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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> has the following format<footnote>
1622 This is the same as the format generated by <tt>date
1624 </footnote> (compatible and with the same semantics of
1625 RFC 2822 and RFC 5322):
1626 <example>day-of-week, dd month yyyy hh:mm:ss +zzzz</example>
1628 <list compact="compact">
1630 day-of week is one of: Mon, Tue, Wed, Thu, Fri, Sat, Sun
1633 dd is a one- or two-digit day of the month (01-31)
1636 month is one of: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug,
1639 <item>yyyy is the four-digit year (e.g. 2010)</item>
1640 <item>hh is the two-digit hour (00-23)</item>
1641 <item>mm is the two-digit minutes (00-59)</item>
1642 <item>ss is the two-digit seconds (00-60)</item>
1644 +zzzz or -zzzz is the the time zone offset from Coordinated
1645 Universal Time (UTC). "+" indicates that the time is ahead
1646 of (i.e., east of) UTC and "-" indicates that the time is
1647 behind (i.e., west of) UTC. The first two digits indicate
1648 the hour difference from UTC and the last two digits
1649 indicate the number of additional minutes difference from
1650 UTC. The last two digits must be in the range 00-59.
1656 The first "title" line with the package name must start
1657 at the left hand margin. The "trailer" line with the
1658 maintainer and date details must be preceded by exactly
1659 one space. The maintainer details and the date must be
1660 separated by exactly two spaces.
1664 The entire changelog must be encoded in UTF-8.
1668 For more information on placement of the changelog files
1669 within binary packages, please see <ref id="changelogs">.
1673 <sect id="dpkgcopyright">
1674 <heading>Copyright: <file>debian/copyright</file></heading>
1676 Every package must be accompanied by a verbatim copy of its
1677 copyright information and distribution license in the file
1678 <file>/usr/share/doc/<var>package</var>/copyright</file>
1679 (see <ref id="copyrightfile"> for further details). Also see
1680 <ref id="pkgcopyright"> for further considerations related
1681 to copyrights for packages.
1685 <heading>Error trapping in makefiles</heading>
1688 When <prgn>make</prgn> invokes a command in a makefile
1689 (including your package's upstream makefiles and
1690 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1691 means that <prgn>sh</prgn>'s usual bad error handling
1692 properties apply: if you include a miniature script as one
1693 of the commands in your makefile you'll find that if you
1694 don't do anything about it then errors are not detected
1695 and <prgn>make</prgn> will blithely continue after
1700 Every time you put more than one shell command (this
1701 includes using a loop) in a makefile command you
1702 must make sure that errors are trapped. For
1703 simple compound commands, such as changing directory and
1704 then running a program, using <tt>&&</tt> rather
1705 than semicolon as a command separator is sufficient. For
1706 more complex commands including most loops and
1707 conditionals you should include a separate <tt>set -e</tt>
1708 command at the start of every makefile command that's
1709 actually one of these miniature shell scripts.
1713 <sect id="timestamps">
1714 <heading>Time Stamps</heading>
1716 Maintainers should preserve the modification times of the
1717 upstream source files in a package, as far as is reasonably
1719 The rationale is that there is some information conveyed
1720 by knowing the age of the file, for example, you could
1721 recognize that some documentation is very old by looking
1722 at the modification time, so it would be nice if the
1723 modification time of the upstream source would be
1729 <sect id="restrictions">
1730 <heading>Restrictions on objects in source packages</heading>
1733 The source package may not contain any hard links<footnote>
1735 This is not currently detected when building source
1736 packages, but only when extracting
1740 Hard links may be permitted at some point in the
1741 future, but would require a fair amount of
1744 </footnote>, device special files, sockets or setuid or
1745 setgid files.<footnote>
1746 Setgid directories are allowed.
1751 <sect id="debianrules">
1752 <heading>Main building script: <file>debian/rules</file></heading>
1755 This file must be an executable makefile, and contains the
1756 package-specific recipes for compiling the package and
1757 building binary package(s) from the source.
1761 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1762 so that it can be invoked by saying its name rather than
1763 invoking <prgn>make</prgn> explicitly. That is, invoking
1764 either of <tt>make -f debian/rules <em>args...</em></tt>
1765 or <tt>./debian/rules <em>args...</em></tt> must result in
1770 Since an interactive <file>debian/rules</file> script makes it
1771 impossible to auto-compile that package and also makes it
1772 hard for other people to reproduce the same binary
1773 package, all <em>required targets</em> must be
1774 non-interactive. At a minimum, required targets are the
1775 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1776 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1777 <em>binary-indep</em>, and <em>build</em>. It also follows
1778 that any target that these targets depend on must also be
1783 The targets are as follows (required unless stated otherwise):
1785 <tag><tt>build</tt></tag>
1788 The <tt>build</tt> target should perform all the
1789 configuration and compilation of the package.
1790 If a package has an interactive pre-build
1791 configuration routine, the Debianized source package
1792 must either be built after this has taken place (so
1793 that the binary package can be built without rerunning
1794 the configuration) or the configuration routine
1795 modified to become non-interactive. (The latter is
1796 preferable if there are architecture-specific features
1797 detected by the configuration routine.)
1801 For some packages, notably ones where the same
1802 source tree is compiled in different ways to produce
1803 two binary packages, the <tt>build</tt> target
1804 does not make much sense. For these packages it is
1805 good enough to provide two (or more) targets
1806 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1807 for each of the ways of building the package, and a
1808 <tt>build</tt> target that does nothing. The
1809 <tt>binary</tt> target will have to build the
1810 package in each of the possible ways and make the
1811 binary package out of each.
1815 The <tt>build</tt> target must not do anything
1816 that might require root privilege.
1820 The <tt>build</tt> target may need to run the
1821 <tt>clean</tt> target first - see below.
1825 When a package has a configuration and build routine
1826 which takes a long time, or when the makefiles are
1827 poorly designed, or when <tt>build</tt> needs to
1828 run <tt>clean</tt> first, it is a good idea to
1829 <tt>touch build</tt> when the build process is
1830 complete. This will ensure that if <tt>debian/rules
1831 build</tt> is run again it will not rebuild the whole
1833 Another common way to do this is for <tt>build</tt>
1834 to depend on <prgn>build-stamp</prgn> and to do
1835 nothing else, and for the <prgn>build-stamp</prgn>
1836 target to do the building and to <tt>touch
1837 build-stamp</tt> on completion. This is
1838 especially useful if the build routine creates a
1839 file or directory called <tt>build</tt>; in such a
1840 case, <tt>build</tt> will need to be listed as
1841 a phony target (i.e., as a dependency of the
1842 <tt>.PHONY</tt> target). See the documentation of
1843 <prgn>make</prgn> for more information on phony
1849 <tag><tt>build-arch</tt> (optional),
1850 <tt>build-indep</tt> (optional)
1854 A package may also provide both of the targets
1855 <tt>build-arch</tt> and <tt>build-indep</tt>.
1856 The <tt>build-arch</tt> target, if provided, should
1857 perform all the configuration and compilation required for
1858 producing all architecture-dependant binary packages
1859 (those packages for which the body of the
1860 <tt>Architecture</tt> field in <tt>debian/control</tt> is
1861 not <tt>all</tt>). Similarly, the <tt>build-indep</tt>
1862 target, if provided, should perform all the configuration
1863 and compilation required for producing all
1864 architecture-independent binary packages (those packages
1865 for which the body of the <tt>Architecture</tt> field
1866 in <tt>debian/control</tt> is <tt>all</tt>).
1867 The <tt>build</tt> target should depend on those of the
1868 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1869 are provided in the rules file.<footnote>
1870 The intent of this split is so that binary-only builds
1871 need not install the dependencies required for
1872 the <tt>build-indep</tt> target. However, this is not
1873 yet used in practice since <tt>dpkg-buildpackage
1874 -B</tt>, and therefore the autobuilders,
1875 invoke <tt>build</tt> rather than <tt>build-arch</tt>
1876 due to the difficulties in determining whether the
1877 optional <tt>build-arch</tt> target exists.
1882 If one or both of the targets <tt>build-arch</tt> and
1883 <tt>build-indep</tt> are not provided, then invoking
1884 <file>debian/rules</file> with one of the not-provided
1885 targets as arguments should produce a exit status code
1886 of 2. Usually this is provided automatically by make
1887 if the target is missing.
1891 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1892 must not do anything that might require root privilege.
1896 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1897 <tt>binary-indep</tt>
1901 The <tt>binary</tt> target must be all that is
1902 necessary for the user to build the binary package(s)
1903 produced from this source package. It is
1904 split into two parts: <prgn>binary-arch</prgn> builds
1905 the binary packages which are specific to a particular
1906 architecture, and <tt>binary-indep</tt> builds
1907 those which are not.
1910 <tt>binary</tt> may be (and commonly is) a target with
1911 no commands which simply depends on
1912 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1915 Both <tt>binary-*</tt> targets should depend on the
1916 <tt>build</tt> target, or on the appropriate
1917 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1918 provided, so that the package is built if it has not
1919 been already. It should then create the relevant
1920 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1921 make their control files and <prgn>dpkg-deb</prgn> to
1922 build them and place them in the parent of the top
1927 Both the <tt>binary-arch</tt> and
1928 <tt>binary-indep</tt> targets <em>must</em> exist.
1929 If one of them has nothing to do (which will always be
1930 the case if the source generates only a single binary
1931 package, whether architecture-dependent or not), it
1932 must still exist and must always succeed.
1936 The <tt>binary</tt> targets must be invoked as
1938 The <prgn>fakeroot</prgn> package often allows one
1939 to build a package correctly even without being
1945 <tag><tt>clean</tt></tag>
1948 This must undo any effects that the <tt>build</tt>
1949 and <tt>binary</tt> targets may have had, except
1950 that it should leave alone any output files created in
1951 the parent directory by a run of a <tt>binary</tt>
1956 If a <tt>build</tt> file is touched at the end of
1957 the <tt>build</tt> target, as suggested above, it
1958 should be removed as the first action that
1959 <tt>clean</tt> performs, so that running
1960 <tt>build</tt> again after an interrupted
1961 <tt>clean</tt> doesn't think that everything is
1966 The <tt>clean</tt> target may need to be
1967 invoked as root if <tt>binary</tt> has been
1968 invoked since the last <tt>clean</tt>, or if
1969 <tt>build</tt> has been invoked as root (since
1970 <tt>build</tt> may create directories, for
1975 <tag><tt>get-orig-source</tt> (optional)</tag>
1978 This target fetches the most recent version of the
1979 original source package from a canonical archive site
1980 (via FTP or WWW, for example), does any necessary
1981 rearrangement to turn it into the original source
1982 tar file format described below, and leaves it in the
1987 This target may be invoked in any directory, and
1988 should take care to clean up any temporary files it
1993 This target is optional, but providing it if
1994 possible is a good idea.
1998 <tag><tt>patch</tt> (optional)</tag>
2001 This target performs whatever additional actions are
2002 required to make the source ready for editing (unpacking
2003 additional upstream archives, applying patches, etc.).
2004 It is recommended to be implemented for any package where
2005 <tt>dpkg-source -x</tt> does not result in source ready
2006 for additional modification. See
2007 <ref id="readmesource">.
2013 The <tt>build</tt>, <tt>binary</tt> and
2014 <tt>clean</tt> targets must be invoked with the current
2015 directory being the package's top-level directory.
2020 Additional targets may exist in <file>debian/rules</file>,
2021 either as published or undocumented interfaces or for the
2022 package's internal use.
2026 The architectures we build on and build for are determined
2027 by <prgn>make</prgn> variables using the utility
2028 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
2029 You can determine the
2030 Debian architecture and the GNU style architecture
2031 specification string for the build machine (the machine type
2032 we are building on) as well as for the host machine (the
2033 machine type we are building for). Here is a list of
2034 supported <prgn>make</prgn> variables:
2035 <list compact="compact">
2037 <tt>DEB_*_ARCH</tt> (the Debian architecture)
2040 <tt>DEB_*_ARCH_CPU</tt> (the Debian CPU name)
2043 <tt>DEB_*_ARCH_OS</tt> (the Debian System name)
2046 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2047 specification string)
2050 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2051 <tt>DEB_*_GNU_TYPE</tt>)
2054 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2055 <tt>DEB_*_GNU_TYPE</tt>)
2057 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2058 the build machine or <tt>HOST</tt> for specification of the
2063 Backward compatibility can be provided in the rules file
2064 by setting the needed variables to suitable default
2065 values; please refer to the documentation of
2066 <prgn>dpkg-architecture</prgn> for details.
2070 It is important to understand that the <tt>DEB_*_ARCH</tt>
2071 string only determines which Debian architecture we are
2072 building on or for. It should not be used to get the CPU
2073 or system information; the <tt>DEB_*_ARCH_CPU</tt> and
2074 <tt>DEB_*_ARCH_OS</tt> variables should be used for that.
2075 GNU style variables should generally only be used with upstream
2079 <sect1 id="debianrules-options">
2080 <heading><file>debian/rules</file> and
2081 <tt>DEB_BUILD_OPTIONS</tt></heading>
2084 Supporting the standardized environment variable
2085 <tt>DEB_BUILD_OPTIONS</tt> is recommended. This variable can
2086 contain several flags to change how a package is compiled and
2087 built. Each flag must be in the form <var>flag</var> or
2088 <var>flag</var>=<var>options</var>. If multiple flags are
2089 given, they must be separated by whitespace.<footnote>
2090 Some packages support any delimiter, but whitespace is the
2091 easiest to parse inside a makefile and avoids ambiguity with
2092 flag values that contain commas.
2094 <var>flag</var> must start with a lowercase letter
2095 (<tt>a-z</tt>) and consist only of lowercase letters,
2096 numbers (<tt>0-9</tt>), and the characters
2097 <tt>-</tt> and <tt>_</tt> (hyphen and underscore).
2098 <var>options</var> must not contain whitespace. The same
2099 tag should not be given multiple times with conflicting
2100 values. Package maintainers may assume that
2101 <tt>DEB_BUILD_OPTIONS</tt> will not contain conflicting tags.
2105 The meaning of the following tags has been standardized:
2109 This tag says to not run any build-time test suite
2110 provided by the package.
2114 The presence of this tag means that the package should
2115 be compiled with a minimum of optimization. For C
2116 programs, it is best to add <tt>-O0</tt> to
2117 <tt>CFLAGS</tt> (although this is usually the default).
2118 Some programs might fail to build or run at this level
2119 of optimization; it may be necessary to use
2120 <tt>-O1</tt>, for example.
2124 This tag means that the debugging symbols should not be
2125 stripped from the binary during installation, so that
2126 debugging information may be included in the package.
2128 <tag>parallel=n</tag>
2130 This tag means that the package should be built using up
2131 to <tt>n</tt> parallel processes if the package build
2132 system supports this.<footnote>
2133 Packages built with <tt>make</tt> can often implement
2134 this by passing the <tt>-j</tt><var>n</var> option to
2137 If the package build system does not support parallel
2138 builds, this string must be ignored. If the package
2139 build system only supports a lower level of concurrency
2140 than <var>n</var>, the package should be built using as
2141 many parallel processes as the package build system
2142 supports. It is up to the package maintainer to decide
2143 whether the package build times are long enough and the
2144 package build system is robust enough to make supporting
2145 parallel builds worthwhile.
2151 Unknown flags must be ignored by <file>debian/rules</file>.
2155 The following makefile snippet is an example of how one may
2156 implement the build options; you will probably have to
2157 massage this example in order to make it work for your
2159 <example compact="compact">
2162 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
2163 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
2164 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
2165 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
2167 ifneq (,$(filter noopt,$(DEB_BUILD_OPTIONS)))
2172 ifeq (,$(filter nostrip,$(DEB_BUILD_OPTIONS)))
2173 INSTALL_PROGRAM += -s
2175 ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2176 NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2177 MAKEFLAGS += -j$(NUMJOBS)
2182 ifeq (,$(filter nocheck,$(DEB_BUILD_OPTIONS)))
2183 # Code to run the package test suite.
2190 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2191 <sect id="substvars">
2192 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2195 When <prgn>dpkg-gencontrol</prgn>,
2196 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2197 generate control files they perform variable substitutions
2198 on their output just before writing it. Variable
2199 substitutions have the form <tt>${<var>variable</var>}</tt>.
2200 The optional file <file>debian/substvars</file> contains
2201 variable substitutions to be used; variables can also be set
2202 directly from <file>debian/rules</file> using the <tt>-V</tt>
2203 option to the source packaging commands, and certain
2204 predefined variables are also available.
2208 The <file>debian/substvars</file> file is usually generated and
2209 modified dynamically by <file>debian/rules</file> targets, in
2210 which case it must be removed by the <tt>clean</tt> target.
2214 See <manref name="deb-substvars" section="5"> for full
2215 details about source variable substitutions, including the
2216 format of <file>debian/substvars</file>.</p>
2219 <sect id="debianwatch">
2220 <heading>Optional upstream source location: <file>debian/watch</file></heading>
2223 This is an optional, recommended control file for the
2224 <tt>uscan</tt> utility which defines how to automatically
2225 scan ftp or http sites for newly available updates of the
2226 package. This is used by <url id="
2227 http://dehs.alioth.debian.org/"> and other Debian QA tools
2228 to help with quality control and maintenance of the
2229 distribution as a whole.
2234 <sect id="debianfiles">
2235 <heading>Generated files list: <file>debian/files</file></heading>
2238 This file is not a permanent part of the source tree; it
2239 is used while building packages to record which files are
2240 being generated. <prgn>dpkg-genchanges</prgn> uses it
2241 when it generates a <file>.changes</file> file.
2245 It should not exist in a shipped source package, and so it
2246 (and any backup files or temporary files such as
2247 <file>files.new</file><footnote>
2248 <file>files.new</file> is used as a temporary file by
2249 <prgn>dpkg-gencontrol</prgn> and
2250 <prgn>dpkg-distaddfile</prgn> - they write a new
2251 version of <tt>files</tt> here before renaming it,
2252 to avoid leaving a corrupted copy if an error
2254 </footnote>) should be removed by the
2255 <tt>clean</tt> target. It may also be wise to
2256 ensure a fresh start by emptying or removing it at the
2257 start of the <tt>binary</tt> target.
2261 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2262 package, it adds an entry to <file>debian/files</file> for the
2263 <file>.deb</file> file that will be created when <tt>dpkg-deb
2264 --build</tt> is run for that binary package. So for most
2265 packages all that needs to be done with this file is to
2266 delete it in the <tt>clean</tt> target.
2270 If a package upload includes files besides the source
2271 package and any binary packages whose control files were
2272 made with <prgn>dpkg-gencontrol</prgn> then they should be
2273 placed in the parent of the package's top-level directory
2274 and <prgn>dpkg-distaddfile</prgn> should be called to add
2275 the file to the list in <file>debian/files</file>.</p>
2278 <sect id="embeddedfiles">
2279 <heading>Convenience copies of code</heading>
2282 Some software packages include in their distribution convenience
2283 copies of code from other software packages, generally so that
2284 users compiling from source don't have to download multiple
2285 packages. Debian packages should not make use of these
2286 convenience copies unless the included package is explicitly
2287 intended to be used in this way.<footnote>
2288 For example, parts of the GNU build system work like this.
2290 If the included code is already in the Debian archive in the
2291 form of a library, the Debian packaging should ensure that
2292 binary packages reference the libraries already in Debian and
2293 the convenience copy is not used. If the included code is not
2294 already in Debian, it should be packaged separately as a
2295 prerequisite if possible.
2297 Having multiple copies of the same code in Debian is
2298 inefficient, often creates either static linking or shared
2299 library conflicts, and, most importantly, increases the
2300 difficulty of handling security vulnerabilities in the
2306 <sect id="readmesource">
2307 <heading>Source package handling:
2308 <file>debian/README.source</file></heading>
2311 If running <prgn>dpkg-source -x</prgn> on a source package
2312 doesn't produce the source of the package, ready for editing,
2313 and allow one to make changes and run
2314 <prgn>dpkg-buildpackage</prgn> to produce a modified package
2315 without taking any additional steps, creating a
2316 <file>debian/README.source</file> documentation file is
2317 recommended. This file should explain how to do all of the
2320 <item>Generate the fully patched source, in a form ready for
2321 editing, that would be built to create Debian
2322 packages. Doing this with a <tt>patch</tt> target in
2323 <file>debian/rules</file> is recommended; see
2324 <ref id="debianrules">.</item>
2325 <item>Modify the source and save those modifications so that
2326 they will be applied when building the package.</item>
2327 <item>Remove source modifications that are currently being
2328 applied when building the package.</item>
2329 <item>Optionally, document what steps are necessary to
2330 upgrade the Debian source package to a new upstream version,
2331 if applicable.</item>
2333 This explanation should include specific commands and mention
2334 any additional required Debian packages. It should not assume
2335 familiarity with any specific Debian packaging system or patch
2340 This explanation may refer to a documentation file installed by
2341 one of the package's build dependencies provided that the
2342 referenced documentation clearly explains these tasks and is not
2343 a general reference manual.
2347 <file>debian/README.source</file> may also include any other
2348 information that would be helpful to someone modifying the
2349 source package. Even if the package doesn't fit the above
2350 description, maintainers are encouraged to document in a
2351 <file>debian/README.source</file> file any source package with a
2352 particularly complex or unintuitive source layout or build
2353 system (for example, a package that builds the same source
2354 multiple times to generate different binary packages).
2360 <chapt id="controlfields">
2361 <heading>Control files and their fields</heading>
2364 The package management system manipulates data represented in
2365 a common format, known as <em>control data</em>, stored in
2366 <em>control files</em>.
2367 Control files are used for source packages, binary packages and
2368 the <file>.changes</file> files which control the installation
2369 of uploaded files<footnote>
2370 <prgn>dpkg</prgn>'s internal databases are in a similar
2375 <sect id="controlsyntax">
2376 <heading>Syntax of control files</heading>
2379 A control file consists of one or more paragraphs of
2381 The paragraphs are also sometimes referred to as stanzas.
2383 The paragraphs are separated by blank lines. Some control
2384 files allow only one paragraph; others allow several, in
2385 which case each paragraph usually refers to a different
2386 package. (For example, in source packages, the first
2387 paragraph refers to the source package, and later paragraphs
2388 refer to binary packages generated from the source.)
2392 Each paragraph consists of a series of data fields; each
2393 field consists of the field name, followed by a colon and
2394 then the data/value associated with that field. It ends at
2395 the end of the (logical) line. Horizontal whitespace
2396 (spaces and tabs) may occur immediately before or after the
2397 value and is ignored there; it is conventional to put a
2398 single space after the colon. For example, a field might
2400 <example compact="compact">
2403 the field name is <tt>Package</tt> and the field value
2408 Many fields' values may span several lines; in this case
2409 each continuation line must start with a space or a tab.
2410 Any trailing spaces or tabs at the end of individual
2411 lines of a field value are ignored.
2415 In fields where it is specified that lines may not wrap,
2416 only a single line of data is allowed and whitespace is not
2417 significant in a field body. Whitespace must not appear
2418 inside names (of packages, architectures, files or anything
2419 else) or version numbers, or between the characters of
2420 multi-character version relationships.
2424 Field names are not case-sensitive, but it is usual to
2425 capitalize the field names using mixed case as shown below.
2426 Field values are case-sensitive unless the description of the
2427 field says otherwise.
2431 Blank lines, or lines consisting only of spaces and tabs,
2432 are not allowed within field values or between fields - that
2433 would mean a new paragraph.
2437 All control files must be encoded in UTF-8.
2441 <sect id="sourcecontrolfiles">
2442 <heading>Source package control files -- <file>debian/control</file></heading>
2445 The <file>debian/control</file> file contains the most vital
2446 (and version-independent) information about the source package
2447 and about the binary packages it creates.
2451 The first paragraph of the control file contains information about
2452 the source package in general. The subsequent sets each describe a
2453 binary package that the source tree builds.
2457 The fields in the general paragraph (the first one, for the source
2460 <list compact="compact">
2461 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2462 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2463 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2464 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2465 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2466 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2467 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2468 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2473 The fields in the binary package paragraphs are:
2475 <list compact="compact">
2476 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2477 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2478 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2479 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2480 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2481 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2482 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2483 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2488 The syntax and semantics of the fields are described below.
2494 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2495 generate control files for binary packages (see below), by
2496 <prgn>dpkg-genchanges</prgn> to generate the
2497 <tt>.changes</tt> file to accompany the upload, and by
2498 <prgn>dpkg-source</prgn> when it creates the
2499 <file>.dsc</file> source control file as part of a source
2500 archive. Many fields are permitted to span multiple lines in
2501 <file>debian/control</file> but not in any other control
2502 file. These tools are responsible for removing the line
2503 breaks from such fields when using fields from
2504 <file>debian/control</file> to generate other control files.
2508 The fields here may contain variable references - their
2509 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2510 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2511 when they generate output control files.
2512 See <ref id="substvars"> for details.
2516 In addition to the control file syntax described <qref
2517 id="controlsyntax">above</qref>, this file may also contain
2518 comment lines starting with <tt>#</tt> without any preceding
2519 whitespace. All such lines are ignored, even in the middle of
2520 continuation lines for a multiline field, and do not end a
2526 <sect id="binarycontrolfiles">
2527 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2530 The <file>DEBIAN/control</file> file contains the most vital
2531 (and version-dependent) information about a binary package.
2535 The fields in this file are:
2537 <list compact="compact">
2538 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2539 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2540 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2541 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2542 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2543 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2544 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2545 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2546 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2547 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2548 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2549 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2554 <sect id="debiansourcecontrolfiles">
2555 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2558 This file contains a series of fields, identified and
2559 separated just like the fields in the control file of
2560 a binary package. The fields are listed below; their
2561 syntax is described above, in <ref id="pkg-controlfields">.
2563 <list compact="compact">
2564 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2565 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2566 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2567 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2568 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2569 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2570 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2571 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2572 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2573 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2574 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2579 The source package control file is generated by
2580 <prgn>dpkg-source</prgn> when it builds the source
2581 archive, from other files in the source package,
2582 described above. When unpacking, it is checked against
2583 the files and directories in the other parts of the
2589 <sect id="debianchangesfiles">
2590 <heading>Debian changes files -- <file>.changes</file></heading>
2593 The .changes files are used by the Debian archive maintenance
2594 software to process updates to packages. They contain one
2595 paragraph which contains information from the
2596 <tt>debian/control</tt> file and other data about the
2597 source package gathered via <tt>debian/changelog</tt>
2598 and <tt>debian/rules</tt>.
2602 The fields in this file are:
2604 <list compact="compact">
2605 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2606 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2607 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2608 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2609 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2610 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2611 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2612 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2613 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2614 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2615 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2616 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2617 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2618 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2623 <sect id="controlfieldslist">
2624 <heading>List of fields</heading>
2626 <sect1 id="f-Source">
2627 <heading><tt>Source</tt></heading>
2630 This field identifies the source package name.
2634 In <file>debian/control</file> or a <file>.dsc</file> file,
2635 this field must contain only the name of the source package.
2639 In a binary package control file or a <file>.changes</file>
2640 file, the source package name may be followed by a version
2641 number in parentheses<footnote>
2642 It is customary to leave a space after the package name
2643 if a version number is specified.
2645 This version number may be omitted (and is, by
2646 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2647 the <tt>Version</tt> field of the binary package in
2648 question. The field itself may be omitted from a binary
2649 package control file when the source package has the same
2650 name and version as the binary package.
2654 Package names (both source and binary,
2655 see <ref id="f-Package">) must consist only of lower case
2656 letters (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus
2657 (<tt>+</tt>) and minus (<tt>-</tt>) signs, and periods
2658 (<tt>.</tt>). They must be at least two characters long and
2659 must start with an alphanumeric character.
2663 <sect1 id="f-Maintainer">
2664 <heading><tt>Maintainer</tt></heading>
2667 The package maintainer's name and email address. The name
2668 should come first, then the email address inside angle
2669 brackets <tt><></tt> (in RFC822 format).
2673 If the maintainer's name contains a full stop then the
2674 whole field will not work directly as an email address due
2675 to a misfeature in the syntax specified in RFC822; a
2676 program using this field as an address must check for this
2677 and correct the problem if necessary (for example by
2678 putting the name in round brackets and moving it to the
2679 end, and bringing the email address forward).
2683 <sect1 id="f-Uploaders">
2684 <heading><tt>Uploaders</tt></heading>
2687 List of the names and email addresses of co-maintainers of
2688 the package, if any. If the package has other maintainers
2689 beside the one named in the
2690 <qref id="f-Maintainer">Maintainer field</qref>, their
2691 names and email addresses should be listed here. The
2692 format is the same as that of the Maintainer tag, and
2693 multiple entries should be comma separated. Currently,
2694 this field is restricted to a single line of data. This
2695 is an optional field.
2698 Any parser that interprets the Uploaders field in
2699 <file>debian/control</file> must permit it to span multiple
2700 lines. Line breaks in an Uploaders field that spans multiple
2701 lines are not significant and the semantics of the field are
2702 the same as if the line breaks had not been present.
2706 <sect1 id="f-Changed-By">
2707 <heading><tt>Changed-By</tt></heading>
2710 The name and email address of the person who changed the
2711 said package. Usually the name of the maintainer.
2712 All the rules for the Maintainer field apply here, too.
2716 <sect1 id="f-Section">
2717 <heading><tt>Section</tt></heading>
2720 This field specifies an application area into which the package
2721 has been classified. See <ref id="subsections">.
2725 When it appears in the <file>debian/control</file> file,
2726 it gives the value for the subfield of the same name in
2727 the <tt>Files</tt> field of the <file>.changes</file> file.
2728 It also gives the default for the same field in the binary
2733 <sect1 id="f-Priority">
2734 <heading><tt>Priority</tt></heading>
2737 This field represents how important it is that the user
2738 have the package installed. See <ref id="priorities">.
2742 When it appears in the <file>debian/control</file> file,
2743 it gives the value for the subfield of the same name in
2744 the <tt>Files</tt> field of the <file>.changes</file> file.
2745 It also gives the default for the same field in the binary
2750 <sect1 id="f-Package">
2751 <heading><tt>Package</tt></heading>
2754 The name of the binary package.
2758 Binary package names must follow the same syntax and
2759 restrictions as source package names. See <ref id="f-Source">
2764 <sect1 id="f-Architecture">
2765 <heading><tt>Architecture</tt></heading>
2768 Depending on context and the control file used, the
2769 <tt>Architecture</tt> field can include the following sets of
2773 A unique single word identifying a Debian machine
2774 architecture as described in <ref id="arch-spec">.
2777 An architecture wildcard identifying a set of Debian
2778 machine architectures, see <ref id="arch-wildcard-spec">.
2779 <tt>any</tt> matches all Debian machine architectures
2780 and is the most frequently used.
2783 <tt>all</tt>, which indicates an
2784 architecture-independent package.
2787 <tt>source</tt>, which indicates a source package.
2793 In the main <file>debian/control</file> file in the source
2794 package, this field may contain the special
2795 value <tt>all</tt>, the special architecture
2796 wildcard <tt>any</tt>, or a list of specific and wildcard
2797 architectures separated by spaces. If <tt>all</tt>
2798 or <tt>any</tt> appears, that value must be the entire
2799 contents of the field. Most packages will use
2800 either <tt>all</tt> or <tt>any</tt>.
2804 Specifying a specific list of architectures indicates that the
2805 source will build an architecture-dependent package only on
2806 architectures included in the list. Specifying a list of
2807 architecture wildcards indicates that the source will build an
2808 architecture-dependent package on only those architectures
2809 that match any of the specified architecture wildcards.
2810 Specifying a list of architectures or architecture wildcards
2811 other than <tt>any</tt> is for the minority of cases where a
2812 program is not portable or is not useful on some
2813 architectures. Where possible, the program should be made
2818 In the source package control file <file>.dsc</file>, this
2819 field may contain either the architecture
2820 wildcard <tt>any</tt> or a list of architectures and
2821 architecture wildcards separated by spaces. If a list is
2822 given, it may include (or consist solely of) the special
2823 value <tt>all</tt>. In other words, in <file>.dsc</file>
2824 files unlike the <file>debian/control</file>, <tt>all</tt> may
2825 occur in combination with specific architectures.
2826 The <tt>Architecture</tt> field in the source package control
2827 file <file>.dsc</file> is generally constructed from
2828 the <tt>Architecture</tt> fields in
2829 the <file>debian/control</file> in the source package.
2833 Specifying <tt>any</tt> indicates that the source package
2834 isn't dependent on any particular architecture and should
2835 compile fine on any one. The produced binary package(s)
2836 will either be specific to whatever the current build
2837 architecture is or will be architecture-independent.
2841 Specifying only <tt>all</tt> indicates that the source package
2842 will only build architecture-independent packages. If this is
2843 the case, <tt>all</tt> must be used rather than <tt>any</tt>;
2844 <tt>any</tt> implies that the source package will build at
2845 least one architecture-dependent package.
2849 Specifying a list of architectures or architecture wildcards
2850 indicates that the source will build an architecture-dependent
2851 package, and will only work correctly on the listed or
2852 matching architectures. If the source package also builds at
2853 least one architecture-independent package, <tt>all</tt> will
2854 also be included in the list.
2858 In a <file>.changes</file> file, the <tt>Architecture</tt>
2859 field lists the architecture(s) of the package(s) currently
2860 being uploaded. This will be a list; if the source for the
2861 package is also being uploaded, the special
2862 entry <tt>source</tt> is also present. <tt>all</tt> will be
2863 present if any architecture-independent packages are being
2864 uploaded. Architecture wildcards such as <tt>any</tt> must
2865 never occur in the <tt>Architecture</tt> field in
2866 the <file>.changes</file> file.
2870 See <ref id="debianrules"> for information on how to get
2871 the architecture for the build process.
2875 <sect1 id="f-Essential">
2876 <heading><tt>Essential</tt></heading>
2879 This is a boolean field which may occur only in the
2880 control file of a binary package or in a per-package fields
2881 paragraph of a main source control data file.
2885 If set to <tt>yes</tt> then the package management system
2886 will refuse to remove the package (upgrading and replacing
2887 it is still possible). The other possible value is <tt>no</tt>,
2888 which is the same as not having the field at all.
2893 <heading>Package interrelationship fields:
2894 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2895 <tt>Recommends</tt>, <tt>Suggests</tt>,
2896 <tt>Breaks</tt>, <tt>Conflicts</tt>,
2897 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2901 These fields describe the package's relationships with
2902 other packages. Their syntax and semantics are described
2903 in <ref id="relationships">.</p>
2906 <sect1 id="f-Standards-Version">
2907 <heading><tt>Standards-Version</tt></heading>
2910 The most recent version of the standards (the policy
2911 manual and associated texts) with which the package
2916 The version number has four components: major and minor
2917 version number and major and minor patch level. When the
2918 standards change in a way that requires every package to
2919 change the major number will be changed. Significant
2920 changes that will require work in many packages will be
2921 signaled by a change to the minor number. The major patch
2922 level will be changed for any change to the meaning of the
2923 standards, however small; the minor patch level will be
2924 changed when only cosmetic, typographical or other edits
2925 are made which neither change the meaning of the document
2926 nor affect the contents of packages.
2930 Thus only the first three components of the policy version
2931 are significant in the <em>Standards-Version</em> control
2932 field, and so either these three components or all four
2933 components may be specified.<footnote>
2934 In the past, people specified the full version number
2935 in the Standards-Version field, for example "2.3.0.0".
2936 Since minor patch-level changes don't introduce new
2937 policy, it was thought it would be better to relax
2938 policy and only require the first 3 components to be
2939 specified, in this example "2.3.0". All four
2940 components may still be used if someone wishes to do so.
2946 <sect1 id="f-Version">
2947 <heading><tt>Version</tt></heading>
2950 The version number of a package. The format is:
2951 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2955 The three components here are:
2957 <tag><var>epoch</var></tag>
2960 This is a single (generally small) unsigned integer. It
2961 may be omitted, in which case zero is assumed. If it is
2962 omitted then the <var>upstream_version</var> may not
2967 It is provided to allow mistakes in the version numbers
2968 of older versions of a package, and also a package's
2969 previous version numbering schemes, to be left behind.
2973 <tag><var>upstream_version</var></tag>
2976 This is the main part of the version number. It is
2977 usually the version number of the original ("upstream")
2978 package from which the <file>.deb</file> file has been made,
2979 if this is applicable. Usually this will be in the same
2980 format as that specified by the upstream author(s);
2981 however, it may need to be reformatted to fit into the
2982 package management system's format and comparison
2987 The comparison behavior of the package management system
2988 with respect to the <var>upstream_version</var> is
2989 described below. The <var>upstream_version</var>
2990 portion of the version number is mandatory.
2994 The <var>upstream_version</var> may contain only
2995 alphanumerics<footnote>
2996 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2998 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2999 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
3000 tilde) and should start with a digit. If there is no
3001 <var>debian_revision</var> then hyphens are not allowed;
3002 if there is no <var>epoch</var> then colons are not
3007 <tag><var>debian_revision</var></tag>
3010 This part of the version number specifies the version of
3011 the Debian package based on the upstream version. It
3012 may contain only alphanumerics and the characters
3013 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
3014 tilde) and is compared in the same way as the
3015 <var>upstream_version</var> is.
3019 It is optional; if it isn't present then the
3020 <var>upstream_version</var> may not contain a hyphen.
3021 This format represents the case where a piece of
3022 software was written specifically to be turned into a
3023 Debian package, and so there is only one "debianisation"
3024 of it and therefore no revision indication is required.
3028 It is conventional to restart the
3029 <var>debian_revision</var> at <tt>1</tt> each time the
3030 <var>upstream_version</var> is increased.
3034 The package management system will break the version
3035 number apart at the last hyphen in the string (if there
3036 is one) to determine the <var>upstream_version</var> and
3037 <var>debian_revision</var>. The absence of a
3038 <var>debian_revision</var> is equivalent to a
3039 <var>debian_revision</var> of <tt>0</tt>.
3046 When comparing two version numbers, first the <var>epoch</var>
3047 of each are compared, then the <var>upstream_version</var> if
3048 <var>epoch</var> is equal, and then <var>debian_revision</var>
3049 if <var>upstream_version</var> is also equal.
3050 <var>epoch</var> is compared numerically. The
3051 <var>upstream_version</var> and <var>debian_revision</var>
3052 parts are compared by the package management system using the
3053 following algorithm:
3057 The strings are compared from left to right.
3061 First the initial part of each string consisting entirely of
3062 non-digit characters is determined. These two parts (one of
3063 which may be empty) are compared lexically. If a difference
3064 is found it is returned. The lexical comparison is a
3065 comparison of ASCII values modified so that all the letters
3066 sort earlier than all the non-letters and so that a tilde
3067 sorts before anything, even the end of a part. For example,
3068 the following parts are in sorted order from earliest to
3069 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
3070 <tt>a</tt>.<footnote>
3071 One common use of <tt>~</tt> is for upstream pre-releases.
3072 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
3073 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
3078 Then the initial part of the remainder of each string which
3079 consists entirely of digit characters is determined. The
3080 numerical values of these two parts are compared, and any
3081 difference found is returned as the result of the comparison.
3082 For these purposes an empty string (which can only occur at
3083 the end of one or both version strings being compared) counts
3088 These two steps (comparing and removing initial non-digit
3089 strings and initial digit strings) are repeated until a
3090 difference is found or both strings are exhausted.
3094 Note that the purpose of epochs is to allow us to leave behind
3095 mistakes in version numbering, and to cope with situations
3096 where the version numbering scheme changes. It is
3097 <em>not</em> intended to cope with version numbers containing
3098 strings of letters which the package management system cannot
3099 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
3100 silly orderings.<footnote>
3101 The author of this manual has heard of a package whose
3102 versions went <tt>1.1</tt>, <tt>1.2</tt>, <tt>1.3</tt>,
3103 <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>, <tt>2</tt> and so
3109 <sect1 id="f-Description">
3110 <heading><tt>Description</tt></heading>
3113 In a source or binary control file, the <tt>Description</tt>
3114 field contains a description of the binary package, consisting
3115 of two parts, the synopsis or the short description, and the
3116 long description. The field's format is as follows:
3121 Description: <single line synopsis>
3122 <extended description over several lines>
3127 The lines in the extended description can have these formats:
3133 Those starting with a single space are part of a paragraph.
3134 Successive lines of this form will be word-wrapped when
3135 displayed. The leading space will usually be stripped off.
3139 Those starting with two or more spaces. These will be
3140 displayed verbatim. If the display cannot be panned
3141 horizontally, the displaying program will line wrap them "hard"
3142 (i.e., without taking account of word breaks). If it can they
3143 will be allowed to trail off to the right. None, one or two
3144 initial spaces may be deleted, but the number of spaces
3145 deleted from each line will be the same (so that you can have
3146 indenting work correctly, for example).
3150 Those containing a single space followed by a single full stop
3151 character. These are rendered as blank lines. This is the
3152 <em>only</em> way to get a blank line<footnote>
3153 Completely empty lines will not be rendered as blank lines.
3154 Instead, they will cause the parser to think you're starting
3155 a whole new record in the control file, and will therefore
3156 likely abort with an error.
3161 Those containing a space, a full stop and some more characters.
3162 These are for future expansion. Do not use them.
3168 Do not use tab characters. Their effect is not predictable.
3172 See <ref id="descriptions"> for further information on this.
3176 In a <file>.changes</file> file, the <tt>Description</tt>
3177 field contains a summary of the descriptions for the packages
3178 being uploaded. For this case, the first line of the field
3179 value (the part on the same line as <tt>Description:</tt>) is
3180 always empty. The content of the field is expressed as
3181 continuation lines, one line per package. Each line is
3182 indented by one space and contains the name of a binary
3183 package, a space, a hyphen (<tt>-</tt>), a space, and the
3184 short description line from that package.
3188 <sect1 id="f-Distribution">
3189 <heading><tt>Distribution</tt></heading>
3192 In a <file>.changes</file> file or parsed changelog output
3193 this contains the (space-separated) name(s) of the
3194 distribution(s) where this version of the package should
3195 be installed. Valid distributions are determined by the
3196 archive maintainers.<footnote>
3197 Example distribution names in the Debian archive used in
3198 <file>.changes</file> files are:
3199 <taglist compact="compact">
3200 <tag><em>unstable</em></tag>
3202 This distribution value refers to the
3203 <em>developmental</em> part of the Debian distribution
3204 tree. Most new packages, new upstream versions of
3205 packages and bug fixes go into the <em>unstable</em>
3209 <tag><em>experimental</em></tag>
3211 The packages with this distribution value are deemed
3212 by their maintainers to be high risk. Oftentimes they
3213 represent early beta or developmental packages from
3214 various sources that the maintainers want people to
3215 try, but are not ready to be a part of the other parts
3216 of the Debian distribution tree.
3221 Others are used for updating stable releases or for
3222 security uploads. More information is available in the
3223 Debian Developer's Reference, section "The Debian
3227 The Debian archive software only supports listing a single
3228 distribution. Migration of packages to other distributions is
3229 handled outside of the upload process.
3234 <heading><tt>Date</tt></heading>
3237 This field includes the date the package was built or last
3238 edited. It must be in the same format as the <var>date</var>
3239 in a <file>debian/changelog</file> entry.
3243 The value of this field is usually extracted from the
3244 <file>debian/changelog</file> file - see
3245 <ref id="dpkgchangelog">).
3249 <sect1 id="f-Format">
3250 <heading><tt>Format</tt></heading>
3253 This field specifies a format revision for the file.
3254 The most current format described in the Policy Manual
3255 is version <strong>1.5</strong>. The syntax of the
3256 format value is the same as that of a package version
3257 number except that no epoch or Debian revision is allowed
3258 - see <ref id="f-Version">.
3262 <sect1 id="f-Urgency">
3263 <heading><tt>Urgency</tt></heading>
3266 This is a description of how important it is to upgrade to
3267 this version from previous ones. It consists of a single
3268 keyword taking one of the values <tt>low</tt>,
3269 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3270 <tt>critical</tt><footnote>
3271 Other urgency values are supported with configuration
3272 changes in the archive software but are not used in Debian.
3273 The urgency affects how quickly a package will be considered
3274 for inclusion into the <tt>testing</tt> distribution and
3275 gives an indication of the importance of any fixes included
3276 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3277 treated as synonymous.
3278 </footnote> (not case-sensitive) followed by an optional
3279 commentary (separated by a space) which is usually in
3280 parentheses. For example:
3283 Urgency: low (HIGH for users of diversions)
3289 The value of this field is usually extracted from the
3290 <file>debian/changelog</file> file - see
3291 <ref id="dpkgchangelog">.
3295 <sect1 id="f-Changes">
3296 <heading><tt>Changes</tt></heading>
3299 This field contains the human-readable changes data, describing
3300 the differences between the last version and the current one.
3304 The first line of the field value (the part on the same line
3305 as <tt>Changes:</tt>) is always empty. The content of the
3306 field is expressed as continuation lines, with each line
3307 indented by at least one space. Blank lines must be
3308 represented by a line consisting only of a space and a full
3313 The value of this field is usually extracted from the
3314 <file>debian/changelog</file> file - see
3315 <ref id="dpkgchangelog">).
3319 Each version's change information should be preceded by a
3320 "title" line giving at least the version, distribution(s)
3321 and urgency, in a human-readable way.
3325 If data from several versions is being returned the entry
3326 for the most recent version should be returned first, and
3327 entries should be separated by the representation of a
3328 blank line (the "title" line may also be followed by the
3329 representation of a blank line).
3333 <sect1 id="f-Binary">
3334 <heading><tt>Binary</tt></heading>
3337 This field is a list of binary packages. Its syntax and
3338 meaning varies depending on the control file in which it
3343 When it appears in the <file>.dsc</file> file, it lists binary
3344 packages which a source package can produce, separated by
3346 A space after each comma is conventional.
3347 </footnote>. It may span multiple lines. The source package
3348 does not necessarily produce all of these binary packages for
3349 every architecture. The source control file doesn't contain
3350 details of which architectures are appropriate for which of
3351 the binary packages.
3355 When it appears in a <file>.changes</file> file, it lists the
3356 names of the binary packages being uploaded, separated by
3357 whitespace (not commas). It may span multiple lines.
3361 <sect1 id="f-Installed-Size">
3362 <heading><tt>Installed-Size</tt></heading>
3365 This field appears in the control files of binary packages,
3366 and in the <file>Packages</file> files. It gives an estimate
3367 of the total amount of disk space required to install the
3368 named package. Actual installed size may vary based on block
3369 size, file system properties, or actions taken by package
3374 The disk space is given as the integer value of the estimated
3375 installed size in bytes, divided by 1024 and rounded up.
3379 <sect1 id="f-Files">
3380 <heading><tt>Files</tt></heading>
3383 This field contains a list of files with information about
3384 each one. The exact information and syntax varies with
3389 In all cases, Files is a multiline field. The first line of
3390 the field value (the part on the same line as <tt>Files:</tt>)
3391 is always empty. The content of the field is expressed as
3392 continuation lines, one line per file. Each line must be
3393 indented by one space and contain a number of sub-fields,
3394 separated by spaces, as described below.
3398 In the <file>.dsc</file> file, each line contains the MD5
3399 checksum, size and filename of the tar file and (if
3400 applicable) diff file which make up the remainder of the
3401 source package<footnote>
3402 That is, the parts which are not the <tt>.dsc</tt>.
3403 </footnote>. For example:
3406 c6f698f19f2a2aa07dbb9bbda90a2754 571925 example_1.2.orig.tar.gz
3407 938512f08422f3509ff36f125f5873ba 6220 example_1.2-1.diff.gz
3409 The exact forms of the filenames are described
3410 in <ref id="pkg-sourcearchives">.
3414 In the <file>.changes</file> file this contains one line per
3415 file being uploaded. Each line contains the MD5 checksum,
3416 size, section and priority and the filename. For example:
3419 4c31ab7bfc40d3cf49d7811987390357 1428 text extra example_1.2-1.dsc
3420 c6f698f19f2a2aa07dbb9bbda90a2754 571925 text extra example_1.2.orig.tar.gz
3421 938512f08422f3509ff36f125f5873ba 6220 text extra example_1.2-1.diff.gz
3422 7c98fe853b3bbb47a00e5cd129b6cb56 703542 text extra example_1.2-1_i386.deb
3424 The <qref id="f-Section">section</qref>
3425 and <qref id="f-Priority">priority</qref> are the values of
3426 the corresponding fields in the main source control file. If
3427 no section or priority is specified then <tt>-</tt> should be
3428 used, though section and priority values must be specified for
3429 new packages to be installed properly.
3433 The special value <tt>byhand</tt> for the section in a
3434 <tt>.changes</tt> file indicates that the file in question
3435 is not an ordinary package file and must by installed by
3436 hand by the distribution maintainers. If the section is
3437 <tt>byhand</tt> the priority should be <tt>-</tt>.
3441 If a new Debian revision of a package is being shipped and
3442 no new original source archive is being distributed the
3443 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3444 entry for the original source archive
3445 <file><var>package</var>_<var>upstream-version</var>.orig.tar.gz</file>,
3446 but the <file>.changes</file> file should leave it out. In
3447 this case the original source archive on the distribution
3448 site must match exactly, byte-for-byte, the original
3449 source archive which was used to generate the
3450 <file>.dsc</file> file and diff which are being uploaded.</p>
3453 <sect1 id="f-Closes">
3454 <heading><tt>Closes</tt></heading>
3457 A space-separated list of bug report numbers that the upload
3458 governed by the .changes file closes.
3462 <sect1 id="f-Homepage">
3463 <heading><tt>Homepage</tt></heading>
3466 The URL of the web site for this package, preferably (when
3467 applicable) the site from which the original source can be
3468 obtained and any additional upstream documentation or
3469 information may be found. The content of this field is a
3470 simple URL without any surrounding characters such as
3478 <heading>User-defined fields</heading>
3481 Additional user-defined fields may be added to the
3482 source package control file. Such fields will be
3483 ignored, and not copied to (for example) binary or
3484 source package control files or upload control files.
3488 If you wish to add additional unsupported fields to
3489 these output files you should use the mechanism
3494 Fields in the main source control information file with
3495 names starting <tt>X</tt>, followed by one or more of
3496 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3497 be copied to the output files. Only the part of the
3498 field name after the hyphen will be used in the output
3499 file. Where the letter <tt>B</tt> is used the field
3500 will appear in binary package control files, where the
3501 letter <tt>S</tt> is used in source package control
3502 files and where <tt>C</tt> is used in upload control
3503 (<tt>.changes</tt>) files.
3507 For example, if the main source information control file
3510 XBS-Comment: I stand between the candle and the star.
3512 then the binary and source package control files will contain the
3515 Comment: I stand between the candle and the star.
3524 <chapt id="maintainerscripts">
3525 <heading>Package maintainer scripts and installation procedure</heading>
3528 <heading>Introduction to package maintainer scripts</heading>
3531 It is possible to supply scripts as part of a package which
3532 the package management system will run for you when your
3533 package is installed, upgraded or removed.
3537 These scripts are the files <prgn>preinst</prgn>,
3538 <prgn>postinst</prgn>, <prgn>prerm</prgn> and
3539 <prgn>postrm</prgn> in the control area of the package.
3540 They must be proper executable files; if they are scripts
3541 (which is recommended), they must start with the usual
3542 <tt>#!</tt> convention. They should be readable and
3543 executable by anyone, and must not be world-writable.
3547 The package management system looks at the exit status from
3548 these scripts. It is important that they exit with a
3549 non-zero status if there is an error, so that the package
3550 management system can stop its processing. For shell
3551 scripts this means that you <em>almost always</em> need to
3552 use <tt>set -e</tt> (this is usually true when writing shell
3553 scripts, in fact). It is also important, of course, that
3554 they exit with a zero status if everything went well.
3558 Additionally, packages interacting with users using
3559 <tt>debconf</tt> in the <prgn>postinst</prgn> script should
3560 install a <prgn>config</prgn> script in the control area,
3561 see <ref id="maintscriptprompt"> for details.
3565 When a package is upgraded a combination of the scripts from
3566 the old and new packages is called during the upgrade
3567 procedure. If your scripts are going to be at all
3568 complicated you need to be aware of this, and may need to
3569 check the arguments to your scripts.
3573 Broadly speaking the <prgn>preinst</prgn> is called before
3574 (a particular version of) a package is installed, and the
3575 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3576 before (a version of) a package is removed and the
3577 <prgn>postrm</prgn> afterwards.
3581 Programs called from maintainer scripts should not normally
3582 have a path prepended to them. Before installation is
3583 started, the package management system checks to see if the
3584 programs <prgn>ldconfig</prgn>,
3585 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3586 and <prgn>update-rc.d</prgn> can be found via the
3587 <tt>PATH</tt> environment variable. Those programs, and any
3588 other program that one would expect to be in the
3589 <tt>PATH</tt>, should thus be invoked without an absolute
3590 pathname. Maintainer scripts should also not reset the
3591 <tt>PATH</tt>, though they might choose to modify it by
3592 prepending or appending package-specific directories. These
3593 considerations really apply to all shell scripts.</p>
3596 <sect id="idempotency">
3597 <heading>Maintainer scripts idempotency</heading>
3600 It is necessary for the error recovery procedures that the
3601 scripts be idempotent. This means that if it is run
3602 successfully, and then it is called again, it doesn't bomb
3603 out or cause any harm, but just ensures that everything is
3604 the way it ought to be. If the first call failed, or
3605 aborted half way through for some reason, the second call
3606 should merely do the things that were left undone the first
3607 time, if any, and exit with a success status if everything
3609 This is so that if an error occurs, the user interrupts
3610 <prgn>dpkg</prgn> or some other unforeseen circumstance
3611 happens you don't leave the user with a badly-broken
3612 package when <prgn>dpkg</prgn> attempts to repeat the
3618 <sect id="controllingterminal">
3619 <heading>Controlling terminal for maintainer scripts</heading>
3622 Maintainer scripts are not guaranteed to run with a controlling
3623 terminal and may not be able to interact with the user. They
3624 must be able to fall back to noninteractive behavior if no
3625 controlling terminal is available. Maintainer scripts that
3626 prompt via a program conforming to the Debian Configuration
3627 Management Specification (see <ref id="maintscriptprompt">) may
3628 assume that program will handle falling back to noninteractive
3633 For high-priority prompts without a reasonable default answer,
3634 maintainer scripts may abort if there is no controlling
3635 terminal. However, this situation should be avoided if at all
3636 possible, since it prevents automated or unattended installs.
3637 In most cases, users will consider this to be a bug in the
3642 <sect id="exitstatus">
3643 <heading>Exit status</heading>
3646 Each script must return a zero exit status for
3647 success, or a nonzero one for failure, since the package
3648 management system looks for the exit status of these scripts
3649 and determines what action to take next based on that datum.
3653 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3658 <list compact="compact">
3660 <var>new-preinst</var> <tt>install</tt>
3663 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3666 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3669 <var>old-preinst</var> <tt>abort-upgrade</tt>
3670 <var>new-version</var>
3675 <list compact="compact">
3677 <var>postinst</var> <tt>configure</tt>
3678 <var>most-recently-configured-version</var>
3681 <var>old-postinst</var> <tt>abort-upgrade</tt>
3682 <var>new-version</var>
3685 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3686 <tt>in-favour</tt> <var>package</var>
3687 <var>new-version</var>
3690 <var>postinst</var> <tt>abort-remove</tt>
3693 <var>deconfigured's-postinst</var>
3694 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3695 <var>failed-install-package</var> <var>version</var>
3696 [<tt>removing</tt> <var>conflicting-package</var>
3702 <list compact="compact">
3704 <var>prerm</var> <tt>remove</tt>
3707 <var>old-prerm</var> <tt>upgrade</tt>
3708 <var>new-version</var>
3711 <var>new-prerm</var> <tt>failed-upgrade</tt>
3712 <var>old-version</var>
3715 <var>conflictor's-prerm</var> <tt>remove</tt>
3716 <tt>in-favour</tt> <var>package</var>
3717 <var>new-version</var>
3720 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3721 <tt>in-favour</tt> <var>package-being-installed</var>
3722 <var>version</var> [<tt>removing</tt>
3723 <var>conflicting-package</var>
3729 <list compact="compact">
3731 <var>postrm</var> <tt>remove</tt>
3734 <var>postrm</var> <tt>purge</tt>
3737 <var>old-postrm</var> <tt>upgrade</tt>
3738 <var>new-version</var>
3741 <var>new-postrm</var> <tt>failed-upgrade</tt>
3742 <var>old-version</var>
3745 <var>new-postrm</var> <tt>abort-install</tt>
3748 <var>new-postrm</var> <tt>abort-install</tt>
3749 <var>old-version</var>
3752 <var>new-postrm</var> <tt>abort-upgrade</tt>
3753 <var>old-version</var>
3756 <var>disappearer's-postrm</var> <tt>disappear</tt>
3757 <var>overwriter</var>
3758 <var>overwriter-version</var>
3764 <sect id="unpackphase">
3765 <heading>Details of unpack phase of installation or upgrade</heading>
3768 The procedure on installation/upgrade/overwrite/disappear
3769 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3770 stage of <tt>dpkg --install</tt>) is as follows. In each
3771 case, if a major error occurs (unless listed below) the
3772 actions are, in general, run backwards - this means that the
3773 maintainer scripts are run with different arguments in
3774 reverse order. These are the "error unwind" calls listed
3781 If a version of the package is already installed, call
3782 <example compact="compact">
3783 <var>old-prerm</var> upgrade <var>new-version</var>
3787 If the script runs but exits with a non-zero
3788 exit status, <prgn>dpkg</prgn> will attempt:
3789 <example compact="compact">
3790 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3792 If this works, the upgrade continues. If this
3793 does not work, the error unwind:
3794 <example compact="compact">
3795 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3797 If this works, then the old-version is
3798 "Installed", if not, the old version is in a
3799 "Half-Configured" state.
3805 If a "conflicting" package is being removed at the same time,
3806 or if any package will be broken (due to <tt>Breaks</tt>):
3809 If <tt>--auto-deconfigure</tt> is
3810 specified, call, for each package to be deconfigured
3811 due to <tt>Breaks</tt>:
3812 <example compact="compact">
3813 <var>deconfigured's-prerm</var> deconfigure \
3814 in-favour <var>package-being-installed</var> <var>version</var>
3817 <example compact="compact">
3818 <var>deconfigured's-postinst</var> abort-deconfigure \
3819 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3821 The deconfigured packages are marked as
3822 requiring configuration, so that if
3823 <tt>--install</tt> is used they will be
3824 configured again if possible.
3827 If any packages depended on a conflicting
3828 package being removed and <tt>--auto-deconfigure</tt> is
3829 specified, call, for each such package:
3830 <example compact="compact">
3831 <var>deconfigured's-prerm</var> deconfigure \
3832 in-favour <var>package-being-installed</var> <var>version</var> \
3833 removing <var>conflicting-package</var> <var>version</var>
3836 <example compact="compact">
3837 <var>deconfigured's-postinst</var> abort-deconfigure \
3838 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3839 removing <var>conflicting-package</var> <var>version</var>
3841 The deconfigured packages are marked as
3842 requiring configuration, so that if
3843 <tt>--install</tt> is used they will be
3844 configured again if possible.
3847 To prepare for removal of each conflicting package, call:
3848 <example compact="compact">
3849 <var>conflictor's-prerm</var> remove \
3850 in-favour <var>package</var> <var>new-version</var>
3853 <example compact="compact">
3854 <var>conflictor's-postinst</var> abort-remove \
3855 in-favour <var>package</var> <var>new-version</var>
3864 If the package is being upgraded, call:
3865 <example compact="compact">
3866 <var>new-preinst</var> upgrade <var>old-version</var>
3868 If this fails, we call:
3870 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3877 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3879 is called. If this works, then the old version
3880 is in an "Installed" state, or else it is left
3881 in an "Unpacked" state.
3886 If it fails, then the old version is left
3887 in an "Half-Installed" state.
3894 Otherwise, if the package had some configuration
3895 files from a previous version installed (i.e., it
3896 is in the "configuration files only" state):
3897 <example compact="compact">
3898 <var>new-preinst</var> install <var>old-version</var>
3902 <var>new-postrm</var> abort-install <var>old-version</var>
3904 If this fails, the package is left in a
3905 "Half-Installed" state, which requires a
3906 reinstall. If it works, the packages is left in
3907 a "Config-Files" state.
3910 Otherwise (i.e., the package was completely purged):
3911 <example compact="compact">
3912 <var>new-preinst</var> install
3915 <example compact="compact">
3916 <var>new-postrm</var> abort-install
3918 If the error-unwind fails, the package is in a
3919 "Half-Installed" phase, and requires a
3920 reinstall. If the error unwind works, the
3921 package is in a not installed state.
3928 The new package's files are unpacked, overwriting any
3929 that may be on the system already, for example any
3930 from the old version of the same package or from
3931 another package. Backups of the old files are kept
3932 temporarily, and if anything goes wrong the package
3933 management system will attempt to put them back as
3934 part of the error unwind.
3938 It is an error for a package to contain files which
3939 are on the system in another package, unless
3940 <tt>Replaces</tt> is used (see <ref id="replaces">).
3942 The following paragraph is not currently the case:
3943 Currently the <tt>- - force-overwrite</tt> flag is
3944 enabled, downgrading it to a warning, but this may not
3950 It is a more serious error for a package to contain a
3951 plain file or other kind of non-directory where another
3952 package has a directory (again, unless
3953 <tt>Replaces</tt> is used). This error can be
3954 overridden if desired using
3955 <tt>--force-overwrite-dir</tt>, but this is not
3960 Packages which overwrite each other's files produce
3961 behavior which, though deterministic, is hard for the
3962 system administrator to understand. It can easily
3963 lead to "missing" programs if, for example, a package
3964 is installed which overwrites a file from another
3965 package, and is then removed again.<footnote>
3966 Part of the problem is due to what is arguably a
3967 bug in <prgn>dpkg</prgn>.
3972 A directory will never be replaced by a symbolic link
3973 to a directory or vice versa; instead, the existing
3974 state (symlink or not) will be left alone and
3975 <prgn>dpkg</prgn> will follow the symlink if there is
3984 If the package is being upgraded, call
3985 <example compact="compact">
3986 <var>old-postrm</var> upgrade <var>new-version</var>
3990 If this fails, <prgn>dpkg</prgn> will attempt:
3991 <example compact="compact">
3992 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3994 If this works, installation continues. If not,
3996 <example compact="compact">
3997 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3999 If this fails, the old version is left in a
4000 "Half-Installed" state. If it works, dpkg now
4002 <example compact="compact">
4003 <var>new-postrm</var> abort-upgrade <var>old-version</var>
4005 If this fails, the old version is left in a
4006 "Half-Installed" state. If it works, dpkg now
4008 <example compact="compact">
4009 <var>old-postinst</var> abort-upgrade <var>new-version</var>
4011 If this fails, the old version is in an
4018 This is the point of no return - if
4019 <prgn>dpkg</prgn> gets this far, it won't back off
4020 past this point if an error occurs. This will
4021 leave the package in a fairly bad state, which
4022 will require a successful re-installation to clear
4023 up, but it's when <prgn>dpkg</prgn> starts doing
4024 things that are irreversible.
4029 Any files which were in the old version of the package
4030 but not in the new are removed.
4034 The new file list replaces the old.
4038 The new maintainer scripts replace the old.
4042 Any packages all of whose files have been overwritten
4043 during the installation, and which aren't required for
4044 dependencies, are considered to have been removed.
4045 For each such package
4048 <prgn>dpkg</prgn> calls:
4049 <example compact="compact">
4050 <var>disappearer's-postrm</var> disappear \
4051 <var>overwriter</var> <var>overwriter-version</var>
4055 The package's maintainer scripts are removed.
4058 It is noted in the status database as being in a
4059 sane state, namely not installed (any conffiles
4060 it may have are ignored, rather than being
4061 removed by <prgn>dpkg</prgn>). Note that
4062 disappearing packages do not have their prerm
4063 called, because <prgn>dpkg</prgn> doesn't know
4064 in advance that the package is going to
4071 Any files in the package we're unpacking that are also
4072 listed in the file lists of other packages are removed
4073 from those lists. (This will lobotomize the file list
4074 of the "conflicting" package if there is one.)
4078 The backup files made during installation, above, are
4084 The new package's status is now sane, and recorded as
4089 Here is another point of no return - if the
4090 conflicting package's removal fails we do not unwind
4091 the rest of the installation; the conflicting package
4092 is left in a half-removed limbo.
4097 If there was a conflicting package we go and do the
4098 removal actions (described below), starting with the
4099 removal of the conflicting package's files (any that
4100 are also in the package being installed have already
4101 been removed from the conflicting package's file list,
4102 and so do not get removed now).
4108 <sect id="configdetails"><heading>Details of configuration</heading>
4111 When we configure a package (this happens with <tt>dpkg
4112 --install</tt> and <tt>dpkg --configure</tt>), we first
4113 update any <tt>conffile</tt>s and then call:
4114 <example compact="compact">
4115 <var>postinst</var> configure <var>most-recently-configured-version</var>
4120 No attempt is made to unwind after errors during
4121 configuration. If the configuration fails, the package is in
4122 a "Failed Config" state, and an error message is generated.
4126 If there is no most recently configured version
4127 <prgn>dpkg</prgn> will pass a null argument.
4130 Historical note: Truly ancient (pre-1997) versions of
4131 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4132 (including the angle brackets) in this case. Even older
4133 ones did not pass a second argument at all, under any
4134 circumstance. Note that upgrades using such an old dpkg
4135 version are unlikely to work for other reasons, even if
4136 this old argument behavior is handled by your postinst script.
4142 <sect id="removedetails"><heading>Details of removal and/or
4143 configuration purging</heading>
4149 <example compact="compact">
4150 <var>prerm</var> remove
4154 If prerm fails during replacement due to conflict
4156 <var>conflictor's-postinst</var> abort-remove \
4157 in-favour <var>package</var> <var>new-version</var>
4161 <var>postinst</var> abort-remove
4165 If this fails, the package is in a "Half-Configured"
4166 state, or else it remains "Installed".
4170 The package's files are removed (except <tt>conffile</tt>s).
4173 <example compact="compact">
4174 <var>postrm</var> remove
4178 If it fails, there's no error unwind, and the package is in
4179 an "Half-Installed" state.
4184 All the maintainer scripts except the <prgn>postrm</prgn>
4189 If we aren't purging the package we stop here. Note
4190 that packages which have no <prgn>postrm</prgn> and no
4191 <tt>conffile</tt>s are automatically purged when
4192 removed, as there is no difference except for the
4193 <prgn>dpkg</prgn> status.
4197 The <tt>conffile</tt>s and any backup files
4198 (<tt>~</tt>-files, <tt>#*#</tt> files,
4199 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4204 <example compact="compact">
4205 <var>postrm</var> purge
4209 If this fails, the package remains in a "Config-Files"
4214 The package's file list is removed.
4223 <chapt id="relationships">
4224 <heading>Declaring relationships between packages</heading>
4226 <sect id="depsyntax">
4227 <heading>Syntax of relationship fields</heading>
4230 These fields all have a uniform syntax. They are a list of
4231 package names separated by commas.
4235 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4236 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4237 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4238 control file fields of the package, which declare
4239 dependencies on other packages, the package names listed may
4240 also include lists of alternative package names, separated
4241 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4242 if any one of the alternative packages is installed, that
4243 part of the dependency is considered to be satisfied.
4247 All of the fields except for <tt>Provides</tt> may restrict
4248 their applicability to particular versions of each named
4249 package. This is done in parentheses after each individual
4250 package name; the parentheses should contain a relation from
4251 the list below followed by a version number, in the format
4252 described in <ref id="f-Version">.
4256 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4257 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4258 strictly earlier, earlier or equal, exactly equal, later or
4259 equal and strictly later, respectively. The deprecated
4260 forms <tt><</tt> and <tt>></tt> were used to mean
4261 earlier/later or equal, rather than strictly earlier/later,
4262 so they should not appear in new packages (though
4263 <prgn>dpkg</prgn> still supports them).
4267 Whitespace may appear at any point in the version
4268 specification subject to the rules in <ref
4269 id="controlsyntax">, and must appear where it's necessary to
4270 disambiguate; it is not otherwise significant. All of the
4271 relationship fields may span multiple lines. For
4272 consistency and in case of future changes to
4273 <prgn>dpkg</prgn> it is recommended that a single space be
4274 used after a version relationship and before a version
4275 number; it is also conventional to put a single space after
4276 each comma, on either side of each vertical bar, and before
4277 each open parenthesis. When wrapping a relationship field, it
4278 is conventional to do so after a comma and before the space
4279 following that comma.
4283 For example, a list of dependencies might appear as:
4284 <example compact="compact">
4287 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4292 All fields that specify build-time relationships
4293 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4294 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
4295 may be restricted to a certain set of architectures. This
4296 is indicated in brackets after each individual package name and
4297 the optional version specification. The brackets enclose a
4298 list of Debian architecture names separated by whitespace.
4299 Exclamation marks may be prepended to each of the names.
4300 (It is not permitted for some names to be prepended with
4301 exclamation marks while others aren't.) If the current Debian
4302 host architecture is not in this list and there are no
4303 exclamation marks in the list, or it is in the list with a
4304 prepended exclamation mark, the package name and the
4305 associated version specification are ignored completely for
4306 the purposes of defining the relationships.
4311 <example compact="compact">
4313 Build-Depends-Indep: texinfo
4314 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4315 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4317 requires <tt>kernel-headers-2.2.10</tt> on all architectures
4318 other than hurd-i386 and requires <tt>hurd-dev</tt> and
4319 <tt>gnumach-dev</tt> only on hurd-i386.
4323 If the architecture-restricted dependency is part of a set of
4324 alternatives using <tt>|</tt>, that alternative is ignored
4325 completely on architectures that do not match the restriction.
4327 <example compact="compact">
4328 Build-Depends: foo [!i386] | bar [!amd64]
4330 is equivalent to <tt>bar</tt> on the i386 architecture, to
4331 <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
4332 bar</tt> on all other architectures.
4336 All fields that specify build-time relationships may also be
4337 restricted to a certain set of architectures using architecture
4338 wildcards. The syntax for declaring such restrictions is the
4339 same as declaring restrictions using a certain set of
4340 architectures without architecture wildcards. For example:
4341 <example compact="compact">
4342 Build-Depends: foo [linux-any], bar [any-i386], baz [!linux-any]
4344 is equivalent to <tt>foo</tt> on architectures using the Linux
4345 kernel and any cpu, <tt>bar</tt> on architectures using any
4346 kernel and an i386 cpu, and <tt>baz</tt> on any architecture
4347 using a kernel other than Linux.
4351 Note that the binary package relationship fields such as
4352 <tt>Depends</tt> appear in one of the binary package
4353 sections of the control file, whereas the build-time
4354 relationships such as <tt>Build-Depends</tt> appear in the
4355 source package section of the control file (which is the
4360 <sect id="binarydeps">
4361 <heading>Binary Dependencies - <tt>Depends</tt>,
4362 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4363 <tt>Pre-Depends</tt>
4367 Packages can declare in their control file that they have
4368 certain relationships to other packages - for example, that
4369 they may not be installed at the same time as certain other
4370 packages, and/or that they depend on the presence of others.
4374 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4375 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4376 <tt>Breaks</tt> and <tt>Conflicts</tt> control file fields.
4377 <tt>Breaks</tt> is described in <ref id="breaks">, and
4378 <tt>Conflicts</tt> is described in <ref id="conflicts">. The
4379 rest are described below.
4383 These seven fields are used to declare a dependency
4384 relationship by one package on another. Except for
4385 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4386 depending (binary) package's control file.
4387 (<tt>Enhances</tt> appears in the recommending package's
4388 control file, and <tt>Breaks</tt> appears in the version of
4389 depended-on package which causes the named package to
4394 A <tt>Depends</tt> field takes effect <em>only</em> when a
4395 package is to be configured. It does not prevent a package
4396 being on the system in an unconfigured state while its
4397 dependencies are unsatisfied, and it is possible to replace
4398 a package whose dependencies are satisfied and which is
4399 properly installed with a different version whose
4400 dependencies are not and cannot be satisfied; when this is
4401 done the depending package will be left unconfigured (since
4402 attempts to configure it will give errors) and will not
4403 function properly. If it is necessary, a
4404 <tt>Pre-Depends</tt> field can be used, which has a partial
4405 effect even when a package is being unpacked, as explained
4406 in detail below. (The other three dependency fields,
4407 <tt>Recommends</tt>, <tt>Suggests</tt> and
4408 <tt>Enhances</tt>, are only used by the various front-ends
4409 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4410 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4414 For this reason packages in an installation run are usually
4415 all unpacked first and all configured later; this gives
4416 later versions of packages with dependencies on later
4417 versions of other packages the opportunity to have their
4418 dependencies satisfied.
4422 In case of circular dependencies, since installation or
4423 removal order honoring the dependency order can't be
4424 established, dependency loops are broken at some point
4425 (based on rules below), and some packages may not be able to
4426 rely on their dependencies being present when being
4427 installed or removed, depending on which side of the break
4428 of the circular dependency loop they happen to be on. If one
4429 of the packages in the loop has no postinst script, then the
4430 cycle will be broken at that package, so as to ensure that
4431 all postinst scripts run with the dependencies properly
4432 configured if this is possible. Otherwise the breaking point
4437 The <tt>Depends</tt> field thus allows package maintainers
4438 to impose an order in which packages should be configured.
4442 The meaning of the five dependency fields is as follows:
4444 <tag><tt>Depends</tt></tag>
4447 This declares an absolute dependency. A package will
4448 not be configured unless all of the packages listed in
4449 its <tt>Depends</tt> field have been correctly
4454 The <tt>Depends</tt> field should be used if the
4455 depended-on package is required for the depending
4456 package to provide a significant amount of
4461 The <tt>Depends</tt> field should also be used if the
4462 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4463 <prgn>postrm</prgn> scripts require the package to be
4464 present in order to run. Note, however, that the
4465 <prgn>postrm</prgn> cannot rely on any non-essential
4466 packages to be present during the <tt>purge</tt>
4470 <tag><tt>Recommends</tt></tag>
4473 This declares a strong, but not absolute, dependency.
4477 The <tt>Recommends</tt> field should list packages
4478 that would be found together with this one in all but
4479 unusual installations.
4483 <tag><tt>Suggests</tt></tag>
4485 This is used to declare that one package may be more
4486 useful with one or more others. Using this field
4487 tells the packaging system and the user that the
4488 listed packages are related to this one and can
4489 perhaps enhance its usefulness, but that installing
4490 this one without them is perfectly reasonable.
4493 <tag><tt>Enhances</tt></tag>
4495 This field is similar to Suggests but works in the
4496 opposite direction. It is used to declare that a
4497 package can enhance the functionality of another
4501 <tag><tt>Pre-Depends</tt></tag>
4504 This field is like <tt>Depends</tt>, except that it
4505 also forces <prgn>dpkg</prgn> to complete installation
4506 of the packages named before even starting the
4507 installation of the package which declares the
4508 pre-dependency, as follows:
4512 When a package declaring a pre-dependency is about to
4513 be <em>unpacked</em> the pre-dependency can be
4514 satisfied if the depended-on package is either fully
4515 configured, <em>or even if</em> the depended-on
4516 package(s) are only unpacked or in the "Half-Configured"
4517 state, provided that they have been configured
4518 correctly at some point in the past (and not removed
4519 or partially removed since). In this case, both the
4520 previously-configured and currently unpacked or
4521 "Half-Configured" versions must satisfy any version
4522 clause in the <tt>Pre-Depends</tt> field.
4526 When the package declaring a pre-dependency is about
4527 to be <em>configured</em>, the pre-dependency will be
4528 treated as a normal <tt>Depends</tt>, that is, it will
4529 be considered satisfied only if the depended-on
4530 package has been correctly configured.
4534 <tt>Pre-Depends</tt> should be used sparingly,
4535 preferably only by packages whose premature upgrade or
4536 installation would hamper the ability of the system to
4537 continue with any upgrade that might be in progress.
4541 <tt>Pre-Depends</tt> are also required if the
4542 <prgn>preinst</prgn> script depends on the named
4543 package. It is best to avoid this situation if
4551 When selecting which level of dependency to use you should
4552 consider how important the depended-on package is to the
4553 functionality of the one declaring the dependency. Some
4554 packages are composed of components of varying degrees of
4555 importance. Such a package should list using
4556 <tt>Depends</tt> the package(s) which are required by the
4557 more important components. The other components'
4558 requirements may be mentioned as Suggestions or
4559 Recommendations, as appropriate to the components' relative
4565 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4568 When one binary package declares that it breaks another,
4569 <prgn>dpkg</prgn> will refuse to allow the package which
4570 declares <tt>Breaks</tt> be installed unless the broken
4571 package is deconfigured first, and it will refuse to
4572 allow the broken package to be reconfigured.
4576 A package will not be regarded as causing breakage merely
4577 because its configuration files are still installed; it must
4578 be at least "Half-Installed".
4582 A special exception is made for packages which declare that
4583 they break their own package name or a virtual package which
4584 they provide (see below): this does not count as a real
4589 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4590 version clause; such a <tt>Breaks</tt> is introduced in the
4591 version of an (implicit or explicit) dependency which
4592 violates an assumption or reveals a bug in earlier versions
4593 of the broken package. This use of <tt>Breaks</tt> will
4594 inform higher-level package management tools that broken
4595 package must be upgraded before the new one.
4599 If the breaking package also overwrites some files from the
4600 older package, it should use <tt>Replaces</tt> (not
4601 <tt>Conflicts</tt>) to ensure this goes smoothly.
4605 <sect id="conflicts">
4606 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4609 When one binary package declares a conflict with another
4610 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4611 refuse to allow them to be installed on the system at the
4616 If one package is to be installed, the other must be removed
4617 first - if the package being installed is marked as
4618 replacing (see <ref id="replaces">) the one on the system,
4619 or the one on the system is marked as deselected, or both
4620 packages are marked <tt>Essential</tt>, then
4621 <prgn>dpkg</prgn> will automatically remove the package
4622 which is causing the conflict, otherwise it will halt the
4623 installation of the new package with an error. This
4624 mechanism is specifically designed to produce an error when
4625 the installed package is <tt>Essential</tt>, but the new
4630 A package will not cause a conflict merely because its
4631 configuration files are still installed; it must be at least
4636 A special exception is made for packages which declare a
4637 conflict with their own package name, or with a virtual
4638 package which they provide (see below): this does not
4639 prevent their installation, and allows a package to conflict
4640 with others providing a replacement for it. You use this
4641 feature when you want the package in question to be the only
4642 package providing some feature.
4646 A <tt>Conflicts</tt> entry should almost never have an
4647 "earlier than" version clause. This would prevent
4648 <prgn>dpkg</prgn> from upgrading or installing the package
4649 which declared such a conflict until the upgrade or removal
4650 of the conflicted-with package had been completed. Instead,
4651 <tt>Breaks</tt> may be used.
4655 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4659 As well as the names of actual ("concrete") packages, the
4660 package relationship fields <tt>Depends</tt>,
4661 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4662 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4663 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4664 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4665 may mention "virtual packages".
4669 A <em>virtual package</em> is one which appears in the
4670 <tt>Provides</tt> control file field of another package.
4671 The effect is as if the package(s) which provide a
4672 particular virtual package name had been listed by name
4673 everywhere the virtual package name appears. (See also <ref
4678 If there are both concrete and virtual packages of the same
4679 name, then the dependency may be satisfied (or the conflict
4680 caused) by either the concrete package with the name in
4681 question or any other concrete package which provides the
4682 virtual package with the name in question. This is so that,
4683 for example, supposing we have
4684 <example compact="compact">
4687 </example> and someone else releases an enhanced version of
4688 the <tt>bar</tt> package they can say:
4689 <example compact="compact">
4693 and the <tt>bar-plus</tt> package will now also satisfy the
4694 dependency for the <tt>foo</tt> package.
4698 If a relationship field has a version number attached
4699 then only real packages will be considered to see whether
4700 the relationship is satisfied (or the prohibition violated,
4701 for a conflict or breakage) - it is assumed that a real
4702 package which provides the virtual package is not of the
4703 "right" version. So, a <tt>Provides</tt> field may not
4704 contain version numbers, and the version number of the
4705 concrete package which provides a particular virtual package
4706 will not be looked at when considering a dependency on or
4707 conflict with the virtual package name.
4711 It is likely that the ability will be added in a future
4712 release of <prgn>dpkg</prgn> to specify a version number for
4713 each virtual package it provides. This feature is not yet
4714 present, however, and is expected to be used only
4719 If you want to specify which of a set of real packages
4720 should be the default to satisfy a particular dependency on
4721 a virtual package, you should list the real package as an
4722 alternative before the virtual one.
4727 <sect id="replaces"><heading>Overwriting files and replacing
4728 packages - <tt>Replaces</tt></heading>
4731 Packages can declare in their control file that they should
4732 overwrite files in certain other packages, or completely
4733 replace other packages. The <tt>Replaces</tt> control file
4734 field has these two distinct purposes.
4737 <sect1><heading>Overwriting files in other packages</heading>
4740 Firstly, as mentioned before, it is usually an error for a
4741 package to contain files which are on the system in
4746 However, if the overwriting package declares that it
4747 <tt>Replaces</tt> the one containing the file being
4748 overwritten, then <prgn>dpkg</prgn> will replace the file
4749 from the old package with that from the new. The file
4750 will no longer be listed as "owned" by the old package.
4754 For example, if a package <package>foo</package> is split
4755 into <package>foo</package> and <package>foo-data</package>
4756 starting at version 1.2-3, <package>foo-data</package> should
4758 <example compact="compact">
4759 Replaces: foo (<< 1.2-3)
4761 in its control file. The package <package>foo</package>
4762 doesn't need any special control fields in this example,
4763 although would generally depend on or
4764 recommend <package>foo-data</package>.
4768 If a package is completely replaced in this way, so that
4769 <prgn>dpkg</prgn> does not know of any files it still
4770 contains, it is considered to have "disappeared". It will
4771 be marked as not wanted on the system (selected for
4772 removal) and not installed. Any <tt>conffile</tt>s
4773 details noted for the package will be ignored, as they
4774 will have been taken over by the overwriting package. The
4775 package's <prgn>postrm</prgn> script will be run with a
4776 special argument to allow the package to do any final
4777 cleanup required. See <ref id="mscriptsinstact">.
4780 Replaces is a one way relationship -- you have to
4781 install the replacing package after the replaced
4788 For this usage of <tt>Replaces</tt>, virtual packages (see
4789 <ref id="virtual">) are not considered when looking at a
4790 <tt>Replaces</tt> field - the packages declared as being
4791 replaced must be mentioned by their real names.
4795 Furthermore, this usage of <tt>Replaces</tt> only takes
4796 effect when both packages are at least partially on the
4797 system at once, so that it can only happen if they do not
4798 conflict or if the conflict has been overridden.
4803 <sect1><heading>Replacing whole packages, forcing their
4807 Secondly, <tt>Replaces</tt> allows the packaging system to
4808 resolve which package should be removed when there is a
4809 conflict - see <ref id="conflicts">. This usage only
4810 takes effect when the two packages <em>do</em> conflict,
4811 so that the two usages of this field do not interfere with
4816 In this situation, the package declared as being replaced
4817 can be a virtual package, so for example, all mail
4818 transport agents (MTAs) would have the following fields in
4819 their control files:
4820 <example compact="compact">
4821 Provides: mail-transport-agent
4822 Conflicts: mail-transport-agent
4823 Replaces: mail-transport-agent
4825 ensuring that only one MTA can be installed at any one
4830 <sect id="sourcebinarydeps">
4831 <heading>Relationships between source and binary packages -
4832 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4833 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4837 Source packages that require certain binary packages to be
4838 installed or absent at the time of building the package
4839 can declare relationships to those binary packages.
4843 This is done using the <tt>Build-Depends</tt>,
4844 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4845 <tt>Build-Conflicts-Indep</tt> control file fields.
4849 Build-dependencies on "build-essential" binary packages can be
4850 omitted. Please see <ref id="pkg-relations"> for more information.
4854 The dependencies and conflicts they define must be satisfied
4855 (as defined earlier for binary packages) in order to invoke
4856 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4858 There is no Build-Depends-Arch; this role is essentially
4859 met with Build-Depends. Anyone building the
4860 <tt>build-indep</tt> and binary-indep<tt></tt> targets is
4861 assumed to be building the whole package, and therefore
4862 installation of all build dependencies is required.
4865 The autobuilders use <tt>dpkg-buildpackage -B</tt>, which
4866 calls <tt>build</tt>, not <tt>build-arch</tt> since it does
4867 not yet know how to check for its existence, and
4868 <tt>binary-arch</tt>. The purpose of the original split
4869 between <tt>Build-Depends</tt> and
4870 <tt>Build-Depends-Indep</tt> was so that the autobuilders
4871 wouldn't need to install extra packages needed only for the
4872 binary-indep targets. But without a build-arch/build-indep
4873 split, this didn't work, since most of the work is done in
4874 the build target, not in the binary target.
4878 <tag><tt>clean</tt>, <tt>build-arch</tt>, and
4879 <tt>binary-arch</tt></tag>
4881 Only the <tt>Build-Depends</tt> and <tt>Build-Conflicts</tt>
4882 fields must be satisfied when these targets are invoked.
4884 <tag><tt>build</tt>, <tt>build-indep</tt>, <tt>binary</tt>,
4885 and <tt>binary-indep</tt></tag>
4887 The <tt>Build-Depends</tt>, <tt>Build-Conflicts</tt>,
4888 <tt>Build-Depends-Indep</tt>, and
4889 <tt>Build-Conflicts-Indep</tt> fields must be satisfied when
4890 these targets are invoked.
4898 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4901 Packages containing shared libraries must be constructed with
4902 a little care to make sure that the shared library is always
4903 available. This is especially important for packages whose
4904 shared libraries are vitally important, such as the C library
4905 (currently <tt>libc6</tt>).
4909 Packages involving shared libraries should be split up into
4910 several binary packages. This section mostly deals with how
4911 this separation is to be accomplished; rules for files within
4912 the shared library packages are in <ref id="libraries"> instead.
4915 <sect id="sharedlibs-runtime">
4916 <heading>Run-time shared libraries</heading>
4919 The run-time shared library needs to be placed in a package
4920 whose name changes whenever the shared object version
4923 Since it is common place to install several versions of a
4924 package that just provides shared libraries, it is a
4925 good idea that the library package should not
4926 contain any extraneous non-versioned files, unless they
4927 happen to be in versioned directories.</p>
4929 The most common mechanism is to place it in a package
4931 <package><var>libraryname</var><var>soversion</var></package>,
4932 where <file><var>soversion</var></file> is the version number
4933 in the soname of the shared library<footnote>
4934 The soname is the shared object name: it's the thing
4935 that has to match exactly between building an executable
4936 and running it for the dynamic linker to be able run the
4937 program. For example, if the soname of the library is
4938 <file>libfoo.so.6</file>, the library package would be
4939 called <file>libfoo6</file>.
4941 Alternatively, if it would be confusing to directly append
4942 <var>soversion</var> to <var>libraryname</var> (e.g. because
4943 <var>libraryname</var> itself ends in a number), you may use
4944 <package><var>libraryname</var>-<var>soversion</var></package> and
4945 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4950 If you have several shared libraries built from the same
4951 source tree you may lump them all together into a single
4952 shared library package, provided that you change all of
4953 their sonames at once (so that you don't get filename
4954 clashes if you try to install different versions of the
4955 combined shared libraries package).
4959 The package should install the shared libraries under
4960 their normal names. For example, the <package>libgdbm3</package>
4961 package should install <file>libgdbm.so.3.0.0</file> as
4962 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4963 renamed or re-linked by any <prgn>prerm</prgn> or
4964 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4965 of renaming things safely without affecting running programs,
4966 and attempts to interfere with this are likely to lead to
4971 Shared libraries should not be installed executable, since
4972 the dynamic linker does not require this and trying to
4973 execute a shared library usually results in a core dump.
4977 The run-time library package should include the symbolic link that
4978 <prgn>ldconfig</prgn> would create for the shared libraries.
4979 For example, the <package>libgdbm3</package> package should include
4980 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4981 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4982 linker (for example <prgn>ld.so</prgn> or
4983 <prgn>ld-linux.so.*</prgn>) can find the library between the
4984 time that <prgn>dpkg</prgn> installs it and the time that
4985 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4987 The package management system requires the library to be
4988 placed before the symbolic link pointing to it in the
4989 <file>.deb</file> file. This is so that when
4990 <prgn>dpkg</prgn> comes to install the symlink
4991 (overwriting the previous symlink pointing at an older
4992 version of the library), the new shared library is already
4993 in place. In the past, this was achieved by creating the
4994 library in the temporary packaging directory before
4995 creating the symlink. Unfortunately, this was not always
4996 effective, since the building of the tar file in the
4997 <file>.deb</file> depended on the behavior of the underlying
4998 file system. Some file systems (such as reiserfs) reorder
4999 the files so that the order of creation is forgotten.
5000 Since version 1.7.0, <prgn>dpkg</prgn>
5001 reorders the files itself as necessary when building a
5002 package. Thus it is no longer important to concern
5003 oneself with the order of file creation.
5007 <sect1 id="ldconfig">
5008 <heading><tt>ldconfig</tt></heading>
5011 Any package installing shared libraries in one of the default
5012 library directories of the dynamic linker (which are currently
5013 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
5014 listed in <file>/etc/ld.so.conf</file><footnote>
5016 <list compact="compact">
5017 <item>/usr/local/lib</item>
5018 <item>/usr/lib/libc5-compat</item>
5019 <item>/lib/libc5-compat</item>
5022 must use <prgn>ldconfig</prgn> to update the shared library
5027 The package maintainer scripts must only call
5028 <prgn>ldconfig</prgn> under these circumstances:
5029 <list compact="compact">
5030 <item>When the <prgn>postinst</prgn> script is run with a
5031 first argument of <tt>configure</tt>, the script must call
5032 <prgn>ldconfig</prgn>, and may optionally invoke
5033 <prgn>ldconfig</prgn> at other times.
5035 <item>When the <prgn>postrm</prgn> script is run with a
5036 first argument of <tt>remove</tt>, the script should call
5037 <prgn>ldconfig</prgn>.
5042 During install or upgrade, the preinst is called before
5043 the new files are installed, so calling "ldconfig" is
5044 pointless. The preinst of an existing package can also be
5045 called if an upgrade fails. However, this happens during
5046 the critical time when a shared libs may exist on-disk
5047 under a temporary name. Thus, it is dangerous and
5048 forbidden by current policy to call "ldconfig" at this
5053 When a package is installed or upgraded, "postinst
5054 configure" runs after the new files are safely on-disk.
5055 Since it is perfectly safe to invoke ldconfig
5056 unconditionally in a postinst, it is OK for a package to
5057 simply put ldconfig in its postinst without checking the
5058 argument. The postinst can also be called to recover from
5059 a failed upgrade. This happens before any new files are
5060 unpacked, so there is no reason to call "ldconfig" at this
5065 For a package that is being removed, prerm is
5066 called with all the files intact, so calling ldconfig is
5067 useless. The other calls to "prerm" happen in the case of
5068 upgrade at a time when all the files of the old package
5069 are on-disk, so again calling "ldconfig" is pointless.
5073 postrm, on the other hand, is called with the "remove"
5074 argument just after the files are removed, so this is
5075 the proper time to call "ldconfig" to notify the system
5076 of the fact that the shared libraries from the package
5077 are removed. The postrm can be called at several other
5078 times. At the time of "postrm purge", "postrm
5079 abort-install", or "postrm abort-upgrade", calling
5080 "ldconfig" is useless because the shared lib files are
5081 not on-disk. However, when "postrm" is invoked with
5082 arguments "upgrade", "failed-upgrade", or "disappear", a
5083 shared lib may exist on-disk under a temporary filename.
5091 <sect id="sharedlibs-support-files">
5092 <heading>Shared library support files</heading>
5095 If your package contains files whose names do not change with
5096 each change in the library shared object version, you must not
5097 put them in the shared library package. Otherwise, several
5098 versions of the shared library cannot be installed at the same
5099 time without filename clashes, making upgrades and transitions
5100 unnecessarily difficult.
5104 It is recommended that supporting files and run-time support
5105 programs that do not need to be invoked manually by users, but
5106 are nevertheless required for the package to function, be placed
5107 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
5108 preferably under <file>/usr/lib/</file><var>package-name</var>.
5109 If the program or file is architecture independent, the
5110 recommendation is for it to be placed in a subdirectory of
5111 <file>/usr/share</file> instead, preferably under
5112 <file>/usr/share/</file><var>package-name</var>. Following the
5113 <var>package-name</var> naming convention ensures that the file
5114 names change when the shared object version changes.
5118 Run-time support programs that use the shared library but are
5119 not required for the library to function or files used by the
5120 shared library that can be used by any version of the shared
5121 library package should instead be put in a separate package.
5122 This package might typically be named
5123 <package><var>libraryname</var>-tools</package>; note the
5124 absence of the <var>soversion</var> in the package name.
5128 Files and support programs only useful when compiling software
5129 against the library should be included in the development
5130 package for the library.<footnote>
5131 For example, a <file><var>package-name</var>-config</file>
5132 script or <package>pkg-config</package> configuration files.
5137 <sect id="sharedlibs-static">
5138 <heading>Static libraries</heading>
5141 The static library (<file><var>libraryname.a</var></file>)
5142 is usually provided in addition to the shared version.
5143 It is placed into the development package (see below).
5147 In some cases, it is acceptable for a library to be
5148 available in static form only; these cases include:
5150 <item>libraries for languages whose shared library support
5151 is immature or unstable</item>
5152 <item>libraries whose interfaces are in flux or under
5153 development (commonly the case when the library's
5154 major version number is zero, or where the ABI breaks
5155 across patchlevels)</item>
5156 <item>libraries which are explicitly intended to be
5157 available only in static form by their upstream
5162 <sect id="sharedlibs-dev">
5163 <heading>Development files</heading>
5166 If there are development files associated with a shared library,
5167 the source package needs to generate a binary development package
5168 named <package><var>libraryname</var><var>soversion</var>-dev</package>,
5169 or if you prefer only to support one development version at a
5170 time, <package><var>libraryname</var>-dev</package>. Installing
5171 the development package must result in installation of all the
5172 development files necessary for compiling programs against that
5173 shared library.<footnote>
5174 This wording allows the development files to be split into
5175 several packages, such as a separate architecture-independent
5176 <package><var>libraryname</var>-headers</package>, provided that
5177 the development package depends on all the required additional
5183 In case several development versions of a library exist, you may
5184 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5185 <ref id="conflicts">) to ensure that the user only installs one
5186 development version at a time (as different development versions are
5187 likely to have the same header files in them, which would cause a
5188 filename clash if both were installed).
5192 The development package should contain a symlink for the associated
5193 shared library without a version number. For example, the
5194 <package>libgdbm-dev</package> package should include a symlink
5195 from <file>/usr/lib/libgdbm.so</file> to
5196 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5197 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5198 <file>libgdbm.so</file> when compiling dynamically.
5202 <sect id="sharedlibs-intradeps">
5203 <heading>Dependencies between the packages of the same library</heading>
5206 Typically the development version should have an exact
5207 version dependency on the runtime library, to make sure that
5208 compilation and linking happens correctly. The
5209 <tt>${binary:Version}</tt> substitution variable can be
5210 useful for this purpose.
5212 Previously, <tt>${Source-Version}</tt> was used, but its name
5213 was confusing and it has been deprecated since dpkg 1.13.19.
5218 <sect id="sharedlibs-shlibdeps">
5219 <heading>Dependencies between the library and other packages -
5220 the <tt>shlibs</tt> system</heading>
5223 If a package contains a binary or library which links to a
5224 shared library, we must ensure that when the package is
5225 installed on the system, all of the libraries needed are
5226 also installed. This requirement led to the creation of the
5227 <tt>shlibs</tt> system, which is very simple in its design:
5228 any package which <em>provides</em> a shared library also
5229 provides information on the package dependencies required to
5230 ensure the presence of this library, and any package which
5231 <em>uses</em> a shared library uses this information to
5232 determine the dependencies it requires. The files which
5233 contain the mapping from shared libraries to the necessary
5234 dependency information are called <file>shlibs</file> files.
5238 Thus, when a package is built which contains any shared
5239 libraries, it must provide a <file>shlibs</file> file for other
5240 packages to use, and when a package is built which contains
5241 any shared libraries or compiled binaries, it must run
5242 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5243 on these to determine the libraries used and hence the
5244 dependencies needed by this package.<footnote>
5246 In the past, the shared libraries linked to were
5247 determined by calling <prgn>ldd</prgn>, but now
5248 <prgn>objdump</prgn> is used to do this. The only
5249 change this makes to package building is that
5250 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
5251 libraries, whereas in the past this was unnecessary.
5252 The rest of this footnote explains the advantage that
5257 We say that a binary <tt>foo</tt> <em>directly</em> uses
5258 a library <tt>libbar</tt> if it is explicitly linked
5259 with that library (that is, it uses the flag
5260 <tt>-lbar</tt> during the linking stage). Other
5261 libraries that are needed by <tt>libbar</tt> are linked
5262 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5263 linker will load them automatically when it loads
5264 <tt>libbar</tt>. A package should depend on
5265 the libraries it directly uses, and the dependencies for
5266 those libraries should automatically pull in the other
5271 Unfortunately, the <prgn>ldd</prgn> program shows both
5272 the directly and indirectly used libraries, meaning that
5273 the dependencies determined included both direct and
5274 indirect dependencies. The use of <prgn>objdump</prgn>
5275 avoids this problem by determining only the directly
5280 A good example of where this helps is the following. We
5281 could update <tt>libimlib</tt> with a new version that
5282 supports a new graphics format called dgf (but retaining
5283 the same major version number). If we used the old
5284 <prgn>ldd</prgn> method, every package that uses
5285 <tt>libimlib</tt> would need to be recompiled so it
5286 would also depend on <tt>libdgf</tt> or it wouldn't run
5287 due to missing symbols. However with the new system,
5288 packages using <tt>libimlib</tt> can rely on
5289 <tt>libimlib</tt> itself having the dependency on
5290 <tt>libdgf</tt> and so they would not need rebuilding.
5296 In the following sections, we will first describe where the
5297 various <tt>shlibs</tt> files are to be found, then how to
5298 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5299 file format and how to create them if your package contains a
5304 <heading>The <tt>shlibs</tt> files present on the system</heading>
5307 There are several places where <tt>shlibs</tt> files are
5308 found. The following list gives them in the order in which
5310 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5311 (The first one which gives the required information is used.)
5317 <p><file>debian/shlibs.local</file></p>
5320 This lists overrides for this package. Its use is
5321 described below (see <ref id="shlibslocal">).
5326 <p><file>/etc/dpkg/shlibs.override</file></p>
5329 This lists global overrides. This list is normally
5330 empty. It is maintained by the local system
5336 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5339 When packages are being built, any
5340 <file>debian/shlibs</file> files are copied into the
5341 control file area of the temporary build directory and
5342 given the name <file>shlibs</file>. These files give
5343 details of any shared libraries included in the
5345 An example may help here. Let us say that the
5346 source package <tt>foo</tt> generates two binary
5347 packages, <tt>libfoo2</tt> and
5348 <tt>foo-runtime</tt>. When building the binary
5349 packages, the two packages are created in the
5350 directories <file>debian/libfoo2</file> and
5351 <file>debian/foo-runtime</file> respectively.
5352 (<file>debian/tmp</file> could be used instead of one
5353 of these.) Since <tt>libfoo2</tt> provides the
5354 <tt>libfoo</tt> shared library, it will require a
5355 <tt>shlibs</tt> file, which will be installed in
5356 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
5358 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
5359 when <prgn>dpkg-shlibdeps</prgn> is run on the
5361 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
5363 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5364 determine whether <tt>foo-prog</tt>'s library
5365 dependencies are satisfied by any of the libraries
5366 provided by <tt>libfoo2</tt>. For this reason,
5367 <prgn>dpkg-shlibdeps</prgn> must only be run once
5368 all of the individual binary packages'
5369 <tt>shlibs</tt> files have been installed into the
5376 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5379 These are the <file>shlibs</file> files corresponding to
5380 all of the packages installed on the system, and are
5381 maintained by the relevant package maintainers.
5386 <p><file>/etc/dpkg/shlibs.default</file></p>
5389 This file lists any shared libraries whose packages
5390 have failed to provide correct <file>shlibs</file> files.
5391 It was used when the <file>shlibs</file> setup was first
5392 introduced, but it is now normally empty. It is
5393 maintained by the <tt>dpkg</tt> maintainer.
5401 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5402 <file>shlibs</file> files</heading>
5406 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5407 into your <file>debian/rules</file> file. If your package
5408 contains only compiled binaries and libraries (but no scripts),
5409 you can use a command such as:
5410 <example compact="compact">
5411 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5412 debian/tmp/usr/lib/*
5414 Otherwise, you will need to explicitly list the compiled
5415 binaries and libraries.<footnote>
5416 If you are using <tt>debhelper</tt>, the
5417 <prgn>dh_shlibdeps</prgn> program will do this work for
5418 you. It will also correctly handle multi-binary
5424 This command puts the dependency information into the
5425 <file>debian/substvars</file> file, which is then used by
5426 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5427 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5428 field in the control file for this to work.
5432 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
5433 done. If it does complain you might need to create your own
5434 <file>debian/shlibs.local</file> file, as explained below (see
5435 <ref id="shlibslocal">).
5439 If you have multiple binary packages, you will need to call
5440 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5441 compiled libraries or binaries. In such a case, you will
5442 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5443 utilities to specify a different <file>substvars</file> file.
5447 If you are creating a udeb for use in the Debian Installer,
5448 you will need to specify that <prgn>dpkg-shlibdeps</prgn>
5449 should use the dependency line of type <tt>udeb</tt> by
5450 adding the <tt>-tudeb</tt> option<footnote>
5451 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5452 will automatically add this option if it knows it is
5454 </footnote>. If there is no dependency line of type <tt>udeb</tt>
5455 in the <file>shlibs</file> file, <prgn>dpkg-shlibdeps</prgn> will
5456 fall back to the regular dependency line.
5460 For more details on dpkg-shlibdeps, please see
5461 <ref id="pkg-dpkg-shlibdeps"> and
5462 <manref name="dpkg-shlibdeps" section="1">.
5467 <heading>The <file>shlibs</file> File Format</heading>
5470 Each <file>shlibs</file> file has the same format. Lines
5471 beginning with <tt>#</tt> are considered to be comments and
5472 are ignored. Each line is of the form:
5473 <example compact="compact">
5474 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5479 We will explain this by reference to the example of the
5480 <tt>zlib1g</tt> package, which (at the time of writing)
5481 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5485 <var>type</var> is an optional element that indicates the type
5486 of package for which the line is valid. The only type currently
5487 in use is <tt>udeb</tt>. The colon and space after the type are
5492 <var>library-name</var> is the name of the shared library,
5493 in this case <tt>libz</tt>. (This must match the name part
5494 of the soname, see below.)
5498 <var>soname-version</var> is the version part of the soname of
5499 the library. The soname is the thing that must exactly match
5500 for the library to be recognized by the dynamic linker, and is
5502 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5503 example, <tt>libz.so.1</tt>.<footnote>
5504 This can be determined using the command
5505 <example compact="compact">
5506 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5509 The version part is the part which comes after
5510 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
5514 <var>dependencies</var> has the same syntax as a dependency
5515 field in a binary package control file. It should give
5516 details of which packages are required to satisfy a binary
5517 built against the version of the library contained in the
5518 package. See <ref id="depsyntax"> for details.
5522 In our example, if the first version of the <tt>zlib1g</tt>
5523 package which contained a minor number of at least
5524 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5525 <tt>shlibs</tt> entry for this library could say:
5526 <example compact="compact">
5527 libz 1 zlib1g (>= 1:1.1.3)
5529 The version-specific dependency is to avoid warnings from
5530 the dynamic linker about using older shared libraries with
5535 As zlib1g also provides a udeb containing the shared library,
5536 there would also be a second line:
5537 <example compact="compact">
5538 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5544 <heading>Providing a <file>shlibs</file> file</heading>
5547 If your package provides a shared library, you need to create
5548 a <file>shlibs</file> file following the format described above.
5549 It is usual to call this file <file>debian/shlibs</file> (but if
5550 you have multiple binary packages, you might want to call it
5551 <file>debian/shlibs.<var>package</var></file> instead). Then
5552 let <file>debian/rules</file> install it in the control area:
5553 <example compact="compact">
5554 install -m644 debian/shlibs debian/tmp/DEBIAN
5556 or, in the case of a multi-binary package:
5557 <example compact="compact">
5558 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5560 An alternative way of doing this is to create the
5561 <file>shlibs</file> file in the control area directly from
5562 <file>debian/rules</file> without using a <file>debian/shlibs</file>
5563 file at all,<footnote>
5564 This is what <prgn>dh_makeshlibs</prgn> in the
5565 <tt>debhelper</tt> suite does. If your package also has a udeb
5566 that provides a shared library, <prgn>dh_makeshlibs</prgn> can
5567 automatically generate the <tt>udeb:</tt> lines if you specify
5568 the name of the udeb with the <tt>--add-udeb</tt> option.
5570 since the <file>debian/shlibs</file> file itself is ignored by
5571 <prgn>dpkg-shlibdeps</prgn>.
5575 As <prgn>dpkg-shlibdeps</prgn> reads the
5576 <file>DEBIAN/shlibs</file> files in all of the binary packages
5577 being built from this source package, all of the
5578 <file>DEBIAN/shlibs</file> files should be installed before
5579 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5584 <sect1 id="shlibslocal">
5585 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
5588 This file is intended only as a <em>temporary</em> fix if
5589 your binaries or libraries depend on a library whose package
5590 does not yet provide a correct <file>shlibs</file> file.
5594 We will assume that you are trying to package a binary
5595 <tt>foo</tt>. When you try running
5596 <prgn>dpkg-shlibdeps</prgn> you get the following error
5597 message (<tt>-O</tt> displays the dependency information on
5598 <tt>stdout</tt> instead of writing it to
5599 <tt>debian/substvars</tt>, and the lines have been wrapped
5600 for ease of reading):
5601 <example compact="compact">
5602 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
5603 dpkg-shlibdeps: warning: unable to find dependency
5604 information for shared library libbar (soname 1,
5605 path /usr/lib/libbar.so.1, dependency field Depends)
5606 shlibs:Depends=libc6 (>= 2.2.2-2)
5608 You can then run <prgn>ldd</prgn> on the binary to find the
5609 full location of the library concerned:
5610 <example compact="compact">
5612 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5613 libc.so.6 => /lib/libc.so.6 (0x40032000)
5614 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5616 So the <prgn>foo</prgn> binary depends on the
5617 <prgn>libbar</prgn> shared library, but no package seems to
5618 provide a <file>*.shlibs</file> file handling
5619 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5620 determine the package responsible:
5621 <example compact="compact">
5622 $ dpkg -S /usr/lib/libbar.so.1
5623 bar1: /usr/lib/libbar.so.1
5624 $ dpkg -s bar1 | grep Version
5627 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5628 is the one we are using. Now we can file a bug against the
5629 <tt>bar1</tt> package and create our own
5630 <file>debian/shlibs.local</file> to locally fix the problem.
5631 Including the following line into your
5632 <file>debian/shlibs.local</file> file:
5633 <example compact="compact">
5634 libbar 1 bar1 (>= 1.0-1)
5636 should allow the package build to work.
5640 As soon as the maintainer of <tt>bar1</tt> provides a
5641 correct <file>shlibs</file> file, you should remove this line
5642 from your <file>debian/shlibs.local</file> file. (You should
5643 probably also then have a versioned <tt>Build-Depends</tt>
5644 on <tt>bar1</tt> to help ensure that others do not have the
5645 same problem building your package.)
5654 <chapt id="opersys"><heading>The Operating System</heading>
5657 <heading>File system hierarchy</heading>
5661 <heading>File System Structure</heading>
5664 The location of all installed files and directories must
5665 comply with the Filesystem Hierarchy Standard (FHS),
5666 version 2.3, with the exceptions noted below, and except
5667 where doing so would violate other terms of Debian
5668 Policy. The following exceptions to the FHS apply:
5673 The optional rules related to user specific
5674 configuration files for applications are stored in
5675 the user's home directory are relaxed. It is
5676 recommended that such files start with the
5677 '<tt>.</tt>' character (a "dot file"), and if an
5678 application needs to create more than one dot file
5679 then the preferred placement is in a subdirectory
5680 with a name starting with a '.' character, (a "dot
5681 directory"). In this case it is recommended the
5682 configuration files not start with the '.'
5688 The requirement for amd64 to use <file>/lib64</file>
5689 for 64 bit binaries is removed.
5694 The requirement for object files, internal binaries, and
5695 libraries, including <file>libc.so.*</file>, to be located
5696 directly under <file>/lib{,32}</file> and
5697 <file>/usr/lib{,32}</file> is amended, permitting files
5698 to instead be installed to
5699 <file>/lib/<var>triplet</var></file> and
5700 <file>/usr/lib/<var>triplet</var></file>, where
5701 <tt><var>triplet</var></tt> is the value returned by
5702 <tt>dpkg-architecture -qDEB_HOST_GNU_TYPE</tt> for the
5703 architecture of the package. Packages may <em>not</em>
5704 install files to any <var>triplet</var> path other
5705 than the one matching the architecture of that package;
5706 for instance, an <tt>Architecture: amd64</tt> package
5707 containing 32-bit x86 libraries may not install these
5708 libraries to <file>/usr/lib/i486-linux-gnu</file>.
5710 This is necessary in order to reserve the directories for
5711 use in cross-installation of library packages from other
5712 architectures, as part of the planned deployment of
5717 Applications may also use a single subdirectory under
5718 <file>/usr/lib/<var>triplet</var></file>.
5721 The execution time linker/loader, ld*, must still be made
5722 available in the existing location under /lib or /lib64
5723 since this is part of the ELF ABI for the architecture.
5728 The requirement that
5729 <file>/usr/local/share/man</file> be "synonymous"
5730 with <file>/usr/local/man</file> is relaxed to a
5735 The requirement that windowmanagers with a single
5736 configuration file call it <file>system.*wmrc</file>
5737 is removed, as is the restriction that the window
5738 manager subdirectory be named identically to the
5739 window manager name itself.
5744 The requirement that boot manager configuration
5745 files live in <file>/etc</file>, or at least are
5746 symlinked there, is relaxed to a recommendation.
5751 The following directories in the root filesystem are
5752 additionally allowed: <file>/sys</file> and
5753 <file>/selinux</file>. <footnote>These directories
5754 are used as mount points to mount virtual filesystems
5755 to get access to kernel information.</footnote>
5762 The version of this document referred here can be
5763 found in the <tt>debian-policy</tt> package or on <url
5764 id="http://www.debian.org/doc/packaging-manuals/fhs/"
5765 name="FHS (Debian copy)"> alongside this manual (or, if
5766 you have the <package>debian-policy</package> installed,
5768 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5769 (local copy)">). The
5770 latest version, which may be a more recent version, may
5772 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5773 Specific questions about following the standard may be
5774 asked on the <tt>debian-devel</tt> mailing list, or
5775 referred to the FHS mailing list (see the
5776 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5782 <heading>Site-specific programs</heading>
5785 As mandated by the FHS, packages must not place any
5786 files in <file>/usr/local</file>, either by putting them in
5787 the file system archive to be unpacked by <prgn>dpkg</prgn>
5788 or by manipulating them in their maintainer scripts.
5792 However, the package may create empty directories below
5793 <file>/usr/local</file> so that the system administrator knows
5794 where to place site-specific files. These are not
5795 directories <em>in</em> <file>/usr/local</file>, but are
5796 children of directories in <file>/usr/local</file>. These
5797 directories (<file>/usr/local/*/dir/</file>)
5798 should be removed on package removal if they are
5803 Note that this applies only to
5804 directories <em>below</em> <file>/usr/local</file>,
5805 not <em>in</em> <file>/usr/local</file>. Packages must
5806 not create sub-directories in the
5807 directory <file>/usr/local</file> itself, except those
5808 listed in FHS, section 4.5. However, you may create
5809 directories below them as you wish. You must not remove
5810 any of the directories listed in 4.5, even if you created
5815 Since <file>/usr/local</file> can be mounted read-only from a
5816 remote server, these directories must be created and
5817 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5818 maintainer scripts and not be included in the
5819 <file>.deb</file> archive. These scripts must not fail if
5820 either of these operations fail.
5824 For example, the <tt>emacsen-common</tt> package could
5825 contain something like
5826 <example compact="compact">
5827 if [ ! -e /usr/local/share/emacs ]
5829 if mkdir /usr/local/share/emacs 2>/dev/null
5831 chown root:staff /usr/local/share/emacs
5832 chmod 2775 /usr/local/share/emacs
5836 in its <prgn>postinst</prgn> script, and
5837 <example compact="compact">
5838 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5839 rmdir /usr/local/share/emacs 2>/dev/null || true
5841 in the <prgn>prerm</prgn> script. (Note that this form is
5842 used to ensure that if the script is interrupted, the
5843 directory <file>/usr/local/share/emacs</file> will still be
5848 If you do create a directory in <file>/usr/local</file> for
5849 local additions to a package, you should ensure that
5850 settings in <file>/usr/local</file> take precedence over the
5851 equivalents in <file>/usr</file>.
5855 However, because <file>/usr/local</file> and its contents are
5856 for exclusive use of the local administrator, a package
5857 must not rely on the presence or absence of files or
5858 directories in <file>/usr/local</file> for normal operation.
5862 The <file>/usr/local</file> directory itself and all the
5863 subdirectories created by the package should (by default) have
5864 permissions 2775 (group-writable and set-group-id) and be
5865 owned by <tt>root:staff</tt>.
5870 <heading>The system-wide mail directory</heading>
5872 The system-wide mail directory
5873 is <file>/var/mail</file>. This directory is part of the
5874 base system and should not be owned by any particular mail
5875 agents. The use of the old
5876 location <file>/var/spool/mail</file> is deprecated, even
5877 though the spool may still be physically located there.
5883 <heading>Users and groups</heading>
5886 <heading>Introduction</heading>
5888 The Debian system can be configured to use either plain or
5893 Some user ids (UIDs) and group ids (GIDs) are reserved
5894 globally for use by certain packages. Because some
5895 packages need to include files which are owned by these
5896 users or groups, or need the ids compiled into binaries,
5897 these ids must be used on any Debian system only for the
5898 purpose for which they are allocated. This is a serious
5899 restriction, and we should avoid getting in the way of
5900 local administration policies. In particular, many sites
5901 allocate users and/or local system groups starting at 100.
5905 Apart from this we should have dynamically allocated ids,
5906 which should by default be arranged in some sensible
5907 order, but the behavior should be configurable.
5911 Packages other than <tt>base-passwd</tt> must not modify
5912 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5913 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5918 <heading>UID and GID classes</heading>
5920 The UID and GID numbers are divided into classes as
5926 Globally allocated by the Debian project, the same
5927 on every Debian system. These ids will appear in
5928 the <file>passwd</file> and <file>group</file> files of all
5929 Debian systems, new ids in this range being added
5930 automatically as the <tt>base-passwd</tt> package is
5935 Packages which need a single statically allocated
5936 uid or gid should use one of these; their
5937 maintainers should ask the <tt>base-passwd</tt>
5945 Dynamically allocated system users and groups.
5946 Packages which need a user or group, but can have
5947 this user or group allocated dynamically and
5948 differently on each system, should use <tt>adduser
5949 --system</tt> to create the group and/or user.
5950 <prgn>adduser</prgn> will check for the existence of
5951 the user or group, and if necessary choose an unused
5952 id based on the ranges specified in
5953 <file>adduser.conf</file>.
5957 <tag>1000-59999:</tag>
5960 Dynamically allocated user accounts. By default
5961 <prgn>adduser</prgn> will choose UIDs and GIDs for
5962 user accounts in this range, though
5963 <file>adduser.conf</file> may be used to modify this
5968 <tag>60000-64999:</tag>
5971 Globally allocated by the Debian project, but only
5972 created on demand. The ids are allocated centrally
5973 and statically, but the actual accounts are only
5974 created on users' systems on demand.
5978 These ids are for packages which are obscure or
5979 which require many statically-allocated ids. These
5980 packages should check for and create the accounts in
5981 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5982 <prgn>adduser</prgn> if it has this facility) if
5983 necessary. Packages which are likely to require
5984 further allocations should have a "hole" left after
5985 them in the allocation, to give them room to
5990 <tag>65000-65533:</tag>
5998 User <tt>nobody</tt>. The corresponding gid refers
5999 to the group <tt>nogroup</tt>.
6006 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
6007 not</em> be used, because it is the error return
6016 <sect id="sysvinit">
6017 <heading>System run levels and <file>init.d</file> scripts</heading>
6019 <sect1 id="/etc/init.d">
6020 <heading>Introduction</heading>
6023 The <file>/etc/init.d</file> directory contains the scripts
6024 executed by <prgn>init</prgn> at boot time and when the
6025 init state (or "runlevel") is changed (see <manref
6026 name="init" section="8">).
6030 There are at least two different, yet functionally
6031 equivalent, ways of handling these scripts. For the sake
6032 of simplicity, this document describes only the symbolic
6033 link method. However, it must not be assumed by maintainer
6034 scripts that this method is being used, and any automated
6035 manipulation of the various runlevel behaviors by
6036 maintainer scripts must be performed using
6037 <prgn>update-rc.d</prgn> as described below and not by
6038 manually installing or removing symlinks. For information
6039 on the implementation details of the other method,
6040 implemented in the <tt>file-rc</tt> package, please refer
6041 to the documentation of that package.
6045 These scripts are referenced by symbolic links in the
6046 <file>/etc/rc<var>n</var>.d</file> directories. When changing
6047 runlevels, <prgn>init</prgn> looks in the directory
6048 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
6049 execute, where <tt><var>n</var></tt> is the runlevel that
6050 is being changed to, or <tt>S</tt> for the boot-up
6055 The names of the links all have the form
6056 <file>S<var>mm</var><var>script</var></file> or
6057 <file>K<var>mm</var><var>script</var></file> where
6058 <var>mm</var> is a two-digit number and <var>script</var>
6059 is the name of the script (this should be the same as the
6060 name of the actual script in <file>/etc/init.d</file>).
6064 When <prgn>init</prgn> changes runlevel first the targets
6065 of the links whose names start with a <tt>K</tt> are
6066 executed, each with the single argument <tt>stop</tt>,
6067 followed by the scripts prefixed with an <tt>S</tt>, each
6068 with the single argument <tt>start</tt>. (The links are
6069 those in the <file>/etc/rc<var>n</var>.d</file> directory
6070 corresponding to the new runlevel.) The <tt>K</tt> links
6071 are responsible for killing services and the <tt>S</tt>
6072 link for starting services upon entering the runlevel.
6076 For example, if we are changing from runlevel 2 to
6077 runlevel 3, init will first execute all of the <tt>K</tt>
6078 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
6079 all of the <tt>S</tt> prefixed scripts in that directory.
6080 The links starting with <tt>K</tt> will cause the
6081 referred-to file to be executed with an argument of
6082 <tt>stop</tt>, and the <tt>S</tt> links with an argument
6087 The two-digit number <var>mm</var> is used to determine
6088 the order in which to run the scripts: low-numbered links
6089 have their scripts run first. For example, the
6090 <tt>K20</tt> scripts will be executed before the
6091 <tt>K30</tt> scripts. This is used when a certain service
6092 must be started before another. For example, the name
6093 server <prgn>bind</prgn> might need to be started before
6094 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
6095 can set up its access lists. In this case, the script
6096 that starts <prgn>bind</prgn> would have a lower number
6097 than the script that starts <prgn>inn</prgn> so that it
6099 <example compact="compact">
6106 The two runlevels 0 (halt) and 6 (reboot) are slightly
6107 different. In these runlevels, the links with an
6108 <tt>S</tt> prefix are still called after those with a
6109 <tt>K</tt> prefix, but they too are called with the single
6110 argument <tt>stop</tt>.
6114 <sect1 id="writing-init">
6115 <heading>Writing the scripts</heading>
6118 Packages that include daemons for system services should
6119 place scripts in <file>/etc/init.d</file> to start or stop
6120 services at boot time or during a change of runlevel.
6121 These scripts should be named
6122 <file>/etc/init.d/<var>package</var></file>, and they should
6123 accept one argument, saying what to do:
6126 <tag><tt>start</tt></tag>
6127 <item>start the service,</item>
6129 <tag><tt>stop</tt></tag>
6130 <item>stop the service,</item>
6132 <tag><tt>restart</tt></tag>
6133 <item>stop and restart the service if it's already running,
6134 otherwise start the service</item>
6136 <tag><tt>reload</tt></tag>
6137 <item><p>cause the configuration of the service to be
6138 reloaded without actually stopping and restarting
6141 <tag><tt>force-reload</tt></tag>
6142 <item>cause the configuration to be reloaded if the
6143 service supports this, otherwise restart the
6147 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
6148 <tt>force-reload</tt> options should be supported by all
6149 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
6154 The <file>init.d</file> scripts must ensure that they will
6155 behave sensibly (i.e., returning success and not starting
6156 multiple copies of a service) if invoked with <tt>start</tt>
6157 when the service is already running, or with <tt>stop</tt>
6158 when it isn't, and that they don't kill unfortunately-named
6159 user processes. The best way to achieve this is usually to
6160 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
6165 Be careful of using <tt>set -e</tt> in <file>init.d</file>
6166 scripts. Writing correct <file>init.d</file> scripts requires
6167 accepting various error exit statuses when daemons are already
6168 running or already stopped without aborting
6169 the <file>init.d</file> script, and common <file>init.d</file>
6170 function libraries are not safe to call with <tt>set -e</tt>
6172 <tt>/lib/lsb/init-functions</tt>, which assists in writing
6173 LSB-compliant init scripts, may fail if <tt>set -e</tt> is
6174 in effect and echoing status messages to the console fails,
6176 </footnote>. For <tt>init.d</tt> scripts, it's often easier
6177 to not use <tt>set -e</tt> and instead check the result of
6178 each command separately.
6182 If a service reloads its configuration automatically (as
6183 in the case of <prgn>cron</prgn>, for example), the
6184 <tt>reload</tt> option of the <file>init.d</file> script
6185 should behave as if the configuration has been reloaded
6190 The <file>/etc/init.d</file> scripts must be treated as
6191 configuration files, either (if they are present in the
6192 package, that is, in the .deb file) by marking them as
6193 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
6194 by managing them correctly in the maintainer scripts (see
6195 <ref id="config-files">). This is important since we want
6196 to give the local system administrator the chance to adapt
6197 the scripts to the local system, e.g., to disable a
6198 service without de-installing the package, or to specify
6199 some special command line options when starting a service,
6200 while making sure their changes aren't lost during the next
6205 These scripts should not fail obscurely when the
6206 configuration files remain but the package has been
6207 removed, as configuration files remain on the system after
6208 the package has been removed. Only when <prgn>dpkg</prgn>
6209 is executed with the <tt>--purge</tt> option will
6210 configuration files be removed. In particular, as the
6211 <file>/etc/init.d/<var>package</var></file> script itself is
6212 usually a <tt>conffile</tt>, it will remain on the system
6213 if the package is removed but not purged. Therefore, you
6214 should include a <tt>test</tt> statement at the top of the
6216 <example compact="compact">
6217 test -f <var>program-executed-later-in-script</var> || exit 0
6222 Often there are some variables in the <file>init.d</file>
6223 scripts whose values control the behavior of the scripts,
6224 and which a system administrator is likely to want to
6225 change. As the scripts themselves are frequently
6226 <tt>conffile</tt>s, modifying them requires that the
6227 administrator merge in their changes each time the package
6228 is upgraded and the <tt>conffile</tt> changes. To ease
6229 the burden on the system administrator, such configurable
6230 values should not be placed directly in the script.
6231 Instead, they should be placed in a file in
6232 <file>/etc/default</file>, which typically will have the same
6233 base name as the <file>init.d</file> script. This extra file
6234 should be sourced by the script when the script runs. It
6235 must contain only variable settings and comments in SUSv3
6236 <prgn>sh</prgn> format. It may either be a
6237 <tt>conffile</tt> or a configuration file maintained by
6238 the package maintainer scripts. See <ref id="config-files">
6243 To ensure that vital configurable values are always
6244 available, the <file>init.d</file> script should set default
6245 values for each of the shell variables it uses, either
6246 before sourcing the <file>/etc/default/</file> file or
6247 afterwards using something like the <tt>:
6248 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6249 script must behave sensibly and not fail if the
6250 <file>/etc/default</file> file is deleted.
6254 <file>/var/run</file> and <file>/var/lock</file> may be mounted
6255 as temporary filesystems<footnote>
6256 For example, using the <tt>RAMRUN</tt> and <tt>RAMLOCK</tt>
6257 options in <file>/etc/default/rcS</file>.
6258 </footnote>, so the <file>init.d</file> scripts must handle this
6259 correctly. This will typically amount to creating any required
6260 subdirectories dynamically when the <file>init.d</file> script
6261 is run, rather than including them in the package and relying on
6262 <prgn>dpkg</prgn> to create them.
6267 <heading>Interfacing with the initscript system</heading>
6270 Maintainers should use the abstraction layer provided by
6271 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6272 programs to deal with initscripts in their packages'
6273 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6274 and <prgn>postrm</prgn>.
6278 Directly managing the /etc/rc?.d links and directly
6279 invoking the <file>/etc/init.d/</file> initscripts should
6280 be done only by packages providing the initscript
6281 subsystem (such as <prgn>sysv-rc</prgn> and
6282 <prgn>file-rc</prgn>).
6286 <heading>Managing the links</heading>
6289 The program <prgn>update-rc.d</prgn> is provided for
6290 package maintainers to arrange for the proper creation and
6291 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6292 or their functional equivalent if another method is being
6293 used. This may be used by maintainers in their packages'
6294 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6298 You must not include any <file>/etc/rc<var>n</var>.d</file>
6299 symbolic links in the actual archive or manually create or
6300 remove the symbolic links in maintainer scripts; you must
6301 use the <prgn>update-rc.d</prgn> program instead. (The
6302 former will fail if an alternative method of maintaining
6303 runlevel information is being used.) You must not include
6304 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6305 in the archive either. (Only the <tt>sysvinit</tt>
6310 By default <prgn>update-rc.d</prgn> will start services in
6311 each of the multi-user state runlevels (2, 3, 4, and 5)
6312 and stop them in the halt runlevel (0), the single-user
6313 runlevel (1) and the reboot runlevel (6). The system
6314 administrator will have the opportunity to customize
6315 runlevels by simply adding, moving, or removing the
6316 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6317 symbolic links are being used, or by modifying
6318 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6323 To get the default behavior for your package, put in your
6324 <prgn>postinst</prgn> script
6325 <example compact="compact">
6326 update-rc.d <var>package</var> defaults
6328 and in your <prgn>postrm</prgn>
6329 <example compact="compact">
6330 if [ "$1" = purge ]; then
6331 update-rc.d <var>package</var> remove
6333 </example>. Note that if your package changes runlevels
6334 or priority, you may have to remove and recreate the links,
6335 since otherwise the old links may persist. Refer to the
6336 documentation of <prgn>update-rc.d</prgn>.
6340 This will use a default sequence number of 20. If it does
6341 not matter when or in which order the <file>init.d</file>
6342 script is run, use this default. If it does, then you
6343 should talk to the maintainer of the <prgn>sysvinit</prgn>
6344 package or post to <tt>debian-devel</tt>, and they will
6345 help you choose a number.
6349 For more information about using <tt>update-rc.d</tt>,
6350 please consult its man page <manref name="update-rc.d"
6356 <heading>Running initscripts</heading>
6358 The program <prgn>invoke-rc.d</prgn> is provided to make
6359 it easier for package maintainers to properly invoke an
6360 initscript, obeying runlevel and other locally-defined
6361 constraints that might limit a package's right to start,
6362 stop and otherwise manage services. This program may be
6363 used by maintainers in their packages' scripts.
6367 The package maintainer scripts must use
6368 <prgn>invoke-rc.d</prgn> to invoke the
6369 <file>/etc/init.d/*</file> initscripts, instead of
6370 calling them directly.
6374 By default, <prgn>invoke-rc.d</prgn> will pass any
6375 action requests (start, stop, reload, restart...) to the
6376 <file>/etc/init.d</file> script, filtering out requests
6377 to start or restart a service out of its intended
6382 Most packages will simply need to change:
6383 <example compact="compact">/etc/init.d/<package>
6384 <action></example> in their <prgn>postinst</prgn>
6385 and <prgn>prerm</prgn> scripts to:
6386 <example compact="compact">
6387 if which invoke-rc.d >/dev/null 2>&1; then
6388 invoke-rc.d <var>package</var> <action>
6390 /etc/init.d/<var>package</var> <action>
6396 A package should register its initscript services using
6397 <prgn>update-rc.d</prgn> before it tries to invoke them
6398 using <prgn>invoke-rc.d</prgn>. Invocation of
6399 unregistered services may fail.
6403 For more information about using
6404 <prgn>invoke-rc.d</prgn>, please consult its man page
6405 <manref name="invoke-rc.d" section="8">.
6411 <heading>Boot-time initialization</heading>
6414 There used to be another directory, <file>/etc/rc.boot</file>,
6415 which contained scripts which were run once per machine
6416 boot. This has been deprecated in favour of links from
6417 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6418 described in <ref id="/etc/init.d">. Packages must not
6419 place files in <file>/etc/rc.boot</file>.
6424 <heading>Example</heading>
6427 An example on which you can base your
6428 <file>/etc/init.d</file> scripts is found in
6429 <file>/etc/init.d/skeleton</file>.
6436 <heading>Console messages from <file>init.d</file> scripts</heading>
6439 This section describes the formats to be used for messages
6440 written to standard output by the <file>/etc/init.d</file>
6441 scripts. The intent is to improve the consistency of
6442 Debian's startup and shutdown look and feel. For this
6443 reason, please look very carefully at the details. We want
6444 the messages to have the same format in terms of wording,
6445 spaces, punctuation and case of letters.
6449 Here is a list of overall rules that should be used for
6450 messages generated by <file>/etc/init.d</file> scripts.
6456 The message should fit in one line (fewer than 80
6457 characters), start with a capital letter and end with
6458 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6462 If the script is performing some time consuming task in
6463 the background (not merely starting or stopping a
6464 program, for instance), an ellipsis (three dots:
6465 <tt>...</tt>) should be output to the screen, with no
6466 leading or tailing whitespace or line feeds.
6470 The messages should appear as if the computer is telling
6471 the user what it is doing (politely :-), but should not
6472 mention "it" directly. For example, instead of:
6473 <example compact="compact">
6474 I'm starting network daemons: nfsd mountd.
6476 the message should say
6477 <example compact="compact">
6478 Starting network daemons: nfsd mountd.
6485 <tt>init.d</tt> script should use the following standard
6486 message formats for the situations enumerated below.
6492 <p>When daemons are started</p>
6495 If the script starts one or more daemons, the output
6496 should look like this (a single line, no leading
6498 <example compact="compact">
6499 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6501 The <var>description</var> should describe the
6502 subsystem the daemon or set of daemons are part of,
6503 while <var>daemon-1</var> up to <var>daemon-n</var>
6504 denote each daemon's name (typically the file name of
6509 For example, the output of <file>/etc/init.d/lpd</file>
6511 <example compact="compact">
6512 Starting printer spooler: lpd.
6517 This can be achieved by saying
6518 <example compact="compact">
6519 echo -n "Starting printer spooler: lpd"
6520 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6523 in the script. If there are more than one daemon to
6524 start, the output should look like this:
6525 <example compact="compact">
6526 echo -n "Starting remote file system services:"
6527 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6528 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6529 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6532 This makes it possible for the user to see what is
6533 happening and when the final daemon has been started.
6534 Care should be taken in the placement of white spaces:
6535 in the example above the system administrators can
6536 easily comment out a line if they don't want to start
6537 a specific daemon, while the displayed message still
6543 <p>When a system parameter is being set</p>
6546 If you have to set up different system parameters
6547 during the system boot, you should use this format:
6548 <example compact="compact">
6549 Setting <var>parameter</var> to "<var>value</var>".
6554 You can use a statement such as the following to get
6556 <example compact="compact">
6557 echo "Setting DNS domainname to \"$domainname\"."
6562 Note that the same symbol (<tt>"</tt>) <!-- " --> is used
6563 for the left and right quotation marks. A grave accent
6564 (<tt>`</tt>) is not a quote character; neither is an
6565 apostrophe (<tt>'</tt>).
6570 <p>When a daemon is stopped or restarted</p>
6573 When you stop or restart a daemon, you should issue a
6574 message identical to the startup message, except that
6575 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6576 or <tt>Restarting</tt> respectively.
6580 For example, stopping the printer daemon will look like
6582 <example compact="compact">
6583 Stopping printer spooler: lpd.
6589 <p>When something is executed</p>
6592 There are several examples where you have to run a
6593 program at system startup or shutdown to perform a
6594 specific task, for example, setting the system's clock
6595 using <prgn>netdate</prgn> or killing all processes
6596 when the system shuts down. Your message should look
6598 <example compact="compact">
6599 Doing something very useful...done.
6601 You should print the <tt>done.</tt> immediately after
6602 the job has been completed, so that the user is
6603 informed why they have to wait. You can get this
6605 <example compact="compact">
6606 echo -n "Doing something very useful..."
6615 <p>When the configuration is reloaded</p>
6618 When a daemon is forced to reload its configuration
6619 files you should use the following format:
6620 <example compact="compact">
6621 Reloading <var>description</var> configuration...done.
6623 where <var>description</var> is the same as in the
6624 daemon starting message.
6632 <heading>Cron jobs</heading>
6635 Packages must not modify the configuration file
6636 <file>/etc/crontab</file>, and they must not modify the files in
6637 <file>/var/spool/cron/crontabs</file>.</p>
6640 If a package wants to install a job that has to be executed
6641 via cron, it should place a file with the name of the
6642 package in one or more of the following directories:
6643 <example compact="compact">
6649 As these directory names imply, the files within them are
6650 executed on an hourly, daily, weekly, or monthly basis,
6651 respectively. The exact times are listed in
6652 <file>/etc/crontab</file>.</p>
6655 All files installed in any of these directories must be
6656 scripts (e.g., shell scripts or Perl scripts) so that they
6657 can easily be modified by the local system administrator.
6658 In addition, they must be treated as configuration files.
6662 If a certain job has to be executed at some other frequency or
6663 at a specific time, the package should install a file
6664 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6665 same syntax as <file>/etc/crontab</file> and is processed by
6666 <prgn>cron</prgn> automatically. The file must also be
6667 treated as a configuration file. (Note that entries in the
6668 <file>/etc/cron.d</file> directory are not handled by
6669 <prgn>anacron</prgn>. Thus, you should only use this
6670 directory for jobs which may be skipped if the system is not
6673 Unlike <file>crontab</file> files described in the IEEE Std
6674 1003.1-2008 (POSIX.1) available from
6675 <url id="http://www.opengroup.org/onlinepubs/9699919799/"
6676 name="The Open Group">, the files in
6677 <file>/etc/cron.d</file> and the file
6678 <file>/etc/crontab</file> have seven fields; namely:
6680 <item>Minute [0,59]</item>
6681 <item>Hour [0,23]</item>
6682 <item>Day of the month [1,31]</item>
6683 <item>Month of the year [1,12]</item>
6684 <item>Day of the week ([0,6] with 0=Sunday)</item>
6685 <item>Username</item>
6686 <item>Command to be run</item>
6688 Ranges of numbers are allowed. Ranges are two numbers
6689 separated with a hyphen. The specified range is inclusive.
6690 Lists are allowed. A list is a set of numbers (or ranges)
6691 separated by commas. Step values can be used in conjunction
6696 The scripts or <tt>crontab</tt> entries in these directories should
6697 check if all necessary programs are installed before they
6698 try to execute them. Otherwise, problems will arise when a
6699 package was removed but not purged since configuration files
6700 are kept on the system in this situation.
6704 Any <tt>cron</tt> daemon must provide
6705 <file>/usr/bin/crontab</file> and support normal
6706 <tt>crontab</tt> entries as specified in POSIX. The daemon
6707 must also support names for days and months, ranges, and
6708 step values. It has to support <file>/etc/crontab</file>,
6709 and correctly execute the scripts in
6710 <file>/etc/cron.d</file>. The daemon must also correctly
6712 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>.
6717 <heading>Menus</heading>
6720 The Debian <tt>menu</tt> package provides a standard
6721 interface between packages providing applications and
6722 <em>menu programs</em> (either X window managers or
6723 text-based menu programs such as <prgn>pdmenu</prgn>).
6727 All packages that provide applications that need not be
6728 passed any special command line arguments for normal
6729 operation should register a menu entry for those
6730 applications, so that users of the <tt>menu</tt> package
6731 will automatically get menu entries in their window
6732 managers, as well in shells like <tt>pdmenu</tt>.
6736 Menu entries should follow the current menu policy.
6740 The menu policy can be found in the <tt>menu-policy</tt>
6741 files in the <tt>debian-policy</tt> package.
6742 It is also available from the Debian web mirrors at
6743 <tt><url name="/doc/packaging-manuals/menu-policy/"
6744 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6748 Please also refer to the <em>Debian Menu System</em>
6749 documentation that comes with the <package>menu</package>
6750 package for information about how to register your
6756 <heading>Multimedia handlers</heading>
6759 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6760 is a mechanism for encoding files and data streams and
6761 providing meta-information about them, in particular their
6762 type (e.g. audio or video) and format (e.g. PNG, HTML,
6767 Registration of MIME type handlers allows programs like mail
6768 user agents and web browsers to invoke these handlers to
6769 view, edit or display MIME types they don't support directly.
6773 Packages which provide the ability to view/show/play,
6774 compose, edit or print MIME types should register themselves
6775 as such following the current MIME support policy.
6779 The MIME support policy can be found in the <tt>mime-policy</tt>
6780 files in the <tt>debian-policy</tt> package.
6781 It is also available from the Debian web mirrors at
6782 <tt><url name="/doc/packaging-manuals/mime-policy/"
6783 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6789 <heading>Keyboard configuration</heading>
6792 To achieve a consistent keyboard configuration so that all
6793 applications interpret a keyboard event the same way, all
6794 programs in the Debian distribution must be configured to
6795 comply with the following guidelines.
6799 The following keys must have the specified interpretations:
6802 <tag><tt><--</tt></tag>
6803 <item>delete the character to the left of the cursor</item>
6805 <tag><tt>Delete</tt></tag>
6806 <item>delete the character to the right of the cursor</item>
6808 <tag><tt>Control+H</tt></tag>
6809 <item>emacs: the help prefix</item>
6812 The interpretation of any keyboard events should be
6813 independent of the terminal that is used, be it a virtual
6814 console, an X terminal emulator, an rlogin/telnet session,
6819 The following list explains how the different programs
6820 should be set up to achieve this:
6826 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6830 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6834 X translations are set up to make
6835 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6836 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6837 is the vt220 escape code for the "delete character"
6838 key). This must be done by loading the X resources
6839 using <prgn>xrdb</prgn> on all local X displays, not
6840 using the application defaults, so that the
6841 translation resources used correspond to the
6842 <prgn>xmodmap</prgn> settings.
6846 The Linux console is configured to make
6847 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6848 generate <tt>ESC [ 3 ~</tt>.
6852 X applications are configured so that <tt><</tt>
6853 deletes left, and <tt>Delete</tt> deletes right. Motif
6854 applications already work like this.
6858 Terminals should have <tt>stty erase ^?</tt> .
6862 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6863 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6864 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6868 Emacs is programmed to map <tt>KB_Backspace</tt> or
6869 the <tt>stty erase</tt> character to
6870 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6871 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6872 <tt>^H</tt> to <tt>help</tt> as always.
6876 Other applications use the <tt>stty erase</tt>
6877 character and <tt>kdch1</tt> for the two delete keys,
6878 with ASCII DEL being "delete previous character" and
6879 <tt>kdch1</tt> being "delete character under
6887 This will solve the problem except for the following
6894 Some terminals have a <tt><--</tt> key that cannot
6895 be made to produce anything except <tt>^H</tt>. On
6896 these terminals Emacs help will be unavailable on
6897 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6898 character takes precedence in Emacs, and has been set
6899 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6900 available) can be used instead.
6904 Some operating systems use <tt>^H</tt> for <tt>stty
6905 erase</tt>. However, modern telnet versions and all
6906 rlogin versions propagate <tt>stty</tt> settings, and
6907 almost all UNIX versions honour <tt>stty erase</tt>.
6908 Where the <tt>stty</tt> settings are not propagated
6909 correctly, things can be made to work by using
6910 <tt>stty</tt> manually.
6914 Some systems (including previous Debian versions) use
6915 <prgn>xmodmap</prgn> to arrange for both
6916 <tt><--</tt> and <tt>Delete</tt> to generate
6917 <tt>KB_Delete</tt>. We can change the behavior of
6918 their X clients using the same X resources that we use
6919 to do it for our own clients, or configure our clients
6920 using their resources when things are the other way
6921 around. On displays configured like this
6922 <tt>Delete</tt> will not work, but <tt><--</tt>
6927 Some operating systems have different <tt>kdch1</tt>
6928 settings in their <tt>terminfo</tt> database for
6929 <tt>xterm</tt> and others. On these systems the
6930 <tt>Delete</tt> key will not work correctly when you
6931 log in from a system conforming to our policy, but
6932 <tt><--</tt> will.
6939 <heading>Environment variables</heading>
6942 A program must not depend on environment variables to get
6943 reasonable defaults. (That's because these environment
6944 variables would have to be set in a system-wide
6945 configuration file like <file>/etc/profile</file>, which is not
6946 supported by all shells.)
6950 If a program usually depends on environment variables for its
6951 configuration, the program should be changed to fall back to
6952 a reasonable default configuration if these environment
6953 variables are not present. If this cannot be done easily
6954 (e.g., if the source code of a non-free program is not
6955 available), the program must be replaced by a small
6956 "wrapper" shell script which sets the environment variables
6957 if they are not already defined, and calls the original program.
6961 Here is an example of a wrapper script for this purpose:
6963 <example compact="compact">
6965 BAR=${BAR:-/var/lib/fubar}
6967 exec /usr/lib/foo/foo "$@"
6972 Furthermore, as <file>/etc/profile</file> is a configuration
6973 file of the <prgn>base-files</prgn> package, other packages must
6974 not put any environment variables or other commands into that
6979 <sect id="doc-base">
6980 <heading>Registering Documents using doc-base</heading>
6983 The <package>doc-base</package> package implements a
6984 flexible mechanism for handling and presenting
6985 documentation. The recommended practice is for every Debian
6986 package that provides online documentation (other than just
6987 manual pages) to register these documents with
6988 <package>doc-base</package> by installing a
6989 <package>doc-base</package> control file via the
6990 <prgn/install-docs/ script at installation time and
6991 de-register the manuals again when the package is removed.
6994 Please refer to the documentation that comes with the
6995 <package>doc-base</package> package for information and
7004 <heading>Files</heading>
7007 <heading>Binaries</heading>
7010 Two different packages must not install programs with
7011 different functionality but with the same filenames. (The
7012 case of two programs having the same functionality but
7013 different implementations is handled via "alternatives" or
7014 the "Conflicts" mechanism. See <ref id="maintscripts"> and
7015 <ref id="conflicts"> respectively.) If this case happens,
7016 one of the programs must be renamed. The maintainers should
7017 report this to the <tt>debian-devel</tt> mailing list and
7018 try to find a consensus about which program will have to be
7019 renamed. If a consensus cannot be reached, <em>both</em>
7020 programs must be renamed.
7024 By default, when a package is being built, any binaries
7025 created should include debugging information, as well as
7026 being compiled with optimization. You should also turn on
7027 as many reasonable compilation warnings as possible; this
7028 makes life easier for porters, who can then look at build
7029 logs for possible problems. For the C programming language,
7030 this means the following compilation parameters should be
7032 <example compact="compact">
7034 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
7036 INSTALL = install -s # (or use strip on the files in debian/tmp)
7041 Note that by default all installed binaries should be stripped,
7042 either by using the <tt>-s</tt> flag to
7043 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
7044 the binaries after they have been copied into
7045 <file>debian/tmp</file> but before the tree is made into a
7050 Although binaries in the build tree should be compiled with
7051 debugging information by default, it can often be difficult to
7052 debug programs if they are also subjected to compiler
7053 optimization. For this reason, it is recommended to support the
7054 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
7055 (see <ref id="debianrules-options">). This variable can contain
7056 several flags to change how a package is compiled and built.
7060 It is up to the package maintainer to decide what
7061 compilation options are best for the package. Certain
7062 binaries (such as computationally-intensive programs) will
7063 function better with certain flags (<tt>-O3</tt>, for
7064 example); feel free to use them. Please use good judgment
7065 here. Don't use flags for the sake of it; only use them
7066 if there is good reason to do so. Feel free to override
7067 the upstream author's ideas about which compilation
7068 options are best: they are often inappropriate for our
7074 <sect id="libraries">
7075 <heading>Libraries</heading>
7078 If the package is <strong>architecture: any</strong>, then
7079 the shared library compilation and linking flags must have
7080 <tt>-fPIC</tt>, or the package shall not build on some of
7081 the supported architectures<footnote>
7083 If you are using GCC, <tt>-fPIC</tt> produces code with
7084 relocatable position independent code, which is required for
7085 most architectures to create a shared library, with i386 and
7086 perhaps some others where non position independent code is
7087 permitted in a shared library.
7090 Position independent code may have a performance penalty,
7091 especially on <tt>i386</tt>. However, in most cases the
7092 speed penalty must be measured against the memory wasted on
7093 the few architectures where non position independent code is
7096 </footnote>. Any exception to this rule must be discussed on
7097 the mailing list <em>debian-devel@lists.debian.org</em>, and
7098 a rough consensus obtained. The reasons for not compiling
7099 with <tt>-fPIC</tt> flag must be recorded in the file
7100 <tt>README.Debian</tt>, and care must be taken to either
7101 restrict the architecture or arrange for <tt>-fPIC</tt> to
7102 be used on architectures where it is required.<footnote>
7104 Some of the reasons why this might be required is if the
7105 library contains hand crafted assembly code that is not
7106 relocatable, the speed penalty is excessive for compute
7107 intensive libs, and similar reasons.
7112 As to the static libraries, the common case is not to have
7113 relocatable code, since there is no benefit, unless in specific
7114 cases; therefore the static version must not be compiled
7115 with the <tt>-fPIC</tt> flag. Any exception to this rule
7116 should be discussed on the mailing list
7117 <em>debian-devel@lists.debian.org</em>, and the reasons for
7118 compiling with the <tt>-fPIC</tt> flag must be recorded in
7119 the file <tt>README.Debian</tt>. <footnote>
7121 Some of the reasons for linking static libraries with
7122 the <tt>-fPIC</tt> flag are if, for example, one needs a
7123 Perl API for a library that is under rapid development,
7124 and has an unstable API, so shared libraries are
7125 pointless at this phase of the library's development. In
7126 that case, since Perl needs a library with relocatable
7127 code, it may make sense to create a static library with
7128 relocatable code. Another reason cited is if you are
7129 distilling various libraries into a common shared
7130 library, like <tt>mklibs</tt> does in the Debian
7136 In other words, if both a shared and a static library is
7137 being built, each source unit (<tt>*.c</tt>, for example,
7138 for C files) will need to be compiled twice, for the normal
7142 You must specify the gcc option <tt>-D_REENTRANT</tt>
7143 when building a library (either static or shared) to make
7144 the library compatible with LinuxThreads.
7148 Although not enforced by the build tools, shared libraries
7149 must be linked against all libraries that they use symbols from
7150 in the same way that binaries are. This ensures the correct
7151 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
7152 system and guarantees that all libraries can be safely opened
7153 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
7154 option <tt>-Wl,-z,defs</tt> when building a shared library.
7155 Since this option enforces symbol resolution at build time,
7156 a missing library reference will be caught early as a fatal
7161 All installed shared libraries should be stripped with
7162 <example compact="compact">
7163 strip --strip-unneeded <var>your-lib</var>
7165 (The option <tt>--strip-unneeded</tt> makes
7166 <prgn>strip</prgn> remove only the symbols which aren't
7167 needed for relocation processing.) Shared libraries can
7168 function perfectly well when stripped, since the symbols for
7169 dynamic linking are in a separate part of the ELF object
7171 You might also want to use the options
7172 <tt>--remove-section=.comment</tt> and
7173 <tt>--remove-section=.note</tt> on both shared libraries
7174 and executables, and <tt>--strip-debug</tt> on static
7180 Note that under some circumstances it may be useful to
7181 install a shared library unstripped, for example when
7182 building a separate package to support debugging.
7186 Shared object files (often <file>.so</file> files) that are not
7187 public libraries, that is, they are not meant to be linked
7188 to by third party executables (binaries of other packages),
7189 should be installed in subdirectories of the
7190 <file>/usr/lib</file> directory. Such files are exempt from the
7191 rules that govern ordinary shared libraries, except that
7192 they must not be installed executable and should be
7194 A common example are the so-called "plug-ins",
7195 internal shared objects that are dynamically loaded by
7196 programs using <manref name="dlopen" section="3">.
7201 An ever increasing number of packages are using
7202 <prgn>libtool</prgn> to do their linking. The latest GNU
7203 libtools (>= 1.3a) can take advantage of the metadata in the
7204 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
7205 files). The main advantage of <prgn>libtool</prgn>'s
7206 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
7207 store and subsequently access metadata with respect to the
7208 libraries it builds. <prgn>libtool</prgn> will search for
7209 those files, which contain a lot of useful information about
7210 a library (such as library dependency information for static
7211 linking). Also, they're <em>essential</em> for programs
7212 using <tt>libltdl</tt>.<footnote>
7213 Although <prgn>libtool</prgn> is fully capable of
7214 linking against shared libraries which don't have
7215 <tt>.la</tt> files, as it is a mere shell script it can
7216 add considerably to the build time of a
7217 <prgn>libtool</prgn>-using package if that shell script
7218 has to derive all this information from first principles
7219 for each library every time it is linked. With the
7220 advent of <prgn>libtool</prgn> version 1.4 (and to a
7221 lesser extent <prgn>libtool</prgn> version 1.3), the
7222 <file>.la</file> files also store information about
7223 inter-library dependencies which cannot necessarily be
7224 derived after the <file>.la</file> file is deleted.
7229 Packages that use <prgn>libtool</prgn> to create shared
7230 libraries should include the <file>.la</file> files in the
7231 <tt>-dev</tt> package, unless the package relies on
7232 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
7233 the <tt>.la</tt> files must go in the run-time library
7238 You must make sure that you use only released versions of
7239 shared libraries to build your packages; otherwise other
7240 users will not be able to run your binaries
7241 properly. Producing source packages that depend on
7242 unreleased compilers is also usually a bad
7249 <heading>Shared libraries</heading>
7251 This section has moved to <ref id="sharedlibs">.
7257 <heading>Scripts</heading>
7260 All command scripts, including the package maintainer
7261 scripts inside the package and used by <prgn>dpkg</prgn>,
7262 should have a <tt>#!</tt> line naming the shell to be used
7267 In the case of Perl scripts this should be
7268 <tt>#!/usr/bin/perl</tt>.
7272 When scripts are installed into a directory in the system
7273 PATH, the script name should not include an extension such
7274 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7275 language currently used to implement it.
7278 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>) other than
7279 <file>init.d</file> scripts should almost certainly start
7280 with <tt>set -e</tt> so that errors are detected.
7281 <file>init.d</file> scripts are something of a special case, due
7282 to how frequently they need to call commands that are allowed to
7283 fail, and it may instead be easier to check the exit status of
7284 commands directly. See <ref id="writing-init"> for more
7285 information about writing <file>init.d</file> scripts.
7288 Every script should use <tt>set -e</tt> or check the exit status
7289 of <em>every</em> command.
7292 Scripts may assume that <file>/bin/sh</file> implements the
7293 SUSv3 Shell Command Language<footnote>
7294 Single UNIX Specification, version 3, which is also IEEE
7295 1003.1-2004 (POSIX), and is available on the World Wide Web
7296 from <url id="http://www.unix.org/version3/online.html"
7297 name="The Open Group"> after free
7298 registration.</footnote>
7299 plus the following additional features not mandated by
7301 These features are in widespread use in the Linux community
7302 and are implemented in all of bash, dash, and ksh, the most
7303 common shells users may wish to use as <file>/bin/sh</file>.
7306 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7307 must not generate a newline.</item>
7308 <item><tt>test</tt>, if implemented as a shell built-in, must
7309 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7311 <item><tt>local</tt> to create a scoped variable must be
7312 supported, including listing multiple variables in a single
7313 local command and assigning a value to a variable at the
7314 same time as localizing it. <tt>local</tt> may or
7315 may not preserve the variable value from an outer scope if
7316 no assignment is present. Uses such as:
7320 # ... use a, b, c, d ...
7323 must be supported and must set the value of <tt>c</tt> to
7327 If a shell script requires non-SUSv3 features from the shell
7328 interpreter other than those listed above, the appropriate shell
7329 must be specified in the first line of the script (e.g.,
7330 <tt>#!/bin/bash</tt>) and the package must depend on the package
7331 providing the shell (unless the shell package is marked
7332 "Essential", as in the case of <prgn>bash</prgn>).
7336 You may wish to restrict your script to SUSv3 features plus the
7337 above set when possible so that it may use <file>/bin/sh</file>
7338 as its interpreter. If your script works with <prgn>dash</prgn>
7339 (originally called <prgn>ash</prgn>), it probably complies with
7340 the above requirements, but if you are in doubt, use
7341 <file>/bin/bash</file>.
7345 Perl scripts should check for errors when making any
7346 system calls, including <tt>open</tt>, <tt>print</tt>,
7347 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7351 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7352 scripting languages. See <em>Csh Programming Considered
7353 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7354 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7355 If an upstream package comes with <prgn>csh</prgn> scripts
7356 then you must make sure that they start with
7357 <tt>#!/bin/csh</tt> and make your package depend on the
7358 <prgn>c-shell</prgn> virtual package.
7362 Any scripts which create files in world-writeable
7363 directories (e.g., in <file>/tmp</file>) must use a
7364 mechanism which will fail atomically if a file with the same
7365 name already exists.
7369 The Debian base system provides the <prgn>tempfile</prgn>
7370 and <prgn>mktemp</prgn> utilities for use by scripts for
7377 <heading>Symbolic links</heading>
7380 In general, symbolic links within a top-level directory
7381 should be relative, and symbolic links pointing from one
7382 top-level directory into another should be absolute. (A
7383 top-level directory is a sub-directory of the root
7384 directory <file>/</file>.)
7388 In addition, symbolic links should be specified as short as
7389 possible, i.e., link targets like <file>foo/../bar</file> are
7394 Note that when creating a relative link using
7395 <prgn>ln</prgn> it is not necessary for the target of the
7396 link to exist relative to the working directory you're
7397 running <prgn>ln</prgn> from, nor is it necessary to change
7398 directory to the directory where the link is to be made.
7399 Simply include the string that should appear as the target
7400 of the link (this will be a pathname relative to the
7401 directory in which the link resides) as the first argument
7406 For example, in your <prgn>Makefile</prgn> or
7407 <file>debian/rules</file>, you can do things like:
7408 <example compact="compact">
7409 ln -fs gcc $(prefix)/bin/cc
7410 ln -fs gcc debian/tmp/usr/bin/cc
7411 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7412 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7417 A symbolic link pointing to a compressed file should always
7418 have the same file extension as the referenced file. (For
7419 example, if a file <file>foo.gz</file> is referenced by a
7420 symbolic link, the filename of the link has to end with
7421 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7426 <heading>Device files</heading>
7429 Packages must not include device files or named pipes in the
7434 If a package needs any special device files that are not
7435 included in the base system, it must call
7436 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7437 after notifying the user<footnote>
7438 This notification could be done via a (low-priority)
7439 debconf message, or an echo (printf) statement.
7444 Packages must not remove any device files in the
7445 <prgn>postrm</prgn> or any other script. This is left to the
7446 system administrator.
7450 Debian uses the serial devices
7451 <file>/dev/ttyS*</file>. Programs using the old
7452 <file>/dev/cu*</file> devices should be changed to use
7453 <file>/dev/ttyS*</file>.
7457 Named pipes needed by the package must be created in
7458 the <prgn>postinst</prgn> script<footnote>
7459 It's better to use <prgn>mkfifo</prgn> rather
7460 than <prgn>mknod</prgn> to create named pipes so that
7461 automated checks for packages incorrectly creating device
7462 files with <prgn>mknod</prgn> won't have false positives.
7463 </footnote> and removed in
7464 the <prgn>prerm</prgn> or <prgn>postrm</prgn> script as
7469 <sect id="config-files">
7470 <heading>Configuration files</heading>
7473 <heading>Definitions</heading>
7477 <tag>configuration file</tag>
7479 A file that affects the operation of a program, or
7480 provides site- or host-specific information, or
7481 otherwise customizes the behavior of a program.
7482 Typically, configuration files are intended to be
7483 modified by the system administrator (if needed or
7484 desired) to conform to local policy or to provide
7485 more useful site-specific behavior.
7488 <tag><tt>conffile</tt></tag>
7490 A file listed in a package's <tt>conffiles</tt>
7491 file, and is treated specially by <prgn>dpkg</prgn>
7492 (see <ref id="configdetails">).
7498 The distinction between these two is important; they are
7499 not interchangeable concepts. Almost all
7500 <tt>conffile</tt>s are configuration files, but many
7501 configuration files are not <tt>conffiles</tt>.
7505 As noted elsewhere, <file>/etc/init.d</file> scripts,
7506 <file>/etc/default</file> files, scripts installed in
7507 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7508 configuration installed in <file>/etc/cron.d</file> must be
7509 treated as configuration files. In general, any script that
7510 embeds configuration information is de-facto a configuration
7511 file and should be treated as such.
7516 <heading>Location</heading>
7519 Any configuration files created or used by your package
7520 must reside in <file>/etc</file>. If there are several,
7521 consider creating a subdirectory of <file>/etc</file>
7522 named after your package.
7526 If your package creates or uses configuration files
7527 outside of <file>/etc</file>, and it is not feasible to modify
7528 the package to use <file>/etc</file> directly, put the files
7529 in <file>/etc</file> and create symbolic links to those files
7530 from the location that the package requires.
7535 <heading>Behavior</heading>
7538 Configuration file handling must conform to the following
7540 <list compact="compact">
7542 local changes must be preserved during a package
7546 configuration files must be preserved when the
7547 package is removed, and only deleted when the
7551 Obsolete configuration files without local changes may be
7552 removed by the package during upgrade.
7556 The easy way to achieve this behavior is to make the
7557 configuration file a <tt>conffile</tt>. This is
7558 appropriate only if it is possible to distribute a default
7559 version that will work for most installations, although
7560 some system administrators may choose to modify it. This
7561 implies that the default version will be part of the
7562 package distribution, and must not be modified by the
7563 maintainer scripts during installation (or at any other
7568 In order to ensure that local changes are preserved
7569 correctly, no package may contain or make hard links to
7570 conffiles.<footnote>
7571 Rationale: There are two problems with hard links.
7572 The first is that some editors break the link while
7573 editing one of the files, so that the two files may
7574 unwittingly become unlinked and different. The second
7575 is that <prgn>dpkg</prgn> might break the hard link
7576 while upgrading <tt>conffile</tt>s.
7581 The other way to do it is via the maintainer scripts. In
7582 this case, the configuration file must not be listed as a
7583 <tt>conffile</tt> and must not be part of the package
7584 distribution. If the existence of a file is required for
7585 the package to be sensibly configured it is the
7586 responsibility of the package maintainer to provide
7587 maintainer scripts which correctly create, update and
7588 maintain the file and remove it on purge. (See <ref
7589 id="maintainerscripts"> for more information.) These
7590 scripts must be idempotent (i.e., must work correctly if
7591 <prgn>dpkg</prgn> needs to re-run them due to errors
7592 during installation or removal), must cope with all the
7593 variety of ways <prgn>dpkg</prgn> can call maintainer
7594 scripts, must not overwrite or otherwise mangle the user's
7595 configuration without asking, must not ask unnecessary
7596 questions (particularly during upgrades), and must
7597 otherwise be good citizens.
7601 The scripts are not required to configure every possible
7602 option for the package, but only those necessary to get
7603 the package running on a given system. Ideally the
7604 sysadmin should not have to do any configuration other
7605 than that done (semi-)automatically by the
7606 <prgn>postinst</prgn> script.
7610 A common practice is to create a script called
7611 <file><var>package</var>-configure</file> and have the
7612 package's <prgn>postinst</prgn> call it if and only if the
7613 configuration file does not already exist. In certain
7614 cases it is useful for there to be an example or template
7615 file which the maintainer scripts use. Such files should
7616 be in <file>/usr/share/<var>package</var></file> or
7617 <file>/usr/lib/<var>package</var></file> (depending on whether
7618 they are architecture-independent or not). There should
7619 be symbolic links to them from
7620 <file>/usr/share/doc/<var>package</var>/examples</file> if
7621 they are examples, and should be perfectly ordinary
7622 <prgn>dpkg</prgn>-handled files (<em>not</em>
7623 configuration files).
7627 These two styles of configuration file handling must
7628 not be mixed, for that way lies madness:
7629 <prgn>dpkg</prgn> will ask about overwriting the file
7630 every time the package is upgraded.
7635 <heading>Sharing configuration files</heading>
7638 Packages which specify the same file as a
7639 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7640 with each other. (This is an instance of the general rule
7641 about not sharing files. Note that neither alternatives
7642 nor diversions are likely to be appropriate in this case;
7643 in particular, <prgn>dpkg</prgn> does not handle diverted
7644 <tt>conffile</tt>s well.)
7648 The maintainer scripts must not alter a <tt>conffile</tt>
7649 of <em>any</em> package, including the one the scripts
7654 If two or more packages use the same configuration file
7655 and it is reasonable for both to be installed at the same
7656 time, one of these packages must be defined as
7657 <em>owner</em> of the configuration file, i.e., it will be
7658 the package which handles that file as a configuration
7659 file. Other packages that use the configuration file must
7660 depend on the owning package if they require the
7661 configuration file to operate. If the other package will
7662 use the configuration file if present, but is capable of
7663 operating without it, no dependency need be declared.
7667 If it is desirable for two or more related packages to
7668 share a configuration file <em>and</em> for all of the
7669 related packages to be able to modify that configuration
7670 file, then the following should be done:
7671 <enumlist compact="compact">
7673 One of the related packages (the "owning" package)
7674 will manage the configuration file with maintainer
7675 scripts as described in the previous section.
7678 The owning package should also provide a program
7679 that the other packages may use to modify the
7683 The related packages must use the provided program
7684 to make any desired modifications to the
7685 configuration file. They should either depend on
7686 the core package to guarantee that the configuration
7687 modifier program is available or accept gracefully
7688 that they cannot modify the configuration file if it
7689 is not. (This is in addition to the fact that the
7690 configuration file may not even be present in the
7697 Sometimes it's appropriate to create a new package which
7698 provides the basic infrastructure for the other packages
7699 and which manages the shared configuration files. (The
7700 <tt>sgml-base</tt> package is a good example.)
7705 <heading>User configuration files ("dotfiles")</heading>
7708 The files in <file>/etc/skel</file> will automatically be
7709 copied into new user accounts by <prgn>adduser</prgn>.
7710 No other program should reference the files in
7711 <file>/etc/skel</file>.
7715 Therefore, if a program needs a dotfile to exist in
7716 advance in <file>$HOME</file> to work sensibly, that dotfile
7717 should be installed in <file>/etc/skel</file> and treated as a
7722 However, programs that require dotfiles in order to
7723 operate sensibly are a bad thing, unless they do create
7724 the dotfiles themselves automatically.
7728 Furthermore, programs should be configured by the Debian
7729 default installation to behave as closely to the upstream
7730 default behavior as possible.
7734 Therefore, if a program in a Debian package needs to be
7735 configured in some way in order to operate sensibly, that
7736 should be done using a site-wide configuration file placed
7737 in <file>/etc</file>. Only if the program doesn't support a
7738 site-wide default configuration and the package maintainer
7739 doesn't have time to add it may a default per-user file be
7740 placed in <file>/etc/skel</file>.
7744 <file>/etc/skel</file> should be as empty as we can make it.
7745 This is particularly true because there is no easy (or
7746 necessarily desirable) mechanism for ensuring that the
7747 appropriate dotfiles are copied into the accounts of
7748 existing users when a package is installed.
7754 <heading>Log files</heading>
7756 Log files should usually be named
7757 <file>/var/log/<var>package</var>.log</file>. If you have many
7758 log files, or need a separate directory for permission
7759 reasons (<file>/var/log</file> is writable only by
7760 <file>root</file>), you should usually create a directory named
7761 <file>/var/log/<var>package</var></file> and place your log
7766 Log files must be rotated occasionally so that they don't
7767 grow indefinitely; the best way to do this is to drop a log
7768 rotation configuration file into the directory
7769 <file>/etc/logrotate.d</file> and use the facilities provided by
7770 logrotate.<footnote>
7772 The traditional approach to log files has been to set up
7773 <em>ad hoc</em> log rotation schemes using simple shell
7774 scripts and cron. While this approach is highly
7775 customizable, it requires quite a lot of sysadmin work.
7776 Even though the original Debian system helped a little
7777 by automatically installing a system which can be used
7778 as a template, this was deemed not enough.
7782 The use of <prgn>logrotate</prgn>, a program developed
7783 by Red Hat, is better, as it centralizes log management.
7784 It has both a configuration file
7785 (<file>/etc/logrotate.conf</file>) and a directory where
7786 packages can drop their individual log rotation
7787 configurations (<file>/etc/logrotate.d</file>).
7790 Here is a good example for a logrotate config
7791 file (for more information see <manref name="logrotate"
7793 <example compact="compact">
7794 /var/log/foo/*.log {
7799 /etc/init.d/foo force-reload
7803 This rotates all files under <file>/var/log/foo</file>, saves 12
7804 compressed generations, and forces the daemon to reload its
7805 configuration information after the log rotation.
7809 Log files should be removed when the package is
7810 purged (but not when it is only removed). This should be
7811 done by the <prgn>postrm</prgn> script when it is called
7812 with the argument <tt>purge</tt> (see <ref
7813 id="removedetails">).
7818 <heading>Permissions and owners</heading>
7821 The rules in this section are guidelines for general use.
7822 If necessary you may deviate from the details below.
7823 However, if you do so you must make sure that what is done
7824 is secure and you should try to be as consistent as possible
7825 with the rest of the system. You should probably also
7826 discuss it on <prgn>debian-devel</prgn> first.
7830 Files should be owned by <tt>root:root</tt>, and made
7831 writable only by the owner and universally readable (and
7832 executable, if appropriate), that is mode 644 or 755.
7836 Directories should be mode 755 or (for group-writability)
7837 mode 2775. The ownership of the directory should be
7838 consistent with its mode: if a directory is mode 2775, it
7839 should be owned by the group that needs write access to
7842 When a package is upgraded, and the owner or permissions
7843 of a file included in the package has changed, dpkg
7844 arranges for the ownership and permissions to be
7845 correctly set upon installation. However, this does not
7846 extend to directories; the permissions and ownership of
7847 directories already on the system does not change on
7848 install or upgrade of packages. This makes sense, since
7849 otherwise common directories like <tt>/usr</tt> would
7850 always be in flux. To correctly change permissions of a
7851 directory the package owns, explicit action is required,
7852 usually in the <tt>postinst</tt> script. Care must be
7853 taken to handle downgrades as well, in that case.
7860 Setuid and setgid executables should be mode 4755 or 2755
7861 respectively, and owned by the appropriate user or group.
7862 They should not be made unreadable (modes like 4711 or
7863 2711 or even 4111); doing so achieves no extra security,
7864 because anyone can find the binary in the freely available
7865 Debian package; it is merely inconvenient. For the same
7866 reason you should not restrict read or execute permissions
7867 on non-set-id executables.
7871 Some setuid programs need to be restricted to particular
7872 sets of users, using file permissions. In this case they
7873 should be owned by the uid to which they are set-id, and by
7874 the group which should be allowed to execute them. They
7875 should have mode 4754; again there is no point in making
7876 them unreadable to those users who must not be allowed to
7881 It is possible to arrange that the system administrator can
7882 reconfigure the package to correspond to their local
7883 security policy by changing the permissions on a binary:
7884 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7885 described below.<footnote>
7886 Ordinary files installed by <prgn>dpkg</prgn> (as
7887 opposed to <tt>conffile</tt>s and other similar objects)
7888 normally have their permissions reset to the distributed
7889 permissions when the package is reinstalled. However,
7890 the use of <prgn>dpkg-statoverride</prgn> overrides this
7893 Another method you should consider is to create a group for
7894 people allowed to use the program(s) and make any setuid
7895 executables executable only by that group.
7899 If you need to create a new user or group for your package
7900 there are two possibilities. Firstly, you may need to
7901 make some files in the binary package be owned by this
7902 user or group, or you may need to compile the user or
7903 group id (rather than just the name) into the binary
7904 (though this latter should be avoided if possible, as in
7905 this case you need a statically allocated id).</p>
7908 If you need a statically allocated id, you must ask for a
7909 user or group id from the <tt>base-passwd</tt> maintainer,
7910 and must not release the package until you have been
7911 allocated one. Once you have been allocated one you must
7912 either make the package depend on a version of the
7913 <tt>base-passwd</tt> package with the id present in
7914 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7915 your package to create the user or group itself with the
7916 correct id (using <tt>adduser</tt>) in its
7917 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7918 the <prgn>postinst</prgn> is to be preferred if it is
7919 possible, otherwise a pre-dependency will be needed on the
7920 <tt>adduser</tt> package.)
7924 On the other hand, the program might be able to determine
7925 the uid or gid from the user or group name at runtime, so
7926 that a dynamically allocated id can be used. In this case
7927 you should choose an appropriate user or group name,
7928 discussing this on <prgn>debian-devel</prgn> and checking
7929 with the <package/base-passwd/ maintainer that it is unique and that
7930 they do not wish you to use a statically allocated id
7931 instead. When this has been checked you must arrange for
7932 your package to create the user or group if necessary using
7933 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7934 <prgn>postinst</prgn> script (again, the latter is to be
7935 preferred if it is possible).
7939 Note that changing the numeric value of an id associated
7940 with a name is very difficult, and involves searching the
7941 file system for all appropriate files. You need to think
7942 carefully whether a static or dynamic id is required, since
7943 changing your mind later will cause problems.
7946 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7948 This section is not intended as policy, but as a
7949 description of the use of <prgn>dpkg-statoverride</prgn>.
7953 If a system administrator wishes to have a file (or
7954 directory or other such thing) installed with owner and
7955 permissions different from those in the distributed Debian
7956 package, they can use the <prgn>dpkg-statoverride</prgn>
7957 program to instruct <prgn>dpkg</prgn> to use the different
7958 settings every time the file is installed. Thus the
7959 package maintainer should distribute the files with their
7960 normal permissions, and leave it for the system
7961 administrator to make any desired changes. For example, a
7962 daemon which is normally required to be setuid root, but
7963 in certain situations could be used without being setuid,
7964 should be installed setuid in the <tt>.deb</tt>. Then the
7965 local system administrator can change this if they wish.
7966 If there are two standard ways of doing it, the package
7967 maintainer can use <tt>debconf</tt> to find out the
7968 preference, and call <prgn>dpkg-statoverride</prgn> in the
7969 maintainer script if necessary to accommodate the system
7970 administrator's choice. Care must be taken during
7971 upgrades to not override an existing setting.
7975 Given the above, <prgn>dpkg-statoverride</prgn> is
7976 essentially a tool for system administrators and would not
7977 normally be needed in the maintainer scripts. There is
7978 one type of situation, though, where calls to
7979 <prgn>dpkg-statoverride</prgn> would be needed in the
7980 maintainer scripts, and that involves packages which use
7981 dynamically allocated user or group ids. In such a
7982 situation, something like the following idiom can be very
7983 helpful in the package's <prgn>postinst</prgn>, where
7984 <tt>sysuser</tt> is a dynamically allocated id:
7986 for i in /usr/bin/foo /usr/sbin/bar
7988 # only do something when no setting exists
7989 if ! dpkg-statoverride --list $i >/dev/null 2>&1
7991 #include: debconf processing, question about foo and bar
7992 if [ "$RET" = "true" ] ; then
7993 dpkg-statoverride --update --add sysuser root 4755 $i
7998 The corresponding code to remove the override when the package
8001 for i in /usr/bin/foo /usr/sbin/bar
8003 if dpkg-statoverride --list $i >/dev/null 2>&1
8005 dpkg-statoverride --remove $i
8015 <chapt id="customized-programs">
8016 <heading>Customized programs</heading>
8018 <sect id="arch-spec">
8019 <heading>Architecture specification strings</heading>
8022 If a program needs to specify an <em>architecture specification
8023 string</em> in some place, it should select one of the strings
8024 provided by <tt>dpkg-architecture -L</tt>. The strings are in
8025 the format <tt><var>os</var>-<var>arch</var></tt>, though the OS
8026 part is sometimes elided, as when the OS is Linux.
8030 Note that we don't want to use
8031 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
8032 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
8033 since this would make our programs incompatible with other
8034 Linux distributions. We also don't use something like
8035 <tt><var>arch</var>-unknown-linux</tt>, since the
8036 <tt>unknown</tt> does not look very good.
8039 <sect1 id="arch-wildcard-spec">
8040 <heading>Architecture wildcards</heading>
8043 A package may specify an architecture wildcard. Architecture
8044 wildcards are in the format <tt>any</tt> (which matches every
8045 architecture), <tt><var>os</var></tt>-any, or
8046 any-<tt><var>cpu</var></tt>. <footnote>
8047 Internally, the package system normalizes the GNU triplets
8048 and the Debian arches into Debian arch triplets (which are
8049 kind of inverted GNU triplets), with the first component of
8050 the triplet representing the libc and ABI in use, and then
8051 does matching against those triplets. However, such
8052 triplets are an internal implementation detail that should
8053 not be used by packages directly. The libc and ABI portion
8054 is handled internally by the package system based on
8055 the <var>os</var> and <var>cpu</var>.
8062 <heading>Daemons</heading>
8065 The configuration files <file>/etc/services</file>,
8066 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
8067 by the <prgn>netbase</prgn> package and must not be modified
8072 If a package requires a new entry in one of these files, the
8073 maintainer should get in contact with the
8074 <prgn>netbase</prgn> maintainer, who will add the entries
8075 and release a new version of the <prgn>netbase</prgn>
8080 The configuration file <file>/etc/inetd.conf</file> must not be
8081 modified by the package's scripts except via the
8082 <prgn>update-inetd</prgn> script or the
8083 <file>DebianNet.pm</file> Perl module. See their documentation
8084 for details on how to add entries.
8088 If a package wants to install an example entry into
8089 <file>/etc/inetd.conf</file>, the entry must be preceded with
8090 exactly one hash character (<tt>#</tt>). Such lines are
8091 treated as "commented out by user" by the
8092 <prgn>update-inetd</prgn> script and are not changed or
8093 activated during package updates.
8098 <heading>Using pseudo-ttys and modifying wtmp, utmp and
8102 Some programs need to create pseudo-ttys. This should be done
8103 using Unix98 ptys if the C library supports it. The resulting
8104 program must not be installed setuid root, unless that
8105 is required for other functionality.
8109 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
8110 <file>/var/log/lastlog</file> must be installed writable by
8111 group <tt>utmp</tt>. Programs which need to modify those
8112 files must be installed setgid <tt>utmp</tt>.
8117 <heading>Editors and pagers</heading>
8120 Some programs have the ability to launch an editor or pager
8121 program to edit or display a text document. Since there are
8122 lots of different editors and pagers available in the Debian
8123 distribution, the system administrator and each user should
8124 have the possibility to choose their preferred editor and
8129 In addition, every program should choose a good default
8130 editor/pager if none is selected by the user or system
8135 Thus, every program that launches an editor or pager must
8136 use the EDITOR or PAGER environment variable to determine
8137 the editor or pager the user wishes to use. If these
8138 variables are not set, the programs <file>/usr/bin/editor</file>
8139 and <file>/usr/bin/pager</file> should be used, respectively.
8143 These two files are managed through the <prgn>dpkg</prgn>
8144 "alternatives" mechanism. Thus every package providing an
8145 editor or pager must call the
8146 <prgn>update-alternatives</prgn> script to register these
8151 If it is very hard to adapt a program to make use of the
8152 EDITOR or PAGER variables, that program may be configured to
8153 use <file>/usr/bin/sensible-editor</file> and
8154 <file>/usr/bin/sensible-pager</file> as the editor or pager
8155 program respectively. These are two scripts provided in the
8156 <package>sensible-utils</package> package that check the EDITOR
8157 and PAGER variables and launch the appropriate program, and fall
8158 back to <file>/usr/bin/editor</file>
8159 and <file>/usr/bin/pager</file> if the variable is not set.
8163 A program may also use the VISUAL environment variable to
8164 determine the user's choice of editor. If it exists, it
8165 should take precedence over EDITOR. This is in fact what
8166 <file>/usr/bin/sensible-editor</file> does.
8170 It is not required for a package to depend on
8171 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
8172 package to provide such virtual packages.<footnote>
8173 The Debian base system already provides an editor and a
8179 <sect id="web-appl">
8180 <heading>Web servers and applications</heading>
8183 This section describes the locations and URLs that should
8184 be used by all web servers and web applications in the
8191 Cgi-bin executable files are installed in the
8193 <example compact="compact">
8194 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
8196 and should be referred to as
8197 <example compact="compact">
8198 http://localhost/cgi-bin/<var>cgi-bin-name</var>
8204 <p>Access to HTML documents</p>
8207 HTML documents for a package are stored in
8208 <file>/usr/share/doc/<var>package</var></file>
8209 and can be referred to as
8210 <example compact="compact">
8211 http://localhost/doc/<var>package</var>/<var>filename</var>
8216 The web server should restrict access to the document
8217 tree so that only clients on the same host can read
8218 the documents. If the web server does not support such
8219 access controls, then it should not provide access at
8220 all, or ask about providing access during installation.
8225 <p>Access to images</p>
8227 It is recommended that images for a package be stored
8228 in <tt>/usr/share/images/<var>package</var></tt> and
8229 may be referred to through an alias <tt>/images/</tt>
8232 http://localhost/images/<package>/<filename>
8239 <p>Web Document Root</p>
8242 Web Applications should try to avoid storing files in
8243 the Web Document Root. Instead they should use the
8244 /usr/share/doc/<var>package</var> directory for
8245 documents and register the Web Application via the
8246 <package>doc-base</package> package. If access to the
8247 web document root is unavoidable then use
8248 <example compact="compact">
8251 as the Document Root. This might be just a symbolic
8252 link to the location where the system administrator
8253 has put the real document root.
8256 <item><p>Providing httpd and/or httpd-cgi</p>
8258 All web servers should provide the virtual package
8259 <tt>httpd</tt>. If a web server has CGI support it should
8260 provide <tt>httpd-cgi</tt> additionally.
8263 All web applications which do not contain CGI scripts should
8264 depend on <tt>httpd</tt>, all those web applications which
8265 <tt>do</tt> contain CGI scripts, should depend on
8273 <sect id="mail-transport-agents">
8274 <heading>Mail transport, delivery and user agents</heading>
8277 Debian packages which process electronic mail, whether mail
8278 user agents (MUAs) or mail transport agents (MTAs), must
8279 ensure that they are compatible with the configuration
8280 decisions below. Failure to do this may result in lost
8281 mail, broken <tt>From:</tt> lines, and other serious brain
8286 The mail spool is <file>/var/mail</file> and the interface to
8287 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8288 the FHS). On older systems, the mail spool may be
8289 physically located in <file>/var/spool/mail</file>, but all
8290 access to the mail spool should be via the
8291 <file>/var/mail</file> symlink. The mail spool is part of the
8292 base system and not part of the MTA package.
8296 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8297 programs (such as IMAP daemons) must lock the mailbox in an
8298 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8299 be combined with dot locking. To avoid deadlocks, a program
8300 should use <tt>fcntl()</tt> first and dot locking after
8301 this, or alternatively implement the two locking methods in
8302 a non blocking way<footnote>
8303 If it is not possible to establish both locks, the
8304 system shouldn't wait for the second lock to be
8305 established, but remove the first lock, wait a (random)
8306 time, and start over locking again.
8307 </footnote>. Using the functions <tt>maillock</tt> and
8308 <tt>mailunlock</tt> provided by the
8309 <tt>liblockfile*</tt><footnote>
8310 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8311 to use these functions.
8312 </footnote> packages is the recommended way to realize this.
8316 Mailboxes are generally either mode 600 and owned by
8317 <var>user</var> or mode 660 and owned by
8318 <tt><var>user</var>:mail</tt><footnote>
8319 There are two traditional permission schemes for mail spools:
8320 mode 600 with all mail delivery done by processes running as
8321 the destination user, or mode 660 and owned by group mail with
8322 mail delivery done by a process running as a system user in
8323 group mail. Historically, Debian required mode 660 mail
8324 spools to enable the latter model, but that model has become
8325 increasingly uncommon and the principle of least privilege
8326 indicates that mail systems that use the first model should
8327 use permissions of 600. If delivery to programs is permitted,
8328 it's easier to keep the mail system secure if the delivery
8329 agent runs as the destination user. Debian Policy therefore
8330 permits either scheme.
8331 </footnote>. The local system administrator may choose a
8332 different permission scheme; packages should not make
8333 assumptions about the permission and ownership of mailboxes
8334 unless required (such as when creating a new mailbox). A MUA
8335 may remove a mailbox (unless it has nonstandard permissions) in
8336 which case the MTA or another MUA must recreate it if needed.
8340 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8341 be setgid mail to do the locking mentioned above (and
8342 must obviously avoid accessing other users' mailboxes
8343 using this privilege).</p>
8346 <file>/etc/aliases</file> is the source file for the system mail
8347 aliases (e.g., postmaster, usenet, etc.), it is the one
8348 which the sysadmin and <prgn>postinst</prgn> scripts may
8349 edit. After <file>/etc/aliases</file> is edited the program or
8350 human editing it must call <prgn>newaliases</prgn>. All MTA
8351 packages must come with a <prgn>newaliases</prgn> program,
8352 even if it does nothing, but older MTA packages did not do
8353 this so programs should not fail if <prgn>newaliases</prgn>
8354 cannot be found. Note that because of this, all MTA
8355 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8356 <tt>Replaces: mail-transport-agent</tt> control file
8361 The convention of writing <tt>forward to
8362 <var>address</var></tt> in the mailbox itself is not
8363 supported. Use a <tt>.forward</tt> file instead.</p>
8366 The <prgn>rmail</prgn> program used by UUCP
8367 for incoming mail should be <file>/usr/sbin/rmail</file>.
8368 Likewise, <prgn>rsmtp</prgn>, for receiving
8369 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8373 If your package needs to know what hostname to use on (for
8374 example) outgoing news and mail messages which are generated
8375 locally, you should use the file <file>/etc/mailname</file>. It
8376 will contain the portion after the username and <tt>@</tt>
8377 (at) sign for email addresses of users on the machine
8378 (followed by a newline).
8382 Such a package should check for the existence of this file
8383 when it is being configured. If it exists, it should be
8384 used without comment, although an MTA's configuration script
8385 may wish to prompt the user even if it finds that this file
8386 exists. If the file does not exist, the package should
8387 prompt the user for the value (preferably using
8388 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8389 as well as using it in the package's configuration. The
8390 prompt should make it clear that the name will not just be
8391 used by that package. For example, in this situation the
8392 <tt>inn</tt> package could say something like:
8393 <example compact="compact">
8394 Please enter the "mail name" of your system. This is the
8395 hostname portion of the address to be shown on outgoing
8396 news and mail messages. The default is
8397 <var>syshostname</var>, your system's host name. Mail
8398 name ["<var>syshostname</var>"]:
8400 where <var>syshostname</var> is the output of <tt>hostname
8406 <heading>News system configuration</heading>
8409 All the configuration files related to the NNTP (news)
8410 servers and clients should be located under
8411 <file>/etc/news</file>.</p>
8414 There are some configuration issues that apply to a number
8415 of news clients and server packages on the machine. These
8419 <tag><file>/etc/news/organization</file></tag>
8421 A string which should appear as the
8422 organization header for all messages posted
8423 by NNTP clients on the machine
8426 <tag><file>/etc/news/server</file></tag>
8428 Contains the FQDN of the upstream NNTP
8429 server, or localhost if the local machine is
8434 Other global files may be added as required for cross-package news
8441 <heading>Programs for the X Window System</heading>
8444 <heading>Providing X support and package priorities</heading>
8447 Programs that can be configured with support for the X
8448 Window System must be configured to do so and must declare
8449 any package dependencies necessary to satisfy their
8450 runtime requirements when using the X Window System. If
8451 such a package is of higher priority than the X packages
8452 on which it depends, it is required that either the
8453 X-specific components be split into a separate package, or
8454 that an alternative version of the package, which includes
8455 X support, be provided, or that the package's priority be
8461 <heading>Packages providing an X server</heading>
8464 Packages that provide an X server that, directly or
8465 indirectly, communicates with real input and display
8466 hardware should declare in their control data that they
8467 provide the virtual package <tt>xserver</tt>.<footnote>
8468 This implements current practice, and provides an
8469 actual policy for usage of the <tt>xserver</tt>
8470 virtual package which appears in the virtual packages
8471 list. In a nutshell, X servers that interface
8472 directly with the display and input hardware or via
8473 another subsystem (e.g., GGI) should provide
8474 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8475 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8481 <heading>Packages providing a terminal emulator</heading>
8484 Packages that provide a terminal emulator for the X Window
8485 System which meet the criteria listed below should declare
8486 in their control data that they provide the virtual
8487 package <tt>x-terminal-emulator</tt>. They should also
8488 register themselves as an alternative for
8489 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8494 To be an <tt>x-terminal-emulator</tt>, a program must:
8495 <list compact="compact">
8497 Be able to emulate a DEC VT100 terminal, or a
8498 compatible terminal.
8502 Support the command-line option <tt>-e
8503 <var>command</var></tt>, which creates a new
8504 terminal window<footnote>
8505 "New terminal window" does not necessarily mean
8506 a new top-level X window directly parented by
8507 the window manager; it could, if the terminal
8508 emulator application were so coded, be a new
8509 "view" in a multiple-document interface (MDI).
8511 and runs the specified <var>command</var>,
8512 interpreting the entirety of the rest of the command
8513 line as a command to pass straight to exec, in the
8514 manner that <tt>xterm</tt> does.
8518 Support the command-line option <tt>-T
8519 <var>title</var></tt>, which creates a new terminal
8520 window with the window title <var>title</var>.
8527 <heading>Packages providing a window manager</heading>
8530 Packages that provide a window manager should declare in
8531 their control data that they provide the virtual package
8532 <tt>x-window-manager</tt>. They should also register
8533 themselves as an alternative for
8534 <file>/usr/bin/x-window-manager</file>, with a priority
8535 calculated as follows:
8536 <list compact="compact">
8538 Start with a priority of 20.
8542 If the window manager supports the Debian menu
8543 system, add 20 points if this support is available
8544 in the package's default configuration (i.e., no
8545 configuration files belonging to the system or user
8546 have to be edited to activate the feature); if
8547 configuration files must be modified, add only 10
8553 If the window manager complies with <url
8554 id="http://www.freedesktop.org/Standards/wm-spec"
8555 name="The Window Manager Specification Project">,
8556 written by the <url id="http://www.freedesktop.org/"
8557 name="Free Desktop Group">, add 40 points.
8561 If the window manager permits the X session to be
8562 restarted using a <em>different</em> window manager
8563 (without killing the X server) in its default
8564 configuration, add 10 points; otherwise add none.
8571 <heading>Packages providing fonts</heading>
8574 Packages that provide fonts for the X Window
8576 For the purposes of Debian Policy, a "font for the X
8577 Window System" is one which is accessed via X protocol
8578 requests. Fonts for the Linux console, for PostScript
8579 renderer, or any other purpose, do not fit this
8580 definition. Any tool which makes such fonts available
8581 to the X Window System, however, must abide by this
8584 must do a number of things to ensure that they are both
8585 available without modification of the X or font server
8586 configuration, and that they do not corrupt files used by
8587 other font packages to register information about
8591 Fonts of any type supported by the X Window System
8592 must be in a separate binary package from any
8593 executables, libraries, or documentation (except
8594 that specific to the fonts shipped, such as their
8595 license information). If one or more of the fonts
8596 so packaged are necessary for proper operation of
8597 the package with which they are associated the font
8598 package may be Recommended; if the fonts merely
8599 provide an enhancement, a Suggests relationship may
8600 be used. Packages must not Depend on font
8602 This is because the X server may retrieve fonts
8603 from the local file system or over the network
8604 from an X font server; the Debian package system
8605 is empowered to deal only with the local
8611 BDF fonts must be converted to PCF fonts with the
8612 <prgn>bdftopcf</prgn> utility (available in the
8613 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8614 placed in a directory that corresponds to their
8616 <list compact="compact">
8618 100 dpi fonts must be placed in
8619 <file>/usr/share/fonts/X11/100dpi/</file>.
8623 75 dpi fonts must be placed in
8624 <file>/usr/share/fonts/X11/75dpi/</file>.
8628 Character-cell fonts, cursor fonts, and other
8629 low-resolution fonts must be placed in
8630 <file>/usr/share/fonts/X11/misc/</file>.
8636 Type 1 fonts must be placed in
8637 <file>/usr/share/fonts/X11/Type1/</file>. If font
8638 metric files are available, they must be placed here
8643 Subdirectories of <file>/usr/share/fonts/X11/</file>
8644 other than those listed above must be neither
8645 created nor used. (The <file>PEX</file>, <file>CID</file>,
8646 <file>Speedo</file>, and <file>cyrillic</file> directories
8647 are excepted for historical reasons, but installation of
8648 files into these directories remains discouraged.)
8652 Font packages may, instead of placing files directly
8653 in the X font directories listed above, provide
8654 symbolic links in that font directory pointing to
8655 the files' actual location in the filesystem. Such
8656 a location must comply with the FHS.
8660 Font packages should not contain both 75dpi and
8661 100dpi versions of a font. If both are available,
8662 they should be provided in separate binary packages
8663 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8664 the names of the packages containing the
8665 corresponding fonts.
8669 Fonts destined for the <file>misc</file> subdirectory
8670 should not be included in the same package as 75dpi
8671 or 100dpi fonts; instead, they should be provided in
8672 a separate package with <tt>-misc</tt> appended to
8677 Font packages must not provide the files
8678 <file>fonts.dir</file>, <file>fonts.alias</file>, or
8679 <file>fonts.scale</file> in a font directory:
8682 <file>fonts.dir</file> files must not be provided at all.
8686 <file>fonts.alias</file> and <file>fonts.scale</file>
8687 files, if needed, should be provided in the
8689 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
8690 where <var>fontdir</var> is the name of the
8692 <file>/usr/share/fonts/X11/</file> where the
8693 package's corresponding fonts are stored
8694 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
8695 <var>package</var> is the name of the package
8696 that provides these fonts, and
8697 <var>extension</var> is either <tt>scale</tt>
8698 or <tt>alias</tt>, whichever corresponds to
8705 Font packages must declare a dependency on
8706 <tt>xfonts-utils</tt> in their control
8711 Font packages that provide one or more
8712 <file>fonts.scale</file> files as described above must
8713 invoke <prgn>update-fonts-scale</prgn> on each
8714 directory into which they installed fonts
8715 <em>before</em> invoking
8716 <prgn>update-fonts-dir</prgn> on that directory.
8717 This invocation must occur in both the
8718 <prgn>postinst</prgn> (for all arguments) and
8719 <prgn>postrm</prgn> (for all arguments except
8720 <tt>upgrade</tt>) scripts.
8724 Font packages that provide one or more
8725 <file>fonts.alias</file> files as described above must
8726 invoke <prgn>update-fonts-alias</prgn> on each
8727 directory into which they installed fonts. This
8728 invocation must occur in both the
8729 <prgn>postinst</prgn> (for all arguments) and
8730 <prgn>postrm</prgn> (for all arguments except
8731 <tt>upgrade</tt>) scripts.
8735 Font packages must invoke
8736 <prgn>update-fonts-dir</prgn> on each directory into
8737 which they installed fonts. This invocation must
8738 occur in both the <prgn>postinst</prgn> (for all
8739 arguments) and <prgn>postrm</prgn> (for all
8740 arguments except <tt>upgrade</tt>) scripts.
8744 Font packages must not provide alias names for the
8745 fonts they include which collide with alias names
8746 already in use by fonts already packaged.
8750 Font packages must not provide fonts with the same
8751 XLFD registry name as another font already packaged.
8757 <sect1 id="appdefaults">
8758 <heading>Application defaults files</heading>
8761 Application defaults files must be installed in the
8762 directory <file>/etc/X11/app-defaults/</file> (use of a
8763 localized subdirectory of <file>/etc/X11/</file> as described
8764 in the <em>X Toolkit Intrinsics - C Language
8765 Interface</em> manual is also permitted). They must be
8766 registered as <tt>conffile</tt>s or handled as
8767 configuration files.
8771 Customization of programs' X resources may also be
8772 supported with the provision of a file with the same name
8773 as that of the package placed in
8774 the <file>/etc/X11/Xresources/</file> directory, which
8775 must be registered as a <tt>conffile</tt> or handled as a
8776 configuration file.<footnote>
8777 Note that this mechanism is not the same as using
8778 app-defaults; app-defaults are tied to the client
8779 binary on the local file system, whereas X resources
8780 are stored in the X server and affect all connecting
8787 <heading>Installation directory issues</heading>
8790 Historically, packages using the X Window System used a
8791 separate set of installation directories from other packages.
8792 This practice has been discontinued and packages using the X
8793 Window System should now generally be installed in the same
8794 directories as any other package. Specifically, packages must
8795 not install files under the <file>/usr/X11R6/</file> directory
8796 and the <file>/usr/X11R6/</file> directory hierarchy should be
8797 regarded as obsolete.
8801 Include files previously installed under
8802 <file>/usr/X11R6/include/X11/</file> should be installed into
8803 <file>/usr/include/X11/</file>. For files previously
8804 installed into subdirectories of
8805 <file>/usr/X11R6/lib/X11/</file>, package maintainers should
8806 determine if subdirectories of <file>/usr/lib/</file> and
8807 <file>/usr/share/</file> can be used. If not, a subdirectory
8808 of <file>/usr/lib/X11/</file> should be used.
8812 Configuration files for window, display, or session managers
8813 or other applications that are tightly integrated with the X
8814 Window System may be placed in a subdirectory
8815 of <file>/etc/X11/</file> corresponding to the package name.
8816 Other X Window System applications should use
8817 the <file>/etc/</file> directory unless otherwise mandated by
8818 policy (such as for <ref id="appdefaults">).
8823 <heading>The OSF/Motif and OpenMotif libraries</heading>
8826 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8827 OpenMotif libraries</em><footnote>
8828 OSF/Motif and OpenMotif are collectively referred to as
8829 "Motif" in this policy document.
8831 should be compiled against and tested with LessTif (a free
8832 re-implementation of Motif) instead. If the maintainer
8833 judges that the program or programs do not work
8834 sufficiently well with LessTif to be distributed and
8835 supported, but do so when compiled against Motif, then two
8836 versions of the package should be created; one linked
8837 statically against Motif and with <tt>-smotif</tt>
8838 appended to the package name, and one linked dynamically
8839 against Motif and with <tt>-dmotif</tt> appended to the
8844 Both Motif-linked versions are dependent
8845 upon non-DFSG-compliant software and thus cannot be
8846 uploaded to the <em>main</em> distribution; if the
8847 software is itself DFSG-compliant it may be uploaded to
8848 the <em>contrib</em> distribution. While known existing
8849 versions of Motif permit unlimited redistribution of
8850 binaries linked against the library (whether statically or
8851 dynamically), it is the package maintainer's
8852 responsibility to determine whether this is permitted by
8853 the license of the copy of Motif in their possession.
8859 <heading>Perl programs and modules</heading>
8862 Perl programs and modules should follow the current Perl policy.
8866 The Perl policy can be found in the <tt>perl-policy</tt>
8867 files in the <tt>debian-policy</tt> package.
8868 It is also available from the Debian web mirrors at
8869 <tt><url name="/doc/packaging-manuals/perl-policy/"
8870 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8875 <heading>Emacs lisp programs</heading>
8878 Please refer to the "Debian Emacs Policy" for details of how to
8879 package emacs lisp programs.
8883 The Emacs policy is available in
8884 <file>debian-emacs-policy.gz</file> of the
8885 <package>emacsen-common</package> package.
8886 It is also available from the Debian web mirrors at
8887 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8888 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8893 <heading>Games</heading>
8896 The permissions on <file>/var/games</file> are mode 755, owner
8897 <tt>root</tt> and group <tt>root</tt>.
8901 Each game decides on its own security policy.</p>
8904 Games which require protected, privileged access to
8905 high-score files, saved games, etc., may be made
8906 set-<em>group</em>-id (mode 2755) and owned by
8907 <tt>root:games</tt>, and use files and directories with
8908 appropriate permissions (770 <tt>root:games</tt>, for
8909 example). They must not be made
8910 set-<em>user</em>-id, as this causes security problems. (If
8911 an attacker can subvert any set-user-id game they can
8912 overwrite the executable of any other, causing other players
8913 of these games to run a Trojan horse program. With a
8914 set-group-id game the attacker only gets access to less
8915 important game data, and if they can get at the other
8916 players' accounts at all it will take considerably more
8920 Some packages, for example some fortune cookie programs, are
8921 configured by the upstream authors to install with their
8922 data files or other static information made unreadable so
8923 that they can only be accessed through set-id programs
8924 provided. You should not do this in a Debian package: anyone can
8925 download the <file>.deb</file> file and read the data from it,
8926 so there is no point making the files unreadable. Not
8927 making the files unreadable also means that you don't have
8928 to make so many programs set-id, which reduces the risk of a
8932 As described in the FHS, binaries of games should be
8933 installed in the directory <file>/usr/games</file>. This also
8934 applies to games that use the X Window System. Manual pages
8935 for games (X and non-X games) should be installed in
8936 <file>/usr/share/man/man6</file>.</p>
8942 <heading>Documentation</heading>
8945 <heading>Manual pages</heading>
8948 You should install manual pages in <prgn>nroff</prgn> source
8949 form, in appropriate places under <file>/usr/share/man</file>.
8950 You should only use sections 1 to 9 (see the FHS for more
8951 details). You must not install a pre-formatted "cat page".
8955 Each program, utility, and function should have an
8956 associated manual page included in the same package. It is
8957 suggested that all configuration files also have a manual
8958 page included as well. Manual pages for protocols and other
8959 auxiliary things are optional.
8963 If no manual page is available, this is considered as a bug
8964 and should be reported to the Debian Bug Tracking System (the
8965 maintainer of the package is allowed to write this bug report
8966 themselves, if they so desire). Do not close the bug report
8967 until a proper man page is available.<footnote>
8968 It is not very hard to write a man page. See the
8969 <url id="http://www.schweikhardt.net/man_page_howto.html"
8970 name="Man-Page-HOWTO">,
8971 <manref name="man" section="7">, the examples
8972 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8973 the helper program <prgn>help2man</prgn>, or the
8974 directory <file>/usr/share/doc/man-db/examples</file>.
8979 You may forward a complaint about a missing man page to the
8980 upstream authors, and mark the bug as forwarded in the
8981 Debian bug tracking system. Even though the GNU Project do
8982 not in general consider the lack of a man page to be a bug,
8983 we do; if they tell you that they don't consider it a bug
8984 you should leave the bug in our bug tracking system open
8989 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8993 If one man page needs to be accessible via several names it
8994 is better to use a symbolic link than the <file>.so</file>
8995 feature, but there is no need to fiddle with the relevant
8996 parts of the upstream source to change from <file>.so</file> to
8997 symlinks: don't do it unless it's easy. You should not
8998 create hard links in the manual page directories, nor put
8999 absolute filenames in <file>.so</file> directives. The filename
9000 in a <file>.so</file> in a man page should be relative to the
9001 base of the man page tree (usually
9002 <file>/usr/share/man</file>). If you do not create any links
9003 (whether symlinks, hard links, or <tt>.so</tt> directives)
9004 in the file system to the alternate names of the man page,
9005 then you should not rely on <prgn>man</prgn> finding your
9006 man page under those names based solely on the information in
9007 the man page's header.<footnote>
9008 Supporting this in <prgn>man</prgn> often requires
9009 unreasonable processing time to find a manual page or to
9010 report that none exists, and moves knowledge into man's
9011 database that would be better left in the file system.
9012 This support is therefore deprecated and will cease to
9013 be present in the future.
9018 Manual pages in locale-specific subdirectories of
9019 <file>/usr/share/man</file> should use either UTF-8 or the usual
9020 legacy encoding for that language (normally the one corresponding
9021 to the shortest relevant locale name in
9022 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
9023 <file>/usr/share/man/fr</file> should use either UTF-8 or
9024 ISO-8859-1.<footnote>
9025 <prgn>man</prgn> will automatically detect whether UTF-8 is in
9026 use. In future, all manual pages will be required to use
9032 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
9033 included in the subdirectory name unless it indicates a
9034 significant difference in the language, as this excludes
9035 speakers of the language in other countries.<footnote>
9036 At the time of writing, Chinese and Portuguese are the main
9037 languages with such differences, so <file>pt_BR</file>,
9038 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
9043 If a localized version of a manual page is provided, it should
9044 either be up-to-date or it should be obvious to the reader that
9045 it is outdated and the original manual page should be used
9046 instead. This can be done either by a note at the beginning of
9047 the manual page or by showing the missing or changed portions in
9048 the original language instead of the target language.
9053 <heading>Info documents</heading>
9056 Info documents should be installed in <file>/usr/share/info</file>.
9057 They should be compressed with <tt>gzip -9</tt>.
9061 The <prgn>install-info</prgn> program maintains a directory of
9062 installed info documents in <file>/usr/share/info/dir</file> for
9063 the use of info readers.<footnote>
9064 It was previously necessary for packages installing info
9065 documents to run <prgn>install-info</prgn> from maintainer
9066 scripts. This is no longer necessary. The installation
9067 system now uses dpkg triggers.
9069 This file must not be included in packages. Packages containing
9070 info documents should depend on <tt>dpkg (>= 1.15.4) |
9071 install-info</tt> to ensure that the directory file is properly
9072 rebuilt during partial upgrades from Debian 5.0 (lenny) and
9077 Info documents should contain section and directory entry
9078 information in the document for the use
9079 of <prgn>install-info</prgn>. The section should be specified
9080 via a line starting with <tt>INFO-DIR-SECTION</tt> followed by a
9081 space and the section of this info page. The directory entry or
9082 entries should be included between
9083 a <tt>START-INFO-DIR-ENTRY</tt> line and
9084 an <tt>END-INFO-DIR-ENTRY</tt> line. For example:
9086 INFO-DIR-SECTION Individual utilities
9087 START-INFO-DIR-ENTRY
9088 * example: (example). An example info directory entry.
9091 To determine which section to use, you should look
9092 at <file>/usr/share/info/dir</file> on your system and choose
9093 the most relevant (or create a new section if none of the
9094 current sections are relevant).<footnote>
9095 Normally, info documents are generated from Texinfo source.
9096 To include this information in the generated info document, if
9097 it is absent, add commands like:
9099 @dircategory Individual utilities
9101 * example: (example). An example info directory entry.
9104 to the Texinfo source of the document and ensure that the info
9105 documents are rebuilt from source during the package build.
9111 <heading>Additional documentation</heading>
9114 Any additional documentation that comes with the package may
9115 be installed at the discretion of the package maintainer.
9116 Plain text documentation should be installed in the directory
9117 <file>/usr/share/doc/<var>package</var></file>, where
9118 <var>package</var> is the name of the package, and
9119 compressed with <tt>gzip -9</tt> unless it is small.
9123 If a package comes with large amounts of documentation which
9124 many users of the package will not require you should create
9125 a separate binary package to contain it, so that it does not
9126 take up disk space on the machines of users who do not need
9127 or want it installed.</p>
9130 It is often a good idea to put text information files
9131 (<file>README</file>s, changelogs, and so forth) that come with
9132 the source package in <file>/usr/share/doc/<var>package</var></file>
9133 in the binary package. However, you don't need to install
9134 the instructions for building and installing the package, of
9138 Packages must not require the existence of any files in
9139 <file>/usr/share/doc/</file> in order to function
9141 The system administrator should be able to
9142 delete files in <file>/usr/share/doc/</file> without causing
9143 any programs to break.
9145 Any files that are referenced by programs but are also
9146 useful as stand alone documentation should be installed under
9147 <file>/usr/share/<var>package</var>/</file> with symbolic links from
9148 <file>/usr/share/doc/<var>package</var></file>.
9152 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9153 link to another directory in <file>/usr/share/doc</file> only if
9154 the two packages both come from the same source and the
9155 first package Depends on the second.<footnote>
9157 Please note that this does not override the section on
9158 changelog files below, so the file
9159 <file>/usr/share/doc/<var>package</var>/changelog.Debian.gz</file>
9160 must refer to the changelog for the current version of
9161 <var>package</var> in question. In practice, this means
9162 that the sources of the target and the destination of the
9163 symlink must be the same (same source package and
9170 Former Debian releases placed all additional documentation
9171 in <file>/usr/doc/<var>package</var></file>. This has been
9172 changed to <file>/usr/share/doc/<var>package</var></file>,
9173 and packages must not put documentation in the directory
9174 <file>/usr/doc/<var>package</var></file>. <footnote>
9175 At this phase of the transition, we no longer require a
9176 symbolic link in <file>/usr/doc/</file>. At a later point,
9177 policy shall change to make the symbolic links a bug.
9183 <heading>Preferred documentation formats</heading>
9186 The unification of Debian documentation is being carried out
9190 If your package comes with extensive documentation in a
9191 markup format that can be converted to various other formats
9192 you should if possible ship HTML versions in a binary
9193 package, in the directory
9194 <file>/usr/share/doc/<var>appropriate-package</var></file> or
9195 its subdirectories.<footnote>
9196 The rationale: The important thing here is that HTML
9197 docs should be available in <em>some</em> package, not
9198 necessarily in the main binary package.
9203 Other formats such as PostScript may be provided at the
9204 package maintainer's discretion.
9208 <sect id="copyrightfile">
9209 <heading>Copyright information</heading>
9212 Every package must be accompanied by a verbatim copy of its
9213 copyright information and distribution license in the file
9214 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
9215 file must neither be compressed nor be a symbolic link.
9219 In addition, the copyright file must say where the upstream
9220 sources (if any) were obtained. It should name the original
9221 authors of the package and the Debian maintainer(s) who were
9222 involved with its creation.
9226 Packages in the <em>contrib</em> or <em>non-free</em> archive
9227 areas should state in the copyright file that the package is not
9228 part of the Debian GNU/Linux distribution and briefly explain
9233 A copy of the file which will be installed in
9234 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9235 be in <file>debian/copyright</file> in the source package.
9239 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9240 link to another directory in <file>/usr/share/doc</file> only if
9241 the two packages both come from the same source and the
9242 first package Depends on the second. These rules are
9243 important because copyrights must be extractable by
9248 Packages distributed under the Apache license (version 2.0), the
9249 Artistic license, the GNU GPL (version 2 or 3), the GNU LGPL
9250 (versions 2, 2.1, or 3), and the GNU FDL (versions 1.2 or 1.3)
9251 should refer to the corresponding files
9252 under <file>/usr/share/common-licenses</file>,<footnote>
9255 <file>/usr/share/common-licenses/Apache-2.0</file>,
9256 <file>/usr/share/common-licenses/Artistic</file>,
9257 <file>/usr/share/common-licenses/GPL-2</file>,
9258 <file>/usr/share/common-licenses/GPL-3</file>,
9259 <file>/usr/share/common-licenses/LGPL-2</file>,
9260 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9261 <file>/usr/share/common-licenses/LGPL-3</file>,
9262 <file>/usr/share/common-licenses/GFDL-1.2</file>, and
9263 <file>/usr/share/common-licenses/GFDL-1.3</file>
9264 respectively. The University of California BSD license is
9265 also included in <package>base-files</package> as
9266 <file>/usr/share/common-licenses/BSD</file>, but given the
9267 brevity of this license, its specificity to code whose
9268 copyright is held by the Regents of the Univesrity of
9269 California, and the frequency of minor wording changes, its
9270 text should be included in the copyright file rather than
9271 referencing this file.
9273 </footnote> rather than quoting them in the copyright
9278 You should not use the copyright file as a general <file>README</file>
9279 file. If your package has such a file it should be
9280 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9281 <file>README.Debian</file> or some other appropriate place.</p>
9285 <heading>Examples</heading>
9288 Any examples (configurations, source files, whatever),
9289 should be installed in a directory
9290 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9291 files should not be referenced by any program: they're there
9292 for the benefit of the system administrator and users as
9293 documentation only. Architecture-specific example files
9294 should be installed in a directory
9295 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9297 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9298 latter directory itself may be a symbolic link to the
9303 If the purpose of a package is to provide examples, then the
9304 example files may be installed into
9305 <file>/usr/share/doc/<var>package</var></file>.
9309 <sect id="changelogs">
9310 <heading>Changelog files</heading>
9313 Packages that are not Debian-native must contain a
9314 compressed copy of the <file>debian/changelog</file> file from
9315 the Debian source tree in
9316 <file>/usr/share/doc/<var>package</var></file> with the name
9317 <file>changelog.Debian.gz</file>.
9321 If an upstream changelog is available, it should be accessible as
9322 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9323 plain text. If the upstream changelog is distributed in
9324 HTML, it should be made available in that form as
9325 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9326 and a plain text <file>changelog.gz</file> should be generated
9327 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9328 the upstream changelog files do not already conform to this
9329 naming convention, then this may be achieved either by
9330 renaming the files, or by adding a symbolic link, at the
9331 maintainer's discretion.<footnote>
9332 Rationale: People should not have to look in places for
9333 upstream changelogs merely because they are given
9334 different names or are distributed in HTML format.
9339 All of these files should be installed compressed using
9340 <tt>gzip -9</tt>, as they will become large with time even
9341 if they start out small.
9345 If the package has only one changelog which is used both as
9346 the Debian changelog and the upstream one because there is
9347 no separate upstream maintainer then that changelog should
9348 usually be installed as
9349 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9350 there is a separate upstream maintainer, but no upstream
9351 changelog, then the Debian changelog should still be called
9352 <file>changelog.Debian.gz</file>.
9356 For details about the format and contents of the Debian
9357 changelog file, please see <ref id="dpkgchangelog">.
9362 <appendix id="pkg-scope">
9363 <heading>Introduction and scope of these appendices</heading>
9366 These appendices are taken essentially verbatim from the
9367 now-deprecated Packaging Manual, version 3.2.1.0. They are
9368 the chapters which are likely to be of use to package
9369 maintainers and which have not already been included in the
9370 policy document itself. Most of these sections are very likely
9371 not relevant to policy; they should be treated as
9372 documentation for the packaging system. Please note that these
9373 appendices are included for convenience, and for historical
9374 reasons: they used to be part of policy package, and they have
9375 not yet been incorporated into dpkg documentation. However,
9376 they still have value, and hence they are presented here.
9380 They have not yet been checked to ensure that they are
9381 compatible with the contents of policy, and if there are any
9382 contradictions, the version in the main policy document takes
9383 precedence. The remaining chapters of the old Packaging
9384 Manual have also not been read in detail to ensure that there
9385 are not parts which have been left out. Both of these will be
9390 Certain parts of the Packaging manual were integrated into the
9391 Policy Manual proper, and removed from the appendices. Links
9392 have been placed from the old locations to the new ones.
9396 <prgn>dpkg</prgn> is a suite of programs for creating binary
9397 package files and installing and removing them on Unix
9399 <prgn>dpkg</prgn> is targeted primarily at Debian
9400 GNU/Linux, but may work on or be ported to other
9406 The binary packages are designed for the management of
9407 installed executable programs (usually compiled binaries) and
9408 their associated data, though source code examples and
9409 documentation are provided as part of some packages.</p>
9412 This manual describes the technical aspects of creating Debian
9413 binary packages (<file>.deb</file> files). It documents the
9414 behavior of the package management programs
9415 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9416 they interact with packages.</p>
9419 It also documents the interaction between
9420 <prgn>dselect</prgn>'s core and the access method scripts it
9421 uses to actually install the selected packages, and describes
9422 how to create a new access method.</p>
9425 This manual does not go into detail about the options and
9426 usage of the package building and installation tools. It
9427 should therefore be read in conjunction with those programs'
9432 The utility programs which are provided with <prgn>dpkg</prgn>
9433 for managing various system configuration and similar issues,
9434 such as <prgn>update-rc.d</prgn> and
9435 <prgn>install-info</prgn>, are not described in detail here -
9436 please see their man pages.
9440 It is assumed that the reader is reasonably familiar with the
9441 <prgn>dpkg</prgn> System Administrators' manual.
9442 Unfortunately this manual does not yet exist.
9446 The Debian version of the FSF's GNU hello program is provided
9447 as an example for people wishing to create Debian
9448 packages. The Debian <prgn>debmake</prgn> package is
9449 recommended as a very helpful tool in creating and maintaining
9450 Debian packages. However, while the tools and examples are
9451 helpful, they do not replace the need to read and follow the
9452 Policy and Programmer's Manual.</p>
9455 <appendix id="pkg-binarypkg">
9456 <heading>Binary packages (from old Packaging Manual)</heading>
9459 The binary package has two main sections. The first part
9460 consists of various control information files and scripts used
9461 by <prgn>dpkg</prgn> when installing and removing. See <ref
9462 id="pkg-controlarea">.
9466 The second part is an archive containing the files and
9467 directories to be installed.
9471 In the future binary packages may also contain other
9472 components, such as checksums and digital signatures. The
9473 format for the archive is described in full in the
9474 <file>deb(5)</file> man page.
9478 <sect id="pkg-bincreating"><heading>Creating package files -
9479 <prgn>dpkg-deb</prgn>
9483 All manipulation of binary package files is done by
9484 <prgn>dpkg-deb</prgn>; it's the only program that has
9485 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9486 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9487 will spot that the options requested are appropriate to
9488 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9493 In order to create a binary package you must make a
9494 directory tree which contains all the files and directories
9495 you want to have in the file system data part of the package.
9496 In Debian-format source packages this directory is usually
9497 <file>debian/tmp</file>, relative to the top of the package's
9502 They should have the locations (relative to the root of the
9503 directory tree you're constructing) ownerships and
9504 permissions which you want them to have on the system when
9509 With current versions of <prgn>dpkg</prgn> the uid/username
9510 and gid/groupname mappings for the users and groups being
9511 used should be the same on the system where the package is
9512 built and the one where it is installed.
9516 You need to add one special directory to the root of the
9517 miniature file system tree you're creating:
9518 <prgn>DEBIAN</prgn>. It should contain the control
9519 information files, notably the binary package control file
9520 (see <ref id="pkg-controlfile">).
9524 The <prgn>DEBIAN</prgn> directory will not appear in the
9525 file system archive of the package, and so won't be installed
9526 by <prgn>dpkg</prgn> when the package is installed.
9530 When you've prepared the package, you should invoke:
9532 dpkg --build <var>directory</var>
9537 This will build the package in
9538 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9539 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9540 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9545 See the man page <manref name="dpkg-deb" section="8"> for details of how
9546 to examine the contents of this newly-created file. You may find the
9547 output of following commands enlightening:
9549 dpkg-deb --info <var>filename</var>.deb
9550 dpkg-deb --contents <var>filename</var>.deb
9551 dpkg --contents <var>filename</var>.deb
9553 To view the copyright file for a package you could use this command:
9555 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
9560 <sect id="pkg-controlarea">
9561 <heading>Package control information files</heading>
9564 The control information portion of a binary package is a
9565 collection of files with names known to <prgn>dpkg</prgn>.
9566 It will treat the contents of these files specially - some
9567 of them contain information used by <prgn>dpkg</prgn> when
9568 installing or removing the package; others are scripts which
9569 the package maintainer wants <prgn>dpkg</prgn> to run.
9573 It is possible to put other files in the package control
9574 area, but this is not generally a good idea (though they
9575 will largely be ignored).
9579 Here is a brief list of the control info files supported by
9580 <prgn>dpkg</prgn> and a summary of what they're used for.
9585 <tag><tt>control</tt>
9588 This is the key description file used by
9589 <prgn>dpkg</prgn>. It specifies the package's name
9590 and version, gives its description for the user,
9591 states its relationships with other packages, and so
9592 forth. See <ref id="sourcecontrolfiles"> and
9593 <ref id="binarycontrolfiles">.
9597 It is usually generated automatically from information
9598 in the source package by the
9599 <prgn>dpkg-gencontrol</prgn> program, and with
9600 assistance from <prgn>dpkg-shlibdeps</prgn>.
9601 See <ref id="pkg-sourcetools">.
9605 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9610 These are executable files (usually scripts) which
9611 <prgn>dpkg</prgn> runs during installation, upgrade
9612 and removal of packages. They allow the package to
9613 deal with matters which are particular to that package
9614 or require more complicated processing than that
9615 provided by <prgn>dpkg</prgn>. Details of when and
9616 how they are called are in <ref id="maintainerscripts">.
9620 It is very important to make these scripts idempotent.
9621 See <ref id="idempotency">.
9625 The maintainer scripts are not guaranteed to run with a
9626 controlling terminal and may not be able to interact with
9627 the user. See <ref id="controllingterminal">.
9631 <tag><tt>conffiles</tt>
9634 This file contains a list of configuration files which
9635 are to be handled automatically by <prgn>dpkg</prgn>
9636 (see <ref id="pkg-conffiles">). Note that not necessarily
9637 every configuration file should be listed here.
9640 <tag><tt>shlibs</tt>
9643 This file contains a list of the shared libraries
9644 supplied by the package, with dependency details for
9645 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9646 when it determines what dependencies are required in a
9647 package control file. The <tt>shlibs</tt> file format
9648 is described on <ref id="shlibs">.
9653 <sect id="pkg-controlfile">
9654 <heading>The main control information file: <tt>control</tt></heading>
9657 The most important control information file used by
9658 <prgn>dpkg</prgn> when it installs a package is
9659 <tt>control</tt>. It contains all the package's "vital
9664 The binary package control files of packages built from
9665 Debian sources are made by a special tool,
9666 <prgn>dpkg-gencontrol</prgn>, which reads
9667 <file>debian/control</file> and <file>debian/changelog</file> to
9668 find the information it needs. See <ref id="pkg-sourcepkg"> for
9673 The fields in binary package control files are listed in
9674 <ref id="binarycontrolfiles">.
9678 A description of the syntax of control files and the purpose
9679 of the fields is available in <ref id="controlfields">.
9684 <heading>Time Stamps</heading>
9687 See <ref id="timestamps">.
9692 <appendix id="pkg-sourcepkg">
9693 <heading>Source packages (from old Packaging Manual) </heading>
9696 The Debian binary packages in the distribution are generated
9697 from Debian sources, which are in a special format to assist
9698 the easy and automatic building of binaries.
9701 <sect id="pkg-sourcetools">
9702 <heading>Tools for processing source packages</heading>
9705 Various tools are provided for manipulating source packages;
9706 they pack and unpack sources and help build of binary
9707 packages and help manage the distribution of new versions.
9711 They are introduced and typical uses described here; see
9712 <manref name="dpkg-source" section="1"> for full
9713 documentation about their arguments and operation.
9717 For examples of how to construct a Debian source package,
9718 and how to use those utilities that are used by Debian
9719 source packages, please see the <prgn>hello</prgn> example
9723 <sect1 id="pkg-dpkg-source">
9725 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
9730 This program is frequently used by hand, and is also
9731 called from package-independent automated building scripts
9732 such as <prgn>dpkg-buildpackage</prgn>.
9736 To unpack a package it is typically invoked with
9738 dpkg-source -x <var>.../path/to/filename</var>.dsc
9743 with the <file><var>filename</var>.tar.gz</file> and
9744 <file><var>filename</var>.diff.gz</file> (if applicable) in
9745 the same directory. It unpacks into
9746 <file><var>package</var>-<var>version</var></file>, and if
9748 <file><var>package</var>-<var>version</var>.orig</file>, in
9749 the current directory.
9753 To create a packed source archive it is typically invoked:
9755 dpkg-source -b <var>package</var>-<var>version</var>
9760 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
9761 <file>.diff.gz</file> (if appropriate) in the current
9762 directory. <prgn>dpkg-source</prgn> does not clean the
9763 source tree first - this must be done separately if it is
9768 See also <ref id="pkg-sourcearchives">.</p>
9772 <sect1 id="pkg-dpkg-buildpackage">
9774 <prgn>dpkg-buildpackage</prgn> - overall package-building
9779 <prgn>dpkg-buildpackage</prgn> is a script which invokes
9780 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
9781 targets <tt>clean</tt>, <tt>build</tt> and
9782 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
9783 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
9784 source and binary package upload.
9788 It is usually invoked by hand from the top level of the
9789 built or unbuilt source directory. It may be invoked with
9790 no arguments; useful arguments include:
9791 <taglist compact="compact">
9792 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
9795 Do not sign the <tt>.changes</tt> file or the
9796 source package <tt>.dsc</tt> file, respectively.</p>
9798 <tag><tt>-p<var>sign-command</var></tt></tag>
9801 Invoke <var>sign-command</var> instead of finding
9802 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
9803 <var>sign-command</var> must behave just like
9804 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9806 <tag><tt>-r<var>root-command</var></tt></tag>
9809 When root privilege is required, invoke the command
9810 <var>root-command</var>. <var>root-command</var>
9811 should invoke its first argument as a command, from
9812 the <prgn>PATH</prgn> if necessary, and pass its
9813 second and subsequent arguments to the command it
9814 calls. If no <var>root-command</var> is supplied
9815 then <var>dpkg-buildpackage</var> will take no
9816 special action to gain root privilege, so that for
9817 most packages it will have to be invoked as root to
9820 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9823 Two types of binary-only build and upload - see
9824 <manref name="dpkg-source" section="1">.
9831 <sect1 id="pkg-dpkg-gencontrol">
9833 <prgn>dpkg-gencontrol</prgn> - generates binary package
9838 This program is usually called from <file>debian/rules</file>
9839 (see <ref id="pkg-sourcetree">) in the top level of the source
9844 This is usually done just before the files and directories in the
9845 temporary directory tree where the package is being built have their
9846 permissions and ownerships set and the package is constructed using
9847 <prgn>dpkg-deb/</prgn>
9849 This is so that the control file which is produced has
9850 the right permissions
9855 <prgn>dpkg-gencontrol</prgn> must be called after all the
9856 files which are to go into the package have been placed in
9857 the temporary build directory, so that its calculation of
9858 the installed size of a package is correct.
9862 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9863 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9864 variable substitutions created by
9865 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9870 For a package which generates only one binary package, and
9871 which builds it in <file>debian/tmp</file> relative to the top
9872 of the source package, it is usually sufficient to call
9873 <prgn>dpkg-gencontrol</prgn>.
9877 Sources which build several binaries will typically need
9880 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9881 </example> The <tt>-P</tt> tells
9882 <prgn>dpkg-gencontrol</prgn> that the package is being
9883 built in a non-default directory, and the <tt>-p</tt>
9884 tells it which package's control file should be generated.
9888 <prgn>dpkg-gencontrol</prgn> also adds information to the
9889 list of files in <file>debian/files</file>, for the benefit of
9890 (for example) a future invocation of
9891 <prgn>dpkg-genchanges</prgn>.</p>
9894 <sect1 id="pkg-dpkg-shlibdeps">
9896 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9901 This program is usually called from <file>debian/rules</file>
9902 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9903 id="pkg-sourcetree">), in the top level of the source tree.
9907 Its arguments are executables and shared libraries
9910 They may be specified either in the locations in the
9911 source tree where they are created or in the locations
9912 in the temporary build tree where they are installed
9913 prior to binary package creation.
9915 </footnote> for which shared library dependencies should
9916 be included in the binary package's control file.
9920 If some of the found shared libraries should only
9921 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9922 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9923 by using the <tt>-d<var>dependency-field</var></tt> option
9924 before those executable(s). (Each <tt>-d</tt> option
9925 takes effect until the next <tt>-d</tt>.)
9929 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9930 output control file to be modified. Instead by default it
9931 adds to the <file>debian/substvars</file> file variable
9932 settings like <tt>shlibs:Depends</tt>. These variable
9933 settings must be referenced in dependency fields in the
9934 appropriate per-binary-package sections of the source
9939 For example, a package that generates an essential part
9940 which requires dependencies, and optional parts that
9941 which only require a recommendation, would separate those
9942 two sets of dependencies into two different fields.<footnote>
9943 At the time of writing, an example for this was the
9944 <package/xmms/ package, with Depends used for the xmms
9945 executable, Recommends for the plug-ins and Suggests for
9946 even more optional features provided by unzip.
9948 It can say in its <file>debian/rules</file>:
9950 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9951 -dRecommends <var>optionalpart anotheroptionalpart</var>
9953 and then in its main control file <file>debian/control</file>:
9956 Depends: ${shlibs:Depends}
9957 Recommends: ${shlibs:Recommends}
9963 Sources which produce several binary packages with
9964 different shared library dependency requirements can use
9965 the <tt>-p<var>varnameprefix</var></tt> option to override
9966 the default <tt>shlibs:</tt> prefix (one invocation of
9967 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9968 They can thus produce several sets of dependency
9969 variables, each of the form
9970 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9971 which can be referred to in the appropriate parts of the
9972 binary package control files.
9977 <sect1 id="pkg-dpkg-distaddfile">
9979 <prgn>dpkg-distaddfile</prgn> - adds a file to
9980 <file>debian/files</file>
9984 Some packages' uploads need to include files other than
9985 the source and binary package files.
9989 <prgn>dpkg-distaddfile</prgn> adds a file to the
9990 <file>debian/files</file> file so that it will be included in
9991 the <file>.changes</file> file when
9992 <prgn>dpkg-genchanges</prgn> is run.
9996 It is usually invoked from the <tt>binary</tt> target of
9997 <file>debian/rules</file>:
9999 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
10001 The <var>filename</var> is relative to the directory where
10002 <prgn>dpkg-genchanges</prgn> will expect to find it - this
10003 is usually the directory above the top level of the source
10004 tree. The <file>debian/rules</file> target should put the
10005 file there just before or just after calling
10006 <prgn>dpkg-distaddfile</prgn>.
10010 The <var>section</var> and <var>priority</var> are passed
10011 unchanged into the resulting <file>.changes</file> file.
10016 <sect1 id="pkg-dpkg-genchanges">
10018 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
10019 upload control file
10023 This program is usually called by package-independent
10024 automatic building scripts such as
10025 <prgn>dpkg-buildpackage</prgn>, but it may also be called
10030 It is usually called in the top level of a built source
10031 tree, and when invoked with no arguments will print out a
10032 straightforward <file>.changes</file> file based on the
10033 information in the source package's changelog and control
10034 file and the binary and source packages which should have
10040 <sect1 id="pkg-dpkg-parsechangelog">
10042 <prgn>dpkg-parsechangelog</prgn> - produces parsed
10043 representation of a changelog
10047 This program is used internally by
10048 <prgn>dpkg-source</prgn> et al. It may also occasionally
10049 be useful in <file>debian/rules</file> and elsewhere. It
10050 parses a changelog, <file>debian/changelog</file> by default,
10051 and prints a control-file format representation of the
10052 information in it to standard output.
10056 <sect1 id="pkg-dpkg-architecture">
10058 <prgn>dpkg-architecture</prgn> - information about the build and
10063 This program can be used manually, but is also invoked by
10064 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
10065 environment or make variables which specify the build and host
10066 architecture for the package building process.
10071 <sect id="pkg-sourcetree">
10072 <heading>The Debianised source tree</heading>
10075 The source archive scheme described later is intended to
10076 allow a Debianised source tree with some associated control
10077 information to be reproduced and transported easily. The
10078 Debianised source tree is a version of the original program
10079 with certain files added for the benefit of the
10080 Debianisation process, and with any other changes required
10081 made to the rest of the source code and installation
10086 The extra files created for Debian are in the subdirectory
10087 <file>debian</file> of the top level of the Debianised source
10088 tree. They are described below.
10091 <sect1 id="pkg-debianrules">
10092 <heading><file>debian/rules</file> - the main building script</heading>
10095 See <ref id="debianrules">.
10099 <sect1 id="pkg-srcsubstvars">
10100 <heading><file>debian/substvars</file> and variable substitutions</heading>
10103 See <ref id="substvars">.
10109 <heading><file>debian/files</file></heading>
10112 See <ref id="debianfiles">.
10116 <sect1><heading><file>debian/tmp</file>
10120 This is the canonical temporary location for the
10121 construction of binary packages by the <tt>binary</tt>
10122 target. The directory <file>tmp</file> serves as the root of
10123 the file system tree as it is being constructed (for
10124 example, by using the package's upstream makefiles install
10125 targets and redirecting the output there), and it also
10126 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10127 id="pkg-bincreating">.
10131 If several binary packages are generated from the same
10132 source tree it is usual to use several
10133 <file>debian/tmp<var>something</var></file> directories, for
10134 example <file>tmp-a</file> or <file>tmp-doc</file>.
10138 Whatever <file>tmp</file> directories are created and used by
10139 <tt>binary</tt> must of course be removed by the
10140 <tt>clean</tt> target.</p></sect1>
10144 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10148 As it exists on the FTP site, a Debian source package
10149 consists of three related files. You must have the right
10150 versions of all three to be able to use them.
10155 <tag>Debian source control file - <tt>.dsc</tt></tag>
10157 This file is a control file used by <prgn>dpkg-source</prgn>
10158 to extract a source package.
10159 See <ref id="debiansourcecontrolfiles">.
10163 Original source archive -
10165 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10171 This is a compressed (with <tt>gzip -9</tt>)
10172 <prgn>tar</prgn> file containing the source code from
10173 the upstream authors of the program.
10178 Debianisation diff -
10180 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10186 This is a unified context diff (<tt>diff -u</tt>)
10187 giving the changes which are required to turn the
10188 original source into the Debian source. These changes
10189 may only include editing and creating plain files.
10190 The permissions of files, the targets of symbolic
10191 links and the characteristics of special files or
10192 pipes may not be changed and no files may be removed
10197 All the directories in the diff must exist, except the
10198 <file>debian</file> subdirectory of the top of the source
10199 tree, which will be created by
10200 <prgn>dpkg-source</prgn> if necessary when unpacking.
10204 The <prgn>dpkg-source</prgn> program will
10205 automatically make the <file>debian/rules</file> file
10206 executable (see below).</p></item>
10211 If there is no original source code - for example, if the
10212 package is specially prepared for Debian or the Debian
10213 maintainer is the same as the upstream maintainer - the
10214 format is slightly different: then there is no diff, and the
10216 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10217 and preferably contains a directory named
10218 <file><var>package</var>-<var>version</var></file>.
10223 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10226 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10227 Debian source package. However, if it is not available it
10228 is possible to unpack a Debian source archive as follows:
10229 <enumlist compact="compact">
10232 Untar the tarfile, which will create a <file>.orig</file>
10236 <p>Rename the <file>.orig</file> directory to
10237 <file><var>package</var>-<var>version</var></file>.</p>
10241 Create the subdirectory <file>debian</file> at the top of
10242 the source tree.</p>
10244 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10246 <item><p>Untar the tarfile again if you want a copy of the original
10247 source code alongside the Debianised version.</p>
10252 It is not possible to generate a valid Debian source archive
10253 without using <prgn>dpkg-source</prgn>. In particular,
10254 attempting to use <prgn>diff</prgn> directly to generate the
10255 <file>.diff.gz</file> file will not work.
10259 <heading>Restrictions on objects in source packages</heading>
10262 The source package may not contain any hard links
10264 This is not currently detected when building source
10265 packages, but only when extracting
10269 Hard links may be permitted at some point in the
10270 future, but would require a fair amount of
10272 </footnote>, device special files, sockets or setuid or
10275 Setgid directories are allowed.
10280 The source packaging tools manage the changes between the
10281 original and Debianised source using <prgn>diff</prgn> and
10282 <prgn>patch</prgn>. Turning the original source tree as
10283 included in the <file>.orig.tar.gz</file> into the debianised
10284 source must not involve any changes which cannot be
10285 handled by these tools. Problematic changes which cause
10286 <prgn>dpkg-source</prgn> to halt with an error when
10287 building the source package are:
10288 <list compact="compact">
10289 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10291 <item><p>Changing the targets of symbolic links.</p>
10293 <item><p>Creating directories, other than <file>debian</file>.</p>
10295 <item><p>Changes to the contents of binary files.</p></item>
10296 </list> Changes which cause <prgn>dpkg-source</prgn> to
10297 print a warning but continue anyway are:
10298 <list compact="compact">
10301 Removing files, directories or symlinks.
10303 Renaming a file is not treated specially - it is
10304 seen as the removal of the old file (which
10305 generates a warning, but is otherwise ignored),
10306 and the creation of the new one.
10312 Changed text files which are missing the usual final
10313 newline (either in the original or the modified
10318 Changes which are not represented, but which are not detected by
10319 <prgn>dpkg-source</prgn>, are:
10320 <list compact="compact">
10321 <item><p>Changing the permissions of files (other than
10322 <file>debian/rules</file>) and directories.</p></item>
10327 The <file>debian</file> directory and <file>debian/rules</file>
10328 are handled specially by <prgn>dpkg-source</prgn> - before
10329 applying the changes it will create the <file>debian</file>
10330 directory, and afterwards it will make
10331 <file>debian/rules</file> world-executable.
10337 <appendix id="pkg-controlfields">
10338 <heading>Control files and their fields (from old Packaging Manual)</heading>
10341 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10342 data in a common format, known as control files. Binary and
10343 source packages have control data as do the <file>.changes</file>
10344 files which control the installation of uploaded files, and
10345 <prgn>dpkg</prgn>'s internal databases are in a similar
10350 <heading>Syntax of control files</heading>
10353 See <ref id="controlsyntax">.
10357 It is important to note that there are several fields which
10358 are optional as far as <prgn>dpkg</prgn> and the related
10359 tools are concerned, but which must appear in every Debian
10360 package, or whose omission may cause problems.
10365 <heading>List of fields</heading>
10368 See <ref id="controlfieldslist">.
10372 This section now contains only the fields that didn't belong
10373 to the Policy manual.
10376 <sect1 id="pkg-f-Filename">
10377 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10380 These fields in <tt>Packages</tt> files give the
10381 filename(s) of (the parts of) a package in the
10382 distribution directories, relative to the root of the
10383 Debian hierarchy. If the package has been split into
10384 several parts the parts are all listed in order, separated
10389 <sect1 id="pkg-f-Size">
10390 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10393 These fields in <file>Packages</file> files give the size (in
10394 bytes, expressed in decimal) and MD5 checksum of the
10395 file(s) which make(s) up a binary package in the
10396 distribution. If the package is split into several parts
10397 the values for the parts are listed in order, separated by
10402 <sect1 id="pkg-f-Status">
10403 <heading><tt>Status</tt></heading>
10406 This field in <prgn>dpkg</prgn>'s status file records
10407 whether the user wants a package installed, removed or
10408 left alone, whether it is broken (requiring
10409 re-installation) or not and what its current state on the
10410 system is. Each of these pieces of information is a
10415 <sect1 id="pkg-f-Config-Version">
10416 <heading><tt>Config-Version</tt></heading>
10419 If a package is not installed or not configured, this
10420 field in <prgn>dpkg</prgn>'s status file records the last
10421 version of the package which was successfully
10426 <sect1 id="pkg-f-Conffiles">
10427 <heading><tt>Conffiles</tt></heading>
10430 This field in <prgn>dpkg</prgn>'s status file contains
10431 information about the automatically-managed configuration
10432 files held by a package. This field should <em>not</em>
10433 appear anywhere in a package!
10438 <heading>Obsolete fields</heading>
10441 These are still recognized by <prgn>dpkg</prgn> but should
10442 not appear anywhere any more.
10444 <taglist compact="compact">
10446 <tag><tt>Revision</tt></tag>
10447 <tag><tt>Package-Revision</tt></tag>
10448 <tag><tt>Package_Revision</tt></tag>
10450 The Debian revision part of the package version was
10451 at one point in a separate control file field. This
10452 field went through several names.
10455 <tag><tt>Recommended</tt></tag>
10456 <item>Old name for <tt>Recommends</tt>.</item>
10458 <tag><tt>Optional</tt></tag>
10459 <item>Old name for <tt>Suggests</tt>.</item>
10461 <tag><tt>Class</tt></tag>
10462 <item>Old name for <tt>Priority</tt>.</item>
10471 <appendix id="pkg-conffiles">
10472 <heading>Configuration file handling (from old Packaging Manual)</heading>
10475 <prgn>dpkg</prgn> can do a certain amount of automatic
10476 handling of package configuration files.
10480 Whether this mechanism is appropriate depends on a number of
10481 factors, but basically there are two approaches to any
10482 particular configuration file.
10486 The easy method is to ship a best-effort configuration in the
10487 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10488 handle updates. If the user is unlikely to want to edit the
10489 file, but you need them to be able to without losing their
10490 changes, and a new package with a changed version of the file
10491 is only released infrequently, this is a good approach.
10495 The hard method is to build the configuration file from
10496 scratch in the <prgn>postinst</prgn> script, and to take the
10497 responsibility for fixing any mistakes made in earlier
10498 versions of the package automatically. This will be
10499 appropriate if the file is likely to need to be different on
10503 <sect><heading>Automatic handling of configuration files by
10508 A package may contain a control area file called
10509 <tt>conffiles</tt>. This file should be a list of filenames
10510 of configuration files needing automatic handling, separated
10511 by newlines. The filenames should be absolute pathnames,
10512 and the files referred to should actually exist in the
10517 When a package is upgraded <prgn>dpkg</prgn> will process
10518 the configuration files during the configuration stage,
10519 shortly before it runs the package's <prgn>postinst</prgn>
10524 For each file it checks to see whether the version of the
10525 file included in the package is the same as the one that was
10526 included in the last version of the package (the one that is
10527 being upgraded from); it also compares the version currently
10528 installed on the system with the one shipped with the last
10533 If neither the user nor the package maintainer has changed
10534 the file, it is left alone. If one or the other has changed
10535 their version, then the changed version is preferred - i.e.,
10536 if the user edits their file, but the package maintainer
10537 doesn't ship a different version, the user's changes will
10538 stay, silently, but if the maintainer ships a new version
10539 and the user hasn't edited it the new version will be
10540 installed (with an informative message). If both have
10541 changed their version the user is prompted about the problem
10542 and must resolve the differences themselves.
10546 The comparisons are done by calculating the MD5 message
10547 digests of the files, and storing the MD5 of the file as it
10548 was included in the most recent version of the package.
10552 When a package is installed for the first time
10553 <prgn>dpkg</prgn> will install the file that comes with it,
10554 unless that would mean overwriting a file already on the
10559 However, note that <prgn>dpkg</prgn> will <em>not</em>
10560 replace a conffile that was removed by the user (or by a
10561 script). This is necessary because with some programs a
10562 missing file produces an effect hard or impossible to
10563 achieve in another way, so that a missing file needs to be
10564 kept that way if the user did it.
10568 Note that a package should <em>not</em> modify a
10569 <prgn>dpkg</prgn>-handled conffile in its maintainer
10570 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10571 the user confusing and possibly dangerous options for
10572 conffile update when the package is upgraded.</p>
10575 <sect><heading>Fully-featured maintainer script configuration
10580 For files which contain site-specific information such as
10581 the hostname and networking details and so forth, it is
10582 better to create the file in the package's
10583 <prgn>postinst</prgn> script.
10587 This will typically involve examining the state of the rest
10588 of the system to determine values and other information, and
10589 may involve prompting the user for some information which
10590 can't be obtained some other way.
10594 When using this method there are a couple of important
10595 issues which should be considered:
10599 If you discover a bug in the program which generates the
10600 configuration file, or if the format of the file changes
10601 from one version to the next, you will have to arrange for
10602 the postinst script to do something sensible - usually this
10603 will mean editing the installed configuration file to remove
10604 the problem or change the syntax. You will have to do this
10605 very carefully, since the user may have changed the file,
10606 perhaps to fix the very problem that your script is trying
10607 to deal with - you will have to detect these situations and
10608 deal with them correctly.
10612 If you do go down this route it's probably a good idea to
10613 make the program that generates the configuration file(s) a
10614 separate program in <file>/usr/sbin</file>, by convention called
10615 <file><var>package</var>config</file> and then run that if
10616 appropriate from the post-installation script. The
10617 <tt><var>package</var>config</tt> program should not
10618 unquestioningly overwrite an existing configuration - if its
10619 mode of operation is geared towards setting up a package for
10620 the first time (rather than any arbitrary reconfiguration
10621 later) you should have it check whether the configuration
10622 already exists, and require a <tt>--force</tt> flag to
10623 overwrite it.</p></sect>
10626 <appendix id="pkg-alternatives"><heading>Alternative versions of
10627 an interface - <prgn>update-alternatives</prgn> (from old
10632 When several packages all provide different versions of the
10633 same program or file it is useful to have the system select a
10634 default, but to allow the system administrator to change it
10635 and have their decisions respected.
10639 For example, there are several versions of the <prgn>vi</prgn>
10640 editor, and there is no reason to prevent all of them from
10641 being installed at once, each under their own name
10642 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10643 Nevertheless it is desirable to have the name <tt>vi</tt>
10644 refer to something, at least by default.
10648 If all the packages involved cooperate, this can be done with
10649 <prgn>update-alternatives</prgn>.
10653 Each package provides its own version under its own name, and
10654 calls <prgn>update-alternatives</prgn> in its postinst to
10655 register its version (and again in its prerm to deregister
10660 See the man page <manref name="update-alternatives"
10661 section="8"> for details.
10665 If <prgn>update-alternatives</prgn> does not seem appropriate
10666 you may wish to consider using diversions instead.</p>
10669 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10670 package's version of a file (from old Packaging Manual)
10674 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10675 when it reinstalls the package it belongs to, and to have it
10676 put the file from the package somewhere else instead.
10680 This can be used locally to override a package's version of a
10681 file, or by one package to override another's version (or
10682 provide a wrapper for it).
10686 Before deciding to use a diversion, read <ref
10687 id="pkg-alternatives"> to see if you really want a diversion
10688 rather than several alternative versions of a program.
10692 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10693 and updated by a special program <prgn>dpkg-divert</prgn>.
10694 Please see <manref name="dpkg-divert" section="8"> for full
10695 details of its operation.
10699 When a package wishes to divert a file from another, it should
10700 call <prgn>dpkg-divert</prgn> in its preinst to add the
10701 diversion and rename the existing file. For example,
10702 supposing that a <prgn>smailwrapper</prgn> package wishes to
10703 install a wrapper around <file>/usr/sbin/smail</file>:
10705 dpkg-divert --package smailwrapper --add --rename \
10706 --divert /usr/sbin/smail.real /usr/sbin/smail
10707 </example> The <tt>--package smailwrapper</tt> ensures that
10708 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
10709 can bypass the diversion and get installed as the true version.
10710 It's safe to add the diversion unconditionally on upgrades since
10711 it will be left unchanged if it already exists, but
10712 <prgn>dpkg-divert</prgn> will display a message. To suppress that
10713 message, make the command conditional on the version from which
10714 the package is being upgraded:
10716 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
10717 dpkg-divert --package smailwrapper --add --rename \
10718 --divert /usr/sbin/smail.real /usr/sbin/smail
10720 </example> where <tt>1.0-2</tt> is the version at which the
10721 diversion was first added to the package. Running the command
10722 during abort-upgrade is pointless but harmless.
10726 The postrm has to do the reverse:
10728 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
10729 dpkg-divert --package smailwrapper --remove --rename \
10730 --divert /usr/sbin/smail.real /usr/sbin/smail
10732 </example> If the diversion was added at a particular version, the
10733 postrm should also handle the failure case of upgrading from an
10734 older version (unless the older version is so old that direct
10735 upgrades are no longer supported):
10737 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
10738 dpkg-divert --package smailwrapper --remove --rename \
10739 --divert /usr/sbin/smail.real /usr/sbin/smail
10741 </example> where <tt>1.02-2</tt> is the version at which the
10742 diversion was first added to the package. The postrm should not
10743 remove the diversion on upgrades both because there's no reason to
10744 remove the diversion only to immediately re-add it and since the
10745 postrm of the old package is run after unpacking so the removal of
10746 the diversion will fail.
10750 Do not attempt to divert a file which is vitally important for
10751 the system's operation - when using <prgn>dpkg-divert</prgn>
10752 there is a time, after it has been diverted but before
10753 <prgn>dpkg</prgn> has installed the new version, when the file
10754 does not exist.</p>
10759 <!-- Local variables: -->
10760 <!-- indent-tabs-mode: t -->
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