinfo source of the document and ensure that the info
9056 documents are rebuilt from source during the package build.
9062 <heading>Additional documentation</heading>
9065 Any additional documentation that comes with the package may
9066 be installed at the discretion of the package maintainer.
9067 Plain text documentation should be installed in the directory
9068 <file>/usr/share/doc/<var>package</var></file>, where
9069 <var>package</var> is the name of the package, and
9070 compressed with <tt>gzip -9</tt> unless it is small.
9074 If a package comes with large amounts of documentation which
9075 many users of the package will not require you should create
9076 a separate binary package to contain it, so that it does not
9077 take up disk space on the machines of users who do not need
9078 or want it installed.</p>
9081 It is often a good idea to put text information files
9082 (<file>README</file>s, changelogs, and so forth) that come with
9083 the source package in <file>/usr/share/doc/<var>package</var></file>
9084 in the binary package. However, you don't need to install
9085 the instructions for building and installing the package, of
9089 Packages must not require the existence of any files in
9090 <file>/usr/share/doc/</file> in order to function
9092 The system administrator should be able to
9093 delete files in <file>/usr/share/doc/</file> without causing
9094 any programs to break.
9096 Any files that are referenced by programs but are also
9097 useful as stand alone documentation should be installed under
9098 <file>/usr/share/<var>package</var>/</file> with symbolic links from
9099 <file>/usr/share/doc/<var>package</var></file>.
9103 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9104 link to another directory in <file>/usr/share/doc</file> only if
9105 the two packages both come from the same source and the
9106 first package Depends on the second.<footnote>
9108 Please note that this does not override the section on
9109 changelog files below, so the file
9110 <file>/usr/share/doc/<var>package</var>/changelog.Debian.gz</file>
9111 must refer to the changelog for the current version of
9112 <var>package</var> in question. In practice, this means
9113 that the sources of the target and the destination of the
9114 symlink must be the same (same source package and
9121 Former Debian releases placed all additional documentation
9122 in <file>/usr/doc/<var>package</var></file>. This has been
9123 changed to <file>/usr/share/doc/<var>package</var></file>,
9124 and packages must not put documentation in the directory
9125 <file>/usr/doc/<var>package</var></file>. <footnote>
9126 At this phase of the transition, we no longer require a
9127 symbolic link in <file>/usr/doc/</file>. At a later point,
9128 policy shall change to make the symbolic links a bug.
9134 <heading>Preferred documentation formats</heading>
9137 The unification of Debian documentation is being carried out
9141 If your package comes with extensive documentation in a
9142 markup format that can be converted to various other formats
9143 you should if possible ship HTML versions in a binary
9144 package, in the directory
9145 <file>/usr/share/doc/<var>appropriate-package</var></file> or
9146 its subdirectories.<footnote>
9147 The rationale: The important thing here is that HTML
9148 docs should be available in <em>some</em> package, not
9149 necessarily in the main binary package.
9154 Other formats such as PostScript may be provided at the
9155 package maintainer's discretion.
9159 <sect id="copyrightfile">
9160 <heading>Copyright information</heading>
9163 Every package must be accompanied by a verbatim copy of its
9164 copyright information and distribution license in the file
9165 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
9166 file must neither be compressed nor be a symbolic link.
9170 In addition, the copyright file must say where the upstream
9171 sources (if any) were obtained. It should name the original
9172 authors of the package and the Debian maintainer(s) who were
9173 involved with its creation.
9177 Packages in the <em>contrib</em> or <em>non-free</em> archive
9178 areas should state in the copyright file that the package is not
9179 part of the Debian GNU/Linux distribution and briefly explain
9184 A copy of the file which will be installed in
9185 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9186 be in <file>debian/copyright</file> in the source package.
9190 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9191 link to another directory in <file>/usr/share/doc</file> only if
9192 the two packages both come from the same source and the
9193 first package Depends on the second. These rules are
9194 important because copyrights must be extractable by
9199 Packages distributed under the UCB BSD license, the Apache
9200 license (version 2.0), the Artistic license, the GNU GPL
9201 (version 2 or 3), the GNU LGPL (versions 2, 2.1, or 3), and the
9202 GNU FDL (versions 1.2 or 1.3) should refer to the corresponding
9203 files under <file>/usr/share/common-licenses</file>,<footnote>
9206 <file>/usr/share/common-licenses/BSD</file>,
9207 <file>/usr/share/common-licenses/Apache-2.0</file>,
9208 <file>/usr/share/common-licenses/Artistic</file>,
9209 <file>/usr/share/common-licenses/GPL-2</file>,
9210 <file>/usr/share/common-licenses/GPL-3</file>,
9211 <file>/usr/share/common-licenses/LGPL-2</file>,
9212 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9213 <file>/usr/share/common-licenses/LGPL-3</file>,
9214 <file>/usr/share/common-licenses/GFDL-1.2</file>, and
9215 <file>/usr/share/common-licenses/GFDL-1.3</file>
9218 </footnote> rather than quoting them in the copyright
9223 You should not use the copyright file as a general <file>README</file>
9224 file. If your package has such a file it should be
9225 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9226 <file>README.Debian</file> or some other appropriate place.</p>
9230 <heading>Examples</heading>
9233 Any examples (configurations, source files, whatever),
9234 should be installed in a directory
9235 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9236 files should not be referenced by any program: they're there
9237 for the benefit of the system administrator and users as
9238 documentation only. Architecture-specific example files
9239 should be installed in a directory
9240 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9242 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9243 latter directory itself may be a symbolic link to the
9248 If the purpose of a package is to provide examples, then the
9249 example files may be installed into
9250 <file>/usr/share/doc/<var>package</var></file>.
9254 <sect id="changelogs">
9255 <heading>Changelog files</heading>
9258 Packages that are not Debian-native must contain a
9259 compressed copy of the <file>debian/changelog</file> file from
9260 the Debian source tree in
9261 <file>/usr/share/doc/<var>package</var></file> with the name
9262 <file>changelog.Debian.gz</file>.
9266 If an upstream changelog is available, it should be accessible as
9267 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9268 plain text. If the upstream changelog is distributed in
9269 HTML, it should be made available in that form as
9270 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9271 and a plain text <file>changelog.gz</file> should be generated
9272 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9273 the upstream changelog files do not already conform to this
9274 naming convention, then this may be achieved either by
9275 renaming the files, or by adding a symbolic link, at the
9276 maintainer's discretion.<footnote>
9277 Rationale: People should not have to look in places for
9278 upstream changelogs merely because they are given
9279 different names or are distributed in HTML format.
9284 All of these files should be installed compressed using
9285 <tt>gzip -9</tt>, as they will become large with time even
9286 if they start out small.
9290 If the package has only one changelog which is used both as
9291 the Debian changelog and the upstream one because there is
9292 no separate upstream maintainer then that changelog should
9293 usually be installed as
9294 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9295 there is a separate upstream maintainer, but no upstream
9296 changelog, then the Debian changelog should still be called
9297 <file>changelog.Debian.gz</file>.
9301 For details about the format and contents of the Debian
9302 changelog file, please see <ref id="dpkgchangelog">.
9307 <appendix id="pkg-scope">
9308 <heading>Introduction and scope of these appendices</heading>
9311 These appendices are taken essentially verbatim from the
9312 now-deprecated Packaging Manual, version 3.2.1.0. They are
9313 the chapters which are likely to be of use to package
9314 maintainers and which have not already been included in the
9315 policy document itself. Most of these sections are very likely
9316 not relevant to policy; they should be treated as
9317 documentation for the packaging system. Please note that these
9318 appendices are included for convenience, and for historical
9319 reasons: they used to be part of policy package, and they have
9320 not yet been incorporated into dpkg documentation. However,
9321 they still have value, and hence they are presented here.
9325 They have not yet been checked to ensure that they are
9326 compatible with the contents of policy, and if there are any
9327 contradictions, the version in the main policy document takes
9328 precedence. The remaining chapters of the old Packaging
9329 Manual have also not been read in detail to ensure that there
9330 are not parts which have been left out. Both of these will be
9335 Certain parts of the Packaging manual were integrated into the
9336 Policy Manual proper, and removed from the appendices. Links
9337 have been placed from the old locations to the new ones.
9341 <prgn>dpkg</prgn> is a suite of programs for creating binary
9342 package files and installing and removing them on Unix
9344 <prgn>dpkg</prgn> is targeted primarily at Debian
9345 GNU/Linux, but may work on or be ported to other
9351 The binary packages are designed for the management of
9352 installed executable programs (usually compiled binaries) and
9353 their associated data, though source code examples and
9354 documentation are provided as part of some packages.</p>
9357 This manual describes the technical aspects of creating Debian
9358 binary packages (<file>.deb</file> files). It documents the
9359 behavior of the package management programs
9360 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9361 they interact with packages.</p>
9364 It also documents the interaction between
9365 <prgn>dselect</prgn>'s core and the access method scripts it
9366 uses to actually install the selected packages, and describes
9367 how to create a new access method.</p>
9370 This manual does not go into detail about the options and
9371 usage of the package building and installation tools. It
9372 should therefore be read in conjunction with those programs'
9377 The utility programs which are provided with <prgn>dpkg</prgn>
9378 for managing various system configuration and similar issues,
9379 such as <prgn>update-rc.d</prgn> and
9380 <prgn>install-info</prgn>, are not described in detail here -
9381 please see their man pages.
9385 It is assumed that the reader is reasonably familiar with the
9386 <prgn>dpkg</prgn> System Administrators' manual.
9387 Unfortunately this manual does not yet exist.
9391 The Debian version of the FSF's GNU hello program is provided
9392 as an example for people wishing to create Debian
9393 packages. The Debian <prgn>debmake</prgn> package is
9394 recommended as a very helpful tool in creating and maintaining
9395 Debian packages. However, while the tools and examples are
9396 helpful, they do not replace the need to read and follow the
9397 Policy and Programmer's Manual.</p>
9400 <appendix id="pkg-binarypkg">
9401 <heading>Binary packages (from old Packaging Manual)</heading>
9404 The binary package has two main sections. The first part
9405 consists of various control information files and scripts used
9406 by <prgn>dpkg</prgn> when installing and removing. See <ref
9407 id="pkg-controlarea">.
9411 The second part is an archive containing the files and
9412 directories to be installed.
9416 In the future binary packages may also contain other
9417 components, such as checksums and digital signatures. The
9418 format for the archive is described in full in the
9419 <file>deb(5)</file> man page.
9423 <sect id="pkg-bincreating"><heading>Creating package files -
9424 <prgn>dpkg-deb</prgn>
9428 All manipulation of binary package files is done by
9429 <prgn>dpkg-deb</prgn>; it's the only program that has
9430 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9431 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9432 will spot that the options requested are appropriate to
9433 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9438 In order to create a binary package you must make a
9439 directory tree which contains all the files and directories
9440 you want to have in the file system data part of the package.
9441 In Debian-format source packages this directory is usually
9442 <file>debian/tmp</file>, relative to the top of the package's
9447 They should have the locations (relative to the root of the
9448 directory tree you're constructing) ownerships and
9449 permissions which you want them to have on the system when
9454 With current versions of <prgn>dpkg</prgn> the uid/username
9455 and gid/groupname mappings for the users and groups being
9456 used should be the same on the system where the package is
9457 built and the one where it is installed.
9461 You need to add one special directory to the root of the
9462 miniature file system tree you're creating:
9463 <prgn>DEBIAN</prgn>. It should contain the control
9464 information files, notably the binary package control file
9465 (see <ref id="pkg-controlfile">).
9469 The <prgn>DEBIAN</prgn> directory will not appear in the
9470 file system archive of the package, and so won't be installed
9471 by <prgn>dpkg</prgn> when the package is installed.
9475 When you've prepared the package, you should invoke:
9477 dpkg --build <var>directory</var>
9482 This will build the package in
9483 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9484 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9485 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9490 See the man page <manref name="dpkg-deb" section="8"> for details of how
9491 to examine the contents of this newly-created file. You may find the
9492 output of following commands enlightening:
9494 dpkg-deb --info <var>filename</var>.deb
9495 dpkg-deb --contents <var>filename</var>.deb
9496 dpkg --contents <var>filename</var>.deb
9498 To view the copyright file for a package you could use this command:
9500 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
9505 <sect id="pkg-controlarea">
9506 <heading>Package control information files</heading>
9509 The control information portion of a binary package is a
9510 collection of files with names known to <prgn>dpkg</prgn>.
9511 It will treat the contents of these files specially - some
9512 of them contain information used by <prgn>dpkg</prgn> when
9513 installing or removing the package; others are scripts which
9514 the package maintainer wants <prgn>dpkg</prgn> to run.
9518 It is possible to put other files in the package control
9519 area, but this is not generally a good idea (though they
9520 will largely be ignored).
9524 Here is a brief list of the control info files supported by
9525 <prgn>dpkg</prgn> and a summary of what they're used for.
9530 <tag><tt>control</tt>
9533 This is the key description file used by
9534 <prgn>dpkg</prgn>. It specifies the package's name
9535 and version, gives its description for the user,
9536 states its relationships with other packages, and so
9537 forth. See <ref id="sourcecontrolfiles"> and
9538 <ref id="binarycontrolfiles">.
9542 It is usually generated automatically from information
9543 in the source package by the
9544 <prgn>dpkg-gencontrol</prgn> program, and with
9545 assistance from <prgn>dpkg-shlibdeps</prgn>.
9546 See <ref id="pkg-sourcetools">.
9550 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9555 These are executable files (usually scripts) which
9556 <prgn>dpkg</prgn> runs during installation, upgrade
9557 and removal of packages. They allow the package to
9558 deal with matters which are particular to that package
9559 or require more complicated processing than that
9560 provided by <prgn>dpkg</prgn>. Details of when and
9561 how they are called are in <ref id="maintainerscripts">.
9565 It is very important to make these scripts idempotent.
9566 See <ref id="idempotency">.
9570 The maintainer scripts are not guaranteed to run with a
9571 controlling terminal and may not be able to interact with
9572 the user. See <ref id="controllingterminal">.
9576 <tag><tt>conffiles</tt>
9579 This file contains a list of configuration files which
9580 are to be handled automatically by <prgn>dpkg</prgn>
9581 (see <ref id="pkg-conffiles">). Note that not necessarily
9582 every configuration file should be listed here.
9585 <tag><tt>shlibs</tt>
9588 This file contains a list of the shared libraries
9589 supplied by the package, with dependency details for
9590 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9591 when it determines what dependencies are required in a
9592 package control file. The <tt>shlibs</tt> file format
9593 is described on <ref id="shlibs">.
9598 <sect id="pkg-controlfile">
9599 <heading>The main control information file: <tt>control</tt></heading>
9602 The most important control information file used by
9603 <prgn>dpkg</prgn> when it installs a package is
9604 <tt>control</tt>. It contains all the package's "vital
9609 The binary package control files of packages built from
9610 Debian sources are made by a special tool,
9611 <prgn>dpkg-gencontrol</prgn>, which reads
9612 <file>debian/control</file> and <file>debian/changelog</file> to
9613 find the information it needs. See <ref id="pkg-sourcepkg"> for
9618 The fields in binary package control files are listed in
9619 <ref id="binarycontrolfiles">.
9623 A description of the syntax of control files and the purpose
9624 of the fields is available in <ref id="controlfields">.
9629 <heading>Time Stamps</heading>
9632 See <ref id="timestamps">.
9637 <appendix id="pkg-sourcepkg">
9638 <heading>Source packages (from old Packaging Manual) </heading>
9641 The Debian binary packages in the distribution are generated
9642 from Debian sources, which are in a special format to assist
9643 the easy and automatic building of binaries.
9646 <sect id="pkg-sourcetools">
9647 <heading>Tools for processing source packages</heading>
9650 Various tools are provided for manipulating source packages;
9651 they pack and unpack sources and help build of binary
9652 packages and help manage the distribution of new versions.
9656 They are introduced and typical uses described here; see
9657 <manref name="dpkg-source" section="1"> for full
9658 documentation about their arguments and operation.
9662 For examples of how to construct a Debian source package,
9663 and how to use those utilities that are used by Debian
9664 source packages, please see the <prgn>hello</prgn> example
9668 <sect1 id="pkg-dpkg-source">
9670 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
9675 This program is frequently used by hand, and is also
9676 called from package-independent automated building scripts
9677 such as <prgn>dpkg-buildpackage</prgn>.
9681 To unpack a package it is typically invoked with
9683 dpkg-source -x <var>.../path/to/filename</var>.dsc
9688 with the <file><var>filename</var>.tar.gz</file> and
9689 <file><var>filename</var>.diff.gz</file> (if applicable) in
9690 the same directory. It unpacks into
9691 <file><var>package</var>-<var>version</var></file>, and if
9693 <file><var>package</var>-<var>version</var>.orig</file>, in
9694 the current directory.
9698 To create a packed source archive it is typically invoked:
9700 dpkg-source -b <var>package</var>-<var>version</var>
9705 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
9706 <file>.diff.gz</file> (if appropriate) in the current
9707 directory. <prgn>dpkg-source</prgn> does not clean the
9708 source tree first - this must be done separately if it is
9713 See also <ref id="pkg-sourcearchives">.</p>
9717 <sect1 id="pkg-dpkg-buildpackage">
9719 <prgn>dpkg-buildpackage</prgn> - overall package-building
9724 <prgn>dpkg-buildpackage</prgn> is a script which invokes
9725 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
9726 targets <tt>clean</tt>, <tt>build</tt> and
9727 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
9728 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
9729 source and binary package upload.
9733 It is usually invoked by hand from the top level of the
9734 built or unbuilt source directory. It may be invoked with
9735 no arguments; useful arguments include:
9736 <taglist compact="compact">
9737 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
9740 Do not sign the <tt>.changes</tt> file or the
9741 source package <tt>.dsc</tt> file, respectively.</p>
9743 <tag><tt>-p<var>sign-command</var></tt></tag>
9746 Invoke <var>sign-command</var> instead of finding
9747 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
9748 <var>sign-command</var> must behave just like
9749 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9751 <tag><tt>-r<var>root-command</var></tt></tag>
9754 When root privilege is required, invoke the command
9755 <var>root-command</var>. <var>root-command</var>
9756 should invoke its first argument as a command, from
9757 the <prgn>PATH</prgn> if necessary, and pass its
9758 second and subsequent arguments to the command it
9759 calls. If no <var>root-command</var> is supplied
9760 then <var>dpkg-buildpackage</var> will take no
9761 special action to gain root privilege, so that for
9762 most packages it will have to be invoked as root to
9765 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9768 Two types of binary-only build and upload - see
9769 <manref name="dpkg-source" section="1">.
9776 <sect1 id="pkg-dpkg-gencontrol">
9778 <prgn>dpkg-gencontrol</prgn> - generates binary package
9783 This program is usually called from <file>debian/rules</file>
9784 (see <ref id="pkg-sourcetree">) in the top level of the source
9789 This is usually done just before the files and directories in the
9790 temporary directory tree where the package is being built have their
9791 permissions and ownerships set and the package is constructed using
9792 <prgn>dpkg-deb/</prgn>
9794 This is so that the control file which is produced has
9795 the right permissions
9800 <prgn>dpkg-gencontrol</prgn> must be called after all the
9801 files which are to go into the package have been placed in
9802 the temporary build directory, so that its calculation of
9803 the installed size of a package is correct.
9807 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9808 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9809 variable substitutions created by
9810 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9815 For a package which generates only one binary package, and
9816 which builds it in <file>debian/tmp</file> relative to the top
9817 of the source package, it is usually sufficient to call
9818 <prgn>dpkg-gencontrol</prgn>.
9822 Sources which build several binaries will typically need
9825 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9826 </example> The <tt>-P</tt> tells
9827 <prgn>dpkg-gencontrol</prgn> that the package is being
9828 built in a non-default directory, and the <tt>-p</tt>
9829 tells it which package's control file should be generated.
9833 <prgn>dpkg-gencontrol</prgn> also adds information to the
9834 list of files in <file>debian/files</file>, for the benefit of
9835 (for example) a future invocation of
9836 <prgn>dpkg-genchanges</prgn>.</p>
9839 <sect1 id="pkg-dpkg-shlibdeps">
9841 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9846 This program is usually called from <file>debian/rules</file>
9847 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9848 id="pkg-sourcetree">), in the top level of the source tree.
9852 Its arguments are executables and shared libraries
9855 They may be specified either in the locations in the
9856 source tree where they are created or in the locations
9857 in the temporary build tree where they are installed
9858 prior to binary package creation.
9860 </footnote> for which shared library dependencies should
9861 be included in the binary package's control file.
9865 If some of the found shared libraries should only
9866 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9867 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9868 by using the <tt>-d<var>dependency-field</var></tt> option
9869 before those executable(s). (Each <tt>-d</tt> option
9870 takes effect until the next <tt>-d</tt>.)
9874 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9875 output control file to be modified. Instead by default it
9876 adds to the <file>debian/substvars</file> file variable
9877 settings like <tt>shlibs:Depends</tt>. These variable
9878 settings must be referenced in dependency fields in the
9879 appropriate per-binary-package sections of the source
9884 For example, a package that generates an essential part
9885 which requires dependencies, and optional parts that
9886 which only require a recommendation, would separate those
9887 two sets of dependencies into two different fields.<footnote>
9888 At the time of writing, an example for this was the
9889 <package/xmms/ package, with Depends used for the xmms
9890 executable, Recommends for the plug-ins and Suggests for
9891 even more optional features provided by unzip.
9893 It can say in its <file>debian/rules</file>:
9895 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9896 -dRecommends <var>optionalpart anotheroptionalpart</var>
9898 and then in its main control file <file>debian/control</file>:
9901 Depends: ${shlibs:Depends}
9902 Recommends: ${shlibs:Recommends}
9908 Sources which produce several binary packages with
9909 different shared library dependency requirements can use
9910 the <tt>-p<var>varnameprefix</var></tt> option to override
9911 the default <tt>shlibs:</tt> prefix (one invocation of
9912 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9913 They can thus produce several sets of dependency
9914 variables, each of the form
9915 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9916 which can be referred to in the appropriate parts of the
9917 binary package control files.
9922 <sect1 id="pkg-dpkg-distaddfile">
9924 <prgn>dpkg-distaddfile</prgn> - adds a file to
9925 <file>debian/files</file>
9929 Some packages' uploads need to include files other than
9930 the source and binary package files.
9934 <prgn>dpkg-distaddfile</prgn> adds a file to the
9935 <file>debian/files</file> file so that it will be included in
9936 the <file>.changes</file> file when
9937 <prgn>dpkg-genchanges</prgn> is run.
9941 It is usually invoked from the <tt>binary</tt> target of
9942 <file>debian/rules</file>:
9944 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9946 The <var>filename</var> is relative to the directory where
9947 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9948 is usually the directory above the top level of the source
9949 tree. The <file>debian/rules</file> target should put the
9950 file there just before or just after calling
9951 <prgn>dpkg-distaddfile</prgn>.
9955 The <var>section</var> and <var>priority</var> are passed
9956 unchanged into the resulting <file>.changes</file> file.
9961 <sect1 id="pkg-dpkg-genchanges">
9963 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9968 This program is usually called by package-independent
9969 automatic building scripts such as
9970 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9975 It is usually called in the top level of a built source
9976 tree, and when invoked with no arguments will print out a
9977 straightforward <file>.changes</file> file based on the
9978 information in the source package's changelog and control
9979 file and the binary and source packages which should have
9985 <sect1 id="pkg-dpkg-parsechangelog">
9987 <prgn>dpkg-parsechangelog</prgn> - produces parsed
9988 representation of a changelog
9992 This program is used internally by
9993 <prgn>dpkg-source</prgn> et al. It may also occasionally
9994 be useful in <file>debian/rules</file> and elsewhere. It
9995 parses a changelog, <file>debian/changelog</file> by default,
9996 and prints a control-file format representation of the
9997 information in it to standard output.
10001 <sect1 id="pkg-dpkg-architecture">
10003 <prgn>dpkg-architecture</prgn> - information about the build and
10008 This program can be used manually, but is also invoked by
10009 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
10010 environment or make variables which specify the build and host
10011 architecture for the package building process.
10016 <sect id="pkg-sourcetree">
10017 <heading>The Debianised source tree</heading>
10020 The source archive scheme described later is intended to
10021 allow a Debianised source tree with some associated control
10022 information to be reproduced and transported easily. The
10023 Debianised source tree is a version of the original program
10024 with certain files added for the benefit of the
10025 Debianisation process, and with any other changes required
10026 made to the rest of the source code and installation
10031 The extra files created for Debian are in the subdirectory
10032 <file>debian</file> of the top level of the Debianised source
10033 tree. They are described below.
10036 <sect1 id="pkg-debianrules">
10037 <heading><file>debian/rules</file> - the main building script</heading>
10040 See <ref id="debianrules">.
10044 <sect1 id="pkg-srcsubstvars">
10045 <heading><file>debian/substvars</file> and variable substitutions</heading>
10048 See <ref id="substvars">.
10054 <heading><file>debian/files</file></heading>
10057 See <ref id="debianfiles">.
10061 <sect1><heading><file>debian/tmp</file>
10065 This is the canonical temporary location for the
10066 construction of binary packages by the <tt>binary</tt>
10067 target. The directory <file>tmp</file> serves as the root of
10068 the file system tree as it is being constructed (for
10069 example, by using the package's upstream makefiles install
10070 targets and redirecting the output there), and it also
10071 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10072 id="pkg-bincreating">.
10076 If several binary packages are generated from the same
10077 source tree it is usual to use several
10078 <file>debian/tmp<var>something</var></file> directories, for
10079 example <file>tmp-a</file> or <file>tmp-doc</file>.
10083 Whatever <file>tmp</file> directories are created and used by
10084 <tt>binary</tt> must of course be removed by the
10085 <tt>clean</tt> target.</p></sect1>
10089 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10093 As it exists on the FTP site, a Debian source package
10094 consists of three related files. You must have the right
10095 versions of all three to be able to use them.
10100 <tag>Debian source control file - <tt>.dsc</tt></tag>
10102 This file is a control file used by <prgn>dpkg-source</prgn>
10103 to extract a source package.
10104 See <ref id="debiansourcecontrolfiles">.
10108 Original source archive -
10110 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10116 This is a compressed (with <tt>gzip -9</tt>)
10117 <prgn>tar</prgn> file containing the source code from
10118 the upstream authors of the program.
10123 Debianisation diff -
10125 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10131 This is a unified context diff (<tt>diff -u</tt>)
10132 giving the changes which are required to turn the
10133 original source into the Debian source. These changes
10134 may only include editing and creating plain files.
10135 The permissions of files, the targets of symbolic
10136 links and the characteristics of special files or
10137 pipes may not be changed and no files may be removed
10142 All the directories in the diff must exist, except the
10143 <file>debian</file> subdirectory of the top of the source
10144 tree, which will be created by
10145 <prgn>dpkg-source</prgn> if necessary when unpacking.
10149 The <prgn>dpkg-source</prgn> program will
10150 automatically make the <file>debian/rules</file> file
10151 executable (see below).</p></item>
10156 If there is no original source code - for example, if the
10157 package is specially prepared for Debian or the Debian
10158 maintainer is the same as the upstream maintainer - the
10159 format is slightly different: then there is no diff, and the
10161 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10162 and preferably contains a directory named
10163 <file><var>package</var>-<var>version</var></file>.
10168 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10171 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10172 Debian source package. However, if it is not available it
10173 is possible to unpack a Debian source archive as follows:
10174 <enumlist compact="compact">
10177 Untar the tarfile, which will create a <file>.orig</file>
10181 <p>Rename the <file>.orig</file> directory to
10182 <file><var>package</var>-<var>version</var></file>.</p>
10186 Create the subdirectory <file>debian</file> at the top of
10187 the source tree.</p>
10189 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10191 <item><p>Untar the tarfile again if you want a copy of the original
10192 source code alongside the Debianised version.</p>
10197 It is not possible to generate a valid Debian source archive
10198 without using <prgn>dpkg-source</prgn>. In particular,
10199 attempting to use <prgn>diff</prgn> directly to generate the
10200 <file>.diff.gz</file> file will not work.
10204 <heading>Restrictions on objects in source packages</heading>
10207 The source package may not contain any hard links
10209 This is not currently detected when building source
10210 packages, but only when extracting
10214 Hard links may be permitted at some point in the
10215 future, but would require a fair amount of
10217 </footnote>, device special files, sockets or setuid or
10220 Setgid directories are allowed.
10225 The source packaging tools manage the changes between the
10226 original and Debianised source using <prgn>diff</prgn> and
10227 <prgn>patch</prgn>. Turning the original source tree as
10228 included in the <file>.orig.tar.gz</file> into the debianised
10229 source must not involve any changes which cannot be
10230 handled by these tools. Problematic changes which cause
10231 <prgn>dpkg-source</prgn> to halt with an error when
10232 building the source package are:
10233 <list compact="compact">
10234 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10236 <item><p>Changing the targets of symbolic links.</p>
10238 <item><p>Creating directories, other than <file>debian</file>.</p>
10240 <item><p>Changes to the contents of binary files.</p></item>
10241 </list> Changes which cause <prgn>dpkg-source</prgn> to
10242 print a warning but continue anyway are:
10243 <list compact="compact">
10246 Removing files, directories or symlinks.
10248 Renaming a file is not treated specially - it is
10249 seen as the removal of the old file (which
10250 generates a warning, but is otherwise ignored),
10251 and the creation of the new one.
10257 Changed text files which are missing the usual final
10258 newline (either in the original or the modified
10263 Changes which are not represented, but which are not detected by
10264 <prgn>dpkg-source</prgn>, are:
10265 <list compact="compact">
10266 <item><p>Changing the permissions of files (other than
10267 <file>debian/rules</file>) and directories.</p></item>
10272 The <file>debian</file> directory and <file>debian/rules</file>
10273 are handled specially by <prgn>dpkg-source</prgn> - before
10274 applying the changes it will create the <file>debian</file>
10275 directory, and afterwards it will make
10276 <file>debian/rules</file> world-executable.
10282 <appendix id="pkg-controlfields">
10283 <heading>Control files and their fields (from old Packaging Manual)</heading>
10286 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10287 data in a common format, known as control files. Binary and
10288 source packages have control data as do the <file>.changes</file>
10289 files which control the installation of uploaded files, and
10290 <prgn>dpkg</prgn>'s internal databases are in a similar
10295 <heading>Syntax of control files</heading>
10298 See <ref id="controlsyntax">.
10302 It is important to note that there are several fields which
10303 are optional as far as <prgn>dpkg</prgn> and the related
10304 tools are concerned, but which must appear in every Debian
10305 package, or whose omission may cause problems.
10310 <heading>List of fields</heading>
10313 See <ref id="controlfieldslist">.
10317 This section now contains only the fields that didn't belong
10318 to the Policy manual.
10321 <sect1 id="pkg-f-Filename">
10322 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10325 These fields in <tt>Packages</tt> files give the
10326 filename(s) of (the parts of) a package in the
10327 distribution directories, relative to the root of the
10328 Debian hierarchy. If the package has been split into
10329 several parts the parts are all listed in order, separated
10334 <sect1 id="pkg-f-Size">
10335 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10338 These fields in <file>Packages</file> files give the size (in
10339 bytes, expressed in decimal) and MD5 checksum of the
10340 file(s) which make(s) up a binary package in the
10341 distribution. If the package is split into several parts
10342 the values for the parts are listed in order, separated by
10347 <sect1 id="pkg-f-Status">
10348 <heading><tt>Status</tt></heading>
10351 This field in <prgn>dpkg</prgn>'s status file records
10352 whether the user wants a package installed, removed or
10353 left alone, whether it is broken (requiring
10354 re-installation) or not and what its current state on the
10355 system is. Each of these pieces of information is a
10360 <sect1 id="pkg-f-Config-Version">
10361 <heading><tt>Config-Version</tt></heading>
10364 If a package is not installed or not configured, this
10365 field in <prgn>dpkg</prgn>'s status file records the last
10366 version of the package which was successfully
10371 <sect1 id="pkg-f-Conffiles">
10372 <heading><tt>Conffiles</tt></heading>
10375 This field in <prgn>dpkg</prgn>'s status file contains
10376 information about the automatically-managed configuration
10377 files held by a package. This field should <em>not</em>
10378 appear anywhere in a package!
10383 <heading>Obsolete fields</heading>
10386 These are still recognized by <prgn>dpkg</prgn> but should
10387 not appear anywhere any more.
10389 <taglist compact="compact">
10391 <tag><tt>Revision</tt></tag>
10392 <tag><tt>Package-Revision</tt></tag>
10393 <tag><tt>Package_Revision</tt></tag>
10395 The Debian revision part of the package version was
10396 at one point in a separate control file field. This
10397 field went through several names.
10400 <tag><tt>Recommended</tt></tag>
10401 <item>Old name for <tt>Recommends</tt>.</item>
10403 <tag><tt>Optional</tt></tag>
10404 <item>Old name for <tt>Suggests</tt>.</item>
10406 <tag><tt>Class</tt></tag>
10407 <item>Old name for <tt>Priority</tt>.</item>
10416 <appendix id="pkg-conffiles">
10417 <heading>Configuration file handling (from old Packaging Manual)</heading>
10420 <prgn>dpkg</prgn> can do a certain amount of automatic
10421 handling of package configuration files.
10425 Whether this mechanism is appropriate depends on a number of
10426 factors, but basically there are two approaches to any
10427 particular configuration file.
10431 The easy method is to ship a best-effort configuration in the
10432 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10433 handle updates. If the user is unlikely to want to edit the
10434 file, but you need them to be able to without losing their
10435 changes, and a new package with a changed version of the file
10436 is only released infrequently, this is a good approach.
10440 The hard method is to build the configuration file from
10441 scratch in the <prgn>postinst</prgn> script, and to take the
10442 responsibility for fixing any mistakes made in earlier
10443 versions of the package automatically. This will be
10444 appropriate if the file is likely to need to be different on
10448 <sect><heading>Automatic handling of configuration files by
10453 A package may contain a control area file called
10454 <tt>conffiles</tt>. This file should be a list of filenames
10455 of configuration files needing automatic handling, separated
10456 by newlines. The filenames should be absolute pathnames,
10457 and the files referred to should actually exist in the
10462 When a package is upgraded <prgn>dpkg</prgn> will process
10463 the configuration files during the configuration stage,
10464 shortly before it runs the package's <prgn>postinst</prgn>
10469 For each file it checks to see whether the version of the
10470 file included in the package is the same as the one that was
10471 included in the last version of the package (the one that is
10472 being upgraded from); it also compares the version currently
10473 installed on the system with the one shipped with the last
10478 If neither the user nor the package maintainer has changed
10479 the file, it is left alone. If one or the other has changed
10480 their version, then the changed version is preferred - i.e.,
10481 if the user edits their file, but the package maintainer
10482 doesn't ship a different version, the user's changes will
10483 stay, silently, but if the maintainer ships a new version
10484 and the user hasn't edited it the new version will be
10485 installed (with an informative message). If both have
10486 changed their version the user is prompted about the problem
10487 and must resolve the differences themselves.
10491 The comparisons are done by calculating the MD5 message
10492 digests of the files, and storing the MD5 of the file as it
10493 was included in the most recent version of the package.
10497 When a package is installed for the first time
10498 <prgn>dpkg</prgn> will install the file that comes with it,
10499 unless that would mean overwriting a file already on the
10504 However, note that <prgn>dpkg</prgn> will <em>not</em>
10505 replace a conffile that was removed by the user (or by a
10506 script). This is necessary because with some programs a
10507 missing file produces an effect hard or impossible to
10508 achieve in another way, so that a missing file needs to be
10509 kept that way if the user did it.
10513 Note that a package should <em>not</em> modify a
10514 <prgn>dpkg</prgn>-handled conffile in its maintainer
10515 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10516 the user confusing and possibly dangerous options for
10517 conffile update when the package is upgraded.</p>
10520 <sect><heading>Fully-featured maintainer script configuration
10525 For files which contain site-specific information such as
10526 the hostname and networking details and so forth, it is
10527 better to create the file in the package's
10528 <prgn>postinst</prgn> script.
10532 This will typically involve examining the state of the rest
10533 of the system to determine values and other information, and
10534 may involve prompting the user for some information which
10535 can't be obtained some other way.
10539 When using this method there are a couple of important
10540 issues which should be considered:
10544 If you discover a bug in the program which generates the
10545 configuration file, or if the format of the file changes
10546 from one version to the next, you will have to arrange for
10547 the postinst script to do something sensible - usually this
10548 will mean editing the installed configuration file to remove
10549 the problem or change the syntax. You will have to do this
10550 very carefully, since the user may have changed the file,
10551 perhaps to fix the very problem that your script is trying
10552 to deal with - you will have to detect these situations and
10553 deal with them correctly.
10557 If you do go down this route it's probably a good idea to
10558 make the program that generates the configuration file(s) a
10559 separate program in <file>/usr/sbin</file>, by convention called
10560 <file><var>package</var>config</file> and then run that if
10561 appropriate from the post-installation script. The
10562 <tt><var>package</var>config</tt> program should not
10563 unquestioningly overwrite an existing configuration - if its
10564 mode of operation is geared towards setting up a package for
10565 the first time (rather than any arbitrary reconfiguration
10566 later) you should have it check whether the configuration
10567 already exists, and require a <tt>--force</tt> flag to
10568 overwrite it.</p></sect>
10571 <appendix id="pkg-alternatives"><heading>Alternative versions of
10572 an interface - <prgn>update-alternatives</prgn> (from old
10577 When several packages all provide different versions of the
10578 same program or file it is useful to have the system select a
10579 default, but to allow the system administrator to change it
10580 and have their decisions respected.
10584 For example, there are several versions of the <prgn>vi</prgn>
10585 editor, and there is no reason to prevent all of them from
10586 being installed at once, each under their own name
10587 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10588 Nevertheless it is desirable to have the name <tt>vi</tt>
10589 refer to something, at least by default.
10593 If all the packages involved cooperate, this can be done with
10594 <prgn>update-alternatives</prgn>.
10598 Each package provides its own version under its own name, and
10599 calls <prgn>update-alternatives</prgn> in its postinst to
10600 register its version (and again in its prerm to deregister
10605 See the man page <manref name="update-alternatives"
10606 section="8"> for details.
10610 If <prgn>update-alternatives</prgn> does not seem appropriate
10611 you may wish to consider using diversions instead.</p>
10614 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10615 package's version of a file (from old Packaging Manual)
10619 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10620 when it reinstalls the package it belongs to, and to have it
10621 put the file from the package somewhere else instead.
10625 This can be used locally to override a package's version of a
10626 file, or by one package to override another's version (or
10627 provide a wrapper for it).
10631 Before deciding to use a diversion, read <ref
10632 id="pkg-alternatives"> to see if you really want a diversion
10633 rather than several alternative versions of a program.
10637 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10638 and updated by a special program <prgn>dpkg-divert</prgn>.
10639 Please see <manref name="dpkg-divert" section="8"> for full
10640 details of its operation.
10644 When a package wishes to divert a file from another, it should
10645 call <prgn>dpkg-divert</prgn> in its preinst to add the
10646 diversion and rename the existing file. For example,
10647 supposing that a <prgn>smailwrapper</prgn> package wishes to
10648 install a wrapper around <file>/usr/sbin/smail</file>:
10650 dpkg-divert --package smailwrapper --add --rename \
10651 --divert /usr/sbin/smail.real /usr/sbin/smail
10652 </example> The <tt>--package smailwrapper</tt> ensures that
10653 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
10654 can bypass the diversion and get installed as the true version.
10655 It's safe to add the diversion unconditionally on upgrades since
10656 it will be left unchanged if it already exists, but
10657 <prgn>dpkg-divert</prgn> will display a message. To suppress that
10658 message, make the command conditional on the version from which
10659 the package is being upgraded:
10661 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
10662 dpkg-divert --package smailwrapper --add --rename \
10663 --divert /usr/sbin/smail.real /usr/sbin/smail
10665 </example> where <tt>1.0-2</tt> is the version at which the
10666 diversion was first added to the package. Running the command
10667 during abort-upgrade is pointless but harmless.
10671 The postrm has to do the reverse:
10673 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
10674 dpkg-divert --package smailwrapper --remove --rename \
10675 --divert /usr/sbin/smail.real /usr/sbin/smail
10677 </example> If the diversion was added at a particular version, the
10678 postrm should also handle the failure case of upgrading from an
10679 older version (unless the older version is so old that direct
10680 upgrades are no longer supported):
10682 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
10683 dpkg-divert --package smailwrapper --remove --rename \
10684 --divert /usr/sbin/smail.real /usr/sbin/smail
10686 </example> where <tt>1.02-2</tt> is the version at which the
10687 diversion was first added to the package. The postrm should not
10688 remove the diversion on upgrades both because there's no reason to
10689 remove the diversion only to immediately re-add it and since the
10690 postrm of the old package is run after unpacking so the removal of
10691 the diversion will fail.
10695 Do not attempt to divert a file which is vitally important for
10696 the system's operation - when using <prgn>dpkg-divert</prgn>
10697 there is a time, after it has been diverted but before
10698 <prgn>dpkg</prgn> has installed the new version, when the file
10699 does not exist.</p>
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