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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 unpacked
1058 <em>and</em> configured before it can be unpacked. 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
1858 for 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>
1861 is not <tt>all</tt>).
1862 Similarly, the <tt>build-indep</tt> target, if
1863 provided, should perform all the configuration and
1864 compilation required for producing all
1865 architecture-independent binary packages
1866 (those packages for which the body of the
1867 <tt>Architecture</tt> field in <tt>debian/control</tt>
1869 The <tt>build</tt> target should depend on those of the
1870 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1871 are provided in the rules file.
1875 If one or both of the targets <tt>build-arch</tt> and
1876 <tt>build-indep</tt> are not provided, then invoking
1877 <file>debian/rules</file> with one of the not-provided
1878 targets as arguments should produce a exit status code
1879 of 2. Usually this is provided automatically by make
1880 if the target is missing.
1884 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1885 must not do anything that might require root privilege.
1889 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1890 <tt>binary-indep</tt>
1894 The <tt>binary</tt> target must be all that is
1895 necessary for the user to build the binary package(s)
1896 produced from this source package. It is
1897 split into two parts: <prgn>binary-arch</prgn> builds
1898 the binary packages which are specific to a particular
1899 architecture, and <tt>binary-indep</tt> builds
1900 those which are not.
1903 <tt>binary</tt> may be (and commonly is) a target with
1904 no commands which simply depends on
1905 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1908 Both <tt>binary-*</tt> targets should depend on the
1909 <tt>build</tt> target, or on the appropriate
1910 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1911 provided, so that the package is built if it has not
1912 been already. It should then create the relevant
1913 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1914 make their control files and <prgn>dpkg-deb</prgn> to
1915 build them and place them in the parent of the top
1920 Both the <tt>binary-arch</tt> and
1921 <tt>binary-indep</tt> targets <em>must</em> exist.
1922 If one of them has nothing to do (which will always be
1923 the case if the source generates only a single binary
1924 package, whether architecture-dependent or not), it
1925 must still exist and must always succeed.
1929 The <tt>binary</tt> targets must be invoked as
1931 The <prgn>fakeroot</prgn> package often allows one
1932 to build a package correctly even without being
1938 <tag><tt>clean</tt></tag>
1941 This must undo any effects that the <tt>build</tt>
1942 and <tt>binary</tt> targets may have had, except
1943 that it should leave alone any output files created in
1944 the parent directory by a run of a <tt>binary</tt>
1949 If a <tt>build</tt> file is touched at the end of
1950 the <tt>build</tt> target, as suggested above, it
1951 should be removed as the first action that
1952 <tt>clean</tt> performs, so that running
1953 <tt>build</tt> again after an interrupted
1954 <tt>clean</tt> doesn't think that everything is
1959 The <tt>clean</tt> target may need to be
1960 invoked as root if <tt>binary</tt> has been
1961 invoked since the last <tt>clean</tt>, or if
1962 <tt>build</tt> has been invoked as root (since
1963 <tt>build</tt> may create directories, for
1968 <tag><tt>get-orig-source</tt> (optional)</tag>
1971 This target fetches the most recent version of the
1972 original source package from a canonical archive site
1973 (via FTP or WWW, for example), does any necessary
1974 rearrangement to turn it into the original source
1975 tar file format described below, and leaves it in the
1980 This target may be invoked in any directory, and
1981 should take care to clean up any temporary files it
1986 This target is optional, but providing it if
1987 possible is a good idea.
1991 <tag><tt>patch</tt> (optional)</tag>
1994 This target performs whatever additional actions are
1995 required to make the source ready for editing (unpacking
1996 additional upstream archives, applying patches, etc.).
1997 It is recommended to be implemented for any package where
1998 <tt>dpkg-source -x</tt> does not result in source ready
1999 for additional modification. See
2000 <ref id="readmesource">.
2006 The <tt>build</tt>, <tt>binary</tt> and
2007 <tt>clean</tt> targets must be invoked with the current
2008 directory being the package's top-level directory.
2013 Additional targets may exist in <file>debian/rules</file>,
2014 either as published or undocumented interfaces or for the
2015 package's internal use.
2019 The architectures we build on and build for are determined
2020 by <prgn>make</prgn> variables using the utility
2021 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
2022 You can determine the
2023 Debian architecture and the GNU style architecture
2024 specification string for the build machine (the machine type
2025 we are building on) as well as for the host machine (the
2026 machine type we are building for). Here is a list of
2027 supported <prgn>make</prgn> variables:
2028 <list compact="compact">
2030 <tt>DEB_*_ARCH</tt> (the Debian architecture)
2033 <tt>DEB_*_ARCH_CPU</tt> (the Debian CPU name)
2036 <tt>DEB_*_ARCH_OS</tt> (the Debian System name)
2039 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2040 specification string)
2043 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2044 <tt>DEB_*_GNU_TYPE</tt>)
2047 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2048 <tt>DEB_*_GNU_TYPE</tt>)
2050 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2051 the build machine or <tt>HOST</tt> for specification of the
2056 Backward compatibility can be provided in the rules file
2057 by setting the needed variables to suitable default
2058 values; please refer to the documentation of
2059 <prgn>dpkg-architecture</prgn> for details.
2063 It is important to understand that the <tt>DEB_*_ARCH</tt>
2064 string only determines which Debian architecture we are
2065 building on or for. It should not be used to get the CPU
2066 or system information; the <tt>DEB_*_ARCH_CPU</tt> and
2067 <tt>DEB_*_ARCH_OS</tt> variables should be used for that.
2068 GNU style variables should generally only be used with upstream
2072 <sect1 id="debianrules-options">
2073 <heading><file>debian/rules</file> and
2074 <tt>DEB_BUILD_OPTIONS</tt></heading>
2077 Supporting the standardized environment variable
2078 <tt>DEB_BUILD_OPTIONS</tt> is recommended. This variable can
2079 contain several flags to change how a package is compiled and
2080 built. Each flag must be in the form <var>flag</var> or
2081 <var>flag</var>=<var>options</var>. If multiple flags are
2082 given, they must be separated by whitespace.<footnote>
2083 Some packages support any delimiter, but whitespace is the
2084 easiest to parse inside a makefile and avoids ambiguity with
2085 flag values that contain commas.
2087 <var>flag</var> must start with a lowercase letter
2088 (<tt>a-z</tt>) and consist only of lowercase letters,
2089 numbers (<tt>0-9</tt>), and the characters
2090 <tt>-</tt> and <tt>_</tt> (hyphen and underscore).
2091 <var>options</var> must not contain whitespace. The same
2092 tag should not be given multiple times with conflicting
2093 values. Package maintainers may assume that
2094 <tt>DEB_BUILD_OPTIONS</tt> will not contain conflicting tags.
2098 The meaning of the following tags has been standardized:
2102 This tag says to not run any build-time test suite
2103 provided by the package.
2107 The presence of this tag means that the package should
2108 be compiled with a minimum of optimization. For C
2109 programs, it is best to add <tt>-O0</tt> to
2110 <tt>CFLAGS</tt> (although this is usually the default).
2111 Some programs might fail to build or run at this level
2112 of optimization; it may be necessary to use
2113 <tt>-O1</tt>, for example.
2117 This tag means that the debugging symbols should not be
2118 stripped from the binary during installation, so that
2119 debugging information may be included in the package.
2121 <tag>parallel=n</tag>
2123 This tag means that the package should be built using up
2124 to <tt>n</tt> parallel processes if the package build
2125 system supports this.<footnote>
2126 Packages built with <tt>make</tt> can often implement
2127 this by passing the <tt>-j</tt><var>n</var> option to
2130 If the package build system does not support parallel
2131 builds, this string must be ignored. If the package
2132 build system only supports a lower level of concurrency
2133 than <var>n</var>, the package should be built using as
2134 many parallel processes as the package build system
2135 supports. It is up to the package maintainer to decide
2136 whether the package build times are long enough and the
2137 package build system is robust enough to make supporting
2138 parallel builds worthwhile.
2144 Unknown flags must be ignored by <file>debian/rules</file>.
2148 The following makefile snippet is an example of how one may
2149 implement the build options; you will probably have to
2150 massage this example in order to make it work for your
2152 <example compact="compact">
2155 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
2156 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
2157 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
2158 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
2160 ifneq (,$(filter noopt,$(DEB_BUILD_OPTIONS)))
2165 ifeq (,$(filter nostrip,$(DEB_BUILD_OPTIONS)))
2166 INSTALL_PROGRAM += -s
2168 ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2169 NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2170 MAKEFLAGS += -j$(NUMJOBS)
2175 ifeq (,$(filter nocheck,$(DEB_BUILD_OPTIONS)))
2176 # Code to run the package test suite.
2183 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2184 <sect id="substvars">
2185 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2188 When <prgn>dpkg-gencontrol</prgn>,
2189 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2190 generate control files they perform variable substitutions
2191 on their output just before writing it. Variable
2192 substitutions have the form <tt>${<var>variable</var>}</tt>.
2193 The optional file <file>debian/substvars</file> contains
2194 variable substitutions to be used; variables can also be set
2195 directly from <file>debian/rules</file> using the <tt>-V</tt>
2196 option to the source packaging commands, and certain
2197 predefined variables are also available.
2201 The <file>debian/substvars</file> file is usually generated and
2202 modified dynamically by <file>debian/rules</file> targets, in
2203 which case it must be removed by the <tt>clean</tt> target.
2207 See <manref name="deb-substvars" section="5"> for full
2208 details about source variable substitutions, including the
2209 format of <file>debian/substvars</file>.</p>
2212 <sect id="debianwatch">
2213 <heading>Optional upstream source location: <file>debian/watch</file></heading>
2216 This is an optional, recommended control file for the
2217 <tt>uscan</tt> utility which defines how to automatically
2218 scan ftp or http sites for newly available updates of the
2219 package. This is used by <url id="
2220 http://dehs.alioth.debian.org/"> and other Debian QA tools
2221 to help with quality control and maintenance of the
2222 distribution as a whole.
2227 <sect id="debianfiles">
2228 <heading>Generated files list: <file>debian/files</file></heading>
2231 This file is not a permanent part of the source tree; it
2232 is used while building packages to record which files are
2233 being generated. <prgn>dpkg-genchanges</prgn> uses it
2234 when it generates a <file>.changes</file> file.
2238 It should not exist in a shipped source package, and so it
2239 (and any backup files or temporary files such as
2240 <file>files.new</file><footnote>
2241 <file>files.new</file> is used as a temporary file by
2242 <prgn>dpkg-gencontrol</prgn> and
2243 <prgn>dpkg-distaddfile</prgn> - they write a new
2244 version of <tt>files</tt> here before renaming it,
2245 to avoid leaving a corrupted copy if an error
2247 </footnote>) should be removed by the
2248 <tt>clean</tt> target. It may also be wise to
2249 ensure a fresh start by emptying or removing it at the
2250 start of the <tt>binary</tt> target.
2254 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2255 package, it adds an entry to <file>debian/files</file> for the
2256 <file>.deb</file> file that will be created when <tt>dpkg-deb
2257 --build</tt> is run for that binary package. So for most
2258 packages all that needs to be done with this file is to
2259 delete it in the <tt>clean</tt> target.
2263 If a package upload includes files besides the source
2264 package and any binary packages whose control files were
2265 made with <prgn>dpkg-gencontrol</prgn> then they should be
2266 placed in the parent of the package's top-level directory
2267 and <prgn>dpkg-distaddfile</prgn> should be called to add
2268 the file to the list in <file>debian/files</file>.</p>
2271 <sect id="embeddedfiles">
2272 <heading>Convenience copies of code</heading>
2275 Some software packages include in their distribution convenience
2276 copies of code from other software packages, generally so that
2277 users compiling from source don't have to download multiple
2278 packages. Debian packages should not make use of these
2279 convenience copies unless the included package is explicitly
2280 intended to be used in this way.<footnote>
2281 For example, parts of the GNU build system work like this.
2283 If the included code is already in the Debian archive in the
2284 form of a library, the Debian packaging should ensure that
2285 binary packages reference the libraries already in Debian and
2286 the convenience copy is not used. If the included code is not
2287 already in Debian, it should be packaged separately as a
2288 prerequisite if possible.
2290 Having multiple copies of the same code in Debian is
2291 inefficient, often creates either static linking or shared
2292 library conflicts, and, most importantly, increases the
2293 difficulty of handling security vulnerabilities in the
2299 <sect id="readmesource">
2300 <heading>Source package handling:
2301 <file>debian/README.source</file></heading>
2304 If running <prgn>dpkg-source -x</prgn> on a source package
2305 doesn't produce the source of the package, ready for editing,
2306 and allow one to make changes and run
2307 <prgn>dpkg-buildpackage</prgn> to produce a modified package
2308 without taking any additional steps, creating a
2309 <file>debian/README.source</file> documentation file is
2310 recommended. This file should explain how to do all of the
2313 <item>Generate the fully patched source, in a form ready for
2314 editing, that would be built to create Debian
2315 packages. Doing this with a <tt>patch</tt> target in
2316 <file>debian/rules</file> is recommended; see
2317 <ref id="debianrules">.</item>
2318 <item>Modify the source and save those modifications so that
2319 they will be applied when building the package.</item>
2320 <item>Remove source modifications that are currently being
2321 applied when building the package.</item>
2322 <item>Optionally, document what steps are necessary to
2323 upgrade the Debian source package to a new upstream version,
2324 if applicable.</item>
2326 This explanation should include specific commands and mention
2327 any additional required Debian packages. It should not assume
2328 familiarity with any specific Debian packaging system or patch
2333 This explanation may refer to a documentation file installed by
2334 one of the package's build dependencies provided that the
2335 referenced documentation clearly explains these tasks and is not
2336 a general reference manual.
2340 <file>debian/README.source</file> may also include any other
2341 information that would be helpful to someone modifying the
2342 source package. Even if the package doesn't fit the above
2343 description, maintainers are encouraged to document in a
2344 <file>debian/README.source</file> file any source package with a
2345 particularly complex or unintuitive source layout or build
2346 system (for example, a package that builds the same source
2347 multiple times to generate different binary packages).
2353 <chapt id="controlfields">
2354 <heading>Control files and their fields</heading>
2357 The package management system manipulates data represented in
2358 a common format, known as <em>control data</em>, stored in
2359 <em>control files</em>.
2360 Control files are used for source packages, binary packages and
2361 the <file>.changes</file> files which control the installation
2362 of uploaded files<footnote>
2363 <prgn>dpkg</prgn>'s internal databases are in a similar
2368 <sect id="controlsyntax">
2369 <heading>Syntax of control files</heading>
2372 A control file consists of one or more paragraphs of
2374 The paragraphs are also sometimes referred to as stanzas.
2376 The paragraphs are separated by blank lines. Some control
2377 files allow only one paragraph; others allow several, in
2378 which case each paragraph usually refers to a different
2379 package. (For example, in source packages, the first
2380 paragraph refers to the source package, and later paragraphs
2381 refer to binary packages generated from the source.)
2385 Each paragraph consists of a series of data fields; each
2386 field consists of the field name, followed by a colon and
2387 then the data/value associated with that field. It ends at
2388 the end of the (logical) line. Horizontal whitespace
2389 (spaces and tabs) may occur immediately before or after the
2390 value and is ignored there; it is conventional to put a
2391 single space after the colon. For example, a field might
2393 <example compact="compact">
2396 the field name is <tt>Package</tt> and the field value
2401 Many fields' values may span several lines; in this case
2402 each continuation line must start with a space or a tab.
2403 Any trailing spaces or tabs at the end of individual
2404 lines of a field value are ignored.
2408 In fields where it is specified that lines may not wrap,
2409 only a single line of data is allowed and whitespace is not
2410 significant in a field body. Whitespace must not appear
2411 inside names (of packages, architectures, files or anything
2412 else) or version numbers, or between the characters of
2413 multi-character version relationships.
2417 Field names are not case-sensitive, but it is usual to
2418 capitalize the field names using mixed case as shown below.
2419 Field values are case-sensitive unless the description of the
2420 field says otherwise.
2424 Blank lines, or lines consisting only of spaces and tabs,
2425 are not allowed within field values or between fields - that
2426 would mean a new paragraph.
2430 All control files must be encoded in UTF-8.
2434 <sect id="sourcecontrolfiles">
2435 <heading>Source package control files -- <file>debian/control</file></heading>
2438 The <file>debian/control</file> file contains the most vital
2439 (and version-independent) information about the source package
2440 and about the binary packages it creates.
2444 The first paragraph of the control file contains information about
2445 the source package in general. The subsequent sets each describe a
2446 binary package that the source tree builds.
2450 The fields in the general paragraph (the first one, for the source
2453 <list compact="compact">
2454 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2455 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2456 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2457 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2458 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2459 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2460 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2461 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2466 The fields in the binary package paragraphs are:
2468 <list compact="compact">
2469 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2470 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2471 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2472 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2473 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2474 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2475 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2476 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2481 The syntax and semantics of the fields are described below.
2487 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2488 generate control files for binary packages (see below), by
2489 <prgn>dpkg-genchanges</prgn> to generate the
2490 <tt>.changes</tt> file to accompany the upload, and by
2491 <prgn>dpkg-source</prgn> when it creates the
2492 <file>.dsc</file> source control file as part of a source
2493 archive. Many fields are permitted to span multiple lines in
2494 <file>debian/control</file> but not in any other control
2495 file. These tools are responsible for removing the line
2496 breaks from such fields when using fields from
2497 <file>debian/control</file> to generate other control files.
2501 The fields here may contain variable references - their
2502 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2503 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2504 when they generate output control files.
2505 See <ref id="substvars"> for details.
2509 In addition to the control file syntax described <qref
2510 id="controlsyntax">above</qref>, this file may also contain
2511 comment lines starting with <tt>#</tt> without any preceding
2512 whitespace. All such lines are ignored, even in the middle of
2513 continuation lines for a multiline field, and do not end a
2519 <sect id="binarycontrolfiles">
2520 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2523 The <file>DEBIAN/control</file> file contains the most vital
2524 (and version-dependent) information about a binary package.
2528 The fields in this file are:
2530 <list compact="compact">
2531 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2532 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2533 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2534 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2535 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2536 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2537 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2538 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2539 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2540 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2541 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2542 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2547 <sect id="debiansourcecontrolfiles">
2548 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2551 This file contains a series of fields, identified and
2552 separated just like the fields in the control file of
2553 a binary package. The fields are listed below; their
2554 syntax is described above, in <ref id="pkg-controlfields">.
2556 <list compact="compact">
2557 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2558 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2559 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2560 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2561 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2562 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2563 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2564 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2565 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2566 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2567 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2572 The source package control file is generated by
2573 <prgn>dpkg-source</prgn> when it builds the source
2574 archive, from other files in the source package,
2575 described above. When unpacking, it is checked against
2576 the files and directories in the other parts of the
2582 <sect id="debianchangesfiles">
2583 <heading>Debian changes files -- <file>.changes</file></heading>
2586 The .changes files are used by the Debian archive maintenance
2587 software to process updates to packages. They contain one
2588 paragraph which contains information from the
2589 <tt>debian/control</tt> file and other data about the
2590 source package gathered via <tt>debian/changelog</tt>
2591 and <tt>debian/rules</tt>.
2595 The fields in this file are:
2597 <list compact="compact">
2598 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2599 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2600 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2601 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2602 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2603 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2604 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2605 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2606 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2607 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2608 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2609 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2610 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2611 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2616 <sect id="controlfieldslist">
2617 <heading>List of fields</heading>
2619 <sect1 id="f-Source">
2620 <heading><tt>Source</tt></heading>
2623 This field identifies the source package name.
2627 In <file>debian/control</file> or a <file>.dsc</file> file,
2628 this field must contain only the name of the source package.
2632 In a binary package control file or a <file>.changes</file>
2633 file, the source package name may be followed by a version
2634 number in parentheses<footnote>
2635 It is customary to leave a space after the package name
2636 if a version number is specified.
2638 This version number may be omitted (and is, by
2639 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2640 the <tt>Version</tt> field of the binary package in
2641 question. The field itself may be omitted from a binary
2642 package control file when the source package has the same
2643 name and version as the binary package.
2647 Package names (both source and binary,
2648 see <ref id="f-Package">) must consist only of lower case
2649 letters (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus
2650 (<tt>+</tt>) and minus (<tt>-</tt>) signs, and periods
2651 (<tt>.</tt>). They must be at least two characters long and
2652 must start with an alphanumeric character.
2656 <sect1 id="f-Maintainer">
2657 <heading><tt>Maintainer</tt></heading>
2660 The package maintainer's name and email address. The name
2661 should come first, then the email address inside angle
2662 brackets <tt><></tt> (in RFC822 format).
2666 If the maintainer's name contains a full stop then the
2667 whole field will not work directly as an email address due
2668 to a misfeature in the syntax specified in RFC822; a
2669 program using this field as an address must check for this
2670 and correct the problem if necessary (for example by
2671 putting the name in round brackets and moving it to the
2672 end, and bringing the email address forward).
2676 <sect1 id="f-Uploaders">
2677 <heading><tt>Uploaders</tt></heading>
2680 List of the names and email addresses of co-maintainers of
2681 the package, if any. If the package has other maintainers
2682 beside the one named in the
2683 <qref id="f-Maintainer">Maintainer field</qref>, their
2684 names and email addresses should be listed here. The
2685 format is the same as that of the Maintainer tag, and
2686 multiple entries should be comma separated. Currently,
2687 this field is restricted to a single line of data. This
2688 is an optional field.
2691 Any parser that interprets the Uploaders field in
2692 <file>debian/control</file> must permit it to span multiple
2693 lines. Line breaks in an Uploaders field that spans multiple
2694 lines are not significant and the semantics of the field are
2695 the same as if the line breaks had not been present.
2699 <sect1 id="f-Changed-By">
2700 <heading><tt>Changed-By</tt></heading>
2703 The name and email address of the person who changed the
2704 said package. Usually the name of the maintainer.
2705 All the rules for the Maintainer field apply here, too.
2709 <sect1 id="f-Section">
2710 <heading><tt>Section</tt></heading>
2713 This field specifies an application area into which the package
2714 has been classified. See <ref id="subsections">.
2718 When it appears in the <file>debian/control</file> file,
2719 it gives the value for the subfield of the same name in
2720 the <tt>Files</tt> field of the <file>.changes</file> file.
2721 It also gives the default for the same field in the binary
2726 <sect1 id="f-Priority">
2727 <heading><tt>Priority</tt></heading>
2730 This field represents how important it is that the user
2731 have the package installed. See <ref id="priorities">.
2735 When it appears in the <file>debian/control</file> file,
2736 it gives the value for the subfield of the same name in
2737 the <tt>Files</tt> field of the <file>.changes</file> file.
2738 It also gives the default for the same field in the binary
2743 <sect1 id="f-Package">
2744 <heading><tt>Package</tt></heading>
2747 The name of the binary package.
2751 Binary package names must follow the same syntax and
2752 restrictions as source package names. See <ref id="f-Source">
2757 <sect1 id="f-Architecture">
2758 <heading><tt>Architecture</tt></heading>
2761 Depending on context and the control file used, the
2762 <tt>Architecture</tt> field can include the following sets of
2766 A unique single word identifying a Debian machine
2767 architecture as described in <ref id="arch-spec">.
2770 An architecture wildcard identifying a set of Debian
2771 machine architectures, see <ref id="arch-wildcard-spec">.
2772 <tt>any</tt> matches all Debian machine architectures
2773 and is the most frequently used.
2776 <tt>all</tt>, which indicates an
2777 architecture-independent package.
2780 <tt>source</tt>, which indicates a source package.
2786 In the main <file>debian/control</file> file in the source
2787 package, this field may contain the special
2788 value <tt>all</tt>, the special architecture
2789 wildcard <tt>any</tt>, or a list of specific and wildcard
2790 architectures separated by spaces. If <tt>all</tt>
2791 or <tt>any</tt> appears, that value must be the entire
2792 contents of the field. Most packages will use
2793 either <tt>all</tt> or <tt>any</tt>.
2797 Specifying a specific list of architectures indicates that the
2798 source will build an architecture-dependent package only on
2799 architectures included in the list. Specifying a list of
2800 architecture wildcards indicates that the source will build an
2801 architecture-dependent package on only those architectures
2802 that match any of the specified architecture wildcards.
2803 Specifying a list of architectures or architecture wildcards
2804 other than <tt>any</tt> is for the minority of cases where a
2805 program is not portable or is not useful on some
2806 architectures. Where possible, the program should be made
2811 In the source package control file <file>.dsc</file>, this
2812 field may contain either the architecture
2813 wildcard <tt>any</tt> or a list of architectures and
2814 architecture wildcards separated by spaces. If a list is
2815 given, it may include (or consist solely of) the special
2816 value <tt>all</tt>. In other words, in <file>.dsc</file>
2817 files unlike the <file>debian/control</file>, <tt>all</tt> may
2818 occur in combination with specific architectures.
2819 The <tt>Architecture</tt> field in the source package control
2820 file <file>.dsc</file> is generally constructed from
2821 the <tt>Architecture</tt> fields in
2822 the <file>debian/control</file> in the source package.
2826 Specifying <tt>any</tt> indicates that the source package
2827 isn't dependent on any particular architecture and should
2828 compile fine on any one. The produced binary package(s)
2829 will either be specific to whatever the current build
2830 architecture is or will be architecture-independent.
2834 Specifying only <tt>all</tt> indicates that the source package
2835 will only build architecture-independent packages. If this is
2836 the case, <tt>all</tt> must be used rather than <tt>any</tt>;
2837 <tt>any</tt> implies that the source package will build at
2838 least one architecture-dependent package.
2842 Specifying a list of architectures or architecture wildcards
2843 indicates that the source will build an architecture-dependent
2844 package, and will only work correctly on the listed or
2845 matching architectures. If the source package also builds at
2846 least one architecture-independent package, <tt>all</tt> will
2847 also be included in the list.
2851 In a <file>.changes</file> file, the <tt>Architecture</tt>
2852 field lists the architecture(s) of the package(s) currently
2853 being uploaded. This will be a list; if the source for the
2854 package is also being uploaded, the special
2855 entry <tt>source</tt> is also present. <tt>all</tt> will be
2856 present if any architecture-independent packages are being
2857 uploaded. Architecture wildcards such as <tt>any</tt> must
2858 never occur in the <tt>Architecture</tt> field in
2859 the <file>.changes</file> file.
2863 See <ref id="debianrules"> for information on how to get
2864 the architecture for the build process.
2868 <sect1 id="f-Essential">
2869 <heading><tt>Essential</tt></heading>
2872 This is a boolean field which may occur only in the
2873 control file of a binary package or in a per-package fields
2874 paragraph of a main source control data file.
2878 If set to <tt>yes</tt> then the package management system
2879 will refuse to remove the package (upgrading and replacing
2880 it is still possible). The other possible value is <tt>no</tt>,
2881 which is the same as not having the field at all.
2886 <heading>Package interrelationship fields:
2887 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2888 <tt>Recommends</tt>, <tt>Suggests</tt>,
2889 <tt>Breaks</tt>, <tt>Conflicts</tt>,
2890 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2894 These fields describe the package's relationships with
2895 other packages. Their syntax and semantics are described
2896 in <ref id="relationships">.</p>
2899 <sect1 id="f-Standards-Version">
2900 <heading><tt>Standards-Version</tt></heading>
2903 The most recent version of the standards (the policy
2904 manual and associated texts) with which the package
2909 The version number has four components: major and minor
2910 version number and major and minor patch level. When the
2911 standards change in a way that requires every package to
2912 change the major number will be changed. Significant
2913 changes that will require work in many packages will be
2914 signaled by a change to the minor number. The major patch
2915 level will be changed for any change to the meaning of the
2916 standards, however small; the minor patch level will be
2917 changed when only cosmetic, typographical or other edits
2918 are made which neither change the meaning of the document
2919 nor affect the contents of packages.
2923 Thus only the first three components of the policy version
2924 are significant in the <em>Standards-Version</em> control
2925 field, and so either these three components or all four
2926 components may be specified.<footnote>
2927 In the past, people specified the full version number
2928 in the Standards-Version field, for example "2.3.0.0".
2929 Since minor patch-level changes don't introduce new
2930 policy, it was thought it would be better to relax
2931 policy and only require the first 3 components to be
2932 specified, in this example "2.3.0". All four
2933 components may still be used if someone wishes to do so.
2939 <sect1 id="f-Version">
2940 <heading><tt>Version</tt></heading>
2943 The version number of a package. The format is:
2944 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2948 The three components here are:
2950 <tag><var>epoch</var></tag>
2953 This is a single (generally small) unsigned integer. It
2954 may be omitted, in which case zero is assumed. If it is
2955 omitted then the <var>upstream_version</var> may not
2960 It is provided to allow mistakes in the version numbers
2961 of older versions of a package, and also a package's
2962 previous version numbering schemes, to be left behind.
2966 <tag><var>upstream_version</var></tag>
2969 This is the main part of the version number. It is
2970 usually the version number of the original ("upstream")
2971 package from which the <file>.deb</file> file has been made,
2972 if this is applicable. Usually this will be in the same
2973 format as that specified by the upstream author(s);
2974 however, it may need to be reformatted to fit into the
2975 package management system's format and comparison
2980 The comparison behavior of the package management system
2981 with respect to the <var>upstream_version</var> is
2982 described below. The <var>upstream_version</var>
2983 portion of the version number is mandatory.
2987 The <var>upstream_version</var> may contain only
2988 alphanumerics<footnote>
2989 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2991 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2992 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
2993 tilde) and should start with a digit. If there is no
2994 <var>debian_revision</var> then hyphens are not allowed;
2995 if there is no <var>epoch</var> then colons are not
3000 <tag><var>debian_revision</var></tag>
3003 This part of the version number specifies the version of
3004 the Debian package based on the upstream version. It
3005 may contain only alphanumerics and the characters
3006 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
3007 tilde) and is compared in the same way as the
3008 <var>upstream_version</var> is.
3012 It is optional; if it isn't present then the
3013 <var>upstream_version</var> may not contain a hyphen.
3014 This format represents the case where a piece of
3015 software was written specifically to be turned into a
3016 Debian package, and so there is only one "debianisation"
3017 of it and therefore no revision indication is required.
3021 It is conventional to restart the
3022 <var>debian_revision</var> at <tt>1</tt> each time the
3023 <var>upstream_version</var> is increased.
3027 The package management system will break the version
3028 number apart at the last hyphen in the string (if there
3029 is one) to determine the <var>upstream_version</var> and
3030 <var>debian_revision</var>. The absence of a
3031 <var>debian_revision</var> is equivalent to a
3032 <var>debian_revision</var> of <tt>0</tt>.
3039 When comparing two version numbers, first the <var>epoch</var>
3040 of each are compared, then the <var>upstream_version</var> if
3041 <var>epoch</var> is equal, and then <var>debian_revision</var>
3042 if <var>upstream_version</var> is also equal.
3043 <var>epoch</var> is compared numerically. The
3044 <var>upstream_version</var> and <var>debian_revision</var>
3045 parts are compared by the package management system using the
3046 following algorithm:
3050 The strings are compared from left to right.
3054 First the initial part of each string consisting entirely of
3055 non-digit characters is determined. These two parts (one of
3056 which may be empty) are compared lexically. If a difference
3057 is found it is returned. The lexical comparison is a
3058 comparison of ASCII values modified so that all the letters
3059 sort earlier than all the non-letters and so that a tilde
3060 sorts before anything, even the end of a part. For example,
3061 the following parts are in sorted order from earliest to
3062 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
3063 <tt>a</tt>.<footnote>
3064 One common use of <tt>~</tt> is for upstream pre-releases.
3065 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
3066 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
3071 Then the initial part of the remainder of each string which
3072 consists entirely of digit characters is determined. The
3073 numerical values of these two parts are compared, and any
3074 difference found is returned as the result of the comparison.
3075 For these purposes an empty string (which can only occur at
3076 the end of one or both version strings being compared) counts
3081 These two steps (comparing and removing initial non-digit
3082 strings and initial digit strings) are repeated until a
3083 difference is found or both strings are exhausted.
3087 Note that the purpose of epochs is to allow us to leave behind
3088 mistakes in version numbering, and to cope with situations
3089 where the version numbering scheme changes. It is
3090 <em>not</em> intended to cope with version numbers containing
3091 strings of letters which the package management system cannot
3092 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
3093 silly orderings.<footnote>
3094 The author of this manual has heard of a package whose
3095 versions went <tt>1.1</tt>, <tt>1.2</tt>, <tt>1.3</tt>,
3096 <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>, <tt>2</tt> and so
3102 <sect1 id="f-Description">
3103 <heading><tt>Description</tt></heading>
3106 In a source or binary control file, the <tt>Description</tt>
3107 field contains a description of the binary package, consisting
3108 of two parts, the synopsis or the short description, and the
3109 long description. The field's format is as follows:
3114 Description: <single line synopsis>
3115 <extended description over several lines>
3120 The lines in the extended description can have these formats:
3126 Those starting with a single space are part of a paragraph.
3127 Successive lines of this form will be word-wrapped when
3128 displayed. The leading space will usually be stripped off.
3132 Those starting with two or more spaces. These will be
3133 displayed verbatim. If the display cannot be panned
3134 horizontally, the displaying program will line wrap them "hard"
3135 (i.e., without taking account of word breaks). If it can they
3136 will be allowed to trail off to the right. None, one or two
3137 initial spaces may be deleted, but the number of spaces
3138 deleted from each line will be the same (so that you can have
3139 indenting work correctly, for example).
3143 Those containing a single space followed by a single full stop
3144 character. These are rendered as blank lines. This is the
3145 <em>only</em> way to get a blank line<footnote>
3146 Completely empty lines will not be rendered as blank lines.
3147 Instead, they will cause the parser to think you're starting
3148 a whole new record in the control file, and will therefore
3149 likely abort with an error.
3154 Those containing a space, a full stop and some more characters.
3155 These are for future expansion. Do not use them.
3161 Do not use tab characters. Their effect is not predictable.
3165 See <ref id="descriptions"> for further information on this.
3169 In a <file>.changes</file> file, the <tt>Description</tt>
3170 field contains a summary of the descriptions for the packages
3171 being uploaded. For this case, the first line of the field
3172 value (the part on the same line as <tt>Description:</tt>) is
3173 always empty. The content of the field is expressed as
3174 continuation lines, one line per package. Each line is
3175 indented by one space and contains the name of a binary
3176 package, a space, a hyphen (<tt>-</tt>), a space, and the
3177 short description line from that package.
3181 <sect1 id="f-Distribution">
3182 <heading><tt>Distribution</tt></heading>
3185 In a <file>.changes</file> file or parsed changelog output
3186 this contains the (space-separated) name(s) of the
3187 distribution(s) where this version of the package should
3188 be installed. Valid distributions are determined by the
3189 archive maintainers.<footnote>
3190 Example distribution names in the Debian archive used in
3191 <file>.changes</file> files are:
3192 <taglist compact="compact">
3193 <tag><em>unstable</em></tag>
3195 This distribution value refers to the
3196 <em>developmental</em> part of the Debian distribution
3197 tree. Most new packages, new upstream versions of
3198 packages and bug fixes go into the <em>unstable</em>
3202 <tag><em>experimental</em></tag>
3204 The packages with this distribution value are deemed
3205 by their maintainers to be high risk. Oftentimes they
3206 represent early beta or developmental packages from
3207 various sources that the maintainers want people to
3208 try, but are not ready to be a part of the other parts
3209 of the Debian distribution tree.
3214 Others are used for updating stable releases or for
3215 security uploads. More information is available in the
3216 Debian Developer's Reference, section "The Debian
3220 The Debian archive software only supports listing a single
3221 distribution. Migration of packages to other distributions is
3222 handled outside of the upload process.
3227 <heading><tt>Date</tt></heading>
3230 This field includes the date the package was built or last
3231 edited. It must be in the same format as the <var>date</var>
3232 in a <file>debian/changelog</file> entry.
3236 The value of this field is usually extracted from the
3237 <file>debian/changelog</file> file - see
3238 <ref id="dpkgchangelog">).
3242 <sect1 id="f-Format">
3243 <heading><tt>Format</tt></heading>
3246 This field specifies a format revision for the file.
3247 The most current format described in the Policy Manual
3248 is version <strong>1.5</strong>. The syntax of the
3249 format value is the same as that of a package version
3250 number except that no epoch or Debian revision is allowed
3251 - see <ref id="f-Version">.
3255 <sect1 id="f-Urgency">
3256 <heading><tt>Urgency</tt></heading>
3259 This is a description of how important it is to upgrade to
3260 this version from previous ones. It consists of a single
3261 keyword taking one of the values <tt>low</tt>,
3262 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3263 <tt>critical</tt><footnote>
3264 Other urgency values are supported with configuration
3265 changes in the archive software but are not used in Debian.
3266 The urgency affects how quickly a package will be considered
3267 for inclusion into the <tt>testing</tt> distribution and
3268 gives an indication of the importance of any fixes included
3269 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3270 treated as synonymous.
3271 </footnote> (not case-sensitive) followed by an optional
3272 commentary (separated by a space) which is usually in
3273 parentheses. For example:
3276 Urgency: low (HIGH for users of diversions)
3282 The value of this field is usually extracted from the
3283 <file>debian/changelog</file> file - see
3284 <ref id="dpkgchangelog">.
3288 <sect1 id="f-Changes">
3289 <heading><tt>Changes</tt></heading>
3292 This field contains the human-readable changes data, describing
3293 the differences between the last version and the current one.
3297 The first line of the field value (the part on the same line
3298 as <tt>Changes:</tt>) is always empty. The content of the
3299 field is expressed as continuation lines, with each line
3300 indented by at least one space. Blank lines must be
3301 represented by a line consisting only of a space and a full
3306 The value of this field is usually extracted from the
3307 <file>debian/changelog</file> file - see
3308 <ref id="dpkgchangelog">).
3312 Each version's change information should be preceded by a
3313 "title" line giving at least the version, distribution(s)
3314 and urgency, in a human-readable way.
3318 If data from several versions is being returned the entry
3319 for the most recent version should be returned first, and
3320 entries should be separated by the representation of a
3321 blank line (the "title" line may also be followed by the
3322 representation of a blank line).
3326 <sect1 id="f-Binary">
3327 <heading><tt>Binary</tt></heading>
3330 This field is a list of binary packages. Its syntax and
3331 meaning varies depending on the control file in which it
3336 When it appears in the <file>.dsc</file> file, it lists binary
3337 packages which a source package can produce, separated by
3339 A space after each comma is conventional.
3340 </footnote>. It may span multiple lines. The source package
3341 does not necessarily produce all of these binary packages for
3342 every architecture. The source control file doesn't contain
3343 details of which architectures are appropriate for which of
3344 the binary packages.
3348 When it appears in a <file>.changes</file> file, it lists the
3349 names of the binary packages being uploaded, separated by
3350 whitespace (not commas). It may span multiple lines.
3354 <sect1 id="f-Installed-Size">
3355 <heading><tt>Installed-Size</tt></heading>
3358 This field appears in the control files of binary packages,
3359 and in the <file>Packages</file> files. It gives an estimate
3360 of the total amount of disk space required to install the
3361 named package. Actual installed size may vary based on block
3362 size, file system properties, or actions taken by package
3367 The disk space is given as the integer value of the estimated
3368 installed size in bytes, divided by 1024 and rounded up.
3372 <sect1 id="f-Files">
3373 <heading><tt>Files</tt></heading>
3376 This field contains a list of files with information about
3377 each one. The exact information and syntax varies with
3382 In all cases, Files is a multiline field. The first line of
3383 the field value (the part on the same line as <tt>Files:</tt>)
3384 is always empty. The content of the field is expressed as
3385 continuation lines, one line per file. Each line must be
3386 indented by one space and contain a number of sub-fields,
3387 separated by spaces, as described below.
3391 In the <file>.dsc</file> file, each line contains the MD5
3392 checksum, size and filename of the tar file and (if
3393 applicable) diff file which make up the remainder of the
3394 source package<footnote>
3395 That is, the parts which are not the <tt>.dsc</tt>.
3396 </footnote>. For example:
3399 c6f698f19f2a2aa07dbb9bbda90a2754 571925 example_1.2.orig.tar.gz
3400 938512f08422f3509ff36f125f5873ba 6220 example_1.2-1.diff.gz
3402 The exact forms of the filenames are described
3403 in <ref id="pkg-sourcearchives">.
3407 In the <file>.changes</file> file this contains one line per
3408 file being uploaded. Each line contains the MD5 checksum,
3409 size, section and priority and the filename. For example:
3412 4c31ab7bfc40d3cf49d7811987390357 1428 text extra example_1.2-1.dsc
3413 c6f698f19f2a2aa07dbb9bbda90a2754 571925 text extra example_1.2.orig.tar.gz
3414 938512f08422f3509ff36f125f5873ba 6220 text extra example_1.2-1.diff.gz
3415 7c98fe853b3bbb47a00e5cd129b6cb56 703542 text extra example_1.2-1_i386.deb
3417 The <qref id="f-Section">section</qref>
3418 and <qref id="f-Priority">priority</qref> are the values of
3419 the corresponding fields in the main source control file. If
3420 no section or priority is specified then <tt>-</tt> should be
3421 used, though section and priority values must be specified for
3422 new packages to be installed properly.
3426 The special value <tt>byhand</tt> for the section in a
3427 <tt>.changes</tt> file indicates that the file in question
3428 is not an ordinary package file and must by installed by
3429 hand by the distribution maintainers. If the section is
3430 <tt>byhand</tt> the priority should be <tt>-</tt>.
3434 If a new Debian revision of a package is being shipped and
3435 no new original source archive is being distributed the
3436 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3437 entry for the original source archive
3438 <file><var>package</var>_<var>upstream-version</var>.orig.tar.gz</file>,
3439 but the <file>.changes</file> file should leave it out. In
3440 this case the original source archive on the distribution
3441 site must match exactly, byte-for-byte, the original
3442 source archive which was used to generate the
3443 <file>.dsc</file> file and diff which are being uploaded.</p>
3446 <sect1 id="f-Closes">
3447 <heading><tt>Closes</tt></heading>
3450 A space-separated list of bug report numbers that the upload
3451 governed by the .changes file closes.
3455 <sect1 id="f-Homepage">
3456 <heading><tt>Homepage</tt></heading>
3459 The URL of the web site for this package, preferably (when
3460 applicable) the site from which the original source can be
3461 obtained and any additional upstream documentation or
3462 information may be found. The content of this field is a
3463 simple URL without any surrounding characters such as
3471 <heading>User-defined fields</heading>
3474 Additional user-defined fields may be added to the
3475 source package control file. Such fields will be
3476 ignored, and not copied to (for example) binary or
3477 source package control files or upload control files.
3481 If you wish to add additional unsupported fields to
3482 these output files you should use the mechanism
3487 Fields in the main source control information file with
3488 names starting <tt>X</tt>, followed by one or more of
3489 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3490 be copied to the output files. Only the part of the
3491 field name after the hyphen will be used in the output
3492 file. Where the letter <tt>B</tt> is used the field
3493 will appear in binary package control files, where the
3494 letter <tt>S</tt> is used in source package control
3495 files and where <tt>C</tt> is used in upload control
3496 (<tt>.changes</tt>) files.
3500 For example, if the main source information control file
3503 XBS-Comment: I stand between the candle and the star.
3505 then the binary and source package control files will contain the
3508 Comment: I stand between the candle and the star.
3517 <chapt id="maintainerscripts">
3518 <heading>Package maintainer scripts and installation procedure</heading>
3521 <heading>Introduction to package maintainer scripts</heading>
3524 It is possible to supply scripts as part of a package which
3525 the package management system will run for you when your
3526 package is installed, upgraded or removed.
3530 These scripts are the files <prgn>preinst</prgn>,
3531 <prgn>postinst</prgn>, <prgn>prerm</prgn> and
3532 <prgn>postrm</prgn> in the control area of the package.
3533 They must be proper executable files; if they are scripts
3534 (which is recommended), they must start with the usual
3535 <tt>#!</tt> convention. They should be readable and
3536 executable by anyone, and must not be world-writable.
3540 The package management system looks at the exit status from
3541 these scripts. It is important that they exit with a
3542 non-zero status if there is an error, so that the package
3543 management system can stop its processing. For shell
3544 scripts this means that you <em>almost always</em> need to
3545 use <tt>set -e</tt> (this is usually true when writing shell
3546 scripts, in fact). It is also important, of course, that
3547 they exit with a zero status if everything went well.
3551 Additionally, packages interacting with users using
3552 <tt>debconf</tt> in the <prgn>postinst</prgn> script should
3553 install a <prgn>config</prgn> script in the control area,
3554 see <ref id="maintscriptprompt"> for details.
3558 When a package is upgraded a combination of the scripts from
3559 the old and new packages is called during the upgrade
3560 procedure. If your scripts are going to be at all
3561 complicated you need to be aware of this, and may need to
3562 check the arguments to your scripts.
3566 Broadly speaking the <prgn>preinst</prgn> is called before
3567 (a particular version of) a package is unpacked, and the
3568 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3569 before (a version of) a package is removed and the
3570 <prgn>postrm</prgn> afterwards.
3574 Programs called from maintainer scripts should not normally
3575 have a path prepended to them. Before installation is
3576 started, the package management system checks to see if the
3577 programs <prgn>ldconfig</prgn>,
3578 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3579 and <prgn>update-rc.d</prgn> can be found via the
3580 <tt>PATH</tt> environment variable. Those programs, and any
3581 other program that one would expect to be in the
3582 <tt>PATH</tt>, should thus be invoked without an absolute
3583 pathname. Maintainer scripts should also not reset the
3584 <tt>PATH</tt>, though they might choose to modify it by
3585 prepending or appending package-specific directories. These
3586 considerations really apply to all shell scripts.</p>
3589 <sect id="idempotency">
3590 <heading>Maintainer scripts idempotency</heading>
3593 It is necessary for the error recovery procedures that the
3594 scripts be idempotent. This means that if it is run
3595 successfully, and then it is called again, it doesn't bomb
3596 out or cause any harm, but just ensures that everything is
3597 the way it ought to be. If the first call failed, or
3598 aborted half way through for some reason, the second call
3599 should merely do the things that were left undone the first
3600 time, if any, and exit with a success status if everything
3602 This is so that if an error occurs, the user interrupts
3603 <prgn>dpkg</prgn> or some other unforeseen circumstance
3604 happens you don't leave the user with a badly-broken
3605 package when <prgn>dpkg</prgn> attempts to repeat the
3611 <sect id="controllingterminal">
3612 <heading>Controlling terminal for maintainer scripts</heading>
3615 Maintainer scripts are not guaranteed to run with a controlling
3616 terminal and may not be able to interact with the user. They
3617 must be able to fall back to noninteractive behavior if no
3618 controlling terminal is available. Maintainer scripts that
3619 prompt via a program conforming to the Debian Configuration
3620 Management Specification (see <ref id="maintscriptprompt">) may
3621 assume that program will handle falling back to noninteractive
3626 For high-priority prompts without a reasonable default answer,
3627 maintainer scripts may abort if there is no controlling
3628 terminal. However, this situation should be avoided if at all
3629 possible, since it prevents automated or unattended installs.
3630 In most cases, users will consider this to be a bug in the
3635 <sect id="exitstatus">
3636 <heading>Exit status</heading>
3639 Each script must return a zero exit status for
3640 success, or a nonzero one for failure, since the package
3641 management system looks for the exit status of these scripts
3642 and determines what action to take next based on that datum.
3646 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3651 <list compact="compact">
3653 <var>new-preinst</var> <tt>install</tt>
3656 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3659 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3662 <var>old-preinst</var> <tt>abort-upgrade</tt>
3663 <var>new-version</var>
3668 <list compact="compact">
3670 <var>postinst</var> <tt>configure</tt>
3671 <var>most-recently-configured-version</var>
3674 <var>old-postinst</var> <tt>abort-upgrade</tt>
3675 <var>new-version</var>
3678 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3679 <tt>in-favour</tt> <var>package</var>
3680 <var>new-version</var>
3683 <var>postinst</var> <tt>abort-remove</tt>
3686 <var>deconfigured's-postinst</var>
3687 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3688 <var>failed-install-package</var> <var>version</var>
3689 [<tt>removing</tt> <var>conflicting-package</var>
3695 <list compact="compact">
3697 <var>prerm</var> <tt>remove</tt>
3700 <var>old-prerm</var> <tt>upgrade</tt>
3701 <var>new-version</var>
3704 <var>new-prerm</var> <tt>failed-upgrade</tt>
3705 <var>old-version</var>
3708 <var>conflictor's-prerm</var> <tt>remove</tt>
3709 <tt>in-favour</tt> <var>package</var>
3710 <var>new-version</var>
3713 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3714 <tt>in-favour</tt> <var>package-being-installed</var>
3715 <var>version</var> [<tt>removing</tt>
3716 <var>conflicting-package</var>
3722 <list compact="compact">
3724 <var>postrm</var> <tt>remove</tt>
3727 <var>postrm</var> <tt>purge</tt>
3730 <var>old-postrm</var> <tt>upgrade</tt>
3731 <var>new-version</var>
3734 <var>new-postrm</var> <tt>failed-upgrade</tt>
3735 <var>old-version</var>
3738 <var>new-postrm</var> <tt>abort-install</tt>
3741 <var>new-postrm</var> <tt>abort-install</tt>
3742 <var>old-version</var>
3745 <var>new-postrm</var> <tt>abort-upgrade</tt>
3746 <var>old-version</var>
3749 <var>disappearer's-postrm</var> <tt>disappear</tt>
3750 <var>overwriter</var>
3751 <var>overwriter-version</var>
3757 <sect id="unpackphase">
3758 <heading>Details of unpack phase of installation or upgrade</heading>
3761 The procedure on installation/upgrade/overwrite/disappear
3762 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3763 stage of <tt>dpkg --install</tt>) is as follows. In each
3764 case, if a major error occurs (unless listed below) the
3765 actions are, in general, run backwards - this means that the
3766 maintainer scripts are run with different arguments in
3767 reverse order. These are the "error unwind" calls listed
3774 If a version of the package is already installed, call
3775 <example compact="compact">
3776 <var>old-prerm</var> upgrade <var>new-version</var>
3780 If the script runs but exits with a non-zero
3781 exit status, <prgn>dpkg</prgn> will attempt:
3782 <example compact="compact">
3783 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3785 If this works, the upgrade continues. If this
3786 does not work, the error unwind:
3787 <example compact="compact">
3788 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3790 If this works, then the old-version is
3791 "Installed", if not, the old version is in a
3792 "Half-Configured" state.
3798 If a "conflicting" package is being removed at the same time,
3799 or if any package will be broken (due to <tt>Breaks</tt>):
3802 If <tt>--auto-deconfigure</tt> is
3803 specified, call, for each package to be deconfigured
3804 due to <tt>Breaks</tt>:
3805 <example compact="compact">
3806 <var>deconfigured's-prerm</var> deconfigure \
3807 in-favour <var>package-being-installed</var> <var>version</var>
3810 <example compact="compact">
3811 <var>deconfigured's-postinst</var> abort-deconfigure \
3812 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3814 The deconfigured packages are marked as
3815 requiring configuration, so that if
3816 <tt>--install</tt> is used they will be
3817 configured again if possible.
3820 If any packages depended on a conflicting
3821 package being removed and <tt>--auto-deconfigure</tt> is
3822 specified, call, for each such package:
3823 <example compact="compact">
3824 <var>deconfigured's-prerm</var> deconfigure \
3825 in-favour <var>package-being-installed</var> <var>version</var> \
3826 removing <var>conflicting-package</var> <var>version</var>
3829 <example compact="compact">
3830 <var>deconfigured's-postinst</var> abort-deconfigure \
3831 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3832 removing <var>conflicting-package</var> <var>version</var>
3834 The deconfigured packages are marked as
3835 requiring configuration, so that if
3836 <tt>--install</tt> is used they will be
3837 configured again if possible.
3840 To prepare for removal of each conflicting package, call:
3841 <example compact="compact">
3842 <var>conflictor's-prerm</var> remove \
3843 in-favour <var>package</var> <var>new-version</var>
3846 <example compact="compact">
3847 <var>conflictor's-postinst</var> abort-remove \
3848 in-favour <var>package</var> <var>new-version</var>
3857 If the package is being upgraded, call:
3858 <example compact="compact">
3859 <var>new-preinst</var> upgrade <var>old-version</var>
3861 If this fails, we call:
3863 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3870 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3872 is called. If this works, then the old version
3873 is in an "Installed" state, or else it is left
3874 in an "Unpacked" state.
3879 If it fails, then the old version is left
3880 in an "Half-Installed" state.
3887 Otherwise, if the package had some configuration
3888 files from a previous version installed (i.e., it
3889 is in the "configuration files only" state):
3890 <example compact="compact">
3891 <var>new-preinst</var> install <var>old-version</var>
3895 <var>new-postrm</var> abort-install <var>old-version</var>
3897 If this fails, the package is left in a
3898 "Half-Installed" state, which requires a
3899 reinstall. If it works, the packages is left in
3900 a "Config-Files" state.
3903 Otherwise (i.e., the package was completely purged):
3904 <example compact="compact">
3905 <var>new-preinst</var> install
3908 <example compact="compact">
3909 <var>new-postrm</var> abort-install
3911 If the error-unwind fails, the package is in a
3912 "Half-Installed" phase, and requires a
3913 reinstall. If the error unwind works, the
3914 package is in a not installed state.
3921 The new package's files are unpacked, overwriting any
3922 that may be on the system already, for example any
3923 from the old version of the same package or from
3924 another package. Backups of the old files are kept
3925 temporarily, and if anything goes wrong the package
3926 management system will attempt to put them back as
3927 part of the error unwind.
3931 It is an error for a package to contain files which
3932 are on the system in another package, unless
3933 <tt>Replaces</tt> is used (see <ref id="replaces">).
3935 The following paragraph is not currently the case:
3936 Currently the <tt>- - force-overwrite</tt> flag is
3937 enabled, downgrading it to a warning, but this may not
3943 It is a more serious error for a package to contain a
3944 plain file or other kind of non-directory where another
3945 package has a directory (again, unless
3946 <tt>Replaces</tt> is used). This error can be
3947 overridden if desired using
3948 <tt>--force-overwrite-dir</tt>, but this is not
3953 Packages which overwrite each other's files produce
3954 behavior which, though deterministic, is hard for the
3955 system administrator to understand. It can easily
3956 lead to "missing" programs if, for example, a package
3957 is unpacked which overwrites a file from another
3958 package, and is then removed again.<footnote>
3959 Part of the problem is due to what is arguably a
3960 bug in <prgn>dpkg</prgn>.
3965 A directory will never be replaced by a symbolic link
3966 to a directory or vice versa; instead, the existing
3967 state (symlink or not) will be left alone and
3968 <prgn>dpkg</prgn> will follow the symlink if there is
3977 If the package is being upgraded, call
3978 <example compact="compact">
3979 <var>old-postrm</var> upgrade <var>new-version</var>
3983 If this fails, <prgn>dpkg</prgn> will attempt:
3984 <example compact="compact">
3985 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3987 If this works, installation continues. If not,
3989 <example compact="compact">
3990 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3992 If this fails, the old version is left in a
3993 "Half-Installed" state. If it works, dpkg now
3995 <example compact="compact">
3996 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3998 If this fails, the old version is left in a
3999 "Half-Installed" state. If it works, dpkg now
4001 <example compact="compact">
4002 <var>old-postinst</var> abort-upgrade <var>new-version</var>
4004 If this fails, the old version is in an
4011 This is the point of no return - if
4012 <prgn>dpkg</prgn> gets this far, it won't back off
4013 past this point if an error occurs. This will
4014 leave the package in a fairly bad state, which
4015 will require a successful re-installation to clear
4016 up, but it's when <prgn>dpkg</prgn> starts doing
4017 things that are irreversible.
4022 Any files which were in the old version of the package
4023 but not in the new are removed.
4027 The new file list replaces the old.
4031 The new maintainer scripts replace the old.
4035 Any packages all of whose files have been overwritten
4036 during the installation, and which aren't required for
4037 dependencies, are considered to have been removed.
4038 For each such package
4041 <prgn>dpkg</prgn> calls:
4042 <example compact="compact">
4043 <var>disappearer's-postrm</var> disappear \
4044 <var>overwriter</var> <var>overwriter-version</var>
4048 The package's maintainer scripts are removed.
4051 It is noted in the status database as being in a
4052 sane state, namely not installed (any conffiles
4053 it may have are ignored, rather than being
4054 removed by <prgn>dpkg</prgn>). Note that
4055 disappearing packages do not have their prerm
4056 called, because <prgn>dpkg</prgn> doesn't know
4057 in advance that the package is going to
4064 Any files in the package we're unpacking that are also
4065 listed in the file lists of other packages are removed
4066 from those lists. (This will lobotomize the file list
4067 of the "conflicting" package if there is one.)
4071 The backup files made during installation, above, are
4077 The new package's status is now sane, and recorded as
4082 Here is another point of no return - if the
4083 conflicting package's removal fails we do not unwind
4084 the rest of the installation; the conflicting package
4085 is left in a half-removed limbo.
4090 If there was a conflicting package we go and do the
4091 removal actions (described below), starting with the
4092 removal of the conflicting package's files (any that
4093 are also in the package being unpacked have already
4094 been removed from the conflicting package's file list,
4095 and so do not get removed now).
4101 <sect id="configdetails"><heading>Details of configuration</heading>
4104 When we configure a package (this happens with <tt>dpkg
4105 --install</tt> and <tt>dpkg --configure</tt>), we first
4106 update any <tt>conffile</tt>s and then call:
4107 <example compact="compact">
4108 <var>postinst</var> configure <var>most-recently-configured-version</var>
4113 No attempt is made to unwind after errors during
4114 configuration. If the configuration fails, the package is in
4115 a "Failed Config" state, and an error message is generated.
4119 If there is no most recently configured version
4120 <prgn>dpkg</prgn> will pass a null argument.
4123 Historical note: Truly ancient (pre-1997) versions of
4124 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4125 (including the angle brackets) in this case. Even older
4126 ones did not pass a second argument at all, under any
4127 circumstance. Note that upgrades using such an old dpkg
4128 version are unlikely to work for other reasons, even if
4129 this old argument behavior is handled by your postinst script.
4135 <sect id="removedetails"><heading>Details of removal and/or
4136 configuration purging</heading>
4142 <example compact="compact">
4143 <var>prerm</var> remove
4147 If prerm fails during replacement due to conflict
4149 <var>conflictor's-postinst</var> abort-remove \
4150 in-favour <var>package</var> <var>new-version</var>
4154 <var>postinst</var> abort-remove
4158 If this fails, the package is in a "Half-Configured"
4159 state, or else it remains "Installed".
4163 The package's files are removed (except <tt>conffile</tt>s).
4166 <example compact="compact">
4167 <var>postrm</var> remove
4171 If it fails, there's no error unwind, and the package is in
4172 an "Half-Installed" state.
4177 All the maintainer scripts except the <prgn>postrm</prgn>
4182 If we aren't purging the package we stop here. Note
4183 that packages which have no <prgn>postrm</prgn> and no
4184 <tt>conffile</tt>s are automatically purged when
4185 removed, as there is no difference except for the
4186 <prgn>dpkg</prgn> status.
4190 The <tt>conffile</tt>s and any backup files
4191 (<tt>~</tt>-files, <tt>#*#</tt> files,
4192 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4197 <example compact="compact">
4198 <var>postrm</var> purge
4202 If this fails, the package remains in a "Config-Files"
4207 The package's file list is removed.
4216 <chapt id="relationships">
4217 <heading>Declaring relationships between packages</heading>
4219 <sect id="depsyntax">
4220 <heading>Syntax of relationship fields</heading>
4223 These fields all have a uniform syntax. They are a list of
4224 package names separated by commas.
4228 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4229 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4230 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4231 control file fields of the package, which declare
4232 dependencies on other packages, the package names listed may
4233 also include lists of alternative package names, separated
4234 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4235 if any one of the alternative packages is installed, that
4236 part of the dependency is considered to be satisfied.
4240 All of the fields except for <tt>Provides</tt> may restrict
4241 their applicability to particular versions of each named
4242 package. This is done in parentheses after each individual
4243 package name; the parentheses should contain a relation from
4244 the list below followed by a version number, in the format
4245 described in <ref id="f-Version">.
4249 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4250 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4251 strictly earlier, earlier or equal, exactly equal, later or
4252 equal and strictly later, respectively. The deprecated
4253 forms <tt><</tt> and <tt>></tt> were used to mean
4254 earlier/later or equal, rather than strictly earlier/later,
4255 so they should not appear in new packages (though
4256 <prgn>dpkg</prgn> still supports them).
4260 Whitespace may appear at any point in the version
4261 specification subject to the rules in <ref
4262 id="controlsyntax">, and must appear where it's necessary to
4263 disambiguate; it is not otherwise significant. All of the
4264 relationship fields may span multiple lines. For
4265 consistency and in case of future changes to
4266 <prgn>dpkg</prgn> it is recommended that a single space be
4267 used after a version relationship and before a version
4268 number; it is also conventional to put a single space after
4269 each comma, on either side of each vertical bar, and before
4270 each open parenthesis. When wrapping a relationship field, it
4271 is conventional to do so after a comma and before the space
4272 following that comma.
4276 For example, a list of dependencies might appear as:
4277 <example compact="compact">
4280 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4285 All fields that specify build-time relationships
4286 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4287 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
4288 may be restricted to a certain set of architectures. This
4289 is indicated in brackets after each individual package name and
4290 the optional version specification. The brackets enclose a
4291 list of Debian architecture names separated by whitespace.
4292 Exclamation marks may be prepended to each of the names.
4293 (It is not permitted for some names to be prepended with
4294 exclamation marks while others aren't.) If the current Debian
4295 host architecture is not in this list and there are no
4296 exclamation marks in the list, or it is in the list with a
4297 prepended exclamation mark, the package name and the
4298 associated version specification are ignored completely for
4299 the purposes of defining the relationships.
4304 <example compact="compact">
4306 Build-Depends-Indep: texinfo
4307 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4308 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4310 requires <tt>kernel-headers-2.2.10</tt> on all architectures
4311 other than hurd-i386 and requires <tt>hurd-dev</tt> and
4312 <tt>gnumach-dev</tt> only on hurd-i386.
4316 If the architecture-restricted dependency is part of a set of
4317 alternatives using <tt>|</tt>, that alternative is ignored
4318 completely on architectures that do not match the restriction.
4320 <example compact="compact">
4321 Build-Depends: foo [!i386] | bar [!amd64]
4323 is equivalent to <tt>bar</tt> on the i386 architecture, to
4324 <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
4325 bar</tt> on all other architectures.
4329 All fields that specify build-time relationships may also be
4330 restricted to a certain set of architectures using architecture
4331 wildcards. The syntax for declaring such restrictions is the
4332 same as declaring restrictions using a certain set of
4333 architectures without architecture wildcards. For example:
4334 <example compact="compact">
4335 Build-Depends: foo [linux-any], bar [any-i386], baz [!linux-any]
4337 is equivalent to <tt>foo</tt> on architectures using the Linux
4338 kernel and any cpu, <tt>bar</tt> on architectures using any
4339 kernel and an i386 cpu, and <tt>baz</tt> on any architecture
4340 using a kernel other than Linux.
4344 Note that the binary package relationship fields such as
4345 <tt>Depends</tt> appear in one of the binary package
4346 sections of the control file, whereas the build-time
4347 relationships such as <tt>Build-Depends</tt> appear in the
4348 source package section of the control file (which is the
4353 <sect id="binarydeps">
4354 <heading>Binary Dependencies - <tt>Depends</tt>,
4355 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4356 <tt>Pre-Depends</tt>
4360 Packages can declare in their control file that they have
4361 certain relationships to other packages - for example, that
4362 they may not be installed at the same time as certain other
4363 packages, and/or that they depend on the presence of others.
4367 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4368 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4369 <tt>Breaks</tt> and <tt>Conflicts</tt> control file fields.
4370 <tt>Breaks</tt> is described in <ref id="breaks">, and
4371 <tt>Conflicts</tt> is described in <ref id="conflicts">. The
4372 rest are described below.
4376 These seven fields are used to declare a dependency
4377 relationship by one package on another. Except for
4378 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4379 depending (binary) package's control file.
4380 (<tt>Enhances</tt> appears in the recommending package's
4381 control file, and <tt>Breaks</tt> appears in the version of
4382 depended-on package which causes the named package to
4387 A <tt>Depends</tt> field takes effect <em>only</em> when a
4388 package is to be configured. It does not prevent a package
4389 being on the system in an unconfigured state while its
4390 dependencies are unsatisfied, and it is possible to replace
4391 a package whose dependencies are satisfied and which is
4392 properly installed with a different version whose
4393 dependencies are not and cannot be satisfied; when this is
4394 done the depending package will be left unconfigured (since
4395 attempts to configure it will give errors) and will not
4396 function properly. If it is necessary, a
4397 <tt>Pre-Depends</tt> field can be used, which has a partial
4398 effect even when a package is being unpacked, as explained
4399 in detail below. (The other three dependency fields,
4400 <tt>Recommends</tt>, <tt>Suggests</tt> and
4401 <tt>Enhances</tt>, are only used by the various front-ends
4402 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4403 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4407 Since <tt>Depends</tt> only places requirements on the
4408 configuration step, packages in an installation run are usually
4409 all unpacked first and all configured later. This makes it
4410 easier to satisfy all dependencies when multiple packages are
4415 If there is a circular dependency among packages being installed
4416 or removed, installation or removal order honoring the
4417 dependency order is impossible, requiring the dependency loop be
4418 broken at some point and the dependency requirements violated
4419 for at least one package. Packages involved in circular
4420 dependencies may not be able to rely on their dependencies being
4421 configured when being configured or removed depending on which
4422 side of the break of the circular dependency loop they happen to
4423 be on. If one of the packages in the loop has no
4424 <prgn>postinst</prgn> script, then the cycle will be broken at
4425 that package; this ensures that all <prgn>postinst</prgn>
4426 scripts are run with their dependencies properly configured if
4427 this is possible. Otherwise the breaking point is arbitrary.
4428 Packages should therefore avoid circular dependencies where
4429 possible, particularly if they have <prgn>postinst</prgn>
4434 The meaning of the five dependency fields is as follows:
4436 <tag><tt>Depends</tt></tag>
4439 This declares an absolute dependency. A package will
4440 not be configured unless all of the packages listed in
4441 its <tt>Depends</tt> field have been correctly
4442 configured (unless there is a circular dependency as
4447 The <tt>Depends</tt> field should be used if the
4448 depended-on package is required for the depending
4449 package to provide a significant amount of
4454 The <tt>Depends</tt> field should also be used if the
4455 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4456 <prgn>postrm</prgn> scripts require the package to be
4457 present in order to run. (If both packages are involved
4458 in a dependency loop, this might not work as expected; see
4459 the explanation a few paragraphs back.) In the case of
4460 <prgn>postinst</prgn> and <prgn>postrm</prgn>, the
4461 depended-on packages will be unpacked and configured
4462 first. (Note, however, that the <prgn>postrm</prgn>
4463 cannot rely on any non-essential packages to be present
4464 during the <tt>purge</tt> phase.) In the case of
4465 <prgn>prerm</prgn>, the depended-on package will at least
4466 be unpacked (it might be configured too, but you can't
4467 rely on this unless you use <tt>Pre-Depends</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. However, unlike
4531 with <tt>Depends</tt>, <tt>Pre-Depends</tt> does not
4532 permit circular dependencies to be broken. If a circular
4533 dependency is encountered while attempting to honor
4534 <tt>Pre-Depends</tt>, the installation will be aborted.
4538 <tt>Pre-Depends</tt> are also required if the
4539 <prgn>preinst</prgn> script depends on the named package.
4540 It is best to avoid this situation if possible.
4544 <tt>Pre-Depends</tt> should be used sparingly,
4545 preferably only by packages whose premature upgrade or
4546 installation would hamper the ability of the system to
4547 continue with any upgrade that might be in progress.
4554 When selecting which level of dependency to use you should
4555 consider how important the depended-on package is to the
4556 functionality of the one declaring the dependency. Some
4557 packages are composed of components of varying degrees of
4558 importance. Such a package should list using
4559 <tt>Depends</tt> the package(s) which are required by the
4560 more important components. The other components'
4561 requirements may be mentioned as Suggestions or
4562 Recommendations, as appropriate to the components' relative
4568 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4571 When one binary package declares that it breaks another,
4572 <prgn>dpkg</prgn> will refuse to allow the package which
4573 declares <tt>Breaks</tt> be unpacked unless the broken
4574 package is deconfigured first, and it will refuse to
4575 allow the broken package to be reconfigured.
4579 A package will not be regarded as causing breakage merely
4580 because its configuration files are still installed; it must
4581 be at least "Half-Installed".
4585 A special exception is made for packages which declare that
4586 they break their own package name or a virtual package which
4587 they provide (see below): this does not count as a real
4592 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4593 version clause; such a <tt>Breaks</tt> is introduced in the
4594 version of an (implicit or explicit) dependency which
4595 violates an assumption or reveals a bug in earlier versions
4596 of the broken package. This use of <tt>Breaks</tt> will
4597 inform higher-level package management tools that broken
4598 package must be upgraded before the new one.
4602 If the breaking package also overwrites some files from the
4603 older package, it should use <tt>Replaces</tt> (not
4604 <tt>Conflicts</tt>) to ensure this goes smoothly.
4608 <sect id="conflicts">
4609 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4612 When one binary package declares a conflict with another
4613 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4614 refuse to allow them to be unpacked on the system at the
4619 If one package is to be unpacked, the other must be removed
4620 first - if the package being unpacked is marked as
4621 replacing (see <ref id="replaces">) the one on the system,
4622 or the one on the system is marked as deselected, or both
4623 packages are marked <tt>Essential</tt>, then
4624 <prgn>dpkg</prgn> will automatically remove the package
4625 which is causing the conflict, otherwise it will halt the
4626 installation of the new package with an error. This
4627 mechanism is specifically designed to produce an error when
4628 the installed package is <tt>Essential</tt>, but the new
4633 A package will not cause a conflict merely because its
4634 configuration files are still installed; it must be at least
4639 A special exception is made for packages which declare a
4640 conflict with their own package name, or with a virtual
4641 package which they provide (see below): this does not
4642 prevent their installation, and allows a package to conflict
4643 with others providing a replacement for it. You use this
4644 feature when you want the package in question to be the only
4645 package providing some feature.
4649 A <tt>Conflicts</tt> entry should almost never have an
4650 "earlier than" version clause. This would prevent
4651 <prgn>dpkg</prgn> from upgrading or installing the package
4652 which declared such a conflict until the upgrade or removal
4653 of the conflicted-with package had been completed. Instead,
4654 <tt>Breaks</tt> may be used.
4658 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4662 As well as the names of actual ("concrete") packages, the
4663 package relationship fields <tt>Depends</tt>,
4664 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4665 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4666 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4667 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4668 may mention "virtual packages".
4672 A <em>virtual package</em> is one which appears in the
4673 <tt>Provides</tt> control file field of another package.
4674 The effect is as if the package(s) which provide a
4675 particular virtual package name had been listed by name
4676 everywhere the virtual package name appears. (See also <ref
4681 If there are both concrete and virtual packages of the same
4682 name, then the dependency may be satisfied (or the conflict
4683 caused) by either the concrete package with the name in
4684 question or any other concrete package which provides the
4685 virtual package with the name in question. This is so that,
4686 for example, supposing we have
4687 <example compact="compact">
4690 </example> and someone else releases an enhanced version of
4691 the <tt>bar</tt> package they can say:
4692 <example compact="compact">
4696 and the <tt>bar-plus</tt> package will now also satisfy the
4697 dependency for the <tt>foo</tt> package.
4701 If a relationship field has a version number attached
4702 then only real packages will be considered to see whether
4703 the relationship is satisfied (or the prohibition violated,
4704 for a conflict or breakage) - it is assumed that a real
4705 package which provides the virtual package is not of the
4706 "right" version. So, a <tt>Provides</tt> field may not
4707 contain version numbers, and the version number of the
4708 concrete package which provides a particular virtual package
4709 will not be looked at when considering a dependency on or
4710 conflict with the virtual package name.
4714 It is likely that the ability will be added in a future
4715 release of <prgn>dpkg</prgn> to specify a version number for
4716 each virtual package it provides. This feature is not yet
4717 present, however, and is expected to be used only
4722 If you want to specify which of a set of real packages
4723 should be the default to satisfy a particular dependency on
4724 a virtual package, you should list the real package as an
4725 alternative before the virtual one.
4730 <sect id="replaces"><heading>Overwriting files and replacing
4731 packages - <tt>Replaces</tt></heading>
4734 Packages can declare in their control file that they should
4735 overwrite files in certain other packages, or completely
4736 replace other packages. The <tt>Replaces</tt> control file
4737 field has these two distinct purposes.
4740 <sect1><heading>Overwriting files in other packages</heading>
4743 Firstly, as mentioned before, it is usually an error for a
4744 package to contain files which are on the system in
4749 However, if the overwriting package declares that it
4750 <tt>Replaces</tt> the one containing the file being
4751 overwritten, then <prgn>dpkg</prgn> will replace the file
4752 from the old package with that from the new. The file
4753 will no longer be listed as "owned" by the old package.
4757 If a package is completely replaced in this way, so that
4758 <prgn>dpkg</prgn> does not know of any files it still
4759 contains, it is considered to have "disappeared". It will
4760 be marked as not wanted on the system (selected for
4761 removal) and not installed. Any <tt>conffile</tt>s
4762 details noted for the package will be ignored, as they
4763 will have been taken over by the overwriting package. The
4764 package's <prgn>postrm</prgn> script will be run with a
4765 special argument to allow the package to do any final
4766 cleanup required. See <ref id="mscriptsinstact">.
4769 Replaces is a one way relationship -- you have to
4770 install the replacing package after the replaced
4777 For this usage of <tt>Replaces</tt>, virtual packages (see
4778 <ref id="virtual">) are not considered when looking at a
4779 <tt>Replaces</tt> field - the packages declared as being
4780 replaced must be mentioned by their real names.
4784 Furthermore, this usage of <tt>Replaces</tt> only takes
4785 effect when both packages are at least partially on the
4786 system at once, so that it can only happen if they do not
4787 conflict or if the conflict has been overridden.
4792 <sect1><heading>Replacing whole packages, forcing their
4796 Secondly, <tt>Replaces</tt> allows the packaging system to
4797 resolve which package should be removed when there is a
4798 conflict - see <ref id="conflicts">. This usage only
4799 takes effect when the two packages <em>do</em> conflict,
4800 so that the two usages of this field do not interfere with
4805 In this situation, the package declared as being replaced
4806 can be a virtual package, so for example, all mail
4807 transport agents (MTAs) would have the following fields in
4808 their control files:
4809 <example compact="compact">
4810 Provides: mail-transport-agent
4811 Conflicts: mail-transport-agent
4812 Replaces: mail-transport-agent
4814 ensuring that only one MTA can be unpacked at any one
4819 <sect id="sourcebinarydeps">
4820 <heading>Relationships between source and binary packages -
4821 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4822 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4826 Source packages that require certain binary packages to be
4827 installed or absent at the time of building the package
4828 can declare relationships to those binary packages.
4832 This is done using the <tt>Build-Depends</tt>,
4833 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4834 <tt>Build-Conflicts-Indep</tt> control file fields.
4838 Build-dependencies on "build-essential" binary packages can be
4839 omitted. Please see <ref id="pkg-relations"> for more information.
4843 The dependencies and conflicts they define must be satisfied
4844 (as defined earlier for binary packages) in order to invoke
4845 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4847 If you make "build-arch" or "binary-arch", you need
4848 Build-Depends. If you make "build-indep" or
4849 "binary-indep", you need Build-Depends and
4850 Build-Depends-Indep. If you make "build" or "binary",
4854 There is no Build-Depends-Arch; this role is essentially
4855 met with Build-Depends. Anyone building the
4856 <tt>build-indep</tt> and binary-indep<tt></tt> targets
4857 is basically assumed to be building the whole package
4858 anyway and so installs all build dependencies. The
4859 autobuilders use <tt>dpkg-buildpackage -B</tt>, which
4860 calls <tt>build</tt> (not <tt>build-arch</tt>, since it
4861 does not yet know how to check for its existence) and
4862 <tt>binary-arch</tt>.
4865 The purpose of the original split, I recall, was so that
4866 the autobuilders wouldn't need to install extra packages
4867 needed only for the binary-indep targets. But without a
4868 build-arch/build-indep split, this didn't work, since
4869 most of the work is done in the build target, not in the
4875 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4877 The <tt>Build-Depends</tt> and
4878 <tt>Build-Conflicts</tt> fields must be satisfied when
4879 any of the following targets is invoked:
4880 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4881 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4882 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4884 <tag><tt>Build-Depends-Indep</tt>,
4885 <tt>Build-Conflicts-Indep</tt></tag>
4887 The <tt>Build-Depends-Indep</tt> and
4888 <tt>Build-Conflicts-Indep</tt> fields must be
4889 satisfied when any of the following targets is
4890 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4891 <tt>binary</tt> and <tt>binary-indep</tt>.
4901 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4904 Packages containing shared libraries must be constructed with
4905 a little care to make sure that the shared library is always
4906 available. This is especially important for packages whose
4907 shared libraries are vitally important, such as the C library
4908 (currently <tt>libc6</tt>).
4912 Packages involving shared libraries should be split up into
4913 several binary packages. This section mostly deals with how
4914 this separation is to be accomplished; rules for files within
4915 the shared library packages are in <ref id="libraries"> instead.
4918 <sect id="sharedlibs-runtime">
4919 <heading>Run-time shared libraries</heading>
4922 The run-time shared library needs to be placed in a package
4923 whose name changes whenever the shared object version
4926 Since it is common place to install several versions of a
4927 package that just provides shared libraries, it is a
4928 good idea that the library package should not
4929 contain any extraneous non-versioned files, unless they
4930 happen to be in versioned directories.</p>
4932 The most common mechanism is to place it in a package
4934 <package><var>libraryname</var><var>soversion</var></package>,
4935 where <file><var>soversion</var></file> is the version number
4936 in the soname of the shared library<footnote>
4937 The soname is the shared object name: it's the thing
4938 that has to match exactly between building an executable
4939 and running it for the dynamic linker to be able run the
4940 program. For example, if the soname of the library is
4941 <file>libfoo.so.6</file>, the library package would be
4942 called <file>libfoo6</file>.
4944 Alternatively, if it would be confusing to directly append
4945 <var>soversion</var> to <var>libraryname</var> (e.g. because
4946 <var>libraryname</var> itself ends in a number), you may use
4947 <package><var>libraryname</var>-<var>soversion</var></package> and
4948 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4953 If you have several shared libraries built from the same
4954 source tree you may lump them all together into a single
4955 shared library package, provided that you change all of
4956 their sonames at once (so that you don't get filename
4957 clashes if you try to install different versions of the
4958 combined shared libraries package).
4962 The package should install the shared libraries under
4963 their normal names. For example, the <package>libgdbm3</package>
4964 package should install <file>libgdbm.so.3.0.0</file> as
4965 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4966 renamed or re-linked by any <prgn>prerm</prgn> or
4967 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4968 of renaming things safely without affecting running programs,
4969 and attempts to interfere with this are likely to lead to
4974 Shared libraries should not be installed executable, since
4975 the dynamic linker does not require this and trying to
4976 execute a shared library usually results in a core dump.
4980 The run-time library package should include the symbolic link that
4981 <prgn>ldconfig</prgn> would create for the shared libraries.
4982 For example, the <package>libgdbm3</package> package should include
4983 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4984 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4985 linker (for example <prgn>ld.so</prgn> or
4986 <prgn>ld-linux.so.*</prgn>) can find the library between the
4987 time that <prgn>dpkg</prgn> installs it and the time that
4988 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4990 The package management system requires the library to be
4991 placed before the symbolic link pointing to it in the
4992 <file>.deb</file> file. This is so that when
4993 <prgn>dpkg</prgn> comes to install the symlink
4994 (overwriting the previous symlink pointing at an older
4995 version of the library), the new shared library is already
4996 in place. In the past, this was achieved by creating the
4997 library in the temporary packaging directory before
4998 creating the symlink. Unfortunately, this was not always
4999 effective, since the building of the tar file in the
5000 <file>.deb</file> depended on the behavior of the underlying
5001 file system. Some file systems (such as reiserfs) reorder
5002 the files so that the order of creation is forgotten.
5003 Since version 1.7.0, <prgn>dpkg</prgn>
5004 reorders the files itself as necessary when building a
5005 package. Thus it is no longer important to concern
5006 oneself with the order of file creation.
5010 <sect1 id="ldconfig">
5011 <heading><tt>ldconfig</tt></heading>
5014 Any package installing shared libraries in one of the default
5015 library directories of the dynamic linker (which are currently
5016 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
5017 listed in <file>/etc/ld.so.conf</file><footnote>
5019 <list compact="compact">
5020 <item>/usr/local/lib</item>
5021 <item>/usr/lib/libc5-compat</item>
5022 <item>/lib/libc5-compat</item>
5025 must use <prgn>ldconfig</prgn> to update the shared library
5030 The package maintainer scripts must only call
5031 <prgn>ldconfig</prgn> under these circumstances:
5032 <list compact="compact">
5033 <item>When the <prgn>postinst</prgn> script is run with a
5034 first argument of <tt>configure</tt>, the script must call
5035 <prgn>ldconfig</prgn>, and may optionally invoke
5036 <prgn>ldconfig</prgn> at other times.
5038 <item>When the <prgn>postrm</prgn> script is run with a
5039 first argument of <tt>remove</tt>, the script should call
5040 <prgn>ldconfig</prgn>.
5045 During install or upgrade, the preinst is called before
5046 the new files are unpacked, so calling "ldconfig" is
5047 pointless. The preinst of an existing package can also be
5048 called if an upgrade fails. However, this happens during
5049 the critical time when a shared libs may exist on-disk
5050 under a temporary name. Thus, it is dangerous and
5051 forbidden by current policy to call "ldconfig" at this
5056 When a package is installed or upgraded, "postinst
5057 configure" runs after the new files are safely on-disk.
5058 Since it is perfectly safe to invoke ldconfig
5059 unconditionally in a postinst, it is OK for a package to
5060 simply put ldconfig in its postinst without checking the
5061 argument. The postinst can also be called to recover from
5062 a failed upgrade. This happens before any new files are
5063 unpacked, so there is no reason to call "ldconfig" at this
5068 For a package that is being removed, prerm is
5069 called with all the files intact, so calling ldconfig is
5070 useless. The other calls to "prerm" happen in the case of
5071 upgrade at a time when all the files of the old package
5072 are on-disk, so again calling "ldconfig" is pointless.
5076 postrm, on the other hand, is called with the "remove"
5077 argument just after the files are removed, so this is
5078 the proper time to call "ldconfig" to notify the system
5079 of the fact that the shared libraries from the package
5080 are removed. The postrm can be called at several other
5081 times. At the time of "postrm purge", "postrm
5082 abort-install", or "postrm abort-upgrade", calling
5083 "ldconfig" is useless because the shared lib files are
5084 not on-disk. However, when "postrm" is invoked with
5085 arguments "upgrade", "failed-upgrade", or "disappear", a
5086 shared lib may exist on-disk under a temporary filename.
5094 <sect id="sharedlibs-support-files">
5095 <heading>Shared library support files</heading>
5098 If your package contains files whose names do not change with
5099 each change in the library shared object version, you must not
5100 put them in the shared library package. Otherwise, several
5101 versions of the shared library cannot be installed at the same
5102 time without filename clashes, making upgrades and transitions
5103 unnecessarily difficult.
5107 It is recommended that supporting files and run-time support
5108 programs that do not need to be invoked manually by users, but
5109 are nevertheless required for the package to function, be placed
5110 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
5111 preferably under <file>/usr/lib/</file><var>package-name</var>.
5112 If the program or file is architecture independent, the
5113 recommendation is for it to be placed in a subdirectory of
5114 <file>/usr/share</file> instead, preferably under
5115 <file>/usr/share/</file><var>package-name</var>. Following the
5116 <var>package-name</var> naming convention ensures that the file
5117 names change when the shared object version changes.
5121 Run-time support programs that use the shared library but are
5122 not required for the library to function or files used by the
5123 shared library that can be used by any version of the shared
5124 library package should instead be put in a separate package.
5125 This package might typically be named
5126 <package><var>libraryname</var>-tools</package>; note the
5127 absence of the <var>soversion</var> in the package name.
5131 Files and support programs only useful when compiling software
5132 against the library should be included in the development
5133 package for the library.<footnote>
5134 For example, a <file><var>package-name</var>-config</file>
5135 script or <package>pkg-config</package> configuration files.
5140 <sect id="sharedlibs-static">
5141 <heading>Static libraries</heading>
5144 The static library (<file><var>libraryname.a</var></file>)
5145 is usually provided in addition to the shared version.
5146 It is placed into the development package (see below).
5150 In some cases, it is acceptable for a library to be
5151 available in static form only; these cases include:
5153 <item>libraries for languages whose shared library support
5154 is immature or unstable</item>
5155 <item>libraries whose interfaces are in flux or under
5156 development (commonly the case when the library's
5157 major version number is zero, or where the ABI breaks
5158 across patchlevels)</item>
5159 <item>libraries which are explicitly intended to be
5160 available only in static form by their upstream
5165 <sect id="sharedlibs-dev">
5166 <heading>Development files</heading>
5169 The development files associated to a shared library need to be
5170 placed in a package called
5171 <package><var>libraryname</var><var>soversion</var>-dev</package>,
5172 or if you prefer only to support one development version at a
5173 time, <package><var>libraryname</var>-dev</package>.
5177 In case several development versions of a library exist, you may
5178 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5179 <ref id="conflicts">) to ensure that the user only installs one
5180 development version at a time (as different development versions are
5181 likely to have the same header files in them, which would cause a
5182 filename clash if both were unpacked).
5186 The development package should contain a symlink for the associated
5187 shared library without a version number. For example, the
5188 <package>libgdbm-dev</package> package should include a symlink
5189 from <file>/usr/lib/libgdbm.so</file> to
5190 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5191 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5192 <file>libgdbm.so</file> when compiling dynamically.
5196 <sect id="sharedlibs-intradeps">
5197 <heading>Dependencies between the packages of the same library</heading>
5200 Typically the development version should have an exact
5201 version dependency on the runtime library, to make sure that
5202 compilation and linking happens correctly. The
5203 <tt>${binary:Version}</tt> substitution variable can be
5204 useful for this purpose.
5206 Previously, <tt>${Source-Version}</tt> was used, but its name
5207 was confusing and it has been deprecated since dpkg 1.13.19.
5212 <sect id="sharedlibs-shlibdeps">
5213 <heading>Dependencies between the library and other packages -
5214 the <tt>shlibs</tt> system</heading>
5217 If a package contains a binary or library which links to a
5218 shared library, we must ensure that when the package is
5219 installed on the system, all of the libraries needed are
5220 also installed. This requirement led to the creation of the
5221 <tt>shlibs</tt> system, which is very simple in its design:
5222 any package which <em>provides</em> a shared library also
5223 provides information on the package dependencies required to
5224 ensure the presence of this library, and any package which
5225 <em>uses</em> a shared library uses this information to
5226 determine the dependencies it requires. The files which
5227 contain the mapping from shared libraries to the necessary
5228 dependency information are called <file>shlibs</file> files.
5232 Thus, when a package is built which contains any shared
5233 libraries, it must provide a <file>shlibs</file> file for other
5234 packages to use, and when a package is built which contains
5235 any shared libraries or compiled binaries, it must run
5236 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5237 on these to determine the libraries used and hence the
5238 dependencies needed by this package.<footnote>
5240 In the past, the shared libraries linked to were
5241 determined by calling <prgn>ldd</prgn>, but now
5242 <prgn>objdump</prgn> is used to do this. The only
5243 change this makes to package building is that
5244 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
5245 libraries, whereas in the past this was unnecessary.
5246 The rest of this footnote explains the advantage that
5251 We say that a binary <tt>foo</tt> <em>directly</em> uses
5252 a library <tt>libbar</tt> if it is explicitly linked
5253 with that library (that is, it uses the flag
5254 <tt>-lbar</tt> during the linking stage). Other
5255 libraries that are needed by <tt>libbar</tt> are linked
5256 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5257 linker will load them automatically when it loads
5258 <tt>libbar</tt>. A package should depend on
5259 the libraries it directly uses, and the dependencies for
5260 those libraries should automatically pull in the other
5265 Unfortunately, the <prgn>ldd</prgn> program shows both
5266 the directly and indirectly used libraries, meaning that
5267 the dependencies determined included both direct and
5268 indirect dependencies. The use of <prgn>objdump</prgn>
5269 avoids this problem by determining only the directly
5274 A good example of where this helps is the following. We
5275 could update <tt>libimlib</tt> with a new version that
5276 supports a new graphics format called dgf (but retaining
5277 the same major version number). If we used the old
5278 <prgn>ldd</prgn> method, every package that uses
5279 <tt>libimlib</tt> would need to be recompiled so it
5280 would also depend on <tt>libdgf</tt> or it wouldn't run
5281 due to missing symbols. However with the new system,
5282 packages using <tt>libimlib</tt> can rely on
5283 <tt>libimlib</tt> itself having the dependency on
5284 <tt>libdgf</tt> and so they would not need rebuilding.
5290 In the following sections, we will first describe where the
5291 various <tt>shlibs</tt> files are to be found, then how to
5292 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5293 file format and how to create them if your package contains a
5298 <heading>The <tt>shlibs</tt> files present on the system</heading>
5301 There are several places where <tt>shlibs</tt> files are
5302 found. The following list gives them in the order in which
5304 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5305 (The first one which gives the required information is used.)
5311 <p><file>debian/shlibs.local</file></p>
5314 This lists overrides for this package. Its use is
5315 described below (see <ref id="shlibslocal">).
5320 <p><file>/etc/dpkg/shlibs.override</file></p>
5323 This lists global overrides. This list is normally
5324 empty. It is maintained by the local system
5330 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5333 When packages are being built, any
5334 <file>debian/shlibs</file> files are copied into the
5335 control file area of the temporary build directory and
5336 given the name <file>shlibs</file>. These files give
5337 details of any shared libraries included in the
5339 An example may help here. Let us say that the
5340 source package <tt>foo</tt> generates two binary
5341 packages, <tt>libfoo2</tt> and
5342 <tt>foo-runtime</tt>. When building the binary
5343 packages, the two packages are created in the
5344 directories <file>debian/libfoo2</file> and
5345 <file>debian/foo-runtime</file> respectively.
5346 (<file>debian/tmp</file> could be used instead of one
5347 of these.) Since <tt>libfoo2</tt> provides the
5348 <tt>libfoo</tt> shared library, it will require a
5349 <tt>shlibs</tt> file, which will be installed in
5350 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
5352 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
5353 when <prgn>dpkg-shlibdeps</prgn> is run on the
5355 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
5357 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5358 determine whether <tt>foo-prog</tt>'s library
5359 dependencies are satisfied by any of the libraries
5360 provided by <tt>libfoo2</tt>. For this reason,
5361 <prgn>dpkg-shlibdeps</prgn> must only be run once
5362 all of the individual binary packages'
5363 <tt>shlibs</tt> files have been installed into the
5370 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5373 These are the <file>shlibs</file> files corresponding to
5374 all of the packages installed on the system, and are
5375 maintained by the relevant package maintainers.
5380 <p><file>/etc/dpkg/shlibs.default</file></p>
5383 This file lists any shared libraries whose packages
5384 have failed to provide correct <file>shlibs</file> files.
5385 It was used when the <file>shlibs</file> setup was first
5386 introduced, but it is now normally empty. It is
5387 maintained by the <tt>dpkg</tt> maintainer.
5395 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5396 <file>shlibs</file> files</heading>
5400 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5401 into your <file>debian/rules</file> file. If your package
5402 contains only compiled binaries and libraries (but no scripts),
5403 you can use a command such as:
5404 <example compact="compact">
5405 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5406 debian/tmp/usr/lib/*
5408 Otherwise, you will need to explicitly list the compiled
5409 binaries and libraries.<footnote>
5410 If you are using <tt>debhelper</tt>, the
5411 <prgn>dh_shlibdeps</prgn> program will do this work for
5412 you. It will also correctly handle multi-binary
5418 This command puts the dependency information into the
5419 <file>debian/substvars</file> file, which is then used by
5420 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5421 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5422 field in the control file for this to work.
5426 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
5427 done. If it does complain you might need to create your own
5428 <file>debian/shlibs.local</file> file, as explained below (see
5429 <ref id="shlibslocal">).
5433 If you have multiple binary packages, you will need to call
5434 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5435 compiled libraries or binaries. In such a case, you will
5436 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5437 utilities to specify a different <file>substvars</file> file.
5441 If you are creating a udeb for use in the Debian Installer,
5442 you will need to specify that <prgn>dpkg-shlibdeps</prgn>
5443 should use the dependency line of type <tt>udeb</tt> by
5444 adding the <tt>-tudeb</tt> option<footnote>
5445 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5446 will automatically add this option if it knows it is
5448 </footnote>. If there is no dependency line of type <tt>udeb</tt>
5449 in the <file>shlibs</file> file, <prgn>dpkg-shlibdeps</prgn> will
5450 fall back to the regular dependency line.
5454 For more details on dpkg-shlibdeps, please see
5455 <ref id="pkg-dpkg-shlibdeps"> and
5456 <manref name="dpkg-shlibdeps" section="1">.
5461 <heading>The <file>shlibs</file> File Format</heading>
5464 Each <file>shlibs</file> file has the same format. Lines
5465 beginning with <tt>#</tt> are considered to be comments and
5466 are ignored. Each line is of the form:
5467 <example compact="compact">
5468 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5473 We will explain this by reference to the example of the
5474 <tt>zlib1g</tt> package, which (at the time of writing)
5475 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5479 <var>type</var> is an optional element that indicates the type
5480 of package for which the line is valid. The only type currently
5481 in use is <tt>udeb</tt>. The colon and space after the type are
5486 <var>library-name</var> is the name of the shared library,
5487 in this case <tt>libz</tt>. (This must match the name part
5488 of the soname, see below.)
5492 <var>soname-version</var> is the version part of the soname of
5493 the library. The soname is the thing that must exactly match
5494 for the library to be recognized by the dynamic linker, and is
5496 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5497 example, <tt>libz.so.1</tt>.<footnote>
5498 This can be determined using the command
5499 <example compact="compact">
5500 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5503 The version part is the part which comes after
5504 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
5508 <var>dependencies</var> has the same syntax as a dependency
5509 field in a binary package control file. It should give
5510 details of which packages are required to satisfy a binary
5511 built against the version of the library contained in the
5512 package. See <ref id="depsyntax"> for details.
5516 In our example, if the first version of the <tt>zlib1g</tt>
5517 package which contained a minor number of at least
5518 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5519 <tt>shlibs</tt> entry for this library could say:
5520 <example compact="compact">
5521 libz 1 zlib1g (>= 1:1.1.3)
5523 The version-specific dependency is to avoid warnings from
5524 the dynamic linker about using older shared libraries with
5529 As zlib1g also provides a udeb containing the shared library,
5530 there would also be a second line:
5531 <example compact="compact">
5532 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5538 <heading>Providing a <file>shlibs</file> file</heading>
5541 If your package provides a shared library, you need to create
5542 a <file>shlibs</file> file following the format described above.
5543 It is usual to call this file <file>debian/shlibs</file> (but if
5544 you have multiple binary packages, you might want to call it
5545 <file>debian/shlibs.<var>package</var></file> instead). Then
5546 let <file>debian/rules</file> install it in the control area:
5547 <example compact="compact">
5548 install -m644 debian/shlibs debian/tmp/DEBIAN
5550 or, in the case of a multi-binary package:
5551 <example compact="compact">
5552 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5554 An alternative way of doing this is to create the
5555 <file>shlibs</file> file in the control area directly from
5556 <file>debian/rules</file> without using a <file>debian/shlibs</file>
5557 file at all,<footnote>
5558 This is what <prgn>dh_makeshlibs</prgn> in the
5559 <tt>debhelper</tt> suite does. If your package also has a udeb
5560 that provides a shared library, <prgn>dh_makeshlibs</prgn> can
5561 automatically generate the <tt>udeb:</tt> lines if you specify
5562 the name of the udeb with the <tt>--add-udeb</tt> option.
5564 since the <file>debian/shlibs</file> file itself is ignored by
5565 <prgn>dpkg-shlibdeps</prgn>.
5569 As <prgn>dpkg-shlibdeps</prgn> reads the
5570 <file>DEBIAN/shlibs</file> files in all of the binary packages
5571 being built from this source package, all of the
5572 <file>DEBIAN/shlibs</file> files should be installed before
5573 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5578 <sect1 id="shlibslocal">
5579 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
5582 This file is intended only as a <em>temporary</em> fix if
5583 your binaries or libraries depend on a library whose package
5584 does not yet provide a correct <file>shlibs</file> file.
5588 We will assume that you are trying to package a binary
5589 <tt>foo</tt>. When you try running
5590 <prgn>dpkg-shlibdeps</prgn> you get the following error
5591 message (<tt>-O</tt> displays the dependency information on
5592 <tt>stdout</tt> instead of writing it to
5593 <tt>debian/substvars</tt>, and the lines have been wrapped
5594 for ease of reading):
5595 <example compact="compact">
5596 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
5597 dpkg-shlibdeps: warning: unable to find dependency
5598 information for shared library libbar (soname 1,
5599 path /usr/lib/libbar.so.1, dependency field Depends)
5600 shlibs:Depends=libc6 (>= 2.2.2-2)
5602 You can then run <prgn>ldd</prgn> on the binary to find the
5603 full location of the library concerned:
5604 <example compact="compact">
5606 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5607 libc.so.6 => /lib/libc.so.6 (0x40032000)
5608 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5610 So the <prgn>foo</prgn> binary depends on the
5611 <prgn>libbar</prgn> shared library, but no package seems to
5612 provide a <file>*.shlibs</file> file handling
5613 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5614 determine the package responsible:
5615 <example compact="compact">
5616 $ dpkg -S /usr/lib/libbar.so.1
5617 bar1: /usr/lib/libbar.so.1
5618 $ dpkg -s bar1 | grep Version
5621 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5622 is the one we are using. Now we can file a bug against the
5623 <tt>bar1</tt> package and create our own
5624 <file>debian/shlibs.local</file> to locally fix the problem.
5625 Including the following line into your
5626 <file>debian/shlibs.local</file> file:
5627 <example compact="compact">
5628 libbar 1 bar1 (>= 1.0-1)
5630 should allow the package build to work.
5634 As soon as the maintainer of <tt>bar1</tt> provides a
5635 correct <file>shlibs</file> file, you should remove this line
5636 from your <file>debian/shlibs.local</file> file. (You should
5637 probably also then have a versioned <tt>Build-Depends</tt>
5638 on <tt>bar1</tt> to help ensure that others do not have the
5639 same problem building your package.)
5648 <chapt id="opersys"><heading>The Operating System</heading>
5651 <heading>File system hierarchy</heading>
5655 <heading>File System Structure</heading>
5658 The location of all installed files and directories must
5659 comply with the Filesystem Hierarchy Standard (FHS),
5660 version 2.3, with the exceptions noted below, and except
5661 where doing so would violate other terms of Debian
5662 Policy. The following exceptions to the FHS apply:
5667 The optional rules related to user specific
5668 configuration files for applications are stored in
5669 the user's home directory are relaxed. It is
5670 recommended that such files start with the
5671 '<tt>.</tt>' character (a "dot file"), and if an
5672 application needs to create more than one dot file
5673 then the preferred placement is in a subdirectory
5674 with a name starting with a '.' character, (a "dot
5675 directory"). In this case it is recommended the
5676 configuration files not start with the '.'
5682 The requirement for amd64 to use <file>/lib64</file>
5683 for 64 bit binaries is removed.
5688 The requirement for object files, internal binaries, and
5689 libraries, including <file>libc.so.*</file>, to be located
5690 directly under <file>/lib{,32}</file> and
5691 <file>/usr/lib{,32}</file> is amended, permitting files
5692 to instead be installed to
5693 <file>/lib/<var>triplet</var></file> and
5694 <file>/usr/lib/<var>triplet</var></file>, where
5695 <tt><var>triplet</var></tt> is the value returned by
5696 <tt>dpkg-architecture -qDEB_HOST_GNU_TYPE</tt> for the
5697 architecture of the package. Packages may <em>not</em>
5698 install files to any <var>triplet</var> path other
5699 than the one matching the architecture of that package;
5700 for instance, an <tt>Architecture: amd64</tt> package
5701 containing 32-bit x86 libraries may not install these
5702 libraries to <file>/usr/lib/i486-linux-gnu</file>.
5704 This is necessary in order to reserve the directories for
5705 use in cross-installation of library packages from other
5706 architectures, as part of the planned deployment of
5711 Applications may also use a single subdirectory under
5712 <file>/usr/lib/<var>triplet</var></file>.
5715 The execution time linker/loader, ld*, must still be made
5716 available in the existing location under /lib or /lib64
5717 since this is part of the ELF ABI for the architecture.
5722 The requirement that
5723 <file>/usr/local/share/man</file> be "synonymous"
5724 with <file>/usr/local/man</file> is relaxed to a
5729 The requirement that windowmanagers with a single
5730 configuration file call it <file>system.*wmrc</file>
5731 is removed, as is the restriction that the window
5732 manager subdirectory be named identically to the
5733 window manager name itself.
5738 The requirement that boot manager configuration
5739 files live in <file>/etc</file>, or at least are
5740 symlinked there, is relaxed to a recommendation.
5745 The following directories in the root filesystem are
5746 additionally allowed: <file>/sys</file> and
5747 <file>/selinux</file>. <footnote>These directories
5748 are used as mount points to mount virtual filesystems
5749 to get access to kernel information.</footnote>
5756 The version of this document referred here can be
5757 found in the <tt>debian-policy</tt> package or on <url
5758 id="http://www.debian.org/doc/packaging-manuals/fhs/"
5759 name="FHS (Debian copy)"> alongside this manual (or, if
5760 you have the <package>debian-policy</package> installed,
5762 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5763 (local copy)">). The
5764 latest version, which may be a more recent version, may
5766 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5767 Specific questions about following the standard may be
5768 asked on the <tt>debian-devel</tt> mailing list, or
5769 referred to the FHS mailing list (see the
5770 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5776 <heading>Site-specific programs</heading>
5779 As mandated by the FHS, packages must not place any
5780 files in <file>/usr/local</file>, either by putting them in
5781 the file system archive to be unpacked by <prgn>dpkg</prgn>
5782 or by manipulating them in their maintainer scripts.
5786 However, the package may create empty directories below
5787 <file>/usr/local</file> so that the system administrator knows
5788 where to place site-specific files. These are not
5789 directories <em>in</em> <file>/usr/local</file>, but are
5790 children of directories in <file>/usr/local</file>. These
5791 directories (<file>/usr/local/*/dir/</file>)
5792 should be removed on package removal if they are
5797 Note that this applies only to
5798 directories <em>below</em> <file>/usr/local</file>,
5799 not <em>in</em> <file>/usr/local</file>. Packages must
5800 not create sub-directories in the
5801 directory <file>/usr/local</file> itself, except those
5802 listed in FHS, section 4.5. However, you may create
5803 directories below them as you wish. You must not remove
5804 any of the directories listed in 4.5, even if you created
5809 Since <file>/usr/local</file> can be mounted read-only from a
5810 remote server, these directories must be created and
5811 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5812 maintainer scripts and not be included in the
5813 <file>.deb</file> archive. These scripts must not fail if
5814 either of these operations fail.
5818 For example, the <tt>emacsen-common</tt> package could
5819 contain something like
5820 <example compact="compact">
5821 if [ ! -e /usr/local/share/emacs ]
5823 if mkdir /usr/local/share/emacs 2>/dev/null
5825 chown root:staff /usr/local/share/emacs
5826 chmod 2775 /usr/local/share/emacs
5830 in its <prgn>postinst</prgn> script, and
5831 <example compact="compact">
5832 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5833 rmdir /usr/local/share/emacs 2>/dev/null || true
5835 in the <prgn>prerm</prgn> script. (Note that this form is
5836 used to ensure that if the script is interrupted, the
5837 directory <file>/usr/local/share/emacs</file> will still be
5842 If you do create a directory in <file>/usr/local</file> for
5843 local additions to a package, you should ensure that
5844 settings in <file>/usr/local</file> take precedence over the
5845 equivalents in <file>/usr</file>.
5849 However, because <file>/usr/local</file> and its contents are
5850 for exclusive use of the local administrator, a package
5851 must not rely on the presence or absence of files or
5852 directories in <file>/usr/local</file> for normal operation.
5856 The <file>/usr/local</file> directory itself and all the
5857 subdirectories created by the package should (by default) have
5858 permissions 2775 (group-writable and set-group-id) and be
5859 owned by <tt>root:staff</tt>.
5864 <heading>The system-wide mail directory</heading>
5866 The system-wide mail directory
5867 is <file>/var/mail</file>. This directory is part of the
5868 base system and should not be owned by any particular mail
5869 agents. The use of the old
5870 location <file>/var/spool/mail</file> is deprecated, even
5871 though the spool may still be physically located there.
5877 <heading>Users and groups</heading>
5880 <heading>Introduction</heading>
5882 The Debian system can be configured to use either plain or
5887 Some user ids (UIDs) and group ids (GIDs) are reserved
5888 globally for use by certain packages. Because some
5889 packages need to include files which are owned by these
5890 users or groups, or need the ids compiled into binaries,
5891 these ids must be used on any Debian system only for the
5892 purpose for which they are allocated. This is a serious
5893 restriction, and we should avoid getting in the way of
5894 local administration policies. In particular, many sites
5895 allocate users and/or local system groups starting at 100.
5899 Apart from this we should have dynamically allocated ids,
5900 which should by default be arranged in some sensible
5901 order, but the behavior should be configurable.
5905 Packages other than <tt>base-passwd</tt> must not modify
5906 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5907 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5912 <heading>UID and GID classes</heading>
5914 The UID and GID numbers are divided into classes as
5920 Globally allocated by the Debian project, the same
5921 on every Debian system. These ids will appear in
5922 the <file>passwd</file> and <file>group</file> files of all
5923 Debian systems, new ids in this range being added
5924 automatically as the <tt>base-passwd</tt> package is
5929 Packages which need a single statically allocated
5930 uid or gid should use one of these; their
5931 maintainers should ask the <tt>base-passwd</tt>
5939 Dynamically allocated system users and groups.
5940 Packages which need a user or group, but can have
5941 this user or group allocated dynamically and
5942 differently on each system, should use <tt>adduser
5943 --system</tt> to create the group and/or user.
5944 <prgn>adduser</prgn> will check for the existence of
5945 the user or group, and if necessary choose an unused
5946 id based on the ranges specified in
5947 <file>adduser.conf</file>.
5951 <tag>1000-59999:</tag>
5954 Dynamically allocated user accounts. By default
5955 <prgn>adduser</prgn> will choose UIDs and GIDs for
5956 user accounts in this range, though
5957 <file>adduser.conf</file> may be used to modify this
5962 <tag>60000-64999:</tag>
5965 Globally allocated by the Debian project, but only
5966 created on demand. The ids are allocated centrally
5967 and statically, but the actual accounts are only
5968 created on users' systems on demand.
5972 These ids are for packages which are obscure or
5973 which require many statically-allocated ids. These
5974 packages should check for and create the accounts in
5975 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5976 <prgn>adduser</prgn> if it has this facility) if
5977 necessary. Packages which are likely to require
5978 further allocations should have a "hole" left after
5979 them in the allocation, to give them room to
5984 <tag>65000-65533:</tag>
5992 User <tt>nobody</tt>. The corresponding gid refers
5993 to the group <tt>nogroup</tt>.
6000 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
6001 not</em> be used, because it is the error return
6010 <sect id="sysvinit">
6011 <heading>System run levels and <file>init.d</file> scripts</heading>
6013 <sect1 id="/etc/init.d">
6014 <heading>Introduction</heading>
6017 The <file>/etc/init.d</file> directory contains the scripts
6018 executed by <prgn>init</prgn> at boot time and when the
6019 init state (or "runlevel") is changed (see <manref
6020 name="init" section="8">).
6024 There are at least two different, yet functionally
6025 equivalent, ways of handling these scripts. For the sake
6026 of simplicity, this document describes only the symbolic
6027 link method. However, it must not be assumed by maintainer
6028 scripts that this method is being used, and any automated
6029 manipulation of the various runlevel behaviors by
6030 maintainer scripts must be performed using
6031 <prgn>update-rc.d</prgn> as described below and not by
6032 manually installing or removing symlinks. For information
6033 on the implementation details of the other method,
6034 implemented in the <tt>file-rc</tt> package, please refer
6035 to the documentation of that package.
6039 These scripts are referenced by symbolic links in the
6040 <file>/etc/rc<var>n</var>.d</file> directories. When changing
6041 runlevels, <prgn>init</prgn> looks in the directory
6042 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
6043 execute, where <tt><var>n</var></tt> is the runlevel that
6044 is being changed to, or <tt>S</tt> for the boot-up
6049 The names of the links all have the form
6050 <file>S<var>mm</var><var>script</var></file> or
6051 <file>K<var>mm</var><var>script</var></file> where
6052 <var>mm</var> is a two-digit number and <var>script</var>
6053 is the name of the script (this should be the same as the
6054 name of the actual script in <file>/etc/init.d</file>).
6058 When <prgn>init</prgn> changes runlevel first the targets
6059 of the links whose names start with a <tt>K</tt> are
6060 executed, each with the single argument <tt>stop</tt>,
6061 followed by the scripts prefixed with an <tt>S</tt>, each
6062 with the single argument <tt>start</tt>. (The links are
6063 those in the <file>/etc/rc<var>n</var>.d</file> directory
6064 corresponding to the new runlevel.) The <tt>K</tt> links
6065 are responsible for killing services and the <tt>S</tt>
6066 link for starting services upon entering the runlevel.
6070 For example, if we are changing from runlevel 2 to
6071 runlevel 3, init will first execute all of the <tt>K</tt>
6072 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
6073 all of the <tt>S</tt> prefixed scripts in that directory.
6074 The links starting with <tt>K</tt> will cause the
6075 referred-to file to be executed with an argument of
6076 <tt>stop</tt>, and the <tt>S</tt> links with an argument
6081 The two-digit number <var>mm</var> is used to determine
6082 the order in which to run the scripts: low-numbered links
6083 have their scripts run first. For example, the
6084 <tt>K20</tt> scripts will be executed before the
6085 <tt>K30</tt> scripts. This is used when a certain service
6086 must be started before another. For example, the name
6087 server <prgn>bind</prgn> might need to be started before
6088 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
6089 can set up its access lists. In this case, the script
6090 that starts <prgn>bind</prgn> would have a lower number
6091 than the script that starts <prgn>inn</prgn> so that it
6093 <example compact="compact">
6100 The two runlevels 0 (halt) and 6 (reboot) are slightly
6101 different. In these runlevels, the links with an
6102 <tt>S</tt> prefix are still called after those with a
6103 <tt>K</tt> prefix, but they too are called with the single
6104 argument <tt>stop</tt>.
6108 <sect1 id="writing-init">
6109 <heading>Writing the scripts</heading>
6112 Packages that include daemons for system services should
6113 place scripts in <file>/etc/init.d</file> to start or stop
6114 services at boot time or during a change of runlevel.
6115 These scripts should be named
6116 <file>/etc/init.d/<var>package</var></file>, and they should
6117 accept one argument, saying what to do:
6120 <tag><tt>start</tt></tag>
6121 <item>start the service,</item>
6123 <tag><tt>stop</tt></tag>
6124 <item>stop the service,</item>
6126 <tag><tt>restart</tt></tag>
6127 <item>stop and restart the service if it's already running,
6128 otherwise start the service</item>
6130 <tag><tt>reload</tt></tag>
6131 <item><p>cause the configuration of the service to be
6132 reloaded without actually stopping and restarting
6135 <tag><tt>force-reload</tt></tag>
6136 <item>cause the configuration to be reloaded if the
6137 service supports this, otherwise restart the
6141 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
6142 <tt>force-reload</tt> options should be supported by all
6143 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
6148 The <file>init.d</file> scripts must ensure that they will
6149 behave sensibly (i.e., returning success and not starting
6150 multiple copies of a service) if invoked with <tt>start</tt>
6151 when the service is already running, or with <tt>stop</tt>
6152 when it isn't, and that they don't kill unfortunately-named
6153 user processes. The best way to achieve this is usually to
6154 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
6159 Be careful of using <tt>set -e</tt> in <file>init.d</file>
6160 scripts. Writing correct <file>init.d</file> scripts requires
6161 accepting various error exit statuses when daemons are already
6162 running or already stopped without aborting
6163 the <file>init.d</file> script, and common <file>init.d</file>
6164 function libraries are not safe to call with <tt>set -e</tt>
6166 <tt>/lib/lsb/init-functions</tt>, which assists in writing
6167 LSB-compliant init scripts, may fail if <tt>set -e</tt> is
6168 in effect and echoing status messages to the console fails,
6170 </footnote>. For <tt>init.d</tt> scripts, it's often easier
6171 to not use <tt>set -e</tt> and instead check the result of
6172 each command separately.
6176 If a service reloads its configuration automatically (as
6177 in the case of <prgn>cron</prgn>, for example), the
6178 <tt>reload</tt> option of the <file>init.d</file> script
6179 should behave as if the configuration has been reloaded
6184 The <file>/etc/init.d</file> scripts must be treated as
6185 configuration files, either (if they are present in the
6186 package, that is, in the .deb file) by marking them as
6187 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
6188 by managing them correctly in the maintainer scripts (see
6189 <ref id="config-files">). This is important since we want
6190 to give the local system administrator the chance to adapt
6191 the scripts to the local system, e.g., to disable a
6192 service without de-installing the package, or to specify
6193 some special command line options when starting a service,
6194 while making sure their changes aren't lost during the next
6199 These scripts should not fail obscurely when the
6200 configuration files remain but the package has been
6201 removed, as configuration files remain on the system after
6202 the package has been removed. Only when <prgn>dpkg</prgn>
6203 is executed with the <tt>--purge</tt> option will
6204 configuration files be removed. In particular, as the
6205 <file>/etc/init.d/<var>package</var></file> script itself is
6206 usually a <tt>conffile</tt>, it will remain on the system
6207 if the package is removed but not purged. Therefore, you
6208 should include a <tt>test</tt> statement at the top of the
6210 <example compact="compact">
6211 test -f <var>program-executed-later-in-script</var> || exit 0
6216 Often there are some variables in the <file>init.d</file>
6217 scripts whose values control the behavior of the scripts,
6218 and which a system administrator is likely to want to
6219 change. As the scripts themselves are frequently
6220 <tt>conffile</tt>s, modifying them requires that the
6221 administrator merge in their changes each time the package
6222 is upgraded and the <tt>conffile</tt> changes. To ease
6223 the burden on the system administrator, such configurable
6224 values should not be placed directly in the script.
6225 Instead, they should be placed in a file in
6226 <file>/etc/default</file>, which typically will have the same
6227 base name as the <file>init.d</file> script. This extra file
6228 should be sourced by the script when the script runs. It
6229 must contain only variable settings and comments in SUSv3
6230 <prgn>sh</prgn> format. It may either be a
6231 <tt>conffile</tt> or a configuration file maintained by
6232 the package maintainer scripts. See <ref id="config-files">
6237 To ensure that vital configurable values are always
6238 available, the <file>init.d</file> script should set default
6239 values for each of the shell variables it uses, either
6240 before sourcing the <file>/etc/default/</file> file or
6241 afterwards using something like the <tt>:
6242 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6243 script must behave sensibly and not fail if the
6244 <file>/etc/default</file> file is deleted.
6248 <file>/var/run</file> and <file>/var/lock</file> may be mounted
6249 as temporary filesystems<footnote>
6250 For example, using the <tt>RAMRUN</tt> and <tt>RAMLOCK</tt>
6251 options in <file>/etc/default/rcS</file>.
6252 </footnote>, so the <file>init.d</file> scripts must handle this
6253 correctly. This will typically amount to creating any required
6254 subdirectories dynamically when the <file>init.d</file> script
6255 is run, rather than including them in the package and relying on
6256 <prgn>dpkg</prgn> to create them.
6261 <heading>Interfacing with the initscript system</heading>
6264 Maintainers should use the abstraction layer provided by
6265 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6266 programs to deal with initscripts in their packages'
6267 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6268 and <prgn>postrm</prgn>.
6272 Directly managing the /etc/rc?.d links and directly
6273 invoking the <file>/etc/init.d/</file> initscripts should
6274 be done only by packages providing the initscript
6275 subsystem (such as <prgn>sysv-rc</prgn> and
6276 <prgn>file-rc</prgn>).
6280 <heading>Managing the links</heading>
6283 The program <prgn>update-rc.d</prgn> is provided for
6284 package maintainers to arrange for the proper creation and
6285 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6286 or their functional equivalent if another method is being
6287 used. This may be used by maintainers in their packages'
6288 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6292 You must not include any <file>/etc/rc<var>n</var>.d</file>
6293 symbolic links in the actual archive or manually create or
6294 remove the symbolic links in maintainer scripts; you must
6295 use the <prgn>update-rc.d</prgn> program instead. (The
6296 former will fail if an alternative method of maintaining
6297 runlevel information is being used.) You must not include
6298 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6299 in the archive either. (Only the <tt>sysvinit</tt>
6304 By default <prgn>update-rc.d</prgn> will start services in
6305 each of the multi-user state runlevels (2, 3, 4, and 5)
6306 and stop them in the halt runlevel (0), the single-user
6307 runlevel (1) and the reboot runlevel (6). The system
6308 administrator will have the opportunity to customize
6309 runlevels by simply adding, moving, or removing the
6310 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6311 symbolic links are being used, or by modifying
6312 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6317 To get the default behavior for your package, put in your
6318 <prgn>postinst</prgn> script
6319 <example compact="compact">
6320 update-rc.d <var>package</var> defaults
6322 and in your <prgn>postrm</prgn>
6323 <example compact="compact">
6324 if [ "$1" = purge ]; then
6325 update-rc.d <var>package</var> remove
6327 </example>. Note that if your package changes runlevels
6328 or priority, you may have to remove and recreate the links,
6329 since otherwise the old links may persist. Refer to the
6330 documentation of <prgn>update-rc.d</prgn>.
6334 This will use a default sequence number of 20. If it does
6335 not matter when or in which order the <file>init.d</file>
6336 script is run, use this default. If it does, then you
6337 should talk to the maintainer of the <prgn>sysvinit</prgn>
6338 package or post to <tt>debian-devel</tt>, and they will
6339 help you choose a number.
6343 For more information about using <tt>update-rc.d</tt>,
6344 please consult its man page <manref name="update-rc.d"
6350 <heading>Running initscripts</heading>
6352 The program <prgn>invoke-rc.d</prgn> is provided to make
6353 it easier for package maintainers to properly invoke an
6354 initscript, obeying runlevel and other locally-defined
6355 constraints that might limit a package's right to start,
6356 stop and otherwise manage services. This program may be
6357 used by maintainers in their packages' scripts.
6361 The package maintainer scripts must use
6362 <prgn>invoke-rc.d</prgn> to invoke the
6363 <file>/etc/init.d/*</file> initscripts, instead of
6364 calling them directly.
6368 By default, <prgn>invoke-rc.d</prgn> will pass any
6369 action requests (start, stop, reload, restart...) to the
6370 <file>/etc/init.d</file> script, filtering out requests
6371 to start or restart a service out of its intended
6376 Most packages will simply need to change:
6377 <example compact="compact">/etc/init.d/<package>
6378 <action></example> in their <prgn>postinst</prgn>
6379 and <prgn>prerm</prgn> scripts to:
6380 <example compact="compact">
6381 if which invoke-rc.d >/dev/null 2>&1; then
6382 invoke-rc.d <var>package</var> <action>
6384 /etc/init.d/<var>package</var> <action>
6390 A package should register its initscript services using
6391 <prgn>update-rc.d</prgn> before it tries to invoke them
6392 using <prgn>invoke-rc.d</prgn>. Invocation of
6393 unregistered services may fail.
6397 For more information about using
6398 <prgn>invoke-rc.d</prgn>, please consult its man page
6399 <manref name="invoke-rc.d" section="8">.
6405 <heading>Boot-time initialization</heading>
6408 There used to be another directory, <file>/etc/rc.boot</file>,
6409 which contained scripts which were run once per machine
6410 boot. This has been deprecated in favour of links from
6411 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6412 described in <ref id="/etc/init.d">. Packages must not
6413 place files in <file>/etc/rc.boot</file>.
6418 <heading>Example</heading>
6421 An example on which you can base your
6422 <file>/etc/init.d</file> scripts is found in
6423 <file>/etc/init.d/skeleton</file>.
6430 <heading>Console messages from <file>init.d</file> scripts</heading>
6433 This section describes the formats to be used for messages
6434 written to standard output by the <file>/etc/init.d</file>
6435 scripts. The intent is to improve the consistency of
6436 Debian's startup and shutdown look and feel. For this
6437 reason, please look very carefully at the details. We want
6438 the messages to have the same format in terms of wording,
6439 spaces, punctuation and case of letters.
6443 Here is a list of overall rules that should be used for
6444 messages generated by <file>/etc/init.d</file> scripts.
6450 The message should fit in one line (fewer than 80
6451 characters), start with a capital letter and end with
6452 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6456 If the script is performing some time consuming task in
6457 the background (not merely starting or stopping a
6458 program, for instance), an ellipsis (three dots:
6459 <tt>...</tt>) should be output to the screen, with no
6460 leading or tailing whitespace or line feeds.
6464 The messages should appear as if the computer is telling
6465 the user what it is doing (politely :-), but should not
6466 mention "it" directly. For example, instead of:
6467 <example compact="compact">
6468 I'm starting network daemons: nfsd mountd.
6470 the message should say
6471 <example compact="compact">
6472 Starting network daemons: nfsd mountd.
6479 <tt>init.d</tt> script should use the following standard
6480 message formats for the situations enumerated below.
6486 <p>When daemons are started</p>
6489 If the script starts one or more daemons, the output
6490 should look like this (a single line, no leading
6492 <example compact="compact">
6493 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6495 The <var>description</var> should describe the
6496 subsystem the daemon or set of daemons are part of,
6497 while <var>daemon-1</var> up to <var>daemon-n</var>
6498 denote each daemon's name (typically the file name of
6503 For example, the output of <file>/etc/init.d/lpd</file>
6505 <example compact="compact">
6506 Starting printer spooler: lpd.
6511 This can be achieved by saying
6512 <example compact="compact">
6513 echo -n "Starting printer spooler: lpd"
6514 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6517 in the script. If there are more than one daemon to
6518 start, the output should look like this:
6519 <example compact="compact">
6520 echo -n "Starting remote file system services:"
6521 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6522 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6523 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6526 This makes it possible for the user to see what is
6527 happening and when the final daemon has been started.
6528 Care should be taken in the placement of white spaces:
6529 in the example above the system administrators can
6530 easily comment out a line if they don't want to start
6531 a specific daemon, while the displayed message still
6537 <p>When a system parameter is being set</p>
6540 If you have to set up different system parameters
6541 during the system boot, you should use this format:
6542 <example compact="compact">
6543 Setting <var>parameter</var> to "<var>value</var>".
6548 You can use a statement such as the following to get
6550 <example compact="compact">
6551 echo "Setting DNS domainname to \"$domainname\"."
6556 Note that the same symbol (<tt>"</tt>) <!-- " --> is used
6557 for the left and right quotation marks. A grave accent
6558 (<tt>`</tt>) is not a quote character; neither is an
6559 apostrophe (<tt>'</tt>).
6564 <p>When a daemon is stopped or restarted</p>
6567 When you stop or restart a daemon, you should issue a
6568 message identical to the startup message, except that
6569 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6570 or <tt>Restarting</tt> respectively.
6574 For example, stopping the printer daemon will look like
6576 <example compact="compact">
6577 Stopping printer spooler: lpd.
6583 <p>When something is executed</p>
6586 There are several examples where you have to run a
6587 program at system startup or shutdown to perform a
6588 specific task, for example, setting the system's clock
6589 using <prgn>netdate</prgn> or killing all processes
6590 when the system shuts down. Your message should look
6592 <example compact="compact">
6593 Doing something very useful...done.
6595 You should print the <tt>done.</tt> immediately after
6596 the job has been completed, so that the user is
6597 informed why they have to wait. You can get this
6599 <example compact="compact">
6600 echo -n "Doing something very useful..."
6609 <p>When the configuration is reloaded</p>
6612 When a daemon is forced to reload its configuration
6613 files you should use the following format:
6614 <example compact="compact">
6615 Reloading <var>description</var> configuration...done.
6617 where <var>description</var> is the same as in the
6618 daemon starting message.
6626 <heading>Cron jobs</heading>
6629 Packages must not modify the configuration file
6630 <file>/etc/crontab</file>, and they must not modify the files in
6631 <file>/var/spool/cron/crontabs</file>.</p>
6634 If a package wants to install a job that has to be executed
6635 via cron, it should place a file with the name of the
6636 package in one or more of the following directories:
6637 <example compact="compact">
6643 As these directory names imply, the files within them are
6644 executed on an hourly, daily, weekly, or monthly basis,
6645 respectively. The exact times are listed in
6646 <file>/etc/crontab</file>.</p>
6649 All files installed in any of these directories must be
6650 scripts (e.g., shell scripts or Perl scripts) so that they
6651 can easily be modified by the local system administrator.
6652 In addition, they must be treated as configuration files.
6656 If a certain job has to be executed at some other frequency or
6657 at a specific time, the package should install a file
6658 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6659 same syntax as <file>/etc/crontab</file> and is processed by
6660 <prgn>cron</prgn> automatically. The file must also be
6661 treated as a configuration file. (Note that entries in the
6662 <file>/etc/cron.d</file> directory are not handled by
6663 <prgn>anacron</prgn>. Thus, you should only use this
6664 directory for jobs which may be skipped if the system is not
6667 Unlike <file>crontab</file> files described in the IEEE Std
6668 1003.1-2008 (POSIX.1) available from
6669 <url id="http://www.opengroup.org/onlinepubs/9699919799/"
6670 name="The Open Group">, the files in
6671 <file>/etc/cron.d</file> and the file
6672 <file>/etc/crontab</file> have seven fields; namely:
6674 <item>Minute [0,59]</item>
6675 <item>Hour [0,23]</item>
6676 <item>Day of the month [1,31]</item>
6677 <item>Month of the year [1,12]</item>
6678 <item>Day of the week ([0,6] with 0=Sunday)</item>
6679 <item>Username</item>
6680 <item>Command to be run</item>
6682 Ranges of numbers are allowed. Ranges are two numbers
6683 separated with a hyphen. The specified range is inclusive.
6684 Lists are allowed. A list is a set of numbers (or ranges)
6685 separated by commas. Step values can be used in conjunction
6690 The scripts or <tt>crontab</tt> entries in these directories should
6691 check if all necessary programs are installed before they
6692 try to execute them. Otherwise, problems will arise when a
6693 package was removed but not purged since configuration files
6694 are kept on the system in this situation.
6698 Any <tt>cron</tt> daemon must provide
6699 <file>/usr/bin/crontab</file> and support normal
6700 <tt>crontab</tt> entries as specified in POSIX. The daemon
6701 must also support names for days and months, ranges, and
6702 step values. It has to support <file>/etc/crontab</file>,
6703 and correctly execute the scripts in
6704 <file>/etc/cron.d</file>. The daemon must also correctly
6706 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>.
6711 <heading>Menus</heading>
6714 The Debian <tt>menu</tt> package provides a standard
6715 interface between packages providing applications and
6716 <em>menu programs</em> (either X window managers or
6717 text-based menu programs such as <prgn>pdmenu</prgn>).
6721 All packages that provide applications that need not be
6722 passed any special command line arguments for normal
6723 operation should register a menu entry for those
6724 applications, so that users of the <tt>menu</tt> package
6725 will automatically get menu entries in their window
6726 managers, as well in shells like <tt>pdmenu</tt>.
6730 Menu entries should follow the current menu policy.
6734 The menu policy can be found in the <tt>menu-policy</tt>
6735 files in the <tt>debian-policy</tt> package.
6736 It is also available from the Debian web mirrors at
6737 <tt><url name="/doc/packaging-manuals/menu-policy/"
6738 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6742 Please also refer to the <em>Debian Menu System</em>
6743 documentation that comes with the <package>menu</package>
6744 package for information about how to register your
6750 <heading>Multimedia handlers</heading>
6753 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6754 is a mechanism for encoding files and data streams and
6755 providing meta-information about them, in particular their
6756 type (e.g. audio or video) and format (e.g. PNG, HTML,
6761 Registration of MIME type handlers allows programs like mail
6762 user agents and web browsers to invoke these handlers to
6763 view, edit or display MIME types they don't support directly.
6767 Packages which provide the ability to view/show/play,
6768 compose, edit or print MIME types should register themselves
6769 as such following the current MIME support policy.
6773 The MIME support policy can be found in the <tt>mime-policy</tt>
6774 files in the <tt>debian-policy</tt> package.
6775 It is also available from the Debian web mirrors at
6776 <tt><url name="/doc/packaging-manuals/mime-policy/"
6777 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6783 <heading>Keyboard configuration</heading>
6786 To achieve a consistent keyboard configuration so that all
6787 applications interpret a keyboard event the same way, all
6788 programs in the Debian distribution must be configured to
6789 comply with the following guidelines.
6793 The following keys must have the specified interpretations:
6796 <tag><tt><--</tt></tag>
6797 <item>delete the character to the left of the cursor</item>
6799 <tag><tt>Delete</tt></tag>
6800 <item>delete the character to the right of the cursor</item>
6802 <tag><tt>Control+H</tt></tag>
6803 <item>emacs: the help prefix</item>
6806 The interpretation of any keyboard events should be
6807 independent of the terminal that is used, be it a virtual
6808 console, an X terminal emulator, an rlogin/telnet session,
6813 The following list explains how the different programs
6814 should be set up to achieve this:
6820 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6824 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6828 X translations are set up to make
6829 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6830 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6831 is the vt220 escape code for the "delete character"
6832 key). This must be done by loading the X resources
6833 using <prgn>xrdb</prgn> on all local X displays, not
6834 using the application defaults, so that the
6835 translation resources used correspond to the
6836 <prgn>xmodmap</prgn> settings.
6840 The Linux console is configured to make
6841 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6842 generate <tt>ESC [ 3 ~</tt>.
6846 X applications are configured so that <tt><</tt>
6847 deletes left, and <tt>Delete</tt> deletes right. Motif
6848 applications already work like this.
6852 Terminals should have <tt>stty erase ^?</tt> .
6856 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6857 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6858 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6862 Emacs is programmed to map <tt>KB_Backspace</tt> or
6863 the <tt>stty erase</tt> character to
6864 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6865 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6866 <tt>^H</tt> to <tt>help</tt> as always.
6870 Other applications use the <tt>stty erase</tt>
6871 character and <tt>kdch1</tt> for the two delete keys,
6872 with ASCII DEL being "delete previous character" and
6873 <tt>kdch1</tt> being "delete character under
6881 This will solve the problem except for the following
6888 Some terminals have a <tt><--</tt> key that cannot
6889 be made to produce anything except <tt>^H</tt>. On
6890 these terminals Emacs help will be unavailable on
6891 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6892 character takes precedence in Emacs, and has been set
6893 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6894 available) can be used instead.
6898 Some operating systems use <tt>^H</tt> for <tt>stty
6899 erase</tt>. However, modern telnet versions and all
6900 rlogin versions propagate <tt>stty</tt> settings, and
6901 almost all UNIX versions honour <tt>stty erase</tt>.
6902 Where the <tt>stty</tt> settings are not propagated
6903 correctly, things can be made to work by using
6904 <tt>stty</tt> manually.
6908 Some systems (including previous Debian versions) use
6909 <prgn>xmodmap</prgn> to arrange for both
6910 <tt><--</tt> and <tt>Delete</tt> to generate
6911 <tt>KB_Delete</tt>. We can change the behavior of
6912 their X clients using the same X resources that we use
6913 to do it for our own clients, or configure our clients
6914 using their resources when things are the other way
6915 around. On displays configured like this
6916 <tt>Delete</tt> will not work, but <tt><--</tt>
6921 Some operating systems have different <tt>kdch1</tt>
6922 settings in their <tt>terminfo</tt> database for
6923 <tt>xterm</tt> and others. On these systems the
6924 <tt>Delete</tt> key will not work correctly when you
6925 log in from a system conforming to our policy, but
6926 <tt><--</tt> will.
6933 <heading>Environment variables</heading>
6936 A program must not depend on environment variables to get
6937 reasonable defaults. (That's because these environment
6938 variables would have to be set in a system-wide
6939 configuration file like <file>/etc/profile</file>, which is not
6940 supported by all shells.)
6944 If a program usually depends on environment variables for its
6945 configuration, the program should be changed to fall back to
6946 a reasonable default configuration if these environment
6947 variables are not present. If this cannot be done easily
6948 (e.g., if the source code of a non-free program is not
6949 available), the program must be replaced by a small
6950 "wrapper" shell script which sets the environment variables
6951 if they are not already defined, and calls the original program.
6955 Here is an example of a wrapper script for this purpose:
6957 <example compact="compact">
6959 BAR=${BAR:-/var/lib/fubar}
6961 exec /usr/lib/foo/foo "$@"
6966 Furthermore, as <file>/etc/profile</file> is a configuration
6967 file of the <prgn>base-files</prgn> package, other packages must
6968 not put any environment variables or other commands into that
6973 <sect id="doc-base">
6974 <heading>Registering Documents using doc-base</heading>
6977 The <package>doc-base</package> package implements a
6978 flexible mechanism for handling and presenting
6979 documentation. The recommended practice is for every Debian
6980 package that provides online documentation (other than just
6981 manual pages) to register these documents with
6982 <package>doc-base</package> by installing a
6983 <package>doc-base</package> control file via the
6984 <prgn/install-docs/ script at installation time and
6985 de-register the manuals again when the package is removed.
6988 Please refer to the documentation that comes with the
6989 <package>doc-base</package> package for information and
6998 <heading>Files</heading>
7001 <heading>Binaries</heading>
7004 Two different packages must not install programs with
7005 different functionality but with the same filenames. (The
7006 case of two programs having the same functionality but
7007 different implementations is handled via "alternatives" or
7008 the "Conflicts" mechanism. See <ref id="maintscripts"> and
7009 <ref id="conflicts"> respectively.) If this case happens,
7010 one of the programs must be renamed. The maintainers should
7011 report this to the <tt>debian-devel</tt> mailing list and
7012 try to find a consensus about which program will have to be
7013 renamed. If a consensus cannot be reached, <em>both</em>
7014 programs must be renamed.
7018 By default, when a package is being built, any binaries
7019 created should include debugging information, as well as
7020 being compiled with optimization. You should also turn on
7021 as many reasonable compilation warnings as possible; this
7022 makes life easier for porters, who can then look at build
7023 logs for possible problems. For the C programming language,
7024 this means the following compilation parameters should be
7026 <example compact="compact">
7028 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
7030 INSTALL = install -s # (or use strip on the files in debian/tmp)
7035 Note that by default all installed binaries should be stripped,
7036 either by using the <tt>-s</tt> flag to
7037 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
7038 the binaries after they have been copied into
7039 <file>debian/tmp</file> but before the tree is made into a
7044 Although binaries in the build tree should be compiled with
7045 debugging information by default, it can often be difficult to
7046 debug programs if they are also subjected to compiler
7047 optimization. For this reason, it is recommended to support the
7048 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
7049 (see <ref id="debianrules-options">). This variable can contain
7050 several flags to change how a package is compiled and built.
7054 It is up to the package maintainer to decide what
7055 compilation options are best for the package. Certain
7056 binaries (such as computationally-intensive programs) will
7057 function better with certain flags (<tt>-O3</tt>, for
7058 example); feel free to use them. Please use good judgment
7059 here. Don't use flags for the sake of it; only use them
7060 if there is good reason to do so. Feel free to override
7061 the upstream author's ideas about which compilation
7062 options are best: they are often inappropriate for our
7068 <sect id="libraries">
7069 <heading>Libraries</heading>
7072 If the package is <strong>architecture: any</strong>, then
7073 the shared library compilation and linking flags must have
7074 <tt>-fPIC</tt>, or the package shall not build on some of
7075 the supported architectures<footnote>
7077 If you are using GCC, <tt>-fPIC</tt> produces code with
7078 relocatable position independent code, which is required for
7079 most architectures to create a shared library, with i386 and
7080 perhaps some others where non position independent code is
7081 permitted in a shared library.
7084 Position independent code may have a performance penalty,
7085 especially on <tt>i386</tt>. However, in most cases the
7086 speed penalty must be measured against the memory wasted on
7087 the few architectures where non position independent code is
7090 </footnote>. Any exception to this rule must be discussed on
7091 the mailing list <em>debian-devel@lists.debian.org</em>, and
7092 a rough consensus obtained. The reasons for not compiling
7093 with <tt>-fPIC</tt> flag must be recorded in the file
7094 <tt>README.Debian</tt>, and care must be taken to either
7095 restrict the architecture or arrange for <tt>-fPIC</tt> to
7096 be used on architectures where it is required.<footnote>
7098 Some of the reasons why this might be required is if the
7099 library contains hand crafted assembly code that is not
7100 relocatable, the speed penalty is excessive for compute
7101 intensive libs, and similar reasons.
7106 As to the static libraries, the common case is not to have
7107 relocatable code, since there is no benefit, unless in specific
7108 cases; therefore the static version must not be compiled
7109 with the <tt>-fPIC</tt> flag. Any exception to this rule
7110 should be discussed on the mailing list
7111 <em>debian-devel@lists.debian.org</em>, and the reasons for
7112 compiling with the <tt>-fPIC</tt> flag must be recorded in
7113 the file <tt>README.Debian</tt>. <footnote>
7115 Some of the reasons for linking static libraries with
7116 the <tt>-fPIC</tt> flag are if, for example, one needs a
7117 Perl API for a library that is under rapid development,
7118 and has an unstable API, so shared libraries are
7119 pointless at this phase of the library's development. In
7120 that case, since Perl needs a library with relocatable
7121 code, it may make sense to create a static library with
7122 relocatable code. Another reason cited is if you are
7123 distilling various libraries into a common shared
7124 library, like <tt>mklibs</tt> does in the Debian
7130 In other words, if both a shared and a static library is
7131 being built, each source unit (<tt>*.c</tt>, for example,
7132 for C files) will need to be compiled twice, for the normal
7136 You must specify the gcc option <tt>-D_REENTRANT</tt>
7137 when building a library (either static or shared) to make
7138 the library compatible with LinuxThreads.
7142 Although not enforced by the build tools, shared libraries
7143 must be linked against all libraries that they use symbols from
7144 in the same way that binaries are. This ensures the correct
7145 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
7146 system and guarantees that all libraries can be safely opened
7147 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
7148 option <tt>-Wl,-z,defs</tt> when building a shared library.
7149 Since this option enforces symbol resolution at build time,
7150 a missing library reference will be caught early as a fatal
7155 All installed shared libraries should be stripped with
7156 <example compact="compact">
7157 strip --strip-unneeded <var>your-lib</var>
7159 (The option <tt>--strip-unneeded</tt> makes
7160 <prgn>strip</prgn> remove only the symbols which aren't
7161 needed for relocation processing.) Shared libraries can
7162 function perfectly well when stripped, since the symbols for
7163 dynamic linking are in a separate part of the ELF object
7165 You might also want to use the options
7166 <tt>--remove-section=.comment</tt> and
7167 <tt>--remove-section=.note</tt> on both shared libraries
7168 and executables, and <tt>--strip-debug</tt> on static
7174 Note that under some circumstances it may be useful to
7175 install a shared library unstripped, for example when
7176 building a separate package to support debugging.
7180 Shared object files (often <file>.so</file> files) that are not
7181 public libraries, that is, they are not meant to be linked
7182 to by third party executables (binaries of other packages),
7183 should be installed in subdirectories of the
7184 <file>/usr/lib</file> directory. Such files are exempt from the
7185 rules that govern ordinary shared libraries, except that
7186 they must not be installed executable and should be
7188 A common example are the so-called "plug-ins",
7189 internal shared objects that are dynamically loaded by
7190 programs using <manref name="dlopen" section="3">.
7195 An ever increasing number of packages are using
7196 <prgn>libtool</prgn> to do their linking. The latest GNU
7197 libtools (>= 1.3a) can take advantage of the metadata in the
7198 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
7199 files). The main advantage of <prgn>libtool</prgn>'s
7200 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
7201 store and subsequently access metadata with respect to the
7202 libraries it builds. <prgn>libtool</prgn> will search for
7203 those files, which contain a lot of useful information about
7204 a library (such as library dependency information for static
7205 linking). Also, they're <em>essential</em> for programs
7206 using <tt>libltdl</tt>.<footnote>
7207 Although <prgn>libtool</prgn> is fully capable of
7208 linking against shared libraries which don't have
7209 <tt>.la</tt> files, as it is a mere shell script it can
7210 add considerably to the build time of a
7211 <prgn>libtool</prgn>-using package if that shell script
7212 has to derive all this information from first principles
7213 for each library every time it is linked. With the
7214 advent of <prgn>libtool</prgn> version 1.4 (and to a
7215 lesser extent <prgn>libtool</prgn> version 1.3), the
7216 <file>.la</file> files also store information about
7217 inter-library dependencies which cannot necessarily be
7218 derived after the <file>.la</file> file is deleted.
7223 Packages that use <prgn>libtool</prgn> to create shared
7224 libraries should include the <file>.la</file> files in the
7225 <tt>-dev</tt> package, unless the package relies on
7226 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
7227 the <tt>.la</tt> files must go in the run-time library
7232 You must make sure that you use only released versions of
7233 shared libraries to build your packages; otherwise other
7234 users will not be able to run your binaries
7235 properly. Producing source packages that depend on
7236 unreleased compilers is also usually a bad
7243 <heading>Shared libraries</heading>
7245 This section has moved to <ref id="sharedlibs">.
7251 <heading>Scripts</heading>
7254 All command scripts, including the package maintainer
7255 scripts inside the package and used by <prgn>dpkg</prgn>,
7256 should have a <tt>#!</tt> line naming the shell to be used
7261 In the case of Perl scripts this should be
7262 <tt>#!/usr/bin/perl</tt>.
7266 When scripts are installed into a directory in the system
7267 PATH, the script name should not include an extension such
7268 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7269 language currently used to implement it.
7272 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>) other than
7273 <file>init.d</file> scripts should almost certainly start
7274 with <tt>set -e</tt> so that errors are detected.
7275 <file>init.d</file> scripts are something of a special case, due
7276 to how frequently they need to call commands that are allowed to
7277 fail, and it may instead be easier to check the exit status of
7278 commands directly. See <ref id="writing-init"> for more
7279 information about writing <file>init.d</file> scripts.
7282 Every script should use <tt>set -e</tt> or check the exit status
7283 of <em>every</em> command.
7286 Scripts may assume that <file>/bin/sh</file> implements the
7287 SUSv3 Shell Command Language<footnote>
7288 Single UNIX Specification, version 3, which is also IEEE
7289 1003.1-2004 (POSIX), and is available on the World Wide Web
7290 from <url id="http://www.unix.org/version3/online.html"
7291 name="The Open Group"> after free
7292 registration.</footnote>
7293 plus the following additional features not mandated by
7295 These features are in widespread use in the Linux community
7296 and are implemented in all of bash, dash, and ksh, the most
7297 common shells users may wish to use as <file>/bin/sh</file>.
7300 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7301 must not generate a newline.</item>
7302 <item><tt>test</tt>, if implemented as a shell built-in, must
7303 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7305 <item><tt>local</tt> to create a scoped variable must be
7306 supported, including listing multiple variables in a single
7307 local command and assigning a value to a variable at the
7308 same time as localizing it. <tt>local</tt> may or
7309 may not preserve the variable value from an outer scope if
7310 no assignment is present. Uses such as:
7314 # ... use a, b, c, d ...
7317 must be supported and must set the value of <tt>c</tt> to
7321 If a shell script requires non-SUSv3 features from the shell
7322 interpreter other than those listed above, the appropriate shell
7323 must be specified in the first line of the script (e.g.,
7324 <tt>#!/bin/bash</tt>) and the package must depend on the package
7325 providing the shell (unless the shell package is marked
7326 "Essential", as in the case of <prgn>bash</prgn>).
7330 You may wish to restrict your script to SUSv3 features plus the
7331 above set when possible so that it may use <file>/bin/sh</file>
7332 as its interpreter. If your script works with <prgn>dash</prgn>
7333 (originally called <prgn>ash</prgn>), it probably complies with
7334 the above requirements, but if you are in doubt, use
7335 <file>/bin/bash</file>.
7339 Perl scripts should check for errors when making any
7340 system calls, including <tt>open</tt>, <tt>print</tt>,
7341 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7345 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7346 scripting languages. See <em>Csh Programming Considered
7347 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7348 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7349 If an upstream package comes with <prgn>csh</prgn> scripts
7350 then you must make sure that they start with
7351 <tt>#!/bin/csh</tt> and make your package depend on the
7352 <prgn>c-shell</prgn> virtual package.
7356 Any scripts which create files in world-writeable
7357 directories (e.g., in <file>/tmp</file>) must use a
7358 mechanism which will fail atomically if a file with the same
7359 name already exists.
7363 The Debian base system provides the <prgn>tempfile</prgn>
7364 and <prgn>mktemp</prgn> utilities for use by scripts for
7371 <heading>Symbolic links</heading>
7374 In general, symbolic links within a top-level directory
7375 should be relative, and symbolic links pointing from one
7376 top-level directory into another should be absolute. (A
7377 top-level directory is a sub-directory of the root
7378 directory <file>/</file>.)
7382 In addition, symbolic links should be specified as short as
7383 possible, i.e., link targets like <file>foo/../bar</file> are
7388 Note that when creating a relative link using
7389 <prgn>ln</prgn> it is not necessary for the target of the
7390 link to exist relative to the working directory you're
7391 running <prgn>ln</prgn> from, nor is it necessary to change
7392 directory to the directory where the link is to be made.
7393 Simply include the string that should appear as the target
7394 of the link (this will be a pathname relative to the
7395 directory in which the link resides) as the first argument
7400 For example, in your <prgn>Makefile</prgn> or
7401 <file>debian/rules</file>, you can do things like:
7402 <example compact="compact">
7403 ln -fs gcc $(prefix)/bin/cc
7404 ln -fs gcc debian/tmp/usr/bin/cc
7405 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7406 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7411 A symbolic link pointing to a compressed file should always
7412 have the same file extension as the referenced file. (For
7413 example, if a file <file>foo.gz</file> is referenced by a
7414 symbolic link, the filename of the link has to end with
7415 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7420 <heading>Device files</heading>
7423 Packages must not include device files or named pipes in the
7428 If a package needs any special device files that are not
7429 included in the base system, it must call
7430 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7431 after notifying the user<footnote>
7432 This notification could be done via a (low-priority)
7433 debconf message, or an echo (printf) statement.
7438 Packages must not remove any device files in the
7439 <prgn>postrm</prgn> or any other script. This is left to the
7440 system administrator.
7444 Debian uses the serial devices
7445 <file>/dev/ttyS*</file>. Programs using the old
7446 <file>/dev/cu*</file> devices should be changed to use
7447 <file>/dev/ttyS*</file>.
7451 Named pipes needed by the package must be created in
7452 the <prgn>postinst</prgn> script<footnote>
7453 It's better to use <prgn>mkfifo</prgn> rather
7454 than <prgn>mknod</prgn> to create named pipes so that
7455 automated checks for packages incorrectly creating device
7456 files with <prgn>mknod</prgn> won't have false positives.
7457 </footnote> and removed in
7458 the <prgn>prerm</prgn> or <prgn>postrm</prgn> script as
7463 <sect id="config-files">
7464 <heading>Configuration files</heading>
7467 <heading>Definitions</heading>
7471 <tag>configuration file</tag>
7473 A file that affects the operation of a program, or
7474 provides site- or host-specific information, or
7475 otherwise customizes the behavior of a program.
7476 Typically, configuration files are intended to be
7477 modified by the system administrator (if needed or
7478 desired) to conform to local policy or to provide
7479 more useful site-specific behavior.
7482 <tag><tt>conffile</tt></tag>
7484 A file listed in a package's <tt>conffiles</tt>
7485 file, and is treated specially by <prgn>dpkg</prgn>
7486 (see <ref id="configdetails">).
7492 The distinction between these two is important; they are
7493 not interchangeable concepts. Almost all
7494 <tt>conffile</tt>s are configuration files, but many
7495 configuration files are not <tt>conffiles</tt>.
7499 As noted elsewhere, <file>/etc/init.d</file> scripts,
7500 <file>/etc/default</file> files, scripts installed in
7501 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7502 configuration installed in <file>/etc/cron.d</file> must be
7503 treated as configuration files. In general, any script that
7504 embeds configuration information is de-facto a configuration
7505 file and should be treated as such.
7510 <heading>Location</heading>
7513 Any configuration files created or used by your package
7514 must reside in <file>/etc</file>. If there are several,
7515 consider creating a subdirectory of <file>/etc</file>
7516 named after your package.
7520 If your package creates or uses configuration files
7521 outside of <file>/etc</file>, and it is not feasible to modify
7522 the package to use <file>/etc</file> directly, put the files
7523 in <file>/etc</file> and create symbolic links to those files
7524 from the location that the package requires.
7529 <heading>Behavior</heading>
7532 Configuration file handling must conform to the following
7534 <list compact="compact">
7536 local changes must be preserved during a package
7540 configuration files must be preserved when the
7541 package is removed, and only deleted when the
7548 The easy way to achieve this behavior is to make the
7549 configuration file a <tt>conffile</tt>. This is
7550 appropriate only if it is possible to distribute a default
7551 version that will work for most installations, although
7552 some system administrators may choose to modify it. This
7553 implies that the default version will be part of the
7554 package distribution, and must not be modified by the
7555 maintainer scripts during installation (or at any other
7560 In order to ensure that local changes are preserved
7561 correctly, no package may contain or make hard links to
7562 conffiles.<footnote>
7563 Rationale: There are two problems with hard links.
7564 The first is that some editors break the link while
7565 editing one of the files, so that the two files may
7566 unwittingly become unlinked and different. The second
7567 is that <prgn>dpkg</prgn> might break the hard link
7568 while upgrading <tt>conffile</tt>s.
7573 The other way to do it is via the maintainer scripts. In
7574 this case, the configuration file must not be listed as a
7575 <tt>conffile</tt> and must not be part of the package
7576 distribution. If the existence of a file is required for
7577 the package to be sensibly configured it is the
7578 responsibility of the package maintainer to provide
7579 maintainer scripts which correctly create, update and
7580 maintain the file and remove it on purge. (See <ref
7581 id="maintainerscripts"> for more information.) These
7582 scripts must be idempotent (i.e., must work correctly if
7583 <prgn>dpkg</prgn> needs to re-run them due to errors
7584 during installation or removal), must cope with all the
7585 variety of ways <prgn>dpkg</prgn> can call maintainer
7586 scripts, must not overwrite or otherwise mangle the user's
7587 configuration without asking, must not ask unnecessary
7588 questions (particularly during upgrades), and must
7589 otherwise be good citizens.
7593 The scripts are not required to configure every possible
7594 option for the package, but only those necessary to get
7595 the package running on a given system. Ideally the
7596 sysadmin should not have to do any configuration other
7597 than that done (semi-)automatically by the
7598 <prgn>postinst</prgn> script.
7602 A common practice is to create a script called
7603 <file><var>package</var>-configure</file> and have the
7604 package's <prgn>postinst</prgn> call it if and only if the
7605 configuration file does not already exist. In certain
7606 cases it is useful for there to be an example or template
7607 file which the maintainer scripts use. Such files should
7608 be in <file>/usr/share/<var>package</var></file> or
7609 <file>/usr/lib/<var>package</var></file> (depending on whether
7610 they are architecture-independent or not). There should
7611 be symbolic links to them from
7612 <file>/usr/share/doc/<var>package</var>/examples</file> if
7613 they are examples, and should be perfectly ordinary
7614 <prgn>dpkg</prgn>-handled files (<em>not</em>
7615 configuration files).
7619 These two styles of configuration file handling must
7620 not be mixed, for that way lies madness:
7621 <prgn>dpkg</prgn> will ask about overwriting the file
7622 every time the package is upgraded.
7627 <heading>Sharing configuration files</heading>
7630 Packages which specify the same file as a
7631 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7632 with each other. (This is an instance of the general rule
7633 about not sharing files. Note that neither alternatives
7634 nor diversions are likely to be appropriate in this case;
7635 in particular, <prgn>dpkg</prgn> does not handle diverted
7636 <tt>conffile</tt>s well.)
7640 The maintainer scripts must not alter a <tt>conffile</tt>
7641 of <em>any</em> package, including the one the scripts
7646 If two or more packages use the same configuration file
7647 and it is reasonable for both to be installed at the same
7648 time, one of these packages must be defined as
7649 <em>owner</em> of the configuration file, i.e., it will be
7650 the package which handles that file as a configuration
7651 file. Other packages that use the configuration file must
7652 depend on the owning package if they require the
7653 configuration file to operate. If the other package will
7654 use the configuration file if present, but is capable of
7655 operating without it, no dependency need be declared.
7659 If it is desirable for two or more related packages to
7660 share a configuration file <em>and</em> for all of the
7661 related packages to be able to modify that configuration
7662 file, then the following should be done:
7663 <enumlist compact="compact">
7665 One of the related packages (the "owning" package)
7666 will manage the configuration file with maintainer
7667 scripts as described in the previous section.
7670 The owning package should also provide a program
7671 that the other packages may use to modify the
7675 The related packages must use the provided program
7676 to make any desired modifications to the
7677 configuration file. They should either depend on
7678 the core package to guarantee that the configuration
7679 modifier program is available or accept gracefully
7680 that they cannot modify the configuration file if it
7681 is not. (This is in addition to the fact that the
7682 configuration file may not even be present in the
7689 Sometimes it's appropriate to create a new package which
7690 provides the basic infrastructure for the other packages
7691 and which manages the shared configuration files. (The
7692 <tt>sgml-base</tt> package is a good example.)
7697 <heading>User configuration files ("dotfiles")</heading>
7700 The files in <file>/etc/skel</file> will automatically be
7701 copied into new user accounts by <prgn>adduser</prgn>.
7702 No other program should reference the files in
7703 <file>/etc/skel</file>.
7707 Therefore, if a program needs a dotfile to exist in
7708 advance in <file>$HOME</file> to work sensibly, that dotfile
7709 should be installed in <file>/etc/skel</file> and treated as a
7714 However, programs that require dotfiles in order to
7715 operate sensibly are a bad thing, unless they do create
7716 the dotfiles themselves automatically.
7720 Furthermore, programs should be configured by the Debian
7721 default installation to behave as closely to the upstream
7722 default behavior as possible.
7726 Therefore, if a program in a Debian package needs to be
7727 configured in some way in order to operate sensibly, that
7728 should be done using a site-wide configuration file placed
7729 in <file>/etc</file>. Only if the program doesn't support a
7730 site-wide default configuration and the package maintainer
7731 doesn't have time to add it may a default per-user file be
7732 placed in <file>/etc/skel</file>.
7736 <file>/etc/skel</file> should be as empty as we can make it.
7737 This is particularly true because there is no easy (or
7738 necessarily desirable) mechanism for ensuring that the
7739 appropriate dotfiles are copied into the accounts of
7740 existing users when a package is installed.
7746 <heading>Log files</heading>
7748 Log files should usually be named
7749 <file>/var/log/<var>package</var>.log</file>. If you have many
7750 log files, or need a separate directory for permission
7751 reasons (<file>/var/log</file> is writable only by
7752 <file>root</file>), you should usually create a directory named
7753 <file>/var/log/<var>package</var></file> and place your log
7758 Log files must be rotated occasionally so that they don't
7759 grow indefinitely; the best way to do this is to drop a log
7760 rotation configuration file into the directory
7761 <file>/etc/logrotate.d</file> and use the facilities provided by
7762 logrotate.<footnote>
7764 The traditional approach to log files has been to set up
7765 <em>ad hoc</em> log rotation schemes using simple shell
7766 scripts and cron. While this approach is highly
7767 customizable, it requires quite a lot of sysadmin work.
7768 Even though the original Debian system helped a little
7769 by automatically installing a system which can be used
7770 as a template, this was deemed not enough.
7774 The use of <prgn>logrotate</prgn>, a program developed
7775 by Red Hat, is better, as it centralizes log management.
7776 It has both a configuration file
7777 (<file>/etc/logrotate.conf</file>) and a directory where
7778 packages can drop their individual log rotation
7779 configurations (<file>/etc/logrotate.d</file>).
7782 Here is a good example for a logrotate config
7783 file (for more information see <manref name="logrotate"
7785 <example compact="compact">
7786 /var/log/foo/*.log {
7791 /etc/init.d/foo force-reload
7795 This rotates all files under <file>/var/log/foo</file>, saves 12
7796 compressed generations, and forces the daemon to reload its
7797 configuration information after the log rotation.
7801 Log files should be removed when the package is
7802 purged (but not when it is only removed). This should be
7803 done by the <prgn>postrm</prgn> script when it is called
7804 with the argument <tt>purge</tt> (see <ref
7805 id="removedetails">).
7810 <heading>Permissions and owners</heading>
7813 The rules in this section are guidelines for general use.
7814 If necessary you may deviate from the details below.
7815 However, if you do so you must make sure that what is done
7816 is secure and you should try to be as consistent as possible
7817 with the rest of the system. You should probably also
7818 discuss it on <prgn>debian-devel</prgn> first.
7822 Files should be owned by <tt>root:root</tt>, and made
7823 writable only by the owner and universally readable (and
7824 executable, if appropriate), that is mode 644 or 755.
7828 Directories should be mode 755 or (for group-writability)
7829 mode 2775. The ownership of the directory should be
7830 consistent with its mode: if a directory is mode 2775, it
7831 should be owned by the group that needs write access to
7834 When a package is upgraded, and the owner or permissions
7835 of a file included in the package has changed, dpkg
7836 arranges for the ownership and permissions to be
7837 correctly set upon installation. However, this does not
7838 extend to directories; the permissions and ownership of
7839 directories already on the system does not change on
7840 install or upgrade of packages. This makes sense, since
7841 otherwise common directories like <tt>/usr</tt> would
7842 always be in flux. To correctly change permissions of a
7843 directory the package owns, explicit action is required,
7844 usually in the <tt>postinst</tt> script. Care must be
7845 taken to handle downgrades as well, in that case.
7852 Setuid and setgid executables should be mode 4755 or 2755
7853 respectively, and owned by the appropriate user or group.
7854 They should not be made unreadable (modes like 4711 or
7855 2711 or even 4111); doing so achieves no extra security,
7856 because anyone can find the binary in the freely available
7857 Debian package; it is merely inconvenient. For the same
7858 reason you should not restrict read or execute permissions
7859 on non-set-id executables.
7863 Some setuid programs need to be restricted to particular
7864 sets of users, using file permissions. In this case they
7865 should be owned by the uid to which they are set-id, and by
7866 the group which should be allowed to execute them. They
7867 should have mode 4754; again there is no point in making
7868 them unreadable to those users who must not be allowed to
7873 It is possible to arrange that the system administrator can
7874 reconfigure the package to correspond to their local
7875 security policy by changing the permissions on a binary:
7876 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7877 described below.<footnote>
7878 Ordinary files installed by <prgn>dpkg</prgn> (as
7879 opposed to <tt>conffile</tt>s and other similar objects)
7880 normally have their permissions reset to the distributed
7881 permissions when the package is reinstalled. However,
7882 the use of <prgn>dpkg-statoverride</prgn> overrides this
7885 Another method you should consider is to create a group for
7886 people allowed to use the program(s) and make any setuid
7887 executables executable only by that group.
7891 If you need to create a new user or group for your package
7892 there are two possibilities. Firstly, you may need to
7893 make some files in the binary package be owned by this
7894 user or group, or you may need to compile the user or
7895 group id (rather than just the name) into the binary
7896 (though this latter should be avoided if possible, as in
7897 this case you need a statically allocated id).</p>
7900 If you need a statically allocated id, you must ask for a
7901 user or group id from the <tt>base-passwd</tt> maintainer,
7902 and must not release the package until you have been
7903 allocated one. Once you have been allocated one you must
7904 either make the package depend on a version of the
7905 <tt>base-passwd</tt> package with the id present in
7906 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7907 your package to create the user or group itself with the
7908 correct id (using <tt>adduser</tt>) in its
7909 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7910 the <prgn>postinst</prgn> is to be preferred if it is
7911 possible, otherwise a pre-dependency will be needed on the
7912 <tt>adduser</tt> package.)
7916 On the other hand, the program might be able to determine
7917 the uid or gid from the user or group name at runtime, so
7918 that a dynamically allocated id can be used. In this case
7919 you should choose an appropriate user or group name,
7920 discussing this on <prgn>debian-devel</prgn> and checking
7921 with the <package/base-passwd/ maintainer that it is unique and that
7922 they do not wish you to use a statically allocated id
7923 instead. When this has been checked you must arrange for
7924 your package to create the user or group if necessary using
7925 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7926 <prgn>postinst</prgn> script (again, the latter is to be
7927 preferred if it is possible).
7931 Note that changing the numeric value of an id associated
7932 with a name is very difficult, and involves searching the
7933 file system for all appropriate files. You need to think
7934 carefully whether a static or dynamic id is required, since
7935 changing your mind later will cause problems.
7938 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7940 This section is not intended as policy, but as a
7941 description of the use of <prgn>dpkg-statoverride</prgn>.
7945 If a system administrator wishes to have a file (or
7946 directory or other such thing) installed with owner and
7947 permissions different from those in the distributed Debian
7948 package, they can use the <prgn>dpkg-statoverride</prgn>
7949 program to instruct <prgn>dpkg</prgn> to use the different
7950 settings every time the file is installed. Thus the
7951 package maintainer should distribute the files with their
7952 normal permissions, and leave it for the system
7953 administrator to make any desired changes. For example, a
7954 daemon which is normally required to be setuid root, but
7955 in certain situations could be used without being setuid,
7956 should be installed setuid in the <tt>.deb</tt>. Then the
7957 local system administrator can change this if they wish.
7958 If there are two standard ways of doing it, the package
7959 maintainer can use <tt>debconf</tt> to find out the
7960 preference, and call <prgn>dpkg-statoverride</prgn> in the
7961 maintainer script if necessary to accommodate the system
7962 administrator's choice. Care must be taken during
7963 upgrades to not override an existing setting.
7967 Given the above, <prgn>dpkg-statoverride</prgn> is
7968 essentially a tool for system administrators and would not
7969 normally be needed in the maintainer scripts. There is
7970 one type of situation, though, where calls to
7971 <prgn>dpkg-statoverride</prgn> would be needed in the
7972 maintainer scripts, and that involves packages which use
7973 dynamically allocated user or group ids. In such a
7974 situation, something like the following idiom can be very
7975 helpful in the package's <prgn>postinst</prgn>, where
7976 <tt>sysuser</tt> is a dynamically allocated id:
7978 for i in /usr/bin/foo /usr/sbin/bar
7980 # only do something when no setting exists
7981 if ! dpkg-statoverride --list $i >/dev/null 2>&1
7983 #include: debconf processing, question about foo and bar
7984 if [ "$RET" = "true" ] ; then
7985 dpkg-statoverride --update --add sysuser root 4755 $i
7990 The corresponding code to remove the override when the package
7993 for i in /usr/bin/foo /usr/sbin/bar
7995 if dpkg-statoverride --list $i >/dev/null 2>&1
7997 dpkg-statoverride --remove $i
8007 <chapt id="customized-programs">
8008 <heading>Customized programs</heading>
8010 <sect id="arch-spec">
8011 <heading>Architecture specification strings</heading>
8014 If a program needs to specify an <em>architecture specification
8015 string</em> in some place, it should select one of the strings
8016 provided by <tt>dpkg-architecture -L</tt>. The strings are in
8017 the format <tt><var>os</var>-<var>arch</var></tt>, though the OS
8018 part is sometimes elided, as when the OS is Linux.
8022 Note that we don't want to use
8023 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
8024 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
8025 since this would make our programs incompatible with other
8026 Linux distributions. We also don't use something like
8027 <tt><var>arch</var>-unknown-linux</tt>, since the
8028 <tt>unknown</tt> does not look very good.
8031 <sect1 id="arch-wildcard-spec">
8032 <heading>Architecture wildcards</heading>
8035 A package may specify an architecture wildcard. Architecture
8036 wildcards are in the format <tt>any</tt> (which matches every
8037 architecture), <tt><var>os</var></tt>-any, or
8038 any-<tt><var>cpu</var></tt>. <footnote>
8039 Internally, the package system normalizes the GNU triplets
8040 and the Debian arches into Debian arch triplets (which are
8041 kind of inverted GNU triplets), with the first component of
8042 the triplet representing the libc and ABI in use, and then
8043 does matching against those triplets. However, such
8044 triplets are an internal implementation detail that should
8045 not be used by packages directly. The libc and ABI portion
8046 is handled internally by the package system based on
8047 the <var>os</var> and <var>cpu</var>.
8054 <heading>Daemons</heading>
8057 The configuration files <file>/etc/services</file>,
8058 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
8059 by the <prgn>netbase</prgn> package and must not be modified
8064 If a package requires a new entry in one of these files, the
8065 maintainer should get in contact with the
8066 <prgn>netbase</prgn> maintainer, who will add the entries
8067 and release a new version of the <prgn>netbase</prgn>
8072 The configuration file <file>/etc/inetd.conf</file> must not be
8073 modified by the package's scripts except via the
8074 <prgn>update-inetd</prgn> script or the
8075 <file>DebianNet.pm</file> Perl module. See their documentation
8076 for details on how to add entries.
8080 If a package wants to install an example entry into
8081 <file>/etc/inetd.conf</file>, the entry must be preceded with
8082 exactly one hash character (<tt>#</tt>). Such lines are
8083 treated as "commented out by user" by the
8084 <prgn>update-inetd</prgn> script and are not changed or
8085 activated during package updates.
8090 <heading>Using pseudo-ttys and modifying wtmp, utmp and
8094 Some programs need to create pseudo-ttys. This should be done
8095 using Unix98 ptys if the C library supports it. The resulting
8096 program must not be installed setuid root, unless that
8097 is required for other functionality.
8101 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
8102 <file>/var/log/lastlog</file> must be installed writable by
8103 group <tt>utmp</tt>. Programs which need to modify those
8104 files must be installed setgid <tt>utmp</tt>.
8109 <heading>Editors and pagers</heading>
8112 Some programs have the ability to launch an editor or pager
8113 program to edit or display a text document. Since there are
8114 lots of different editors and pagers available in the Debian
8115 distribution, the system administrator and each user should
8116 have the possibility to choose their preferred editor and
8121 In addition, every program should choose a good default
8122 editor/pager if none is selected by the user or system
8127 Thus, every program that launches an editor or pager must
8128 use the EDITOR or PAGER environment variable to determine
8129 the editor or pager the user wishes to use. If these
8130 variables are not set, the programs <file>/usr/bin/editor</file>
8131 and <file>/usr/bin/pager</file> should be used, respectively.
8135 These two files are managed through the <prgn>dpkg</prgn>
8136 "alternatives" mechanism. Thus every package providing an
8137 editor or pager must call the
8138 <prgn>update-alternatives</prgn> script to register these
8143 If it is very hard to adapt a program to make use of the
8144 EDITOR or PAGER variables, that program may be configured to
8145 use <file>/usr/bin/sensible-editor</file> and
8146 <file>/usr/bin/sensible-pager</file> as the editor or pager
8147 program respectively. These are two scripts provided in the
8148 <package>sensible-utils</package> package that check the EDITOR
8149 and PAGER variables and launch the appropriate program, and fall
8150 back to <file>/usr/bin/editor</file>
8151 and <file>/usr/bin/pager</file> if the variable is not set.
8155 A program may also use the VISUAL environment variable to
8156 determine the user's choice of editor. If it exists, it
8157 should take precedence over EDITOR. This is in fact what
8158 <file>/usr/bin/sensible-editor</file> does.
8162 It is not required for a package to depend on
8163 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
8164 package to provide such virtual packages.<footnote>
8165 The Debian base system already provides an editor and a
8171 <sect id="web-appl">
8172 <heading>Web servers and applications</heading>
8175 This section describes the locations and URLs that should
8176 be used by all web servers and web applications in the
8183 Cgi-bin executable files are installed in the
8185 <example compact="compact">
8186 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
8188 and should be referred to as
8189 <example compact="compact">
8190 http://localhost/cgi-bin/<var>cgi-bin-name</var>
8196 <p>Access to HTML documents</p>
8199 HTML documents for a package are stored in
8200 <file>/usr/share/doc/<var>package</var></file>
8201 and can be referred to as
8202 <example compact="compact">
8203 http://localhost/doc/<var>package</var>/<var>filename</var>
8208 The web server should restrict access to the document
8209 tree so that only clients on the same host can read
8210 the documents. If the web server does not support such
8211 access controls, then it should not provide access at
8212 all, or ask about providing access during installation.
8217 <p>Access to images</p>
8219 It is recommended that images for a package be stored
8220 in <tt>/usr/share/images/<var>package</var></tt> and
8221 may be referred to through an alias <tt>/images/</tt>
8224 http://localhost/images/<package>/<filename>
8231 <p>Web Document Root</p>
8234 Web Applications should try to avoid storing files in
8235 the Web Document Root. Instead they should use the
8236 /usr/share/doc/<var>package</var> directory for
8237 documents and register the Web Application via the
8238 <package>doc-base</package> package. If access to the
8239 web document root is unavoidable then use
8240 <example compact="compact">
8243 as the Document Root. This might be just a symbolic
8244 link to the location where the system administrator
8245 has put the real document root.
8248 <item><p>Providing httpd and/or httpd-cgi</p>
8250 All web servers should provide the virtual package
8251 <tt>httpd</tt>. If a web server has CGI support it should
8252 provide <tt>httpd-cgi</tt> additionally.
8255 All web applications which do not contain CGI scripts should
8256 depend on <tt>httpd</tt>, all those web applications which
8257 <tt>do</tt> contain CGI scripts, should depend on
8265 <sect id="mail-transport-agents">
8266 <heading>Mail transport, delivery and user agents</heading>
8269 Debian packages which process electronic mail, whether mail
8270 user agents (MUAs) or mail transport agents (MTAs), must
8271 ensure that they are compatible with the configuration
8272 decisions below. Failure to do this may result in lost
8273 mail, broken <tt>From:</tt> lines, and other serious brain
8278 The mail spool is <file>/var/mail</file> and the interface to
8279 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8280 the FHS). On older systems, the mail spool may be
8281 physically located in <file>/var/spool/mail</file>, but all
8282 access to the mail spool should be via the
8283 <file>/var/mail</file> symlink. The mail spool is part of the
8284 base system and not part of the MTA package.
8288 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8289 programs (such as IMAP daemons) must lock the mailbox in an
8290 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8291 be combined with dot locking. To avoid deadlocks, a program
8292 should use <tt>fcntl()</tt> first and dot locking after
8293 this, or alternatively implement the two locking methods in
8294 a non blocking way<footnote>
8295 If it is not possible to establish both locks, the
8296 system shouldn't wait for the second lock to be
8297 established, but remove the first lock, wait a (random)
8298 time, and start over locking again.
8299 </footnote>. Using the functions <tt>maillock</tt> and
8300 <tt>mailunlock</tt> provided by the
8301 <tt>liblockfile*</tt><footnote>
8302 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8303 to use these functions.
8304 </footnote> packages is the recommended way to realize this.
8308 Mailboxes are generally either mode 600 and owned by
8309 <var>user</var> or mode 660 and owned by
8310 <tt><var>user</var>:mail</tt><footnote>
8311 There are two traditional permission schemes for mail spools:
8312 mode 600 with all mail delivery done by processes running as
8313 the destination user, or mode 660 and owned by group mail with
8314 mail delivery done by a process running as a system user in
8315 group mail. Historically, Debian required mode 660 mail
8316 spools to enable the latter model, but that model has become
8317 increasingly uncommon and the principle of least privilege
8318 indicates that mail systems that use the first model should
8319 use permissions of 600. If delivery to programs is permitted,
8320 it's easier to keep the mail system secure if the delivery
8321 agent runs as the destination user. Debian Policy therefore
8322 permits either scheme.
8323 </footnote>. The local system administrator may choose a
8324 different permission scheme; packages should not make
8325 assumptions about the permission and ownership of mailboxes
8326 unless required (such as when creating a new mailbox). A MUA
8327 may remove a mailbox (unless it has nonstandard permissions) in
8328 which case the MTA or another MUA must recreate it if needed.
8332 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8333 be setgid mail to do the locking mentioned above (and
8334 must obviously avoid accessing other users' mailboxes
8335 using this privilege).</p>
8338 <file>/etc/aliases</file> is the source file for the system mail
8339 aliases (e.g., postmaster, usenet, etc.), it is the one
8340 which the sysadmin and <prgn>postinst</prgn> scripts may
8341 edit. After <file>/etc/aliases</file> is edited the program or
8342 human editing it must call <prgn>newaliases</prgn>. All MTA
8343 packages must come with a <prgn>newaliases</prgn> program,
8344 even if it does nothing, but older MTA packages did not do
8345 this so programs should not fail if <prgn>newaliases</prgn>
8346 cannot be found. Note that because of this, all MTA
8347 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8348 <tt>Replaces: mail-transport-agent</tt> control file
8353 The convention of writing <tt>forward to
8354 <var>address</var></tt> in the mailbox itself is not
8355 supported. Use a <tt>.forward</tt> file instead.</p>
8358 The <prgn>rmail</prgn> program used by UUCP
8359 for incoming mail should be <file>/usr/sbin/rmail</file>.
8360 Likewise, <prgn>rsmtp</prgn>, for receiving
8361 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8365 If your package needs to know what hostname to use on (for
8366 example) outgoing news and mail messages which are generated
8367 locally, you should use the file <file>/etc/mailname</file>. It
8368 will contain the portion after the username and <tt>@</tt>
8369 (at) sign for email addresses of users on the machine
8370 (followed by a newline).
8374 Such a package should check for the existence of this file
8375 when it is being configured. If it exists, it should be
8376 used without comment, although an MTA's configuration script
8377 may wish to prompt the user even if it finds that this file
8378 exists. If the file does not exist, the package should
8379 prompt the user for the value (preferably using
8380 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8381 as well as using it in the package's configuration. The
8382 prompt should make it clear that the name will not just be
8383 used by that package. For example, in this situation the
8384 <tt>inn</tt> package could say something like:
8385 <example compact="compact">
8386 Please enter the "mail name" of your system. This is the
8387 hostname portion of the address to be shown on outgoing
8388 news and mail messages. The default is
8389 <var>syshostname</var>, your system's host name. Mail
8390 name ["<var>syshostname</var>"]:
8392 where <var>syshostname</var> is the output of <tt>hostname
8398 <heading>News system configuration</heading>
8401 All the configuration files related to the NNTP (news)
8402 servers and clients should be located under
8403 <file>/etc/news</file>.</p>
8406 There are some configuration issues that apply to a number
8407 of news clients and server packages on the machine. These
8411 <tag><file>/etc/news/organization</file></tag>
8413 A string which should appear as the
8414 organization header for all messages posted
8415 by NNTP clients on the machine
8418 <tag><file>/etc/news/server</file></tag>
8420 Contains the FQDN of the upstream NNTP
8421 server, or localhost if the local machine is
8426 Other global files may be added as required for cross-package news
8433 <heading>Programs for the X Window System</heading>
8436 <heading>Providing X support and package priorities</heading>
8439 Programs that can be configured with support for the X
8440 Window System must be configured to do so and must declare
8441 any package dependencies necessary to satisfy their
8442 runtime requirements when using the X Window System. If
8443 such a package is of higher priority than the X packages
8444 on which it depends, it is required that either the
8445 X-specific components be split into a separate package, or
8446 that an alternative version of the package, which includes
8447 X support, be provided, or that the package's priority be
8453 <heading>Packages providing an X server</heading>
8456 Packages that provide an X server that, directly or
8457 indirectly, communicates with real input and display
8458 hardware should declare in their control data that they
8459 provide the virtual package <tt>xserver</tt>.<footnote>
8460 This implements current practice, and provides an
8461 actual policy for usage of the <tt>xserver</tt>
8462 virtual package which appears in the virtual packages
8463 list. In a nutshell, X servers that interface
8464 directly with the display and input hardware or via
8465 another subsystem (e.g., GGI) should provide
8466 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8467 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8473 <heading>Packages providing a terminal emulator</heading>
8476 Packages that provide a terminal emulator for the X Window
8477 System which meet the criteria listed below should declare
8478 in their control data that they provide the virtual
8479 package <tt>x-terminal-emulator</tt>. They should also
8480 register themselves as an alternative for
8481 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8486 To be an <tt>x-terminal-emulator</tt>, a program must:
8487 <list compact="compact">
8489 Be able to emulate a DEC VT100 terminal, or a
8490 compatible terminal.
8494 Support the command-line option <tt>-e
8495 <var>command</var></tt>, which creates a new
8496 terminal window<footnote>
8497 "New terminal window" does not necessarily mean
8498 a new top-level X window directly parented by
8499 the window manager; it could, if the terminal
8500 emulator application were so coded, be a new
8501 "view" in a multiple-document interface (MDI).
8503 and runs the specified <var>command</var>,
8504 interpreting the entirety of the rest of the command
8505 line as a command to pass straight to exec, in the
8506 manner that <tt>xterm</tt> does.
8510 Support the command-line option <tt>-T
8511 <var>title</var></tt>, which creates a new terminal
8512 window with the window title <var>title</var>.
8519 <heading>Packages providing a window manager</heading>
8522 Packages that provide a window manager should declare in
8523 their control data that they provide the virtual package
8524 <tt>x-window-manager</tt>. They should also register
8525 themselves as an alternative for
8526 <file>/usr/bin/x-window-manager</file>, with a priority
8527 calculated as follows:
8528 <list compact="compact">
8530 Start with a priority of 20.
8534 If the window manager supports the Debian menu
8535 system, add 20 points if this support is available
8536 in the package's default configuration (i.e., no
8537 configuration files belonging to the system or user
8538 have to be edited to activate the feature); if
8539 configuration files must be modified, add only 10
8545 If the window manager complies with <url
8546 id="http://www.freedesktop.org/Standards/wm-spec"
8547 name="The Window Manager Specification Project">,
8548 written by the <url id="http://www.freedesktop.org/"
8549 name="Free Desktop Group">, add 40 points.
8553 If the window manager permits the X session to be
8554 restarted using a <em>different</em> window manager
8555 (without killing the X server) in its default
8556 configuration, add 10 points; otherwise add none.
8563 <heading>Packages providing fonts</heading>
8566 Packages that provide fonts for the X Window
8568 For the purposes of Debian Policy, a "font for the X
8569 Window System" is one which is accessed via X protocol
8570 requests. Fonts for the Linux console, for PostScript
8571 renderer, or any other purpose, do not fit this
8572 definition. Any tool which makes such fonts available
8573 to the X Window System, however, must abide by this
8576 must do a number of things to ensure that they are both
8577 available without modification of the X or font server
8578 configuration, and that they do not corrupt files used by
8579 other font packages to register information about
8583 Fonts of any type supported by the X Window System
8584 must be in a separate binary package from any
8585 executables, libraries, or documentation (except
8586 that specific to the fonts shipped, such as their
8587 license information). If one or more of the fonts
8588 so packaged are necessary for proper operation of
8589 the package with which they are associated the font
8590 package may be Recommended; if the fonts merely
8591 provide an enhancement, a Suggests relationship may
8592 be used. Packages must not Depend on font
8594 This is because the X server may retrieve fonts
8595 from the local file system or over the network
8596 from an X font server; the Debian package system
8597 is empowered to deal only with the local
8603 BDF fonts must be converted to PCF fonts with the
8604 <prgn>bdftopcf</prgn> utility (available in the
8605 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8606 placed in a directory that corresponds to their
8608 <list compact="compact">
8610 100 dpi fonts must be placed in
8611 <file>/usr/share/fonts/X11/100dpi/</file>.
8615 75 dpi fonts must be placed in
8616 <file>/usr/share/fonts/X11/75dpi/</file>.
8620 Character-cell fonts, cursor fonts, and other
8621 low-resolution fonts must be placed in
8622 <file>/usr/share/fonts/X11/misc/</file>.
8628 Type 1 fonts must be placed in
8629 <file>/usr/share/fonts/X11/Type1/</file>. If font
8630 metric files are available, they must be placed here
8635 Subdirectories of <file>/usr/share/fonts/X11/</file>
8636 other than those listed above must be neither
8637 created nor used. (The <file>PEX</file>, <file>CID</file>,
8638 <file>Speedo</file>, and <file>cyrillic</file> directories
8639 are excepted for historical reasons, but installation of
8640 files into these directories remains discouraged.)
8644 Font packages may, instead of placing files directly
8645 in the X font directories listed above, provide
8646 symbolic links in that font directory pointing to
8647 the files' actual location in the filesystem. Such
8648 a location must comply with the FHS.
8652 Font packages should not contain both 75dpi and
8653 100dpi versions of a font. If both are available,
8654 they should be provided in separate binary packages
8655 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8656 the names of the packages containing the
8657 corresponding fonts.
8661 Fonts destined for the <file>misc</file> subdirectory
8662 should not be included in the same package as 75dpi
8663 or 100dpi fonts; instead, they should be provided in
8664 a separate package with <tt>-misc</tt> appended to
8669 Font packages must not provide the files
8670 <file>fonts.dir</file>, <file>fonts.alias</file>, or
8671 <file>fonts.scale</file> in a font directory:
8674 <file>fonts.dir</file> files must not be provided at all.
8678 <file>fonts.alias</file> and <file>fonts.scale</file>
8679 files, if needed, should be provided in the
8681 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
8682 where <var>fontdir</var> is the name of the
8684 <file>/usr/share/fonts/X11/</file> where the
8685 package's corresponding fonts are stored
8686 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
8687 <var>package</var> is the name of the package
8688 that provides these fonts, and
8689 <var>extension</var> is either <tt>scale</tt>
8690 or <tt>alias</tt>, whichever corresponds to
8697 Font packages must declare a dependency on
8698 <tt>xfonts-utils</tt> in their control
8703 Font packages that provide one or more
8704 <file>fonts.scale</file> files as described above must
8705 invoke <prgn>update-fonts-scale</prgn> on each
8706 directory into which they installed fonts
8707 <em>before</em> invoking
8708 <prgn>update-fonts-dir</prgn> on that directory.
8709 This invocation must occur in both the
8710 <prgn>postinst</prgn> (for all arguments) and
8711 <prgn>postrm</prgn> (for all arguments except
8712 <tt>upgrade</tt>) scripts.
8716 Font packages that provide one or more
8717 <file>fonts.alias</file> files as described above must
8718 invoke <prgn>update-fonts-alias</prgn> on each
8719 directory into which they installed fonts. This
8720 invocation must occur in both the
8721 <prgn>postinst</prgn> (for all arguments) and
8722 <prgn>postrm</prgn> (for all arguments except
8723 <tt>upgrade</tt>) scripts.
8727 Font packages must invoke
8728 <prgn>update-fonts-dir</prgn> on each directory into
8729 which they installed fonts. This invocation must
8730 occur in both the <prgn>postinst</prgn> (for all
8731 arguments) and <prgn>postrm</prgn> (for all
8732 arguments except <tt>upgrade</tt>) scripts.
8736 Font packages must not provide alias names for the
8737 fonts they include which collide with alias names
8738 already in use by fonts already packaged.
8742 Font packages must not provide fonts with the same
8743 XLFD registry name as another font already packaged.
8749 <sect1 id="appdefaults">
8750 <heading>Application defaults files</heading>
8753 Application defaults files must be installed in the
8754 directory <file>/etc/X11/app-defaults/</file> (use of a
8755 localized subdirectory of <file>/etc/X11/</file> as described
8756 in the <em>X Toolkit Intrinsics - C Language
8757 Interface</em> manual is also permitted). They must be
8758 registered as <tt>conffile</tt>s or handled as
8759 configuration files.
8763 Customization of programs' X resources may also be
8764 supported with the provision of a file with the same name
8765 as that of the package placed in
8766 the <file>/etc/X11/Xresources/</file> directory, which
8767 must be registered as a <tt>conffile</tt> or handled as a
8768 configuration file.<footnote>
8769 Note that this mechanism is not the same as using
8770 app-defaults; app-defaults are tied to the client
8771 binary on the local file system, whereas X resources
8772 are stored in the X server and affect all connecting
8779 <heading>Installation directory issues</heading>
8782 Historically, packages using the X Window System used a
8783 separate set of installation directories from other packages.
8784 This practice has been discontinued and packages using the X
8785 Window System should now generally be installed in the same
8786 directories as any other package. Specifically, packages must
8787 not install files under the <file>/usr/X11R6/</file> directory
8788 and the <file>/usr/X11R6/</file> directory hierarchy should be
8789 regarded as obsolete.
8793 Include files previously installed under
8794 <file>/usr/X11R6/include/X11/</file> should be installed into
8795 <file>/usr/include/X11/</file>. For files previously
8796 installed into subdirectories of
8797 <file>/usr/X11R6/lib/X11/</file>, package maintainers should
8798 determine if subdirectories of <file>/usr/lib/</file> and
8799 <file>/usr/share/</file> can be used. If not, a subdirectory
8800 of <file>/usr/lib/X11/</file> should be used.
8804 Configuration files for window, display, or session managers
8805 or other applications that are tightly integrated with the X
8806 Window System may be placed in a subdirectory
8807 of <file>/etc/X11/</file> corresponding to the package name.
8808 Other X Window System applications should use
8809 the <file>/etc/</file> directory unless otherwise mandated by
8810 policy (such as for <ref id="appdefaults">).
8815 <heading>The OSF/Motif and OpenMotif libraries</heading>
8818 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8819 OpenMotif libraries</em><footnote>
8820 OSF/Motif and OpenMotif are collectively referred to as
8821 "Motif" in this policy document.
8823 should be compiled against and tested with LessTif (a free
8824 re-implementation of Motif) instead. If the maintainer
8825 judges that the program or programs do not work
8826 sufficiently well with LessTif to be distributed and
8827 supported, but do so when compiled against Motif, then two
8828 versions of the package should be created; one linked
8829 statically against Motif and with <tt>-smotif</tt>
8830 appended to the package name, and one linked dynamically
8831 against Motif and with <tt>-dmotif</tt> appended to the
8836 Both Motif-linked versions are dependent
8837 upon non-DFSG-compliant software and thus cannot be
8838 uploaded to the <em>main</em> distribution; if the
8839 software is itself DFSG-compliant it may be uploaded to
8840 the <em>contrib</em> distribution. While known existing
8841 versions of Motif permit unlimited redistribution of
8842 binaries linked against the library (whether statically or
8843 dynamically), it is the package maintainer's
8844 responsibility to determine whether this is permitted by
8845 the license of the copy of Motif in their possession.
8851 <heading>Perl programs and modules</heading>
8854 Perl programs and modules should follow the current Perl policy.
8858 The Perl policy can be found in the <tt>perl-policy</tt>
8859 files in the <tt>debian-policy</tt> package.
8860 It is also available from the Debian web mirrors at
8861 <tt><url name="/doc/packaging-manuals/perl-policy/"
8862 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8867 <heading>Emacs lisp programs</heading>
8870 Please refer to the "Debian Emacs Policy" for details of how to
8871 package emacs lisp programs.
8875 The Emacs policy is available in
8876 <file>debian-emacs-policy.gz</file> of the
8877 <package>emacsen-common</package> package.
8878 It is also available from the Debian web mirrors at
8879 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8880 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8885 <heading>Games</heading>
8888 The permissions on <file>/var/games</file> are mode 755, owner
8889 <tt>root</tt> and group <tt>root</tt>.
8893 Each game decides on its own security policy.</p>
8896 Games which require protected, privileged access to
8897 high-score files, saved games, etc., may be made
8898 set-<em>group</em>-id (mode 2755) and owned by
8899 <tt>root:games</tt>, and use files and directories with
8900 appropriate permissions (770 <tt>root:games</tt>, for
8901 example). They must not be made
8902 set-<em>user</em>-id, as this causes security problems. (If
8903 an attacker can subvert any set-user-id game they can
8904 overwrite the executable of any other, causing other players
8905 of these games to run a Trojan horse program. With a
8906 set-group-id game the attacker only gets access to less
8907 important game data, and if they can get at the other
8908 players' accounts at all it will take considerably more
8912 Some packages, for example some fortune cookie programs, are
8913 configured by the upstream authors to install with their
8914 data files or other static information made unreadable so
8915 that they can only be accessed through set-id programs
8916 provided. You should not do this in a Debian package: anyone can
8917 download the <file>.deb</file> file and read the data from it,
8918 so there is no point making the files unreadable. Not
8919 making the files unreadable also means that you don't have
8920 to make so many programs set-id, which reduces the risk of a
8924 As described in the FHS, binaries of games should be
8925 installed in the directory <file>/usr/games</file>. This also
8926 applies to games that use the X Window System. Manual pages
8927 for games (X and non-X games) should be installed in
8928 <file>/usr/share/man/man6</file>.</p>
8934 <heading>Documentation</heading>
8937 <heading>Manual pages</heading>
8940 You should install manual pages in <prgn>nroff</prgn> source
8941 form, in appropriate places under <file>/usr/share/man</file>.
8942 You should only use sections 1 to 9 (see the FHS for more
8943 details). You must not install a pre-formatted "cat page".
8947 Each program, utility, and function should have an
8948 associated manual page included in the same package. It is
8949 suggested that all configuration files also have a manual
8950 page included as well. Manual pages for protocols and other
8951 auxiliary things are optional.
8955 If no manual page is available, this is considered as a bug
8956 and should be reported to the Debian Bug Tracking System (the
8957 maintainer of the package is allowed to write this bug report
8958 themselves, if they so desire). Do not close the bug report
8959 until a proper man page is available.<footnote>
8960 It is not very hard to write a man page. See the
8961 <url id="http://www.schweikhardt.net/man_page_howto.html"
8962 name="Man-Page-HOWTO">,
8963 <manref name="man" section="7">, the examples
8964 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8965 the helper program <prgn>help2man</prgn>, or the
8966 directory <file>/usr/share/doc/man-db/examples</file>.
8971 You may forward a complaint about a missing man page to the
8972 upstream authors, and mark the bug as forwarded in the
8973 Debian bug tracking system. Even though the GNU Project do
8974 not in general consider the lack of a man page to be a bug,
8975 we do; if they tell you that they don't consider it a bug
8976 you should leave the bug in our bug tracking system open
8981 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8985 If one man page needs to be accessible via several names it
8986 is better to use a symbolic link than the <file>.so</file>
8987 feature, but there is no need to fiddle with the relevant
8988 parts of the upstream source to change from <file>.so</file> to
8989 symlinks: don't do it unless it's easy. You should not
8990 create hard links in the manual page directories, nor put
8991 absolute filenames in <file>.so</file> directives. The filename
8992 in a <file>.so</file> in a man page should be relative to the
8993 base of the man page tree (usually
8994 <file>/usr/share/man</file>). If you do not create any links
8995 (whether symlinks, hard links, or <tt>.so</tt> directives)
8996 in the file system to the alternate names of the man page,
8997 then you should not rely on <prgn>man</prgn> finding your
8998 man page under those names based solely on the information in
8999 the man page's header.<footnote>
9000 Supporting this in <prgn>man</prgn> often requires
9001 unreasonable processing time to find a manual page or to
9002 report that none exists, and moves knowledge into man's
9003 database that would be better left in the file system.
9004 This support is therefore deprecated and will cease to
9005 be present in the future.
9010 Manual pages in locale-specific subdirectories of
9011 <file>/usr/share/man</file> should use either UTF-8 or the usual
9012 legacy encoding for that language (normally the one corresponding
9013 to the shortest relevant locale name in
9014 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
9015 <file>/usr/share/man/fr</file> should use either UTF-8 or
9016 ISO-8859-1.<footnote>
9017 <prgn>man</prgn> will automatically detect whether UTF-8 is in
9018 use. In future, all manual pages will be required to use
9024 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
9025 included in the subdirectory name unless it indicates a
9026 significant difference in the language, as this excludes
9027 speakers of the language in other countries.<footnote>
9028 At the time of writing, Chinese and Portuguese are the main
9029 languages with such differences, so <file>pt_BR</file>,
9030 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
9035 If a localized version of a manual page is provided, it should
9036 either be up-to-date or it should be obvious to the reader that
9037 it is outdated and the original manual page should be used
9038 instead. This can be done either by a note at the beginning of
9039 the manual page or by showing the missing or changed portions in
9040 the original language instead of the target language.
9045 <heading>Info documents</heading>
9048 Info documents should be installed in <file>/usr/share/info</file>.
9049 They should be compressed with <tt>gzip -9</tt>.
9053 The <prgn>install-info</prgn> program maintains a directory of
9054 installed info documents in <file>/usr/share/info/dir</file> for
9055 the use of info readers.<footnote>
9056 It was previously necessary for packages installing info
9057 documents to run <prgn>install-info</prgn> from maintainer
9058 scripts. This is no longer necessary. The installation
9059 system now uses dpkg triggers.
9061 This file must not be included in packages. Packages containing
9062 info documents should depend on <tt>dpkg (>= 1.15.4) |
9063 install-info</tt> to ensure that the directory file is properly
9064 rebuilt during partial upgrades from Debian 5.0 (lenny) and
9069 Info documents should contain section and directory entry
9070 information in the document for the use
9071 of <prgn>install-info</prgn>. The section should be specified
9072 via a line starting with <tt>INFO-DIR-SECTION</tt> followed by a
9073 space and the section of this info page. The directory entry or
9074 entries should be included between
9075 a <tt>START-INFO-DIR-ENTRY</tt> line and
9076 an <tt>END-INFO-DIR-ENTRY</tt> line. For example:
9078 INFO-DIR-SECTION Individual utilities
9079 START-INFO-DIR-ENTRY
9080 * example: (example). An example info directory entry.
9083 To determine which section to use, you should look
9084 at <file>/usr/share/info/dir</file> on your system and choose
9085 the most relevant (or create a new section if none of the
9086 current sections are relevant).<footnote>
9087 Normally, info documents are generated from Texinfo source.
9088 To include this information in the generated info document, if
9089 it is absent, add commands like:
9091 @dircategory Individual utilities
9093 * example: (example). An example info directory entry.
9096 to the Texinfo source of the document and ensure that the info
9097 documents are rebuilt from source during the package build.
9103 <heading>Additional documentation</heading>
9106 Any additional documentation that comes with the package may
9107 be installed at the discretion of the package maintainer.
9108 Plain text documentation should be installed in the directory
9109 <file>/usr/share/doc/<var>package</var></file>, where
9110 <var>package</var> is the name of the package, and
9111 compressed with <tt>gzip -9</tt> unless it is small.
9115 If a package comes with large amounts of documentation which
9116 many users of the package will not require you should create
9117 a separate binary package to contain it, so that it does not
9118 take up disk space on the machines of users who do not need
9119 or want it installed.</p>
9122 It is often a good idea to put text information files
9123 (<file>README</file>s, changelogs, and so forth) that come with
9124 the source package in <file>/usr/share/doc/<var>package</var></file>
9125 in the binary package. However, you don't need to install
9126 the instructions for building and installing the package, of
9130 Packages must not require the existence of any files in
9131 <file>/usr/share/doc/</file> in order to function
9133 The system administrator should be able to
9134 delete files in <file>/usr/share/doc/</file> without causing
9135 any programs to break.
9137 Any files that are referenced by programs but are also
9138 useful as stand alone documentation should be installed under
9139 <file>/usr/share/<var>package</var>/</file> with symbolic links from
9140 <file>/usr/share/doc/<var>package</var></file>.
9144 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9145 link to another directory in <file>/usr/share/doc</file> only if
9146 the two packages both come from the same source and the
9147 first package Depends on the second.<footnote>
9149 Please note that this does not override the section on
9150 changelog files below, so the file
9151 <file>/usr/share/doc/<var>package</var>/changelog.Debian.gz</file>
9152 must refer to the changelog for the current version of
9153 <var>package</var> in question. In practice, this means
9154 that the sources of the target and the destination of the
9155 symlink must be the same (same source package and
9162 Former Debian releases placed all additional documentation
9163 in <file>/usr/doc/<var>package</var></file>. This has been
9164 changed to <file>/usr/share/doc/<var>package</var></file>,
9165 and packages must not put documentation in the directory
9166 <file>/usr/doc/<var>package</var></file>. <footnote>
9167 At this phase of the transition, we no longer require a
9168 symbolic link in <file>/usr/doc/</file>. At a later point,
9169 policy shall change to make the symbolic links a bug.
9175 <heading>Preferred documentation formats</heading>
9178 The unification of Debian documentation is being carried out
9182 If your package comes with extensive documentation in a
9183 markup format that can be converted to various other formats
9184 you should if possible ship HTML versions in a binary
9185 package, in the directory
9186 <file>/usr/share/doc/<var>appropriate-package</var></file> or
9187 its subdirectories.<footnote>
9188 The rationale: The important thing here is that HTML
9189 docs should be available in <em>some</em> package, not
9190 necessarily in the main binary package.
9195 Other formats such as PostScript may be provided at the
9196 package maintainer's discretion.
9200 <sect id="copyrightfile">
9201 <heading>Copyright information</heading>
9204 Every package must be accompanied by a verbatim copy of its
9205 copyright information and distribution license in the file
9206 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
9207 file must neither be compressed nor be a symbolic link.
9211 In addition, the copyright file must say where the upstream
9212 sources (if any) were obtained. It should name the original
9213 authors of the package and the Debian maintainer(s) who were
9214 involved with its creation.
9218 Packages in the <em>contrib</em> or <em>non-free</em> archive
9219 areas should state in the copyright file that the package is not
9220 part of the Debian GNU/Linux distribution and briefly explain
9225 A copy of the file which will be installed in
9226 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9227 be in <file>debian/copyright</file> in the source package.
9231 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9232 link to another directory in <file>/usr/share/doc</file> only if
9233 the two packages both come from the same source and the
9234 first package Depends on the second. These rules are
9235 important because copyrights must be extractable by
9240 Packages distributed under the UCB BSD license, the Apache
9241 license (version 2.0), the Artistic license, the GNU GPL
9242 (version 2 or 3), the GNU LGPL (versions 2, 2.1, or 3), and the
9243 GNU FDL (versions 1.2 or 1.3) should refer to the corresponding
9244 files under <file>/usr/share/common-licenses</file>,<footnote>
9247 <file>/usr/share/common-licenses/BSD</file>,
9248 <file>/usr/share/common-licenses/Apache-2.0</file>,
9249 <file>/usr/share/common-licenses/Artistic</file>,
9250 <file>/usr/share/common-licenses/GPL-2</file>,
9251 <file>/usr/share/common-licenses/GPL-3</file>,
9252 <file>/usr/share/common-licenses/LGPL-2</file>,
9253 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9254 <file>/usr/share/common-licenses/LGPL-3</file>,
9255 <file>/usr/share/common-licenses/GFDL-1.2</file>, and
9256 <file>/usr/share/common-licenses/GFDL-1.3</file>
9259 </footnote> rather than quoting them in the copyright
9264 You should not use the copyright file as a general <file>README</file>
9265 file. If your package has such a file it should be
9266 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9267 <file>README.Debian</file> or some other appropriate place.</p>
9271 <heading>Examples</heading>
9274 Any examples (configurations, source files, whatever),
9275 should be installed in a directory
9276 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9277 files should not be referenced by any program: they're there
9278 for the benefit of the system administrator and users as
9279 documentation only. Architecture-specific example files
9280 should be installed in a directory
9281 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9283 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9284 latter directory itself may be a symbolic link to the
9289 If the purpose of a package is to provide examples, then the
9290 example files may be installed into
9291 <file>/usr/share/doc/<var>package</var></file>.
9295 <sect id="changelogs">
9296 <heading>Changelog files</heading>
9299 Packages that are not Debian-native must contain a
9300 compressed copy of the <file>debian/changelog</file> file from
9301 the Debian source tree in
9302 <file>/usr/share/doc/<var>package</var></file> with the name
9303 <file>changelog.Debian.gz</file>.
9307 If an upstream changelog is available, it should be accessible as
9308 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9309 plain text. If the upstream changelog is distributed in
9310 HTML, it should be made available in that form as
9311 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9312 and a plain text <file>changelog.gz</file> should be generated
9313 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9314 the upstream changelog files do not already conform to this
9315 naming convention, then this may be achieved either by
9316 renaming the files, or by adding a symbolic link, at the
9317 maintainer's discretion.<footnote>
9318 Rationale: People should not have to look in places for
9319 upstream changelogs merely because they are given
9320 different names or are distributed in HTML format.
9325 All of these files should be installed compressed using
9326 <tt>gzip -9</tt>, as they will become large with time even
9327 if they start out small.
9331 If the package has only one changelog which is used both as
9332 the Debian changelog and the upstream one because there is
9333 no separate upstream maintainer then that changelog should
9334 usually be installed as
9335 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9336 there is a separate upstream maintainer, but no upstream
9337 changelog, then the Debian changelog should still be called
9338 <file>changelog.Debian.gz</file>.
9342 For details about the format and contents of the Debian
9343 changelog file, please see <ref id="dpkgchangelog">.
9348 <appendix id="pkg-scope">
9349 <heading>Introduction and scope of these appendices</heading>
9352 These appendices are taken essentially verbatim from the
9353 now-deprecated Packaging Manual, version 3.2.1.0. They are
9354 the chapters which are likely to be of use to package
9355 maintainers and which have not already been included in the
9356 policy document itself. Most of these sections are very likely
9357 not relevant to policy; they should be treated as
9358 documentation for the packaging system. Please note that these
9359 appendices are included for convenience, and for historical
9360 reasons: they used to be part of policy package, and they have
9361 not yet been incorporated into dpkg documentation. However,
9362 they still have value, and hence they are presented here.
9366 They have not yet been checked to ensure that they are
9367 compatible with the contents of policy, and if there are any
9368 contradictions, the version in the main policy document takes
9369 precedence. The remaining chapters of the old Packaging
9370 Manual have also not been read in detail to ensure that there
9371 are not parts which have been left out. Both of these will be
9376 Certain parts of the Packaging manual were integrated into the
9377 Policy Manual proper, and removed from the appendices. Links
9378 have been placed from the old locations to the new ones.
9382 <prgn>dpkg</prgn> is a suite of programs for creating binary
9383 package files and installing and removing them on Unix
9385 <prgn>dpkg</prgn> is targeted primarily at Debian
9386 GNU/Linux, but may work on or be ported to other
9392 The binary packages are designed for the management of
9393 installed executable programs (usually compiled binaries) and
9394 their associated data, though source code examples and
9395 documentation are provided as part of some packages.</p>
9398 This manual describes the technical aspects of creating Debian
9399 binary packages (<file>.deb</file> files). It documents the
9400 behavior of the package management programs
9401 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9402 they interact with packages.</p>
9405 It also documents the interaction between
9406 <prgn>dselect</prgn>'s core and the access method scripts it
9407 uses to actually install the selected packages, and describes
9408 how to create a new access method.</p>
9411 This manual does not go into detail about the options and
9412 usage of the package building and installation tools. It
9413 should therefore be read in conjunction with those programs'
9418 The utility programs which are provided with <prgn>dpkg</prgn>
9419 for managing various system configuration and similar issues,
9420 such as <prgn>update-rc.d</prgn> and
9421 <prgn>install-info</prgn>, are not described in detail here -
9422 please see their man pages.
9426 It is assumed that the reader is reasonably familiar with the
9427 <prgn>dpkg</prgn> System Administrators' manual.
9428 Unfortunately this manual does not yet exist.
9432 The Debian version of the FSF's GNU hello program is provided
9433 as an example for people wishing to create Debian
9434 packages. The Debian <prgn>debmake</prgn> package is
9435 recommended as a very helpful tool in creating and maintaining
9436 Debian packages. However, while the tools and examples are
9437 helpful, they do not replace the need to read and follow the
9438 Policy and Programmer's Manual.</p>
9441 <appendix id="pkg-binarypkg">
9442 <heading>Binary packages (from old Packaging Manual)</heading>
9445 The binary package has two main sections. The first part
9446 consists of various control information files and scripts used
9447 by <prgn>dpkg</prgn> when installing and removing. See <ref
9448 id="pkg-controlarea">.
9452 The second part is an archive containing the files and
9453 directories to be installed.
9457 In the future binary packages may also contain other
9458 components, such as checksums and digital signatures. The
9459 format for the archive is described in full in the
9460 <file>deb(5)</file> man page.
9464 <sect id="pkg-bincreating"><heading>Creating package files -
9465 <prgn>dpkg-deb</prgn>
9469 All manipulation of binary package files is done by
9470 <prgn>dpkg-deb</prgn>; it's the only program that has
9471 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9472 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9473 will spot that the options requested are appropriate to
9474 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9479 In order to create a binary package you must make a
9480 directory tree which contains all the files and directories
9481 you want to have in the file system data part of the package.
9482 In Debian-format source packages this directory is usually
9483 <file>debian/tmp</file>, relative to the top of the package's
9488 They should have the locations (relative to the root of the
9489 directory tree you're constructing) ownerships and
9490 permissions which you want them to have on the system when
9495 With current versions of <prgn>dpkg</prgn> the uid/username
9496 and gid/groupname mappings for the users and groups being
9497 used should be the same on the system where the package is
9498 built and the one where it is installed.
9502 You need to add one special directory to the root of the
9503 miniature file system tree you're creating:
9504 <prgn>DEBIAN</prgn>. It should contain the control
9505 information files, notably the binary package control file
9506 (see <ref id="pkg-controlfile">).
9510 The <prgn>DEBIAN</prgn> directory will not appear in the
9511 file system archive of the package, and so won't be installed
9512 by <prgn>dpkg</prgn> when the package is unpacked.
9516 When you've prepared the package, you should invoke:
9518 dpkg --build <var>directory</var>
9523 This will build the package in
9524 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9525 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9526 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9531 See the man page <manref name="dpkg-deb" section="8"> for details of how
9532 to examine the contents of this newly-created file. You may find the
9533 output of following commands enlightening:
9535 dpkg-deb --info <var>filename</var>.deb
9536 dpkg-deb --contents <var>filename</var>.deb
9537 dpkg --contents <var>filename</var>.deb
9539 To view the copyright file for a package you could use this command:
9541 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
9546 <sect id="pkg-controlarea">
9547 <heading>Package control information files</heading>
9550 The control information portion of a binary package is a
9551 collection of files with names known to <prgn>dpkg</prgn>.
9552 It will treat the contents of these files specially - some
9553 of them contain information used by <prgn>dpkg</prgn> when
9554 installing or removing the package; others are scripts which
9555 the package maintainer wants <prgn>dpkg</prgn> to run.
9559 It is possible to put other files in the package control
9560 area, but this is not generally a good idea (though they
9561 will largely be ignored).
9565 Here is a brief list of the control info files supported by
9566 <prgn>dpkg</prgn> and a summary of what they're used for.
9571 <tag><tt>control</tt>
9574 This is the key description file used by
9575 <prgn>dpkg</prgn>. It specifies the package's name
9576 and version, gives its description for the user,
9577 states its relationships with other packages, and so
9578 forth. See <ref id="sourcecontrolfiles"> and
9579 <ref id="binarycontrolfiles">.
9583 It is usually generated automatically from information
9584 in the source package by the
9585 <prgn>dpkg-gencontrol</prgn> program, and with
9586 assistance from <prgn>dpkg-shlibdeps</prgn>.
9587 See <ref id="pkg-sourcetools">.
9591 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9596 These are executable files (usually scripts) which
9597 <prgn>dpkg</prgn> runs during installation, upgrade
9598 and removal of packages. They allow the package to
9599 deal with matters which are particular to that package
9600 or require more complicated processing than that
9601 provided by <prgn>dpkg</prgn>. Details of when and
9602 how they are called are in <ref id="maintainerscripts">.
9606 It is very important to make these scripts idempotent.
9607 See <ref id="idempotency">.
9611 The maintainer scripts are not guaranteed to run with a
9612 controlling terminal and may not be able to interact with
9613 the user. See <ref id="controllingterminal">.
9617 <tag><tt>conffiles</tt>
9620 This file contains a list of configuration files which
9621 are to be handled automatically by <prgn>dpkg</prgn>
9622 (see <ref id="pkg-conffiles">). Note that not necessarily
9623 every configuration file should be listed here.
9626 <tag><tt>shlibs</tt>
9629 This file contains a list of the shared libraries
9630 supplied by the package, with dependency details for
9631 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9632 when it determines what dependencies are required in a
9633 package control file. The <tt>shlibs</tt> file format
9634 is described on <ref id="shlibs">.
9639 <sect id="pkg-controlfile">
9640 <heading>The main control information file: <tt>control</tt></heading>
9643 The most important control information file used by
9644 <prgn>dpkg</prgn> when it installs a package is
9645 <tt>control</tt>. It contains all the package's "vital
9650 The binary package control files of packages built from
9651 Debian sources are made by a special tool,
9652 <prgn>dpkg-gencontrol</prgn>, which reads
9653 <file>debian/control</file> and <file>debian/changelog</file> to
9654 find the information it needs. See <ref id="pkg-sourcepkg"> for
9659 The fields in binary package control files are listed in
9660 <ref id="binarycontrolfiles">.
9664 A description of the syntax of control files and the purpose
9665 of the fields is available in <ref id="controlfields">.
9670 <heading>Time Stamps</heading>
9673 See <ref id="timestamps">.
9678 <appendix id="pkg-sourcepkg">
9679 <heading>Source packages (from old Packaging Manual) </heading>
9682 The Debian binary packages in the distribution are generated
9683 from Debian sources, which are in a special format to assist
9684 the easy and automatic building of binaries.
9687 <sect id="pkg-sourcetools">
9688 <heading>Tools for processing source packages</heading>
9691 Various tools are provided for manipulating source packages;
9692 they pack and unpack sources and help build of binary
9693 packages and help manage the distribution of new versions.
9697 They are introduced and typical uses described here; see
9698 <manref name="dpkg-source" section="1"> for full
9699 documentation about their arguments and operation.
9703 For examples of how to construct a Debian source package,
9704 and how to use those utilities that are used by Debian
9705 source packages, please see the <prgn>hello</prgn> example
9709 <sect1 id="pkg-dpkg-source">
9711 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
9716 This program is frequently used by hand, and is also
9717 called from package-independent automated building scripts
9718 such as <prgn>dpkg-buildpackage</prgn>.
9722 To unpack a package it is typically invoked with
9724 dpkg-source -x <var>.../path/to/filename</var>.dsc
9729 with the <file><var>filename</var>.tar.gz</file> and
9730 <file><var>filename</var>.diff.gz</file> (if applicable) in
9731 the same directory. It unpacks into
9732 <file><var>package</var>-<var>version</var></file>, and if
9734 <file><var>package</var>-<var>version</var>.orig</file>, in
9735 the current directory.
9739 To create a packed source archive it is typically invoked:
9741 dpkg-source -b <var>package</var>-<var>version</var>
9746 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
9747 <file>.diff.gz</file> (if appropriate) in the current
9748 directory. <prgn>dpkg-source</prgn> does not clean the
9749 source tree first - this must be done separately if it is
9754 See also <ref id="pkg-sourcearchives">.</p>
9758 <sect1 id="pkg-dpkg-buildpackage">
9760 <prgn>dpkg-buildpackage</prgn> - overall package-building
9765 <prgn>dpkg-buildpackage</prgn> is a script which invokes
9766 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
9767 targets <tt>clean</tt>, <tt>build</tt> and
9768 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
9769 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
9770 source and binary package upload.
9774 It is usually invoked by hand from the top level of the
9775 built or unbuilt source directory. It may be invoked with
9776 no arguments; useful arguments include:
9777 <taglist compact="compact">
9778 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
9781 Do not sign the <tt>.changes</tt> file or the
9782 source package <tt>.dsc</tt> file, respectively.</p>
9784 <tag><tt>-p<var>sign-command</var></tt></tag>
9787 Invoke <var>sign-command</var> instead of finding
9788 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
9789 <var>sign-command</var> must behave just like
9790 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9792 <tag><tt>-r<var>root-command</var></tt></tag>
9795 When root privilege is required, invoke the command
9796 <var>root-command</var>. <var>root-command</var>
9797 should invoke its first argument as a command, from
9798 the <prgn>PATH</prgn> if necessary, and pass its
9799 second and subsequent arguments to the command it
9800 calls. If no <var>root-command</var> is supplied
9801 then <var>dpkg-buildpackage</var> will take no
9802 special action to gain root privilege, so that for
9803 most packages it will have to be invoked as root to
9806 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9809 Two types of binary-only build and upload - see
9810 <manref name="dpkg-source" section="1">.
9817 <sect1 id="pkg-dpkg-gencontrol">
9819 <prgn>dpkg-gencontrol</prgn> - generates binary package
9824 This program is usually called from <file>debian/rules</file>
9825 (see <ref id="pkg-sourcetree">) in the top level of the source
9830 This is usually done just before the files and directories in the
9831 temporary directory tree where the package is being built have their
9832 permissions and ownerships set and the package is constructed using
9833 <prgn>dpkg-deb/</prgn>
9835 This is so that the control file which is produced has
9836 the right permissions
9841 <prgn>dpkg-gencontrol</prgn> must be called after all the
9842 files which are to go into the package have been placed in
9843 the temporary build directory, so that its calculation of
9844 the installed size of a package is correct.
9848 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9849 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9850 variable substitutions created by
9851 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9856 For a package which generates only one binary package, and
9857 which builds it in <file>debian/tmp</file> relative to the top
9858 of the source package, it is usually sufficient to call
9859 <prgn>dpkg-gencontrol</prgn>.
9863 Sources which build several binaries will typically need
9866 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9867 </example> The <tt>-P</tt> tells
9868 <prgn>dpkg-gencontrol</prgn> that the package is being
9869 built in a non-default directory, and the <tt>-p</tt>
9870 tells it which package's control file should be generated.
9874 <prgn>dpkg-gencontrol</prgn> also adds information to the
9875 list of files in <file>debian/files</file>, for the benefit of
9876 (for example) a future invocation of
9877 <prgn>dpkg-genchanges</prgn>.</p>
9880 <sect1 id="pkg-dpkg-shlibdeps">
9882 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9887 This program is usually called from <file>debian/rules</file>
9888 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9889 id="pkg-sourcetree">), in the top level of the source tree.
9893 Its arguments are executables and shared libraries
9896 They may be specified either in the locations in the
9897 source tree where they are created or in the locations
9898 in the temporary build tree where they are installed
9899 prior to binary package creation.
9901 </footnote> for which shared library dependencies should
9902 be included in the binary package's control file.
9906 If some of the found shared libraries should only
9907 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9908 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9909 by using the <tt>-d<var>dependency-field</var></tt> option
9910 before those executable(s). (Each <tt>-d</tt> option
9911 takes effect until the next <tt>-d</tt>.)
9915 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9916 output control file to be modified. Instead by default it
9917 adds to the <file>debian/substvars</file> file variable
9918 settings like <tt>shlibs:Depends</tt>. These variable
9919 settings must be referenced in dependency fields in the
9920 appropriate per-binary-package sections of the source
9925 For example, a package that generates an essential part
9926 which requires dependencies, and optional parts that
9927 which only require a recommendation, would separate those
9928 two sets of dependencies into two different fields.<footnote>
9929 At the time of writing, an example for this was the
9930 <package/xmms/ package, with Depends used for the xmms
9931 executable, Recommends for the plug-ins and Suggests for
9932 even more optional features provided by unzip.
9934 It can say in its <file>debian/rules</file>:
9936 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9937 -dRecommends <var>optionalpart anotheroptionalpart</var>
9939 and then in its main control file <file>debian/control</file>:
9942 Depends: ${shlibs:Depends}
9943 Recommends: ${shlibs:Recommends}
9949 Sources which produce several binary packages with
9950 different shared library dependency requirements can use
9951 the <tt>-p<var>varnameprefix</var></tt> option to override
9952 the default <tt>shlibs:</tt> prefix (one invocation of
9953 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9954 They can thus produce several sets of dependency
9955 variables, each of the form
9956 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9957 which can be referred to in the appropriate parts of the
9958 binary package control files.
9963 <sect1 id="pkg-dpkg-distaddfile">
9965 <prgn>dpkg-distaddfile</prgn> - adds a file to
9966 <file>debian/files</file>
9970 Some packages' uploads need to include files other than
9971 the source and binary package files.
9975 <prgn>dpkg-distaddfile</prgn> adds a file to the
9976 <file>debian/files</file> file so that it will be included in
9977 the <file>.changes</file> file when
9978 <prgn>dpkg-genchanges</prgn> is run.
9982 It is usually invoked from the <tt>binary</tt> target of
9983 <file>debian/rules</file>:
9985 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9987 The <var>filename</var> is relative to the directory where
9988 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9989 is usually the directory above the top level of the source
9990 tree. The <file>debian/rules</file> target should put the
9991 file there just before or just after calling
9992 <prgn>dpkg-distaddfile</prgn>.
9996 The <var>section</var> and <var>priority</var> are passed
9997 unchanged into the resulting <file>.changes</file> file.
10002 <sect1 id="pkg-dpkg-genchanges">
10004 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
10005 upload control file
10009 This program is usually called by package-independent
10010 automatic building scripts such as
10011 <prgn>dpkg-buildpackage</prgn>, but it may also be called
10016 It is usually called in the top level of a built source
10017 tree, and when invoked with no arguments will print out a
10018 straightforward <file>.changes</file> file based on the
10019 information in the source package's changelog and control
10020 file and the binary and source packages which should have
10026 <sect1 id="pkg-dpkg-parsechangelog">
10028 <prgn>dpkg-parsechangelog</prgn> - produces parsed
10029 representation of a changelog
10033 This program is used internally by
10034 <prgn>dpkg-source</prgn> et al. It may also occasionally
10035 be useful in <file>debian/rules</file> and elsewhere. It
10036 parses a changelog, <file>debian/changelog</file> by default,
10037 and prints a control-file format representation of the
10038 information in it to standard output.
10042 <sect1 id="pkg-dpkg-architecture">
10044 <prgn>dpkg-architecture</prgn> - information about the build and
10049 This program can be used manually, but is also invoked by
10050 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
10051 environment or make variables which specify the build and host
10052 architecture for the package building process.
10057 <sect id="pkg-sourcetree">
10058 <heading>The Debianised source tree</heading>
10061 The source archive scheme described later is intended to
10062 allow a Debianised source tree with some associated control
10063 information to be reproduced and transported easily. The
10064 Debianised source tree is a version of the original program
10065 with certain files added for the benefit of the
10066 Debianisation process, and with any other changes required
10067 made to the rest of the source code and installation
10072 The extra files created for Debian are in the subdirectory
10073 <file>debian</file> of the top level of the Debianised source
10074 tree. They are described below.
10077 <sect1 id="pkg-debianrules">
10078 <heading><file>debian/rules</file> - the main building script</heading>
10081 See <ref id="debianrules">.
10085 <sect1 id="pkg-srcsubstvars">
10086 <heading><file>debian/substvars</file> and variable substitutions</heading>
10089 See <ref id="substvars">.
10095 <heading><file>debian/files</file></heading>
10098 See <ref id="debianfiles">.
10102 <sect1><heading><file>debian/tmp</file>
10106 This is the canonical temporary location for the
10107 construction of binary packages by the <tt>binary</tt>
10108 target. The directory <file>tmp</file> serves as the root of
10109 the file system tree as it is being constructed (for
10110 example, by using the package's upstream makefiles install
10111 targets and redirecting the output there), and it also
10112 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10113 id="pkg-bincreating">.
10117 If several binary packages are generated from the same
10118 source tree it is usual to use several
10119 <file>debian/tmp<var>something</var></file> directories, for
10120 example <file>tmp-a</file> or <file>tmp-doc</file>.
10124 Whatever <file>tmp</file> directories are created and used by
10125 <tt>binary</tt> must of course be removed by the
10126 <tt>clean</tt> target.</p></sect1>
10130 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10134 As it exists on the FTP site, a Debian source package
10135 consists of three related files. You must have the right
10136 versions of all three to be able to use them.
10141 <tag>Debian source control file - <tt>.dsc</tt></tag>
10143 This file is a control file used by <prgn>dpkg-source</prgn>
10144 to extract a source package.
10145 See <ref id="debiansourcecontrolfiles">.
10149 Original source archive -
10151 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10157 This is a compressed (with <tt>gzip -9</tt>)
10158 <prgn>tar</prgn> file containing the source code from
10159 the upstream authors of the program.
10164 Debianisation diff -
10166 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10172 This is a unified context diff (<tt>diff -u</tt>)
10173 giving the changes which are required to turn the
10174 original source into the Debian source. These changes
10175 may only include editing and creating plain files.
10176 The permissions of files, the targets of symbolic
10177 links and the characteristics of special files or
10178 pipes may not be changed and no files may be removed
10183 All the directories in the diff must exist, except the
10184 <file>debian</file> subdirectory of the top of the source
10185 tree, which will be created by
10186 <prgn>dpkg-source</prgn> if necessary when unpacking.
10190 The <prgn>dpkg-source</prgn> program will
10191 automatically make the <file>debian/rules</file> file
10192 executable (see below).</p></item>
10197 If there is no original source code - for example, if the
10198 package is specially prepared for Debian or the Debian
10199 maintainer is the same as the upstream maintainer - the
10200 format is slightly different: then there is no diff, and the
10202 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10203 and preferably contains a directory named
10204 <file><var>package</var>-<var>version</var></file>.
10209 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10212 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10213 Debian source package. However, if it is not available it
10214 is possible to unpack a Debian source archive as follows:
10215 <enumlist compact="compact">
10218 Untar the tarfile, which will create a <file>.orig</file>
10222 <p>Rename the <file>.orig</file> directory to
10223 <file><var>package</var>-<var>version</var></file>.</p>
10227 Create the subdirectory <file>debian</file> at the top of
10228 the source tree.</p>
10230 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10232 <item><p>Untar the tarfile again if you want a copy of the original
10233 source code alongside the Debianised version.</p>
10238 It is not possible to generate a valid Debian source archive
10239 without using <prgn>dpkg-source</prgn>. In particular,
10240 attempting to use <prgn>diff</prgn> directly to generate the
10241 <file>.diff.gz</file> file will not work.
10245 <heading>Restrictions on objects in source packages</heading>
10248 The source package may not contain any hard links
10250 This is not currently detected when building source
10251 packages, but only when extracting
10255 Hard links may be permitted at some point in the
10256 future, but would require a fair amount of
10258 </footnote>, device special files, sockets or setuid or
10261 Setgid directories are allowed.
10266 The source packaging tools manage the changes between the
10267 original and Debianised source using <prgn>diff</prgn> and
10268 <prgn>patch</prgn>. Turning the original source tree as
10269 included in the <file>.orig.tar.gz</file> into the debianised
10270 source must not involve any changes which cannot be
10271 handled by these tools. Problematic changes which cause
10272 <prgn>dpkg-source</prgn> to halt with an error when
10273 building the source package are:
10274 <list compact="compact">
10275 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10277 <item><p>Changing the targets of symbolic links.</p>
10279 <item><p>Creating directories, other than <file>debian</file>.</p>
10281 <item><p>Changes to the contents of binary files.</p></item>
10282 </list> Changes which cause <prgn>dpkg-source</prgn> to
10283 print a warning but continue anyway are:
10284 <list compact="compact">
10287 Removing files, directories or symlinks.
10289 Renaming a file is not treated specially - it is
10290 seen as the removal of the old file (which
10291 generates a warning, but is otherwise ignored),
10292 and the creation of the new one.
10298 Changed text files which are missing the usual final
10299 newline (either in the original or the modified
10304 Changes which are not represented, but which are not detected by
10305 <prgn>dpkg-source</prgn>, are:
10306 <list compact="compact">
10307 <item><p>Changing the permissions of files (other than
10308 <file>debian/rules</file>) and directories.</p></item>
10313 The <file>debian</file> directory and <file>debian/rules</file>
10314 are handled specially by <prgn>dpkg-source</prgn> - before
10315 applying the changes it will create the <file>debian</file>
10316 directory, and afterwards it will make
10317 <file>debian/rules</file> world-executable.
10323 <appendix id="pkg-controlfields">
10324 <heading>Control files and their fields (from old Packaging Manual)</heading>
10327 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10328 data in a common format, known as control files. Binary and
10329 source packages have control data as do the <file>.changes</file>
10330 files which control the installation of uploaded files, and
10331 <prgn>dpkg</prgn>'s internal databases are in a similar
10336 <heading>Syntax of control files</heading>
10339 See <ref id="controlsyntax">.
10343 It is important to note that there are several fields which
10344 are optional as far as <prgn>dpkg</prgn> and the related
10345 tools are concerned, but which must appear in every Debian
10346 package, or whose omission may cause problems.
10351 <heading>List of fields</heading>
10354 See <ref id="controlfieldslist">.
10358 This section now contains only the fields that didn't belong
10359 to the Policy manual.
10362 <sect1 id="pkg-f-Filename">
10363 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10366 These fields in <tt>Packages</tt> files give the
10367 filename(s) of (the parts of) a package in the
10368 distribution directories, relative to the root of the
10369 Debian hierarchy. If the package has been split into
10370 several parts the parts are all listed in order, separated
10375 <sect1 id="pkg-f-Size">
10376 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10379 These fields in <file>Packages</file> files give the size (in
10380 bytes, expressed in decimal) and MD5 checksum of the
10381 file(s) which make(s) up a binary package in the
10382 distribution. If the package is split into several parts
10383 the values for the parts are listed in order, separated by
10388 <sect1 id="pkg-f-Status">
10389 <heading><tt>Status</tt></heading>
10392 This field in <prgn>dpkg</prgn>'s status file records
10393 whether the user wants a package installed, removed or
10394 left alone, whether it is broken (requiring
10395 re-installation) or not and what its current state on the
10396 system is. Each of these pieces of information is a
10401 <sect1 id="pkg-f-Config-Version">
10402 <heading><tt>Config-Version</tt></heading>
10405 If a package is not installed or not configured, this
10406 field in <prgn>dpkg</prgn>'s status file records the last
10407 version of the package which was successfully
10412 <sect1 id="pkg-f-Conffiles">
10413 <heading><tt>Conffiles</tt></heading>
10416 This field in <prgn>dpkg</prgn>'s status file contains
10417 information about the automatically-managed configuration
10418 files held by a package. This field should <em>not</em>
10419 appear anywhere in a package!
10424 <heading>Obsolete fields</heading>
10427 These are still recognized by <prgn>dpkg</prgn> but should
10428 not appear anywhere any more.
10430 <taglist compact="compact">
10432 <tag><tt>Revision</tt></tag>
10433 <tag><tt>Package-Revision</tt></tag>
10434 <tag><tt>Package_Revision</tt></tag>
10436 The Debian revision part of the package version was
10437 at one point in a separate control file field. This
10438 field went through several names.
10441 <tag><tt>Recommended</tt></tag>
10442 <item>Old name for <tt>Recommends</tt>.</item>
10444 <tag><tt>Optional</tt></tag>
10445 <item>Old name for <tt>Suggests</tt>.</item>
10447 <tag><tt>Class</tt></tag>
10448 <item>Old name for <tt>Priority</tt>.</item>
10457 <appendix id="pkg-conffiles">
10458 <heading>Configuration file handling (from old Packaging Manual)</heading>
10461 <prgn>dpkg</prgn> can do a certain amount of automatic
10462 handling of package configuration files.
10466 Whether this mechanism is appropriate depends on a number of
10467 factors, but basically there are two approaches to any
10468 particular configuration file.
10472 The easy method is to ship a best-effort configuration in the
10473 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10474 handle updates. If the user is unlikely to want to edit the
10475 file, but you need them to be able to without losing their
10476 changes, and a new package with a changed version of the file
10477 is only released infrequently, this is a good approach.
10481 The hard method is to build the configuration file from
10482 scratch in the <prgn>postinst</prgn> script, and to take the
10483 responsibility for fixing any mistakes made in earlier
10484 versions of the package automatically. This will be
10485 appropriate if the file is likely to need to be different on
10489 <sect><heading>Automatic handling of configuration files by
10494 A package may contain a control area file called
10495 <tt>conffiles</tt>. This file should be a list of filenames
10496 of configuration files needing automatic handling, separated
10497 by newlines. The filenames should be absolute pathnames,
10498 and the files referred to should actually exist in the
10503 When a package is upgraded <prgn>dpkg</prgn> will process
10504 the configuration files during the configuration stage,
10505 shortly before it runs the package's <prgn>postinst</prgn>
10510 For each file it checks to see whether the version of the
10511 file included in the package is the same as the one that was
10512 included in the last version of the package (the one that is
10513 being upgraded from); it also compares the version currently
10514 installed on the system with the one shipped with the last
10519 If neither the user nor the package maintainer has changed
10520 the file, it is left alone. If one or the other has changed
10521 their version, then the changed version is preferred - i.e.,
10522 if the user edits their file, but the package maintainer
10523 doesn't ship a different version, the user's changes will
10524 stay, silently, but if the maintainer ships a new version
10525 and the user hasn't edited it the new version will be
10526 installed (with an informative message). If both have
10527 changed their version the user is prompted about the problem
10528 and must resolve the differences themselves.
10532 The comparisons are done by calculating the MD5 message
10533 digests of the files, and storing the MD5 of the file as it
10534 was included in the most recent version of the package.
10538 When a package is installed for the first time
10539 <prgn>dpkg</prgn> will install the file that comes with it,
10540 unless that would mean overwriting a file already on the
10545 However, note that <prgn>dpkg</prgn> will <em>not</em>
10546 replace a conffile that was removed by the user (or by a
10547 script). This is necessary because with some programs a
10548 missing file produces an effect hard or impossible to
10549 achieve in another way, so that a missing file needs to be
10550 kept that way if the user did it.
10554 Note that a package should <em>not</em> modify a
10555 <prgn>dpkg</prgn>-handled conffile in its maintainer
10556 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10557 the user confusing and possibly dangerous options for
10558 conffile update when the package is upgraded.</p>
10561 <sect><heading>Fully-featured maintainer script configuration
10566 For files which contain site-specific information such as
10567 the hostname and networking details and so forth, it is
10568 better to create the file in the package's
10569 <prgn>postinst</prgn> script.
10573 This will typically involve examining the state of the rest
10574 of the system to determine values and other information, and
10575 may involve prompting the user for some information which
10576 can't be obtained some other way.
10580 When using this method there are a couple of important
10581 issues which should be considered:
10585 If you discover a bug in the program which generates the
10586 configuration file, or if the format of the file changes
10587 from one version to the next, you will have to arrange for
10588 the postinst script to do something sensible - usually this
10589 will mean editing the installed configuration file to remove
10590 the problem or change the syntax. You will have to do this
10591 very carefully, since the user may have changed the file,
10592 perhaps to fix the very problem that your script is trying
10593 to deal with - you will have to detect these situations and
10594 deal with them correctly.
10598 If you do go down this route it's probably a good idea to
10599 make the program that generates the configuration file(s) a
10600 separate program in <file>/usr/sbin</file>, by convention called
10601 <file><var>package</var>config</file> and then run that if
10602 appropriate from the post-installation script. The
10603 <tt><var>package</var>config</tt> program should not
10604 unquestioningly overwrite an existing configuration - if its
10605 mode of operation is geared towards setting up a package for
10606 the first time (rather than any arbitrary reconfiguration
10607 later) you should have it check whether the configuration
10608 already exists, and require a <tt>--force</tt> flag to
10609 overwrite it.</p></sect>
10612 <appendix id="pkg-alternatives"><heading>Alternative versions of
10613 an interface - <prgn>update-alternatives</prgn> (from old
10618 When several packages all provide different versions of the
10619 same program or file it is useful to have the system select a
10620 default, but to allow the system administrator to change it
10621 and have their decisions respected.
10625 For example, there are several versions of the <prgn>vi</prgn>
10626 editor, and there is no reason to prevent all of them from
10627 being installed at once, each under their own name
10628 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10629 Nevertheless it is desirable to have the name <tt>vi</tt>
10630 refer to something, at least by default.
10634 If all the packages involved cooperate, this can be done with
10635 <prgn>update-alternatives</prgn>.
10639 Each package provides its own version under its own name, and
10640 calls <prgn>update-alternatives</prgn> in its postinst to
10641 register its version (and again in its prerm to deregister
10646 See the man page <manref name="update-alternatives"
10647 section="8"> for details.
10651 If <prgn>update-alternatives</prgn> does not seem appropriate
10652 you may wish to consider using diversions instead.</p>
10655 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10656 package's version of a file (from old Packaging Manual)
10660 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10661 when it reinstalls the package it belongs to, and to have it
10662 put the file from the package somewhere else instead.
10666 This can be used locally to override a package's version of a
10667 file, or by one package to override another's version (or
10668 provide a wrapper for it).
10672 Before deciding to use a diversion, read <ref
10673 id="pkg-alternatives"> to see if you really want a diversion
10674 rather than several alternative versions of a program.
10678 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10679 and updated by a special program <prgn>dpkg-divert</prgn>.
10680 Please see <manref name="dpkg-divert" section="8"> for full
10681 details of its operation.
10685 When a package wishes to divert a file from another, it should
10686 call <prgn>dpkg-divert</prgn> in its preinst to add the
10687 diversion and rename the existing file. For example,
10688 supposing that a <prgn>smailwrapper</prgn> package wishes to
10689 install a wrapper around <file>/usr/sbin/smail</file>:
10691 dpkg-divert --package smailwrapper --add --rename \
10692 --divert /usr/sbin/smail.real /usr/sbin/smail
10693 </example> The <tt>--package smailwrapper</tt> ensures that
10694 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
10695 can bypass the diversion and get installed as the true version.
10696 It's safe to add the diversion unconditionally on upgrades since
10697 it will be left unchanged if it already exists, but
10698 <prgn>dpkg-divert</prgn> will display a message. To suppress that
10699 message, make the command conditional on the version from which
10700 the package is being upgraded:
10702 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
10703 dpkg-divert --package smailwrapper --add --rename \
10704 --divert /usr/sbin/smail.real /usr/sbin/smail
10706 </example> where <tt>1.0-2</tt> is the version at which the
10707 diversion was first added to the package. Running the command
10708 during abort-upgrade is pointless but harmless.
10712 The postrm has to do the reverse:
10714 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
10715 dpkg-divert --package smailwrapper --remove --rename \
10716 --divert /usr/sbin/smail.real /usr/sbin/smail
10718 </example> If the diversion was added at a particular version, the
10719 postrm should also handle the failure case of upgrading from an
10720 older version (unless the older version is so old that direct
10721 upgrades are no longer supported):
10723 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
10724 dpkg-divert --package smailwrapper --remove --rename \
10725 --divert /usr/sbin/smail.real /usr/sbin/smail
10727 </example> where <tt>1.02-2</tt> is the version at which the
10728 diversion was first added to the package. The postrm should not
10729 remove the diversion on upgrades both because there's no reason to
10730 remove the diversion only to immediately re-add it and since the
10731 postrm of the old package is run after unpacking so the removal of
10732 the diversion will fail.
10736 Do not attempt to divert a file which is vitally important for
10737 the system's operation - when using <prgn>dpkg-divert</prgn>
10738 there is a time, after it has been diverted but before
10739 <prgn>dpkg</prgn> has installed the new version, when the file
10740 does not exist.</p>
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