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10 <title>Debian Policy Manual</title>
11 <author><qref id="authors">The Debian Policy Mailing List</qref></author>
12 <version>version &version;, &date;</version>
15 This manual describes the policy requirements for the Debian
16 GNU/Linux distribution. This includes the structure and
17 contents of the Debian archive and several design issues of
18 the operating system, as well as technical requirements that
19 each package must satisfy to be included in the distribution.
24 Copyright © 1996,1997,1998 Ian Jackson
25 and Christian Schwarz.
28 These are the copyright dates of the original Policy manual.
29 Since then, this manual has been updated by many others. No
30 comprehensive collection of copyright notices for subsequent
35 This manual is free software; you may redistribute it and/or
36 modify it under the terms of the GNU General Public License
37 as published by the Free Software Foundation; either version
38 2, or (at your option) any later version.
42 This is distributed in the hope that it will be useful, but
43 <em>without any warranty</em>; without even the implied
44 warranty of merchantability or fitness for a particular
45 purpose. See the GNU General Public License for more
50 A copy of the GNU General Public License is available as
51 <file>/usr/share/common-licenses/GPL</file> in the Debian GNU/Linux
52 distribution or on the World Wide Web at
53 <url id="http://www.gnu.org/copyleft/gpl.html"
54 name="the GNU General Public Licence">. You can also
55 obtain it by writing to the Free Software Foundation, Inc.,
56 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
64 <heading>About this manual</heading>
66 <heading>Scope</heading>
68 This manual describes the policy requirements for the Debian
69 GNU/Linux distribution. This includes the structure and
70 contents of the Debian archive and several design issues of the
71 operating system, as well as technical requirements that
72 each package must satisfy to be included in the
77 This manual also describes Debian policy as it relates to
78 creating Debian packages. It is not a tutorial on how to build
79 packages, nor is it exhaustive where it comes to describing
80 the behavior of the packaging system. Instead, this manual
81 attempts to define the interface to the package management
82 system that the developers have to be conversant with.<footnote>
83 Informally, the criteria used for inclusion is that the
84 material meet one of the following requirements:
85 <taglist compact="compact">
86 <tag>Standard interfaces</tag>
88 The material presented represents an interface to
89 the packaging system that is mandated for use, and
90 is used by, a significant number of packages, and
91 therefore should not be changed without peer
92 review. Package maintainers can then rely on this
93 interface not changing, and the package management
94 software authors need to ensure compatibility with
95 this interface definition. (Control file and
96 changelog file formats are examples.)
98 <tag>Chosen Convention</tag>
100 If there are a number of technically viable choices
101 that can be made, but one needs to select one of
102 these options for inter-operability. The version
103 number format is one example.
106 Please note that these are not mutually exclusive;
107 selected conventions often become parts of standard
113 The footnotes present in this manual are
114 merely informative, and are not part of Debian policy itself.
118 The appendices to this manual are not necessarily normative,
119 either. Please see <ref id="pkg-scope"> for more information.
123 In the normative part of this manual,
124 the words <em>must</em>, <em>should</em> and
125 <em>may</em>, and the adjectives <em>required</em>,
126 <em>recommended</em> and <em>optional</em>, are used to
127 distinguish the significance of the various guidelines in
128 this policy document. Packages that do not conform to the
129 guidelines denoted by <em>must</em> (or <em>required</em>)
130 will generally not be considered acceptable for the Debian
131 distribution. Non-conformance with guidelines denoted by
132 <em>should</em> (or <em>recommended</em>) will generally be
133 considered a bug, but will not necessarily render a package
134 unsuitable for distribution. Guidelines denoted by
135 <em>may</em> (or <em>optional</em>) are truly optional and
136 adherence is left to the maintainer's discretion.
140 These classifications are roughly equivalent to the bug
141 severities <em>serious</em> (for <em>must</em> or
142 <em>required</em> directive violations), <em>minor</em>,
143 <em>normal</em> or <em>important</em>
144 (for <em>should</em> or <em>recommended</em> directive
145 violations) and <em>wishlist</em> (for <em>optional</em>
148 Compare RFC 2119. Note, however, that these words are
149 used in a different way in this document.
154 Much of the information presented in this manual will be
155 useful even when building a package which is to be
156 distributed in some other way or is intended for local use
162 <heading>New versions of this document</heading>
165 This manual is distributed via the Debian package
166 <package><url name="debian-policy"
167 id="http://packages.debian.org/debian-policy"></package>
168 (<httpsite>packages.debian.org</httpsite>
169 <httppath>/debian-policy</httppath>).
173 The current version of this document is also available from
174 the Debian web mirrors at
175 <tt><url name="/doc/debian-policy/"
176 id="http://www.debian.org/doc/debian-policy/"></tt>.
178 <httpsite>www.debian.org</httpsite>
179 <httppath>/doc/debian-policy/</httppath>)
180 Also available from the same directory are several other
181 formats: <file>policy.html.tar.gz</file>
182 (<httppath>/doc/debian-policy/policy.html.tar.gz</httppath>),
183 <file>policy.pdf.gz</file>
184 (<httppath>/doc/debian-policy/policy.pdf.gz</httppath>)
185 and <file>policy.ps.gz</file>
186 (<httppath>/doc/debian-policy/policy.ps.gz</httppath>).
190 The <package>debian-policy</package> package also includes the file
191 <file>upgrading-checklist.txt.gz</file> which indicates policy
192 changes between versions of this document.
197 <heading>Authors and Maintainers</heading>
200 Originally called "Debian GNU/Linux Policy Manual", this
201 manual was initially written in 1996 by Ian Jackson.
202 It was revised on November 27th, 1996 by David A. Morris.
203 Christian Schwarz added new sections on March 15th, 1997,
204 and reworked/restructured it in April-July 1997.
205 Christoph Lameter contributed the "Web Standard".
206 Julian Gilbey largely restructured it in 2001.
210 Since September 1998, the responsibility for the contents of
211 this document lies on the <url name="debian-policy mailing list"
212 id="mailto:debian-policy@lists.debian.org">. Proposals
213 are discussed there and inserted into policy after a certain
214 consensus is established.
215 <!-- insert shameless policy-process plug here eventually -->
216 The actual editing is done by a group of maintainers that have
217 no editorial powers. These are the current maintainers:
220 <item>Julian Gilbey</item>
221 <item>Branden Robinson</item>
222 <item>Josip Rodin</item>
223 <item>Manoj Srivastava</item>
228 While the authors of this document have tried hard to avoid
229 typos and other errors, these do still occur. If you discover
230 an error in this manual or if you want to give any
231 comments, suggestions, or criticisms please send an email to
232 the Debian Policy List,
233 <email>debian-policy@lists.debian.org</email>, or submit a
234 bug report against the <tt>debian-policy</tt> package.
238 Please do not try to reach the individual authors or maintainers
239 of the Policy Manual regarding changes to the Policy.
244 <heading>Related documents</heading>
247 There are several other documents other than this Policy Manual
248 that are necessary to fully understand some Debian policies and
253 The external "sub-policy" documents are referred to in:
254 <list compact="compact">
255 <item><ref id="fhs"></item>
256 <item><ref id="virtual_pkg"></item>
257 <item><ref id="menus"></item>
258 <item><ref id="mime"></item>
259 <item><ref id="perl"></item>
260 <item><ref id="maintscriptprompt"></item>
261 <item><ref id="emacs"></item>
266 In addition to those, which carry the weight of policy, there
267 is the Debian Developer's Reference. This document describes
268 procedures and resources for Debian developers, but it is
269 <em>not</em> normative; rather, it includes things that don't
270 belong in the Policy, such as best practices for developers.
274 The Developer's Reference is available in the
275 <package>developers-reference</package> package.
276 It's also available from the Debian web mirrors at
277 <tt><url name="/doc/developers-reference/"
278 id="http://www.debian.org/doc/developers-reference/"></tt>.
282 <sect id="definitions">
283 <heading>Definitions</heading>
286 The following terms are used in this Policy Manual:
290 The character encoding specified by ANSI X3.4-1986 and its
291 predecessor standards, referred to in MIME as US-ASCII, and
292 corresponding to an encoding in eight bits per character of
293 the first 128 <url id="http://www.unicode.org/"
294 name="Unicode"> characters, with the eighth bit always zero.
298 The transformation format (sometimes called encoding) of
299 <url id="http://www.unicode.org/" name="Unicode"> defined by
300 <url id="http://www.rfc-editor.org/rfc/rfc3629.txt"
301 name="RFC 3629">. UTF-8 has the useful property of having
302 ASCII as a subset, so any text encoded in ASCII is trivially
312 <heading>The Debian Archive</heading>
315 The Debian GNU/Linux system is maintained and distributed as a
316 collection of <em>packages</em>. Since there are so many of
317 them (currently well over 15000), they are split into
318 <em>sections</em> and given <em>priorities</em> to simplify
319 the handling of them.
323 The effort of the Debian project is to build a free operating
324 system, but not every package we want to make accessible is
325 <em>free</em> in our sense (see the Debian Free Software
326 Guidelines, below), or may be imported/exported without
327 restrictions. Thus, the archive is split into areas<footnote>
328 The Debian archive software uses the term "component" internally
329 and in the Release file format to refer to the division of an
330 archive. The Debian Social Contract simply refers to "areas."
331 This document uses terminology similar to the Social Contract.
332 </footnote> based on their licenses and other restrictions.
336 The aims of this are:
338 <list compact="compact">
339 <item>to allow us to make as much software available as we can</item>
340 <item>to allow us to encourage everyone to write free software,
342 <item>to allow us to make it easy for people to produce
343 CD-ROMs of our system without violating any licenses,
344 import/export restrictions, or any other laws.</item>
349 The <em>main</em> archive area forms the <em>Debian GNU/Linux
354 Packages in the other archive areas (<tt>contrib</tt>,
355 <tt>non-free</tt>) are not considered to be part of the Debian
356 distribution, although we support their use and provide
357 infrastructure for them (such as our bug-tracking system and
358 mailing lists). This Debian Policy Manual applies to these
363 <heading>The Debian Free Software Guidelines</heading>
365 The Debian Free Software Guidelines (DFSG) form our
366 definition of "free software". These are:
368 <tag>1. Free Redistribution
371 The license of a Debian component may not restrict any
372 party from selling or giving away the software as a
373 component of an aggregate software distribution
374 containing programs from several different
375 sources. The license may not require a royalty or
376 other fee for such sale.
381 The program must include source code, and must allow
382 distribution in source code as well as compiled form.
384 <tag>3. Derived Works
387 The license must allow modifications and derived
388 works, and must allow them to be distributed under the
389 same terms as the license of the original software.
391 <tag>4. Integrity of The Author's Source Code
394 The license may restrict source-code from being
395 distributed in modified form <em>only</em> if the
396 license allows the distribution of "patch files"
397 with the source code for the purpose of modifying the
398 program at build time. The license must explicitly
399 permit distribution of software built from modified
400 source code. The license may require derived works to
401 carry a different name or version number from the
402 original software. (This is a compromise. The Debian
403 Project encourages all authors to not restrict any
404 files, source or binary, from being modified.)
406 <tag>5. No Discrimination Against Persons or Groups
409 The license must not discriminate against any person
412 <tag>6. No Discrimination Against Fields of Endeavor
415 The license must not restrict anyone from making use
416 of the program in a specific field of endeavor. For
417 example, it may not restrict the program from being
418 used in a business, or from being used for genetic
421 <tag>7. Distribution of License
424 The rights attached to the program must apply to all
425 to whom the program is redistributed without the need
426 for execution of an additional license by those
429 <tag>8. License Must Not Be Specific to Debian
432 The rights attached to the program must not depend on
433 the program's being part of a Debian system. If the
434 program is extracted from Debian and used or
435 distributed without Debian but otherwise within the
436 terms of the program's license, all parties to whom
437 the program is redistributed must have the same
438 rights as those that are granted in conjunction with
441 <tag>9. License Must Not Contaminate Other Software
444 The license must not place restrictions on other
445 software that is distributed along with the licensed
446 software. For example, the license must not insist
447 that all other programs distributed on the same medium
448 must be free software.
450 <tag>10. Example Licenses
453 The "GPL," "BSD," and "Artistic" licenses are examples of
454 licenses that we consider <em>free</em>.
461 <heading>Archive areas</heading>
464 <heading>The main archive area</heading>
467 Every package in <em>main</em> must comply with the DFSG
468 (Debian Free Software Guidelines).
472 In addition, the packages in <em>main</em>
473 <list compact="compact">
475 must not require a package outside of <em>main</em>
476 for compilation or execution (thus, the package must
477 not declare a "Depends", "Recommends", or
478 "Build-Depends" relationship on a non-<em>main</em>
482 must not be so buggy that we refuse to support them,
486 must meet all policy requirements presented in this
495 <heading>The contrib archive area</heading>
498 Every package in <em>contrib</em> must comply with the DFSG.
502 In addition, the packages in <em>contrib</em>
503 <list compact="compact">
505 must not be so buggy that we refuse to support them,
509 must meet all policy requirements presented in this
517 Examples of packages which would be included in
518 <em>contrib</em> are:
519 <list compact="compact">
521 free packages which require <em>contrib</em>,
522 <em>non-free</em> packages or packages which are not
523 in our archive at all for compilation or execution,
527 wrapper packages or other sorts of free accessories for
534 <sect1 id="non-free">
535 <heading>The non-free archive area</heading>
538 Packages must be placed in <em>non-free</em> if they are
539 not compliant with the DFSG or are encumbered by patents
540 or other legal issues that make their distribution
545 In addition, the packages in <em>non-free</em>
546 <list compact="compact">
548 must not be so buggy that we refuse to support them,
552 must meet all policy requirements presented in this
553 manual that it is possible for them to meet.
555 It is possible that there are policy
556 requirements which the package is unable to
557 meet, for example, if the source is
558 unavailable. These situations will need to be
559 handled on a case-by-case basis.
568 <sect id="pkgcopyright">
569 <heading>Copyright considerations</heading>
572 Every package must be accompanied by a verbatim copy of its
573 copyright information and distribution license in the file
574 <file>/usr/share/doc/<var>package</var>/copyright</file>
575 (see <ref id="copyrightfile"> for further details).
579 We reserve the right to restrict files from being included
580 anywhere in our archives if
581 <list compact="compact">
583 their use or distribution would break a law,
586 there is an ethical conflict in their distribution or
590 we would have to sign a license for them, or
593 their distribution would conflict with other project
600 Programs whose authors encourage the user to make
601 donations are fine for the main distribution, provided
602 that the authors do not claim that not donating is
603 immoral, unethical, illegal or something similar; in such
604 a case they must go in <em>non-free</em>.
608 Packages whose copyright permission notices (or patent
609 problems) do not even allow redistribution of binaries
610 only, and where no special permission has been obtained,
611 must not be placed on the Debian FTP site and its mirrors
616 Note that under international copyright law (this applies
617 in the United States, too), <em>no</em> distribution or
618 modification of a work is allowed without an explicit
619 notice saying so. Therefore a program without a copyright
620 notice <em>is</em> copyrighted and you may not do anything
621 to it without risking being sued! Likewise if a program
622 has a copyright notice but no statement saying what is
623 permitted then nothing is permitted.
627 Many authors are unaware of the problems that restrictive
628 copyrights (or lack of copyright notices) can cause for
629 the users of their supposedly-free software. It is often
630 worthwhile contacting such authors diplomatically to ask
631 them to modify their license terms. However, this can be a
632 politically difficult thing to do and you should ask for
633 advice on the <tt>debian-legal</tt> mailing list first, as
638 When in doubt about a copyright, send mail to
639 <email>debian-legal@lists.debian.org</email>. Be prepared
640 to provide us with the copyright statement. Software
641 covered by the GPL, public domain software and BSD-like
642 copyrights are safe; be wary of the phrases "commercial
643 use prohibited" and "distribution restricted".
647 <sect id="subsections">
648 <heading>Sections</heading>
651 The packages in the archive areas <em>main</em>,
652 <em>contrib</em> and <em>non-free</em> are grouped further into
653 <em>sections</em> to simplify handling.
657 The archive area and section for each package should be
658 specified in the package's <tt>Section</tt> control record (see
659 <ref id="f-Section">). However, the maintainer of the Debian
660 archive may override this selection to ensure the consistency of
661 the Debian distribution. The <tt>Section</tt> field should be
663 <list compact="compact">
665 <em>section</em> if the package is in the
666 <em>main</em> archive area,
669 <em>area/section</em> if the package is in
670 the <em>contrib</em> or <em>non-free</em>
677 The Debian archive maintainers provide the authoritative
678 list of sections. At present, they are:
679 <em>admin</em>, <em>cli-mono</em>, <em>comm</em>, <em>database</em>,
680 <em>devel</em>, <em>debug</em>, <em>doc</em>, <em>editors</em>,
681 <em>electronics</em>, <em>embedded</em>, <em>fonts</em>,
682 <em>games</em>, <em>gnome</em>, <em>graphics</em>, <em>gnu-r</em>,
683 <em>gnustep</em>, <em>hamradio</em>, <em>haskell</em>,
684 <em>httpd</em>, <em>interpreters</em>, <em>java</em>, <em>kde</em>,
685 <em>kernel</em>, <em>libs</em>, <em>libdevel</em>, <em>lisp</em>,
686 <em>localization</em>, <em>mail</em>, <em>math</em>, <em>misc</em>,
687 <em>net</em>, <em>news</em>, <em>ocaml</em>, <em>oldlibs</em>,
688 <em>otherosfs</em>, <em>perl</em>, <em>php</em>, <em>python</em>,
689 <em>ruby</em>, <em>science</em>, <em>shells</em>, <em>sound</em>,
690 <em>tex</em>, <em>text</em>, <em>utils</em>, <em>vcs</em>,
691 <em>video</em>, <em>web</em>, <em>x11</em>, <em>xfce</em>,
692 <em>zope</em>. The additional section <em>debian-installer</em>
693 contains special packages used by the installer and is not used
694 for normal Debian packages.
698 For more information about the sections and their definitions,
699 see the <url id="http://packages.debian.org/unstable/"
700 name="list of sections in unstable">.
704 <sect id="priorities">
705 <heading>Priorities</heading>
708 Each package should have a <em>priority</em> value, which is
709 included in the package's <em>control record</em>
710 (see <ref id="f-Priority">).
711 This information is used by the Debian package management tools to
712 separate high-priority packages from less-important packages.
716 The following <em>priority levels</em> are recognized by the
717 Debian package management tools.
719 <tag><tt>required</tt></tag>
721 Packages which are necessary for the proper
722 functioning of the system (usually, this means that
723 dpkg functionality depends on these packages).
724 Removing a <tt>required</tt> package may cause your
725 system to become totally broken and you may not even
726 be able to use <prgn>dpkg</prgn> to put things back,
727 so only do so if you know what you are doing. Systems
728 with only the <tt>required</tt> packages are probably
729 unusable, but they do have enough functionality to
730 allow the sysadmin to boot and install more software.
732 <tag><tt>important</tt></tag>
734 Important programs, including those which one would
735 expect to find on any Unix-like system. If the
736 expectation is that an experienced Unix person who
737 found it missing would say "What on earth is going on,
738 where is <prgn>foo</prgn>?", it must be an
739 <tt>important</tt> package.<footnote>
740 This is an important criterion because we are
741 trying to produce, amongst other things, a free
744 Other packages without which the system will not run
745 well or be usable must also have priority
746 <tt>important</tt>. This does
747 <em>not</em> include Emacs, the X Window System, TeX
748 or any other large applications. The
749 <tt>important</tt> packages are just a bare minimum of
750 commonly-expected and necessary tools.
752 <tag><tt>standard</tt></tag>
754 These packages provide a reasonably small but not too
755 limited character-mode system. This is what will be
756 installed by default if the user doesn't select anything
757 else. It doesn't include many large applications.
759 <tag><tt>optional</tt></tag>
761 (In a sense everything that isn't required is
762 optional, but that's not what is meant here.) This is
763 all the software that you might reasonably want to
764 install if you didn't know what it was and don't have
765 specialized requirements. This is a much larger system
766 and includes the X Window System, a full TeX
767 distribution, and many applications. Note that
768 optional packages should not conflict with each other.
770 <tag><tt>extra</tt></tag>
772 This contains all packages that conflict with others
773 with required, important, standard or optional
774 priorities, or are only likely to be useful if you
775 already know what they are or have specialized
776 requirements (such as packages containing only detached
783 Packages must not depend on packages with lower priority
784 values (excluding build-time dependencies). In order to
785 ensure this, the priorities of one or more packages may need
794 <heading>Binary packages</heading>
797 The Debian GNU/Linux distribution is based on the Debian
798 package management system, called <prgn>dpkg</prgn>. Thus,
799 all packages in the Debian distribution must be provided
800 in the <tt>.deb</tt> file format.
804 <heading>The package name</heading>
807 Every package must have a name that's unique within the Debian
812 The package name is included in the control field
813 <tt>Package</tt>, the format of which is described
814 in <ref id="f-Package">.
815 The package name is also included as a part of the file name
816 of the <tt>.deb</tt> file.
821 <heading>The version of a package</heading>
824 Every package has a version number recorded in its
825 <tt>Version</tt> control file field, described in
826 <ref id="f-Version">.
830 The package management system imposes an ordering on version
831 numbers, so that it can tell whether packages are being up- or
832 downgraded and so that package system front end applications
833 can tell whether a package it finds available is newer than
834 the one installed on the system. The version number format
835 has the most significant parts (as far as comparison is
836 concerned) at the beginning.
840 If an upstream package has problematic version numbers they
841 should be converted to a sane form for use in the
842 <tt>Version</tt> field.
846 <heading>Version numbers based on dates</heading>
849 In general, Debian packages should use the same version
850 numbers as the upstream sources.
854 However, in some cases where the upstream version number is
855 based on a date (e.g., a development "snapshot" release) the
856 package management system cannot handle these version
857 numbers without epochs. For example, dpkg will consider
858 "96May01" to be greater than "96Dec24".
862 To prevent having to use epochs for every new upstream
863 version, the date based portion of the version number
864 should be changed to the following format in such cases:
865 "19960501", "19961224". It is up to the maintainer whether
866 they want to bother the upstream maintainer to change
867 the version numbers upstream, too.
871 Note that other version formats based on dates which are
872 parsed correctly by the package management system should
873 <em>not</em> be changed.
877 Native Debian packages (i.e., packages which have been
878 written especially for Debian) whose version numbers include
879 dates should always use the "YYYYMMDD" format.
886 <heading>The maintainer of a package</heading>
889 Every package must have a Debian maintainer (the
890 maintainer may be one person or a group of people
891 reachable from a common email address, such as a mailing
892 list). The maintainer is responsible for ensuring that
893 the package is placed in the appropriate distributions.
897 The maintainer must be specified in the
898 <tt>Maintainer</tt> control field with their correct name
899 and a working email address. If one person maintains
900 several packages, they should try to avoid having
901 different forms of their name and email address in
902 the <tt>Maintainer</tt> fields of those packages.
906 The format of the <tt>Maintainer</tt> control field is
907 described in <ref id="f-Maintainer">.
911 If the maintainer of a package quits from the Debian
912 project, "Debian QA Group"
913 <email>packages@qa.debian.org</email> takes over the
914 maintainer-ship of the package until someone else
915 volunteers for that task. These packages are called
916 <em>orphaned packages</em>.<footnote>
917 The detailed procedure for doing this gracefully can
918 be found in the Debian Developer's Reference,
919 see <ref id="related">.
924 <sect id="descriptions">
925 <heading>The description of a package</heading>
928 Every Debian package must have an extended description
929 stored in the appropriate field of the control record.
930 The technical information about the format of the
931 <tt>Description</tt> field is in <ref id="f-Description">.
935 The description should describe the package (the program) to a
936 user (system administrator) who has never met it before so that
937 they have enough information to decide whether they want to
938 install it. This description should not just be copied verbatim
939 from the program's documentation.
943 Put important information first, both in the synopsis and
944 extended description. Sometimes only the first part of the
945 synopsis or of the description will be displayed. You can
946 assume that there will usually be a way to see the whole
947 extended description.
951 The description should also give information about the
952 significant dependencies and conflicts between this package
953 and others, so that the user knows why these dependencies and
954 conflicts have been declared.
958 Instructions for configuring or using the package should
959 not be included (that is what installation scripts,
960 manual pages, info files, etc., are for). Copyright
961 statements and other administrivia should not be included
962 either (that is what the copyright file is for).
965 <sect1 id="synopsis"><heading>The single line synopsis</heading>
968 The single line synopsis should be kept brief - certainly
973 Do not include the package name in the synopsis line. The
974 display software knows how to display this already, and you
975 do not need to state it. Remember that in many situations
976 the user may only see the synopsis line - make it as
977 informative as you can.
982 <sect1 id="extendeddesc"><heading>The extended description</heading>
985 Do not try to continue the single line synopsis into the
986 extended description. This will not work correctly when
987 the full description is displayed, and makes no sense
988 where only the summary (the single line synopsis) is
993 The extended description should describe what the package
994 does and how it relates to the rest of the system (in terms
995 of, for example, which subsystem it is which part of).
999 The description field needs to make sense to anyone, even
1000 people who have no idea about any of the things the
1001 package deals with.<footnote>
1002 The blurb that comes with a program in its
1003 announcements and/or <prgn>README</prgn> files is
1004 rarely suitable for use in a description. It is
1005 usually aimed at people who are already in the
1006 community where the package is used.
1015 <heading>Dependencies</heading>
1018 Every package must specify the dependency information
1019 about other packages that are required for the first to
1024 For example, a dependency entry must be provided for any
1025 shared libraries required by a dynamically-linked executable
1026 binary in a package.
1030 Packages are not required to declare any dependencies they
1031 have on other packages which are marked <tt>Essential</tt>
1032 (see below), and should not do so unless they depend on a
1033 particular version of that package.<footnote>
1035 Essential is needed in part to avoid unresolvable dependency
1036 loops on upgrade. If packages add unnecessary dependencies
1037 on packages in this set, the chances that there
1038 <strong>will</strong> be an unresolvable dependency loop
1039 caused by forcing these Essential packages to be configured
1040 first before they need to be is greatly increased. It also
1041 increases the chances that frontends will be unable to
1042 <strong>calculate</strong> an upgrade path, even if one
1046 Also, functionality is rarely ever removed from the
1047 Essential set, but <em>packages</em> have been removed from
1048 the Essential set when the functionality moved to a
1049 different package. So depending on these packages <em>just
1050 in case</em> they stop being essential does way more harm
1057 Sometimes, a package requires another package to be installed
1058 <em>and</em> configured before it can be installed. In this
1059 case, you must specify a <tt>Pre-Depends</tt> entry for
1064 You should not specify a <tt>Pre-Depends</tt> entry for a
1065 package before this has been discussed on the
1066 <tt>debian-devel</tt> mailing list and a consensus about
1067 doing that has been reached.
1071 The format of the package interrelationship control fields is
1072 described in <ref id="relationships">.
1076 <sect id="virtual_pkg">
1077 <heading>Virtual packages</heading>
1080 Sometimes, there are several packages which offer
1081 more-or-less the same functionality. In this case, it's
1082 useful to define a <em>virtual package</em> whose name
1083 describes that common functionality. (The virtual
1084 packages only exist logically, not physically; that's why
1085 they are called <em>virtual</em>.) The packages with this
1086 particular function will then <em>provide</em> the virtual
1087 package. Thus, any other package requiring that function
1088 can simply depend on the virtual package without having to
1089 specify all possible packages individually.
1093 All packages should use virtual package names where
1094 appropriate, and arrange to create new ones if necessary.
1095 They should not use virtual package names (except privately,
1096 amongst a cooperating group of packages) unless they have
1097 been agreed upon and appear in the list of virtual package
1098 names. (See also <ref id="virtual">)
1102 The latest version of the authoritative list of virtual
1103 package names can be found in the <tt>debian-policy</tt> package.
1104 It is also available from the Debian web mirrors at
1105 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1106 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>.
1110 The procedure for updating the list is described in the preface
1117 <heading>Base system</heading>
1120 The <tt>base system</tt> is a minimum subset of the Debian
1121 GNU/Linux system that is installed before everything else
1122 on a new system. Only very few packages are allowed to form
1123 part of the base system, in order to keep the required disk
1128 The base system consists of all those packages with priority
1129 <tt>required</tt> or <tt>important</tt>. Many of them will
1130 be tagged <tt>essential</tt> (see below).
1135 <heading>Essential packages</heading>
1138 Essential is defined as the minimal set of functionality that
1139 must be available and usable on the system at all times, even
1140 when packages are in an unconfigured (but unpacked) state.
1141 Packages are tagged <tt>essential</tt> for a system using the
1142 <tt>Essential</tt> control file field. The format of the
1143 <tt>Essential</tt> control field is described in <ref
1148 Since these packages cannot be easily removed (one has to
1149 specify an extra <em>force option</em> to
1150 <prgn>dpkg</prgn> to do so), this flag must not be used
1151 unless absolutely necessary. A shared library package
1152 must not be tagged <tt>essential</tt>; dependencies will
1153 prevent its premature removal, and we need to be able to
1154 remove it when it has been superseded.
1158 Since dpkg will not prevent upgrading of other packages
1159 while an <tt>essential</tt> package is in an unconfigured
1160 state, all <tt>essential</tt> packages must supply all of
1161 their core functionality even when unconfigured. If the
1162 package cannot satisfy this requirement it must not be
1163 tagged as essential, and any packages depending on this
1164 package must instead have explicit dependency fields as
1169 Maintainers should take great care in adding any programs,
1170 interfaces, or functionality to <tt>essential</tt> packages.
1171 Packages may assume that functionality provided by
1172 <tt>essential</tt> packages is always available without
1173 declaring explicit dependencies, which means that removing
1174 functionality from the Essential set is very difficult and is
1175 almost never done. Any capability added to an
1176 <tt>essential</tt> package therefore creates an obligation to
1177 support that capability as part of the Essential set in
1182 You must not tag any packages <tt>essential</tt> before
1183 this has been discussed on the <tt>debian-devel</tt>
1184 mailing list and a consensus about doing that has been
1189 <sect id="maintscripts">
1190 <heading>Maintainer Scripts</heading>
1193 The package installation scripts should avoid producing
1194 output which is unnecessary for the user to see and
1195 should rely on <prgn>dpkg</prgn> to stave off boredom on
1196 the part of a user installing many packages. This means,
1197 amongst other things, using the <tt>--quiet</tt> option on
1198 <prgn>install-info</prgn>.
1202 Errors which occur during the execution of an installation
1203 script must be checked and the installation must not
1204 continue after an error.
1208 Note that in general <ref id="scripts"> applies to package
1209 maintainer scripts, too.
1213 You should not use <prgn>dpkg-divert</prgn> on a file
1214 belonging to another package without consulting the
1215 maintainer of that package first.
1219 All packages which supply an instance of a common command
1220 name (or, in general, filename) should generally use
1221 <prgn>update-alternatives</prgn>, so that they may be
1222 installed together. If <prgn>update-alternatives</prgn>
1223 is not used, then each package must use
1224 <tt>Conflicts</tt> to ensure that other packages are
1225 de-installed. (In this case, it may be appropriate to
1226 specify a conflict against earlier versions of something
1227 that previously did not use
1228 <prgn>update-alternatives</prgn>; this is an exception to
1229 the usual rule that versioned conflicts should be
1233 <sect1 id="maintscriptprompt">
1234 <heading>Prompting in maintainer scripts</heading>
1236 Package maintainer scripts may prompt the user if
1237 necessary. Prompting must be done by communicating
1238 through a program, such as <prgn>debconf</prgn>, which
1239 conforms to the Debian Configuration Management
1240 Specification, version 2 or higher.
1244 Packages which are essential, or which are dependencies of
1245 essential packages, may fall back on another prompting method
1246 if no such interface is available when they are executed.
1250 The Debian Configuration Management Specification is included
1251 in the <file>debconf_specification</file> files in the
1252 <package>debian-policy</package> package.
1253 It is also available from the Debian web mirrors at
1254 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1255 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>.
1259 Packages which use the Debian Configuration Management
1260 Specification may contain an additional
1261 <prgn>config</prgn> script and a <tt>templates</tt>
1262 file in their control archive<footnote>
1263 The control.tar.gz inside the .deb.
1264 See <manref name="deb" section="5">.
1266 The <prgn>config</prgn> script might be run before the
1267 <prgn>preinst</prgn> script, and before the package is unpacked
1268 or any of its dependencies or pre-dependencies are satisfied.
1269 Therefore it must work using only the tools present in
1270 <em>essential</em> packages.<footnote>
1271 <package>Debconf</package> or another tool that
1272 implements the Debian Configuration Management
1273 Specification will also be installed, and any
1274 versioned dependencies on it will be satisfied
1275 before preconfiguration begins.
1280 Packages which use the Debian Configuration Management
1281 Specification must allow for translation of their user-visible
1282 messages by using a gettext-based system such as the one
1283 provided by the <package>po-debconf</package> package.
1287 Packages should try to minimize the amount of prompting
1288 they need to do, and they should ensure that the user
1289 will only ever be asked each question once. This means
1290 that packages should try to use appropriate shared
1291 configuration files (such as <file>/etc/papersize</file> and
1292 <file>/etc/news/server</file>), and shared
1293 <package>debconf</package> variables rather than each
1294 prompting for their own list of required pieces of
1299 It also means that an upgrade should not ask the same
1300 questions again, unless the user has used
1301 <tt>dpkg --purge</tt> to remove the package's configuration.
1302 The answers to configuration questions should be stored in an
1303 appropriate place in <file>/etc</file> so that the user can
1304 modify them, and how this has been done should be
1309 If a package has a vitally important piece of
1310 information to pass to the user (such as "don't run me
1311 as I am, you must edit the following configuration files
1312 first or you risk your system emitting badly-formatted
1313 messages"), it should display this in the
1314 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1315 prompt the user to hit return to acknowledge the
1316 message. Copyright messages do not count as vitally
1317 important (they belong in
1318 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1319 neither do instructions on how to use a program (these
1320 should be in on-line documentation, where all the users
1325 Any necessary prompting should almost always be confined
1326 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1327 script. If it is done in the <prgn>postinst</prgn>, it
1328 should be protected with a conditional so that
1329 unnecessary prompting doesn't happen if a package's
1330 installation fails and the <prgn>postinst</prgn> is
1331 called with <tt>abort-upgrade</tt>,
1332 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1342 <heading>Source packages</heading>
1344 <sect id="standardsversion">
1345 <heading>Standards conformance</heading>
1348 Source packages should specify the most recent version number
1349 of this policy document with which your package complied
1350 when it was last updated.
1354 This information may be used to file bug reports
1355 automatically if your package becomes too much out of date.
1359 The version is specified in the <tt>Standards-Version</tt>
1361 The format of the <tt>Standards-Version</tt> field is
1362 described in <ref id="f-Standards-Version">.
1366 You should regularly, and especially if your package has
1367 become out of date, check for the newest Policy Manual
1368 available and update your package, if necessary. When your
1369 package complies with the new standards you should update the
1370 <tt>Standards-Version</tt> source package field and
1371 release it.<footnote>
1372 See the file <file>upgrading-checklist</file> for
1373 information about policy which has changed between
1374 different versions of this document.
1380 <sect id="pkg-relations">
1381 <heading>Package relationships</heading>
1384 Source packages should specify which binary packages they
1385 require to be installed or not to be installed in order to
1386 build correctly. For example, if building a package
1387 requires a certain compiler, then the compiler should be
1388 specified as a build-time dependency.
1392 It is not necessary to explicitly specify build-time
1393 relationships on a minimal set of packages that are always
1394 needed to compile, link and put in a Debian package a
1395 standard "Hello World!" program written in C or C++. The
1396 required packages are called <em>build-essential</em>, and
1397 an informational list can be found in
1398 <file>/usr/share/doc/build-essential/list</file> (which is
1399 contained in the <tt>build-essential</tt>
1402 <list compact="compact">
1404 This allows maintaining the list separately
1405 from the policy documents (the list does not
1406 need the kind of control that the policy
1410 Having a separate package allows one to install
1411 the build-essential packages on a machine, as
1412 well as allowing other packages such as tasks to
1413 require installation of the build-essential
1414 packages using the depends relation.
1417 The separate package allows bug reports against
1418 the list to be categorized separately from
1419 the policy management process in the BTS.
1426 When specifying the set of build-time dependencies, one
1427 should list only those packages explicitly required by the
1428 build. It is not necessary to list packages which are
1429 required merely because some other package in the list of
1430 build-time dependencies depends on them.<footnote>
1431 The reason for this is that dependencies change, and
1432 you should list all those packages, and <em>only</em>
1433 those packages that <em>you</em> need directly. What
1434 others need is their business. For example, if you
1435 only link against <file>libimlib</file>, you will need to
1436 build-depend on <package>libimlib2-dev</package> but
1437 not against any <tt>libjpeg*</tt> packages, even
1438 though <tt>libimlib2-dev</tt> currently depends on
1439 them: installation of <package>libimlib2-dev</package>
1440 will automatically ensure that all of its run-time
1441 dependencies are satisfied.
1446 If build-time dependencies are specified, it must be
1447 possible to build the package and produce working binaries
1448 on a system with only essential and build-essential
1449 packages installed and also those required to satisfy the
1450 build-time relationships (including any implied
1451 relationships). In particular, this means that version
1452 clauses should be used rigorously in build-time
1453 relationships so that one cannot produce bad or
1454 inconsistently configured packages when the relationships
1455 are properly satisfied.
1459 <ref id="relationships"> explains the technical details.
1464 <heading>Changes to the upstream sources</heading>
1467 If changes to the source code are made that are not
1468 specific to the needs of the Debian system, they should be
1469 sent to the upstream authors in whatever form they prefer
1470 so as to be included in the upstream version of the
1475 If you need to configure the package differently for
1476 Debian or for Linux, and the upstream source doesn't
1477 provide a way to do so, you should add such configuration
1478 facilities (for example, a new <prgn>autoconf</prgn> test
1479 or <tt>#define</tt>) and send the patch to the upstream
1480 authors, with the default set to the way they originally
1481 had it. You can then easily override the default in your
1482 <file>debian/rules</file> or wherever is appropriate.
1486 You should make sure that the <prgn>configure</prgn> utility
1487 detects the correct architecture specification string
1488 (refer to <ref id="arch-spec"> for details).
1492 If you need to edit a <prgn>Makefile</prgn> where GNU-style
1493 <prgn>configure</prgn> scripts are used, you should edit the
1494 <file>.in</file> files rather than editing the
1495 <prgn>Makefile</prgn> directly. This allows the user to
1496 reconfigure the package if necessary. You should
1497 <em>not</em> configure the package and edit the generated
1498 <prgn>Makefile</prgn>! This makes it impossible for someone
1499 else to later reconfigure the package without losing the
1505 <sect id="dpkgchangelog">
1506 <heading>Debian changelog: <file>debian/changelog</file></heading>
1509 Changes in the Debian version of the package should be
1510 briefly explained in the Debian changelog file
1511 <file>debian/changelog</file>.<footnote>
1513 Mistakes in changelogs are usually best rectified by
1514 making a new changelog entry rather than "rewriting
1515 history" by editing old changelog entries.
1518 This includes modifications
1519 made in the Debian package compared to the upstream one
1520 as well as other changes and updates to the package.
1522 Although there is nothing stopping an author who is also
1523 the Debian maintainer from using this changelog for all
1524 their changes, it will have to be renamed if the Debian
1525 and upstream maintainers become different people. In such
1526 a case, however, it might be better to maintain the package
1527 as a non-native package.
1532 The format of the <file>debian/changelog</file> allows the
1533 package building tools to discover which version of the package
1534 is being built and find out other release-specific information.
1538 That format is a series of entries like this:
1540 <example compact="compact">
1541 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1543 [optional blank line(s), stripped]
1545 * <var>change details</var>
1546 <var>more change details</var>
1548 [blank line(s), included in output of dpkg-parsechangelog]
1550 * <var>even more change details</var>
1552 [optional blank line(s), stripped]
1554 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1559 <var>package</var> and <var>version</var> are the source
1560 package name and version number.
1564 <var>distribution(s)</var> lists the distributions where
1565 this version should be installed when it is uploaded - it
1566 is copied to the <tt>Distribution</tt> field in the
1567 <file>.changes</file> file. See <ref id="f-Distribution">.
1571 <var>urgency</var> is the value for the <tt>Urgency</tt>
1572 field in the <file>.changes</file> file for the upload
1573 (see <ref id="f-Urgency">). It is not possible to specify
1574 an urgency containing commas; commas are used to separate
1575 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1576 <prgn>dpkg</prgn> changelog format (though there is
1577 currently only one useful <var>keyword</var>,
1582 The change details may in fact be any series of lines
1583 starting with at least two spaces, but conventionally each
1584 change starts with an asterisk and a separating space and
1585 continuation lines are indented so as to bring them in
1586 line with the start of the text above. Blank lines may be
1587 used here to separate groups of changes, if desired.
1591 If this upload resolves bugs recorded in the Bug Tracking
1592 System (BTS), they may be automatically closed on the
1593 inclusion of this package into the Debian archive by
1594 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1595 in the change details.<footnote>
1596 To be precise, the string should match the following
1597 Perl regular expression:
1599 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1601 Then all of the bug numbers listed will be closed by the
1602 archive maintenance script (<prgn>katie</prgn>) using the
1603 <var>version</var> of the changelog entry.
1605 This information is conveyed via the <tt>Closes</tt> field
1606 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1610 The maintainer name and email address used in the changelog
1611 should be the details of the person uploading <em>this</em>
1612 version. They are <em>not</em> necessarily those of the
1613 usual package maintainer. The information here will be
1614 copied to the <tt>Changed-By</tt> field in the
1615 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1616 and then later used to send an acknowledgement when the
1617 upload has been installed.
1621 The <var>date</var> must be in RFC822 format<footnote>
1622 This is generated by <tt>date -R</tt>.
1623 </footnote>; it must include the time zone specified
1624 numerically, with the time zone name or abbreviation
1625 optionally present as a comment in parentheses.
1629 The first "title" line with the package name must start
1630 at the left hand margin. The "trailer" line with the
1631 maintainer and date details must be preceded by exactly
1632 one space. The maintainer details and the date must be
1633 separated by exactly two spaces.
1637 The entire changelog must be encoded in UTF-8.
1641 For more information on placement of the changelog files
1642 within binary packages, please see <ref id="changelogs">.
1646 <sect id="dpkgcopyright">
1647 <heading>Copyright: <file>debian/copyright</file></heading>
1649 Every package must be accompanied by a verbatim copy of its
1650 copyright information and distribution license in the file
1651 <file>/usr/share/doc/<var>package</var>/copyright</file>
1652 (see <ref id="copyrightfile"> for further details). Also see
1653 <ref id="pkgcopyright"> for further considerations related
1654 to copyrights for packages.
1658 <heading>Error trapping in makefiles</heading>
1661 When <prgn>make</prgn> invokes a command in a makefile
1662 (including your package's upstream makefiles and
1663 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1664 means that <prgn>sh</prgn>'s usual bad error handling
1665 properties apply: if you include a miniature script as one
1666 of the commands in your makefile you'll find that if you
1667 don't do anything about it then errors are not detected
1668 and <prgn>make</prgn> will blithely continue after
1673 Every time you put more than one shell command (this
1674 includes using a loop) in a makefile command you
1675 must make sure that errors are trapped. For
1676 simple compound commands, such as changing directory and
1677 then running a program, using <tt>&&</tt> rather
1678 than semicolon as a command separator is sufficient. For
1679 more complex commands including most loops and
1680 conditionals you should include a separate <tt>set -e</tt>
1681 command at the start of every makefile command that's
1682 actually one of these miniature shell scripts.
1686 <sect id="timestamps">
1687 <heading>Time Stamps</heading>
1689 Maintainers should preserve the modification times of the
1690 upstream source files in a package, as far as is reasonably
1692 The rationale is that there is some information conveyed
1693 by knowing the age of the file, for example, you could
1694 recognize that some documentation is very old by looking
1695 at the modification time, so it would be nice if the
1696 modification time of the upstream source would be
1702 <sect id="restrictions">
1703 <heading>Restrictions on objects in source packages</heading>
1706 The source package may not contain any hard links<footnote>
1708 This is not currently detected when building source
1709 packages, but only when extracting
1713 Hard links may be permitted at some point in the
1714 future, but would require a fair amount of
1717 </footnote>, device special files, sockets or setuid or
1718 setgid files.<footnote>
1719 Setgid directories are allowed.
1724 <sect id="debianrules">
1725 <heading>Main building script: <file>debian/rules</file></heading>
1728 This file must be an executable makefile, and contains the
1729 package-specific recipes for compiling the package and
1730 building binary package(s) from the source.
1734 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1735 so that it can be invoked by saying its name rather than
1736 invoking <prgn>make</prgn> explicitly. That is, invoking
1737 either of <tt>make -f debian/rules <em>args...</em></tt>
1738 or <tt>./debian/rules <em>args...</em></tt> must result in
1743 Since an interactive <file>debian/rules</file> script makes it
1744 impossible to auto-compile that package and also makes it
1745 hard for other people to reproduce the same binary
1746 package, all <em>required targets</em> must be
1747 non-interactive. At a minimum, required targets are the
1748 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1749 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1750 <em>binary-indep</em>, and <em>build</em>. It also follows
1751 that any target that these targets depend on must also be
1756 The targets are as follows (required unless stated otherwise):
1758 <tag><tt>build</tt></tag>
1761 The <tt>build</tt> target should perform all the
1762 configuration and compilation of the package.
1763 If a package has an interactive pre-build
1764 configuration routine, the Debianized source package
1765 must either be built after this has taken place (so
1766 that the binary package can be built without rerunning
1767 the configuration) or the configuration routine
1768 modified to become non-interactive. (The latter is
1769 preferable if there are architecture-specific features
1770 detected by the configuration routine.)
1774 For some packages, notably ones where the same
1775 source tree is compiled in different ways to produce
1776 two binary packages, the <tt>build</tt> target
1777 does not make much sense. For these packages it is
1778 good enough to provide two (or more) targets
1779 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1780 for each of the ways of building the package, and a
1781 <tt>build</tt> target that does nothing. The
1782 <tt>binary</tt> target will have to build the
1783 package in each of the possible ways and make the
1784 binary package out of each.
1788 The <tt>build</tt> target must not do anything
1789 that might require root privilege.
1793 The <tt>build</tt> target may need to run the
1794 <tt>clean</tt> target first - see below.
1798 When a package has a configuration and build routine
1799 which takes a long time, or when the makefiles are
1800 poorly designed, or when <tt>build</tt> needs to
1801 run <tt>clean</tt> first, it is a good idea to
1802 <tt>touch build</tt> when the build process is
1803 complete. This will ensure that if <tt>debian/rules
1804 build</tt> is run again it will not rebuild the whole
1806 Another common way to do this is for <tt>build</tt>
1807 to depend on <prgn>build-stamp</prgn> and to do
1808 nothing else, and for the <prgn>build-stamp</prgn>
1809 target to do the building and to <tt>touch
1810 build-stamp</tt> on completion. This is
1811 especially useful if the build routine creates a
1812 file or directory called <tt>build</tt>; in such a
1813 case, <tt>build</tt> will need to be listed as
1814 a phony target (i.e., as a dependency of the
1815 <tt>.PHONY</tt> target). See the documentation of
1816 <prgn>make</prgn> for more information on phony
1822 <tag><tt>build-arch</tt> (optional),
1823 <tt>build-indep</tt> (optional)
1827 A package may also provide both of the targets
1828 <tt>build-arch</tt> and <tt>build-indep</tt>.
1829 The <tt>build-arch</tt> target, if provided, should
1830 perform all the configuration and compilation required
1831 for producing all architecture-dependant binary packages
1832 (those packages for which the body of the
1833 <tt>Architecture</tt> field in <tt>debian/control</tt>
1834 is not <tt>all</tt>).
1835 Similarly, the <tt>build-indep</tt> target, if
1836 provided, should perform all the configuration and
1837 compilation required for producing all
1838 architecture-independent binary packages
1839 (those packages for which the body of the
1840 <tt>Architecture</tt> field in <tt>debian/control</tt>
1842 The <tt>build</tt> target should depend on those of the
1843 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1844 are provided in the rules file.
1848 If one or both of the targets <tt>build-arch</tt> and
1849 <tt>build-indep</tt> are not provided, then invoking
1850 <file>debian/rules</file> with one of the not-provided
1851 targets as arguments should produce a exit status code
1852 of 2. Usually this is provided automatically by make
1853 if the target is missing.
1857 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1858 must not do anything that might require root privilege.
1862 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1863 <tt>binary-indep</tt>
1867 The <tt>binary</tt> target must be all that is
1868 necessary for the user to build the binary package(s)
1869 produced from this source package. It is
1870 split into two parts: <prgn>binary-arch</prgn> builds
1871 the binary packages which are specific to a particular
1872 architecture, and <tt>binary-indep</tt> builds
1873 those which are not.
1876 <tt>binary</tt> may be (and commonly is) a target with
1877 no commands which simply depends on
1878 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1881 Both <tt>binary-*</tt> targets should depend on the
1882 <tt>build</tt> target, or on the appropriate
1883 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1884 provided, so that the package is built if it has not
1885 been already. It should then create the relevant
1886 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1887 make their control files and <prgn>dpkg-deb</prgn> to
1888 build them and place them in the parent of the top
1893 Both the <tt>binary-arch</tt> and
1894 <tt>binary-indep</tt> targets <em>must</em> exist.
1895 If one of them has nothing to do (which will always be
1896 the case if the source generates only a single binary
1897 package, whether architecture-dependent or not), it
1898 must still exist and must always succeed.
1902 The <tt>binary</tt> targets must be invoked as
1904 The <prgn>fakeroot</prgn> package often allows one
1905 to build a package correctly even without being
1911 <tag><tt>clean</tt></tag>
1914 This must undo any effects that the <tt>build</tt>
1915 and <tt>binary</tt> targets may have had, except
1916 that it should leave alone any output files created in
1917 the parent directory by a run of a <tt>binary</tt>
1922 If a <tt>build</tt> file is touched at the end of
1923 the <tt>build</tt> target, as suggested above, it
1924 should be removed as the first action that
1925 <tt>clean</tt> performs, so that running
1926 <tt>build</tt> again after an interrupted
1927 <tt>clean</tt> doesn't think that everything is
1932 The <tt>clean</tt> target may need to be
1933 invoked as root if <tt>binary</tt> has been
1934 invoked since the last <tt>clean</tt>, or if
1935 <tt>build</tt> has been invoked as root (since
1936 <tt>build</tt> may create directories, for
1941 <tag><tt>get-orig-source</tt> (optional)</tag>
1944 This target fetches the most recent version of the
1945 original source package from a canonical archive site
1946 (via FTP or WWW, for example), does any necessary
1947 rearrangement to turn it into the original source
1948 tar file format described below, and leaves it in the
1953 This target may be invoked in any directory, and
1954 should take care to clean up any temporary files it
1959 This target is optional, but providing it if
1960 possible is a good idea.
1964 <tag><tt>patch</tt> (optional)</tag>
1967 This target performs whatever additional actions are
1968 required to make the source ready for editing (unpacking
1969 additional upstream archives, applying patches, etc.).
1970 It is recommended to be implemented for any package where
1971 <tt>dpkg-source -x</tt> does not result in source ready
1972 for additional modification. See
1973 <ref id="readmesource">.
1979 The <tt>build</tt>, <tt>binary</tt> and
1980 <tt>clean</tt> targets must be invoked with the current
1981 directory being the package's top-level directory.
1986 Additional targets may exist in <file>debian/rules</file>,
1987 either as published or undocumented interfaces or for the
1988 package's internal use.
1992 The architectures we build on and build for are determined
1993 by <prgn>make</prgn> variables using the utility
1994 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
1995 You can determine the
1996 Debian architecture and the GNU style architecture
1997 specification string for the build machine (the machine type
1998 we are building on) as well as for the host machine (the
1999 machine type we are building for). Here is a list of
2000 supported <prgn>make</prgn> variables:
2001 <list compact="compact">
2003 <tt>DEB_*_ARCH</tt> (the Debian architecture)
2006 <tt>DEB_*_ARCH_CPU</tt> (the Debian CPU name)
2009 <tt>DEB_*_ARCH_OS</tt> (the Debian System name)
2012 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2013 specification string)
2016 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2017 <tt>DEB_*_GNU_TYPE</tt>)
2020 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2021 <tt>DEB_*_GNU_TYPE</tt>)
2023 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2024 the build machine or <tt>HOST</tt> for specification of the
2029 Backward compatibility can be provided in the rules file
2030 by setting the needed variables to suitable default
2031 values; please refer to the documentation of
2032 <prgn>dpkg-architecture</prgn> for details.
2036 It is important to understand that the <tt>DEB_*_ARCH</tt>
2037 string only determines which Debian architecture we are
2038 building on or for. It should not be used to get the CPU
2039 or system information; the <tt>DEB_*_ARCH_CPU</tt> and
2040 <tt>DEB_*_ARCH_OS</tt> variables should be used for that.
2041 GNU style variables should generally only be used with upstream
2045 <sect1 id="debianrules-options">
2046 <heading><file>debian/rules</file> and
2047 <tt>DEB_BUILD_OPTIONS</tt></heading>
2050 Supporting the standardized environment variable
2051 <tt>DEB_BUILD_OPTIONS</tt> is recommended. This variable can
2052 contain several flags to change how a package is compiled and
2053 built. Each flag must be in the form <var>flag</var> or
2054 <var>flag</var>=<var>options</var>. If multiple flags are
2055 given, they must be separated by whitespace.<footnote>
2056 Some packages support any delimiter, but whitespace is the
2057 easiest to parse inside a makefile and avoids ambiguity with
2058 flag values that contain commas.
2060 <var>flag</var> must start with a lowercase letter
2061 (<tt>a-z</tt>) and consist only of lowercase letters,
2062 numbers (<tt>0-9</tt>), and the characters
2063 <tt>-</tt> and <tt>_</tt> (hyphen and underscore).
2064 <var>options</var> must not contain whitespace. The same
2065 tag should not be given multiple times with conflicting
2066 values. Package maintainers may assume that
2067 <tt>DEB_BUILD_OPTIONS</tt> will not contain conflicting tags.
2071 The meaning of the following tags has been standardized:
2075 This tag says to not run any build-time test suite
2076 provided by the package.
2080 The presence of this tag means that the package should
2081 be compiled with a minimum of optimization. For C
2082 programs, it is best to add <tt>-O0</tt> to
2083 <tt>CFLAGS</tt> (although this is usually the default).
2084 Some programs might fail to build or run at this level
2085 of optimization; it may be necessary to use
2086 <tt>-O1</tt>, for example.
2090 This tag means that the debugging symbols should not be
2091 stripped from the binary during installation, so that
2092 debugging information may be included in the package.
2094 <tag>parallel=n</tag>
2096 This tag means that the package should be built using up
2097 to <tt>n</tt> parallel processes if the package build
2098 system supports this.<footnote>
2099 Packages built with <tt>make</tt> can often implement
2100 this by passing the <tt>-j</tt><var>n</var> option to
2103 If the package build system does not support parallel
2104 builds, this string must be ignored. If the package
2105 build system only supports a lower level of concurrency
2106 than <var>n</var>, the package should be built using as
2107 many parallel processes as the package build system
2108 supports. It is up to the package maintainer to decide
2109 whether the package build times are long enough and the
2110 package build system is robust enough to make supporting
2111 parallel builds worthwhile.
2117 Unknown flags must be ignored by <file>debian/rules</file>.
2121 The following makefile snippet is an example of how one may
2122 implement the build options; you will probably have to
2123 massage this example in order to make it work for your
2125 <example compact="compact">
2128 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
2129 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
2130 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
2131 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
2133 ifneq (,$(filter noopt,$(DEB_BUILD_OPTIONS)))
2138 ifeq (,$(filter nostrip,$(DEB_BUILD_OPTIONS)))
2139 INSTALL_PROGRAM += -s
2141 ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2142 NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2143 MAKEFLAGS += -j$(NUMJOBS)
2148 ifeq (,$(filter nocheck,$(DEB_BUILD_OPTIONS)))
2149 # Code to run the package test suite.
2156 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2157 <sect id="substvars">
2158 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2161 When <prgn>dpkg-gencontrol</prgn>,
2162 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2163 generate control files they perform variable substitutions
2164 on their output just before writing it. Variable
2165 substitutions have the form <tt>${<var>variable</var>}</tt>.
2166 The optional file <file>debian/substvars</file> contains
2167 variable substitutions to be used; variables can also be set
2168 directly from <file>debian/rules</file> using the <tt>-V</tt>
2169 option to the source packaging commands, and certain
2170 predefined variables are also available.
2174 The <file>debian/substvars</file> file is usually generated and
2175 modified dynamically by <file>debian/rules</file> targets, in
2176 which case it must be removed by the <tt>clean</tt> target.
2180 See <manref name="deb-substvars" section="5"> for full
2181 details about source variable substitutions, including the
2182 format of <file>debian/substvars</file>.</p>
2185 <sect id="debianwatch">
2186 <heading>Optional upstream source location: <file>debian/watch</file></heading>
2189 This is an optional, recommended control file for the
2190 <tt>uscan</tt> utility which defines how to automatically
2191 scan ftp or http sites for newly available updates of the
2192 package. This is used by <url id="
2193 http://dehs.alioth.debian.org/"> and other Debian QA tools
2194 to help with quality control and maintenance of the
2195 distribution as a whole.
2200 <sect id="debianfiles">
2201 <heading>Generated files list: <file>debian/files</file></heading>
2204 This file is not a permanent part of the source tree; it
2205 is used while building packages to record which files are
2206 being generated. <prgn>dpkg-genchanges</prgn> uses it
2207 when it generates a <file>.changes</file> file.
2211 It should not exist in a shipped source package, and so it
2212 (and any backup files or temporary files such as
2213 <file>files.new</file><footnote>
2214 <file>files.new</file> is used as a temporary file by
2215 <prgn>dpkg-gencontrol</prgn> and
2216 <prgn>dpkg-distaddfile</prgn> - they write a new
2217 version of <tt>files</tt> here before renaming it,
2218 to avoid leaving a corrupted copy if an error
2220 </footnote>) should be removed by the
2221 <tt>clean</tt> target. It may also be wise to
2222 ensure a fresh start by emptying or removing it at the
2223 start of the <tt>binary</tt> target.
2227 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2228 package, it adds an entry to <file>debian/files</file> for the
2229 <file>.deb</file> file that will be created when <tt>dpkg-deb
2230 --build</tt> is run for that binary package. So for most
2231 packages all that needs to be done with this file is to
2232 delete it in the <tt>clean</tt> target.
2236 If a package upload includes files besides the source
2237 package and any binary packages whose control files were
2238 made with <prgn>dpkg-gencontrol</prgn> then they should be
2239 placed in the parent of the package's top-level directory
2240 and <prgn>dpkg-distaddfile</prgn> should be called to add
2241 the file to the list in <file>debian/files</file>.</p>
2244 <sect id="embeddedfiles">
2245 <heading>Convenience copies of code</heading>
2248 Some software packages include in their distribution convenience
2249 copies of code from other software packages, generally so that
2250 users compiling from source don't have to download multiple
2251 packages. Debian packages should not make use of these
2252 convenience copies unless the included package is explicitly
2253 intended to be used in this way.<footnote>
2254 For example, parts of the GNU build system work like this.
2256 If the included code is already in the Debian archive in the
2257 form of a library, the Debian packaging should ensure that
2258 binary packages reference the libraries already in Debian and
2259 the convenience copy is not used. If the included code is not
2260 already in Debian, it should be packaged separately as a
2261 prerequisite if possible.
2263 Having multiple copies of the same code in Debian is
2264 inefficient, often creates either static linking or shared
2265 library conflicts, and, most importantly, increases the
2266 difficulty of handling security vulnerabilities in the
2272 <sect id="readmesource">
2273 <heading>Source package handling:
2274 <file>debian/README.source</file></heading>
2277 If running <prgn>dpkg-source -x</prgn> on a source package
2278 doesn't produce the source of the package, ready for editing,
2279 and allow one to make changes and run
2280 <prgn>dpkg-buildpackage</prgn> to produce a modified package
2281 without taking any additional steps, creating a
2282 <file>debian/README.source</file> documentation file is
2283 recommended. This file should explain how to do all of the
2286 <item>Generate the fully patched source, in a form ready for
2287 editing, that would be built to create Debian
2288 packages. Doing this with a <tt>patch</tt> target in
2289 <file>debian/rules</file> is recommended; see
2290 <ref id="debianrules">.</item>
2291 <item>Modify the source and save those modifications so that
2292 they will be applied when building the package.</item>
2293 <item>Remove source modifications that are currently being
2294 applied when building the package.</item>
2295 <item>Optionally, document what steps are necessary to
2296 upgrade the Debian source package to a new upstream version,
2297 if applicable.</item>
2299 This explanation should include specific commands and mention
2300 any additional required Debian packages. It should not assume
2301 familiarity with any specific Debian packaging system or patch
2306 This explanation may refer to a documentation file installed by
2307 one of the package's build dependencies provided that the
2308 referenced documentation clearly explains these tasks and is not
2309 a general reference manual.
2313 <file>debian/README.source</file> may also include any other
2314 information that would be helpful to someone modifying the
2315 source package. Even if the package doesn't fit the above
2316 description, maintainers are encouraged to document in a
2317 <file>debian/README.source</file> file any source package with a
2318 particularly complex or unintuitive source layout or build
2319 system (for example, a package that builds the same source
2320 multiple times to generate different binary packages).
2326 <chapt id="controlfields">
2327 <heading>Control files and their fields</heading>
2330 The package management system manipulates data represented in
2331 a common format, known as <em>control data</em>, stored in
2332 <em>control files</em>.
2333 Control files are used for source packages, binary packages and
2334 the <file>.changes</file> files which control the installation
2335 of uploaded files<footnote>
2336 <prgn>dpkg</prgn>'s internal databases are in a similar
2341 <sect id="controlsyntax">
2342 <heading>Syntax of control files</heading>
2345 A control file consists of one or more paragraphs of
2347 The paragraphs are also sometimes referred to as stanzas.
2349 The paragraphs are separated by blank lines. Some control
2350 files allow only one paragraph; others allow several, in
2351 which case each paragraph usually refers to a different
2352 package. (For example, in source packages, the first
2353 paragraph refers to the source package, and later paragraphs
2354 refer to binary packages generated from the source.)
2358 Each paragraph consists of a series of data fields; each
2359 field consists of the field name, followed by a colon and
2360 then the data/value associated with that field. It ends at
2361 the end of the (logical) line. Horizontal whitespace
2362 (spaces and tabs) may occur immediately before or after the
2363 value and is ignored there; it is conventional to put a
2364 single space after the colon. For example, a field might
2366 <example compact="compact">
2369 the field name is <tt>Package</tt> and the field value
2374 Many fields' values may span several lines; in this case
2375 each continuation line must start with a space or a tab.
2376 Any trailing spaces or tabs at the end of individual
2377 lines of a field value are ignored.
2381 In fields where it is specified that lines may not wrap,
2382 only a single line of data is allowed and whitespace is not
2383 significant in a field body. Whitespace must not appear
2384 inside names (of packages, architectures, files or anything
2385 else) or version numbers, or between the characters of
2386 multi-character version relationships.
2390 Field names are not case-sensitive, but it is usual to
2391 capitalize the field names using mixed case as shown below.
2392 Field values are case-sensitive unless the description of the
2393 field says otherwise.
2397 Blank lines, or lines consisting only of spaces and tabs,
2398 are not allowed within field values or between fields - that
2399 would mean a new paragraph.
2403 All control files must be encoded in UTF-8.
2407 <sect id="sourcecontrolfiles">
2408 <heading>Source package control files -- <file>debian/control</file></heading>
2411 The <file>debian/control</file> file contains the most vital
2412 (and version-independent) information about the source package
2413 and about the binary packages it creates.
2417 The first paragraph of the control file contains information about
2418 the source package in general. The subsequent sets each describe a
2419 binary package that the source tree builds.
2423 The fields in the general paragraph (the first one, for the source
2426 <list compact="compact">
2427 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2428 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2429 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2430 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2431 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2432 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2433 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2434 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2439 The fields in the binary package paragraphs are:
2441 <list compact="compact">
2442 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2443 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2444 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2445 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2446 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2447 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2448 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2449 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2454 The syntax and semantics of the fields are described below.
2460 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2461 generate control files for binary packages (see below), by
2462 <prgn>dpkg-genchanges</prgn> to generate the
2463 <tt>.changes</tt> file to accompany the upload, and by
2464 <prgn>dpkg-source</prgn> when it creates the
2465 <file>.dsc</file> source control file as part of a source
2466 archive. Many fields are permitted to span multiple lines in
2467 <file>debian/control</file> but not in any other control
2468 file. These tools are responsible for removing the line
2469 breaks from such fields when using fields from
2470 <file>debian/control</file> to generate other control files.
2474 The fields here may contain variable references - their
2475 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2476 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2477 when they generate output control files.
2478 See <ref id="substvars"> for details.
2482 In addition to the control file syntax described <qref
2483 id="controlsyntax">above</qref>, this file may also contain
2484 comment lines starting with <tt>#</tt> without any preceding
2485 whitespace. All such lines are ignored, even in the middle of
2486 continuation lines for a multiline field, and do not end a
2492 <sect id="binarycontrolfiles">
2493 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2496 The <file>DEBIAN/control</file> file contains the most vital
2497 (and version-dependent) information about a binary package.
2501 The fields in this file are:
2503 <list compact="compact">
2504 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2505 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2506 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2507 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2508 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2509 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2510 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2511 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2512 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2513 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2514 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2515 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2520 <sect id="debiansourcecontrolfiles">
2521 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2524 This file contains a series of fields, identified and
2525 separated just like the fields in the control file of
2526 a binary package. The fields are listed below; their
2527 syntax is described above, in <ref id="pkg-controlfields">.
2529 <list compact="compact">
2530 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2531 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2532 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2533 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2534 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2535 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2536 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2537 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2538 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2539 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2540 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2545 The source package control file is generated by
2546 <prgn>dpkg-source</prgn> when it builds the source
2547 archive, from other files in the source package,
2548 described above. When unpacking, it is checked against
2549 the files and directories in the other parts of the
2555 <sect id="debianchangesfiles">
2556 <heading>Debian changes files -- <file>.changes</file></heading>
2559 The .changes files are used by the Debian archive maintenance
2560 software to process updates to packages. They contain one
2561 paragraph which contains information from the
2562 <tt>debian/control</tt> file and other data about the
2563 source package gathered via <tt>debian/changelog</tt>
2564 and <tt>debian/rules</tt>.
2568 The fields in this file are:
2570 <list compact="compact">
2571 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2572 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2573 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2574 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2575 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2576 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2577 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2578 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2579 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2580 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2581 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2582 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2583 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2584 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2589 <sect id="controlfieldslist">
2590 <heading>List of fields</heading>
2592 <sect1 id="f-Source">
2593 <heading><tt>Source</tt></heading>
2596 This field identifies the source package name.
2600 In <file>debian/control</file> or a <file>.dsc</file> file,
2601 this field must contain only the name of the source package.
2605 In a binary package control file or a <file>.changes</file>
2606 file, the source package name may be followed by a version
2607 number in parentheses<footnote>
2608 It is customary to leave a space after the package name
2609 if a version number is specified.
2611 This version number may be omitted (and is, by
2612 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2613 the <tt>Version</tt> field of the binary package in
2614 question. The field itself may be omitted from a binary
2615 package control file when the source package has the same
2616 name and version as the binary package.
2620 Package names (both source and binary,
2621 see <ref id="f-Package">) must consist only of lower case
2622 letters (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus
2623 (<tt>+</tt>) and minus (<tt>-</tt>) signs, and periods
2624 (<tt>.</tt>). They must be at least two characters long and
2625 must start with an alphanumeric character.
2629 <sect1 id="f-Maintainer">
2630 <heading><tt>Maintainer</tt></heading>
2633 The package maintainer's name and email address. The name
2634 should come first, then the email address inside angle
2635 brackets <tt><></tt> (in RFC822 format).
2639 If the maintainer's name contains a full stop then the
2640 whole field will not work directly as an email address due
2641 to a misfeature in the syntax specified in RFC822; a
2642 program using this field as an address must check for this
2643 and correct the problem if necessary (for example by
2644 putting the name in round brackets and moving it to the
2645 end, and bringing the email address forward).
2649 <sect1 id="f-Uploaders">
2650 <heading><tt>Uploaders</tt></heading>
2653 List of the names and email addresses of co-maintainers of
2654 the package, if any. If the package has other maintainers
2655 beside the one named in the
2656 <qref id="f-Maintainer">Maintainer field</qref>, their
2657 names and email addresses should be listed here. The
2658 format is the same as that of the Maintainer tag, and
2659 multiple entries should be comma separated. Currently,
2660 this field is restricted to a single line of data. This
2661 is an optional field.
2664 Any parser that interprets the Uploaders field in
2665 <file>debian/control</file> must permit it to span multiple
2666 lines. Line breaks in an Uploaders field that spans multiple
2667 lines are not significant and the semantics of the field are
2668 the same as if the line breaks had not been present.
2672 <sect1 id="f-Changed-By">
2673 <heading><tt>Changed-By</tt></heading>
2676 The name and email address of the person who changed the
2677 said package. Usually the name of the maintainer.
2678 All the rules for the Maintainer field apply here, too.
2682 <sect1 id="f-Section">
2683 <heading><tt>Section</tt></heading>
2686 This field specifies an application area into which the package
2687 has been classified. See <ref id="subsections">.
2691 When it appears in the <file>debian/control</file> file,
2692 it gives the value for the subfield of the same name in
2693 the <tt>Files</tt> field of the <file>.changes</file> file.
2694 It also gives the default for the same field in the binary
2699 <sect1 id="f-Priority">
2700 <heading><tt>Priority</tt></heading>
2703 This field represents how important it is that the user
2704 have the package installed. See <ref id="priorities">.
2708 When it appears in the <file>debian/control</file> file,
2709 it gives the value for the subfield of the same name in
2710 the <tt>Files</tt> field of the <file>.changes</file> file.
2711 It also gives the default for the same field in the binary
2716 <sect1 id="f-Package">
2717 <heading><tt>Package</tt></heading>
2720 The name of the binary package.
2724 Binary package names must follow the same syntax and
2725 restrictions as source package names. See <ref id="f-Source">
2730 <sect1 id="f-Architecture">
2731 <heading><tt>Architecture</tt></heading>
2734 Depending on context and the control file used, the
2735 <tt>Architecture</tt> field can include the following sets of
2739 A unique single word identifying a Debian machine
2740 architecture as described in <ref id="arch-spec">.
2743 An architecture wildcard identifying a set of Debian
2744 machine architectures, see <ref id="arch-wildcard-spec">.
2745 <tt>any</tt> matches all Debian machine architectures
2746 and is the most frequently used.
2749 <tt>all</tt>, which indicates an
2750 architecture-independent package.
2753 <tt>source</tt>, which indicates a source package.
2759 In the main <file>debian/control</file> file in the source
2760 package, this field may contain the special value <tt>all</tt>
2761 or a list of specific and wildcard architectures separated by
2762 spaces. If <tt>all</tt> appears, that value must be the
2763 entire contents of the field. Most packages will use
2764 either <tt>any</tt> or <tt>all</tt>.
2768 Specifying a specific list of architectures indicates that the
2769 source will build an architecture-dependent package only on
2770 architectures included in the list. Specifying a list of
2771 architecture wildcards indicates that the source will build an
2772 architecture-dependent package on only those architectures
2773 that match any of the specified architecture wildcards.
2774 Specifying a list of architectures or architecture wildcards
2775 other than <tt>any</tt> is for the minority of cases where a
2776 program is not portable or is not useful on some
2777 architectures. Where possible, the program should be made
2782 In the source package control file <file>.dsc</file>, this
2783 field may contain either the architecture
2784 wildcard <tt>any</tt> or a list of architectures and
2785 architecture wildcards separated by spaces. If a list is
2786 given, it may include (or consist solely of) the special
2787 value <tt>all</tt>. In other words, in <file>.dsc</file>
2788 files unlike the <file>debian/control</file>, <tt>all</tt> may
2789 occur in combination with specific architectures.
2790 The <tt>Architecture</tt> field in the source package control
2791 file <file>.dsc</file> is generally constructed from
2792 the <tt>Architecture</tt> fields in
2793 the <file>debian/control</file> in the source package.
2797 Specifying <tt>any</tt> indicates that the source package
2798 isn't dependent on any particular architecture and should
2799 compile fine on any one. The produced binary package(s)
2800 will either be specific to whatever the current build
2801 architecture is or will be architecture-independent.
2805 Specifying only <tt>all</tt> indicates that the source package
2806 will only build architecture-independent packages. If this is
2807 the case, <tt>all</tt> must be used rather than <tt>any</tt>;
2808 <tt>any</tt> implies that the source package will build at
2809 least one architecture-dependent package.
2813 Specifying a list of architectures or architecture wildcards
2814 indicates that the source will build an architecture-dependent
2815 package, and will only work correctly on the listed or
2816 matching architectures. If the source package also builds at
2817 least one architecture-independent package, <tt>all</tt> will
2818 also be included in the list.
2822 In a <file>.changes</file> file, the <tt>Architecture</tt>
2823 field lists the architecture(s) of the package(s) currently
2824 being uploaded. This will be a list; if the source for the
2825 package is also being uploaded, the special
2826 entry <tt>source</tt> is also present. <tt>all</tt> will be
2827 present if any architecture-independent packages are being
2828 uploaded. Architecture wildcards such as <tt>any</tt> must
2829 never occur in the <tt>Architecture</tt> field in
2830 the <file>.changes</file> file.
2834 See <ref id="debianrules"> for information on how to get
2835 the architecture for the build process.
2839 <sect1 id="f-Essential">
2840 <heading><tt>Essential</tt></heading>
2843 This is a boolean field which may occur only in the
2844 control file of a binary package or in a per-package fields
2845 paragraph of a main source control data file.
2849 If set to <tt>yes</tt> then the package management system
2850 will refuse to remove the package (upgrading and replacing
2851 it is still possible). The other possible value is <tt>no</tt>,
2852 which is the same as not having the field at all.
2857 <heading>Package interrelationship fields:
2858 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2859 <tt>Recommends</tt>, <tt>Suggests</tt>,
2860 <tt>Breaks</tt>, <tt>Conflicts</tt>,
2861 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2865 These fields describe the package's relationships with
2866 other packages. Their syntax and semantics are described
2867 in <ref id="relationships">.</p>
2870 <sect1 id="f-Standards-Version">
2871 <heading><tt>Standards-Version</tt></heading>
2874 The most recent version of the standards (the policy
2875 manual and associated texts) with which the package
2880 The version number has four components: major and minor
2881 version number and major and minor patch level. When the
2882 standards change in a way that requires every package to
2883 change the major number will be changed. Significant
2884 changes that will require work in many packages will be
2885 signaled by a change to the minor number. The major patch
2886 level will be changed for any change to the meaning of the
2887 standards, however small; the minor patch level will be
2888 changed when only cosmetic, typographical or other edits
2889 are made which neither change the meaning of the document
2890 nor affect the contents of packages.
2894 Thus only the first three components of the policy version
2895 are significant in the <em>Standards-Version</em> control
2896 field, and so either these three components or all four
2897 components may be specified.<footnote>
2898 In the past, people specified the full version number
2899 in the Standards-Version field, for example "2.3.0.0".
2900 Since minor patch-level changes don't introduce new
2901 policy, it was thought it would be better to relax
2902 policy and only require the first 3 components to be
2903 specified, in this example "2.3.0". All four
2904 components may still be used if someone wishes to do so.
2910 <sect1 id="f-Version">
2911 <heading><tt>Version</tt></heading>
2914 The version number of a package. The format is:
2915 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2919 The three components here are:
2921 <tag><var>epoch</var></tag>
2924 This is a single (generally small) unsigned integer. It
2925 may be omitted, in which case zero is assumed. If it is
2926 omitted then the <var>upstream_version</var> may not
2931 It is provided to allow mistakes in the version numbers
2932 of older versions of a package, and also a package's
2933 previous version numbering schemes, to be left behind.
2937 <tag><var>upstream_version</var></tag>
2940 This is the main part of the version number. It is
2941 usually the version number of the original ("upstream")
2942 package from which the <file>.deb</file> file has been made,
2943 if this is applicable. Usually this will be in the same
2944 format as that specified by the upstream author(s);
2945 however, it may need to be reformatted to fit into the
2946 package management system's format and comparison
2951 The comparison behavior of the package management system
2952 with respect to the <var>upstream_version</var> is
2953 described below. The <var>upstream_version</var>
2954 portion of the version number is mandatory.
2958 The <var>upstream_version</var> may contain only
2959 alphanumerics<footnote>
2960 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2962 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2963 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
2964 tilde) and should start with a digit. If there is no
2965 <var>debian_revision</var> then hyphens are not allowed;
2966 if there is no <var>epoch</var> then colons are not
2971 <tag><var>debian_revision</var></tag>
2974 This part of the version number specifies the version of
2975 the Debian package based on the upstream version. It
2976 may contain only alphanumerics and the characters
2977 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
2978 tilde) and is compared in the same way as the
2979 <var>upstream_version</var> is.
2983 It is optional; if it isn't present then the
2984 <var>upstream_version</var> may not contain a hyphen.
2985 This format represents the case where a piece of
2986 software was written specifically to be turned into a
2987 Debian package, and so there is only one "debianisation"
2988 of it and therefore no revision indication is required.
2992 It is conventional to restart the
2993 <var>debian_revision</var> at <tt>1</tt> each time the
2994 <var>upstream_version</var> is increased.
2998 The package management system will break the version
2999 number apart at the last hyphen in the string (if there
3000 is one) to determine the <var>upstream_version</var> and
3001 <var>debian_revision</var>. The absence of a
3002 <var>debian_revision</var> is equivalent to a
3003 <var>debian_revision</var> of <tt>0</tt>.
3010 When comparing two version numbers, first the <var>epoch</var>
3011 of each are compared, then the <var>upstream_version</var> if
3012 <var>epoch</var> is equal, and then <var>debian_revision</var>
3013 if <var>upstream_version</var> is also equal.
3014 <var>epoch</var> is compared numerically. The
3015 <var>upstream_version</var> and <var>debian_revision</var>
3016 parts are compared by the package management system using the
3017 following algorithm:
3021 The strings are compared from left to right.
3025 First the initial part of each string consisting entirely of
3026 non-digit characters is determined. These two parts (one of
3027 which may be empty) are compared lexically. If a difference
3028 is found it is returned. The lexical comparison is a
3029 comparison of ASCII values modified so that all the letters
3030 sort earlier than all the non-letters and so that a tilde
3031 sorts before anything, even the end of a part. For example,
3032 the following parts are in sorted order from earliest to
3033 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
3034 <tt>a</tt>.<footnote>
3035 One common use of <tt>~</tt> is for upstream pre-releases.
3036 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
3037 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
3042 Then the initial part of the remainder of each string which
3043 consists entirely of digit characters is determined. The
3044 numerical values of these two parts are compared, and any
3045 difference found is returned as the result of the comparison.
3046 For these purposes an empty string (which can only occur at
3047 the end of one or both version strings being compared) counts
3052 These two steps (comparing and removing initial non-digit
3053 strings and initial digit strings) are repeated until a
3054 difference is found or both strings are exhausted.
3058 Note that the purpose of epochs is to allow us to leave behind
3059 mistakes in version numbering, and to cope with situations
3060 where the version numbering scheme changes. It is
3061 <em>not</em> intended to cope with version numbers containing
3062 strings of letters which the package management system cannot
3063 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
3064 silly orderings (the author of this manual has heard of a
3065 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
3066 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
3067 <tt>2</tt> and so forth).
3071 <sect1 id="f-Description">
3072 <heading><tt>Description</tt></heading>
3075 In a source or binary control file, the <tt>Description</tt>
3076 field contains a description of the binary package, consisting
3077 of two parts, the synopsis or the short description, and the
3078 long description. The field's format is as follows:
3083 Description: <single line synopsis>
3084 <extended description over several lines>
3089 The lines in the extended description can have these formats:
3095 Those starting with a single space are part of a paragraph.
3096 Successive lines of this form will be word-wrapped when
3097 displayed. The leading space will usually be stripped off.
3101 Those starting with two or more spaces. These will be
3102 displayed verbatim. If the display cannot be panned
3103 horizontally, the displaying program will line wrap them "hard"
3104 (i.e., without taking account of word breaks). If it can they
3105 will be allowed to trail off to the right. None, one or two
3106 initial spaces may be deleted, but the number of spaces
3107 deleted from each line will be the same (so that you can have
3108 indenting work correctly, for example).
3112 Those containing a single space followed by a single full stop
3113 character. These are rendered as blank lines. This is the
3114 <em>only</em> way to get a blank line<footnote>
3115 Completely empty lines will not be rendered as blank lines.
3116 Instead, they will cause the parser to think you're starting
3117 a whole new record in the control file, and will therefore
3118 likely abort with an error.
3123 Those containing a space, a full stop and some more characters.
3124 These are for future expansion. Do not use them.
3130 Do not use tab characters. Their effect is not predictable.
3134 See <ref id="descriptions"> for further information on this.
3138 In a <file>.changes</file> file, the <tt>Description</tt>
3139 field contains a summary of the descriptions for the packages
3140 being uploaded. For this case, the first line of the field
3141 value (the part on the same line as <tt>Description:</tt>) is
3142 always empty. The content of the field is expressed as
3143 continuation lines, one line per package. Each line is
3144 indented by one space and contains the name of a binary
3145 package, a space, a hyphen (<tt>-</tt>), a space, and the
3146 short description line from that package.
3150 <sect1 id="f-Distribution">
3151 <heading><tt>Distribution</tt></heading>
3154 In a <file>.changes</file> file or parsed changelog output
3155 this contains the (space-separated) name(s) of the
3156 distribution(s) where this version of the package should
3157 be installed. Valid distributions are determined by the
3158 archive maintainers.<footnote>
3159 Example distribution names in the Debian archive used in
3160 <file>.changes</file> files are:
3161 <taglist compact="compact">
3162 <tag><em>unstable</em></tag>
3164 This distribution value refers to the
3165 <em>developmental</em> part of the Debian distribution
3166 tree. Most new packages, new upstream versions of
3167 packages and bug fixes go into the <em>unstable</em>
3171 <tag><em>experimental</em></tag>
3173 The packages with this distribution value are deemed
3174 by their maintainers to be high risk. Oftentimes they
3175 represent early beta or developmental packages from
3176 various sources that the maintainers want people to
3177 try, but are not ready to be a part of the other parts
3178 of the Debian distribution tree.
3183 Others are used for updating stable releases or for
3184 security uploads. More information is available in the
3185 Debian Developer's Reference, section "The Debian
3189 The Debian archive software only supports listing a single
3190 distribution. Migration of packages to other distributions is
3191 handled outside of the upload process.
3196 <heading><tt>Date</tt></heading>
3199 This field includes the date the package was built or last edited.
3203 The value of this field is usually extracted from the
3204 <file>debian/changelog</file> file - see
3205 <ref id="dpkgchangelog">).
3209 <sect1 id="f-Format">
3210 <heading><tt>Format</tt></heading>
3213 This field specifies a format revision for the file.
3214 The most current format described in the Policy Manual
3215 is version <strong>1.5</strong>. The syntax of the
3216 format value is the same as that of a package version
3217 number except that no epoch or Debian revision is allowed
3218 - see <ref id="f-Version">.
3222 <sect1 id="f-Urgency">
3223 <heading><tt>Urgency</tt></heading>
3226 This is a description of how important it is to upgrade to
3227 this version from previous ones. It consists of a single
3228 keyword taking one of the values <tt>low</tt>,
3229 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3230 <tt>critical</tt><footnote>
3231 Other urgency values are supported with configuration
3232 changes in the archive software but are not used in Debian.
3233 The urgency affects how quickly a package will be considered
3234 for inclusion into the <tt>testing</tt> distribution and
3235 gives an indication of the importance of any fixes included
3236 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3237 treated as synonymous.
3238 </footnote> (not case-sensitive) followed by an optional
3239 commentary (separated by a space) which is usually in
3240 parentheses. For example:
3243 Urgency: low (HIGH for users of diversions)
3249 The value of this field is usually extracted from the
3250 <file>debian/changelog</file> file - see
3251 <ref id="dpkgchangelog">.
3255 <sect1 id="f-Changes">
3256 <heading><tt>Changes</tt></heading>
3259 This field contains the human-readable changes data, describing
3260 the differences between the last version and the current one.
3264 The first line of the field value (the part on the same line
3265 as <tt>Changes:</tt>) is always empty. The content of the
3266 field is expressed as continuation lines, with each line
3267 indented by at least one space. Blank lines must be
3268 represented by a line consisting only of a space and a full
3273 The value of this field is usually extracted from the
3274 <file>debian/changelog</file> file - see
3275 <ref id="dpkgchangelog">).
3279 Each version's change information should be preceded by a
3280 "title" line giving at least the version, distribution(s)
3281 and urgency, in a human-readable way.
3285 If data from several versions is being returned the entry
3286 for the most recent version should be returned first, and
3287 entries should be separated by the representation of a
3288 blank line (the "title" line may also be followed by the
3289 representation of a blank line).
3293 <sect1 id="f-Binary">
3294 <heading><tt>Binary</tt></heading>
3297 This field is a list of binary packages. Its syntax and
3298 meaning varies depending on the control file in which it
3303 When it appears in the <file>.dsc</file> file, it lists binary
3304 packages which a source package can produce, separated by
3306 A space after each comma is conventional.
3307 </footnote>. It may span multiple lines. The source package
3308 does not necessarily produce all of these binary packages for
3309 every architecture. The source control file doesn't contain
3310 details of which architectures are appropriate for which of
3311 the binary packages.
3315 When it appears in a <file>.changes</file> file, it lists the
3316 names of the binary packages being uploaded, separated by
3317 whitespace (not commas). It may span multiple lines.
3321 <sect1 id="f-Installed-Size">
3322 <heading><tt>Installed-Size</tt></heading>
3325 This field appears in the control files of binary packages,
3326 and in the <file>Packages</file> files. It gives an estimate
3327 of the total amount of disk space required to install the
3328 named package. Actual installed size may vary based on block
3329 size, file system properties, or actions taken by package
3334 The disk space is given as the integer value of the estimated
3335 installed size in bytes, divided by 1024 and rounded up.
3339 <sect1 id="f-Files">
3340 <heading><tt>Files</tt></heading>
3343 This field contains a list of files with information about
3344 each one. The exact information and syntax varies with
3349 In all cases, Files is a multiline field. The first line of
3350 the field value (the part on the same line as <tt>Files:</tt>)
3351 is always empty. The content of the field is expressed as
3352 continuation lines, one line per file. Each line must be
3353 indented by one space and contain a number of sub-fields,
3354 separated by spaces, as described below.
3358 In the <file>.dsc</file> file, each line contains the MD5
3359 checksum, size and filename of the tar file and (if
3360 applicable) diff file which make up the remainder of the
3361 source package<footnote>
3362 That is, the parts which are not the <tt>.dsc</tt>.
3363 </footnote>. For example:
3366 c6f698f19f2a2aa07dbb9bbda90a2754 571925 example_1.2.orig.tar.gz
3367 938512f08422f3509ff36f125f5873ba 6220 example_1.2-1.diff.gz
3369 The exact forms of the filenames are described
3370 in <ref id="pkg-sourcearchives">.
3374 In the <file>.changes</file> file this contains one line per
3375 file being uploaded. Each line contains the MD5 checksum,
3376 size, section and priority and the filename. For example:
3379 4c31ab7bfc40d3cf49d7811987390357 1428 text extra example_1.2-1.dsc
3380 c6f698f19f2a2aa07dbb9bbda90a2754 571925 text extra example_1.2.orig.tar.gz
3381 938512f08422f3509ff36f125f5873ba 6220 text extra example_1.2-1.diff.gz
3382 7c98fe853b3bbb47a00e5cd129b6cb56 703542 text extra example_1.2-1_i386.deb
3384 The <qref id="f-Section">section</qref>
3385 and <qref id="f-Priority">priority</qref> are the values of
3386 the corresponding fields in the main source control file. If
3387 no section or priority is specified then <tt>-</tt> should be
3388 used, though section and priority values must be specified for
3389 new packages to be installed properly.
3393 The special value <tt>byhand</tt> for the section in a
3394 <tt>.changes</tt> file indicates that the file in question
3395 is not an ordinary package file and must by installed by
3396 hand by the distribution maintainers. If the section is
3397 <tt>byhand</tt> the priority should be <tt>-</tt>.
3401 If a new Debian revision of a package is being shipped and
3402 no new original source archive is being distributed the
3403 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3404 entry for the original source archive
3405 <file><var>package</var>_<var>upstream-version</var>.orig.tar.gz</file>,
3406 but the <file>.changes</file> file should leave it out. In
3407 this case the original source archive on the distribution
3408 site must match exactly, byte-for-byte, the original
3409 source archive which was used to generate the
3410 <file>.dsc</file> file and diff which are being uploaded.</p>
3413 <sect1 id="f-Closes">
3414 <heading><tt>Closes</tt></heading>
3417 A space-separated list of bug report numbers that the upload
3418 governed by the .changes file closes.
3422 <sect1 id="f-Homepage">
3423 <heading><tt>Homepage</tt></heading>
3426 The URL of the web site for this package, preferably (when
3427 applicable) the site from which the original source can be
3428 obtained and any additional upstream documentation or
3429 information may be found. The content of this field is a
3430 simple URL without any surrounding characters such as
3438 <heading>User-defined fields</heading>
3441 Additional user-defined fields may be added to the
3442 source package control file. Such fields will be
3443 ignored, and not copied to (for example) binary or
3444 source package control files or upload control files.
3448 If you wish to add additional unsupported fields to
3449 these output files you should use the mechanism
3454 Fields in the main source control information file with
3455 names starting <tt>X</tt>, followed by one or more of
3456 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3457 be copied to the output files. Only the part of the
3458 field name after the hyphen will be used in the output
3459 file. Where the letter <tt>B</tt> is used the field
3460 will appear in binary package control files, where the
3461 letter <tt>S</tt> is used in source package control
3462 files and where <tt>C</tt> is used in upload control
3463 (<tt>.changes</tt>) files.
3467 For example, if the main source information control file
3470 XBS-Comment: I stand between the candle and the star.
3472 then the binary and source package control files will contain the
3475 Comment: I stand between the candle and the star.
3484 <chapt id="maintainerscripts">
3485 <heading>Package maintainer scripts and installation procedure</heading>
3488 <heading>Introduction to package maintainer scripts</heading>
3491 It is possible to supply scripts as part of a package which
3492 the package management system will run for you when your
3493 package is installed, upgraded or removed.
3497 These scripts are the files <prgn>preinst</prgn>,
3498 <prgn>postinst</prgn>, <prgn>prerm</prgn> and
3499 <prgn>postrm</prgn> in the control area of the package.
3500 They must be proper executable files; if they are scripts
3501 (which is recommended), they must start with the usual
3502 <tt>#!</tt> convention. They should be readable and
3503 executable by anyone, and must not be world-writable.
3507 The package management system looks at the exit status from
3508 these scripts. It is important that they exit with a
3509 non-zero status if there is an error, so that the package
3510 management system can stop its processing. For shell
3511 scripts this means that you <em>almost always</em> need to
3512 use <tt>set -e</tt> (this is usually true when writing shell
3513 scripts, in fact). It is also important, of course, that
3514 they exit with a zero status if everything went well.
3518 Additionally, packages interacting with users using
3519 <tt>debconf</tt> in the <prgn>postinst</prgn> script should
3520 install a <prgn>config</prgn> script in the control area,
3521 see <ref id="maintscriptprompt"> for details.
3525 When a package is upgraded a combination of the scripts from
3526 the old and new packages is called during the upgrade
3527 procedure. If your scripts are going to be at all
3528 complicated you need to be aware of this, and may need to
3529 check the arguments to your scripts.
3533 Broadly speaking the <prgn>preinst</prgn> is called before
3534 (a particular version of) a package is installed, and the
3535 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3536 before (a version of) a package is removed and the
3537 <prgn>postrm</prgn> afterwards.
3541 Programs called from maintainer scripts should not normally
3542 have a path prepended to them. Before installation is
3543 started, the package management system checks to see if the
3544 programs <prgn>ldconfig</prgn>,
3545 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3546 and <prgn>update-rc.d</prgn> can be found via the
3547 <tt>PATH</tt> environment variable. Those programs, and any
3548 other program that one would expect to be in the
3549 <tt>PATH</tt>, should thus be invoked without an absolute
3550 pathname. Maintainer scripts should also not reset the
3551 <tt>PATH</tt>, though they might choose to modify it by
3552 prepending or appending package-specific directories. These
3553 considerations really apply to all shell scripts.</p>
3556 <sect id="idempotency">
3557 <heading>Maintainer scripts idempotency</heading>
3560 It is necessary for the error recovery procedures that the
3561 scripts be idempotent. This means that if it is run
3562 successfully, and then it is called again, it doesn't bomb
3563 out or cause any harm, but just ensures that everything is
3564 the way it ought to be. If the first call failed, or
3565 aborted half way through for some reason, the second call
3566 should merely do the things that were left undone the first
3567 time, if any, and exit with a success status if everything
3569 This is so that if an error occurs, the user interrupts
3570 <prgn>dpkg</prgn> or some other unforeseen circumstance
3571 happens you don't leave the user with a badly-broken
3572 package when <prgn>dpkg</prgn> attempts to repeat the
3578 <sect id="controllingterminal">
3579 <heading>Controlling terminal for maintainer scripts</heading>
3582 The maintainer scripts are guaranteed to run with a
3583 controlling terminal and can interact with the user.
3584 Because these scripts may be executed with standard output
3585 redirected into a pipe for logging purposes, Perl scripts
3586 should set unbuffered output by setting <tt>$|=1</tt> so
3587 that the output is printed immediately rather than being
3591 <sect id="exitstatus">
3592 <heading>Exit status</heading>
3595 Each script must return a zero exit status for
3596 success, or a nonzero one for failure, since the package
3597 management system looks for the exit status of these scripts
3598 and determines what action to take next based on that datum.
3602 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3607 <list compact="compact">
3609 <var>new-preinst</var> <tt>install</tt>
3612 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3615 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3618 <var>old-preinst</var> <tt>abort-upgrade</tt>
3619 <var>new-version</var>
3624 <list compact="compact">
3626 <var>postinst</var> <tt>configure</tt>
3627 <var>most-recently-configured-version</var>
3630 <var>old-postinst</var> <tt>abort-upgrade</tt>
3631 <var>new-version</var>
3634 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3635 <tt>in-favour</tt> <var>package</var>
3636 <var>new-version</var>
3639 <var>postinst</var> <tt>abort-remove</tt>
3642 <var>deconfigured's-postinst</var>
3643 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3644 <var>failed-install-package</var> <var>version</var>
3645 [<tt>removing</tt> <var>conflicting-package</var>
3651 <list compact="compact">
3653 <var>prerm</var> <tt>remove</tt>
3656 <var>old-prerm</var> <tt>upgrade</tt>
3657 <var>new-version</var>
3660 <var>new-prerm</var> <tt>failed-upgrade</tt>
3661 <var>old-version</var>
3664 <var>conflictor's-prerm</var> <tt>remove</tt>
3665 <tt>in-favour</tt> <var>package</var>
3666 <var>new-version</var>
3669 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3670 <tt>in-favour</tt> <var>package-being-installed</var>
3671 <var>version</var> [<tt>removing</tt>
3672 <var>conflicting-package</var>
3678 <list compact="compact">
3680 <var>postrm</var> <tt>remove</tt>
3683 <var>postrm</var> <tt>purge</tt>
3686 <var>old-postrm</var> <tt>upgrade</tt>
3687 <var>new-version</var>
3690 <var>new-postrm</var> <tt>failed-upgrade</tt>
3691 <var>old-version</var>
3694 <var>new-postrm</var> <tt>abort-install</tt>
3697 <var>new-postrm</var> <tt>abort-install</tt>
3698 <var>old-version</var>
3701 <var>new-postrm</var> <tt>abort-upgrade</tt>
3702 <var>old-version</var>
3705 <var>disappearer's-postrm</var> <tt>disappear</tt>
3706 <var>overwriter</var>
3707 <var>overwriter-version</var>
3713 <sect id="unpackphase">
3714 <heading>Details of unpack phase of installation or upgrade</heading>
3717 The procedure on installation/upgrade/overwrite/disappear
3718 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3719 stage of <tt>dpkg --install</tt>) is as follows. In each
3720 case, if a major error occurs (unless listed below) the
3721 actions are, in general, run backwards - this means that the
3722 maintainer scripts are run with different arguments in
3723 reverse order. These are the "error unwind" calls listed
3730 If a version of the package is already installed, call
3731 <example compact="compact">
3732 <var>old-prerm</var> upgrade <var>new-version</var>
3736 If the script runs but exits with a non-zero
3737 exit status, <prgn>dpkg</prgn> will attempt:
3738 <example compact="compact">
3739 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3741 If this works, the upgrade continues. If this
3742 does not work, the error unwind:
3743 <example compact="compact">
3744 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3746 If this works, then the old-version is
3747 "Installed", if not, the old version is in a
3748 "Half-Configured" state.
3754 If a "conflicting" package is being removed at the same time,
3755 or if any package will be broken (due to <tt>Breaks</tt>):
3758 If <tt>--auto-deconfigure</tt> is
3759 specified, call, for each package to be deconfigured
3760 due to <tt>Breaks</tt>:
3761 <example compact="compact">
3762 <var>deconfigured's-prerm</var> deconfigure \
3763 in-favour <var>package-being-installed</var> <var>version</var>
3766 <example compact="compact">
3767 <var>deconfigured's-postinst</var> abort-deconfigure \
3768 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3770 The deconfigured packages are marked as
3771 requiring configuration, so that if
3772 <tt>--install</tt> is used they will be
3773 configured again if possible.
3776 If any packages depended on a conflicting
3777 package being removed and <tt>--auto-deconfigure</tt> is
3778 specified, call, for each such package:
3779 <example compact="compact">
3780 <var>deconfigured's-prerm</var> deconfigure \
3781 in-favour <var>package-being-installed</var> <var>version</var> \
3782 removing <var>conflicting-package</var> <var>version</var>
3785 <example compact="compact">
3786 <var>deconfigured's-postinst</var> abort-deconfigure \
3787 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3788 removing <var>conflicting-package</var> <var>version</var>
3790 The deconfigured packages are marked as
3791 requiring configuration, so that if
3792 <tt>--install</tt> is used they will be
3793 configured again if possible.
3796 To prepare for removal of each conflicting package, call:
3797 <example compact="compact">
3798 <var>conflictor's-prerm</var> remove \
3799 in-favour <var>package</var> <var>new-version</var>
3802 <example compact="compact">
3803 <var>conflictor's-postinst</var> abort-remove \
3804 in-favour <var>package</var> <var>new-version</var>
3813 If the package is being upgraded, call:
3814 <example compact="compact">
3815 <var>new-preinst</var> upgrade <var>old-version</var>
3817 If this fails, we call:
3819 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3826 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3828 is called. If this works, then the old version
3829 is in an "Installed" state, or else it is left
3830 in an "Unpacked" state.
3835 If it fails, then the old version is left
3836 in an "Half-Installed" state.
3843 Otherwise, if the package had some configuration
3844 files from a previous version installed (i.e., it
3845 is in the "configuration files only" state):
3846 <example compact="compact">
3847 <var>new-preinst</var> install <var>old-version</var>
3851 <var>new-postrm</var> abort-install <var>old-version</var>
3853 If this fails, the package is left in a
3854 "Half-Installed" state, which requires a
3855 reinstall. If it works, the packages is left in
3856 a "Config-Files" state.
3859 Otherwise (i.e., the package was completely purged):
3860 <example compact="compact">
3861 <var>new-preinst</var> install
3864 <example compact="compact">
3865 <var>new-postrm</var> abort-install
3867 If the error-unwind fails, the package is in a
3868 "Half-Installed" phase, and requires a
3869 reinstall. If the error unwind works, the
3870 package is in a not installed state.
3877 The new package's files are unpacked, overwriting any
3878 that may be on the system already, for example any
3879 from the old version of the same package or from
3880 another package. Backups of the old files are kept
3881 temporarily, and if anything goes wrong the package
3882 management system will attempt to put them back as
3883 part of the error unwind.
3887 It is an error for a package to contain files which
3888 are on the system in another package, unless
3889 <tt>Replaces</tt> is used (see <ref id="replaces">).
3891 The following paragraph is not currently the case:
3892 Currently the <tt>- - force-overwrite</tt> flag is
3893 enabled, downgrading it to a warning, but this may not
3899 It is a more serious error for a package to contain a
3900 plain file or other kind of non-directory where another
3901 package has a directory (again, unless
3902 <tt>Replaces</tt> is used). This error can be
3903 overridden if desired using
3904 <tt>--force-overwrite-dir</tt>, but this is not
3909 Packages which overwrite each other's files produce
3910 behavior which, though deterministic, is hard for the
3911 system administrator to understand. It can easily
3912 lead to "missing" programs if, for example, a package
3913 is installed which overwrites a file from another
3914 package, and is then removed again.<footnote>
3915 Part of the problem is due to what is arguably a
3916 bug in <prgn>dpkg</prgn>.
3921 A directory will never be replaced by a symbolic link
3922 to a directory or vice versa; instead, the existing
3923 state (symlink or not) will be left alone and
3924 <prgn>dpkg</prgn> will follow the symlink if there is
3933 If the package is being upgraded, call
3934 <example compact="compact">
3935 <var>old-postrm</var> upgrade <var>new-version</var>
3939 If this fails, <prgn>dpkg</prgn> will attempt:
3940 <example compact="compact">
3941 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3943 If this works, installation continues. If not,
3945 <example compact="compact">
3946 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3948 If this fails, the old version is left in a
3949 "Half-Installed" state. If it works, dpkg now
3951 <example compact="compact">
3952 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3954 If this fails, the old version is left in a
3955 "Half-Installed" state. If it works, dpkg now
3957 <example compact="compact">
3958 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3960 If this fails, the old version is in an
3967 This is the point of no return - if
3968 <prgn>dpkg</prgn> gets this far, it won't back off
3969 past this point if an error occurs. This will
3970 leave the package in a fairly bad state, which
3971 will require a successful re-installation to clear
3972 up, but it's when <prgn>dpkg</prgn> starts doing
3973 things that are irreversible.
3978 Any files which were in the old version of the package
3979 but not in the new are removed.
3983 The new file list replaces the old.
3987 The new maintainer scripts replace the old.
3991 Any packages all of whose files have been overwritten
3992 during the installation, and which aren't required for
3993 dependencies, are considered to have been removed.
3994 For each such package
3997 <prgn>dpkg</prgn> calls:
3998 <example compact="compact">
3999 <var>disappearer's-postrm</var> disappear \
4000 <var>overwriter</var> <var>overwriter-version</var>
4004 The package's maintainer scripts are removed.
4007 It is noted in the status database as being in a
4008 sane state, namely not installed (any conffiles
4009 it may have are ignored, rather than being
4010 removed by <prgn>dpkg</prgn>). Note that
4011 disappearing packages do not have their prerm
4012 called, because <prgn>dpkg</prgn> doesn't know
4013 in advance that the package is going to
4020 Any files in the package we're unpacking that are also
4021 listed in the file lists of other packages are removed
4022 from those lists. (This will lobotomize the file list
4023 of the "conflicting" package if there is one.)
4027 The backup files made during installation, above, are
4033 The new package's status is now sane, and recorded as
4038 Here is another point of no return - if the
4039 conflicting package's removal fails we do not unwind
4040 the rest of the installation; the conflicting package
4041 is left in a half-removed limbo.
4046 If there was a conflicting package we go and do the
4047 removal actions (described below), starting with the
4048 removal of the conflicting package's files (any that
4049 are also in the package being installed have already
4050 been removed from the conflicting package's file list,
4051 and so do not get removed now).
4057 <sect id="configdetails"><heading>Details of configuration</heading>
4060 When we configure a package (this happens with <tt>dpkg
4061 --install</tt> and <tt>dpkg --configure</tt>), we first
4062 update any <tt>conffile</tt>s and then call:
4063 <example compact="compact">
4064 <var>postinst</var> configure <var>most-recently-configured-version</var>
4069 No attempt is made to unwind after errors during
4070 configuration. If the configuration fails, the package is in
4071 a "Failed Config" state, and an error message is generated.
4075 If there is no most recently configured version
4076 <prgn>dpkg</prgn> will pass a null argument.
4079 Historical note: Truly ancient (pre-1997) versions of
4080 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4081 (including the angle brackets) in this case. Even older
4082 ones did not pass a second argument at all, under any
4083 circumstance. Note that upgrades using such an old dpkg
4084 version are unlikely to work for other reasons, even if
4085 this old argument behavior is handled by your postinst script.
4091 <sect id="removedetails"><heading>Details of removal and/or
4092 configuration purging</heading>
4098 <example compact="compact">
4099 <var>prerm</var> remove
4103 If prerm fails during replacement due to conflict
4105 <var>conflictor's-postinst</var> abort-remove \
4106 in-favour <var>package</var> <var>new-version</var>
4110 <var>postinst</var> abort-remove
4114 If this fails, the package is in a "Half-Configured"
4115 state, or else it remains "Installed".
4119 The package's files are removed (except <tt>conffile</tt>s).
4122 <example compact="compact">
4123 <var>postrm</var> remove
4127 If it fails, there's no error unwind, and the package is in
4128 an "Half-Installed" state.
4133 All the maintainer scripts except the <prgn>postrm</prgn>
4138 If we aren't purging the package we stop here. Note
4139 that packages which have no <prgn>postrm</prgn> and no
4140 <tt>conffile</tt>s are automatically purged when
4141 removed, as there is no difference except for the
4142 <prgn>dpkg</prgn> status.
4146 The <tt>conffile</tt>s and any backup files
4147 (<tt>~</tt>-files, <tt>#*#</tt> files,
4148 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4153 <example compact="compact">
4154 <var>postrm</var> purge
4158 If this fails, the package remains in a "Config-Files"
4163 The package's file list is removed.
4172 <chapt id="relationships">
4173 <heading>Declaring relationships between packages</heading>
4175 <sect id="depsyntax">
4176 <heading>Syntax of relationship fields</heading>
4179 These fields all have a uniform syntax. They are a list of
4180 package names separated by commas.
4184 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4185 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4186 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4187 control file fields of the package, which declare
4188 dependencies on other packages, the package names listed may
4189 also include lists of alternative package names, separated
4190 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4191 if any one of the alternative packages is installed, that
4192 part of the dependency is considered to be satisfied.
4196 All of the fields except for <tt>Provides</tt> may restrict
4197 their applicability to particular versions of each named
4198 package. This is done in parentheses after each individual
4199 package name; the parentheses should contain a relation from
4200 the list below followed by a version number, in the format
4201 described in <ref id="f-Version">.
4205 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4206 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4207 strictly earlier, earlier or equal, exactly equal, later or
4208 equal and strictly later, respectively. The deprecated
4209 forms <tt><</tt> and <tt>></tt> were used to mean
4210 earlier/later or equal, rather than strictly earlier/later,
4211 so they should not appear in new packages (though
4212 <prgn>dpkg</prgn> still supports them).
4216 Whitespace may appear at any point in the version
4217 specification subject to the rules in <ref
4218 id="controlsyntax">, and must appear where it's necessary to
4219 disambiguate; it is not otherwise significant. All of the
4220 relationship fields may span multiple lines. For
4221 consistency and in case of future changes to
4222 <prgn>dpkg</prgn> it is recommended that a single space be
4223 used after a version relationship and before a version
4224 number; it is also conventional to put a single space after
4225 each comma, on either side of each vertical bar, and before
4226 each open parenthesis. When wrapping a relationship field, it
4227 is conventional to do so after a comma and before the space
4228 following that comma.
4232 For example, a list of dependencies might appear as:
4233 <example compact="compact">
4236 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4241 All fields that specify build-time relationships
4242 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4243 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
4244 may be restricted to a certain set of architectures. This
4245 is indicated in brackets after each individual package name and
4246 the optional version specification. The brackets enclose a
4247 list of Debian architecture names separated by whitespace.
4248 Exclamation marks may be prepended to each of the names.
4249 (It is not permitted for some names to be prepended with
4250 exclamation marks while others aren't.) If the current Debian
4251 host architecture is not in this list and there are no
4252 exclamation marks in the list, or it is in the list with a
4253 prepended exclamation mark, the package name and the
4254 associated version specification are ignored completely for
4255 the purposes of defining the relationships.
4260 <example compact="compact">
4262 Build-Depends-Indep: texinfo
4263 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4264 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4266 requires <tt>kernel-headers-2.2.10</tt> on all architectures
4267 other than hurd-i386 and requires <tt>hurd-dev</tt> and
4268 <tt>gnumach-dev</tt> only on hurd-i386.
4272 If the architecture-restricted dependency is part of a set of
4273 alternatives using <tt>|</tt>, that alternative is ignored
4274 completely on architectures that do not match the restriction.
4276 <example compact="compact">
4277 Build-Depends: foo [!i386] | bar [!amd64]
4279 is equivalent to <tt>bar</tt> on the i386 architecture, to
4280 <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
4281 bar</tt> on all other architectures.
4285 All fields that specify build-time relationships may also be
4286 restricted to a certain set of architectures using architecture
4287 wildcards. The syntax for declaring such restrictions is the
4288 same as declaring restrictions using a certain set of
4289 architectures without architecture wildcards. For example:
4290 <example compact="compact">
4291 Build-Depends: foo [linux-any], bar [any-i386], baz [!linux-any]
4293 is equivalent to <tt>foo</tt> on architectures using the Linux
4294 kernel and any cpu, <tt>bar</tt> on architectures using any
4295 kernel and an i386 cpu, and <tt>baz</tt> on any architecture
4296 using a kernel other than Linux.
4300 Note that the binary package relationship fields such as
4301 <tt>Depends</tt> appear in one of the binary package
4302 sections of the control file, whereas the build-time
4303 relationships such as <tt>Build-Depends</tt> appear in the
4304 source package section of the control file (which is the
4309 <sect id="binarydeps">
4310 <heading>Binary Dependencies - <tt>Depends</tt>,
4311 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4312 <tt>Pre-Depends</tt>
4316 Packages can declare in their control file that they have
4317 certain relationships to other packages - for example, that
4318 they may not be installed at the same time as certain other
4319 packages, and/or that they depend on the presence of others.
4323 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4324 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4325 <tt>Breaks</tt> and <tt>Conflicts</tt> control file fields.
4326 <tt>Breaks</tt> is described in <ref id="breaks">, and
4327 <tt>Conflicts</tt> is described in <ref id="conflicts">. The
4328 rest are described below.
4332 These seven fields are used to declare a dependency
4333 relationship by one package on another. Except for
4334 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4335 depending (binary) package's control file.
4336 (<tt>Enhances</tt> appears in the recommending package's
4337 control file, and <tt>Breaks</tt> appears in the version of
4338 depended-on package which causes the named package to
4343 A <tt>Depends</tt> field takes effect <em>only</em> when a
4344 package is to be configured. It does not prevent a package
4345 being on the system in an unconfigured state while its
4346 dependencies are unsatisfied, and it is possible to replace
4347 a package whose dependencies are satisfied and which is
4348 properly installed with a different version whose
4349 dependencies are not and cannot be satisfied; when this is
4350 done the depending package will be left unconfigured (since
4351 attempts to configure it will give errors) and will not
4352 function properly. If it is necessary, a
4353 <tt>Pre-Depends</tt> field can be used, which has a partial
4354 effect even when a package is being unpacked, as explained
4355 in detail below. (The other three dependency fields,
4356 <tt>Recommends</tt>, <tt>Suggests</tt> and
4357 <tt>Enhances</tt>, are only used by the various front-ends
4358 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4359 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4363 For this reason packages in an installation run are usually
4364 all unpacked first and all configured later; this gives
4365 later versions of packages with dependencies on later
4366 versions of other packages the opportunity to have their
4367 dependencies satisfied.
4371 In case of circular dependencies, since installation or
4372 removal order honoring the dependency order can't be
4373 established, dependency loops are broken at some point
4374 (based on rules below), and some packages may not be able to
4375 rely on their dependencies being present when being
4376 installed or removed, depending on which side of the break
4377 of the circular dependency loop they happen to be on. If one
4378 of the packages in the loop has no postinst script, then the
4379 cycle will be broken at that package, so as to ensure that
4380 all postinst scripts run with the dependencies properly
4381 configured if this is possible. Otherwise the breaking point
4386 The <tt>Depends</tt> field thus allows package maintainers
4387 to impose an order in which packages should be configured.
4391 The meaning of the five dependency fields is as follows:
4393 <tag><tt>Depends</tt></tag>
4396 This declares an absolute dependency. A package will
4397 not be configured unless all of the packages listed in
4398 its <tt>Depends</tt> field have been correctly
4403 The <tt>Depends</tt> field should be used if the
4404 depended-on package is required for the depending
4405 package to provide a significant amount of
4410 The <tt>Depends</tt> field should also be used if the
4411 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4412 <prgn>postrm</prgn> scripts require the package to be
4413 present in order to run. Note, however, that the
4414 <prgn>postrm</prgn> cannot rely on any non-essential
4415 packages to be present during the <tt>purge</tt>
4419 <tag><tt>Recommends</tt></tag>
4422 This declares a strong, but not absolute, dependency.
4426 The <tt>Recommends</tt> field should list packages
4427 that would be found together with this one in all but
4428 unusual installations.
4432 <tag><tt>Suggests</tt></tag>
4434 This is used to declare that one package may be more
4435 useful with one or more others. Using this field
4436 tells the packaging system and the user that the
4437 listed packages are related to this one and can
4438 perhaps enhance its usefulness, but that installing
4439 this one without them is perfectly reasonable.
4442 <tag><tt>Enhances</tt></tag>
4444 This field is similar to Suggests but works in the
4445 opposite direction. It is used to declare that a
4446 package can enhance the functionality of another
4450 <tag><tt>Pre-Depends</tt></tag>
4453 This field is like <tt>Depends</tt>, except that it
4454 also forces <prgn>dpkg</prgn> to complete installation
4455 of the packages named before even starting the
4456 installation of the package which declares the
4457 pre-dependency, as follows:
4461 When a package declaring a pre-dependency is about to
4462 be <em>unpacked</em> the pre-dependency can be
4463 satisfied if the depended-on package is either fully
4464 configured, <em>or even if</em> the depended-on
4465 package(s) are only unpacked or in the "Half-Configured"
4466 state, provided that they have been configured
4467 correctly at some point in the past (and not removed
4468 or partially removed since). In this case, both the
4469 previously-configured and currently unpacked or
4470 "Half-Configured" versions must satisfy any version
4471 clause in the <tt>Pre-Depends</tt> field.
4475 When the package declaring a pre-dependency is about
4476 to be <em>configured</em>, the pre-dependency will be
4477 treated as a normal <tt>Depends</tt>, that is, it will
4478 be considered satisfied only if the depended-on
4479 package has been correctly configured.
4483 <tt>Pre-Depends</tt> should be used sparingly,
4484 preferably only by packages whose premature upgrade or
4485 installation would hamper the ability of the system to
4486 continue with any upgrade that might be in progress.
4490 <tt>Pre-Depends</tt> are also required if the
4491 <prgn>preinst</prgn> script depends on the named
4492 package. It is best to avoid this situation if
4500 When selecting which level of dependency to use you should
4501 consider how important the depended-on package is to the
4502 functionality of the one declaring the dependency. Some
4503 packages are composed of components of varying degrees of
4504 importance. Such a package should list using
4505 <tt>Depends</tt> the package(s) which are required by the
4506 more important components. The other components'
4507 requirements may be mentioned as Suggestions or
4508 Recommendations, as appropriate to the components' relative
4514 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4517 When one binary package declares that it breaks another,
4518 <prgn>dpkg</prgn> will refuse to allow the package which
4519 declares <tt>Breaks</tt> be installed unless the broken
4520 package is deconfigured first, and it will refuse to
4521 allow the broken package to be reconfigured.
4525 A package will not be regarded as causing breakage merely
4526 because its configuration files are still installed; it must
4527 be at least "Half-Installed".
4531 A special exception is made for packages which declare that
4532 they break their own package name or a virtual package which
4533 they provide (see below): this does not count as a real
4538 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4539 version clause; such a <tt>Breaks</tt> is introduced in the
4540 version of an (implicit or explicit) dependency which
4541 violates an assumption or reveals a bug in earlier versions
4542 of the broken package. This use of <tt>Breaks</tt> will
4543 inform higher-level package management tools that broken
4544 package must be upgraded before the new one.
4548 If the breaking package also overwrites some files from the
4549 older package, it should use <tt>Replaces</tt> (not
4550 <tt>Conflicts</tt>) to ensure this goes smoothly.
4554 <sect id="conflicts">
4555 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4558 When one binary package declares a conflict with another
4559 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4560 refuse to allow them to be installed on the system at the
4565 If one package is to be installed, the other must be removed
4566 first - if the package being installed is marked as
4567 replacing (see <ref id="replaces">) the one on the system,
4568 or the one on the system is marked as deselected, or both
4569 packages are marked <tt>Essential</tt>, then
4570 <prgn>dpkg</prgn> will automatically remove the package
4571 which is causing the conflict, otherwise it will halt the
4572 installation of the new package with an error. This
4573 mechanism is specifically designed to produce an error when
4574 the installed package is <tt>Essential</tt>, but the new
4579 A package will not cause a conflict merely because its
4580 configuration files are still installed; it must be at least
4585 A special exception is made for packages which declare a
4586 conflict with their own package name, or with a virtual
4587 package which they provide (see below): this does not
4588 prevent their installation, and allows a package to conflict
4589 with others providing a replacement for it. You use this
4590 feature when you want the package in question to be the only
4591 package providing some feature.
4595 A <tt>Conflicts</tt> entry should almost never have an
4596 "earlier than" version clause. This would prevent
4597 <prgn>dpkg</prgn> from upgrading or installing the package
4598 which declared such a conflict until the upgrade or removal
4599 of the conflicted-with package had been completed. Instead,
4600 <tt>Breaks</tt> may be used.
4604 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4608 As well as the names of actual ("concrete") packages, the
4609 package relationship fields <tt>Depends</tt>,
4610 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4611 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4612 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4613 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4614 may mention "virtual packages".
4618 A <em>virtual package</em> is one which appears in the
4619 <tt>Provides</tt> control file field of another package.
4620 The effect is as if the package(s) which provide a
4621 particular virtual package name had been listed by name
4622 everywhere the virtual package name appears. (See also <ref
4627 If there are both concrete and virtual packages of the same
4628 name, then the dependency may be satisfied (or the conflict
4629 caused) by either the concrete package with the name in
4630 question or any other concrete package which provides the
4631 virtual package with the name in question. This is so that,
4632 for example, supposing we have
4633 <example compact="compact">
4636 </example> and someone else releases an enhanced version of
4637 the <tt>bar</tt> package they can say:
4638 <example compact="compact">
4642 and the <tt>bar-plus</tt> package will now also satisfy the
4643 dependency for the <tt>foo</tt> package.
4647 If a relationship field has a version number attached
4648 then only real packages will be considered to see whether
4649 the relationship is satisfied (or the prohibition violated,
4650 for a conflict or breakage) - it is assumed that a real
4651 package which provides the virtual package is not of the
4652 "right" version. So, a <tt>Provides</tt> field may not
4653 contain version numbers, and the version number of the
4654 concrete package which provides a particular virtual package
4655 will not be looked at when considering a dependency on or
4656 conflict with the virtual package name.
4660 It is likely that the ability will be added in a future
4661 release of <prgn>dpkg</prgn> to specify a version number for
4662 each virtual package it provides. This feature is not yet
4663 present, however, and is expected to be used only
4668 If you want to specify which of a set of real packages
4669 should be the default to satisfy a particular dependency on
4670 a virtual package, you should list the real package as an
4671 alternative before the virtual one.
4676 <sect id="replaces"><heading>Overwriting files and replacing
4677 packages - <tt>Replaces</tt></heading>
4680 Packages can declare in their control file that they should
4681 overwrite files in certain other packages, or completely
4682 replace other packages. The <tt>Replaces</tt> control file
4683 field has these two distinct purposes.
4686 <sect1><heading>Overwriting files in other packages</heading>
4689 Firstly, as mentioned before, it is usually an error for a
4690 package to contain files which are on the system in
4695 However, if the overwriting package declares that it
4696 <tt>Replaces</tt> the one containing the file being
4697 overwritten, then <prgn>dpkg</prgn> will replace the file
4698 from the old package with that from the new. The file
4699 will no longer be listed as "owned" by the old package.
4703 If a package is completely replaced in this way, so that
4704 <prgn>dpkg</prgn> does not know of any files it still
4705 contains, it is considered to have "disappeared". It will
4706 be marked as not wanted on the system (selected for
4707 removal) and not installed. Any <tt>conffile</tt>s
4708 details noted for the package will be ignored, as they
4709 will have been taken over by the overwriting package. The
4710 package's <prgn>postrm</prgn> script will be run with a
4711 special argument to allow the package to do any final
4712 cleanup required. See <ref id="mscriptsinstact">.
4715 Replaces is a one way relationship -- you have to
4716 install the replacing package after the replaced
4723 For this usage of <tt>Replaces</tt>, virtual packages (see
4724 <ref id="virtual">) are not considered when looking at a
4725 <tt>Replaces</tt> field - the packages declared as being
4726 replaced must be mentioned by their real names.
4730 Furthermore, this usage of <tt>Replaces</tt> only takes
4731 effect when both packages are at least partially on the
4732 system at once, so that it can only happen if they do not
4733 conflict or if the conflict has been overridden.
4738 <sect1><heading>Replacing whole packages, forcing their
4742 Secondly, <tt>Replaces</tt> allows the packaging system to
4743 resolve which package should be removed when there is a
4744 conflict - see <ref id="conflicts">. This usage only
4745 takes effect when the two packages <em>do</em> conflict,
4746 so that the two usages of this field do not interfere with
4751 In this situation, the package declared as being replaced
4752 can be a virtual package, so for example, all mail
4753 transport agents (MTAs) would have the following fields in
4754 their control files:
4755 <example compact="compact">
4756 Provides: mail-transport-agent
4757 Conflicts: mail-transport-agent
4758 Replaces: mail-transport-agent
4760 ensuring that only one MTA can be installed at any one
4765 <sect id="sourcebinarydeps">
4766 <heading>Relationships between source and binary packages -
4767 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4768 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4772 Source packages that require certain binary packages to be
4773 installed or absent at the time of building the package
4774 can declare relationships to those binary packages.
4778 This is done using the <tt>Build-Depends</tt>,
4779 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4780 <tt>Build-Conflicts-Indep</tt> control file fields.
4784 Build-dependencies on "build-essential" binary packages can be
4785 omitted. Please see <ref id="pkg-relations"> for more information.
4789 The dependencies and conflicts they define must be satisfied
4790 (as defined earlier for binary packages) in order to invoke
4791 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4793 If you make "build-arch" or "binary-arch", you need
4794 Build-Depends. If you make "build-indep" or
4795 "binary-indep", you need Build-Depends and
4796 Build-Depends-Indep. If you make "build" or "binary",
4800 There is no Build-Depends-Arch; this role is essentially
4801 met with Build-Depends. Anyone building the
4802 <tt>build-indep</tt> and binary-indep<tt></tt> targets
4803 is basically assumed to be building the whole package
4804 anyway and so installs all build dependencies. The
4805 autobuilders use <tt>dpkg-buildpackage -B</tt>, which
4806 calls <tt>build</tt> (not <tt>build-arch</tt>, since it
4807 does not yet know how to check for its existence) and
4808 <tt>binary-arch</tt>.
4811 The purpose of the original split, I recall, was so that
4812 the autobuilders wouldn't need to install extra packages
4813 needed only for the binary-indep targets. But without a
4814 build-arch/build-indep split, this didn't work, since
4815 most of the work is done in the build target, not in the
4821 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4823 The <tt>Build-Depends</tt> and
4824 <tt>Build-Conflicts</tt> fields must be satisfied when
4825 any of the following targets is invoked:
4826 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4827 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4828 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4830 <tag><tt>Build-Depends-Indep</tt>,
4831 <tt>Build-Conflicts-Indep</tt></tag>
4833 The <tt>Build-Depends-Indep</tt> and
4834 <tt>Build-Conflicts-Indep</tt> fields must be
4835 satisfied when any of the following targets is
4836 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4837 <tt>binary</tt> and <tt>binary-indep</tt>.
4847 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4850 Packages containing shared libraries must be constructed with
4851 a little care to make sure that the shared library is always
4852 available. This is especially important for packages whose
4853 shared libraries are vitally important, such as the C library
4854 (currently <tt>libc6</tt>).
4858 Packages involving shared libraries should be split up into
4859 several binary packages. This section mostly deals with how
4860 this separation is to be accomplished; rules for files within
4861 the shared library packages are in <ref id="libraries"> instead.
4864 <sect id="sharedlibs-runtime">
4865 <heading>Run-time shared libraries</heading>
4868 The run-time shared library needs to be placed in a package
4869 whose name changes whenever the shared object version
4872 Since it is common place to install several versions of a
4873 package that just provides shared libraries, it is a
4874 good idea that the library package should not
4875 contain any extraneous non-versioned files, unless they
4876 happen to be in versioned directories.</p>
4878 The most common mechanism is to place it in a package
4880 <package><var>libraryname</var><var>soversion</var></package>,
4881 where <file><var>soversion</var></file> is the version number
4882 in the soname of the shared library<footnote>
4883 The soname is the shared object name: it's the thing
4884 that has to match exactly between building an executable
4885 and running it for the dynamic linker to be able run the
4886 program. For example, if the soname of the library is
4887 <file>libfoo.so.6</file>, the library package would be
4888 called <file>libfoo6</file>.
4890 Alternatively, if it would be confusing to directly append
4891 <var>soversion</var> to <var>libraryname</var> (e.g. because
4892 <var>libraryname</var> itself ends in a number), you may use
4893 <package><var>libraryname</var>-<var>soversion</var></package> and
4894 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4899 If you have several shared libraries built from the same
4900 source tree you may lump them all together into a single
4901 shared library package, provided that you change all of
4902 their sonames at once (so that you don't get filename
4903 clashes if you try to install different versions of the
4904 combined shared libraries package).
4908 The package should install the shared libraries under
4909 their normal names. For example, the <package>libgdbm3</package>
4910 package should install <file>libgdbm.so.3.0.0</file> as
4911 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4912 renamed or re-linked by any <prgn>prerm</prgn> or
4913 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4914 of renaming things safely without affecting running programs,
4915 and attempts to interfere with this are likely to lead to
4920 Shared libraries should not be installed executable, since
4921 the dynamic linker does not require this and trying to
4922 execute a shared library usually results in a core dump.
4926 The run-time library package should include the symbolic link that
4927 <prgn>ldconfig</prgn> would create for the shared libraries.
4928 For example, the <package>libgdbm3</package> package should include
4929 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4930 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4931 linker (for example <prgn>ld.so</prgn> or
4932 <prgn>ld-linux.so.*</prgn>) can find the library between the
4933 time that <prgn>dpkg</prgn> installs it and the time that
4934 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4936 The package management system requires the library to be
4937 placed before the symbolic link pointing to it in the
4938 <file>.deb</file> file. This is so that when
4939 <prgn>dpkg</prgn> comes to install the symlink
4940 (overwriting the previous symlink pointing at an older
4941 version of the library), the new shared library is already
4942 in place. In the past, this was achieved by creating the
4943 library in the temporary packaging directory before
4944 creating the symlink. Unfortunately, this was not always
4945 effective, since the building of the tar file in the
4946 <file>.deb</file> depended on the behavior of the underlying
4947 file system. Some file systems (such as reiserfs) reorder
4948 the files so that the order of creation is forgotten.
4949 Since version 1.7.0, <prgn>dpkg</prgn>
4950 reorders the files itself as necessary when building a
4951 package. Thus it is no longer important to concern
4952 oneself with the order of file creation.
4956 <sect1 id="ldconfig">
4957 <heading><tt>ldconfig</tt></heading>
4960 Any package installing shared libraries in one of the default
4961 library directories of the dynamic linker (which are currently
4962 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4963 listed in <file>/etc/ld.so.conf</file><footnote>
4965 <list compact="compact">
4966 <item>/usr/local/lib</item>
4967 <item>/usr/lib/libc5-compat</item>
4968 <item>/lib/libc5-compat</item>
4971 must use <prgn>ldconfig</prgn> to update the shared library
4976 The package maintainer scripts must only call
4977 <prgn>ldconfig</prgn> under these circumstances:
4978 <list compact="compact">
4979 <item>When the <prgn>postinst</prgn> script is run with a
4980 first argument of <tt>configure</tt>, the script must call
4981 <prgn>ldconfig</prgn>, and may optionally invoke
4982 <prgn>ldconfig</prgn> at other times.
4984 <item>When the <prgn>postrm</prgn> script is run with a
4985 first argument of <tt>remove</tt>, the script should call
4986 <prgn>ldconfig</prgn>.
4991 During install or upgrade, the preinst is called before
4992 the new files are installed, so calling "ldconfig" is
4993 pointless. The preinst of an existing package can also be
4994 called if an upgrade fails. However, this happens during
4995 the critical time when a shared libs may exist on-disk
4996 under a temporary name. Thus, it is dangerous and
4997 forbidden by current policy to call "ldconfig" at this
5002 When a package is installed or upgraded, "postinst
5003 configure" runs after the new files are safely on-disk.
5004 Since it is perfectly safe to invoke ldconfig
5005 unconditionally in a postinst, it is OK for a package to
5006 simply put ldconfig in its postinst without checking the
5007 argument. The postinst can also be called to recover from
5008 a failed upgrade. This happens before any new files are
5009 unpacked, so there is no reason to call "ldconfig" at this
5014 For a package that is being removed, prerm is
5015 called with all the files intact, so calling ldconfig is
5016 useless. The other calls to "prerm" happen in the case of
5017 upgrade at a time when all the files of the old package
5018 are on-disk, so again calling "ldconfig" is pointless.
5022 postrm, on the other hand, is called with the "remove"
5023 argument just after the files are removed, so this is
5024 the proper time to call "ldconfig" to notify the system
5025 of the fact that the shared libraries from the package
5026 are removed. The postrm can be called at several other
5027 times. At the time of "postrm purge", "postrm
5028 abort-install", or "postrm abort-upgrade", calling
5029 "ldconfig" is useless because the shared lib files are
5030 not on-disk. However, when "postrm" is invoked with
5031 arguments "upgrade", "failed-upgrade", or "disappear", a
5032 shared lib may exist on-disk under a temporary filename.
5040 <sect id="sharedlibs-support-files">
5041 <heading>Shared library support files</heading>
5044 If your package contains files whose names do not change with
5045 each change in the library shared object version, you must not
5046 put them in the shared library package. Otherwise, several
5047 versions of the shared library cannot be installed at the same
5048 time without filename clashes, making upgrades and transitions
5049 unnecessarily difficult.
5053 It is recommended that supporting files and run-time support
5054 programs that do not need to be invoked manually by users, but
5055 are nevertheless required for the package to function, be placed
5056 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
5057 preferably under <file>/usr/lib/</file><var>package-name</var>.
5058 If the program or file is architecture independent, the
5059 recommendation is for it to be placed in a subdirectory of
5060 <file>/usr/share</file> instead, preferably under
5061 <file>/usr/share/</file><var>package-name</var>. Following the
5062 <var>package-name</var> naming convention ensures that the file
5063 names change when the shared object version changes.
5067 Run-time support programs that use the shared library but are
5068 not required for the library to function or files used by the
5069 shared library that can be used by any version of the shared
5070 library package should instead be put in a separate package.
5071 This package might typically be named
5072 <package><var>libraryname</var>-tools</package>; note the
5073 absence of the <var>soversion</var> in the package name.
5077 Files and support programs only useful when compiling software
5078 against the library should be included in the development
5079 package for the library.<footnote>
5080 For example, a <file><var>package-name</var>-config</file>
5081 script or <package>pkg-config</package> configuration files.
5086 <sect id="sharedlibs-static">
5087 <heading>Static libraries</heading>
5090 The static library (<file><var>libraryname.a</var></file>)
5091 is usually provided in addition to the shared version.
5092 It is placed into the development package (see below).
5096 In some cases, it is acceptable for a library to be
5097 available in static form only; these cases include:
5099 <item>libraries for languages whose shared library support
5100 is immature or unstable</item>
5101 <item>libraries whose interfaces are in flux or under
5102 development (commonly the case when the library's
5103 major version number is zero, or where the ABI breaks
5104 across patchlevels)</item>
5105 <item>libraries which are explicitly intended to be
5106 available only in static form by their upstream
5111 <sect id="sharedlibs-dev">
5112 <heading>Development files</heading>
5115 The development files associated to a shared library need to be
5116 placed in a package called
5117 <package><var>libraryname</var><var>soversion</var>-dev</package>,
5118 or if you prefer only to support one development version at a
5119 time, <package><var>libraryname</var>-dev</package>.
5123 In case several development versions of a library exist, you may
5124 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5125 <ref id="conflicts">) to ensure that the user only installs one
5126 development version at a time (as different development versions are
5127 likely to have the same header files in them, which would cause a
5128 filename clash if both were installed).
5132 The development package should contain a symlink for the associated
5133 shared library without a version number. For example, the
5134 <package>libgdbm-dev</package> package should include a symlink
5135 from <file>/usr/lib/libgdbm.so</file> to
5136 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5137 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5138 <file>libgdbm.so</file> when compiling dynamically.
5142 <sect id="sharedlibs-intradeps">
5143 <heading>Dependencies between the packages of the same library</heading>
5146 Typically the development version should have an exact
5147 version dependency on the runtime library, to make sure that
5148 compilation and linking happens correctly. The
5149 <tt>${binary:Version}</tt> substitution variable can be
5150 useful for this purpose.
5152 Previously, <tt>${Source-Version}</tt> was used, but its name
5153 was confusing and it has been deprecated since dpkg 1.13.19.
5158 <sect id="sharedlibs-shlibdeps">
5159 <heading>Dependencies between the library and other packages -
5160 the <tt>shlibs</tt> system</heading>
5163 If a package contains a binary or library which links to a
5164 shared library, we must ensure that when the package is
5165 installed on the system, all of the libraries needed are
5166 also installed. This requirement led to the creation of the
5167 <tt>shlibs</tt> system, which is very simple in its design:
5168 any package which <em>provides</em> a shared library also
5169 provides information on the package dependencies required to
5170 ensure the presence of this library, and any package which
5171 <em>uses</em> a shared library uses this information to
5172 determine the dependencies it requires. The files which
5173 contain the mapping from shared libraries to the necessary
5174 dependency information are called <file>shlibs</file> files.
5178 Thus, when a package is built which contains any shared
5179 libraries, it must provide a <file>shlibs</file> file for other
5180 packages to use, and when a package is built which contains
5181 any shared libraries or compiled binaries, it must run
5182 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5183 on these to determine the libraries used and hence the
5184 dependencies needed by this package.<footnote>
5186 In the past, the shared libraries linked to were
5187 determined by calling <prgn>ldd</prgn>, but now
5188 <prgn>objdump</prgn> is used to do this. The only
5189 change this makes to package building is that
5190 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
5191 libraries, whereas in the past this was unnecessary.
5192 The rest of this footnote explains the advantage that
5197 We say that a binary <tt>foo</tt> <em>directly</em> uses
5198 a library <tt>libbar</tt> if it is explicitly linked
5199 with that library (that is, it uses the flag
5200 <tt>-lbar</tt> during the linking stage). Other
5201 libraries that are needed by <tt>libbar</tt> are linked
5202 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5203 linker will load them automatically when it loads
5204 <tt>libbar</tt>. A package should depend on
5205 the libraries it directly uses, and the dependencies for
5206 those libraries should automatically pull in the other
5211 Unfortunately, the <prgn>ldd</prgn> program shows both
5212 the directly and indirectly used libraries, meaning that
5213 the dependencies determined included both direct and
5214 indirect dependencies. The use of <prgn>objdump</prgn>
5215 avoids this problem by determining only the directly
5220 A good example of where this helps is the following. We
5221 could update <tt>libimlib</tt> with a new version that
5222 supports a new graphics format called dgf (but retaining
5223 the same major version number). If we used the old
5224 <prgn>ldd</prgn> method, every package that uses
5225 <tt>libimlib</tt> would need to be recompiled so it
5226 would also depend on <tt>libdgf</tt> or it wouldn't run
5227 due to missing symbols. However with the new system,
5228 packages using <tt>libimlib</tt> can rely on
5229 <tt>libimlib</tt> itself having the dependency on
5230 <tt>libdgf</tt> and so they would not need rebuilding.
5236 In the following sections, we will first describe where the
5237 various <tt>shlibs</tt> files are to be found, then how to
5238 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5239 file format and how to create them if your package contains a
5244 <heading>The <tt>shlibs</tt> files present on the system</heading>
5247 There are several places where <tt>shlibs</tt> files are
5248 found. The following list gives them in the order in which
5250 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5251 (The first one which gives the required information is used.)
5257 <p><file>debian/shlibs.local</file></p>
5260 This lists overrides for this package. Its use is
5261 described below (see <ref id="shlibslocal">).
5266 <p><file>/etc/dpkg/shlibs.override</file></p>
5269 This lists global overrides. This list is normally
5270 empty. It is maintained by the local system
5276 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5279 When packages are being built, any
5280 <file>debian/shlibs</file> files are copied into the
5281 control file area of the temporary build directory and
5282 given the name <file>shlibs</file>. These files give
5283 details of any shared libraries included in the
5285 An example may help here. Let us say that the
5286 source package <tt>foo</tt> generates two binary
5287 packages, <tt>libfoo2</tt> and
5288 <tt>foo-runtime</tt>. When building the binary
5289 packages, the two packages are created in the
5290 directories <file>debian/libfoo2</file> and
5291 <file>debian/foo-runtime</file> respectively.
5292 (<file>debian/tmp</file> could be used instead of one
5293 of these.) Since <tt>libfoo2</tt> provides the
5294 <tt>libfoo</tt> shared library, it will require a
5295 <tt>shlibs</tt> file, which will be installed in
5296 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
5298 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
5299 when <prgn>dpkg-shlibdeps</prgn> is run on the
5301 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
5303 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5304 determine whether <tt>foo-prog</tt>'s library
5305 dependencies are satisfied by any of the libraries
5306 provided by <tt>libfoo2</tt>. For this reason,
5307 <prgn>dpkg-shlibdeps</prgn> must only be run once
5308 all of the individual binary packages'
5309 <tt>shlibs</tt> files have been installed into the
5316 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5319 These are the <file>shlibs</file> files corresponding to
5320 all of the packages installed on the system, and are
5321 maintained by the relevant package maintainers.
5326 <p><file>/etc/dpkg/shlibs.default</file></p>
5329 This file lists any shared libraries whose packages
5330 have failed to provide correct <file>shlibs</file> files.
5331 It was used when the <file>shlibs</file> setup was first
5332 introduced, but it is now normally empty. It is
5333 maintained by the <tt>dpkg</tt> maintainer.
5341 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5342 <file>shlibs</file> files</heading>
5346 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5347 into your <file>debian/rules</file> file. If your package
5348 contains only compiled binaries and libraries (but no scripts),
5349 you can use a command such as:
5350 <example compact="compact">
5351 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5352 debian/tmp/usr/lib/*
5354 Otherwise, you will need to explicitly list the compiled
5355 binaries and libraries.<footnote>
5356 If you are using <tt>debhelper</tt>, the
5357 <prgn>dh_shlibdeps</prgn> program will do this work for
5358 you. It will also correctly handle multi-binary
5364 This command puts the dependency information into the
5365 <file>debian/substvars</file> file, which is then used by
5366 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5367 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5368 field in the control file for this to work.
5372 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
5373 done. If it does complain you might need to create your own
5374 <file>debian/shlibs.local</file> file, as explained below (see
5375 <ref id="shlibslocal">).
5379 If you have multiple binary packages, you will need to call
5380 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5381 compiled libraries or binaries. In such a case, you will
5382 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5383 utilities to specify a different <file>substvars</file> file.
5387 If you are creating a udeb for use in the Debian Installer,
5388 you will need to specify that <prgn>dpkg-shlibdeps</prgn>
5389 should use the dependency line of type <tt>udeb</tt> by
5390 adding the <tt>-tudeb</tt> option<footnote>
5391 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5392 will automatically add this option if it knows it is
5394 </footnote>. If there is no dependency line of type <tt>udeb</tt>
5395 in the <file>shlibs</file> file, <prgn>dpkg-shlibdeps</prgn> will
5396 fall back to the regular dependency line.
5400 For more details on dpkg-shlibdeps, please see
5401 <ref id="pkg-dpkg-shlibdeps"> and
5402 <manref name="dpkg-shlibdeps" section="1">.
5407 <heading>The <file>shlibs</file> File Format</heading>
5410 Each <file>shlibs</file> file has the same format. Lines
5411 beginning with <tt>#</tt> are considered to be comments and
5412 are ignored. Each line is of the form:
5413 <example compact="compact">
5414 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5419 We will explain this by reference to the example of the
5420 <tt>zlib1g</tt> package, which (at the time of writing)
5421 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5425 <var>type</var> is an optional element that indicates the type
5426 of package for which the line is valid. The only type currently
5427 in use is <tt>udeb</tt>. The colon and space after the type are
5432 <var>library-name</var> is the name of the shared library,
5433 in this case <tt>libz</tt>. (This must match the name part
5434 of the soname, see below.)
5438 <var>soname-version</var> is the version part of the soname of
5439 the library. The soname is the thing that must exactly match
5440 for the library to be recognized by the dynamic linker, and is
5442 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5443 example, <tt>libz.so.1</tt>.<footnote>
5444 This can be determined using the command
5445 <example compact="compact">
5446 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5449 The version part is the part which comes after
5450 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
5454 <var>dependencies</var> has the same syntax as a dependency
5455 field in a binary package control file. It should give
5456 details of which packages are required to satisfy a binary
5457 built against the version of the library contained in the
5458 package. See <ref id="depsyntax"> for details.
5462 In our example, if the first version of the <tt>zlib1g</tt>
5463 package which contained a minor number of at least
5464 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5465 <tt>shlibs</tt> entry for this library could say:
5466 <example compact="compact">
5467 libz 1 zlib1g (>= 1:1.1.3)
5469 The version-specific dependency is to avoid warnings from
5470 the dynamic linker about using older shared libraries with
5475 As zlib1g also provides a udeb containing the shared library,
5476 there would also be a second line:
5477 <example compact="compact">
5478 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5484 <heading>Providing a <file>shlibs</file> file</heading>
5487 If your package provides a shared library, you need to create
5488 a <file>shlibs</file> file following the format described above.
5489 It is usual to call this file <file>debian/shlibs</file> (but if
5490 you have multiple binary packages, you might want to call it
5491 <file>debian/shlibs.<var>package</var></file> instead). Then
5492 let <file>debian/rules</file> install it in the control area:
5493 <example compact="compact">
5494 install -m644 debian/shlibs debian/tmp/DEBIAN
5496 or, in the case of a multi-binary package:
5497 <example compact="compact">
5498 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5500 An alternative way of doing this is to create the
5501 <file>shlibs</file> file in the control area directly from
5502 <file>debian/rules</file> without using a <file>debian/shlibs</file>
5503 file at all,<footnote>
5504 This is what <prgn>dh_makeshlibs</prgn> in the
5505 <tt>debhelper</tt> suite does. If your package also has a udeb
5506 that provides a shared library, <prgn>dh_makeshlibs</prgn> can
5507 automatically generate the <tt>udeb:</tt> lines if you specify
5508 the name of the udeb with the <tt>--add-udeb</tt> option.
5510 since the <file>debian/shlibs</file> file itself is ignored by
5511 <prgn>dpkg-shlibdeps</prgn>.
5515 As <prgn>dpkg-shlibdeps</prgn> reads the
5516 <file>DEBIAN/shlibs</file> files in all of the binary packages
5517 being built from this source package, all of the
5518 <file>DEBIAN/shlibs</file> files should be installed before
5519 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5524 <sect1 id="shlibslocal">
5525 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
5528 This file is intended only as a <em>temporary</em> fix if
5529 your binaries or libraries depend on a library whose package
5530 does not yet provide a correct <file>shlibs</file> file.
5534 We will assume that you are trying to package a binary
5535 <tt>foo</tt>. When you try running
5536 <prgn>dpkg-shlibdeps</prgn> you get the following error
5537 message (<tt>-O</tt> displays the dependency information on
5538 <tt>stdout</tt> instead of writing it to
5539 <tt>debian/substvars</tt>, and the lines have been wrapped
5540 for ease of reading):
5541 <example compact="compact">
5542 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
5543 dpkg-shlibdeps: warning: unable to find dependency
5544 information for shared library libbar (soname 1,
5545 path /usr/lib/libbar.so.1, dependency field Depends)
5546 shlibs:Depends=libc6 (>= 2.2.2-2)
5548 You can then run <prgn>ldd</prgn> on the binary to find the
5549 full location of the library concerned:
5550 <example compact="compact">
5552 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5553 libc.so.6 => /lib/libc.so.6 (0x40032000)
5554 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5556 So the <prgn>foo</prgn> binary depends on the
5557 <prgn>libbar</prgn> shared library, but no package seems to
5558 provide a <file>*.shlibs</file> file handling
5559 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5560 determine the package responsible:
5561 <example compact="compact">
5562 $ dpkg -S /usr/lib/libbar.so.1
5563 bar1: /usr/lib/libbar.so.1
5564 $ dpkg -s bar1 | grep Version
5567 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5568 is the one we are using. Now we can file a bug against the
5569 <tt>bar1</tt> package and create our own
5570 <file>debian/shlibs.local</file> to locally fix the problem.
5571 Including the following line into your
5572 <file>debian/shlibs.local</file> file:
5573 <example compact="compact">
5574 libbar 1 bar1 (>= 1.0-1)
5576 should allow the package build to work.
5580 As soon as the maintainer of <tt>bar1</tt> provides a
5581 correct <file>shlibs</file> file, you should remove this line
5582 from your <file>debian/shlibs.local</file> file. (You should
5583 probably also then have a versioned <tt>Build-Depends</tt>
5584 on <tt>bar1</tt> to help ensure that others do not have the
5585 same problem building your package.)
5594 <chapt id="opersys"><heading>The Operating System</heading>
5597 <heading>File system hierarchy</heading>
5601 <heading>File System Structure</heading>
5604 The location of all installed files and directories must
5605 comply with the Filesystem Hierarchy Standard (FHS),
5606 version 2.3, with the exceptions noted below, and except
5607 where doing so would violate other terms of Debian
5608 Policy. The following exceptions to the FHS apply:
5613 The optional rules related to user specific
5614 configuration files for applications are stored in
5615 the user's home directory are relaxed. It is
5616 recommended that such files start with the
5617 '<tt>.</tt>' character (a "dot file"), and if an
5618 application needs to create more than one dot file
5619 then the preferred placement is in a subdirectory
5620 with a name starting with a '.' character, (a "dot
5621 directory"). In this case it is recommended the
5622 configuration files not start with the '.'
5628 The requirement for amd64 to use <file>/lib64</file>
5629 for 64 bit binaries is removed.
5634 The requirement for object files, internal binaries, and
5635 libraries, including <file>libc.so.*</file>, to be located
5636 directly under <file>/lib{,32}</file> and
5637 <file>/usr/lib{,32}</file> is amended, permitting files
5638 to instead be installed to
5639 <file>/lib/<var>triplet</var></file> and
5640 <file>/usr/lib/<var>triplet</var></file>, where
5641 <tt><var>triplet</var></tt> is the value returned by
5642 <tt>dpkg-architecture -qDEB_HOST_GNU_TYPE</tt> for the
5643 architecture of the package. Packages may <em>not</em>
5644 install files to any <var>triplet</var> path other
5645 than the one matching the architecture of that package;
5646 for instance, an <tt>Architecture: amd64</tt> package
5647 containing 32-bit x86 libraries may not install these
5648 libraries to <file>/usr/lib/i486-linux-gnu</file>.
5650 This is necessary in order to reserve the directories for
5651 use in cross-installation of library packages from other
5652 architectures, as part of the planned deployment of
5657 Applications may also use a single subdirectory under
5658 <file>/usr/lib/<var>triplet</var></file>.
5661 The execution time linker/loader, ld*, must still be made
5662 available in the existing location under /lib or /lib64
5663 since this is part of the ELF ABI for the architecture.
5668 The requirement that
5669 <file>/usr/local/share/man</file> be "synonymous"
5670 with <file>/usr/local/man</file> is relaxed to a
5675 The requirement that windowmanagers with a single
5676 configuration file call it <file>system.*wmrc</file>
5677 is removed, as is the restriction that the window
5678 manager subdirectory be named identically to the
5679 window manager name itself.
5684 The requirement that boot manager configuration
5685 files live in <file>/etc</file>, or at least are
5686 symlinked there, is relaxed to a recommendation.
5691 The following directories in the root filesystem are
5692 additionally allowed: <file>/sys</file> and
5693 <file>/selinux</file>. <footnote>These directories
5694 are used as mount points to mount virtual filesystems
5695 to get access to kernel information.</footnote>
5702 The version of this document referred here can be
5703 found in the <tt>debian-policy</tt> package or on <url
5704 id="http://www.debian.org/doc/packaging-manuals/fhs/"
5705 name="FHS (Debian copy)"> alongside this manual (or, if
5706 you have the <package>debian-policy</package> installed,
5708 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5709 (local copy)">). The
5710 latest version, which may be a more recent version, may
5712 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5713 Specific questions about following the standard may be
5714 asked on the <tt>debian-devel</tt> mailing list, or
5715 referred to the FHS mailing list (see the
5716 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5722 <heading>Site-specific programs</heading>
5725 As mandated by the FHS, packages must not place any
5726 files in <file>/usr/local</file>, either by putting them in
5727 the file system archive to be unpacked by <prgn>dpkg</prgn>
5728 or by manipulating them in their maintainer scripts.
5732 However, the package may create empty directories below
5733 <file>/usr/local</file> so that the system administrator knows
5734 where to place site-specific files. These are not
5735 directories <em>in</em> <file>/usr/local</file>, but are
5736 children of directories in <file>/usr/local</file>. These
5737 directories (<file>/usr/local/*/dir/</file>)
5738 should be removed on package removal if they are
5743 Note that this applies only to
5744 directories <em>below</em> <file>/usr/local</file>,
5745 not <em>in</em> <file>/usr/local</file>. Packages must
5746 not create sub-directories in the
5747 directory <file>/usr/local</file> itself, except those
5748 listed in FHS, section 4.5. However, you may create
5749 directories below them as you wish. You must not remove
5750 any of the directories listed in 4.5, even if you created
5755 Since <file>/usr/local</file> can be mounted read-only from a
5756 remote server, these directories must be created and
5757 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5758 maintainer scripts and not be included in the
5759 <file>.deb</file> archive. These scripts must not fail if
5760 either of these operations fail.
5764 For example, the <tt>emacsen-common</tt> package could
5765 contain something like
5766 <example compact="compact">
5767 if [ ! -e /usr/local/share/emacs ]
5769 if mkdir /usr/local/share/emacs 2>/dev/null
5771 chown root:staff /usr/local/share/emacs
5772 chmod 2775 /usr/local/share/emacs
5776 in its <prgn>postinst</prgn> script, and
5777 <example compact="compact">
5778 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5779 rmdir /usr/local/share/emacs 2>/dev/null || true
5781 in the <prgn>prerm</prgn> script. (Note that this form is
5782 used to ensure that if the script is interrupted, the
5783 directory <file>/usr/local/share/emacs</file> will still be
5788 If you do create a directory in <file>/usr/local</file> for
5789 local additions to a package, you should ensure that
5790 settings in <file>/usr/local</file> take precedence over the
5791 equivalents in <file>/usr</file>.
5795 However, because <file>/usr/local</file> and its contents are
5796 for exclusive use of the local administrator, a package
5797 must not rely on the presence or absence of files or
5798 directories in <file>/usr/local</file> for normal operation.
5802 The <file>/usr/local</file> directory itself and all the
5803 subdirectories created by the package should (by default) have
5804 permissions 2775 (group-writable and set-group-id) and be
5805 owned by <tt>root:staff</tt>.
5810 <heading>The system-wide mail directory</heading>
5812 The system-wide mail directory
5813 is <file>/var/mail</file>. This directory is part of the
5814 base system and should not be owned by any particular mail
5815 agents. The use of the old
5816 location <file>/var/spool/mail</file> is deprecated, even
5817 though the spool may still be physically located there.
5823 <heading>Users and groups</heading>
5826 <heading>Introduction</heading>
5828 The Debian system can be configured to use either plain or
5833 Some user ids (UIDs) and group ids (GIDs) are reserved
5834 globally for use by certain packages. Because some
5835 packages need to include files which are owned by these
5836 users or groups, or need the ids compiled into binaries,
5837 these ids must be used on any Debian system only for the
5838 purpose for which they are allocated. This is a serious
5839 restriction, and we should avoid getting in the way of
5840 local administration policies. In particular, many sites
5841 allocate users and/or local system groups starting at 100.
5845 Apart from this we should have dynamically allocated ids,
5846 which should by default be arranged in some sensible
5847 order, but the behavior should be configurable.
5851 Packages other than <tt>base-passwd</tt> must not modify
5852 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5853 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5858 <heading>UID and GID classes</heading>
5860 The UID and GID numbers are divided into classes as
5866 Globally allocated by the Debian project, the same
5867 on every Debian system. These ids will appear in
5868 the <file>passwd</file> and <file>group</file> files of all
5869 Debian systems, new ids in this range being added
5870 automatically as the <tt>base-passwd</tt> package is
5875 Packages which need a single statically allocated
5876 uid or gid should use one of these; their
5877 maintainers should ask the <tt>base-passwd</tt>
5885 Dynamically allocated system users and groups.
5886 Packages which need a user or group, but can have
5887 this user or group allocated dynamically and
5888 differently on each system, should use <tt>adduser
5889 --system</tt> to create the group and/or user.
5890 <prgn>adduser</prgn> will check for the existence of
5891 the user or group, and if necessary choose an unused
5892 id based on the ranges specified in
5893 <file>adduser.conf</file>.
5897 <tag>1000-59999:</tag>
5900 Dynamically allocated user accounts. By default
5901 <prgn>adduser</prgn> will choose UIDs and GIDs for
5902 user accounts in this range, though
5903 <file>adduser.conf</file> may be used to modify this
5908 <tag>60000-64999:</tag>
5911 Globally allocated by the Debian project, but only
5912 created on demand. The ids are allocated centrally
5913 and statically, but the actual accounts are only
5914 created on users' systems on demand.
5918 These ids are for packages which are obscure or
5919 which require many statically-allocated ids. These
5920 packages should check for and create the accounts in
5921 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5922 <prgn>adduser</prgn> if it has this facility) if
5923 necessary. Packages which are likely to require
5924 further allocations should have a "hole" left after
5925 them in the allocation, to give them room to
5930 <tag>65000-65533:</tag>
5938 User <tt>nobody</tt>. The corresponding gid refers
5939 to the group <tt>nogroup</tt>.
5946 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5947 not</em> be used, because it is the error return
5956 <sect id="sysvinit">
5957 <heading>System run levels and <file>init.d</file> scripts</heading>
5959 <sect1 id="/etc/init.d">
5960 <heading>Introduction</heading>
5963 The <file>/etc/init.d</file> directory contains the scripts
5964 executed by <prgn>init</prgn> at boot time and when the
5965 init state (or "runlevel") is changed (see <manref
5966 name="init" section="8">).
5970 There are at least two different, yet functionally
5971 equivalent, ways of handling these scripts. For the sake
5972 of simplicity, this document describes only the symbolic
5973 link method. However, it must not be assumed by maintainer
5974 scripts that this method is being used, and any automated
5975 manipulation of the various runlevel behaviors by
5976 maintainer scripts must be performed using
5977 <prgn>update-rc.d</prgn> as described below and not by
5978 manually installing or removing symlinks. For information
5979 on the implementation details of the other method,
5980 implemented in the <tt>file-rc</tt> package, please refer
5981 to the documentation of that package.
5985 These scripts are referenced by symbolic links in the
5986 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5987 runlevels, <prgn>init</prgn> looks in the directory
5988 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5989 execute, where <tt><var>n</var></tt> is the runlevel that
5990 is being changed to, or <tt>S</tt> for the boot-up
5995 The names of the links all have the form
5996 <file>S<var>mm</var><var>script</var></file> or
5997 <file>K<var>mm</var><var>script</var></file> where
5998 <var>mm</var> is a two-digit number and <var>script</var>
5999 is the name of the script (this should be the same as the
6000 name of the actual script in <file>/etc/init.d</file>).
6004 When <prgn>init</prgn> changes runlevel first the targets
6005 of the links whose names start with a <tt>K</tt> are
6006 executed, each with the single argument <tt>stop</tt>,
6007 followed by the scripts prefixed with an <tt>S</tt>, each
6008 with the single argument <tt>start</tt>. (The links are
6009 those in the <file>/etc/rc<var>n</var>.d</file> directory
6010 corresponding to the new runlevel.) The <tt>K</tt> links
6011 are responsible for killing services and the <tt>S</tt>
6012 link for starting services upon entering the runlevel.
6016 For example, if we are changing from runlevel 2 to
6017 runlevel 3, init will first execute all of the <tt>K</tt>
6018 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
6019 all of the <tt>S</tt> prefixed scripts in that directory.
6020 The links starting with <tt>K</tt> will cause the
6021 referred-to file to be executed with an argument of
6022 <tt>stop</tt>, and the <tt>S</tt> links with an argument
6027 The two-digit number <var>mm</var> is used to determine
6028 the order in which to run the scripts: low-numbered links
6029 have their scripts run first. For example, the
6030 <tt>K20</tt> scripts will be executed before the
6031 <tt>K30</tt> scripts. This is used when a certain service
6032 must be started before another. For example, the name
6033 server <prgn>bind</prgn> might need to be started before
6034 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
6035 can set up its access lists. In this case, the script
6036 that starts <prgn>bind</prgn> would have a lower number
6037 than the script that starts <prgn>inn</prgn> so that it
6039 <example compact="compact">
6046 The two runlevels 0 (halt) and 6 (reboot) are slightly
6047 different. In these runlevels, the links with an
6048 <tt>S</tt> prefix are still called after those with a
6049 <tt>K</tt> prefix, but they too are called with the single
6050 argument <tt>stop</tt>.
6054 <sect1 id="writing-init">
6055 <heading>Writing the scripts</heading>
6058 Packages that include daemons for system services should
6059 place scripts in <file>/etc/init.d</file> to start or stop
6060 services at boot time or during a change of runlevel.
6061 These scripts should be named
6062 <file>/etc/init.d/<var>package</var></file>, and they should
6063 accept one argument, saying what to do:
6066 <tag><tt>start</tt></tag>
6067 <item>start the service,</item>
6069 <tag><tt>stop</tt></tag>
6070 <item>stop the service,</item>
6072 <tag><tt>restart</tt></tag>
6073 <item>stop and restart the service if it's already running,
6074 otherwise start the service</item>
6076 <tag><tt>reload</tt></tag>
6077 <item><p>cause the configuration of the service to be
6078 reloaded without actually stopping and restarting
6081 <tag><tt>force-reload</tt></tag>
6082 <item>cause the configuration to be reloaded if the
6083 service supports this, otherwise restart the
6087 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
6088 <tt>force-reload</tt> options should be supported by all
6089 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
6094 The <file>init.d</file> scripts must ensure that they will
6095 behave sensibly (i.e., returning success and not starting
6096 multiple copies of a service) if invoked with <tt>start</tt>
6097 when the service is already running, or with <tt>stop</tt>
6098 when it isn't, and that they don't kill unfortunately-named
6099 user processes. The best way to achieve this is usually to
6100 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
6105 Be careful of using <tt>set -e</tt> in <file>init.d</file>
6106 scripts. Writing correct <file>init.d</file> scripts requires
6107 accepting various error exit statuses when daemons are already
6108 running or already stopped without aborting
6109 the <file>init.d</file> script, and common <file>init.d</file>
6110 function libraries are not safe to call with <tt>set -e</tt>
6112 <tt>/lib/lsb/init-functions</tt>, which assists in writing
6113 LSB-compliant init scripts, may fail if <tt>set -e</tt> is
6114 in effect and echoing status messages to the console fails,
6116 </footnote>. For <tt>init.d</tt> scripts, it's often easier
6117 to not use <tt>set -e</tt> and instead check the result of
6118 each command separately.
6122 If a service reloads its configuration automatically (as
6123 in the case of <prgn>cron</prgn>, for example), the
6124 <tt>reload</tt> option of the <file>init.d</file> script
6125 should behave as if the configuration has been reloaded
6130 The <file>/etc/init.d</file> scripts must be treated as
6131 configuration files, either (if they are present in the
6132 package, that is, in the .deb file) by marking them as
6133 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
6134 by managing them correctly in the maintainer scripts (see
6135 <ref id="config-files">). This is important since we want
6136 to give the local system administrator the chance to adapt
6137 the scripts to the local system, e.g., to disable a
6138 service without de-installing the package, or to specify
6139 some special command line options when starting a service,
6140 while making sure their changes aren't lost during the next
6145 These scripts should not fail obscurely when the
6146 configuration files remain but the package has been
6147 removed, as configuration files remain on the system after
6148 the package has been removed. Only when <prgn>dpkg</prgn>
6149 is executed with the <tt>--purge</tt> option will
6150 configuration files be removed. In particular, as the
6151 <file>/etc/init.d/<var>package</var></file> script itself is
6152 usually a <tt>conffile</tt>, it will remain on the system
6153 if the package is removed but not purged. Therefore, you
6154 should include a <tt>test</tt> statement at the top of the
6156 <example compact="compact">
6157 test -f <var>program-executed-later-in-script</var> || exit 0
6162 Often there are some variables in the <file>init.d</file>
6163 scripts whose values control the behavior of the scripts,
6164 and which a system administrator is likely to want to
6165 change. As the scripts themselves are frequently
6166 <tt>conffile</tt>s, modifying them requires that the
6167 administrator merge in their changes each time the package
6168 is upgraded and the <tt>conffile</tt> changes. To ease
6169 the burden on the system administrator, such configurable
6170 values should not be placed directly in the script.
6171 Instead, they should be placed in a file in
6172 <file>/etc/default</file>, which typically will have the same
6173 base name as the <file>init.d</file> script. This extra file
6174 should be sourced by the script when the script runs. It
6175 must contain only variable settings and comments in SUSv3
6176 <prgn>sh</prgn> format. It may either be a
6177 <tt>conffile</tt> or a configuration file maintained by
6178 the package maintainer scripts. See <ref id="config-files">
6183 To ensure that vital configurable values are always
6184 available, the <file>init.d</file> script should set default
6185 values for each of the shell variables it uses, either
6186 before sourcing the <file>/etc/default/</file> file or
6187 afterwards using something like the <tt>:
6188 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6189 script must behave sensibly and not fail if the
6190 <file>/etc/default</file> file is deleted.
6194 <file>/var/run</file> and <file>/var/lock</file> may be mounted
6195 as temporary filesystems<footnote>
6196 For example, using the <tt>RAMRUN</tt> and <tt>RAMLOCK</tt>
6197 options in <file>/etc/default/rcS</file>.
6198 </footnote>, so the <file>init.d</file> scripts must handle this
6199 correctly. This will typically amount to creating any required
6200 subdirectories dynamically when the <file>init.d</file> script
6201 is run, rather than including them in the package and relying on
6202 <prgn>dpkg</prgn> to create them.
6207 <heading>Interfacing with the initscript system</heading>
6210 Maintainers should use the abstraction layer provided by
6211 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6212 programs to deal with initscripts in their packages'
6213 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6214 and <prgn>postrm</prgn>.
6218 Directly managing the /etc/rc?.d links and directly
6219 invoking the <file>/etc/init.d/</file> initscripts should
6220 be done only by packages providing the initscript
6221 subsystem (such as <prgn>sysv-rc</prgn> and
6222 <prgn>file-rc</prgn>).
6226 <heading>Managing the links</heading>
6229 The program <prgn>update-rc.d</prgn> is provided for
6230 package maintainers to arrange for the proper creation and
6231 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6232 or their functional equivalent if another method is being
6233 used. This may be used by maintainers in their packages'
6234 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6238 You must not include any <file>/etc/rc<var>n</var>.d</file>
6239 symbolic links in the actual archive or manually create or
6240 remove the symbolic links in maintainer scripts; you must
6241 use the <prgn>update-rc.d</prgn> program instead. (The
6242 former will fail if an alternative method of maintaining
6243 runlevel information is being used.) You must not include
6244 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6245 in the archive either. (Only the <tt>sysvinit</tt>
6250 By default <prgn>update-rc.d</prgn> will start services in
6251 each of the multi-user state runlevels (2, 3, 4, and 5)
6252 and stop them in the halt runlevel (0), the single-user
6253 runlevel (1) and the reboot runlevel (6). The system
6254 administrator will have the opportunity to customize
6255 runlevels by simply adding, moving, or removing the
6256 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6257 symbolic links are being used, or by modifying
6258 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6263 To get the default behavior for your package, put in your
6264 <prgn>postinst</prgn> script
6265 <example compact="compact">
6266 update-rc.d <var>package</var> defaults
6268 and in your <prgn>postrm</prgn>
6269 <example compact="compact">
6270 if [ "$1" = purge ]; then
6271 update-rc.d <var>package</var> remove
6273 </example>. Note that if your package changes runlevels
6274 or priority, you may have to remove and recreate the links,
6275 since otherwise the old links may persist. Refer to the
6276 documentation of <prgn>update-rc.d</prgn>.
6280 This will use a default sequence number of 20. If it does
6281 not matter when or in which order the <file>init.d</file>
6282 script is run, use this default. If it does, then you
6283 should talk to the maintainer of the <prgn>sysvinit</prgn>
6284 package or post to <tt>debian-devel</tt>, and they will
6285 help you choose a number.
6289 For more information about using <tt>update-rc.d</tt>,
6290 please consult its man page <manref name="update-rc.d"
6296 <heading>Running initscripts</heading>
6298 The program <prgn>invoke-rc.d</prgn> is provided to make
6299 it easier for package maintainers to properly invoke an
6300 initscript, obeying runlevel and other locally-defined
6301 constraints that might limit a package's right to start,
6302 stop and otherwise manage services. This program may be
6303 used by maintainers in their packages' scripts.
6307 The package maintainer scripts must use
6308 <prgn>invoke-rc.d</prgn> to invoke the
6309 <file>/etc/init.d/*</file> initscripts, instead of
6310 calling them directly.
6314 By default, <prgn>invoke-rc.d</prgn> will pass any
6315 action requests (start, stop, reload, restart...) to the
6316 <file>/etc/init.d</file> script, filtering out requests
6317 to start or restart a service out of its intended
6322 Most packages will simply need to change:
6323 <example compact="compact">/etc/init.d/<package>
6324 <action></example> in their <prgn>postinst</prgn>
6325 and <prgn>prerm</prgn> scripts to:
6326 <example compact="compact">
6327 if which invoke-rc.d >/dev/null 2>&1; then
6328 invoke-rc.d <var>package</var> <action>
6330 /etc/init.d/<var>package</var> <action>
6336 A package should register its initscript services using
6337 <prgn>update-rc.d</prgn> before it tries to invoke them
6338 using <prgn>invoke-rc.d</prgn>. Invocation of
6339 unregistered services may fail.
6343 For more information about using
6344 <prgn>invoke-rc.d</prgn>, please consult its man page
6345 <manref name="invoke-rc.d" section="8">.
6351 <heading>Boot-time initialization</heading>
6354 There used to be another directory, <file>/etc/rc.boot</file>,
6355 which contained scripts which were run once per machine
6356 boot. This has been deprecated in favour of links from
6357 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6358 described in <ref id="/etc/init.d">. Packages must not
6359 place files in <file>/etc/rc.boot</file>.
6364 <heading>Example</heading>
6367 An example on which you can base your
6368 <file>/etc/init.d</file> scripts is found in
6369 <file>/etc/init.d/skeleton</file>.
6376 <heading>Console messages from <file>init.d</file> scripts</heading>
6379 This section describes the formats to be used for messages
6380 written to standard output by the <file>/etc/init.d</file>
6381 scripts. The intent is to improve the consistency of
6382 Debian's startup and shutdown look and feel. For this
6383 reason, please look very carefully at the details. We want
6384 the messages to have the same format in terms of wording,
6385 spaces, punctuation and case of letters.
6389 Here is a list of overall rules that should be used for
6390 messages generated by <file>/etc/init.d</file> scripts.
6396 The message should fit in one line (fewer than 80
6397 characters), start with a capital letter and end with
6398 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6402 If the script is performing some time consuming task in
6403 the background (not merely starting or stopping a
6404 program, for instance), an ellipsis (three dots:
6405 <tt>...</tt>) should be output to the screen, with no
6406 leading or tailing whitespace or line feeds.
6410 The messages should appear as if the computer is telling
6411 the user what it is doing (politely :-), but should not
6412 mention "it" directly. For example, instead of:
6413 <example compact="compact">
6414 I'm starting network daemons: nfsd mountd.
6416 the message should say
6417 <example compact="compact">
6418 Starting network daemons: nfsd mountd.
6425 <tt>init.d</tt> script should use the following standard
6426 message formats for the situations enumerated below.
6432 <p>When daemons are started</p>
6435 If the script starts one or more daemons, the output
6436 should look like this (a single line, no leading
6438 <example compact="compact">
6439 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6441 The <var>description</var> should describe the
6442 subsystem the daemon or set of daemons are part of,
6443 while <var>daemon-1</var> up to <var>daemon-n</var>
6444 denote each daemon's name (typically the file name of
6449 For example, the output of <file>/etc/init.d/lpd</file>
6451 <example compact="compact">
6452 Starting printer spooler: lpd.
6457 This can be achieved by saying
6458 <example compact="compact">
6459 echo -n "Starting printer spooler: lpd"
6460 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6463 in the script. If there are more than one daemon to
6464 start, the output should look like this:
6465 <example compact="compact">
6466 echo -n "Starting remote file system services:"
6467 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6468 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6469 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6472 This makes it possible for the user to see what is
6473 happening and when the final daemon has been started.
6474 Care should be taken in the placement of white spaces:
6475 in the example above the system administrators can
6476 easily comment out a line if they don't want to start
6477 a specific daemon, while the displayed message still
6483 <p>When a system parameter is being set</p>
6486 If you have to set up different system parameters
6487 during the system boot, you should use this format:
6488 <example compact="compact">
6489 Setting <var>parameter</var> to "<var>value</var>".
6494 You can use a statement such as the following to get
6496 <example compact="compact">
6497 echo "Setting DNS domainname to \"$domainname\"."
6502 Note that the same symbol (<tt>"</tt>) <!-- " --> is used
6503 for the left and right quotation marks. A grave accent
6504 (<tt>`</tt>) is not a quote character; neither is an
6505 apostrophe (<tt>'</tt>).
6510 <p>When a daemon is stopped or restarted</p>
6513 When you stop or restart a daemon, you should issue a
6514 message identical to the startup message, except that
6515 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6516 or <tt>Restarting</tt> respectively.
6520 For example, stopping the printer daemon will look like
6522 <example compact="compact">
6523 Stopping printer spooler: lpd.
6529 <p>When something is executed</p>
6532 There are several examples where you have to run a
6533 program at system startup or shutdown to perform a
6534 specific task, for example, setting the system's clock
6535 using <prgn>netdate</prgn> or killing all processes
6536 when the system shuts down. Your message should look
6538 <example compact="compact">
6539 Doing something very useful...done.
6541 You should print the <tt>done.</tt> immediately after
6542 the job has been completed, so that the user is
6543 informed why they have to wait. You can get this
6545 <example compact="compact">
6546 echo -n "Doing something very useful..."
6555 <p>When the configuration is reloaded</p>
6558 When a daemon is forced to reload its configuration
6559 files you should use the following format:
6560 <example compact="compact">
6561 Reloading <var>description</var> configuration...done.
6563 where <var>description</var> is the same as in the
6564 daemon starting message.
6572 <heading>Cron jobs</heading>
6575 Packages must not modify the configuration file
6576 <file>/etc/crontab</file>, and they must not modify the files in
6577 <file>/var/spool/cron/crontabs</file>.</p>
6580 If a package wants to install a job that has to be executed
6581 via cron, it should place a file with the name of the
6582 package in one or more of the following directories:
6583 <example compact="compact">
6589 As these directory names imply, the files within them are
6590 executed on an hourly, daily, weekly, or monthly basis,
6591 respectively. The exact times are listed in
6592 <file>/etc/crontab</file>.</p>
6595 All files installed in any of these directories must be
6596 scripts (e.g., shell scripts or Perl scripts) so that they
6597 can easily be modified by the local system administrator.
6598 In addition, they must be treated as configuration files.
6602 If a certain job has to be executed at some other frequency or
6603 at a specific time, the package should install a file
6604 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6605 same syntax as <file>/etc/crontab</file> and is processed by
6606 <prgn>cron</prgn> automatically. The file must also be
6607 treated as a configuration file. (Note that entries in the
6608 <file>/etc/cron.d</file> directory are not handled by
6609 <prgn>anacron</prgn>. Thus, you should only use this
6610 directory for jobs which may be skipped if the system is not
6613 Unlike <file>crontab</file> files described in the IEEE Std
6614 1003.1-2008 (POSIX.1) available from
6615 <url id="http://www.opengroup.org/onlinepubs/9699919799/"
6616 name="The Open Group">, the files in
6617 <file>/etc/cron.d</file> and the file
6618 <file>/etc/crontab</file> have seven fields; namely:
6620 <item>Minute [0,59]</item>
6621 <item>Hour [0,23]</item>
6622 <item>Day of the month [1,31]</item>
6623 <item>Month of the year [1,12]</item>
6624 <item>Day of the week ([0,6] with 0=Sunday)</item>
6625 <item>Username</item>
6626 <item>Command to be run</item>
6628 Ranges of numbers are allowed. Ranges are two numbers
6629 separated with a hyphen. The specified range is inclusive.
6630 Lists are allowed. A list is a set of numbers (or ranges)
6631 separated by commas. Step values can be used in conjunction
6636 The scripts or <tt>crontab</tt> entries in these directories should
6637 check if all necessary programs are installed before they
6638 try to execute them. Otherwise, problems will arise when a
6639 package was removed but not purged since configuration files
6640 are kept on the system in this situation.
6644 Any <tt>cron</tt> daemon must provide
6645 <file>/usr/bin/crontab</file> and support normal
6646 <tt>crontab</tt> entries as specified in POSIX. The daemon
6647 must also support names for days and months, ranges, and
6648 step values. It has to support <file>/etc/crontab</file>,
6649 and correctly execute the scripts in
6650 <file>/etc/cron.d</file>. The daemon must also correctly
6652 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>.
6657 <heading>Menus</heading>
6660 The Debian <tt>menu</tt> package provides a standard
6661 interface between packages providing applications and
6662 <em>menu programs</em> (either X window managers or
6663 text-based menu programs such as <prgn>pdmenu</prgn>).
6667 All packages that provide applications that need not be
6668 passed any special command line arguments for normal
6669 operation should register a menu entry for those
6670 applications, so that users of the <tt>menu</tt> package
6671 will automatically get menu entries in their window
6672 managers, as well in shells like <tt>pdmenu</tt>.
6676 Menu entries should follow the current menu policy.
6680 The menu policy can be found in the <tt>menu-policy</tt>
6681 files in the <tt>debian-policy</tt> package.
6682 It is also available from the Debian web mirrors at
6683 <tt><url name="/doc/packaging-manuals/menu-policy/"
6684 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6688 Please also refer to the <em>Debian Menu System</em>
6689 documentation that comes with the <package>menu</package>
6690 package for information about how to register your
6696 <heading>Multimedia handlers</heading>
6699 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6700 is a mechanism for encoding files and data streams and
6701 providing meta-information about them, in particular their
6702 type (e.g. audio or video) and format (e.g. PNG, HTML,
6707 Registration of MIME type handlers allows programs like mail
6708 user agents and web browsers to invoke these handlers to
6709 view, edit or display MIME types they don't support directly.
6713 Packages which provide the ability to view/show/play,
6714 compose, edit or print MIME types should register themselves
6715 as such following the current MIME support policy.
6719 The MIME support policy can be found in the <tt>mime-policy</tt>
6720 files in the <tt>debian-policy</tt> package.
6721 It is also available from the Debian web mirrors at
6722 <tt><url name="/doc/packaging-manuals/mime-policy/"
6723 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6729 <heading>Keyboard configuration</heading>
6732 To achieve a consistent keyboard configuration so that all
6733 applications interpret a keyboard event the same way, all
6734 programs in the Debian distribution must be configured to
6735 comply with the following guidelines.
6739 The following keys must have the specified interpretations:
6742 <tag><tt><--</tt></tag>
6743 <item>delete the character to the left of the cursor</item>
6745 <tag><tt>Delete</tt></tag>
6746 <item>delete the character to the right of the cursor</item>
6748 <tag><tt>Control+H</tt></tag>
6749 <item>emacs: the help prefix</item>
6752 The interpretation of any keyboard events should be
6753 independent of the terminal that is used, be it a virtual
6754 console, an X terminal emulator, an rlogin/telnet session,
6759 The following list explains how the different programs
6760 should be set up to achieve this:
6766 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6770 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6774 X translations are set up to make
6775 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6776 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6777 is the vt220 escape code for the "delete character"
6778 key). This must be done by loading the X resources
6779 using <prgn>xrdb</prgn> on all local X displays, not
6780 using the application defaults, so that the
6781 translation resources used correspond to the
6782 <prgn>xmodmap</prgn> settings.
6786 The Linux console is configured to make
6787 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6788 generate <tt>ESC [ 3 ~</tt>.
6792 X applications are configured so that <tt><</tt>
6793 deletes left, and <tt>Delete</tt> deletes right. Motif
6794 applications already work like this.
6798 Terminals should have <tt>stty erase ^?</tt> .
6802 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6803 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6804 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6808 Emacs is programmed to map <tt>KB_Backspace</tt> or
6809 the <tt>stty erase</tt> character to
6810 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6811 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6812 <tt>^H</tt> to <tt>help</tt> as always.
6816 Other applications use the <tt>stty erase</tt>
6817 character and <tt>kdch1</tt> for the two delete keys,
6818 with ASCII DEL being "delete previous character" and
6819 <tt>kdch1</tt> being "delete character under
6827 This will solve the problem except for the following
6834 Some terminals have a <tt><--</tt> key that cannot
6835 be made to produce anything except <tt>^H</tt>. On
6836 these terminals Emacs help will be unavailable on
6837 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6838 character takes precedence in Emacs, and has been set
6839 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6840 available) can be used instead.
6844 Some operating systems use <tt>^H</tt> for <tt>stty
6845 erase</tt>. However, modern telnet versions and all
6846 rlogin versions propagate <tt>stty</tt> settings, and
6847 almost all UNIX versions honour <tt>stty erase</tt>.
6848 Where the <tt>stty</tt> settings are not propagated
6849 correctly, things can be made to work by using
6850 <tt>stty</tt> manually.
6854 Some systems (including previous Debian versions) use
6855 <prgn>xmodmap</prgn> to arrange for both
6856 <tt><--</tt> and <tt>Delete</tt> to generate
6857 <tt>KB_Delete</tt>. We can change the behavior of
6858 their X clients using the same X resources that we use
6859 to do it for our own clients, or configure our clients
6860 using their resources when things are the other way
6861 around. On displays configured like this
6862 <tt>Delete</tt> will not work, but <tt><--</tt>
6867 Some operating systems have different <tt>kdch1</tt>
6868 settings in their <tt>terminfo</tt> database for
6869 <tt>xterm</tt> and others. On these systems the
6870 <tt>Delete</tt> key will not work correctly when you
6871 log in from a system conforming to our policy, but
6872 <tt><--</tt> will.
6879 <heading>Environment variables</heading>
6882 A program must not depend on environment variables to get
6883 reasonable defaults. (That's because these environment
6884 variables would have to be set in a system-wide
6885 configuration file like <file>/etc/profile</file>, which is not
6886 supported by all shells.)
6890 If a program usually depends on environment variables for its
6891 configuration, the program should be changed to fall back to
6892 a reasonable default configuration if these environment
6893 variables are not present. If this cannot be done easily
6894 (e.g., if the source code of a non-free program is not
6895 available), the program must be replaced by a small
6896 "wrapper" shell script which sets the environment variables
6897 if they are not already defined, and calls the original program.
6901 Here is an example of a wrapper script for this purpose:
6903 <example compact="compact">
6905 BAR=${BAR:-/var/lib/fubar}
6907 exec /usr/lib/foo/foo "$@"
6912 Furthermore, as <file>/etc/profile</file> is a configuration
6913 file of the <prgn>base-files</prgn> package, other packages must
6914 not put any environment variables or other commands into that
6919 <sect id="doc-base">
6920 <heading>Registering Documents using doc-base</heading>
6923 The <package>doc-base</package> package implements a
6924 flexible mechanism for handling and presenting
6925 documentation. The recommended practice is for every Debian
6926 package that provides online documentation (other than just
6927 manual pages) to register these documents with
6928 <package>doc-base</package> by installing a
6929 <package>doc-base</package> control file via the
6930 <prgn/install-docs/ script at installation time and
6931 de-register the manuals again when the package is removed.
6934 Please refer to the documentation that comes with the
6935 <package>doc-base</package> package for information and
6944 <heading>Files</heading>
6947 <heading>Binaries</heading>
6950 Two different packages must not install programs with
6951 different functionality but with the same filenames. (The
6952 case of two programs having the same functionality but
6953 different implementations is handled via "alternatives" or
6954 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6955 <ref id="conflicts"> respectively.) If this case happens,
6956 one of the programs must be renamed. The maintainers should
6957 report this to the <tt>debian-devel</tt> mailing list and
6958 try to find a consensus about which program will have to be
6959 renamed. If a consensus cannot be reached, <em>both</em>
6960 programs must be renamed.
6964 By default, when a package is being built, any binaries
6965 created should include debugging information, as well as
6966 being compiled with optimization. You should also turn on
6967 as many reasonable compilation warnings as possible; this
6968 makes life easier for porters, who can then look at build
6969 logs for possible problems. For the C programming language,
6970 this means the following compilation parameters should be
6972 <example compact="compact">
6974 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6976 INSTALL = install -s # (or use strip on the files in debian/tmp)
6981 Note that by default all installed binaries should be stripped,
6982 either by using the <tt>-s</tt> flag to
6983 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6984 the binaries after they have been copied into
6985 <file>debian/tmp</file> but before the tree is made into a
6990 Although binaries in the build tree should be compiled with
6991 debugging information by default, it can often be difficult to
6992 debug programs if they are also subjected to compiler
6993 optimization. For this reason, it is recommended to support the
6994 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
6995 (see <ref id="debianrules-options">). This variable can contain
6996 several flags to change how a package is compiled and built.
7000 It is up to the package maintainer to decide what
7001 compilation options are best for the package. Certain
7002 binaries (such as computationally-intensive programs) will
7003 function better with certain flags (<tt>-O3</tt>, for
7004 example); feel free to use them. Please use good judgment
7005 here. Don't use flags for the sake of it; only use them
7006 if there is good reason to do so. Feel free to override
7007 the upstream author's ideas about which compilation
7008 options are best: they are often inappropriate for our
7014 <sect id="libraries">
7015 <heading>Libraries</heading>
7018 If the package is <strong>architecture: any</strong>, then
7019 the shared library compilation and linking flags must have
7020 <tt>-fPIC</tt>, or the package shall not build on some of
7021 the supported architectures<footnote>
7023 If you are using GCC, <tt>-fPIC</tt> produces code with
7024 relocatable position independent code, which is required for
7025 most architectures to create a shared library, with i386 and
7026 perhaps some others where non position independent code is
7027 permitted in a shared library.
7030 Position independent code may have a performance penalty,
7031 especially on <tt>i386</tt>. However, in most cases the
7032 speed penalty must be measured against the memory wasted on
7033 the few architectures where non position independent code is
7036 </footnote>. Any exception to this rule must be discussed on
7037 the mailing list <em>debian-devel@lists.debian.org</em>, and
7038 a rough consensus obtained. The reasons for not compiling
7039 with <tt>-fPIC</tt> flag must be recorded in the file
7040 <tt>README.Debian</tt>, and care must be taken to either
7041 restrict the architecture or arrange for <tt>-fPIC</tt> to
7042 be used on architectures where it is required.<footnote>
7044 Some of the reasons why this might be required is if the
7045 library contains hand crafted assembly code that is not
7046 relocatable, the speed penalty is excessive for compute
7047 intensive libs, and similar reasons.
7052 As to the static libraries, the common case is not to have
7053 relocatable code, since there is no benefit, unless in specific
7054 cases; therefore the static version must not be compiled
7055 with the <tt>-fPIC</tt> flag. Any exception to this rule
7056 should be discussed on the mailing list
7057 <em>debian-devel@lists.debian.org</em>, and the reasons for
7058 compiling with the <tt>-fPIC</tt> flag must be recorded in
7059 the file <tt>README.Debian</tt>. <footnote>
7061 Some of the reasons for linking static libraries with
7062 the <tt>-fPIC</tt> flag are if, for example, one needs a
7063 Perl API for a library that is under rapid development,
7064 and has an unstable API, so shared libraries are
7065 pointless at this phase of the library's development. In
7066 that case, since Perl needs a library with relocatable
7067 code, it may make sense to create a static library with
7068 relocatable code. Another reason cited is if you are
7069 distilling various libraries into a common shared
7070 library, like <tt>mklibs</tt> does in the Debian
7076 In other words, if both a shared and a static library is
7077 being built, each source unit (<tt>*.c</tt>, for example,
7078 for C files) will need to be compiled twice, for the normal
7082 You must specify the gcc option <tt>-D_REENTRANT</tt>
7083 when building a library (either static or shared) to make
7084 the library compatible with LinuxThreads.
7088 Although not enforced by the build tools, shared libraries
7089 must be linked against all libraries that they use symbols from
7090 in the same way that binaries are. This ensures the correct
7091 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
7092 system and guarantees that all libraries can be safely opened
7093 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
7094 option <tt>-Wl,-z,defs</tt> when building a shared library.
7095 Since this option enforces symbol resolution at build time,
7096 a missing library reference will be caught early as a fatal
7101 All installed shared libraries should be stripped with
7102 <example compact="compact">
7103 strip --strip-unneeded <var>your-lib</var>
7105 (The option <tt>--strip-unneeded</tt> makes
7106 <prgn>strip</prgn> remove only the symbols which aren't
7107 needed for relocation processing.) Shared libraries can
7108 function perfectly well when stripped, since the symbols for
7109 dynamic linking are in a separate part of the ELF object
7111 You might also want to use the options
7112 <tt>--remove-section=.comment</tt> and
7113 <tt>--remove-section=.note</tt> on both shared libraries
7114 and executables, and <tt>--strip-debug</tt> on static
7120 Note that under some circumstances it may be useful to
7121 install a shared library unstripped, for example when
7122 building a separate package to support debugging.
7126 Shared object files (often <file>.so</file> files) that are not
7127 public libraries, that is, they are not meant to be linked
7128 to by third party executables (binaries of other packages),
7129 should be installed in subdirectories of the
7130 <file>/usr/lib</file> directory. Such files are exempt from the
7131 rules that govern ordinary shared libraries, except that
7132 they must not be installed executable and should be
7134 A common example are the so-called "plug-ins",
7135 internal shared objects that are dynamically loaded by
7136 programs using <manref name="dlopen" section="3">.
7141 An ever increasing number of packages are using
7142 <prgn>libtool</prgn> to do their linking. The latest GNU
7143 libtools (>= 1.3a) can take advantage of the metadata in the
7144 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
7145 files). The main advantage of <prgn>libtool</prgn>'s
7146 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
7147 store and subsequently access metadata with respect to the
7148 libraries it builds. <prgn>libtool</prgn> will search for
7149 those files, which contain a lot of useful information about
7150 a library (such as library dependency information for static
7151 linking). Also, they're <em>essential</em> for programs
7152 using <tt>libltdl</tt>.<footnote>
7153 Although <prgn>libtool</prgn> is fully capable of
7154 linking against shared libraries which don't have
7155 <tt>.la</tt> files, as it is a mere shell script it can
7156 add considerably to the build time of a
7157 <prgn>libtool</prgn>-using package if that shell script
7158 has to derive all this information from first principles
7159 for each library every time it is linked. With the
7160 advent of <prgn>libtool</prgn> version 1.4 (and to a
7161 lesser extent <prgn>libtool</prgn> version 1.3), the
7162 <file>.la</file> files also store information about
7163 inter-library dependencies which cannot necessarily be
7164 derived after the <file>.la</file> file is deleted.
7169 Packages that use <prgn>libtool</prgn> to create shared
7170 libraries should include the <file>.la</file> files in the
7171 <tt>-dev</tt> package, unless the package relies on
7172 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
7173 the <tt>.la</tt> files must go in the run-time library
7178 You must make sure that you use only released versions of
7179 shared libraries to build your packages; otherwise other
7180 users will not be able to run your binaries
7181 properly. Producing source packages that depend on
7182 unreleased compilers is also usually a bad
7189 <heading>Shared libraries</heading>
7191 This section has moved to <ref id="sharedlibs">.
7197 <heading>Scripts</heading>
7200 All command scripts, including the package maintainer
7201 scripts inside the package and used by <prgn>dpkg</prgn>,
7202 should have a <tt>#!</tt> line naming the shell to be used
7207 In the case of Perl scripts this should be
7208 <tt>#!/usr/bin/perl</tt>.
7212 When scripts are installed into a directory in the system
7213 PATH, the script name should not include an extension such
7214 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7215 language currently used to implement it.
7218 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>) other than
7219 <file>init.d</file> scripts should almost certainly start
7220 with <tt>set -e</tt> so that errors are detected.
7221 <file>init.d</file> scripts are something of a special case, due
7222 to how frequently they need to call commands that are allowed to
7223 fail, and it may instead be easier to check the exit status of
7224 commands directly. See <ref id="writing-init"> for more
7225 information about writing <file>init.d</file> scripts.
7228 Every script should use <tt>set -e</tt> or check the exit status
7229 of <em>every</em> command.
7232 Scripts may assume that <file>/bin/sh</file> implements the
7233 SUSv3 Shell Command Language<footnote>
7234 Single UNIX Specification, version 3, which is also IEEE
7235 1003.1-2004 (POSIX), and is available on the World Wide Web
7236 from <url id="http://www.unix.org/version3/online.html"
7237 name="The Open Group"> after free
7238 registration.</footnote>
7239 plus the following additional features not mandated by
7241 These features are in widespread use in the Linux community
7242 and are implemented in all of bash, dash, and ksh, the most
7243 common shells users may wish to use as <file>/bin/sh</file>.
7246 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7247 must not generate a newline.</item>
7248 <item><tt>test</tt>, if implemented as a shell built-in, must
7249 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7251 <item><tt>local</tt> to create a scoped variable must be
7252 supported, including listing multiple variables in a single
7253 local command and assigning a value to a variable at the
7254 same time as localizing it. <tt>local</tt> may or
7255 may not preserve the variable value from an outer scope if
7256 no assignment is present. Uses such as:
7260 # ... use a, b, c, d ...
7263 must be supported and must set the value of <tt>c</tt> to
7267 If a shell script requires non-SUSv3 features from the shell
7268 interpreter other than those listed above, the appropriate shell
7269 must be specified in the first line of the script (e.g.,
7270 <tt>#!/bin/bash</tt>) and the package must depend on the package
7271 providing the shell (unless the shell package is marked
7272 "Essential", as in the case of <prgn>bash</prgn>).
7276 You may wish to restrict your script to SUSv3 features plus the
7277 above set when possible so that it may use <file>/bin/sh</file>
7278 as its interpreter. If your script works with <prgn>dash</prgn>
7279 (originally called <prgn>ash</prgn>), it probably complies with
7280 the above requirements, but if you are in doubt, use
7281 <file>/bin/bash</file>.
7285 Perl scripts should check for errors when making any
7286 system calls, including <tt>open</tt>, <tt>print</tt>,
7287 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7291 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7292 scripting languages. See <em>Csh Programming Considered
7293 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7294 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7295 If an upstream package comes with <prgn>csh</prgn> scripts
7296 then you must make sure that they start with
7297 <tt>#!/bin/csh</tt> and make your package depend on the
7298 <prgn>c-shell</prgn> virtual package.
7302 Any scripts which create files in world-writeable
7303 directories (e.g., in <file>/tmp</file>) must use a
7304 mechanism which will fail atomically if a file with the same
7305 name already exists.
7309 The Debian base system provides the <prgn>tempfile</prgn>
7310 and <prgn>mktemp</prgn> utilities for use by scripts for
7317 <heading>Symbolic links</heading>
7320 In general, symbolic links within a top-level directory
7321 should be relative, and symbolic links pointing from one
7322 top-level directory into another should be absolute. (A
7323 top-level directory is a sub-directory of the root
7324 directory <file>/</file>.)
7328 In addition, symbolic links should be specified as short as
7329 possible, i.e., link targets like <file>foo/../bar</file> are
7334 Note that when creating a relative link using
7335 <prgn>ln</prgn> it is not necessary for the target of the
7336 link to exist relative to the working directory you're
7337 running <prgn>ln</prgn> from, nor is it necessary to change
7338 directory to the directory where the link is to be made.
7339 Simply include the string that should appear as the target
7340 of the link (this will be a pathname relative to the
7341 directory in which the link resides) as the first argument
7346 For example, in your <prgn>Makefile</prgn> or
7347 <file>debian/rules</file>, you can do things like:
7348 <example compact="compact">
7349 ln -fs gcc $(prefix)/bin/cc
7350 ln -fs gcc debian/tmp/usr/bin/cc
7351 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7352 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7357 A symbolic link pointing to a compressed file should always
7358 have the same file extension as the referenced file. (For
7359 example, if a file <file>foo.gz</file> is referenced by a
7360 symbolic link, the filename of the link has to end with
7361 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7366 <heading>Device files</heading>
7369 Packages must not include device files or named pipes in the
7374 If a package needs any special device files that are not
7375 included in the base system, it must call
7376 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7377 after notifying the user<footnote>
7378 This notification could be done via a (low-priority)
7379 debconf message, or an echo (printf) statement.
7384 Packages must not remove any device files in the
7385 <prgn>postrm</prgn> or any other script. This is left to the
7386 system administrator.
7390 Debian uses the serial devices
7391 <file>/dev/ttyS*</file>. Programs using the old
7392 <file>/dev/cu*</file> devices should be changed to use
7393 <file>/dev/ttyS*</file>.
7397 Named pipes needed by the package must be created in
7398 the <prgn>postinst</prgn> script<footnote>
7399 It's better to use <prgn>mkfifo</prgn> rather
7400 than <prgn>mknod</prgn> to create named pipes so that
7401 automated checks for packages incorrectly creating device
7402 files with <prgn>mknod</prgn> won't have false positives.
7403 </footnote> and removed in
7404 the <prgn>prerm</prgn> or <prgn>postrm</prgn> script as
7409 <sect id="config-files">
7410 <heading>Configuration files</heading>
7413 <heading>Definitions</heading>
7417 <tag>configuration file</tag>
7419 A file that affects the operation of a program, or
7420 provides site- or host-specific information, or
7421 otherwise customizes the behavior of a program.
7422 Typically, configuration files are intended to be
7423 modified by the system administrator (if needed or
7424 desired) to conform to local policy or to provide
7425 more useful site-specific behavior.
7428 <tag><tt>conffile</tt></tag>
7430 A file listed in a package's <tt>conffiles</tt>
7431 file, and is treated specially by <prgn>dpkg</prgn>
7432 (see <ref id="configdetails">).
7438 The distinction between these two is important; they are
7439 not interchangeable concepts. Almost all
7440 <tt>conffile</tt>s are configuration files, but many
7441 configuration files are not <tt>conffiles</tt>.
7445 As noted elsewhere, <file>/etc/init.d</file> scripts,
7446 <file>/etc/default</file> files, scripts installed in
7447 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7448 configuration installed in <file>/etc/cron.d</file> must be
7449 treated as configuration files. In general, any script that
7450 embeds configuration information is de-facto a configuration
7451 file and should be treated as such.
7456 <heading>Location</heading>
7459 Any configuration files created or used by your package
7460 must reside in <file>/etc</file>. If there are several,
7461 consider creating a subdirectory of <file>/etc</file>
7462 named after your package.
7466 If your package creates or uses configuration files
7467 outside of <file>/etc</file>, and it is not feasible to modify
7468 the package to use <file>/etc</file> directly, put the files
7469 in <file>/etc</file> and create symbolic links to those files
7470 from the location that the package requires.
7475 <heading>Behavior</heading>
7478 Configuration file handling must conform to the following
7480 <list compact="compact">
7482 local changes must be preserved during a package
7486 configuration files must be preserved when the
7487 package is removed, and only deleted when the
7494 The easy way to achieve this behavior is to make the
7495 configuration file a <tt>conffile</tt>. This is
7496 appropriate only if it is possible to distribute a default
7497 version that will work for most installations, although
7498 some system administrators may choose to modify it. This
7499 implies that the default version will be part of the
7500 package distribution, and must not be modified by the
7501 maintainer scripts during installation (or at any other
7506 In order to ensure that local changes are preserved
7507 correctly, no package may contain or make hard links to
7508 conffiles.<footnote>
7509 Rationale: There are two problems with hard links.
7510 The first is that some editors break the link while
7511 editing one of the files, so that the two files may
7512 unwittingly become unlinked and different. The second
7513 is that <prgn>dpkg</prgn> might break the hard link
7514 while upgrading <tt>conffile</tt>s.
7519 The other way to do it is via the maintainer scripts. In
7520 this case, the configuration file must not be listed as a
7521 <tt>conffile</tt> and must not be part of the package
7522 distribution. If the existence of a file is required for
7523 the package to be sensibly configured it is the
7524 responsibility of the package maintainer to provide
7525 maintainer scripts which correctly create, update and
7526 maintain the file and remove it on purge. (See <ref
7527 id="maintainerscripts"> for more information.) These
7528 scripts must be idempotent (i.e., must work correctly if
7529 <prgn>dpkg</prgn> needs to re-run them due to errors
7530 during installation or removal), must cope with all the
7531 variety of ways <prgn>dpkg</prgn> can call maintainer
7532 scripts, must not overwrite or otherwise mangle the user's
7533 configuration without asking, must not ask unnecessary
7534 questions (particularly during upgrades), and must
7535 otherwise be good citizens.
7539 The scripts are not required to configure every possible
7540 option for the package, but only those necessary to get
7541 the package running on a given system. Ideally the
7542 sysadmin should not have to do any configuration other
7543 than that done (semi-)automatically by the
7544 <prgn>postinst</prgn> script.
7548 A common practice is to create a script called
7549 <file><var>package</var>-configure</file> and have the
7550 package's <prgn>postinst</prgn> call it if and only if the
7551 configuration file does not already exist. In certain
7552 cases it is useful for there to be an example or template
7553 file which the maintainer scripts use. Such files should
7554 be in <file>/usr/share/<var>package</var></file> or
7555 <file>/usr/lib/<var>package</var></file> (depending on whether
7556 they are architecture-independent or not). There should
7557 be symbolic links to them from
7558 <file>/usr/share/doc/<var>package</var>/examples</file> if
7559 they are examples, and should be perfectly ordinary
7560 <prgn>dpkg</prgn>-handled files (<em>not</em>
7561 configuration files).
7565 These two styles of configuration file handling must
7566 not be mixed, for that way lies madness:
7567 <prgn>dpkg</prgn> will ask about overwriting the file
7568 every time the package is upgraded.
7573 <heading>Sharing configuration files</heading>
7576 Packages which specify the same file as a
7577 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7578 with each other. (This is an instance of the general rule
7579 about not sharing files. Note that neither alternatives
7580 nor diversions are likely to be appropriate in this case;
7581 in particular, <prgn>dpkg</prgn> does not handle diverted
7582 <tt>conffile</tt>s well.)
7586 The maintainer scripts must not alter a <tt>conffile</tt>
7587 of <em>any</em> package, including the one the scripts
7592 If two or more packages use the same configuration file
7593 and it is reasonable for both to be installed at the same
7594 time, one of these packages must be defined as
7595 <em>owner</em> of the configuration file, i.e., it will be
7596 the package which handles that file as a configuration
7597 file. Other packages that use the configuration file must
7598 depend on the owning package if they require the
7599 configuration file to operate. If the other package will
7600 use the configuration file if present, but is capable of
7601 operating without it, no dependency need be declared.
7605 If it is desirable for two or more related packages to
7606 share a configuration file <em>and</em> for all of the
7607 related packages to be able to modify that configuration
7608 file, then the following should be done:
7609 <enumlist compact="compact">
7611 One of the related packages (the "owning" package)
7612 will manage the configuration file with maintainer
7613 scripts as described in the previous section.
7616 The owning package should also provide a program
7617 that the other packages may use to modify the
7621 The related packages must use the provided program
7622 to make any desired modifications to the
7623 configuration file. They should either depend on
7624 the core package to guarantee that the configuration
7625 modifier program is available or accept gracefully
7626 that they cannot modify the configuration file if it
7627 is not. (This is in addition to the fact that the
7628 configuration file may not even be present in the
7635 Sometimes it's appropriate to create a new package which
7636 provides the basic infrastructure for the other packages
7637 and which manages the shared configuration files. (The
7638 <tt>sgml-base</tt> package is a good example.)
7643 <heading>User configuration files ("dotfiles")</heading>
7646 The files in <file>/etc/skel</file> will automatically be
7647 copied into new user accounts by <prgn>adduser</prgn>.
7648 No other program should reference the files in
7649 <file>/etc/skel</file>.
7653 Therefore, if a program needs a dotfile to exist in
7654 advance in <file>$HOME</file> to work sensibly, that dotfile
7655 should be installed in <file>/etc/skel</file> and treated as a
7660 However, programs that require dotfiles in order to
7661 operate sensibly are a bad thing, unless they do create
7662 the dotfiles themselves automatically.
7666 Furthermore, programs should be configured by the Debian
7667 default installation to behave as closely to the upstream
7668 default behavior as possible.
7672 Therefore, if a program in a Debian package needs to be
7673 configured in some way in order to operate sensibly, that
7674 should be done using a site-wide configuration file placed
7675 in <file>/etc</file>. Only if the program doesn't support a
7676 site-wide default configuration and the package maintainer
7677 doesn't have time to add it may a default per-user file be
7678 placed in <file>/etc/skel</file>.
7682 <file>/etc/skel</file> should be as empty as we can make it.
7683 This is particularly true because there is no easy (or
7684 necessarily desirable) mechanism for ensuring that the
7685 appropriate dotfiles are copied into the accounts of
7686 existing users when a package is installed.
7692 <heading>Log files</heading>
7694 Log files should usually be named
7695 <file>/var/log/<var>package</var>.log</file>. If you have many
7696 log files, or need a separate directory for permission
7697 reasons (<file>/var/log</file> is writable only by
7698 <file>root</file>), you should usually create a directory named
7699 <file>/var/log/<var>package</var></file> and place your log
7704 Log files must be rotated occasionally so that they don't
7705 grow indefinitely; the best way to do this is to drop a log
7706 rotation configuration file into the directory
7707 <file>/etc/logrotate.d</file> and use the facilities provided by
7708 logrotate.<footnote>
7710 The traditional approach to log files has been to set up
7711 <em>ad hoc</em> log rotation schemes using simple shell
7712 scripts and cron. While this approach is highly
7713 customizable, it requires quite a lot of sysadmin work.
7714 Even though the original Debian system helped a little
7715 by automatically installing a system which can be used
7716 as a template, this was deemed not enough.
7720 The use of <prgn>logrotate</prgn>, a program developed
7721 by Red Hat, is better, as it centralizes log management.
7722 It has both a configuration file
7723 (<file>/etc/logrotate.conf</file>) and a directory where
7724 packages can drop their individual log rotation
7725 configurations (<file>/etc/logrotate.d</file>).
7728 Here is a good example for a logrotate config
7729 file (for more information see <manref name="logrotate"
7731 <example compact="compact">
7732 /var/log/foo/*.log {
7737 /etc/init.d/foo force-reload
7741 This rotates all files under <file>/var/log/foo</file>, saves 12
7742 compressed generations, and forces the daemon to reload its
7743 configuration information after the log rotation.
7747 Log files should be removed when the package is
7748 purged (but not when it is only removed). This should be
7749 done by the <prgn>postrm</prgn> script when it is called
7750 with the argument <tt>purge</tt> (see <ref
7751 id="removedetails">).
7756 <heading>Permissions and owners</heading>
7759 The rules in this section are guidelines for general use.
7760 If necessary you may deviate from the details below.
7761 However, if you do so you must make sure that what is done
7762 is secure and you should try to be as consistent as possible
7763 with the rest of the system. You should probably also
7764 discuss it on <prgn>debian-devel</prgn> first.
7768 Files should be owned by <tt>root:root</tt>, and made
7769 writable only by the owner and universally readable (and
7770 executable, if appropriate), that is mode 644 or 755.
7774 Directories should be mode 755 or (for group-writability)
7775 mode 2775. The ownership of the directory should be
7776 consistent with its mode: if a directory is mode 2775, it
7777 should be owned by the group that needs write access to
7780 When a package is upgraded, and the owner or permissions
7781 of a file included in the package has changed, dpkg
7782 arranges for the ownership and permissions to be
7783 correctly set upon installation. However, this does not
7784 extend to directories; the permissions and ownership of
7785 directories already on the system does not change on
7786 install or upgrade of packages. This makes sense, since
7787 otherwise common directories like <tt>/usr</tt> would
7788 always be in flux. To correctly change permissions of a
7789 directory the package owns, explicit action is required,
7790 usually in the <tt>postinst</tt> script. Care must be
7791 taken to handle downgrades as well, in that case.
7798 Setuid and setgid executables should be mode 4755 or 2755
7799 respectively, and owned by the appropriate user or group.
7800 They should not be made unreadable (modes like 4711 or
7801 2711 or even 4111); doing so achieves no extra security,
7802 because anyone can find the binary in the freely available
7803 Debian package; it is merely inconvenient. For the same
7804 reason you should not restrict read or execute permissions
7805 on non-set-id executables.
7809 Some setuid programs need to be restricted to particular
7810 sets of users, using file permissions. In this case they
7811 should be owned by the uid to which they are set-id, and by
7812 the group which should be allowed to execute them. They
7813 should have mode 4754; again there is no point in making
7814 them unreadable to those users who must not be allowed to
7819 It is possible to arrange that the system administrator can
7820 reconfigure the package to correspond to their local
7821 security policy by changing the permissions on a binary:
7822 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7823 described below.<footnote>
7824 Ordinary files installed by <prgn>dpkg</prgn> (as
7825 opposed to <tt>conffile</tt>s and other similar objects)
7826 normally have their permissions reset to the distributed
7827 permissions when the package is reinstalled. However,
7828 the use of <prgn>dpkg-statoverride</prgn> overrides this
7831 Another method you should consider is to create a group for
7832 people allowed to use the program(s) and make any setuid
7833 executables executable only by that group.
7837 If you need to create a new user or group for your package
7838 there are two possibilities. Firstly, you may need to
7839 make some files in the binary package be owned by this
7840 user or group, or you may need to compile the user or
7841 group id (rather than just the name) into the binary
7842 (though this latter should be avoided if possible, as in
7843 this case you need a statically allocated id).</p>
7846 If you need a statically allocated id, you must ask for a
7847 user or group id from the <tt>base-passwd</tt> maintainer,
7848 and must not release the package until you have been
7849 allocated one. Once you have been allocated one you must
7850 either make the package depend on a version of the
7851 <tt>base-passwd</tt> package with the id present in
7852 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7853 your package to create the user or group itself with the
7854 correct id (using <tt>adduser</tt>) in its
7855 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7856 the <prgn>postinst</prgn> is to be preferred if it is
7857 possible, otherwise a pre-dependency will be needed on the
7858 <tt>adduser</tt> package.)
7862 On the other hand, the program might be able to determine
7863 the uid or gid from the user or group name at runtime, so
7864 that a dynamically allocated id can be used. In this case
7865 you should choose an appropriate user or group name,
7866 discussing this on <prgn>debian-devel</prgn> and checking
7867 with the <package/base-passwd/ maintainer that it is unique and that
7868 they do not wish you to use a statically allocated id
7869 instead. When this has been checked you must arrange for
7870 your package to create the user or group if necessary using
7871 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7872 <prgn>postinst</prgn> script (again, the latter is to be
7873 preferred if it is possible).
7877 Note that changing the numeric value of an id associated
7878 with a name is very difficult, and involves searching the
7879 file system for all appropriate files. You need to think
7880 carefully whether a static or dynamic id is required, since
7881 changing your mind later will cause problems.
7884 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7886 This section is not intended as policy, but as a
7887 description of the use of <prgn>dpkg-statoverride</prgn>.
7891 If a system administrator wishes to have a file (or
7892 directory or other such thing) installed with owner and
7893 permissions different from those in the distributed Debian
7894 package, they can use the <prgn>dpkg-statoverride</prgn>
7895 program to instruct <prgn>dpkg</prgn> to use the different
7896 settings every time the file is installed. Thus the
7897 package maintainer should distribute the files with their
7898 normal permissions, and leave it for the system
7899 administrator to make any desired changes. For example, a
7900 daemon which is normally required to be setuid root, but
7901 in certain situations could be used without being setuid,
7902 should be installed setuid in the <tt>.deb</tt>. Then the
7903 local system administrator can change this if they wish.
7904 If there are two standard ways of doing it, the package
7905 maintainer can use <tt>debconf</tt> to find out the
7906 preference, and call <prgn>dpkg-statoverride</prgn> in the
7907 maintainer script if necessary to accommodate the system
7908 administrator's choice. Care must be taken during
7909 upgrades to not override an existing setting.
7913 Given the above, <prgn>dpkg-statoverride</prgn> is
7914 essentially a tool for system administrators and would not
7915 normally be needed in the maintainer scripts. There is
7916 one type of situation, though, where calls to
7917 <prgn>dpkg-statoverride</prgn> would be needed in the
7918 maintainer scripts, and that involves packages which use
7919 dynamically allocated user or group ids. In such a
7920 situation, something like the following idiom can be very
7921 helpful in the package's <prgn>postinst</prgn>, where
7922 <tt>sysuser</tt> is a dynamically allocated id:
7924 for i in /usr/bin/foo /usr/sbin/bar
7926 # only do something when no setting exists
7927 if ! dpkg-statoverride --list $i >/dev/null 2>&1
7929 #include: debconf processing, question about foo and bar
7930 if [ "$RET" = "true" ] ; then
7931 dpkg-statoverride --update --add sysuser root 4755 $i
7936 The corresponding code to remove the override when the package
7939 for i in /usr/bin/foo /usr/sbin/bar
7941 if dpkg-statoverride --list $i >/dev/null 2>&1
7943 dpkg-statoverride --remove $i
7953 <chapt id="customized-programs">
7954 <heading>Customized programs</heading>
7956 <sect id="arch-spec">
7957 <heading>Architecture specification strings</heading>
7960 If a program needs to specify an <em>architecture specification
7961 string</em> in some place, it should select one of the
7962 strings provided by <tt>dpkg-architecture -L</tt>. The
7963 strings are in the format
7964 <tt><var>os</var>-<var>arch</var></tt>, though the OS part
7965 is sometimes elided, as when the OS is Linux.<footnote>
7966 <p>Currently, the strings are:
7967 i386 ia64 alpha amd64 armeb arm hppa m32r m68k mips
7968 mipsel powerpc ppc64 s390 s390x sh3 sh3eb sh4 sh4eb
7969 sparc darwin-i386 darwin-ia64 darwin-alpha darwin-amd64
7970 darwin-armeb darwin-arm darwin-hppa darwin-m32r
7971 darwin-m68k darwin-mips darwin-mipsel darwin-powerpc
7972 darwin-ppc64 darwin-s390 darwin-s390x darwin-sh3
7973 darwin-sh3eb darwin-sh4 darwin-sh4eb darwin-sparc
7974 freebsd-i386 freebsd-ia64 freebsd-alpha freebsd-amd64
7975 freebsd-armeb freebsd-arm freebsd-hppa freebsd-m32r
7976 freebsd-m68k freebsd-mips freebsd-mipsel freebsd-powerpc
7977 freebsd-ppc64 freebsd-s390 freebsd-s390x freebsd-sh3
7978 freebsd-sh3eb freebsd-sh4 freebsd-sh4eb freebsd-sparc
7979 kfreebsd-i386 kfreebsd-ia64 kfreebsd-alpha
7980 kfreebsd-amd64 kfreebsd-armeb kfreebsd-arm kfreebsd-hppa
7981 kfreebsd-m32r kfreebsd-m68k kfreebsd-mips
7982 kfreebsd-mipsel kfreebsd-powerpc kfreebsd-ppc64
7983 kfreebsd-s390 kfreebsd-s390x kfreebsd-sh3 kfreebsd-sh3eb
7984 kfreebsd-sh4 kfreebsd-sh4eb kfreebsd-sparc knetbsd-i386
7985 knetbsd-ia64 knetbsd-alpha knetbsd-amd64 knetbsd-armeb
7986 knetbsd-arm knetbsd-hppa knetbsd-m32r knetbsd-m68k
7987 knetbsd-mips knetbsd-mipsel knetbsd-powerpc
7988 knetbsd-ppc64 knetbsd-s390 knetbsd-s390x knetbsd-sh3
7989 knetbsd-sh3eb knetbsd-sh4 knetbsd-sh4eb knetbsd-sparc
7990 netbsd-i386 netbsd-ia64 netbsd-alpha netbsd-amd64
7991 netbsd-armeb netbsd-arm netbsd-hppa netbsd-m32r
7992 netbsd-m68k netbsd-mips netbsd-mipsel netbsd-powerpc
7993 netbsd-ppc64 netbsd-s390 netbsd-s390x netbsd-sh3
7994 netbsd-sh3eb netbsd-sh4 netbsd-sh4eb netbsd-sparc
7995 openbsd-i386 openbsd-ia64 openbsd-alpha openbsd-amd64
7996 openbsd-armeb openbsd-arm openbsd-hppa openbsd-m32r
7997 openbsd-m68k openbsd-mips openbsd-mipsel openbsd-powerpc
7998 openbsd-ppc64 openbsd-s390 openbsd-s390x openbsd-sh3
7999 openbsd-sh3eb openbsd-sh4 openbsd-sh4eb openbsd-sparc
8000 hurd-i386 hurd-ia64 hurd-alpha hurd-amd64 hurd-armeb
8001 hurd-arm hurd-hppa hurd-m32r hurd-m68k hurd-mips
8002 hurd-mipsel hurd-powerpc hurd-ppc64 hurd-s390 hurd-s390x
8003 hurd-sh3 hurd-sh3eb hurd-sh4 hurd-sh4eb hurd-sparc
8009 Note that we don't want to use
8010 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
8011 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
8012 since this would make our programs incompatible with other
8013 Linux distributions. We also don't use something like
8014 <tt><var>arch</var>-unknown-linux</tt>, since the
8015 <tt>unknown</tt> does not look very good.
8019 <sect id="arch-wildcard-spec">
8020 <heading>Architecture Wildcards</heading>
8023 A package may specify an architecture wildcard. Architecture
8024 wildcards are in the format <tt>any</tt> (which matches every
8025 architecture), <tt><var>os</var></tt>-any, or
8026 any-<tt><var>cpu</var></tt>. <footnote>
8027 Internally, the package system normalizes the GNU triplets and
8028 the Debian arches into Debian arch triplets (which are kind of
8029 inverted GNU triplets), with the first component of the
8030 triplet representing the libc and ABI in use, and then does
8031 matching against those triplets. However, such triplets are
8032 an internal implementation detail that should not be used by
8033 packages directly. The libc and ABI portion is handled
8034 internally by the package system based on the <var>os</var>
8041 <heading>Daemons</heading>
8044 The configuration files <file>/etc/services</file>,
8045 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
8046 by the <prgn>netbase</prgn> package and must not be modified
8051 If a package requires a new entry in one of these files, the
8052 maintainer should get in contact with the
8053 <prgn>netbase</prgn> maintainer, who will add the entries
8054 and release a new version of the <prgn>netbase</prgn>
8059 The configuration file <file>/etc/inetd.conf</file> must not be
8060 modified by the package's scripts except via the
8061 <prgn>update-inetd</prgn> script or the
8062 <file>DebianNet.pm</file> Perl module. See their documentation
8063 for details on how to add entries.
8067 If a package wants to install an example entry into
8068 <file>/etc/inetd.conf</file>, the entry must be preceded with
8069 exactly one hash character (<tt>#</tt>). Such lines are
8070 treated as "commented out by user" by the
8071 <prgn>update-inetd</prgn> script and are not changed or
8072 activated during package updates.
8077 <heading>Using pseudo-ttys and modifying wtmp, utmp and
8081 Some programs need to create pseudo-ttys. This should be done
8082 using Unix98 ptys if the C library supports it. The resulting
8083 program must not be installed setuid root, unless that
8084 is required for other functionality.
8088 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
8089 <file>/var/log/lastlog</file> must be installed writable by
8090 group <tt>utmp</tt>. Programs which need to modify those
8091 files must be installed setgid <tt>utmp</tt>.
8096 <heading>Editors and pagers</heading>
8099 Some programs have the ability to launch an editor or pager
8100 program to edit or display a text document. Since there are
8101 lots of different editors and pagers available in the Debian
8102 distribution, the system administrator and each user should
8103 have the possibility to choose their preferred editor and
8108 In addition, every program should choose a good default
8109 editor/pager if none is selected by the user or system
8114 Thus, every program that launches an editor or pager must
8115 use the EDITOR or PAGER environment variable to determine
8116 the editor or pager the user wishes to use. If these
8117 variables are not set, the programs <file>/usr/bin/editor</file>
8118 and <file>/usr/bin/pager</file> should be used, respectively.
8122 These two files are managed through the <prgn>dpkg</prgn>
8123 "alternatives" mechanism. Thus every package providing an
8124 editor or pager must call the
8125 <prgn>update-alternatives</prgn> script to register these
8130 If it is very hard to adapt a program to make use of the
8131 EDITOR or PAGER variables, that program may be configured to
8132 use <file>/usr/bin/sensible-editor</file> and
8133 <file>/usr/bin/sensible-pager</file> as the editor or pager
8134 program respectively. These are two scripts provided in the
8135 <package>sensible-utils</package> package that check the EDITOR
8136 and PAGER variables and launch the appropriate program, and fall
8137 back to <file>/usr/bin/editor</file>
8138 and <file>/usr/bin/pager</file> if the variable is not set.
8142 A program may also use the VISUAL environment variable to
8143 determine the user's choice of editor. If it exists, it
8144 should take precedence over EDITOR. This is in fact what
8145 <file>/usr/bin/sensible-editor</file> does.
8149 It is not required for a package to depend on
8150 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
8151 package to provide such virtual packages.<footnote>
8152 The Debian base system already provides an editor and a
8158 <sect id="web-appl">
8159 <heading>Web servers and applications</heading>
8162 This section describes the locations and URLs that should
8163 be used by all web servers and web applications in the
8170 Cgi-bin executable files are installed in the
8172 <example compact="compact">
8173 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
8175 and should be referred to as
8176 <example compact="compact">
8177 http://localhost/cgi-bin/<var>cgi-bin-name</var>
8183 <p>Access to HTML documents</p>
8186 HTML documents for a package are stored in
8187 <file>/usr/share/doc/<var>package</var></file>
8188 and can be referred to as
8189 <example compact="compact">
8190 http://localhost/doc/<var>package</var>/<var>filename</var>
8195 The web server should restrict access to the document
8196 tree so that only clients on the same host can read
8197 the documents. If the web server does not support such
8198 access controls, then it should not provide access at
8199 all, or ask about providing access during installation.
8204 <p>Access to images</p>
8206 It is recommended that images for a package be stored
8207 in <tt>/usr/share/images/<var>package</var></tt> and
8208 may be referred to through an alias <tt>/images/</tt>
8211 http://localhost/images/<package>/<filename>
8218 <p>Web Document Root</p>
8221 Web Applications should try to avoid storing files in
8222 the Web Document Root. Instead they should use the
8223 /usr/share/doc/<var>package</var> directory for
8224 documents and register the Web Application via the
8225 <package>doc-base</package> package. If access to the
8226 web document root is unavoidable then use
8227 <example compact="compact">
8230 as the Document Root. This might be just a symbolic
8231 link to the location where the system administrator
8232 has put the real document root.
8235 <item><p>Providing httpd and/or httpd-cgi</p>
8237 All web servers should provide the virtual package
8238 <tt>httpd</tt>. If a web server has CGI support it should
8239 provide <tt>httpd-cgi</tt> additionally.
8242 All web applications which do not contain CGI scripts should
8243 depend on <tt>httpd</tt>, all those web applications which
8244 <tt>do</tt> contain CGI scripts, should depend on
8252 <sect id="mail-transport-agents">
8253 <heading>Mail transport, delivery and user agents</heading>
8256 Debian packages which process electronic mail, whether mail
8257 user agents (MUAs) or mail transport agents (MTAs), must
8258 ensure that they are compatible with the configuration
8259 decisions below. Failure to do this may result in lost
8260 mail, broken <tt>From:</tt> lines, and other serious brain
8265 The mail spool is <file>/var/mail</file> and the interface to
8266 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8267 the FHS). On older systems, the mail spool may be
8268 physically located in <file>/var/spool/mail</file>, but all
8269 access to the mail spool should be via the
8270 <file>/var/mail</file> symlink. The mail spool is part of the
8271 base system and not part of the MTA package.
8275 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8276 programs (such as IMAP daemons) must lock the mailbox in an
8277 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8278 be combined with dot locking. To avoid deadlocks, a program
8279 should use <tt>fcntl()</tt> first and dot locking after
8280 this, or alternatively implement the two locking methods in
8281 a non blocking way<footnote>
8282 If it is not possible to establish both locks, the
8283 system shouldn't wait for the second lock to be
8284 established, but remove the first lock, wait a (random)
8285 time, and start over locking again.
8286 </footnote>. Using the functions <tt>maillock</tt> and
8287 <tt>mailunlock</tt> provided by the
8288 <tt>liblockfile*</tt><footnote>
8289 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8290 to use these functions.
8291 </footnote> packages is the recommended way to realize this.
8295 Mailboxes are generally either mode 600 and owned by
8296 <var>user</var> or mode 660 and owned by
8297 <tt><var>user</var>:mail</tt><footnote>
8298 There are two traditional permission schemes for mail spools:
8299 mode 600 with all mail delivery done by processes running as
8300 the destination user, or mode 660 and owned by group mail with
8301 mail delivery done by a process running as a system user in
8302 group mail. Historically, Debian required mode 660 mail
8303 spools to enable the latter model, but that model has become
8304 increasingly uncommon and the principle of least privilege
8305 indicates that mail systems that use the first model should
8306 use permissions of 600. If delivery to programs is permitted,
8307 it's easier to keep the mail system secure if the delivery
8308 agent runs as the destination user. Debian Policy therefore
8309 permits either scheme.
8310 </footnote>. The local system administrator may choose a
8311 different permission scheme; packages should not make
8312 assumptions about the permission and ownership of mailboxes
8313 unless required (such as when creating a new mailbox). A MUA
8314 may remove a mailbox (unless it has nonstandard permissions) in
8315 which case the MTA or another MUA must recreate it if needed.
8319 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8320 be setgid mail to do the locking mentioned above (and
8321 must obviously avoid accessing other users' mailboxes
8322 using this privilege).</p>
8325 <file>/etc/aliases</file> is the source file for the system mail
8326 aliases (e.g., postmaster, usenet, etc.), it is the one
8327 which the sysadmin and <prgn>postinst</prgn> scripts may
8328 edit. After <file>/etc/aliases</file> is edited the program or
8329 human editing it must call <prgn>newaliases</prgn>. All MTA
8330 packages must come with a <prgn>newaliases</prgn> program,
8331 even if it does nothing, but older MTA packages did not do
8332 this so programs should not fail if <prgn>newaliases</prgn>
8333 cannot be found. Note that because of this, all MTA
8334 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8335 <tt>Replaces: mail-transport-agent</tt> control file
8340 The convention of writing <tt>forward to
8341 <var>address</var></tt> in the mailbox itself is not
8342 supported. Use a <tt>.forward</tt> file instead.</p>
8345 The <prgn>rmail</prgn> program used by UUCP
8346 for incoming mail should be <file>/usr/sbin/rmail</file>.
8347 Likewise, <prgn>rsmtp</prgn>, for receiving
8348 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8352 If your package needs to know what hostname to use on (for
8353 example) outgoing news and mail messages which are generated
8354 locally, you should use the file <file>/etc/mailname</file>. It
8355 will contain the portion after the username and <tt>@</tt>
8356 (at) sign for email addresses of users on the machine
8357 (followed by a newline).
8361 Such a package should check for the existence of this file
8362 when it is being configured. If it exists, it should be
8363 used without comment, although an MTA's configuration script
8364 may wish to prompt the user even if it finds that this file
8365 exists. If the file does not exist, the package should
8366 prompt the user for the value (preferably using
8367 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8368 as well as using it in the package's configuration. The
8369 prompt should make it clear that the name will not just be
8370 used by that package. For example, in this situation the
8371 <tt>inn</tt> package could say something like:
8372 <example compact="compact">
8373 Please enter the "mail name" of your system. This is the
8374 hostname portion of the address to be shown on outgoing
8375 news and mail messages. The default is
8376 <var>syshostname</var>, your system's host name. Mail
8377 name ["<var>syshostname</var>"]:
8379 where <var>syshostname</var> is the output of <tt>hostname
8385 <heading>News system configuration</heading>
8388 All the configuration files related to the NNTP (news)
8389 servers and clients should be located under
8390 <file>/etc/news</file>.</p>
8393 There are some configuration issues that apply to a number
8394 of news clients and server packages on the machine. These
8398 <tag><file>/etc/news/organization</file></tag>
8400 A string which should appear as the
8401 organization header for all messages posted
8402 by NNTP clients on the machine
8405 <tag><file>/etc/news/server</file></tag>
8407 Contains the FQDN of the upstream NNTP
8408 server, or localhost if the local machine is
8413 Other global files may be added as required for cross-package news
8420 <heading>Programs for the X Window System</heading>
8423 <heading>Providing X support and package priorities</heading>
8426 Programs that can be configured with support for the X
8427 Window System must be configured to do so and must declare
8428 any package dependencies necessary to satisfy their
8429 runtime requirements when using the X Window System. If
8430 such a package is of higher priority than the X packages
8431 on which it depends, it is required that either the
8432 X-specific components be split into a separate package, or
8433 that an alternative version of the package, which includes
8434 X support, be provided, or that the package's priority be
8440 <heading>Packages providing an X server</heading>
8443 Packages that provide an X server that, directly or
8444 indirectly, communicates with real input and display
8445 hardware should declare in their control data that they
8446 provide the virtual package <tt>xserver</tt>.<footnote>
8447 This implements current practice, and provides an
8448 actual policy for usage of the <tt>xserver</tt>
8449 virtual package which appears in the virtual packages
8450 list. In a nutshell, X servers that interface
8451 directly with the display and input hardware or via
8452 another subsystem (e.g., GGI) should provide
8453 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8454 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8460 <heading>Packages providing a terminal emulator</heading>
8463 Packages that provide a terminal emulator for the X Window
8464 System which meet the criteria listed below should declare
8465 in their control data that they provide the virtual
8466 package <tt>x-terminal-emulator</tt>. They should also
8467 register themselves as an alternative for
8468 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8473 To be an <tt>x-terminal-emulator</tt>, a program must:
8474 <list compact="compact">
8476 Be able to emulate a DEC VT100 terminal, or a
8477 compatible terminal.
8481 Support the command-line option <tt>-e
8482 <var>command</var></tt>, which creates a new
8483 terminal window<footnote>
8484 "New terminal window" does not necessarily mean
8485 a new top-level X window directly parented by
8486 the window manager; it could, if the terminal
8487 emulator application were so coded, be a new
8488 "view" in a multiple-document interface (MDI).
8490 and runs the specified <var>command</var>,
8491 interpreting the entirety of the rest of the command
8492 line as a command to pass straight to exec, in the
8493 manner that <tt>xterm</tt> does.
8497 Support the command-line option <tt>-T
8498 <var>title</var></tt>, which creates a new terminal
8499 window with the window title <var>title</var>.
8506 <heading>Packages providing a window manager</heading>
8509 Packages that provide a window manager should declare in
8510 their control data that they provide the virtual package
8511 <tt>x-window-manager</tt>. They should also register
8512 themselves as an alternative for
8513 <file>/usr/bin/x-window-manager</file>, with a priority
8514 calculated as follows:
8515 <list compact="compact">
8517 Start with a priority of 20.
8521 If the window manager supports the Debian menu
8522 system, add 20 points if this support is available
8523 in the package's default configuration (i.e., no
8524 configuration files belonging to the system or user
8525 have to be edited to activate the feature); if
8526 configuration files must be modified, add only 10
8532 If the window manager complies with <url
8533 id="http://www.freedesktop.org/Standards/wm-spec"
8534 name="The Window Manager Specification Project">,
8535 written by the <url id="http://www.freedesktop.org/"
8536 name="Free Desktop Group">, add 40 points.
8540 If the window manager permits the X session to be
8541 restarted using a <em>different</em> window manager
8542 (without killing the X server) in its default
8543 configuration, add 10 points; otherwise add none.
8550 <heading>Packages providing fonts</heading>
8553 Packages that provide fonts for the X Window
8555 For the purposes of Debian Policy, a "font for the X
8556 Window System" is one which is accessed via X protocol
8557 requests. Fonts for the Linux console, for PostScript
8558 renderer, or any other purpose, do not fit this
8559 definition. Any tool which makes such fonts available
8560 to the X Window System, however, must abide by this
8563 must do a number of things to ensure that they are both
8564 available without modification of the X or font server
8565 configuration, and that they do not corrupt files used by
8566 other font packages to register information about
8570 Fonts of any type supported by the X Window System
8571 must be in a separate binary package from any
8572 executables, libraries, or documentation (except
8573 that specific to the fonts shipped, such as their
8574 license information). If one or more of the fonts
8575 so packaged are necessary for proper operation of
8576 the package with which they are associated the font
8577 package may be Recommended; if the fonts merely
8578 provide an enhancement, a Suggests relationship may
8579 be used. Packages must not Depend on font
8581 This is because the X server may retrieve fonts
8582 from the local file system or over the network
8583 from an X font server; the Debian package system
8584 is empowered to deal only with the local
8590 BDF fonts must be converted to PCF fonts with the
8591 <prgn>bdftopcf</prgn> utility (available in the
8592 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8593 placed in a directory that corresponds to their
8595 <list compact="compact">
8597 100 dpi fonts must be placed in
8598 <file>/usr/share/fonts/X11/100dpi/</file>.
8602 75 dpi fonts must be placed in
8603 <file>/usr/share/fonts/X11/75dpi/</file>.
8607 Character-cell fonts, cursor fonts, and other
8608 low-resolution fonts must be placed in
8609 <file>/usr/share/fonts/X11/misc/</file>.
8615 Type 1 fonts must be placed in
8616 <file>/usr/share/fonts/X11/Type1/</file>. If font
8617 metric files are available, they must be placed here
8622 Subdirectories of <file>/usr/share/fonts/X11/</file>
8623 other than those listed above must be neither
8624 created nor used. (The <file>PEX</file>, <file>CID</file>,
8625 <file>Speedo</file>, and <file>cyrillic</file> directories
8626 are excepted for historical reasons, but installation of
8627 files into these directories remains discouraged.)
8631 Font packages may, instead of placing files directly
8632 in the X font directories listed above, provide
8633 symbolic links in that font directory pointing to
8634 the files' actual location in the filesystem. Such
8635 a location must comply with the FHS.
8639 Font packages should not contain both 75dpi and
8640 100dpi versions of a font. If both are available,
8641 they should be provided in separate binary packages
8642 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8643 the names of the packages containing the
8644 corresponding fonts.
8648 Fonts destined for the <file>misc</file> subdirectory
8649 should not be included in the same package as 75dpi
8650 or 100dpi fonts; instead, they should be provided in
8651 a separate package with <tt>-misc</tt> appended to
8656 Font packages must not provide the files
8657 <file>fonts.dir</file>, <file>fonts.alias</file>, or
8658 <file>fonts.scale</file> in a font directory:
8661 <file>fonts.dir</file> files must not be provided at all.
8665 <file>fonts.alias</file> and <file>fonts.scale</file>
8666 files, if needed, should be provided in the
8668 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
8669 where <var>fontdir</var> is the name of the
8671 <file>/usr/share/fonts/X11/</file> where the
8672 package's corresponding fonts are stored
8673 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
8674 <var>package</var> is the name of the package
8675 that provides these fonts, and
8676 <var>extension</var> is either <tt>scale</tt>
8677 or <tt>alias</tt>, whichever corresponds to
8684 Font packages must declare a dependency on
8685 <tt>xfonts-utils</tt> in their control
8690 Font packages that provide one or more
8691 <file>fonts.scale</file> files as described above must
8692 invoke <prgn>update-fonts-scale</prgn> on each
8693 directory into which they installed fonts
8694 <em>before</em> invoking
8695 <prgn>update-fonts-dir</prgn> on that directory.
8696 This invocation must occur in both the
8697 <prgn>postinst</prgn> (for all arguments) and
8698 <prgn>postrm</prgn> (for all arguments except
8699 <tt>upgrade</tt>) scripts.
8703 Font packages that provide one or more
8704 <file>fonts.alias</file> files as described above must
8705 invoke <prgn>update-fonts-alias</prgn> on each
8706 directory into which they installed fonts. This
8707 invocation must occur in both the
8708 <prgn>postinst</prgn> (for all arguments) and
8709 <prgn>postrm</prgn> (for all arguments except
8710 <tt>upgrade</tt>) scripts.
8714 Font packages must invoke
8715 <prgn>update-fonts-dir</prgn> on each directory into
8716 which they installed fonts. This invocation must
8717 occur in both the <prgn>postinst</prgn> (for all
8718 arguments) and <prgn>postrm</prgn> (for all
8719 arguments except <tt>upgrade</tt>) scripts.
8723 Font packages must not provide alias names for the
8724 fonts they include which collide with alias names
8725 already in use by fonts already packaged.
8729 Font packages must not provide fonts with the same
8730 XLFD registry name as another font already packaged.
8736 <sect1 id="appdefaults">
8737 <heading>Application defaults files</heading>
8740 Application defaults files must be installed in the
8741 directory <file>/etc/X11/app-defaults/</file> (use of a
8742 localized subdirectory of <file>/etc/X11/</file> as described
8743 in the <em>X Toolkit Intrinsics - C Language
8744 Interface</em> manual is also permitted). They must be
8745 registered as <tt>conffile</tt>s or handled as
8746 configuration files.
8750 Customization of programs' X resources may also be
8751 supported with the provision of a file with the same name
8752 as that of the package placed in
8753 the <file>/etc/X11/Xresources/</file> directory, which
8754 must be registered as a <tt>conffile</tt> or handled as a
8755 configuration file.<footnote>
8756 Note that this mechanism is not the same as using
8757 app-defaults; app-defaults are tied to the client
8758 binary on the local file system, whereas X resources
8759 are stored in the X server and affect all connecting
8766 <heading>Installation directory issues</heading>
8769 Historically, packages using the X Window System used a
8770 separate set of installation directories from other packages.
8771 This practice has been discontinued and packages using the X
8772 Window System should now generally be installed in the same
8773 directories as any other package. Specifically, packages must
8774 not install files under the <file>/usr/X11R6/</file> directory
8775 and the <file>/usr/X11R6/</file> directory hierarchy should be
8776 regarded as obsolete.
8780 Include files previously installed under
8781 <file>/usr/X11R6/include/X11/</file> should be installed into
8782 <file>/usr/include/X11/</file>. For files previously
8783 installed into subdirectories of
8784 <file>/usr/X11R6/lib/X11/</file>, package maintainers should
8785 determine if subdirectories of <file>/usr/lib/</file> and
8786 <file>/usr/share/</file> can be used. If not, a subdirectory
8787 of <file>/usr/lib/X11/</file> should be used.
8791 Configuration files for window, display, or session managers
8792 or other applications that are tightly integrated with the X
8793 Window System may be placed in a subdirectory
8794 of <file>/etc/X11/</file> corresponding to the package name.
8795 Other X Window System applications should use
8796 the <file>/etc/</file> directory unless otherwise mandated by
8797 policy (such as for <ref id="appdefaults">).
8802 <heading>The OSF/Motif and OpenMotif libraries</heading>
8805 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8806 OpenMotif libraries</em><footnote>
8807 OSF/Motif and OpenMotif are collectively referred to as
8808 "Motif" in this policy document.
8810 should be compiled against and tested with LessTif (a free
8811 re-implementation of Motif) instead. If the maintainer
8812 judges that the program or programs do not work
8813 sufficiently well with LessTif to be distributed and
8814 supported, but do so when compiled against Motif, then two
8815 versions of the package should be created; one linked
8816 statically against Motif and with <tt>-smotif</tt>
8817 appended to the package name, and one linked dynamically
8818 against Motif and with <tt>-dmotif</tt> appended to the
8823 Both Motif-linked versions are dependent
8824 upon non-DFSG-compliant software and thus cannot be
8825 uploaded to the <em>main</em> distribution; if the
8826 software is itself DFSG-compliant it may be uploaded to
8827 the <em>contrib</em> distribution. While known existing
8828 versions of Motif permit unlimited redistribution of
8829 binaries linked against the library (whether statically or
8830 dynamically), it is the package maintainer's
8831 responsibility to determine whether this is permitted by
8832 the license of the copy of Motif in their possession.
8838 <heading>Perl programs and modules</heading>
8841 Perl programs and modules should follow the current Perl policy.
8845 The Perl policy can be found in the <tt>perl-policy</tt>
8846 files in the <tt>debian-policy</tt> package.
8847 It is also available from the Debian web mirrors at
8848 <tt><url name="/doc/packaging-manuals/perl-policy/"
8849 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8854 <heading>Emacs lisp programs</heading>
8857 Please refer to the "Debian Emacs Policy" for details of how to
8858 package emacs lisp programs.
8862 The Emacs policy is available in
8863 <file>debian-emacs-policy.gz</file> of the
8864 <package>emacsen-common</package> package.
8865 It is also available from the Debian web mirrors at
8866 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8867 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8872 <heading>Games</heading>
8875 The permissions on <file>/var/games</file> are mode 755, owner
8876 <tt>root</tt> and group <tt>root</tt>.
8880 Each game decides on its own security policy.</p>
8883 Games which require protected, privileged access to
8884 high-score files, saved games, etc., may be made
8885 set-<em>group</em>-id (mode 2755) and owned by
8886 <tt>root:games</tt>, and use files and directories with
8887 appropriate permissions (770 <tt>root:games</tt>, for
8888 example). They must not be made
8889 set-<em>user</em>-id, as this causes security problems. (If
8890 an attacker can subvert any set-user-id game they can
8891 overwrite the executable of any other, causing other players
8892 of these games to run a Trojan horse program. With a
8893 set-group-id game the attacker only gets access to less
8894 important game data, and if they can get at the other
8895 players' accounts at all it will take considerably more
8899 Some packages, for example some fortune cookie programs, are
8900 configured by the upstream authors to install with their
8901 data files or other static information made unreadable so
8902 that they can only be accessed through set-id programs
8903 provided. You should not do this in a Debian package: anyone can
8904 download the <file>.deb</file> file and read the data from it,
8905 so there is no point making the files unreadable. Not
8906 making the files unreadable also means that you don't have
8907 to make so many programs set-id, which reduces the risk of a
8911 As described in the FHS, binaries of games should be
8912 installed in the directory <file>/usr/games</file>. This also
8913 applies to games that use the X Window System. Manual pages
8914 for games (X and non-X games) should be installed in
8915 <file>/usr/share/man/man6</file>.</p>
8921 <heading>Documentation</heading>
8924 <heading>Manual pages</heading>
8927 You should install manual pages in <prgn>nroff</prgn> source
8928 form, in appropriate places under <file>/usr/share/man</file>.
8929 You should only use sections 1 to 9 (see the FHS for more
8930 details). You must not install a pre-formatted "cat page".
8934 Each program, utility, and function should have an
8935 associated manual page included in the same package. It is
8936 suggested that all configuration files also have a manual
8937 page included as well. Manual pages for protocols and other
8938 auxiliary things are optional.
8942 If no manual page is available, this is considered as a bug
8943 and should be reported to the Debian Bug Tracking System (the
8944 maintainer of the package is allowed to write this bug report
8945 themselves, if they so desire). Do not close the bug report
8946 until a proper man page is available.<footnote>
8947 It is not very hard to write a man page. See the
8948 <url id="http://www.schweikhardt.net/man_page_howto.html"
8949 name="Man-Page-HOWTO">,
8950 <manref name="man" section="7">, the examples
8951 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8952 the helper programs <prgn>help2man</prgn>, or the
8953 directory <file>/usr/share/doc/man-db/examples</file>.
8958 You may forward a complaint about a missing man page to the
8959 upstream authors, and mark the bug as forwarded in the
8960 Debian bug tracking system. Even though the GNU Project do
8961 not in general consider the lack of a man page to be a bug,
8962 we do; if they tell you that they don't consider it a bug
8963 you should leave the bug in our bug tracking system open
8968 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8972 If one man page needs to be accessible via several names it
8973 is better to use a symbolic link than the <file>.so</file>
8974 feature, but there is no need to fiddle with the relevant
8975 parts of the upstream source to change from <file>.so</file> to
8976 symlinks: don't do it unless it's easy. You should not
8977 create hard links in the manual page directories, nor put
8978 absolute filenames in <file>.so</file> directives. The filename
8979 in a <file>.so</file> in a man page should be relative to the
8980 base of the man page tree (usually
8981 <file>/usr/share/man</file>). If you do not create any links
8982 (whether symlinks, hard links, or <tt>.so</tt> directives)
8983 in the file system to the alternate names of the man page,
8984 then you should not rely on <prgn>man</prgn> finding your
8985 man page under those names based solely on the information in
8986 the man page's header.<footnote>
8987 Supporting this in <prgn>man</prgn> often requires
8988 unreasonable processing time to find a manual page or to
8989 report that none exists, and moves knowledge into man's
8990 database that would be better left in the file system.
8991 This support is therefore deprecated and will cease to
8992 be present in the future.
8997 Manual pages in locale-specific subdirectories of
8998 <file>/usr/share/man</file> should use either UTF-8 or the usual
8999 legacy encoding for that language (normally the one corresponding
9000 to the shortest relevant locale name in
9001 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
9002 <file>/usr/share/man/fr</file> should use either UTF-8 or
9003 ISO-8859-1.<footnote>
9004 <prgn>man</prgn> will automatically detect whether UTF-8 is in
9005 use. In future, all manual pages will be required to use
9011 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
9012 included in the subdirectory name unless it indicates a
9013 significant difference in the language, as this excludes
9014 speakers of the language in other countries.<footnote>
9015 At the time of writing, Chinese and Portuguese are the main
9016 languages with such differences, so <file>pt_BR</file>,
9017 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
9022 If a localized version of a manual page is provided, it should
9023 either be up-to-date or it should be obvious to the reader that
9024 it is outdated and the original manual page should be used
9025 instead. This can be done either by a note at the beginning of
9026 the manual page or by showing the missing or changed portions in
9027 the original language instead of the target language.
9032 <heading>Info documents</heading>
9035 Info documents should be installed in <file>/usr/share/info</file>.
9036 They should be compressed with <tt>gzip -9</tt>.
9040 The <prgn>install-info</prgn> program maintains a directory of
9041 installed info documents in <file>/usr/share/info/dir</file> for
9042 the use of info readers.<footnote>
9043 It was previously necessary for packages installing info
9044 documents to run <prgn>install-info</prgn> from maintainer
9045 scripts. This is no longer necessary. The installation
9046 system now uses dpkg triggers.
9048 This file must not be included in packages. Packages containing
9049 info documents should depend on <tt>dpkg (>= 1.15.4) |
9050 install-info</tt> to ensure that the directory file is properly
9051 rebuilt during partial upgrades from Debian 5.0 (lenny) and
9056 Info documents should contain section and directory entry
9057 information in the document for the use
9058 of <prgn>install-info</prgn>. The section should be specified
9059 via a line starting with <tt>INFO-DIR-SECTION</tt> followed by a
9060 space and the section of this info page. The directory entry or
9061 entries should be included between
9062 a <tt>START-INFO-DIR-ENTRY</tt> line and
9063 an <tt>END-INFO-DIR-ENTRY</tt> line. For example:
9065 INFO-DIR-SECTION Individual utilities
9066 START-INFO-DIR-ENTRY
9067 * example: (example). An example info directory entry.
9070 To determine which section to use, you should look
9071 at <file>/usr/share/info/dir</file> on your system and choose
9072 the most relevant (or create a new section if none of the
9073 current sections are relevant).<footnote>
9074 Normally, info documents are generated from Texinfo source.
9075 To include this information in the generated info document, if
9076 it is absent, add commands like:
9078 @dircategory Individual utilities
9080 * example: (example). An example info directory entry.
9083 to the Texinfo source of the document and ensure that the info
9084 documents are rebuilt from source during the package build.
9090 <heading>Additional documentation</heading>
9093 Any additional documentation that comes with the package may
9094 be installed at the discretion of the package maintainer.
9095 Plain text documentation should be installed in the directory
9096 <file>/usr/share/doc/<var>package</var></file>, where
9097 <var>package</var> is the name of the package, and
9098 compressed with <tt>gzip -9</tt> unless it is small.
9102 If a package comes with large amounts of documentation which
9103 many users of the package will not require you should create
9104 a separate binary package to contain it, so that it does not
9105 take up disk space on the machines of users who do not need
9106 or want it installed.</p>
9109 It is often a good idea to put text information files
9110 (<file>README</file>s, changelogs, and so forth) that come with
9111 the source package in <file>/usr/share/doc/<var>package</var></file>
9112 in the binary package. However, you don't need to install
9113 the instructions for building and installing the package, of
9117 Packages must not require the existence of any files in
9118 <file>/usr/share/doc/</file> in order to function
9120 The system administrator should be able to
9121 delete files in <file>/usr/share/doc/</file> without causing
9122 any programs to break.
9124 Any files that are referenced by programs but are also
9125 useful as stand alone documentation should be installed under
9126 <file>/usr/share/<var>package</var>/</file> with symbolic links from
9127 <file>/usr/share/doc/<var>package</var></file>.
9131 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9132 link to another directory in <file>/usr/share/doc</file> only if
9133 the two packages both come from the same source and the
9134 first package Depends on the second.<footnote>
9136 Please note that this does not override the section on
9137 changelog files below, so the file
9138 <file>/usr/share/doc/<var>package</var>/changelog.Debian.gz</file>
9139 must refer to the changelog for the current version of
9140 <var>package</var> in question. In practice, this means
9141 that the sources of the target and the destination of the
9142 symlink must be the same (same source package and
9149 Former Debian releases placed all additional documentation
9150 in <file>/usr/doc/<var>package</var></file>. This has been
9151 changed to <file>/usr/share/doc/<var>package</var></file>,
9152 and packages must not put documentation in the directory
9153 <file>/usr/doc/<var>package</var></file>. <footnote>
9154 At this phase of the transition, we no longer require a
9155 symbolic link in <file>/usr/doc/</file>. At a later point,
9156 policy shall change to make the symbolic links a bug.
9162 <heading>Preferred documentation formats</heading>
9165 The unification of Debian documentation is being carried out
9169 If your package comes with extensive documentation in a
9170 markup format that can be converted to various other formats
9171 you should if possible ship HTML versions in a binary
9172 package, in the directory
9173 <file>/usr/share/doc/<var>appropriate-package</var></file> or
9174 its subdirectories.<footnote>
9175 The rationale: The important thing here is that HTML
9176 docs should be available in <em>some</em> package, not
9177 necessarily in the main binary package.
9182 Other formats such as PostScript may be provided at the
9183 package maintainer's discretion.
9187 <sect id="copyrightfile">
9188 <heading>Copyright information</heading>
9191 Every package must be accompanied by a verbatim copy of its
9192 copyright information and distribution license in the file
9193 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
9194 file must neither be compressed nor be a symbolic link.
9198 In addition, the copyright file must say where the upstream
9199 sources (if any) were obtained. It should name the original
9200 authors of the package and the Debian maintainer(s) who were
9201 involved with its creation.
9205 Packages in the <em>contrib</em> or <em>non-free</em> archive
9206 areas should state in the copyright file that the package is not
9207 part of the Debian GNU/Linux distribution and briefly explain
9212 A copy of the file which will be installed in
9213 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9214 be in <file>debian/copyright</file> in the source package.
9218 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9219 link to another directory in <file>/usr/share/doc</file> only if
9220 the two packages both come from the same source and the
9221 first package Depends on the second. These rules are
9222 important because copyrights must be extractable by
9227 Packages distributed under the UCB BSD license, the Apache
9228 license (version 2.0), the Artistic license, the GNU GPL
9229 (version 2 or 3), the GNU LGPL (versions 2, 2.1, or 3), and the
9230 GNU FDL (versions 1.2 or 1.3) should refer to the corresponding
9231 files under <file>/usr/share/common-licenses</file>,<footnote>
9234 <file>/usr/share/common-licenses/BSD</file>,
9235 <file>/usr/share/common-licenses/Apache-2.0</file>,
9236 <file>/usr/share/common-licenses/Artistic</file>,
9237 <file>/usr/share/common-licenses/GPL-2</file>,
9238 <file>/usr/share/common-licenses/GPL-3</file>,
9239 <file>/usr/share/common-licenses/LGPL-2</file>,
9240 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9241 <file>/usr/share/common-licenses/LGPL-3</file>,
9242 <file>/usr/share/common-licenses/GFDL-1.2</file>, and
9243 <file>/usr/share/common-licenses/GFDL-1.3</file>
9246 </footnote> rather than quoting them in the copyright
9251 You should not use the copyright file as a general <file>README</file>
9252 file. If your package has such a file it should be
9253 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9254 <file>README.Debian</file> or some other appropriate place.</p>
9258 <heading>Examples</heading>
9261 Any examples (configurations, source files, whatever),
9262 should be installed in a directory
9263 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9264 files should not be referenced by any program: they're there
9265 for the benefit of the system administrator and users as
9266 documentation only. Architecture-specific example files
9267 should be installed in a directory
9268 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9270 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9271 latter directory itself may be a symbolic link to the
9276 If the purpose of a package is to provide examples, then the
9277 example files may be installed into
9278 <file>/usr/share/doc/<var>package</var></file>.
9282 <sect id="changelogs">
9283 <heading>Changelog files</heading>
9286 Packages that are not Debian-native must contain a
9287 compressed copy of the <file>debian/changelog</file> file from
9288 the Debian source tree in
9289 <file>/usr/share/doc/<var>package</var></file> with the name
9290 <file>changelog.Debian.gz</file>.
9294 If an upstream changelog is available, it should be accessible as
9295 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9296 plain text. If the upstream changelog is distributed in
9297 HTML, it should be made available in that form as
9298 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9299 and a plain text <file>changelog.gz</file> should be generated
9300 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9301 the upstream changelog files do not already conform to this
9302 naming convention, then this may be achieved either by
9303 renaming the files, or by adding a symbolic link, at the
9304 maintainer's discretion.<footnote>
9305 Rationale: People should not have to look in places for
9306 upstream changelogs merely because they are given
9307 different names or are distributed in HTML format.
9312 All of these files should be installed compressed using
9313 <tt>gzip -9</tt>, as they will become large with time even
9314 if they start out small.
9318 If the package has only one changelog which is used both as
9319 the Debian changelog and the upstream one because there is
9320 no separate upstream maintainer then that changelog should
9321 usually be installed as
9322 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9323 there is a separate upstream maintainer, but no upstream
9324 changelog, then the Debian changelog should still be called
9325 <file>changelog.Debian.gz</file>.
9329 For details about the format and contents of the Debian
9330 changelog file, please see <ref id="dpkgchangelog">.
9335 <appendix id="pkg-scope">
9336 <heading>Introduction and scope of these appendices</heading>
9339 These appendices are taken essentially verbatim from the
9340 now-deprecated Packaging Manual, version 3.2.1.0. They are
9341 the chapters which are likely to be of use to package
9342 maintainers and which have not already been included in the
9343 policy document itself. Most of these sections are very likely
9344 not relevant to policy; they should be treated as
9345 documentation for the packaging system. Please note that these
9346 appendices are included for convenience, and for historical
9347 reasons: they used to be part of policy package, and they have
9348 not yet been incorporated into dpkg documentation. However,
9349 they still have value, and hence they are presented here.
9353 They have not yet been checked to ensure that they are
9354 compatible with the contents of policy, and if there are any
9355 contradictions, the version in the main policy document takes
9356 precedence. The remaining chapters of the old Packaging
9357 Manual have also not been read in detail to ensure that there
9358 are not parts which have been left out. Both of these will be
9363 Certain parts of the Packaging manual were integrated into the
9364 Policy Manual proper, and removed from the appendices. Links
9365 have been placed from the old locations to the new ones.
9369 <prgn>dpkg</prgn> is a suite of programs for creating binary
9370 package files and installing and removing them on Unix
9372 <prgn>dpkg</prgn> is targeted primarily at Debian
9373 GNU/Linux, but may work on or be ported to other
9379 The binary packages are designed for the management of
9380 installed executable programs (usually compiled binaries) and
9381 their associated data, though source code examples and
9382 documentation are provided as part of some packages.</p>
9385 This manual describes the technical aspects of creating Debian
9386 binary packages (<file>.deb</file> files). It documents the
9387 behavior of the package management programs
9388 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9389 they interact with packages.</p>
9392 It also documents the interaction between
9393 <prgn>dselect</prgn>'s core and the access method scripts it
9394 uses to actually install the selected packages, and describes
9395 how to create a new access method.</p>
9398 This manual does not go into detail about the options and
9399 usage of the package building and installation tools. It
9400 should therefore be read in conjunction with those programs'
9405 The utility programs which are provided with <prgn>dpkg</prgn>
9406 for managing various system configuration and similar issues,
9407 such as <prgn>update-rc.d</prgn> and
9408 <prgn>install-info</prgn>, are not described in detail here -
9409 please see their man pages.
9413 It is assumed that the reader is reasonably familiar with the
9414 <prgn>dpkg</prgn> System Administrators' manual.
9415 Unfortunately this manual does not yet exist.
9419 The Debian version of the FSF's GNU hello program is provided
9420 as an example for people wishing to create Debian
9421 packages. The Debian <prgn>debmake</prgn> package is
9422 recommended as a very helpful tool in creating and maintaining
9423 Debian packages. However, while the tools and examples are
9424 helpful, they do not replace the need to read and follow the
9425 Policy and Programmer's Manual.</p>
9428 <appendix id="pkg-binarypkg">
9429 <heading>Binary packages (from old Packaging Manual)</heading>
9432 The binary package has two main sections. The first part
9433 consists of various control information files and scripts used
9434 by <prgn>dpkg</prgn> when installing and removing. See <ref
9435 id="pkg-controlarea">.
9439 The second part is an archive containing the files and
9440 directories to be installed.
9444 In the future binary packages may also contain other
9445 components, such as checksums and digital signatures. The
9446 format for the archive is described in full in the
9447 <file>deb(5)</file> man page.
9451 <sect id="pkg-bincreating"><heading>Creating package files -
9452 <prgn>dpkg-deb</prgn>
9456 All manipulation of binary package files is done by
9457 <prgn>dpkg-deb</prgn>; it's the only program that has
9458 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9459 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9460 will spot that the options requested are appropriate to
9461 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9466 In order to create a binary package you must make a
9467 directory tree which contains all the files and directories
9468 you want to have in the file system data part of the package.
9469 In Debian-format source packages this directory is usually
9470 <file>debian/tmp</file>, relative to the top of the package's
9475 They should have the locations (relative to the root of the
9476 directory tree you're constructing) ownerships and
9477 permissions which you want them to have on the system when
9482 With current versions of <prgn>dpkg</prgn> the uid/username
9483 and gid/groupname mappings for the users and groups being
9484 used should be the same on the system where the package is
9485 built and the one where it is installed.
9489 You need to add one special directory to the root of the
9490 miniature file system tree you're creating:
9491 <prgn>DEBIAN</prgn>. It should contain the control
9492 information files, notably the binary package control file
9493 (see <ref id="pkg-controlfile">).
9497 The <prgn>DEBIAN</prgn> directory will not appear in the
9498 file system archive of the package, and so won't be installed
9499 by <prgn>dpkg</prgn> when the package is installed.
9503 When you've prepared the package, you should invoke:
9505 dpkg --build <var>directory</var>
9510 This will build the package in
9511 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9512 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9513 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9518 See the man page <manref name="dpkg-deb" section="8"> for details of how
9519 to examine the contents of this newly-created file. You may find the
9520 output of following commands enlightening:
9522 dpkg-deb --info <var>filename</var>.deb
9523 dpkg-deb --contents <var>filename</var>.deb
9524 dpkg --contents <var>filename</var>.deb
9526 To view the copyright file for a package you could use this command:
9528 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
9533 <sect id="pkg-controlarea">
9534 <heading>Package control information files</heading>
9537 The control information portion of a binary package is a
9538 collection of files with names known to <prgn>dpkg</prgn>.
9539 It will treat the contents of these files specially - some
9540 of them contain information used by <prgn>dpkg</prgn> when
9541 installing or removing the package; others are scripts which
9542 the package maintainer wants <prgn>dpkg</prgn> to run.
9546 It is possible to put other files in the package control
9547 area, but this is not generally a good idea (though they
9548 will largely be ignored).
9552 Here is a brief list of the control info files supported by
9553 <prgn>dpkg</prgn> and a summary of what they're used for.
9558 <tag><tt>control</tt>
9561 This is the key description file used by
9562 <prgn>dpkg</prgn>. It specifies the package's name
9563 and version, gives its description for the user,
9564 states its relationships with other packages, and so
9565 forth. See <ref id="sourcecontrolfiles"> and
9566 <ref id="binarycontrolfiles">.
9570 It is usually generated automatically from information
9571 in the source package by the
9572 <prgn>dpkg-gencontrol</prgn> program, and with
9573 assistance from <prgn>dpkg-shlibdeps</prgn>.
9574 See <ref id="pkg-sourcetools">.
9578 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9583 These are executable files (usually scripts) which
9584 <prgn>dpkg</prgn> runs during installation, upgrade
9585 and removal of packages. They allow the package to
9586 deal with matters which are particular to that package
9587 or require more complicated processing than that
9588 provided by <prgn>dpkg</prgn>. Details of when and
9589 how they are called are in <ref id="maintainerscripts">.
9593 It is very important to make these scripts idempotent.
9594 See <ref id="idempotency">.
9598 The maintainer scripts are guaranteed to run with a
9599 controlling terminal and can interact with the user.
9600 See <ref id="controllingterminal">.
9604 <tag><tt>conffiles</tt>
9607 This file contains a list of configuration files which
9608 are to be handled automatically by <prgn>dpkg</prgn>
9609 (see <ref id="pkg-conffiles">). Note that not necessarily
9610 every configuration file should be listed here.
9613 <tag><tt>shlibs</tt>
9616 This file contains a list of the shared libraries
9617 supplied by the package, with dependency details for
9618 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9619 when it determines what dependencies are required in a
9620 package control file. The <tt>shlibs</tt> file format
9621 is described on <ref id="shlibs">.
9626 <sect id="pkg-controlfile">
9627 <heading>The main control information file: <tt>control</tt></heading>
9630 The most important control information file used by
9631 <prgn>dpkg</prgn> when it installs a package is
9632 <tt>control</tt>. It contains all the package's "vital
9637 The binary package control files of packages built from
9638 Debian sources are made by a special tool,
9639 <prgn>dpkg-gencontrol</prgn>, which reads
9640 <file>debian/control</file> and <file>debian/changelog</file> to
9641 find the information it needs. See <ref id="pkg-sourcepkg"> for
9646 The fields in binary package control files are listed in
9647 <ref id="binarycontrolfiles">.
9651 A description of the syntax of control files and the purpose
9652 of the fields is available in <ref id="controlfields">.
9657 <heading>Time Stamps</heading>
9660 See <ref id="timestamps">.
9665 <appendix id="pkg-sourcepkg">
9666 <heading>Source packages (from old Packaging Manual) </heading>
9669 The Debian binary packages in the distribution are generated
9670 from Debian sources, which are in a special format to assist
9671 the easy and automatic building of binaries.
9674 <sect id="pkg-sourcetools">
9675 <heading>Tools for processing source packages</heading>
9678 Various tools are provided for manipulating source packages;
9679 they pack and unpack sources and help build of binary
9680 packages and help manage the distribution of new versions.
9684 They are introduced and typical uses described here; see
9685 <manref name="dpkg-source" section="1"> for full
9686 documentation about their arguments and operation.
9690 For examples of how to construct a Debian source package,
9691 and how to use those utilities that are used by Debian
9692 source packages, please see the <prgn>hello</prgn> example
9696 <sect1 id="pkg-dpkg-source">
9698 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
9703 This program is frequently used by hand, and is also
9704 called from package-independent automated building scripts
9705 such as <prgn>dpkg-buildpackage</prgn>.
9709 To unpack a package it is typically invoked with
9711 dpkg-source -x <var>.../path/to/filename</var>.dsc
9716 with the <file><var>filename</var>.tar.gz</file> and
9717 <file><var>filename</var>.diff.gz</file> (if applicable) in
9718 the same directory. It unpacks into
9719 <file><var>package</var>-<var>version</var></file>, and if
9721 <file><var>package</var>-<var>version</var>.orig</file>, in
9722 the current directory.
9726 To create a packed source archive it is typically invoked:
9728 dpkg-source -b <var>package</var>-<var>version</var>
9733 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
9734 <file>.diff.gz</file> (if appropriate) in the current
9735 directory. <prgn>dpkg-source</prgn> does not clean the
9736 source tree first - this must be done separately if it is
9741 See also <ref id="pkg-sourcearchives">.</p>
9745 <sect1 id="pkg-dpkg-buildpackage">
9747 <prgn>dpkg-buildpackage</prgn> - overall package-building
9752 <prgn>dpkg-buildpackage</prgn> is a script which invokes
9753 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
9754 targets <tt>clean</tt>, <tt>build</tt> and
9755 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
9756 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
9757 source and binary package upload.
9761 It is usually invoked by hand from the top level of the
9762 built or unbuilt source directory. It may be invoked with
9763 no arguments; useful arguments include:
9764 <taglist compact="compact">
9765 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
9768 Do not sign the <tt>.changes</tt> file or the
9769 source package <tt>.dsc</tt> file, respectively.</p>
9771 <tag><tt>-p<var>sign-command</var></tt></tag>
9774 Invoke <var>sign-command</var> instead of finding
9775 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
9776 <var>sign-command</var> must behave just like
9777 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9779 <tag><tt>-r<var>root-command</var></tt></tag>
9782 When root privilege is required, invoke the command
9783 <var>root-command</var>. <var>root-command</var>
9784 should invoke its first argument as a command, from
9785 the <prgn>PATH</prgn> if necessary, and pass its
9786 second and subsequent arguments to the command it
9787 calls. If no <var>root-command</var> is supplied
9788 then <var>dpkg-buildpackage</var> will take no
9789 special action to gain root privilege, so that for
9790 most packages it will have to be invoked as root to
9793 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9796 Two types of binary-only build and upload - see
9797 <manref name="dpkg-source" section="1">.
9804 <sect1 id="pkg-dpkg-gencontrol">
9806 <prgn>dpkg-gencontrol</prgn> - generates binary package
9811 This program is usually called from <file>debian/rules</file>
9812 (see <ref id="pkg-sourcetree">) in the top level of the source
9817 This is usually done just before the files and directories in the
9818 temporary directory tree where the package is being built have their
9819 permissions and ownerships set and the package is constructed using
9820 <prgn>dpkg-deb/</prgn>
9822 This is so that the control file which is produced has
9823 the right permissions
9828 <prgn>dpkg-gencontrol</prgn> must be called after all the
9829 files which are to go into the package have been placed in
9830 the temporary build directory, so that its calculation of
9831 the installed size of a package is correct.
9835 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9836 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9837 variable substitutions created by
9838 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9843 For a package which generates only one binary package, and
9844 which builds it in <file>debian/tmp</file> relative to the top
9845 of the source package, it is usually sufficient to call
9846 <prgn>dpkg-gencontrol</prgn>.
9850 Sources which build several binaries will typically need
9853 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9854 </example> The <tt>-P</tt> tells
9855 <prgn>dpkg-gencontrol</prgn> that the package is being
9856 built in a non-default directory, and the <tt>-p</tt>
9857 tells it which package's control file should be generated.
9861 <prgn>dpkg-gencontrol</prgn> also adds information to the
9862 list of files in <file>debian/files</file>, for the benefit of
9863 (for example) a future invocation of
9864 <prgn>dpkg-genchanges</prgn>.</p>
9867 <sect1 id="pkg-dpkg-shlibdeps">
9869 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9874 This program is usually called from <file>debian/rules</file>
9875 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9876 id="pkg-sourcetree">), in the top level of the source tree.
9880 Its arguments are executables and shared libraries
9883 They may be specified either in the locations in the
9884 source tree where they are created or in the locations
9885 in the temporary build tree where they are installed
9886 prior to binary package creation.
9888 </footnote> for which shared library dependencies should
9889 be included in the binary package's control file.
9893 If some of the found shared libraries should only
9894 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9895 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9896 by using the <tt>-d<var>dependency-field</var></tt> option
9897 before those executable(s). (Each <tt>-d</tt> option
9898 takes effect until the next <tt>-d</tt>.)
9902 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9903 output control file to be modified. Instead by default it
9904 adds to the <file>debian/substvars</file> file variable
9905 settings like <tt>shlibs:Depends</tt>. These variable
9906 settings must be referenced in dependency fields in the
9907 appropriate per-binary-package sections of the source
9912 For example, a package that generates an essential part
9913 which requires dependencies, and optional parts that
9914 which only require a recommendation, would separate those
9915 two sets of dependencies into two different fields.<footnote>
9916 At the time of writing, an example for this was the
9917 <package/xmms/ package, with Depends used for the xmms
9918 executable, Recommends for the plug-ins and Suggests for
9919 even more optional features provided by unzip.
9921 It can say in its <file>debian/rules</file>:
9923 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9924 -dRecommends <var>optionalpart anotheroptionalpart</var>
9926 and then in its main control file <file>debian/control</file>:
9929 Depends: ${shlibs:Depends}
9930 Recommends: ${shlibs:Recommends}
9936 Sources which produce several binary packages with
9937 different shared library dependency requirements can use
9938 the <tt>-p<var>varnameprefix</var></tt> option to override
9939 the default <tt>shlibs:</tt> prefix (one invocation of
9940 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9941 They can thus produce several sets of dependency
9942 variables, each of the form
9943 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9944 which can be referred to in the appropriate parts of the
9945 binary package control files.
9950 <sect1 id="pkg-dpkg-distaddfile">
9952 <prgn>dpkg-distaddfile</prgn> - adds a file to
9953 <file>debian/files</file>
9957 Some packages' uploads need to include files other than
9958 the source and binary package files.
9962 <prgn>dpkg-distaddfile</prgn> adds a file to the
9963 <file>debian/files</file> file so that it will be included in
9964 the <file>.changes</file> file when
9965 <prgn>dpkg-genchanges</prgn> is run.
9969 It is usually invoked from the <tt>binary</tt> target of
9970 <file>debian/rules</file>:
9972 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9974 The <var>filename</var> is relative to the directory where
9975 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9976 is usually the directory above the top level of the source
9977 tree. The <file>debian/rules</file> target should put the
9978 file there just before or just after calling
9979 <prgn>dpkg-distaddfile</prgn>.
9983 The <var>section</var> and <var>priority</var> are passed
9984 unchanged into the resulting <file>.changes</file> file.
9989 <sect1 id="pkg-dpkg-genchanges">
9991 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9996 This program is usually called by package-independent
9997 automatic building scripts such as
9998 <prgn>dpkg-buildpackage</prgn>, but it may also be called
10003 It is usually called in the top level of a built source
10004 tree, and when invoked with no arguments will print out a
10005 straightforward <file>.changes</file> file based on the
10006 information in the source package's changelog and control
10007 file and the binary and source packages which should have
10013 <sect1 id="pkg-dpkg-parsechangelog">
10015 <prgn>dpkg-parsechangelog</prgn> - produces parsed
10016 representation of a changelog
10020 This program is used internally by
10021 <prgn>dpkg-source</prgn> et al. It may also occasionally
10022 be useful in <file>debian/rules</file> and elsewhere. It
10023 parses a changelog, <file>debian/changelog</file> by default,
10024 and prints a control-file format representation of the
10025 information in it to standard output.
10029 <sect1 id="pkg-dpkg-architecture">
10031 <prgn>dpkg-architecture</prgn> - information about the build and
10036 This program can be used manually, but is also invoked by
10037 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
10038 environment or make variables which specify the build and host
10039 architecture for the package building process.
10044 <sect id="pkg-sourcetree">
10045 <heading>The Debianised source tree</heading>
10048 The source archive scheme described later is intended to
10049 allow a Debianised source tree with some associated control
10050 information to be reproduced and transported easily. The
10051 Debianised source tree is a version of the original program
10052 with certain files added for the benefit of the
10053 Debianisation process, and with any other changes required
10054 made to the rest of the source code and installation
10059 The extra files created for Debian are in the subdirectory
10060 <file>debian</file> of the top level of the Debianised source
10061 tree. They are described below.
10064 <sect1 id="pkg-debianrules">
10065 <heading><file>debian/rules</file> - the main building script</heading>
10068 See <ref id="debianrules">.
10072 <sect1 id="pkg-srcsubstvars">
10073 <heading><file>debian/substvars</file> and variable substitutions</heading>
10076 See <ref id="substvars">.
10082 <heading><file>debian/files</file></heading>
10085 See <ref id="debianfiles">.
10089 <sect1><heading><file>debian/tmp</file>
10093 This is the canonical temporary location for the
10094 construction of binary packages by the <tt>binary</tt>
10095 target. The directory <file>tmp</file> serves as the root of
10096 the file system tree as it is being constructed (for
10097 example, by using the package's upstream makefiles install
10098 targets and redirecting the output there), and it also
10099 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10100 id="pkg-bincreating">.
10104 If several binary packages are generated from the same
10105 source tree it is usual to use several
10106 <file>debian/tmp<var>something</var></file> directories, for
10107 example <file>tmp-a</file> or <file>tmp-doc</file>.
10111 Whatever <file>tmp</file> directories are created and used by
10112 <tt>binary</tt> must of course be removed by the
10113 <tt>clean</tt> target.</p></sect1>
10117 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10121 As it exists on the FTP site, a Debian source package
10122 consists of three related files. You must have the right
10123 versions of all three to be able to use them.
10128 <tag>Debian source control file - <tt>.dsc</tt></tag>
10130 This file is a control file used by <prgn>dpkg-source</prgn>
10131 to extract a source package.
10132 See <ref id="debiansourcecontrolfiles">.
10136 Original source archive -
10138 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10144 This is a compressed (with <tt>gzip -9</tt>)
10145 <prgn>tar</prgn> file containing the source code from
10146 the upstream authors of the program.
10151 Debianisation diff -
10153 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10159 This is a unified context diff (<tt>diff -u</tt>)
10160 giving the changes which are required to turn the
10161 original source into the Debian source. These changes
10162 may only include editing and creating plain files.
10163 The permissions of files, the targets of symbolic
10164 links and the characteristics of special files or
10165 pipes may not be changed and no files may be removed
10170 All the directories in the diff must exist, except the
10171 <file>debian</file> subdirectory of the top of the source
10172 tree, which will be created by
10173 <prgn>dpkg-source</prgn> if necessary when unpacking.
10177 The <prgn>dpkg-source</prgn> program will
10178 automatically make the <file>debian/rules</file> file
10179 executable (see below).</p></item>
10184 If there is no original source code - for example, if the
10185 package is specially prepared for Debian or the Debian
10186 maintainer is the same as the upstream maintainer - the
10187 format is slightly different: then there is no diff, and the
10189 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10190 and preferably contains a directory named
10191 <file><var>package</var>-<var>version</var></file>.
10196 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10199 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10200 Debian source package. However, if it is not available it
10201 is possible to unpack a Debian source archive as follows:
10202 <enumlist compact="compact">
10205 Untar the tarfile, which will create a <file>.orig</file>
10209 <p>Rename the <file>.orig</file> directory to
10210 <file><var>package</var>-<var>version</var></file>.</p>
10214 Create the subdirectory <file>debian</file> at the top of
10215 the source tree.</p>
10217 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10219 <item><p>Untar the tarfile again if you want a copy of the original
10220 source code alongside the Debianised version.</p>
10225 It is not possible to generate a valid Debian source archive
10226 without using <prgn>dpkg-source</prgn>. In particular,
10227 attempting to use <prgn>diff</prgn> directly to generate the
10228 <file>.diff.gz</file> file will not work.
10232 <heading>Restrictions on objects in source packages</heading>
10235 The source package may not contain any hard links
10237 This is not currently detected when building source
10238 packages, but only when extracting
10242 Hard links may be permitted at some point in the
10243 future, but would require a fair amount of
10245 </footnote>, device special files, sockets or setuid or
10248 Setgid directories are allowed.
10253 The source packaging tools manage the changes between the
10254 original and Debianised source using <prgn>diff</prgn> and
10255 <prgn>patch</prgn>. Turning the original source tree as
10256 included in the <file>.orig.tar.gz</file> into the debianised
10257 source must not involve any changes which cannot be
10258 handled by these tools. Problematic changes which cause
10259 <prgn>dpkg-source</prgn> to halt with an error when
10260 building the source package are:
10261 <list compact="compact">
10262 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10264 <item><p>Changing the targets of symbolic links.</p>
10266 <item><p>Creating directories, other than <file>debian</file>.</p>
10268 <item><p>Changes to the contents of binary files.</p></item>
10269 </list> Changes which cause <prgn>dpkg-source</prgn> to
10270 print a warning but continue anyway are:
10271 <list compact="compact">
10274 Removing files, directories or symlinks.
10276 Renaming a file is not treated specially - it is
10277 seen as the removal of the old file (which
10278 generates a warning, but is otherwise ignored),
10279 and the creation of the new one.
10285 Changed text files which are missing the usual final
10286 newline (either in the original or the modified
10291 Changes which are not represented, but which are not detected by
10292 <prgn>dpkg-source</prgn>, are:
10293 <list compact="compact">
10294 <item><p>Changing the permissions of files (other than
10295 <file>debian/rules</file>) and directories.</p></item>
10300 The <file>debian</file> directory and <file>debian/rules</file>
10301 are handled specially by <prgn>dpkg-source</prgn> - before
10302 applying the changes it will create the <file>debian</file>
10303 directory, and afterwards it will make
10304 <file>debian/rules</file> world-executable.
10310 <appendix id="pkg-controlfields">
10311 <heading>Control files and their fields (from old Packaging Manual)</heading>
10314 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10315 data in a common format, known as control files. Binary and
10316 source packages have control data as do the <file>.changes</file>
10317 files which control the installation of uploaded files, and
10318 <prgn>dpkg</prgn>'s internal databases are in a similar
10323 <heading>Syntax of control files</heading>
10326 See <ref id="controlsyntax">.
10330 It is important to note that there are several fields which
10331 are optional as far as <prgn>dpkg</prgn> and the related
10332 tools are concerned, but which must appear in every Debian
10333 package, or whose omission may cause problems.
10338 <heading>List of fields</heading>
10341 See <ref id="controlfieldslist">.
10345 This section now contains only the fields that didn't belong
10346 to the Policy manual.
10349 <sect1 id="pkg-f-Filename">
10350 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10353 These fields in <tt>Packages</tt> files give the
10354 filename(s) of (the parts of) a package in the
10355 distribution directories, relative to the root of the
10356 Debian hierarchy. If the package has been split into
10357 several parts the parts are all listed in order, separated
10362 <sect1 id="pkg-f-Size">
10363 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10366 These fields in <file>Packages</file> files give the size (in
10367 bytes, expressed in decimal) and MD5 checksum of the
10368 file(s) which make(s) up a binary package in the
10369 distribution. If the package is split into several parts
10370 the values for the parts are listed in order, separated by
10375 <sect1 id="pkg-f-Status">
10376 <heading><tt>Status</tt></heading>
10379 This field in <prgn>dpkg</prgn>'s status file records
10380 whether the user wants a package installed, removed or
10381 left alone, whether it is broken (requiring
10382 re-installation) or not and what its current state on the
10383 system is. Each of these pieces of information is a
10388 <sect1 id="pkg-f-Config-Version">
10389 <heading><tt>Config-Version</tt></heading>
10392 If a package is not installed or not configured, this
10393 field in <prgn>dpkg</prgn>'s status file records the last
10394 version of the package which was successfully
10399 <sect1 id="pkg-f-Conffiles">
10400 <heading><tt>Conffiles</tt></heading>
10403 This field in <prgn>dpkg</prgn>'s status file contains
10404 information about the automatically-managed configuration
10405 files held by a package. This field should <em>not</em>
10406 appear anywhere in a package!
10411 <heading>Obsolete fields</heading>
10414 These are still recognized by <prgn>dpkg</prgn> but should
10415 not appear anywhere any more.
10417 <taglist compact="compact">
10419 <tag><tt>Revision</tt></tag>
10420 <tag><tt>Package-Revision</tt></tag>
10421 <tag><tt>Package_Revision</tt></tag>
10423 The Debian revision part of the package version was
10424 at one point in a separate control file field. This
10425 field went through several names.
10428 <tag><tt>Recommended</tt></tag>
10429 <item>Old name for <tt>Recommends</tt>.</item>
10431 <tag><tt>Optional</tt></tag>
10432 <item>Old name for <tt>Suggests</tt>.</item>
10434 <tag><tt>Class</tt></tag>
10435 <item>Old name for <tt>Priority</tt>.</item>
10444 <appendix id="pkg-conffiles">
10445 <heading>Configuration file handling (from old Packaging Manual)</heading>
10448 <prgn>dpkg</prgn> can do a certain amount of automatic
10449 handling of package configuration files.
10453 Whether this mechanism is appropriate depends on a number of
10454 factors, but basically there are two approaches to any
10455 particular configuration file.
10459 The easy method is to ship a best-effort configuration in the
10460 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10461 handle updates. If the user is unlikely to want to edit the
10462 file, but you need them to be able to without losing their
10463 changes, and a new package with a changed version of the file
10464 is only released infrequently, this is a good approach.
10468 The hard method is to build the configuration file from
10469 scratch in the <prgn>postinst</prgn> script, and to take the
10470 responsibility for fixing any mistakes made in earlier
10471 versions of the package automatically. This will be
10472 appropriate if the file is likely to need to be different on
10476 <sect><heading>Automatic handling of configuration files by
10481 A package may contain a control area file called
10482 <tt>conffiles</tt>. This file should be a list of filenames
10483 of configuration files needing automatic handling, separated
10484 by newlines. The filenames should be absolute pathnames,
10485 and the files referred to should actually exist in the
10490 When a package is upgraded <prgn>dpkg</prgn> will process
10491 the configuration files during the configuration stage,
10492 shortly before it runs the package's <prgn>postinst</prgn>
10497 For each file it checks to see whether the version of the
10498 file included in the package is the same as the one that was
10499 included in the last version of the package (the one that is
10500 being upgraded from); it also compares the version currently
10501 installed on the system with the one shipped with the last
10506 If neither the user nor the package maintainer has changed
10507 the file, it is left alone. If one or the other has changed
10508 their version, then the changed version is preferred - i.e.,
10509 if the user edits their file, but the package maintainer
10510 doesn't ship a different version, the user's changes will
10511 stay, silently, but if the maintainer ships a new version
10512 and the user hasn't edited it the new version will be
10513 installed (with an informative message). If both have
10514 changed their version the user is prompted about the problem
10515 and must resolve the differences themselves.
10519 The comparisons are done by calculating the MD5 message
10520 digests of the files, and storing the MD5 of the file as it
10521 was included in the most recent version of the package.
10525 When a package is installed for the first time
10526 <prgn>dpkg</prgn> will install the file that comes with it,
10527 unless that would mean overwriting a file already on the
10532 However, note that <prgn>dpkg</prgn> will <em>not</em>
10533 replace a conffile that was removed by the user (or by a
10534 script). This is necessary because with some programs a
10535 missing file produces an effect hard or impossible to
10536 achieve in another way, so that a missing file needs to be
10537 kept that way if the user did it.
10541 Note that a package should <em>not</em> modify a
10542 <prgn>dpkg</prgn>-handled conffile in its maintainer
10543 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10544 the user confusing and possibly dangerous options for
10545 conffile update when the package is upgraded.</p>
10548 <sect><heading>Fully-featured maintainer script configuration
10553 For files which contain site-specific information such as
10554 the hostname and networking details and so forth, it is
10555 better to create the file in the package's
10556 <prgn>postinst</prgn> script.
10560 This will typically involve examining the state of the rest
10561 of the system to determine values and other information, and
10562 may involve prompting the user for some information which
10563 can't be obtained some other way.
10567 When using this method there are a couple of important
10568 issues which should be considered:
10572 If you discover a bug in the program which generates the
10573 configuration file, or if the format of the file changes
10574 from one version to the next, you will have to arrange for
10575 the postinst script to do something sensible - usually this
10576 will mean editing the installed configuration file to remove
10577 the problem or change the syntax. You will have to do this
10578 very carefully, since the user may have changed the file,
10579 perhaps to fix the very problem that your script is trying
10580 to deal with - you will have to detect these situations and
10581 deal with them correctly.
10585 If you do go down this route it's probably a good idea to
10586 make the program that generates the configuration file(s) a
10587 separate program in <file>/usr/sbin</file>, by convention called
10588 <file><var>package</var>config</file> and then run that if
10589 appropriate from the post-installation script. The
10590 <tt><var>package</var>config</tt> program should not
10591 unquestioningly overwrite an existing configuration - if its
10592 mode of operation is geared towards setting up a package for
10593 the first time (rather than any arbitrary reconfiguration
10594 later) you should have it check whether the configuration
10595 already exists, and require a <tt>--force</tt> flag to
10596 overwrite it.</p></sect>
10599 <appendix id="pkg-alternatives"><heading>Alternative versions of
10600 an interface - <prgn>update-alternatives</prgn> (from old
10605 When several packages all provide different versions of the
10606 same program or file it is useful to have the system select a
10607 default, but to allow the system administrator to change it
10608 and have their decisions respected.
10612 For example, there are several versions of the <prgn>vi</prgn>
10613 editor, and there is no reason to prevent all of them from
10614 being installed at once, each under their own name
10615 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10616 Nevertheless it is desirable to have the name <tt>vi</tt>
10617 refer to something, at least by default.
10621 If all the packages involved cooperate, this can be done with
10622 <prgn>update-alternatives</prgn>.
10626 Each package provides its own version under its own name, and
10627 calls <prgn>update-alternatives</prgn> in its postinst to
10628 register its version (and again in its prerm to deregister
10633 See the man page <manref name="update-alternatives"
10634 section="8"> for details.
10638 If <prgn>update-alternatives</prgn> does not seem appropriate
10639 you may wish to consider using diversions instead.</p>
10642 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10643 package's version of a file (from old Packaging Manual)
10647 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10648 when it reinstalls the package it belongs to, and to have it
10649 put the file from the package somewhere else instead.
10653 This can be used locally to override a package's version of a
10654 file, or by one package to override another's version (or
10655 provide a wrapper for it).
10659 Before deciding to use a diversion, read <ref
10660 id="pkg-alternatives"> to see if you really want a diversion
10661 rather than several alternative versions of a program.
10665 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10666 and updated by a special program <prgn>dpkg-divert</prgn>.
10667 Please see <manref name="dpkg-divert" section="8"> for full
10668 details of its operation.
10672 When a package wishes to divert a file from another, it should
10673 call <prgn>dpkg-divert</prgn> in its preinst to add the
10674 diversion and rename the existing file. For example,
10675 supposing that a <prgn>smailwrapper</prgn> package wishes to
10676 install a wrapper around <file>/usr/sbin/smail</file>:
10678 dpkg-divert --package smailwrapper --add --rename \
10679 --divert /usr/sbin/smail.real /usr/sbin/smail
10680 </example> The <tt>--package smailwrapper</tt> ensures that
10681 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
10682 can bypass the diversion and get installed as the true version.
10683 It's safe to add the diversion unconditionally on upgrades since
10684 it will be left unchanged if it already exists, but
10685 <prgn>dpkg-divert</prgn> will display a message. To suppress that
10686 message, make the command conditional on the version from which
10687 the package is being upgraded:
10689 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
10690 dpkg-divert --package smailwrapper --add --rename \
10691 --divert /usr/sbin/smail.real /usr/sbin/smail
10693 </example> where <tt>1.0-2</tt> is the version at which the
10694 diversion was first added to the package. Running the command
10695 during abort-upgrade is pointless but harmless.
10699 The postrm has to do the reverse:
10701 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
10702 dpkg-divert --package smailwrapper --remove --rename \
10703 --divert /usr/sbin/smail.real /usr/sbin/smail
10705 </example> If the diversion was added at a particular version, the
10706 postrm should also handle the failure case of upgrading from an
10707 older version (unless the older version is so old that direct
10708 upgrades are no longer supported):
10710 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
10711 dpkg-divert --package smailwrapper --remove --rename \
10712 --divert /usr/sbin/smail.real /usr/sbin/smail
10714 </example> where <tt>1.02-2</tt> is the version at which the
10715 diversion was first added to the package. The postrm should not
10716 remove the diversion on upgrades both because there's no reason to
10717 remove the diversion only to immediately re-add it and since the
10718 postrm of the old package is run after unpacking so the removal of
10719 the diversion will fail.
10723 Do not attempt to divert a file which is vitally important for
10724 the system's operation - when using <prgn>dpkg-divert</prgn>
10725 there is a time, after it has been diverted but before
10726 <prgn>dpkg</prgn> has installed the new version, when the file
10727 does not exist.</p>
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