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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">.
2747 <tt>all</tt>, which indicates an
2748 architecture-independent package.
2751 <tt>source</tt>, which indicates a source package.
2757 In the main <file>debian/control</file> file in the source
2758 package, this field may contain the special value <tt>all</tt>
2759 or a list of specific and wildcard architectures separated by
2760 spaces. If <tt>all</tt> appears, that value must be the
2761 entire contents of the field. Most packages will use
2762 either <tt>any</tt> or <tt>all</tt>. Specifying a specific
2763 list of architectures is for the minority of cases where a
2764 program is not portable or is not useful on some
2765 architectures, and where possible the program should be made
2770 Specifying a list of architecture wildcards indicates that
2771 the source will build an architecture-dependent package on
2772 the union of the lists of architectures from the expansion
2773 of each specified architecture wildcard, and will only
2774 work correctly on the architectures in the union of the
2776 Use of architecture wildcards other than <tt>all</tt> is for
2777 a minority of cases where the program is not portable and
2778 should not be used for most packages. Wildcards are not
2779 expanded into a list of known architectures before comparing
2780 to the build architecutre. Instead, the build architecture
2781 is matched against any wildcards and this package is built
2782 if any wildcard matches.
2787 In the source package control file <file>.dsc</file>, this
2788 field may contain either the special value <tt>any</tt> or a
2789 list of architectures separated by spaces. If a list is given,
2790 it may include (or consist solely of) the special value
2791 <tt>all</tt>. In other words, in <file>.dsc</file> files
2792 unlike the <file>debian/control</file>, <tt>all</tt> may occur
2793 in combination with specific architectures. The
2794 <tt>Architecture</tt> field in the source package control file
2795 <file>.dsc</file> is generally constructed from the
2796 <tt>Architecture</tt> fields in the
2797 <file>debian/control</file> in the source package.
2801 Specifying <tt>any</tt> indicates that the source package
2802 isn't dependent on any particular architecture and should
2803 compile fine on any one. The produced binary package(s)
2804 will either be specific to whatever the current build
2805 architecture is or will be architecture-independent.
2809 Specifying only <tt>all</tt> indicates that the source package
2810 will only build architecture-independent packages. If this is
2811 the case, <tt>all</tt> must be used rather than <tt>any</tt>;
2812 <tt>any</tt> implies that the source package will build at
2813 least one architecture-dependent package.
2817 Specifying a list of architectures or architecture wildcards
2818 indicates that the source will build an architecture-dependent
2819 package, and will only work correctly on the listed or
2820 matching architectures. If the source package also builds at
2821 least one architecture-independent package, <tt>all</tt> will
2822 also be included in the list.
2826 In a <file>.changes</file> file, the <tt>Architecture</tt>
2827 field lists the architecture(s) of the package(s) currently
2828 being uploaded. This will be a list; if the source for the
2829 package is also being uploaded, the special
2830 entry <tt>source</tt> is also present. <tt>all</tt> will be
2831 present if any architecture-independent packages are being
2832 uploaded. Architecture wildcards such as <tt>any</tt> may
2833 never occur in the <tt>Architecture</tt> field in
2834 the <file>.changes</file> file.
2838 See <ref id="debianrules"> for information on how to get
2839 the architecture for the build process.
2843 <sect1 id="f-Essential">
2844 <heading><tt>Essential</tt></heading>
2847 This is a boolean field which may occur only in the
2848 control file of a binary package or in a per-package fields
2849 paragraph of a main source control data file.
2853 If set to <tt>yes</tt> then the package management system
2854 will refuse to remove the package (upgrading and replacing
2855 it is still possible). The other possible value is <tt>no</tt>,
2856 which is the same as not having the field at all.
2861 <heading>Package interrelationship fields:
2862 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2863 <tt>Recommends</tt>, <tt>Suggests</tt>,
2864 <tt>Breaks</tt>, <tt>Conflicts</tt>,
2865 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2869 These fields describe the package's relationships with
2870 other packages. Their syntax and semantics are described
2871 in <ref id="relationships">.</p>
2874 <sect1 id="f-Standards-Version">
2875 <heading><tt>Standards-Version</tt></heading>
2878 The most recent version of the standards (the policy
2879 manual and associated texts) with which the package
2884 The version number has four components: major and minor
2885 version number and major and minor patch level. When the
2886 standards change in a way that requires every package to
2887 change the major number will be changed. Significant
2888 changes that will require work in many packages will be
2889 signaled by a change to the minor number. The major patch
2890 level will be changed for any change to the meaning of the
2891 standards, however small; the minor patch level will be
2892 changed when only cosmetic, typographical or other edits
2893 are made which neither change the meaning of the document
2894 nor affect the contents of packages.
2898 Thus only the first three components of the policy version
2899 are significant in the <em>Standards-Version</em> control
2900 field, and so either these three components or all four
2901 components may be specified.<footnote>
2902 In the past, people specified the full version number
2903 in the Standards-Version field, for example "2.3.0.0".
2904 Since minor patch-level changes don't introduce new
2905 policy, it was thought it would be better to relax
2906 policy and only require the first 3 components to be
2907 specified, in this example "2.3.0". All four
2908 components may still be used if someone wishes to do so.
2914 <sect1 id="f-Version">
2915 <heading><tt>Version</tt></heading>
2918 The version number of a package. The format is:
2919 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2923 The three components here are:
2925 <tag><var>epoch</var></tag>
2928 This is a single (generally small) unsigned integer. It
2929 may be omitted, in which case zero is assumed. If it is
2930 omitted then the <var>upstream_version</var> may not
2935 It is provided to allow mistakes in the version numbers
2936 of older versions of a package, and also a package's
2937 previous version numbering schemes, to be left behind.
2941 <tag><var>upstream_version</var></tag>
2944 This is the main part of the version number. It is
2945 usually the version number of the original ("upstream")
2946 package from which the <file>.deb</file> file has been made,
2947 if this is applicable. Usually this will be in the same
2948 format as that specified by the upstream author(s);
2949 however, it may need to be reformatted to fit into the
2950 package management system's format and comparison
2955 The comparison behavior of the package management system
2956 with respect to the <var>upstream_version</var> is
2957 described below. The <var>upstream_version</var>
2958 portion of the version number is mandatory.
2962 The <var>upstream_version</var> may contain only
2963 alphanumerics<footnote>
2964 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2966 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2967 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
2968 tilde) and should start with a digit. If there is no
2969 <var>debian_revision</var> then hyphens are not allowed;
2970 if there is no <var>epoch</var> then colons are not
2975 <tag><var>debian_revision</var></tag>
2978 This part of the version number specifies the version of
2979 the Debian package based on the upstream version. It
2980 may contain only alphanumerics and the characters
2981 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
2982 tilde) and is compared in the same way as the
2983 <var>upstream_version</var> is.
2987 It is optional; if it isn't present then the
2988 <var>upstream_version</var> may not contain a hyphen.
2989 This format represents the case where a piece of
2990 software was written specifically to be turned into a
2991 Debian package, and so there is only one "debianisation"
2992 of it and therefore no revision indication is required.
2996 It is conventional to restart the
2997 <var>debian_revision</var> at <tt>1</tt> each time the
2998 <var>upstream_version</var> is increased.
3002 The package management system will break the version
3003 number apart at the last hyphen in the string (if there
3004 is one) to determine the <var>upstream_version</var> and
3005 <var>debian_revision</var>. The absence of a
3006 <var>debian_revision</var> is equivalent to a
3007 <var>debian_revision</var> of <tt>0</tt>.
3014 When comparing two version numbers, first the <var>epoch</var>
3015 of each are compared, then the <var>upstream_version</var> if
3016 <var>epoch</var> is equal, and then <var>debian_revision</var>
3017 if <var>upstream_version</var> is also equal.
3018 <var>epoch</var> is compared numerically. The
3019 <var>upstream_version</var> and <var>debian_revision</var>
3020 parts are compared by the package management system using the
3021 following algorithm:
3025 The strings are compared from left to right.
3029 First the initial part of each string consisting entirely of
3030 non-digit characters is determined. These two parts (one of
3031 which may be empty) are compared lexically. If a difference
3032 is found it is returned. The lexical comparison is a
3033 comparison of ASCII values modified so that all the letters
3034 sort earlier than all the non-letters and so that a tilde
3035 sorts before anything, even the end of a part. For example,
3036 the following parts are in sorted order from earliest to
3037 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
3038 <tt>a</tt>.<footnote>
3039 One common use of <tt>~</tt> is for upstream pre-releases.
3040 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
3041 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
3046 Then the initial part of the remainder of each string which
3047 consists entirely of digit characters is determined. The
3048 numerical values of these two parts are compared, and any
3049 difference found is returned as the result of the comparison.
3050 For these purposes an empty string (which can only occur at
3051 the end of one or both version strings being compared) counts
3056 These two steps (comparing and removing initial non-digit
3057 strings and initial digit strings) are repeated until a
3058 difference is found or both strings are exhausted.
3062 Note that the purpose of epochs is to allow us to leave behind
3063 mistakes in version numbering, and to cope with situations
3064 where the version numbering scheme changes. It is
3065 <em>not</em> intended to cope with version numbers containing
3066 strings of letters which the package management system cannot
3067 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
3068 silly orderings (the author of this manual has heard of a
3069 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
3070 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
3071 <tt>2</tt> and so forth).
3075 <sect1 id="f-Description">
3076 <heading><tt>Description</tt></heading>
3079 In a source or binary control file, the <tt>Description</tt>
3080 field contains a description of the binary package, consisting
3081 of two parts, the synopsis or the short description, and the
3082 long description. The field's format is as follows:
3087 Description: <single line synopsis>
3088 <extended description over several lines>
3093 The lines in the extended description can have these formats:
3099 Those starting with a single space are part of a paragraph.
3100 Successive lines of this form will be word-wrapped when
3101 displayed. The leading space will usually be stripped off.
3105 Those starting with two or more spaces. These will be
3106 displayed verbatim. If the display cannot be panned
3107 horizontally, the displaying program will line wrap them "hard"
3108 (i.e., without taking account of word breaks). If it can they
3109 will be allowed to trail off to the right. None, one or two
3110 initial spaces may be deleted, but the number of spaces
3111 deleted from each line will be the same (so that you can have
3112 indenting work correctly, for example).
3116 Those containing a single space followed by a single full stop
3117 character. These are rendered as blank lines. This is the
3118 <em>only</em> way to get a blank line<footnote>
3119 Completely empty lines will not be rendered as blank lines.
3120 Instead, they will cause the parser to think you're starting
3121 a whole new record in the control file, and will therefore
3122 likely abort with an error.
3127 Those containing a space, a full stop and some more characters.
3128 These are for future expansion. Do not use them.
3134 Do not use tab characters. Their effect is not predictable.
3138 See <ref id="descriptions"> for further information on this.
3142 In a <file>.changes</file> file, the <tt>Description</tt>
3143 field contains a summary of the descriptions for the packages
3144 being uploaded. For this case, the first line of the field
3145 value (the part on the same line as <tt>Description:</tt>) is
3146 always empty. The content of the field is expressed as
3147 continuation lines, one line per package. Each line is
3148 indented by one space and contains the name of a binary
3149 package, a space, a hyphen (<tt>-</tt>), a space, and the
3150 short description line from that package.
3154 <sect1 id="f-Distribution">
3155 <heading><tt>Distribution</tt></heading>
3158 In a <file>.changes</file> file or parsed changelog output
3159 this contains the (space-separated) name(s) of the
3160 distribution(s) where this version of the package should
3161 be installed. Valid distributions are determined by the
3162 archive maintainers.<footnote>
3163 Example distribution names in the Debian archive used in
3164 <file>.changes</file> files are:
3165 <taglist compact="compact">
3166 <tag><em>unstable</em></tag>
3168 This distribution value refers to the
3169 <em>developmental</em> part of the Debian distribution
3170 tree. Most new packages, new upstream versions of
3171 packages and bug fixes go into the <em>unstable</em>
3175 <tag><em>experimental</em></tag>
3177 The packages with this distribution value are deemed
3178 by their maintainers to be high risk. Oftentimes they
3179 represent early beta or developmental packages from
3180 various sources that the maintainers want people to
3181 try, but are not ready to be a part of the other parts
3182 of the Debian distribution tree.
3187 Others are used for updating stable releases or for
3188 security uploads. More information is available in the
3189 Debian Developer's Reference, section "The Debian
3193 The Debian archive software only supports listing a single
3194 distribution. Migration of packages to other distributions is
3195 handled outside of the upload process.
3200 <heading><tt>Date</tt></heading>
3203 This field includes the date the package was built or last edited.
3207 The value of this field is usually extracted from the
3208 <file>debian/changelog</file> file - see
3209 <ref id="dpkgchangelog">).
3213 <sect1 id="f-Format">
3214 <heading><tt>Format</tt></heading>
3217 This field specifies a format revision for the file.
3218 The most current format described in the Policy Manual
3219 is version <strong>1.5</strong>. The syntax of the
3220 format value is the same as that of a package version
3221 number except that no epoch or Debian revision is allowed
3222 - see <ref id="f-Version">.
3226 <sect1 id="f-Urgency">
3227 <heading><tt>Urgency</tt></heading>
3230 This is a description of how important it is to upgrade to
3231 this version from previous ones. It consists of a single
3232 keyword taking one of the values <tt>low</tt>,
3233 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3234 <tt>critical</tt><footnote>
3235 Other urgency values are supported with configuration
3236 changes in the archive software but are not used in Debian.
3237 The urgency affects how quickly a package will be considered
3238 for inclusion into the <tt>testing</tt> distribution and
3239 gives an indication of the importance of any fixes included
3240 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3241 treated as synonymous.
3242 </footnote> (not case-sensitive) followed by an optional
3243 commentary (separated by a space) which is usually in
3244 parentheses. For example:
3247 Urgency: low (HIGH for users of diversions)
3253 The value of this field is usually extracted from the
3254 <file>debian/changelog</file> file - see
3255 <ref id="dpkgchangelog">.
3259 <sect1 id="f-Changes">
3260 <heading><tt>Changes</tt></heading>
3263 This field contains the human-readable changes data, describing
3264 the differences between the last version and the current one.
3268 The first line of the field value (the part on the same line
3269 as <tt>Changes:</tt>) is always empty. The content of the
3270 field is expressed as continuation lines, with each line
3271 indented by at least one space. Blank lines must be
3272 represented by a line consisting only of a space and a full
3277 The value of this field is usually extracted from the
3278 <file>debian/changelog</file> file - see
3279 <ref id="dpkgchangelog">).
3283 Each version's change information should be preceded by a
3284 "title" line giving at least the version, distribution(s)
3285 and urgency, in a human-readable way.
3289 If data from several versions is being returned the entry
3290 for the most recent version should be returned first, and
3291 entries should be separated by the representation of a
3292 blank line (the "title" line may also be followed by the
3293 representation of a blank line).
3297 <sect1 id="f-Binary">
3298 <heading><tt>Binary</tt></heading>
3301 This field is a list of binary packages. Its syntax and
3302 meaning varies depending on the control file in which it
3307 When it appears in the <file>.dsc</file> file, it lists binary
3308 packages which a source package can produce, separated by
3310 A space after each comma is conventional.
3311 </footnote>. It may span multiple lines. The source package
3312 does not necessarily produce all of these binary packages for
3313 every architecture. The source control file doesn't contain
3314 details of which architectures are appropriate for which of
3315 the binary packages.
3319 When it appears in a <file>.changes</file> file, it lists the
3320 names of the binary packages being uploaded, separated by
3321 whitespace (not commas). It may span multiple lines.
3325 <sect1 id="f-Installed-Size">
3326 <heading><tt>Installed-Size</tt></heading>
3329 This field appears in the control files of binary packages,
3330 and in the <file>Packages</file> files. It gives an estimate
3331 of the total amount of disk space required to install the
3332 named package. Actual installed size may vary based on block
3333 size, file system properties, or actions taken by package
3338 The disk space is given as the integer value of the estimated
3339 installed size in bytes, divided by 1024 and rounded up.
3343 <sect1 id="f-Files">
3344 <heading><tt>Files</tt></heading>
3347 This field contains a list of files with information about
3348 each one. The exact information and syntax varies with
3353 In all cases, Files is a multiline field. The first line of
3354 the field value (the part on the same line as <tt>Files:</tt>)
3355 is always empty. The content of the field is expressed as
3356 continuation lines, one line per file. Each line must be
3357 indented by one space and contain a number of sub-fields,
3358 separated by spaces, as described below.
3362 In the <file>.dsc</file> file, each line contains the MD5
3363 checksum, size and filename of the tar file and (if
3364 applicable) diff file which make up the remainder of the
3365 source package<footnote>
3366 That is, the parts which are not the <tt>.dsc</tt>.
3367 </footnote>. For example:
3370 c6f698f19f2a2aa07dbb9bbda90a2754 571925 example_1.2.orig.tar.gz
3371 938512f08422f3509ff36f125f5873ba 6220 example_1.2-1.diff.gz
3373 The exact forms of the filenames are described
3374 in <ref id="pkg-sourcearchives">.
3378 In the <file>.changes</file> file this contains one line per
3379 file being uploaded. Each line contains the MD5 checksum,
3380 size, section and priority and the filename. For example:
3383 4c31ab7bfc40d3cf49d7811987390357 1428 text extra example_1.2-1.dsc
3384 c6f698f19f2a2aa07dbb9bbda90a2754 571925 text extra example_1.2.orig.tar.gz
3385 938512f08422f3509ff36f125f5873ba 6220 text extra example_1.2-1.diff.gz
3386 7c98fe853b3bbb47a00e5cd129b6cb56 703542 text extra example_1.2-1_i386.deb
3388 The <qref id="f-Section">section</qref>
3389 and <qref id="f-Priority">priority</qref> are the values of
3390 the corresponding fields in the main source control file. If
3391 no section or priority is specified then <tt>-</tt> should be
3392 used, though section and priority values must be specified for
3393 new packages to be installed properly.
3397 The special value <tt>byhand</tt> for the section in a
3398 <tt>.changes</tt> file indicates that the file in question
3399 is not an ordinary package file and must by installed by
3400 hand by the distribution maintainers. If the section is
3401 <tt>byhand</tt> the priority should be <tt>-</tt>.
3405 If a new Debian revision of a package is being shipped and
3406 no new original source archive is being distributed the
3407 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3408 entry for the original source archive
3409 <file><var>package</var>_<var>upstream-version</var>.orig.tar.gz</file>,
3410 but the <file>.changes</file> file should leave it out. In
3411 this case the original source archive on the distribution
3412 site must match exactly, byte-for-byte, the original
3413 source archive which was used to generate the
3414 <file>.dsc</file> file and diff which are being uploaded.</p>
3417 <sect1 id="f-Closes">
3418 <heading><tt>Closes</tt></heading>
3421 A space-separated list of bug report numbers that the upload
3422 governed by the .changes file closes.
3426 <sect1 id="f-Homepage">
3427 <heading><tt>Homepage</tt></heading>
3430 The URL of the web site for this package, preferably (when
3431 applicable) the site from which the original source can be
3432 obtained and any additional upstream documentation or
3433 information may be found. The content of this field is a
3434 simple URL without any surrounding characters such as
3442 <heading>User-defined fields</heading>
3445 Additional user-defined fields may be added to the
3446 source package control file. Such fields will be
3447 ignored, and not copied to (for example) binary or
3448 source package control files or upload control files.
3452 If you wish to add additional unsupported fields to
3453 these output files you should use the mechanism
3458 Fields in the main source control information file with
3459 names starting <tt>X</tt>, followed by one or more of
3460 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3461 be copied to the output files. Only the part of the
3462 field name after the hyphen will be used in the output
3463 file. Where the letter <tt>B</tt> is used the field
3464 will appear in binary package control files, where the
3465 letter <tt>S</tt> is used in source package control
3466 files and where <tt>C</tt> is used in upload control
3467 (<tt>.changes</tt>) files.
3471 For example, if the main source information control file
3474 XBS-Comment: I stand between the candle and the star.
3476 then the binary and source package control files will contain the
3479 Comment: I stand between the candle and the star.
3488 <chapt id="maintainerscripts">
3489 <heading>Package maintainer scripts and installation procedure</heading>
3492 <heading>Introduction to package maintainer scripts</heading>
3495 It is possible to supply scripts as part of a package which
3496 the package management system will run for you when your
3497 package is installed, upgraded or removed.
3501 These scripts are the files <prgn>preinst</prgn>,
3502 <prgn>postinst</prgn>, <prgn>prerm</prgn> and
3503 <prgn>postrm</prgn> in the control area of the package.
3504 They must be proper executable files; if they are scripts
3505 (which is recommended), they must start with the usual
3506 <tt>#!</tt> convention. They should be readable and
3507 executable by anyone, and must not be world-writable.
3511 The package management system looks at the exit status from
3512 these scripts. It is important that they exit with a
3513 non-zero status if there is an error, so that the package
3514 management system can stop its processing. For shell
3515 scripts this means that you <em>almost always</em> need to
3516 use <tt>set -e</tt> (this is usually true when writing shell
3517 scripts, in fact). It is also important, of course, that
3518 they exit with a zero status if everything went well.
3522 Additionally, packages interacting with users using
3523 <tt>debconf</tt> in the <prgn>postinst</prgn> script should
3524 install a <prgn>config</prgn> script in the control area,
3525 see <ref id="maintscriptprompt"> for details.
3529 When a package is upgraded a combination of the scripts from
3530 the old and new packages is called during the upgrade
3531 procedure. If your scripts are going to be at all
3532 complicated you need to be aware of this, and may need to
3533 check the arguments to your scripts.
3537 Broadly speaking the <prgn>preinst</prgn> is called before
3538 (a particular version of) a package is installed, and the
3539 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3540 before (a version of) a package is removed and the
3541 <prgn>postrm</prgn> afterwards.
3545 Programs called from maintainer scripts should not normally
3546 have a path prepended to them. Before installation is
3547 started, the package management system checks to see if the
3548 programs <prgn>ldconfig</prgn>,
3549 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3550 and <prgn>update-rc.d</prgn> can be found via the
3551 <tt>PATH</tt> environment variable. Those programs, and any
3552 other program that one would expect to be in the
3553 <tt>PATH</tt>, should thus be invoked without an absolute
3554 pathname. Maintainer scripts should also not reset the
3555 <tt>PATH</tt>, though they might choose to modify it by
3556 prepending or appending package-specific directories. These
3557 considerations really apply to all shell scripts.</p>
3560 <sect id="idempotency">
3561 <heading>Maintainer scripts idempotency</heading>
3564 It is necessary for the error recovery procedures that the
3565 scripts be idempotent. This means that if it is run
3566 successfully, and then it is called again, it doesn't bomb
3567 out or cause any harm, but just ensures that everything is
3568 the way it ought to be. If the first call failed, or
3569 aborted half way through for some reason, the second call
3570 should merely do the things that were left undone the first
3571 time, if any, and exit with a success status if everything
3573 This is so that if an error occurs, the user interrupts
3574 <prgn>dpkg</prgn> or some other unforeseen circumstance
3575 happens you don't leave the user with a badly-broken
3576 package when <prgn>dpkg</prgn> attempts to repeat the
3582 <sect id="controllingterminal">
3583 <heading>Controlling terminal for maintainer scripts</heading>
3586 The maintainer scripts are guaranteed to run with a
3587 controlling terminal and can interact with the user.
3588 Because these scripts may be executed with standard output
3589 redirected into a pipe for logging purposes, Perl scripts
3590 should set unbuffered output by setting <tt>$|=1</tt> so
3591 that the output is printed immediately rather than being
3595 <sect id="exitstatus">
3596 <heading>Exit status</heading>
3599 Each script must return a zero exit status for
3600 success, or a nonzero one for failure, since the package
3601 management system looks for the exit status of these scripts
3602 and determines what action to take next based on that datum.
3606 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3611 <list compact="compact">
3613 <var>new-preinst</var> <tt>install</tt>
3616 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3619 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3622 <var>old-preinst</var> <tt>abort-upgrade</tt>
3623 <var>new-version</var>
3628 <list compact="compact">
3630 <var>postinst</var> <tt>configure</tt>
3631 <var>most-recently-configured-version</var>
3634 <var>old-postinst</var> <tt>abort-upgrade</tt>
3635 <var>new-version</var>
3638 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3639 <tt>in-favour</tt> <var>package</var>
3640 <var>new-version</var>
3643 <var>postinst</var> <tt>abort-remove</tt>
3646 <var>deconfigured's-postinst</var>
3647 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3648 <var>failed-install-package</var> <var>version</var>
3649 [<tt>removing</tt> <var>conflicting-package</var>
3655 <list compact="compact">
3657 <var>prerm</var> <tt>remove</tt>
3660 <var>old-prerm</var> <tt>upgrade</tt>
3661 <var>new-version</var>
3664 <var>new-prerm</var> <tt>failed-upgrade</tt>
3665 <var>old-version</var>
3668 <var>conflictor's-prerm</var> <tt>remove</tt>
3669 <tt>in-favour</tt> <var>package</var>
3670 <var>new-version</var>
3673 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3674 <tt>in-favour</tt> <var>package-being-installed</var>
3675 <var>version</var> [<tt>removing</tt>
3676 <var>conflicting-package</var>
3682 <list compact="compact">
3684 <var>postrm</var> <tt>remove</tt>
3687 <var>postrm</var> <tt>purge</tt>
3690 <var>old-postrm</var> <tt>upgrade</tt>
3691 <var>new-version</var>
3694 <var>new-postrm</var> <tt>failed-upgrade</tt>
3695 <var>old-version</var>
3698 <var>new-postrm</var> <tt>abort-install</tt>
3701 <var>new-postrm</var> <tt>abort-install</tt>
3702 <var>old-version</var>
3705 <var>new-postrm</var> <tt>abort-upgrade</tt>
3706 <var>old-version</var>
3709 <var>disappearer's-postrm</var> <tt>disappear</tt>
3710 <var>overwriter</var>
3711 <var>overwriter-version</var>
3717 <sect id="unpackphase">
3718 <heading>Details of unpack phase of installation or upgrade</heading>
3721 The procedure on installation/upgrade/overwrite/disappear
3722 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3723 stage of <tt>dpkg --install</tt>) is as follows. In each
3724 case, if a major error occurs (unless listed below) the
3725 actions are, in general, run backwards - this means that the
3726 maintainer scripts are run with different arguments in
3727 reverse order. These are the "error unwind" calls listed
3734 If a version of the package is already installed, call
3735 <example compact="compact">
3736 <var>old-prerm</var> upgrade <var>new-version</var>
3740 If the script runs but exits with a non-zero
3741 exit status, <prgn>dpkg</prgn> will attempt:
3742 <example compact="compact">
3743 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3745 If this works, the upgrade continues. If this
3746 does not work, the error unwind:
3747 <example compact="compact">
3748 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3750 If this works, then the old-version is
3751 "Installed", if not, the old version is in a
3752 "Half-Configured" state.
3758 If a "conflicting" package is being removed at the same time,
3759 or if any package will be broken (due to <tt>Breaks</tt>):
3762 If <tt>--auto-deconfigure</tt> is
3763 specified, call, for each package to be deconfigured
3764 due to <tt>Breaks</tt>:
3765 <example compact="compact">
3766 <var>deconfigured's-prerm</var> deconfigure \
3767 in-favour <var>package-being-installed</var> <var>version</var>
3770 <example compact="compact">
3771 <var>deconfigured's-postinst</var> abort-deconfigure \
3772 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3774 The deconfigured packages are marked as
3775 requiring configuration, so that if
3776 <tt>--install</tt> is used they will be
3777 configured again if possible.
3780 If any packages depended on a conflicting
3781 package being removed and <tt>--auto-deconfigure</tt> is
3782 specified, call, for each such package:
3783 <example compact="compact">
3784 <var>deconfigured's-prerm</var> deconfigure \
3785 in-favour <var>package-being-installed</var> <var>version</var> \
3786 removing <var>conflicting-package</var> <var>version</var>
3789 <example compact="compact">
3790 <var>deconfigured's-postinst</var> abort-deconfigure \
3791 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3792 removing <var>conflicting-package</var> <var>version</var>
3794 The deconfigured packages are marked as
3795 requiring configuration, so that if
3796 <tt>--install</tt> is used they will be
3797 configured again if possible.
3800 To prepare for removal of each conflicting package, call:
3801 <example compact="compact">
3802 <var>conflictor's-prerm</var> remove \
3803 in-favour <var>package</var> <var>new-version</var>
3806 <example compact="compact">
3807 <var>conflictor's-postinst</var> abort-remove \
3808 in-favour <var>package</var> <var>new-version</var>
3817 If the package is being upgraded, call:
3818 <example compact="compact">
3819 <var>new-preinst</var> upgrade <var>old-version</var>
3821 If this fails, we call:
3823 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3830 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3832 is called. If this works, then the old version
3833 is in an "Installed" state, or else it is left
3834 in an "Unpacked" state.
3839 If it fails, then the old version is left
3840 in an "Half-Installed" state.
3847 Otherwise, if the package had some configuration
3848 files from a previous version installed (i.e., it
3849 is in the "configuration files only" state):
3850 <example compact="compact">
3851 <var>new-preinst</var> install <var>old-version</var>
3855 <var>new-postrm</var> abort-install <var>old-version</var>
3857 If this fails, the package is left in a
3858 "Half-Installed" state, which requires a
3859 reinstall. If it works, the packages is left in
3860 a "Config-Files" state.
3863 Otherwise (i.e., the package was completely purged):
3864 <example compact="compact">
3865 <var>new-preinst</var> install
3868 <example compact="compact">
3869 <var>new-postrm</var> abort-install
3871 If the error-unwind fails, the package is in a
3872 "Half-Installed" phase, and requires a
3873 reinstall. If the error unwind works, the
3874 package is in a not installed state.
3881 The new package's files are unpacked, overwriting any
3882 that may be on the system already, for example any
3883 from the old version of the same package or from
3884 another package. Backups of the old files are kept
3885 temporarily, and if anything goes wrong the package
3886 management system will attempt to put them back as
3887 part of the error unwind.
3891 It is an error for a package to contain files which
3892 are on the system in another package, unless
3893 <tt>Replaces</tt> is used (see <ref id="replaces">).
3895 The following paragraph is not currently the case:
3896 Currently the <tt>- - force-overwrite</tt> flag is
3897 enabled, downgrading it to a warning, but this may not
3903 It is a more serious error for a package to contain a
3904 plain file or other kind of non-directory where another
3905 package has a directory (again, unless
3906 <tt>Replaces</tt> is used). This error can be
3907 overridden if desired using
3908 <tt>--force-overwrite-dir</tt>, but this is not
3913 Packages which overwrite each other's files produce
3914 behavior which, though deterministic, is hard for the
3915 system administrator to understand. It can easily
3916 lead to "missing" programs if, for example, a package
3917 is installed which overwrites a file from another
3918 package, and is then removed again.<footnote>
3919 Part of the problem is due to what is arguably a
3920 bug in <prgn>dpkg</prgn>.
3925 A directory will never be replaced by a symbolic link
3926 to a directory or vice versa; instead, the existing
3927 state (symlink or not) will be left alone and
3928 <prgn>dpkg</prgn> will follow the symlink if there is
3937 If the package is being upgraded, call
3938 <example compact="compact">
3939 <var>old-postrm</var> upgrade <var>new-version</var>
3943 If this fails, <prgn>dpkg</prgn> will attempt:
3944 <example compact="compact">
3945 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3947 If this works, installation continues. If not,
3949 <example compact="compact">
3950 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3952 If this fails, the old version is left in a
3953 "Half-Installed" state. If it works, dpkg now
3955 <example compact="compact">
3956 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3958 If this fails, the old version is left in a
3959 "Half-Installed" state. If it works, dpkg now
3961 <example compact="compact">
3962 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3964 If this fails, the old version is in an
3971 This is the point of no return - if
3972 <prgn>dpkg</prgn> gets this far, it won't back off
3973 past this point if an error occurs. This will
3974 leave the package in a fairly bad state, which
3975 will require a successful re-installation to clear
3976 up, but it's when <prgn>dpkg</prgn> starts doing
3977 things that are irreversible.
3982 Any files which were in the old version of the package
3983 but not in the new are removed.
3987 The new file list replaces the old.
3991 The new maintainer scripts replace the old.
3995 Any packages all of whose files have been overwritten
3996 during the installation, and which aren't required for
3997 dependencies, are considered to have been removed.
3998 For each such package
4001 <prgn>dpkg</prgn> calls:
4002 <example compact="compact">
4003 <var>disappearer's-postrm</var> disappear \
4004 <var>overwriter</var> <var>overwriter-version</var>
4008 The package's maintainer scripts are removed.
4011 It is noted in the status database as being in a
4012 sane state, namely not installed (any conffiles
4013 it may have are ignored, rather than being
4014 removed by <prgn>dpkg</prgn>). Note that
4015 disappearing packages do not have their prerm
4016 called, because <prgn>dpkg</prgn> doesn't know
4017 in advance that the package is going to
4024 Any files in the package we're unpacking that are also
4025 listed in the file lists of other packages are removed
4026 from those lists. (This will lobotomize the file list
4027 of the "conflicting" package if there is one.)
4031 The backup files made during installation, above, are
4037 The new package's status is now sane, and recorded as
4042 Here is another point of no return - if the
4043 conflicting package's removal fails we do not unwind
4044 the rest of the installation; the conflicting package
4045 is left in a half-removed limbo.
4050 If there was a conflicting package we go and do the
4051 removal actions (described below), starting with the
4052 removal of the conflicting package's files (any that
4053 are also in the package being installed have already
4054 been removed from the conflicting package's file list,
4055 and so do not get removed now).
4061 <sect id="configdetails"><heading>Details of configuration</heading>
4064 When we configure a package (this happens with <tt>dpkg
4065 --install</tt> and <tt>dpkg --configure</tt>), we first
4066 update any <tt>conffile</tt>s and then call:
4067 <example compact="compact">
4068 <var>postinst</var> configure <var>most-recently-configured-version</var>
4073 No attempt is made to unwind after errors during
4074 configuration. If the configuration fails, the package is in
4075 a "Failed Config" state, and an error message is generated.
4079 If there is no most recently configured version
4080 <prgn>dpkg</prgn> will pass a null argument.
4083 Historical note: Truly ancient (pre-1997) versions of
4084 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4085 (including the angle brackets) in this case. Even older
4086 ones did not pass a second argument at all, under any
4087 circumstance. Note that upgrades using such an old dpkg
4088 version are unlikely to work for other reasons, even if
4089 this old argument behavior is handled by your postinst script.
4095 <sect id="removedetails"><heading>Details of removal and/or
4096 configuration purging</heading>
4102 <example compact="compact">
4103 <var>prerm</var> remove
4107 If prerm fails during replacement due to conflict
4109 <var>conflictor's-postinst</var> abort-remove \
4110 in-favour <var>package</var> <var>new-version</var>
4114 <var>postinst</var> abort-remove
4118 If this fails, the package is in a "Half-Configured"
4119 state, or else it remains "Installed".
4123 The package's files are removed (except <tt>conffile</tt>s).
4126 <example compact="compact">
4127 <var>postrm</var> remove
4131 If it fails, there's no error unwind, and the package is in
4132 an "Half-Installed" state.
4137 All the maintainer scripts except the <prgn>postrm</prgn>
4142 If we aren't purging the package we stop here. Note
4143 that packages which have no <prgn>postrm</prgn> and no
4144 <tt>conffile</tt>s are automatically purged when
4145 removed, as there is no difference except for the
4146 <prgn>dpkg</prgn> status.
4150 The <tt>conffile</tt>s and any backup files
4151 (<tt>~</tt>-files, <tt>#*#</tt> files,
4152 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4157 <example compact="compact">
4158 <var>postrm</var> purge
4162 If this fails, the package remains in a "Config-Files"
4167 The package's file list is removed.
4176 <chapt id="relationships">
4177 <heading>Declaring relationships between packages</heading>
4179 <sect id="depsyntax">
4180 <heading>Syntax of relationship fields</heading>
4183 These fields all have a uniform syntax. They are a list of
4184 package names separated by commas.
4188 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4189 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4190 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4191 control file fields of the package, which declare
4192 dependencies on other packages, the package names listed may
4193 also include lists of alternative package names, separated
4194 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4195 if any one of the alternative packages is installed, that
4196 part of the dependency is considered to be satisfied.
4200 All of the fields except for <tt>Provides</tt> may restrict
4201 their applicability to particular versions of each named
4202 package. This is done in parentheses after each individual
4203 package name; the parentheses should contain a relation from
4204 the list below followed by a version number, in the format
4205 described in <ref id="f-Version">.
4209 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4210 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4211 strictly earlier, earlier or equal, exactly equal, later or
4212 equal and strictly later, respectively. The deprecated
4213 forms <tt><</tt> and <tt>></tt> were used to mean
4214 earlier/later or equal, rather than strictly earlier/later,
4215 so they should not appear in new packages (though
4216 <prgn>dpkg</prgn> still supports them).
4220 Whitespace may appear at any point in the version
4221 specification subject to the rules in <ref
4222 id="controlsyntax">, and must appear where it's necessary to
4223 disambiguate; it is not otherwise significant. All of the
4224 relationship fields may span multiple lines. For
4225 consistency and in case of future changes to
4226 <prgn>dpkg</prgn> it is recommended that a single space be
4227 used after a version relationship and before a version
4228 number; it is also conventional to put a single space after
4229 each comma, on either side of each vertical bar, and before
4230 each open parenthesis. When wrapping a relationship field, it
4231 is conventional to do so after a comma and before the space
4232 following that comma.
4236 For example, a list of dependencies might appear as:
4237 <example compact="compact">
4240 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4245 All fields that specify build-time relationships
4246 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4247 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
4248 may be restricted to a certain set of architectures. This
4249 is indicated in brackets after each individual package name and
4250 the optional version specification. The brackets enclose a
4251 list of Debian architecture names separated by whitespace.
4252 Exclamation marks may be prepended to each of the names.
4253 (It is not permitted for some names to be prepended with
4254 exclamation marks while others aren't.) If the current Debian
4255 host architecture is not in this list and there are no
4256 exclamation marks in the list, or it is in the list with a
4257 prepended exclamation mark, the package name and the
4258 associated version specification are ignored completely for
4259 the purposes of defining the relationships.
4264 <example compact="compact">
4266 Build-Depends-Indep: texinfo
4267 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4268 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4270 requires <tt>kernel-headers-2.2.10</tt> on all architectures
4271 other than hurd-i386 and requires <tt>hurd-dev</tt> and
4272 <tt>gnumach-dev</tt> only on hurd-i386.
4276 If the architecture-restricted dependency is part of a set of
4277 alternatives using <tt>|</tt>, that alternative is ignored
4278 completely on architectures that do not match the restriction.
4280 <example compact="compact">
4281 Build-Depends: foo [!i386] | bar [!amd64]
4283 is equivalent to <tt>bar</tt> on the i386 architecture, to
4284 <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
4285 bar</tt> on all other architectures.
4289 All fields that specify build-time relationships may also be
4290 restricted to a certain set of architectures using architecture
4291 wildcards. The syntax for declaring such restrictions is the
4292 same as declaring restrictions using a certain set of
4293 architectures without architecture wildcards. For example:
4294 <example compact="compact">
4295 Build-Depends: foo [linux-any], bar [any-i386], baz [!linux-any]
4297 is equivalent to <tt>foo</tt> on architectures using the Linux
4298 kernel and any cpu, <tt>bar</tt> on architectures using any
4299 kernel and an i386 cpu, and <tt>baz</tt> on any architecture
4300 using a kernel other than Linux.
4304 Note that the binary package relationship fields such as
4305 <tt>Depends</tt> appear in one of the binary package
4306 sections of the control file, whereas the build-time
4307 relationships such as <tt>Build-Depends</tt> appear in the
4308 source package section of the control file (which is the
4313 <sect id="binarydeps">
4314 <heading>Binary Dependencies - <tt>Depends</tt>,
4315 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4316 <tt>Pre-Depends</tt>
4320 Packages can declare in their control file that they have
4321 certain relationships to other packages - for example, that
4322 they may not be installed at the same time as certain other
4323 packages, and/or that they depend on the presence of others.
4327 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4328 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4329 <tt>Breaks</tt> and <tt>Conflicts</tt> control file fields.
4330 <tt>Breaks</tt> is described in <ref id="breaks">, and
4331 <tt>Conflicts</tt> is described in <ref id="conflicts">. The
4332 rest are described below.
4336 These seven fields are used to declare a dependency
4337 relationship by one package on another. Except for
4338 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4339 depending (binary) package's control file.
4340 (<tt>Enhances</tt> appears in the recommending package's
4341 control file, and <tt>Breaks</tt> appears in the version of
4342 depended-on package which causes the named package to
4347 A <tt>Depends</tt> field takes effect <em>only</em> when a
4348 package is to be configured. It does not prevent a package
4349 being on the system in an unconfigured state while its
4350 dependencies are unsatisfied, and it is possible to replace
4351 a package whose dependencies are satisfied and which is
4352 properly installed with a different version whose
4353 dependencies are not and cannot be satisfied; when this is
4354 done the depending package will be left unconfigured (since
4355 attempts to configure it will give errors) and will not
4356 function properly. If it is necessary, a
4357 <tt>Pre-Depends</tt> field can be used, which has a partial
4358 effect even when a package is being unpacked, as explained
4359 in detail below. (The other three dependency fields,
4360 <tt>Recommends</tt>, <tt>Suggests</tt> and
4361 <tt>Enhances</tt>, are only used by the various front-ends
4362 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4363 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4367 For this reason packages in an installation run are usually
4368 all unpacked first and all configured later; this gives
4369 later versions of packages with dependencies on later
4370 versions of other packages the opportunity to have their
4371 dependencies satisfied.
4375 In case of circular dependencies, since installation or
4376 removal order honoring the dependency order can't be
4377 established, dependency loops are broken at some point
4378 (based on rules below), and some packages may not be able to
4379 rely on their dependencies being present when being
4380 installed or removed, depending on which side of the break
4381 of the circular dependency loop they happen to be on. If one
4382 of the packages in the loop has no postinst script, then the
4383 cycle will be broken at that package, so as to ensure that
4384 all postinst scripts run with the dependencies properly
4385 configured if this is possible. Otherwise the breaking point
4390 The <tt>Depends</tt> field thus allows package maintainers
4391 to impose an order in which packages should be configured.
4395 The meaning of the five dependency fields is as follows:
4397 <tag><tt>Depends</tt></tag>
4400 This declares an absolute dependency. A package will
4401 not be configured unless all of the packages listed in
4402 its <tt>Depends</tt> field have been correctly
4407 The <tt>Depends</tt> field should be used if the
4408 depended-on package is required for the depending
4409 package to provide a significant amount of
4414 The <tt>Depends</tt> field should also be used if the
4415 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4416 <prgn>postrm</prgn> scripts require the package to be
4417 present in order to run. Note, however, that the
4418 <prgn>postrm</prgn> cannot rely on any non-essential
4419 packages to be present during the <tt>purge</tt>
4423 <tag><tt>Recommends</tt></tag>
4426 This declares a strong, but not absolute, dependency.
4430 The <tt>Recommends</tt> field should list packages
4431 that would be found together with this one in all but
4432 unusual installations.
4436 <tag><tt>Suggests</tt></tag>
4438 This is used to declare that one package may be more
4439 useful with one or more others. Using this field
4440 tells the packaging system and the user that the
4441 listed packages are related to this one and can
4442 perhaps enhance its usefulness, but that installing
4443 this one without them is perfectly reasonable.
4446 <tag><tt>Enhances</tt></tag>
4448 This field is similar to Suggests but works in the
4449 opposite direction. It is used to declare that a
4450 package can enhance the functionality of another
4454 <tag><tt>Pre-Depends</tt></tag>
4457 This field is like <tt>Depends</tt>, except that it
4458 also forces <prgn>dpkg</prgn> to complete installation
4459 of the packages named before even starting the
4460 installation of the package which declares the
4461 pre-dependency, as follows:
4465 When a package declaring a pre-dependency is about to
4466 be <em>unpacked</em> the pre-dependency can be
4467 satisfied if the depended-on package is either fully
4468 configured, <em>or even if</em> the depended-on
4469 package(s) are only unpacked or in the "Half-Configured"
4470 state, provided that they have been configured
4471 correctly at some point in the past (and not removed
4472 or partially removed since). In this case, both the
4473 previously-configured and currently unpacked or
4474 "Half-Configured" versions must satisfy any version
4475 clause in the <tt>Pre-Depends</tt> field.
4479 When the package declaring a pre-dependency is about
4480 to be <em>configured</em>, the pre-dependency will be
4481 treated as a normal <tt>Depends</tt>, that is, it will
4482 be considered satisfied only if the depended-on
4483 package has been correctly configured.
4487 <tt>Pre-Depends</tt> should be used sparingly,
4488 preferably only by packages whose premature upgrade or
4489 installation would hamper the ability of the system to
4490 continue with any upgrade that might be in progress.
4494 <tt>Pre-Depends</tt> are also required if the
4495 <prgn>preinst</prgn> script depends on the named
4496 package. It is best to avoid this situation if
4504 When selecting which level of dependency to use you should
4505 consider how important the depended-on package is to the
4506 functionality of the one declaring the dependency. Some
4507 packages are composed of components of varying degrees of
4508 importance. Such a package should list using
4509 <tt>Depends</tt> the package(s) which are required by the
4510 more important components. The other components'
4511 requirements may be mentioned as Suggestions or
4512 Recommendations, as appropriate to the components' relative
4518 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4521 When one binary package declares that it breaks another,
4522 <prgn>dpkg</prgn> will refuse to allow the package which
4523 declares <tt>Breaks</tt> be installed unless the broken
4524 package is deconfigured first, and it will refuse to
4525 allow the broken package to be reconfigured.
4529 A package will not be regarded as causing breakage merely
4530 because its configuration files are still installed; it must
4531 be at least "Half-Installed".
4535 A special exception is made for packages which declare that
4536 they break their own package name or a virtual package which
4537 they provide (see below): this does not count as a real
4542 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4543 version clause; such a <tt>Breaks</tt> is introduced in the
4544 version of an (implicit or explicit) dependency which
4545 violates an assumption or reveals a bug in earlier versions
4546 of the broken package. This use of <tt>Breaks</tt> will
4547 inform higher-level package management tools that broken
4548 package must be upgraded before the new one.
4552 If the breaking package also overwrites some files from the
4553 older package, it should use <tt>Replaces</tt> (not
4554 <tt>Conflicts</tt>) to ensure this goes smoothly.
4558 <sect id="conflicts">
4559 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4562 When one binary package declares a conflict with another
4563 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4564 refuse to allow them to be installed on the system at the
4569 If one package is to be installed, the other must be removed
4570 first - if the package being installed is marked as
4571 replacing (see <ref id="replaces">) the one on the system,
4572 or the one on the system is marked as deselected, or both
4573 packages are marked <tt>Essential</tt>, then
4574 <prgn>dpkg</prgn> will automatically remove the package
4575 which is causing the conflict, otherwise it will halt the
4576 installation of the new package with an error. This
4577 mechanism is specifically designed to produce an error when
4578 the installed package is <tt>Essential</tt>, but the new
4583 A package will not cause a conflict merely because its
4584 configuration files are still installed; it must be at least
4589 A special exception is made for packages which declare a
4590 conflict with their own package name, or with a virtual
4591 package which they provide (see below): this does not
4592 prevent their installation, and allows a package to conflict
4593 with others providing a replacement for it. You use this
4594 feature when you want the package in question to be the only
4595 package providing some feature.
4599 A <tt>Conflicts</tt> entry should almost never have an
4600 "earlier than" version clause. This would prevent
4601 <prgn>dpkg</prgn> from upgrading or installing the package
4602 which declared such a conflict until the upgrade or removal
4603 of the conflicted-with package had been completed. Instead,
4604 <tt>Breaks</tt> may be used.
4608 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4612 As well as the names of actual ("concrete") packages, the
4613 package relationship fields <tt>Depends</tt>,
4614 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4615 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4616 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4617 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4618 may mention "virtual packages".
4622 A <em>virtual package</em> is one which appears in the
4623 <tt>Provides</tt> control file field of another package.
4624 The effect is as if the package(s) which provide a
4625 particular virtual package name had been listed by name
4626 everywhere the virtual package name appears. (See also <ref
4631 If there are both concrete and virtual packages of the same
4632 name, then the dependency may be satisfied (or the conflict
4633 caused) by either the concrete package with the name in
4634 question or any other concrete package which provides the
4635 virtual package with the name in question. This is so that,
4636 for example, supposing we have
4637 <example compact="compact">
4640 </example> and someone else releases an enhanced version of
4641 the <tt>bar</tt> package they can say:
4642 <example compact="compact">
4646 and the <tt>bar-plus</tt> package will now also satisfy the
4647 dependency for the <tt>foo</tt> package.
4651 If a relationship field has a version number attached
4652 then only real packages will be considered to see whether
4653 the relationship is satisfied (or the prohibition violated,
4654 for a conflict or breakage) - it is assumed that a real
4655 package which provides the virtual package is not of the
4656 "right" version. So, a <tt>Provides</tt> field may not
4657 contain version numbers, and the version number of the
4658 concrete package which provides a particular virtual package
4659 will not be looked at when considering a dependency on or
4660 conflict with the virtual package name.
4664 It is likely that the ability will be added in a future
4665 release of <prgn>dpkg</prgn> to specify a version number for
4666 each virtual package it provides. This feature is not yet
4667 present, however, and is expected to be used only
4672 If you want to specify which of a set of real packages
4673 should be the default to satisfy a particular dependency on
4674 a virtual package, you should list the real package as an
4675 alternative before the virtual one.
4680 <sect id="replaces"><heading>Overwriting files and replacing
4681 packages - <tt>Replaces</tt></heading>
4684 Packages can declare in their control file that they should
4685 overwrite files in certain other packages, or completely
4686 replace other packages. The <tt>Replaces</tt> control file
4687 field has these two distinct purposes.
4690 <sect1><heading>Overwriting files in other packages</heading>
4693 Firstly, as mentioned before, it is usually an error for a
4694 package to contain files which are on the system in
4699 However, if the overwriting package declares that it
4700 <tt>Replaces</tt> the one containing the file being
4701 overwritten, then <prgn>dpkg</prgn> will replace the file
4702 from the old package with that from the new. The file
4703 will no longer be listed as "owned" by the old package.
4707 If a package is completely replaced in this way, so that
4708 <prgn>dpkg</prgn> does not know of any files it still
4709 contains, it is considered to have "disappeared". It will
4710 be marked as not wanted on the system (selected for
4711 removal) and not installed. Any <tt>conffile</tt>s
4712 details noted for the package will be ignored, as they
4713 will have been taken over by the overwriting package. The
4714 package's <prgn>postrm</prgn> script will be run with a
4715 special argument to allow the package to do any final
4716 cleanup required. See <ref id="mscriptsinstact">.
4719 Replaces is a one way relationship -- you have to
4720 install the replacing package after the replaced
4727 For this usage of <tt>Replaces</tt>, virtual packages (see
4728 <ref id="virtual">) are not considered when looking at a
4729 <tt>Replaces</tt> field - the packages declared as being
4730 replaced must be mentioned by their real names.
4734 Furthermore, this usage of <tt>Replaces</tt> only takes
4735 effect when both packages are at least partially on the
4736 system at once, so that it can only happen if they do not
4737 conflict or if the conflict has been overridden.
4742 <sect1><heading>Replacing whole packages, forcing their
4746 Secondly, <tt>Replaces</tt> allows the packaging system to
4747 resolve which package should be removed when there is a
4748 conflict - see <ref id="conflicts">. This usage only
4749 takes effect when the two packages <em>do</em> conflict,
4750 so that the two usages of this field do not interfere with
4755 In this situation, the package declared as being replaced
4756 can be a virtual package, so for example, all mail
4757 transport agents (MTAs) would have the following fields in
4758 their control files:
4759 <example compact="compact">
4760 Provides: mail-transport-agent
4761 Conflicts: mail-transport-agent
4762 Replaces: mail-transport-agent
4764 ensuring that only one MTA can be installed at any one
4769 <sect id="sourcebinarydeps">
4770 <heading>Relationships between source and binary packages -
4771 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4772 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4776 Source packages that require certain binary packages to be
4777 installed or absent at the time of building the package
4778 can declare relationships to those binary packages.
4782 This is done using the <tt>Build-Depends</tt>,
4783 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4784 <tt>Build-Conflicts-Indep</tt> control file fields.
4788 Build-dependencies on "build-essential" binary packages can be
4789 omitted. Please see <ref id="pkg-relations"> for more information.
4793 The dependencies and conflicts they define must be satisfied
4794 (as defined earlier for binary packages) in order to invoke
4795 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4797 If you make "build-arch" or "binary-arch", you need
4798 Build-Depends. If you make "build-indep" or
4799 "binary-indep", you need Build-Depends and
4800 Build-Depends-Indep. If you make "build" or "binary",
4804 There is no Build-Depends-Arch; this role is essentially
4805 met with Build-Depends. Anyone building the
4806 <tt>build-indep</tt> and binary-indep<tt></tt> targets
4807 is basically assumed to be building the whole package
4808 anyway and so installs all build dependencies. The
4809 autobuilders use <tt>dpkg-buildpackage -B</tt>, which
4810 calls <tt>build</tt> (not <tt>build-arch</tt>, since it
4811 does not yet know how to check for its existence) and
4812 <tt>binary-arch</tt>.
4815 The purpose of the original split, I recall, was so that
4816 the autobuilders wouldn't need to install extra packages
4817 needed only for the binary-indep targets. But without a
4818 build-arch/build-indep split, this didn't work, since
4819 most of the work is done in the build target, not in the
4825 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4827 The <tt>Build-Depends</tt> and
4828 <tt>Build-Conflicts</tt> fields must be satisfied when
4829 any of the following targets is invoked:
4830 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4831 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4832 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4834 <tag><tt>Build-Depends-Indep</tt>,
4835 <tt>Build-Conflicts-Indep</tt></tag>
4837 The <tt>Build-Depends-Indep</tt> and
4838 <tt>Build-Conflicts-Indep</tt> fields must be
4839 satisfied when any of the following targets is
4840 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4841 <tt>binary</tt> and <tt>binary-indep</tt>.
4851 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4854 Packages containing shared libraries must be constructed with
4855 a little care to make sure that the shared library is always
4856 available. This is especially important for packages whose
4857 shared libraries are vitally important, such as the C library
4858 (currently <tt>libc6</tt>).
4862 Packages involving shared libraries should be split up into
4863 several binary packages. This section mostly deals with how
4864 this separation is to be accomplished; rules for files within
4865 the shared library packages are in <ref id="libraries"> instead.
4868 <sect id="sharedlibs-runtime">
4869 <heading>Run-time shared libraries</heading>
4872 The run-time shared library needs to be placed in a package
4873 whose name changes whenever the shared object version
4876 Since it is common place to install several versions of a
4877 package that just provides shared libraries, it is a
4878 good idea that the library package should not
4879 contain any extraneous non-versioned files, unless they
4880 happen to be in versioned directories.</p>
4882 The most common mechanism is to place it in a package
4884 <package><var>libraryname</var><var>soversion</var></package>,
4885 where <file><var>soversion</var></file> is the version number
4886 in the soname of the shared library<footnote>
4887 The soname is the shared object name: it's the thing
4888 that has to match exactly between building an executable
4889 and running it for the dynamic linker to be able run the
4890 program. For example, if the soname of the library is
4891 <file>libfoo.so.6</file>, the library package would be
4892 called <file>libfoo6</file>.
4894 Alternatively, if it would be confusing to directly append
4895 <var>soversion</var> to <var>libraryname</var> (e.g. because
4896 <var>libraryname</var> itself ends in a number), you may use
4897 <package><var>libraryname</var>-<var>soversion</var></package> and
4898 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4903 If you have several shared libraries built from the same
4904 source tree you may lump them all together into a single
4905 shared library package, provided that you change all of
4906 their sonames at once (so that you don't get filename
4907 clashes if you try to install different versions of the
4908 combined shared libraries package).
4912 The package should install the shared libraries under
4913 their normal names. For example, the <package>libgdbm3</package>
4914 package should install <file>libgdbm.so.3.0.0</file> as
4915 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4916 renamed or re-linked by any <prgn>prerm</prgn> or
4917 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4918 of renaming things safely without affecting running programs,
4919 and attempts to interfere with this are likely to lead to
4924 Shared libraries should not be installed executable, since
4925 the dynamic linker does not require this and trying to
4926 execute a shared library usually results in a core dump.
4930 The run-time library package should include the symbolic link that
4931 <prgn>ldconfig</prgn> would create for the shared libraries.
4932 For example, the <package>libgdbm3</package> package should include
4933 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4934 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4935 linker (for example <prgn>ld.so</prgn> or
4936 <prgn>ld-linux.so.*</prgn>) can find the library between the
4937 time that <prgn>dpkg</prgn> installs it and the time that
4938 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4940 The package management system requires the library to be
4941 placed before the symbolic link pointing to it in the
4942 <file>.deb</file> file. This is so that when
4943 <prgn>dpkg</prgn> comes to install the symlink
4944 (overwriting the previous symlink pointing at an older
4945 version of the library), the new shared library is already
4946 in place. In the past, this was achieved by creating the
4947 library in the temporary packaging directory before
4948 creating the symlink. Unfortunately, this was not always
4949 effective, since the building of the tar file in the
4950 <file>.deb</file> depended on the behavior of the underlying
4951 file system. Some file systems (such as reiserfs) reorder
4952 the files so that the order of creation is forgotten.
4953 Since version 1.7.0, <prgn>dpkg</prgn>
4954 reorders the files itself as necessary when building a
4955 package. Thus it is no longer important to concern
4956 oneself with the order of file creation.
4960 <sect1 id="ldconfig">
4961 <heading><tt>ldconfig</tt></heading>
4964 Any package installing shared libraries in one of the default
4965 library directories of the dynamic linker (which are currently
4966 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4967 listed in <file>/etc/ld.so.conf</file><footnote>
4969 <list compact="compact">
4970 <item>/usr/local/lib</item>
4971 <item>/usr/lib/libc5-compat</item>
4972 <item>/lib/libc5-compat</item>
4975 must use <prgn>ldconfig</prgn> to update the shared library
4980 The package maintainer scripts must only call
4981 <prgn>ldconfig</prgn> under these circumstances:
4982 <list compact="compact">
4983 <item>When the <prgn>postinst</prgn> script is run with a
4984 first argument of <tt>configure</tt>, the script must call
4985 <prgn>ldconfig</prgn>, and may optionally invoke
4986 <prgn>ldconfig</prgn> at other times.
4988 <item>When the <prgn>postrm</prgn> script is run with a
4989 first argument of <tt>remove</tt>, the script should call
4990 <prgn>ldconfig</prgn>.
4995 During install or upgrade, the preinst is called before
4996 the new files are installed, so calling "ldconfig" is
4997 pointless. The preinst of an existing package can also be
4998 called if an upgrade fails. However, this happens during
4999 the critical time when a shared libs may exist on-disk
5000 under a temporary name. Thus, it is dangerous and
5001 forbidden by current policy to call "ldconfig" at this
5006 When a package is installed or upgraded, "postinst
5007 configure" runs after the new files are safely on-disk.
5008 Since it is perfectly safe to invoke ldconfig
5009 unconditionally in a postinst, it is OK for a package to
5010 simply put ldconfig in its postinst without checking the
5011 argument. The postinst can also be called to recover from
5012 a failed upgrade. This happens before any new files are
5013 unpacked, so there is no reason to call "ldconfig" at this
5018 For a package that is being removed, prerm is
5019 called with all the files intact, so calling ldconfig is
5020 useless. The other calls to "prerm" happen in the case of
5021 upgrade at a time when all the files of the old package
5022 are on-disk, so again calling "ldconfig" is pointless.
5026 postrm, on the other hand, is called with the "remove"
5027 argument just after the files are removed, so this is
5028 the proper time to call "ldconfig" to notify the system
5029 of the fact that the shared libraries from the package
5030 are removed. The postrm can be called at several other
5031 times. At the time of "postrm purge", "postrm
5032 abort-install", or "postrm abort-upgrade", calling
5033 "ldconfig" is useless because the shared lib files are
5034 not on-disk. However, when "postrm" is invoked with
5035 arguments "upgrade", "failed-upgrade", or "disappear", a
5036 shared lib may exist on-disk under a temporary filename.
5044 <sect id="sharedlibs-support-files">
5045 <heading>Shared library support files</heading>
5048 If your package contains files whose names do not change with
5049 each change in the library shared object version, you must not
5050 put them in the shared library package. Otherwise, several
5051 versions of the shared library cannot be installed at the same
5052 time without filename clashes, making upgrades and transitions
5053 unnecessarily difficult.
5057 It is recommended that supporting files and run-time support
5058 programs that do not need to be invoked manually by users, but
5059 are nevertheless required for the package to function, be placed
5060 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
5061 preferably under <file>/usr/lib/</file><var>package-name</var>.
5062 If the program or file is architecture independent, the
5063 recommendation is for it to be placed in a subdirectory of
5064 <file>/usr/share</file> instead, preferably under
5065 <file>/usr/share/</file><var>package-name</var>. Following the
5066 <var>package-name</var> naming convention ensures that the file
5067 names change when the shared object version changes.
5071 Run-time support programs that use the shared library but are
5072 not required for the library to function or files used by the
5073 shared library that can be used by any version of the shared
5074 library package should instead be put in a separate package.
5075 This package might typically be named
5076 <package><var>libraryname</var>-tools</package>; note the
5077 absence of the <var>soversion</var> in the package name.
5081 Files and support programs only useful when compiling software
5082 against the library should be included in the development
5083 package for the library.<footnote>
5084 For example, a <file><var>package-name</var>-config</file>
5085 script or <package>pkg-config</package> configuration files.
5090 <sect id="sharedlibs-static">
5091 <heading>Static libraries</heading>
5094 The static library (<file><var>libraryname.a</var></file>)
5095 is usually provided in addition to the shared version.
5096 It is placed into the development package (see below).
5100 In some cases, it is acceptable for a library to be
5101 available in static form only; these cases include:
5103 <item>libraries for languages whose shared library support
5104 is immature or unstable</item>
5105 <item>libraries whose interfaces are in flux or under
5106 development (commonly the case when the library's
5107 major version number is zero, or where the ABI breaks
5108 across patchlevels)</item>
5109 <item>libraries which are explicitly intended to be
5110 available only in static form by their upstream
5115 <sect id="sharedlibs-dev">
5116 <heading>Development files</heading>
5119 The development files associated to a shared library need to be
5120 placed in a package called
5121 <package><var>libraryname</var><var>soversion</var>-dev</package>,
5122 or if you prefer only to support one development version at a
5123 time, <package><var>libraryname</var>-dev</package>.
5127 In case several development versions of a library exist, you may
5128 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5129 <ref id="conflicts">) to ensure that the user only installs one
5130 development version at a time (as different development versions are
5131 likely to have the same header files in them, which would cause a
5132 filename clash if both were installed).
5136 The development package should contain a symlink for the associated
5137 shared library without a version number. For example, the
5138 <package>libgdbm-dev</package> package should include a symlink
5139 from <file>/usr/lib/libgdbm.so</file> to
5140 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5141 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5142 <file>libgdbm.so</file> when compiling dynamically.
5146 <sect id="sharedlibs-intradeps">
5147 <heading>Dependencies between the packages of the same library</heading>
5150 Typically the development version should have an exact
5151 version dependency on the runtime library, to make sure that
5152 compilation and linking happens correctly. The
5153 <tt>${binary:Version}</tt> substitution variable can be
5154 useful for this purpose.
5156 Previously, <tt>${Source-Version}</tt> was used, but its name
5157 was confusing and it has been deprecated since dpkg 1.13.19.
5162 <sect id="sharedlibs-shlibdeps">
5163 <heading>Dependencies between the library and other packages -
5164 the <tt>shlibs</tt> system</heading>
5167 If a package contains a binary or library which links to a
5168 shared library, we must ensure that when the package is
5169 installed on the system, all of the libraries needed are
5170 also installed. This requirement led to the creation of the
5171 <tt>shlibs</tt> system, which is very simple in its design:
5172 any package which <em>provides</em> a shared library also
5173 provides information on the package dependencies required to
5174 ensure the presence of this library, and any package which
5175 <em>uses</em> a shared library uses this information to
5176 determine the dependencies it requires. The files which
5177 contain the mapping from shared libraries to the necessary
5178 dependency information are called <file>shlibs</file> files.
5182 Thus, when a package is built which contains any shared
5183 libraries, it must provide a <file>shlibs</file> file for other
5184 packages to use, and when a package is built which contains
5185 any shared libraries or compiled binaries, it must run
5186 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5187 on these to determine the libraries used and hence the
5188 dependencies needed by this package.<footnote>
5190 In the past, the shared libraries linked to were
5191 determined by calling <prgn>ldd</prgn>, but now
5192 <prgn>objdump</prgn> is used to do this. The only
5193 change this makes to package building is that
5194 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
5195 libraries, whereas in the past this was unnecessary.
5196 The rest of this footnote explains the advantage that
5201 We say that a binary <tt>foo</tt> <em>directly</em> uses
5202 a library <tt>libbar</tt> if it is explicitly linked
5203 with that library (that is, it uses the flag
5204 <tt>-lbar</tt> during the linking stage). Other
5205 libraries that are needed by <tt>libbar</tt> are linked
5206 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5207 linker will load them automatically when it loads
5208 <tt>libbar</tt>. A package should depend on
5209 the libraries it directly uses, and the dependencies for
5210 those libraries should automatically pull in the other
5215 Unfortunately, the <prgn>ldd</prgn> program shows both
5216 the directly and indirectly used libraries, meaning that
5217 the dependencies determined included both direct and
5218 indirect dependencies. The use of <prgn>objdump</prgn>
5219 avoids this problem by determining only the directly
5224 A good example of where this helps is the following. We
5225 could update <tt>libimlib</tt> with a new version that
5226 supports a new graphics format called dgf (but retaining
5227 the same major version number). If we used the old
5228 <prgn>ldd</prgn> method, every package that uses
5229 <tt>libimlib</tt> would need to be recompiled so it
5230 would also depend on <tt>libdgf</tt> or it wouldn't run
5231 due to missing symbols. However with the new system,
5232 packages using <tt>libimlib</tt> can rely on
5233 <tt>libimlib</tt> itself having the dependency on
5234 <tt>libdgf</tt> and so they would not need rebuilding.
5240 In the following sections, we will first describe where the
5241 various <tt>shlibs</tt> files are to be found, then how to
5242 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5243 file format and how to create them if your package contains a
5248 <heading>The <tt>shlibs</tt> files present on the system</heading>
5251 There are several places where <tt>shlibs</tt> files are
5252 found. The following list gives them in the order in which
5254 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5255 (The first one which gives the required information is used.)
5261 <p><file>debian/shlibs.local</file></p>
5264 This lists overrides for this package. Its use is
5265 described below (see <ref id="shlibslocal">).
5270 <p><file>/etc/dpkg/shlibs.override</file></p>
5273 This lists global overrides. This list is normally
5274 empty. It is maintained by the local system
5280 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5283 When packages are being built, any
5284 <file>debian/shlibs</file> files are copied into the
5285 control file area of the temporary build directory and
5286 given the name <file>shlibs</file>. These files give
5287 details of any shared libraries included in the
5289 An example may help here. Let us say that the
5290 source package <tt>foo</tt> generates two binary
5291 packages, <tt>libfoo2</tt> and
5292 <tt>foo-runtime</tt>. When building the binary
5293 packages, the two packages are created in the
5294 directories <file>debian/libfoo2</file> and
5295 <file>debian/foo-runtime</file> respectively.
5296 (<file>debian/tmp</file> could be used instead of one
5297 of these.) Since <tt>libfoo2</tt> provides the
5298 <tt>libfoo</tt> shared library, it will require a
5299 <tt>shlibs</tt> file, which will be installed in
5300 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
5302 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
5303 when <prgn>dpkg-shlibdeps</prgn> is run on the
5305 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
5307 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5308 determine whether <tt>foo-prog</tt>'s library
5309 dependencies are satisfied by any of the libraries
5310 provided by <tt>libfoo2</tt>. For this reason,
5311 <prgn>dpkg-shlibdeps</prgn> must only be run once
5312 all of the individual binary packages'
5313 <tt>shlibs</tt> files have been installed into the
5320 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5323 These are the <file>shlibs</file> files corresponding to
5324 all of the packages installed on the system, and are
5325 maintained by the relevant package maintainers.
5330 <p><file>/etc/dpkg/shlibs.default</file></p>
5333 This file lists any shared libraries whose packages
5334 have failed to provide correct <file>shlibs</file> files.
5335 It was used when the <file>shlibs</file> setup was first
5336 introduced, but it is now normally empty. It is
5337 maintained by the <tt>dpkg</tt> maintainer.
5345 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5346 <file>shlibs</file> files</heading>
5350 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5351 into your <file>debian/rules</file> file. If your package
5352 contains only compiled binaries and libraries (but no scripts),
5353 you can use a command such as:
5354 <example compact="compact">
5355 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5356 debian/tmp/usr/lib/*
5358 Otherwise, you will need to explicitly list the compiled
5359 binaries and libraries.<footnote>
5360 If you are using <tt>debhelper</tt>, the
5361 <prgn>dh_shlibdeps</prgn> program will do this work for
5362 you. It will also correctly handle multi-binary
5368 This command puts the dependency information into the
5369 <file>debian/substvars</file> file, which is then used by
5370 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5371 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5372 field in the control file for this to work.
5376 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
5377 done. If it does complain you might need to create your own
5378 <file>debian/shlibs.local</file> file, as explained below (see
5379 <ref id="shlibslocal">).
5383 If you have multiple binary packages, you will need to call
5384 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5385 compiled libraries or binaries. In such a case, you will
5386 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5387 utilities to specify a different <file>substvars</file> file.
5391 If you are creating a udeb for use in the Debian Installer,
5392 you will need to specify that <prgn>dpkg-shlibdeps</prgn>
5393 should use the dependency line of type <tt>udeb</tt> by
5394 adding the <tt>-tudeb</tt> option<footnote>
5395 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5396 will automatically add this option if it knows it is
5398 </footnote>. If there is no dependency line of type <tt>udeb</tt>
5399 in the <file>shlibs</file> file, <prgn>dpkg-shlibdeps</prgn> will
5400 fall back to the regular dependency line.
5404 For more details on dpkg-shlibdeps, please see
5405 <ref id="pkg-dpkg-shlibdeps"> and
5406 <manref name="dpkg-shlibdeps" section="1">.
5411 <heading>The <file>shlibs</file> File Format</heading>
5414 Each <file>shlibs</file> file has the same format. Lines
5415 beginning with <tt>#</tt> are considered to be comments and
5416 are ignored. Each line is of the form:
5417 <example compact="compact">
5418 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5423 We will explain this by reference to the example of the
5424 <tt>zlib1g</tt> package, which (at the time of writing)
5425 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5429 <var>type</var> is an optional element that indicates the type
5430 of package for which the line is valid. The only type currently
5431 in use is <tt>udeb</tt>. The colon and space after the type are
5436 <var>library-name</var> is the name of the shared library,
5437 in this case <tt>libz</tt>. (This must match the name part
5438 of the soname, see below.)
5442 <var>soname-version</var> is the version part of the soname of
5443 the library. The soname is the thing that must exactly match
5444 for the library to be recognized by the dynamic linker, and is
5446 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5447 example, <tt>libz.so.1</tt>.<footnote>
5448 This can be determined using the command
5449 <example compact="compact">
5450 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5453 The version part is the part which comes after
5454 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
5458 <var>dependencies</var> has the same syntax as a dependency
5459 field in a binary package control file. It should give
5460 details of which packages are required to satisfy a binary
5461 built against the version of the library contained in the
5462 package. See <ref id="depsyntax"> for details.
5466 In our example, if the first version of the <tt>zlib1g</tt>
5467 package which contained a minor number of at least
5468 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5469 <tt>shlibs</tt> entry for this library could say:
5470 <example compact="compact">
5471 libz 1 zlib1g (>= 1:1.1.3)
5473 The version-specific dependency is to avoid warnings from
5474 the dynamic linker about using older shared libraries with
5479 As zlib1g also provides a udeb containing the shared library,
5480 there would also be a second line:
5481 <example compact="compact">
5482 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5488 <heading>Providing a <file>shlibs</file> file</heading>
5491 If your package provides a shared library, you need to create
5492 a <file>shlibs</file> file following the format described above.
5493 It is usual to call this file <file>debian/shlibs</file> (but if
5494 you have multiple binary packages, you might want to call it
5495 <file>debian/shlibs.<var>package</var></file> instead). Then
5496 let <file>debian/rules</file> install it in the control area:
5497 <example compact="compact">
5498 install -m644 debian/shlibs debian/tmp/DEBIAN
5500 or, in the case of a multi-binary package:
5501 <example compact="compact">
5502 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5504 An alternative way of doing this is to create the
5505 <file>shlibs</file> file in the control area directly from
5506 <file>debian/rules</file> without using a <file>debian/shlibs</file>
5507 file at all,<footnote>
5508 This is what <prgn>dh_makeshlibs</prgn> in the
5509 <tt>debhelper</tt> suite does. If your package also has a udeb
5510 that provides a shared library, <prgn>dh_makeshlibs</prgn> can
5511 automatically generate the <tt>udeb:</tt> lines if you specify
5512 the name of the udeb with the <tt>--add-udeb</tt> option.
5514 since the <file>debian/shlibs</file> file itself is ignored by
5515 <prgn>dpkg-shlibdeps</prgn>.
5519 As <prgn>dpkg-shlibdeps</prgn> reads the
5520 <file>DEBIAN/shlibs</file> files in all of the binary packages
5521 being built from this source package, all of the
5522 <file>DEBIAN/shlibs</file> files should be installed before
5523 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5528 <sect1 id="shlibslocal">
5529 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
5532 This file is intended only as a <em>temporary</em> fix if
5533 your binaries or libraries depend on a library whose package
5534 does not yet provide a correct <file>shlibs</file> file.
5538 We will assume that you are trying to package a binary
5539 <tt>foo</tt>. When you try running
5540 <prgn>dpkg-shlibdeps</prgn> you get the following error
5541 message (<tt>-O</tt> displays the dependency information on
5542 <tt>stdout</tt> instead of writing it to
5543 <tt>debian/substvars</tt>, and the lines have been wrapped
5544 for ease of reading):
5545 <example compact="compact">
5546 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
5547 dpkg-shlibdeps: warning: unable to find dependency
5548 information for shared library libbar (soname 1,
5549 path /usr/lib/libbar.so.1, dependency field Depends)
5550 shlibs:Depends=libc6 (>= 2.2.2-2)
5552 You can then run <prgn>ldd</prgn> on the binary to find the
5553 full location of the library concerned:
5554 <example compact="compact">
5556 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5557 libc.so.6 => /lib/libc.so.6 (0x40032000)
5558 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5560 So the <prgn>foo</prgn> binary depends on the
5561 <prgn>libbar</prgn> shared library, but no package seems to
5562 provide a <file>*.shlibs</file> file handling
5563 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5564 determine the package responsible:
5565 <example compact="compact">
5566 $ dpkg -S /usr/lib/libbar.so.1
5567 bar1: /usr/lib/libbar.so.1
5568 $ dpkg -s bar1 | grep Version
5571 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5572 is the one we are using. Now we can file a bug against the
5573 <tt>bar1</tt> package and create our own
5574 <file>debian/shlibs.local</file> to locally fix the problem.
5575 Including the following line into your
5576 <file>debian/shlibs.local</file> file:
5577 <example compact="compact">
5578 libbar 1 bar1 (>= 1.0-1)
5580 should allow the package build to work.
5584 As soon as the maintainer of <tt>bar1</tt> provides a
5585 correct <file>shlibs</file> file, you should remove this line
5586 from your <file>debian/shlibs.local</file> file. (You should
5587 probably also then have a versioned <tt>Build-Depends</tt>
5588 on <tt>bar1</tt> to help ensure that others do not have the
5589 same problem building your package.)
5598 <chapt id="opersys"><heading>The Operating System</heading>
5601 <heading>File system hierarchy</heading>
5605 <heading>File System Structure</heading>
5608 The location of all installed files and directories must
5609 comply with the Filesystem Hierarchy Standard (FHS),
5610 version 2.3, with the exceptions noted below, and except
5611 where doing so would violate other terms of Debian
5612 Policy. The following exceptions to the FHS apply:
5617 The optional rules related to user specific
5618 configuration files for applications are stored in
5619 the user's home directory are relaxed. It is
5620 recommended that such files start with the
5621 '<tt>.</tt>' character (a "dot file"), and if an
5622 application needs to create more than one dot file
5623 then the preferred placement is in a subdirectory
5624 with a name starting with a '.' character, (a "dot
5625 directory"). In this case it is recommended the
5626 configuration files not start with the '.'
5632 The requirement for amd64 to use <file>/lib64</file>
5633 for 64 bit binaries is removed.
5638 The requirement for object files, internal binaries, and
5639 libraries, including <file>libc.so.*</file>, to be located
5640 directly under <file>/lib{,32}</file> and
5641 <file>/usr/lib{,32}</file> is amended, permitting files
5642 to instead be installed to
5643 <file>/lib/<var>triplet</var></file> and
5644 <file>/usr/lib/<var>triplet</var></file>, where
5645 <tt><var>triplet</var></tt> is the value returned by
5646 <tt>dpkg-architecture -qDEB_HOST_GNU_TYPE</tt> for the
5647 architecture of the package. Packages may <em>not</em>
5648 install files to any <var>triplet</var> path other
5649 than the one matching the architecture of that package;
5650 for instance, an <tt>Architecture: amd64</tt> package
5651 containing 32-bit x86 libraries may not install these
5652 libraries to <file>/usr/lib/i486-linux-gnu</file>.
5654 This is necessary in order to reserve the directories for
5655 use in cross-installation of library packages from other
5656 architectures, as part of the planned deployment of
5661 Applications may also use a single subdirectory under
5662 <file>/usr/lib/<var>triplet</var></file>.
5665 The execution time linker/loader, ld*, must still be made
5666 available in the existing location under /lib or /lib64
5667 since this is part of the ELF ABI for the architecture.
5672 The requirement that
5673 <file>/usr/local/share/man</file> be "synonymous"
5674 with <file>/usr/local/man</file> is relaxed to a
5679 The requirement that windowmanagers with a single
5680 configuration file call it <file>system.*wmrc</file>
5681 is removed, as is the restriction that the window
5682 manager subdirectory be named identically to the
5683 window manager name itself.
5688 The requirement that boot manager configuration
5689 files live in <file>/etc</file>, or at least are
5690 symlinked there, is relaxed to a recommendation.
5695 The following directories in the root filesystem are
5696 additionally allowed: <file>/sys</file> and
5697 <file>/selinux</file>. <footnote>These directories
5698 are used as mount points to mount virtual filesystems
5699 to get access to kernel information.</footnote>
5706 The version of this document referred here can be
5707 found in the <tt>debian-policy</tt> package or on <url
5708 id="http://www.debian.org/doc/packaging-manuals/fhs/"
5709 name="FHS (Debian copy)"> alongside this manual (or, if
5710 you have the <package>debian-policy</package> installed,
5712 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5713 (local copy)">). The
5714 latest version, which may be a more recent version, may
5716 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5717 Specific questions about following the standard may be
5718 asked on the <tt>debian-devel</tt> mailing list, or
5719 referred to the FHS mailing list (see the
5720 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5726 <heading>Site-specific programs</heading>
5729 As mandated by the FHS, packages must not place any
5730 files in <file>/usr/local</file>, either by putting them in
5731 the file system archive to be unpacked by <prgn>dpkg</prgn>
5732 or by manipulating them in their maintainer scripts.
5736 However, the package may create empty directories below
5737 <file>/usr/local</file> so that the system administrator knows
5738 where to place site-specific files. These are not
5739 directories <em>in</em> <file>/usr/local</file>, but are
5740 children of directories in <file>/usr/local</file>. These
5741 directories (<file>/usr/local/*/dir/</file>)
5742 should be removed on package removal if they are
5747 Note that this applies only to
5748 directories <em>below</em> <file>/usr/local</file>,
5749 not <em>in</em> <file>/usr/local</file>. Packages must
5750 not create sub-directories in the
5751 directory <file>/usr/local</file> itself, except those
5752 listed in FHS, section 4.5. However, you may create
5753 directories below them as you wish. You must not remove
5754 any of the directories listed in 4.5, even if you created
5759 Since <file>/usr/local</file> can be mounted read-only from a
5760 remote server, these directories must be created and
5761 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5762 maintainer scripts and not be included in the
5763 <file>.deb</file> archive. These scripts must not fail if
5764 either of these operations fail.
5768 For example, the <tt>emacsen-common</tt> package could
5769 contain something like
5770 <example compact="compact">
5771 if [ ! -e /usr/local/share/emacs ]
5773 if mkdir /usr/local/share/emacs 2>/dev/null
5775 chown root:staff /usr/local/share/emacs
5776 chmod 2775 /usr/local/share/emacs
5780 in its <prgn>postinst</prgn> script, and
5781 <example compact="compact">
5782 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5783 rmdir /usr/local/share/emacs 2>/dev/null || true
5785 in the <prgn>prerm</prgn> script. (Note that this form is
5786 used to ensure that if the script is interrupted, the
5787 directory <file>/usr/local/share/emacs</file> will still be
5792 If you do create a directory in <file>/usr/local</file> for
5793 local additions to a package, you should ensure that
5794 settings in <file>/usr/local</file> take precedence over the
5795 equivalents in <file>/usr</file>.
5799 However, because <file>/usr/local</file> and its contents are
5800 for exclusive use of the local administrator, a package
5801 must not rely on the presence or absence of files or
5802 directories in <file>/usr/local</file> for normal operation.
5806 The <file>/usr/local</file> directory itself and all the
5807 subdirectories created by the package should (by default) have
5808 permissions 2775 (group-writable and set-group-id) and be
5809 owned by <tt>root:staff</tt>.
5814 <heading>The system-wide mail directory</heading>
5816 The system-wide mail directory
5817 is <file>/var/mail</file>. This directory is part of the
5818 base system and should not be owned by any particular mail
5819 agents. The use of the old
5820 location <file>/var/spool/mail</file> is deprecated, even
5821 though the spool may still be physically located there.
5827 <heading>Users and groups</heading>
5830 <heading>Introduction</heading>
5832 The Debian system can be configured to use either plain or
5837 Some user ids (UIDs) and group ids (GIDs) are reserved
5838 globally for use by certain packages. Because some
5839 packages need to include files which are owned by these
5840 users or groups, or need the ids compiled into binaries,
5841 these ids must be used on any Debian system only for the
5842 purpose for which they are allocated. This is a serious
5843 restriction, and we should avoid getting in the way of
5844 local administration policies. In particular, many sites
5845 allocate users and/or local system groups starting at 100.
5849 Apart from this we should have dynamically allocated ids,
5850 which should by default be arranged in some sensible
5851 order, but the behavior should be configurable.
5855 Packages other than <tt>base-passwd</tt> must not modify
5856 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5857 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5862 <heading>UID and GID classes</heading>
5864 The UID and GID numbers are divided into classes as
5870 Globally allocated by the Debian project, the same
5871 on every Debian system. These ids will appear in
5872 the <file>passwd</file> and <file>group</file> files of all
5873 Debian systems, new ids in this range being added
5874 automatically as the <tt>base-passwd</tt> package is
5879 Packages which need a single statically allocated
5880 uid or gid should use one of these; their
5881 maintainers should ask the <tt>base-passwd</tt>
5889 Dynamically allocated system users and groups.
5890 Packages which need a user or group, but can have
5891 this user or group allocated dynamically and
5892 differently on each system, should use <tt>adduser
5893 --system</tt> to create the group and/or user.
5894 <prgn>adduser</prgn> will check for the existence of
5895 the user or group, and if necessary choose an unused
5896 id based on the ranges specified in
5897 <file>adduser.conf</file>.
5901 <tag>1000-59999:</tag>
5904 Dynamically allocated user accounts. By default
5905 <prgn>adduser</prgn> will choose UIDs and GIDs for
5906 user accounts in this range, though
5907 <file>adduser.conf</file> may be used to modify this
5912 <tag>60000-64999:</tag>
5915 Globally allocated by the Debian project, but only
5916 created on demand. The ids are allocated centrally
5917 and statically, but the actual accounts are only
5918 created on users' systems on demand.
5922 These ids are for packages which are obscure or
5923 which require many statically-allocated ids. These
5924 packages should check for and create the accounts in
5925 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5926 <prgn>adduser</prgn> if it has this facility) if
5927 necessary. Packages which are likely to require
5928 further allocations should have a "hole" left after
5929 them in the allocation, to give them room to
5934 <tag>65000-65533:</tag>
5942 User <tt>nobody</tt>. The corresponding gid refers
5943 to the group <tt>nogroup</tt>.
5950 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5951 not</em> be used, because it is the error return
5960 <sect id="sysvinit">
5961 <heading>System run levels and <file>init.d</file> scripts</heading>
5963 <sect1 id="/etc/init.d">
5964 <heading>Introduction</heading>
5967 The <file>/etc/init.d</file> directory contains the scripts
5968 executed by <prgn>init</prgn> at boot time and when the
5969 init state (or "runlevel") is changed (see <manref
5970 name="init" section="8">).
5974 There are at least two different, yet functionally
5975 equivalent, ways of handling these scripts. For the sake
5976 of simplicity, this document describes only the symbolic
5977 link method. However, it must not be assumed by maintainer
5978 scripts that this method is being used, and any automated
5979 manipulation of the various runlevel behaviors by
5980 maintainer scripts must be performed using
5981 <prgn>update-rc.d</prgn> as described below and not by
5982 manually installing or removing symlinks. For information
5983 on the implementation details of the other method,
5984 implemented in the <tt>file-rc</tt> package, please refer
5985 to the documentation of that package.
5989 These scripts are referenced by symbolic links in the
5990 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5991 runlevels, <prgn>init</prgn> looks in the directory
5992 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5993 execute, where <tt><var>n</var></tt> is the runlevel that
5994 is being changed to, or <tt>S</tt> for the boot-up
5999 The names of the links all have the form
6000 <file>S<var>mm</var><var>script</var></file> or
6001 <file>K<var>mm</var><var>script</var></file> where
6002 <var>mm</var> is a two-digit number and <var>script</var>
6003 is the name of the script (this should be the same as the
6004 name of the actual script in <file>/etc/init.d</file>).
6008 When <prgn>init</prgn> changes runlevel first the targets
6009 of the links whose names start with a <tt>K</tt> are
6010 executed, each with the single argument <tt>stop</tt>,
6011 followed by the scripts prefixed with an <tt>S</tt>, each
6012 with the single argument <tt>start</tt>. (The links are
6013 those in the <file>/etc/rc<var>n</var>.d</file> directory
6014 corresponding to the new runlevel.) The <tt>K</tt> links
6015 are responsible for killing services and the <tt>S</tt>
6016 link for starting services upon entering the runlevel.
6020 For example, if we are changing from runlevel 2 to
6021 runlevel 3, init will first execute all of the <tt>K</tt>
6022 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
6023 all of the <tt>S</tt> prefixed scripts in that directory.
6024 The links starting with <tt>K</tt> will cause the
6025 referred-to file to be executed with an argument of
6026 <tt>stop</tt>, and the <tt>S</tt> links with an argument
6031 The two-digit number <var>mm</var> is used to determine
6032 the order in which to run the scripts: low-numbered links
6033 have their scripts run first. For example, the
6034 <tt>K20</tt> scripts will be executed before the
6035 <tt>K30</tt> scripts. This is used when a certain service
6036 must be started before another. For example, the name
6037 server <prgn>bind</prgn> might need to be started before
6038 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
6039 can set up its access lists. In this case, the script
6040 that starts <prgn>bind</prgn> would have a lower number
6041 than the script that starts <prgn>inn</prgn> so that it
6043 <example compact="compact">
6050 The two runlevels 0 (halt) and 6 (reboot) are slightly
6051 different. In these runlevels, the links with an
6052 <tt>S</tt> prefix are still called after those with a
6053 <tt>K</tt> prefix, but they too are called with the single
6054 argument <tt>stop</tt>.
6059 <heading>Writing the scripts</heading>
6062 Packages that include daemons for system services should
6063 place scripts in <file>/etc/init.d</file> to start or stop
6064 services at boot time or during a change of runlevel.
6065 These scripts should be named
6066 <file>/etc/init.d/<var>package</var></file>, and they should
6067 accept one argument, saying what to do:
6070 <tag><tt>start</tt></tag>
6071 <item>start the service,</item>
6073 <tag><tt>stop</tt></tag>
6074 <item>stop the service,</item>
6076 <tag><tt>restart</tt></tag>
6077 <item>stop and restart the service if it's already running,
6078 otherwise start the service</item>
6080 <tag><tt>reload</tt></tag>
6081 <item><p>cause the configuration of the service to be
6082 reloaded without actually stopping and restarting
6085 <tag><tt>force-reload</tt></tag>
6086 <item>cause the configuration to be reloaded if the
6087 service supports this, otherwise restart the
6091 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
6092 <tt>force-reload</tt> options should be supported by all
6093 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
6098 The <file>init.d</file> scripts must ensure that they will
6099 behave sensibly (i.e., returning success and not starting
6100 multiple copies of a service) if invoked with <tt>start</tt>
6101 when the service is already running, or with <tt>stop</tt>
6102 when it isn't, and that they don't kill unfortunately-named
6103 user processes. The best way to achieve this is usually to
6104 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
6109 If a service reloads its configuration automatically (as
6110 in the case of <prgn>cron</prgn>, for example), the
6111 <tt>reload</tt> option of the <file>init.d</file> script
6112 should behave as if the configuration has been reloaded
6117 The <file>/etc/init.d</file> scripts must be treated as
6118 configuration files, either (if they are present in the
6119 package, that is, in the .deb file) by marking them as
6120 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
6121 by managing them correctly in the maintainer scripts (see
6122 <ref id="config-files">). This is important since we want
6123 to give the local system administrator the chance to adapt
6124 the scripts to the local system, e.g., to disable a
6125 service without de-installing the package, or to specify
6126 some special command line options when starting a service,
6127 while making sure their changes aren't lost during the next
6132 These scripts should not fail obscurely when the
6133 configuration files remain but the package has been
6134 removed, as configuration files remain on the system after
6135 the package has been removed. Only when <prgn>dpkg</prgn>
6136 is executed with the <tt>--purge</tt> option will
6137 configuration files be removed. In particular, as the
6138 <file>/etc/init.d/<var>package</var></file> script itself is
6139 usually a <tt>conffile</tt>, it will remain on the system
6140 if the package is removed but not purged. Therefore, you
6141 should include a <tt>test</tt> statement at the top of the
6143 <example compact="compact">
6144 test -f <var>program-executed-later-in-script</var> || exit 0
6149 Often there are some variables in the <file>init.d</file>
6150 scripts whose values control the behavior of the scripts,
6151 and which a system administrator is likely to want to
6152 change. As the scripts themselves are frequently
6153 <tt>conffile</tt>s, modifying them requires that the
6154 administrator merge in their changes each time the package
6155 is upgraded and the <tt>conffile</tt> changes. To ease
6156 the burden on the system administrator, such configurable
6157 values should not be placed directly in the script.
6158 Instead, they should be placed in a file in
6159 <file>/etc/default</file>, which typically will have the same
6160 base name as the <file>init.d</file> script. This extra file
6161 should be sourced by the script when the script runs. It
6162 must contain only variable settings and comments in SUSv3
6163 <prgn>sh</prgn> format. It may either be a
6164 <tt>conffile</tt> or a configuration file maintained by
6165 the package maintainer scripts. See <ref id="config-files">
6170 To ensure that vital configurable values are always
6171 available, the <file>init.d</file> script should set default
6172 values for each of the shell variables it uses, either
6173 before sourcing the <file>/etc/default/</file> file or
6174 afterwards using something like the <tt>:
6175 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6176 script must behave sensibly and not fail if the
6177 <file>/etc/default</file> file is deleted.
6181 <file>/var/run</file> and <file>/var/lock</file> may be mounted
6182 as temporary filesystems<footnote>
6183 For example, using the <tt>RAMRUN</tt> and <tt>RAMLOCK</tt>
6184 options in <file>/etc/default/rcS</file>.
6185 </footnote>, so the <file>init.d</file> scripts must handle this
6186 correctly. This will typically amount to creating any required
6187 subdirectories dynamically when the <file>init.d</file> script
6188 is run, rather than including them in the package and relying on
6189 <prgn>dpkg</prgn> to create them.
6194 <heading>Interfacing with the initscript system</heading>
6197 Maintainers should use the abstraction layer provided by
6198 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6199 programs to deal with initscripts in their packages'
6200 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6201 and <prgn>postrm</prgn>.
6205 Directly managing the /etc/rc?.d links and directly
6206 invoking the <file>/etc/init.d/</file> initscripts should
6207 be done only by packages providing the initscript
6208 subsystem (such as <prgn>sysv-rc</prgn> and
6209 <prgn>file-rc</prgn>).
6213 <heading>Managing the links</heading>
6216 The program <prgn>update-rc.d</prgn> is provided for
6217 package maintainers to arrange for the proper creation and
6218 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6219 or their functional equivalent if another method is being
6220 used. This may be used by maintainers in their packages'
6221 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6225 You must not include any <file>/etc/rc<var>n</var>.d</file>
6226 symbolic links in the actual archive or manually create or
6227 remove the symbolic links in maintainer scripts; you must
6228 use the <prgn>update-rc.d</prgn> program instead. (The
6229 former will fail if an alternative method of maintaining
6230 runlevel information is being used.) You must not include
6231 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6232 in the archive either. (Only the <tt>sysvinit</tt>
6237 By default <prgn>update-rc.d</prgn> will start services in
6238 each of the multi-user state runlevels (2, 3, 4, and 5)
6239 and stop them in the halt runlevel (0), the single-user
6240 runlevel (1) and the reboot runlevel (6). The system
6241 administrator will have the opportunity to customize
6242 runlevels by simply adding, moving, or removing the
6243 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6244 symbolic links are being used, or by modifying
6245 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6250 To get the default behavior for your package, put in your
6251 <prgn>postinst</prgn> script
6252 <example compact="compact">
6253 update-rc.d <var>package</var> defaults
6255 and in your <prgn>postrm</prgn>
6256 <example compact="compact">
6257 if [ "$1" = purge ]; then
6258 update-rc.d <var>package</var> remove
6260 </example>. Note that if your package changes runlevels
6261 or priority, you may have to remove and recreate the links,
6262 since otherwise the old links may persist. Refer to the
6263 documentation of <prgn>update-rc.d</prgn>.
6267 This will use a default sequence number of 20. If it does
6268 not matter when or in which order the <file>init.d</file>
6269 script is run, use this default. If it does, then you
6270 should talk to the maintainer of the <prgn>sysvinit</prgn>
6271 package or post to <tt>debian-devel</tt>, and they will
6272 help you choose a number.
6276 For more information about using <tt>update-rc.d</tt>,
6277 please consult its man page <manref name="update-rc.d"
6283 <heading>Running initscripts</heading>
6285 The program <prgn>invoke-rc.d</prgn> is provided to make
6286 it easier for package maintainers to properly invoke an
6287 initscript, obeying runlevel and other locally-defined
6288 constraints that might limit a package's right to start,
6289 stop and otherwise manage services. This program may be
6290 used by maintainers in their packages' scripts.
6294 The package maintainer scripts must use
6295 <prgn>invoke-rc.d</prgn> to invoke the
6296 <file>/etc/init.d/*</file> initscripts, instead of
6297 calling them directly.
6301 By default, <prgn>invoke-rc.d</prgn> will pass any
6302 action requests (start, stop, reload, restart...) to the
6303 <file>/etc/init.d</file> script, filtering out requests
6304 to start or restart a service out of its intended
6309 Most packages will simply need to change:
6310 <example compact="compact">/etc/init.d/<package>
6311 <action></example> in their <prgn>postinst</prgn>
6312 and <prgn>prerm</prgn> scripts to:
6313 <example compact="compact">
6314 if which invoke-rc.d >/dev/null 2>&1; then
6315 invoke-rc.d <var>package</var> <action>
6317 /etc/init.d/<var>package</var> <action>
6323 A package should register its initscript services using
6324 <prgn>update-rc.d</prgn> before it tries to invoke them
6325 using <prgn>invoke-rc.d</prgn>. Invocation of
6326 unregistered services may fail.
6330 For more information about using
6331 <prgn>invoke-rc.d</prgn>, please consult its man page
6332 <manref name="invoke-rc.d" section="8">.
6338 <heading>Boot-time initialization</heading>
6341 There used to be another directory, <file>/etc/rc.boot</file>,
6342 which contained scripts which were run once per machine
6343 boot. This has been deprecated in favour of links from
6344 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6345 described in <ref id="/etc/init.d">. Packages must not
6346 place files in <file>/etc/rc.boot</file>.
6351 <heading>Example</heading>
6354 An example on which you can base your
6355 <file>/etc/init.d</file> scripts is found in
6356 <file>/etc/init.d/skeleton</file>.
6363 <heading>Console messages from <file>init.d</file> scripts</heading>
6366 This section describes the formats to be used for messages
6367 written to standard output by the <file>/etc/init.d</file>
6368 scripts. The intent is to improve the consistency of
6369 Debian's startup and shutdown look and feel. For this
6370 reason, please look very carefully at the details. We want
6371 the messages to have the same format in terms of wording,
6372 spaces, punctuation and case of letters.
6376 Here is a list of overall rules that should be used for
6377 messages generated by <file>/etc/init.d</file> scripts.
6383 The message should fit in one line (fewer than 80
6384 characters), start with a capital letter and end with
6385 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6389 If the script is performing some time consuming task in
6390 the background (not merely starting or stopping a
6391 program, for instance), an ellipsis (three dots:
6392 <tt>...</tt>) should be output to the screen, with no
6393 leading or tailing whitespace or line feeds.
6397 The messages should appear as if the computer is telling
6398 the user what it is doing (politely :-), but should not
6399 mention "it" directly. For example, instead of:
6400 <example compact="compact">
6401 I'm starting network daemons: nfsd mountd.
6403 the message should say
6404 <example compact="compact">
6405 Starting network daemons: nfsd mountd.
6412 <tt>init.d</tt> script should use the following standard
6413 message formats for the situations enumerated below.
6419 <p>When daemons are started</p>
6422 If the script starts one or more daemons, the output
6423 should look like this (a single line, no leading
6425 <example compact="compact">
6426 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6428 The <var>description</var> should describe the
6429 subsystem the daemon or set of daemons are part of,
6430 while <var>daemon-1</var> up to <var>daemon-n</var>
6431 denote each daemon's name (typically the file name of
6436 For example, the output of <file>/etc/init.d/lpd</file>
6438 <example compact="compact">
6439 Starting printer spooler: lpd.
6444 This can be achieved by saying
6445 <example compact="compact">
6446 echo -n "Starting printer spooler: lpd"
6447 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6450 in the script. If there are more than one daemon to
6451 start, the output should look like this:
6452 <example compact="compact">
6453 echo -n "Starting remote file system services:"
6454 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6455 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6456 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6459 This makes it possible for the user to see what is
6460 happening and when the final daemon has been started.
6461 Care should be taken in the placement of white spaces:
6462 in the example above the system administrators can
6463 easily comment out a line if they don't want to start
6464 a specific daemon, while the displayed message still
6470 <p>When a system parameter is being set</p>
6473 If you have to set up different system parameters
6474 during the system boot, you should use this format:
6475 <example compact="compact">
6476 Setting <var>parameter</var> to "<var>value</var>".
6481 You can use a statement such as the following to get
6483 <example compact="compact">
6484 echo "Setting DNS domainname to \"$domainname\"."
6489 Note that the same symbol (<tt>"</tt>) <!-- " --> is used
6490 for the left and right quotation marks. A grave accent
6491 (<tt>`</tt>) is not a quote character; neither is an
6492 apostrophe (<tt>'</tt>).
6497 <p>When a daemon is stopped or restarted</p>
6500 When you stop or restart a daemon, you should issue a
6501 message identical to the startup message, except that
6502 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6503 or <tt>Restarting</tt> respectively.
6507 For example, stopping the printer daemon will look like
6509 <example compact="compact">
6510 Stopping printer spooler: lpd.
6516 <p>When something is executed</p>
6519 There are several examples where you have to run a
6520 program at system startup or shutdown to perform a
6521 specific task, for example, setting the system's clock
6522 using <prgn>netdate</prgn> or killing all processes
6523 when the system shuts down. Your message should look
6525 <example compact="compact">
6526 Doing something very useful...done.
6528 You should print the <tt>done.</tt> immediately after
6529 the job has been completed, so that the user is
6530 informed why they have to wait. You can get this
6532 <example compact="compact">
6533 echo -n "Doing something very useful..."
6542 <p>When the configuration is reloaded</p>
6545 When a daemon is forced to reload its configuration
6546 files you should use the following format:
6547 <example compact="compact">
6548 Reloading <var>description</var> configuration...done.
6550 where <var>description</var> is the same as in the
6551 daemon starting message.
6559 <heading>Cron jobs</heading>
6562 Packages must not modify the configuration file
6563 <file>/etc/crontab</file>, and they must not modify the files in
6564 <file>/var/spool/cron/crontabs</file>.</p>
6567 If a package wants to install a job that has to be executed
6568 via cron, it should place a file with the name of the
6569 package in one or more of the following directories:
6570 <example compact="compact">
6576 As these directory names imply, the files within them are
6577 executed on an hourly, daily, weekly, or monthly basis,
6578 respectively. The exact times are listed in
6579 <file>/etc/crontab</file>.</p>
6582 All files installed in any of these directories must be
6583 scripts (e.g., shell scripts or Perl scripts) so that they
6584 can easily be modified by the local system administrator.
6585 In addition, they must be treated as configuration files.
6589 If a certain job has to be executed at some other frequency or
6590 at a specific time, the package should install a file
6591 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6592 same syntax as <file>/etc/crontab</file> and is processed by
6593 <prgn>cron</prgn> automatically. The file must also be
6594 treated as a configuration file. (Note that entries in the
6595 <file>/etc/cron.d</file> directory are not handled by
6596 <prgn>anacron</prgn>. Thus, you should only use this
6597 directory for jobs which may be skipped if the system is not
6600 Unlike <file>crontab</file> files described in the IEEE Std
6601 1003.1-2008 (POSIX.1) available from
6602 <url id="http://www.opengroup.org/onlinepubs/9699919799/"
6603 name="The Open Group">, the files in
6604 <file>/etc/cron.d</file> and the file
6605 <file>/etc/crontab</file> have seven fields; namely:
6607 <item>Minute [0,59]</item>
6608 <item>Hour [0,23]</item>
6609 <item>Day of the month [1,31]</item>
6610 <item>Month of the year [1,12]</item>
6611 <item>Day of the week ([0,6] with 0=Sunday)</item>
6612 <item>Username</item>
6613 <item>Command to be run</item>
6615 Ranges of numbers are allowed. Ranges are two numbers
6616 separated with a hyphen. The specified range is inclusive.
6617 Lists are allowed. A list is a set of numbers (or ranges)
6618 separated by commas. Step values can be used in conjunction
6623 The scripts or <tt>crontab</tt> entries in these directories should
6624 check if all necessary programs are installed before they
6625 try to execute them. Otherwise, problems will arise when a
6626 package was removed but not purged since configuration files
6627 are kept on the system in this situation.
6631 Any <tt>cron</tt> daemon must provide
6632 <file>/usr/bin/crontab</file> and support normal
6633 <tt>crontab</tt> entries as specified in POSIX. The daemon
6634 must also support names for days and months, ranges, and
6635 step values. It has to support <file>/etc/crontab</file>,
6636 and correctly execute the scripts in
6637 <file>/etc/cron.d</file>. The daemon must also correctly
6639 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>.
6644 <heading>Menus</heading>
6647 The Debian <tt>menu</tt> package provides a standard
6648 interface between packages providing applications and
6649 <em>menu programs</em> (either X window managers or
6650 text-based menu programs such as <prgn>pdmenu</prgn>).
6654 All packages that provide applications that need not be
6655 passed any special command line arguments for normal
6656 operation should register a menu entry for those
6657 applications, so that users of the <tt>menu</tt> package
6658 will automatically get menu entries in their window
6659 managers, as well in shells like <tt>pdmenu</tt>.
6663 Menu entries should follow the current menu policy.
6667 The menu policy can be found in the <tt>menu-policy</tt>
6668 files in the <tt>debian-policy</tt> package.
6669 It is also available from the Debian web mirrors at
6670 <tt><url name="/doc/packaging-manuals/menu-policy/"
6671 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6675 Please also refer to the <em>Debian Menu System</em>
6676 documentation that comes with the <package>menu</package>
6677 package for information about how to register your
6683 <heading>Multimedia handlers</heading>
6686 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6687 is a mechanism for encoding files and data streams and
6688 providing meta-information about them, in particular their
6689 type (e.g. audio or video) and format (e.g. PNG, HTML,
6694 Registration of MIME type handlers allows programs like mail
6695 user agents and web browsers to invoke these handlers to
6696 view, edit or display MIME types they don't support directly.
6700 Packages which provide the ability to view/show/play,
6701 compose, edit or print MIME types should register themselves
6702 as such following the current MIME support policy.
6706 The MIME support policy can be found in the <tt>mime-policy</tt>
6707 files in the <tt>debian-policy</tt> package.
6708 It is also available from the Debian web mirrors at
6709 <tt><url name="/doc/packaging-manuals/mime-policy/"
6710 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6716 <heading>Keyboard configuration</heading>
6719 To achieve a consistent keyboard configuration so that all
6720 applications interpret a keyboard event the same way, all
6721 programs in the Debian distribution must be configured to
6722 comply with the following guidelines.
6726 The following keys must have the specified interpretations:
6729 <tag><tt><--</tt></tag>
6730 <item>delete the character to the left of the cursor</item>
6732 <tag><tt>Delete</tt></tag>
6733 <item>delete the character to the right of the cursor</item>
6735 <tag><tt>Control+H</tt></tag>
6736 <item>emacs: the help prefix</item>
6739 The interpretation of any keyboard events should be
6740 independent of the terminal that is used, be it a virtual
6741 console, an X terminal emulator, an rlogin/telnet session,
6746 The following list explains how the different programs
6747 should be set up to achieve this:
6753 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6757 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6761 X translations are set up to make
6762 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6763 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6764 is the vt220 escape code for the "delete character"
6765 key). This must be done by loading the X resources
6766 using <prgn>xrdb</prgn> on all local X displays, not
6767 using the application defaults, so that the
6768 translation resources used correspond to the
6769 <prgn>xmodmap</prgn> settings.
6773 The Linux console is configured to make
6774 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6775 generate <tt>ESC [ 3 ~</tt>.
6779 X applications are configured so that <tt><</tt>
6780 deletes left, and <tt>Delete</tt> deletes right. Motif
6781 applications already work like this.
6785 Terminals should have <tt>stty erase ^?</tt> .
6789 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6790 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6791 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6795 Emacs is programmed to map <tt>KB_Backspace</tt> or
6796 the <tt>stty erase</tt> character to
6797 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6798 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6799 <tt>^H</tt> to <tt>help</tt> as always.
6803 Other applications use the <tt>stty erase</tt>
6804 character and <tt>kdch1</tt> for the two delete keys,
6805 with ASCII DEL being "delete previous character" and
6806 <tt>kdch1</tt> being "delete character under
6814 This will solve the problem except for the following
6821 Some terminals have a <tt><--</tt> key that cannot
6822 be made to produce anything except <tt>^H</tt>. On
6823 these terminals Emacs help will be unavailable on
6824 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6825 character takes precedence in Emacs, and has been set
6826 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6827 available) can be used instead.
6831 Some operating systems use <tt>^H</tt> for <tt>stty
6832 erase</tt>. However, modern telnet versions and all
6833 rlogin versions propagate <tt>stty</tt> settings, and
6834 almost all UNIX versions honour <tt>stty erase</tt>.
6835 Where the <tt>stty</tt> settings are not propagated
6836 correctly, things can be made to work by using
6837 <tt>stty</tt> manually.
6841 Some systems (including previous Debian versions) use
6842 <prgn>xmodmap</prgn> to arrange for both
6843 <tt><--</tt> and <tt>Delete</tt> to generate
6844 <tt>KB_Delete</tt>. We can change the behavior of
6845 their X clients using the same X resources that we use
6846 to do it for our own clients, or configure our clients
6847 using their resources when things are the other way
6848 around. On displays configured like this
6849 <tt>Delete</tt> will not work, but <tt><--</tt>
6854 Some operating systems have different <tt>kdch1</tt>
6855 settings in their <tt>terminfo</tt> database for
6856 <tt>xterm</tt> and others. On these systems the
6857 <tt>Delete</tt> key will not work correctly when you
6858 log in from a system conforming to our policy, but
6859 <tt><--</tt> will.
6866 <heading>Environment variables</heading>
6869 A program must not depend on environment variables to get
6870 reasonable defaults. (That's because these environment
6871 variables would have to be set in a system-wide
6872 configuration file like <file>/etc/profile</file>, which is not
6873 supported by all shells.)
6877 If a program usually depends on environment variables for its
6878 configuration, the program should be changed to fall back to
6879 a reasonable default configuration if these environment
6880 variables are not present. If this cannot be done easily
6881 (e.g., if the source code of a non-free program is not
6882 available), the program must be replaced by a small
6883 "wrapper" shell script which sets the environment variables
6884 if they are not already defined, and calls the original program.
6888 Here is an example of a wrapper script for this purpose:
6890 <example compact="compact">
6892 BAR=${BAR:-/var/lib/fubar}
6894 exec /usr/lib/foo/foo "$@"
6899 Furthermore, as <file>/etc/profile</file> is a configuration
6900 file of the <prgn>base-files</prgn> package, other packages must
6901 not put any environment variables or other commands into that
6906 <sect id="doc-base">
6907 <heading>Registering Documents using doc-base</heading>
6910 The <package>doc-base</package> package implements a
6911 flexible mechanism for handling and presenting
6912 documentation. The recommended practice is for every Debian
6913 package that provides online documentation (other than just
6914 manual pages) to register these documents with
6915 <package>doc-base</package> by installing a
6916 <package>doc-base</package> control file via the
6917 <prgn/install-docs/ script at installation time and
6918 de-register the manuals again when the package is removed.
6921 Please refer to the documentation that comes with the
6922 <package>doc-base</package> package for information and
6931 <heading>Files</heading>
6934 <heading>Binaries</heading>
6937 Two different packages must not install programs with
6938 different functionality but with the same filenames. (The
6939 case of two programs having the same functionality but
6940 different implementations is handled via "alternatives" or
6941 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6942 <ref id="conflicts"> respectively.) If this case happens,
6943 one of the programs must be renamed. The maintainers should
6944 report this to the <tt>debian-devel</tt> mailing list and
6945 try to find a consensus about which program will have to be
6946 renamed. If a consensus cannot be reached, <em>both</em>
6947 programs must be renamed.
6951 By default, when a package is being built, any binaries
6952 created should include debugging information, as well as
6953 being compiled with optimization. You should also turn on
6954 as many reasonable compilation warnings as possible; this
6955 makes life easier for porters, who can then look at build
6956 logs for possible problems. For the C programming language,
6957 this means the following compilation parameters should be
6959 <example compact="compact">
6961 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6963 INSTALL = install -s # (or use strip on the files in debian/tmp)
6968 Note that by default all installed binaries should be stripped,
6969 either by using the <tt>-s</tt> flag to
6970 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6971 the binaries after they have been copied into
6972 <file>debian/tmp</file> but before the tree is made into a
6977 Although binaries in the build tree should be compiled with
6978 debugging information by default, it can often be difficult to
6979 debug programs if they are also subjected to compiler
6980 optimization. For this reason, it is recommended to support the
6981 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
6982 (see <ref id="debianrules-options">). This variable can contain
6983 several flags to change how a package is compiled and built.
6987 It is up to the package maintainer to decide what
6988 compilation options are best for the package. Certain
6989 binaries (such as computationally-intensive programs) will
6990 function better with certain flags (<tt>-O3</tt>, for
6991 example); feel free to use them. Please use good judgment
6992 here. Don't use flags for the sake of it; only use them
6993 if there is good reason to do so. Feel free to override
6994 the upstream author's ideas about which compilation
6995 options are best: they are often inappropriate for our
7001 <sect id="libraries">
7002 <heading>Libraries</heading>
7005 If the package is <strong>architecture: any</strong>, then
7006 the shared library compilation and linking flags must have
7007 <tt>-fPIC</tt>, or the package shall not build on some of
7008 the supported architectures<footnote>
7010 If you are using GCC, <tt>-fPIC</tt> produces code with
7011 relocatable position independent code, which is required for
7012 most architectures to create a shared library, with i386 and
7013 perhaps some others where non position independent code is
7014 permitted in a shared library.
7017 Position independent code may have a performance penalty,
7018 especially on <tt>i386</tt>. However, in most cases the
7019 speed penalty must be measured against the memory wasted on
7020 the few architectures where non position independent code is
7023 </footnote>. Any exception to this rule must be discussed on
7024 the mailing list <em>debian-devel@lists.debian.org</em>, and
7025 a rough consensus obtained. The reasons for not compiling
7026 with <tt>-fPIC</tt> flag must be recorded in the file
7027 <tt>README.Debian</tt>, and care must be taken to either
7028 restrict the architecture or arrange for <tt>-fPIC</tt> to
7029 be used on architectures where it is required.<footnote>
7031 Some of the reasons why this might be required is if the
7032 library contains hand crafted assembly code that is not
7033 relocatable, the speed penalty is excessive for compute
7034 intensive libs, and similar reasons.
7039 As to the static libraries, the common case is not to have
7040 relocatable code, since there is no benefit, unless in specific
7041 cases; therefore the static version must not be compiled
7042 with the <tt>-fPIC</tt> flag. Any exception to this rule
7043 should be discussed on the mailing list
7044 <em>debian-devel@lists.debian.org</em>, and the reasons for
7045 compiling with the <tt>-fPIC</tt> flag must be recorded in
7046 the file <tt>README.Debian</tt>. <footnote>
7048 Some of the reasons for linking static libraries with
7049 the <tt>-fPIC</tt> flag are if, for example, one needs a
7050 Perl API for a library that is under rapid development,
7051 and has an unstable API, so shared libraries are
7052 pointless at this phase of the library's development. In
7053 that case, since Perl needs a library with relocatable
7054 code, it may make sense to create a static library with
7055 relocatable code. Another reason cited is if you are
7056 distilling various libraries into a common shared
7057 library, like <tt>mklibs</tt> does in the Debian
7063 In other words, if both a shared and a static library is
7064 being built, each source unit (<tt>*.c</tt>, for example,
7065 for C files) will need to be compiled twice, for the normal
7069 You must specify the gcc option <tt>-D_REENTRANT</tt>
7070 when building a library (either static or shared) to make
7071 the library compatible with LinuxThreads.
7075 Although not enforced by the build tools, shared libraries
7076 must be linked against all libraries that they use symbols from
7077 in the same way that binaries are. This ensures the correct
7078 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
7079 system and guarantees that all libraries can be safely opened
7080 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
7081 option <tt>-Wl,-z,defs</tt> when building a shared library.
7082 Since this option enforces symbol resolution at build time,
7083 a missing library reference will be caught early as a fatal
7088 All installed shared libraries should be stripped with
7089 <example compact="compact">
7090 strip --strip-unneeded <var>your-lib</var>
7092 (The option <tt>--strip-unneeded</tt> makes
7093 <prgn>strip</prgn> remove only the symbols which aren't
7094 needed for relocation processing.) Shared libraries can
7095 function perfectly well when stripped, since the symbols for
7096 dynamic linking are in a separate part of the ELF object
7098 You might also want to use the options
7099 <tt>--remove-section=.comment</tt> and
7100 <tt>--remove-section=.note</tt> on both shared libraries
7101 and executables, and <tt>--strip-debug</tt> on static
7107 Note that under some circumstances it may be useful to
7108 install a shared library unstripped, for example when
7109 building a separate package to support debugging.
7113 Shared object files (often <file>.so</file> files) that are not
7114 public libraries, that is, they are not meant to be linked
7115 to by third party executables (binaries of other packages),
7116 should be installed in subdirectories of the
7117 <file>/usr/lib</file> directory. Such files are exempt from the
7118 rules that govern ordinary shared libraries, except that
7119 they must not be installed executable and should be
7121 A common example are the so-called "plug-ins",
7122 internal shared objects that are dynamically loaded by
7123 programs using <manref name="dlopen" section="3">.
7128 An ever increasing number of packages are using
7129 <prgn>libtool</prgn> to do their linking. The latest GNU
7130 libtools (>= 1.3a) can take advantage of the metadata in the
7131 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
7132 files). The main advantage of <prgn>libtool</prgn>'s
7133 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
7134 store and subsequently access metadata with respect to the
7135 libraries it builds. <prgn>libtool</prgn> will search for
7136 those files, which contain a lot of useful information about
7137 a library (such as library dependency information for static
7138 linking). Also, they're <em>essential</em> for programs
7139 using <tt>libltdl</tt>.<footnote>
7140 Although <prgn>libtool</prgn> is fully capable of
7141 linking against shared libraries which don't have
7142 <tt>.la</tt> files, as it is a mere shell script it can
7143 add considerably to the build time of a
7144 <prgn>libtool</prgn>-using package if that shell script
7145 has to derive all this information from first principles
7146 for each library every time it is linked. With the
7147 advent of <prgn>libtool</prgn> version 1.4 (and to a
7148 lesser extent <prgn>libtool</prgn> version 1.3), the
7149 <file>.la</file> files also store information about
7150 inter-library dependencies which cannot necessarily be
7151 derived after the <file>.la</file> file is deleted.
7156 Packages that use <prgn>libtool</prgn> to create shared
7157 libraries should include the <file>.la</file> files in the
7158 <tt>-dev</tt> package, unless the package relies on
7159 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
7160 the <tt>.la</tt> files must go in the run-time library
7165 You must make sure that you use only released versions of
7166 shared libraries to build your packages; otherwise other
7167 users will not be able to run your binaries
7168 properly. Producing source packages that depend on
7169 unreleased compilers is also usually a bad
7176 <heading>Shared libraries</heading>
7178 This section has moved to <ref id="sharedlibs">.
7184 <heading>Scripts</heading>
7187 All command scripts, including the package maintainer
7188 scripts inside the package and used by <prgn>dpkg</prgn>,
7189 should have a <tt>#!</tt> line naming the shell to be used
7194 In the case of Perl scripts this should be
7195 <tt>#!/usr/bin/perl</tt>.
7199 When scripts are installed into a directory in the system
7200 PATH, the script name should not include an extension such
7201 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7202 language currently used to implement it.
7205 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
7206 should almost certainly start with <tt>set -e</tt> so that
7207 errors are detected. Every script should use
7208 <tt>set -e</tt> or check the exit status of <em>every</em>
7213 Scripts may assume that <file>/bin/sh</file> implements the
7214 SUSv3 Shell Command Language<footnote>
7215 Single UNIX Specification, version 3, which is also IEEE
7216 1003.1-2004 (POSIX), and is available on the World Wide Web
7217 from <url id="http://www.unix.org/version3/online.html"
7218 name="The Open Group"> after free
7219 registration.</footnote>
7220 plus the following additional features not mandated by
7222 These features are in widespread use in the Linux community
7223 and are implemented in all of bash, dash, and ksh, the most
7224 common shells users may wish to use as <file>/bin/sh</file>.
7227 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7228 must not generate a newline.</item>
7229 <item><tt>test</tt>, if implemented as a shell built-in, must
7230 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7232 <item><tt>local</tt> to create a scoped variable must be
7233 supported, including listing multiple variables in a single
7234 local command and assigning a value to a variable at the
7235 same time as localizing it. <tt>local</tt> may or
7236 may not preserve the variable value from an outer scope if
7237 no assignment is present. Uses such as:
7241 # ... use a, b, c, d ...
7244 must be supported and must set the value of <tt>c</tt> to
7248 If a shell script requires non-SUSv3 features from the shell
7249 interpreter other than those listed above, the appropriate shell
7250 must be specified in the first line of the script (e.g.,
7251 <tt>#!/bin/bash</tt>) and the package must depend on the package
7252 providing the shell (unless the shell package is marked
7253 "Essential", as in the case of <prgn>bash</prgn>).
7257 You may wish to restrict your script to SUSv3 features plus the
7258 above set when possible so that it may use <file>/bin/sh</file>
7259 as its interpreter. If your script works with <prgn>dash</prgn>
7260 (originally called <prgn>ash</prgn>), it probably complies with
7261 the above requirements, but if you are in doubt, use
7262 <file>/bin/bash</file>.
7266 Perl scripts should check for errors when making any
7267 system calls, including <tt>open</tt>, <tt>print</tt>,
7268 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7272 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7273 scripting languages. See <em>Csh Programming Considered
7274 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7275 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7276 If an upstream package comes with <prgn>csh</prgn> scripts
7277 then you must make sure that they start with
7278 <tt>#!/bin/csh</tt> and make your package depend on the
7279 <prgn>c-shell</prgn> virtual package.
7283 Any scripts which create files in world-writeable
7284 directories (e.g., in <file>/tmp</file>) must use a
7285 mechanism which will fail atomically if a file with the same
7286 name already exists.
7290 The Debian base system provides the <prgn>tempfile</prgn>
7291 and <prgn>mktemp</prgn> utilities for use by scripts for
7298 <heading>Symbolic links</heading>
7301 In general, symbolic links within a top-level directory
7302 should be relative, and symbolic links pointing from one
7303 top-level directory into another should be absolute. (A
7304 top-level directory is a sub-directory of the root
7305 directory <file>/</file>.)
7309 In addition, symbolic links should be specified as short as
7310 possible, i.e., link targets like <file>foo/../bar</file> are
7315 Note that when creating a relative link using
7316 <prgn>ln</prgn> it is not necessary for the target of the
7317 link to exist relative to the working directory you're
7318 running <prgn>ln</prgn> from, nor is it necessary to change
7319 directory to the directory where the link is to be made.
7320 Simply include the string that should appear as the target
7321 of the link (this will be a pathname relative to the
7322 directory in which the link resides) as the first argument
7327 For example, in your <prgn>Makefile</prgn> or
7328 <file>debian/rules</file>, you can do things like:
7329 <example compact="compact">
7330 ln -fs gcc $(prefix)/bin/cc
7331 ln -fs gcc debian/tmp/usr/bin/cc
7332 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7333 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7338 A symbolic link pointing to a compressed file should always
7339 have the same file extension as the referenced file. (For
7340 example, if a file <file>foo.gz</file> is referenced by a
7341 symbolic link, the filename of the link has to end with
7342 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7347 <heading>Device files</heading>
7350 Packages must not include device files or named pipes in the
7355 If a package needs any special device files that are not
7356 included in the base system, it must call
7357 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7358 after notifying the user<footnote>
7359 This notification could be done via a (low-priority)
7360 debconf message, or an echo (printf) statement.
7365 Packages must not remove any device files in the
7366 <prgn>postrm</prgn> or any other script. This is left to the
7367 system administrator.
7371 Debian uses the serial devices
7372 <file>/dev/ttyS*</file>. Programs using the old
7373 <file>/dev/cu*</file> devices should be changed to use
7374 <file>/dev/ttyS*</file>.
7378 Named pipes needed by the package must be created in
7379 the <prgn>postinst</prgn> script<footnote>
7380 It's better to use <prgn>mkfifo</prgn> rather
7381 than <prgn>mknod</prgn> to create named pipes so that
7382 automated checks for packages incorrectly creating device
7383 files with <prgn>mknod</prgn> won't have false positives.
7384 </footnote> and removed in
7385 the <prgn>prerm</prgn> or <prgn>postrm</prgn> script as
7390 <sect id="config-files">
7391 <heading>Configuration files</heading>
7394 <heading>Definitions</heading>
7398 <tag>configuration file</tag>
7400 A file that affects the operation of a program, or
7401 provides site- or host-specific information, or
7402 otherwise customizes the behavior of a program.
7403 Typically, configuration files are intended to be
7404 modified by the system administrator (if needed or
7405 desired) to conform to local policy or to provide
7406 more useful site-specific behavior.
7409 <tag><tt>conffile</tt></tag>
7411 A file listed in a package's <tt>conffiles</tt>
7412 file, and is treated specially by <prgn>dpkg</prgn>
7413 (see <ref id="configdetails">).
7419 The distinction between these two is important; they are
7420 not interchangeable concepts. Almost all
7421 <tt>conffile</tt>s are configuration files, but many
7422 configuration files are not <tt>conffiles</tt>.
7426 As noted elsewhere, <file>/etc/init.d</file> scripts,
7427 <file>/etc/default</file> files, scripts installed in
7428 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7429 configuration installed in <file>/etc/cron.d</file> must be
7430 treated as configuration files. In general, any script that
7431 embeds configuration information is de-facto a configuration
7432 file and should be treated as such.
7437 <heading>Location</heading>
7440 Any configuration files created or used by your package
7441 must reside in <file>/etc</file>. If there are several,
7442 consider creating a subdirectory of <file>/etc</file>
7443 named after your package.
7447 If your package creates or uses configuration files
7448 outside of <file>/etc</file>, and it is not feasible to modify
7449 the package to use <file>/etc</file> directly, put the files
7450 in <file>/etc</file> and create symbolic links to those files
7451 from the location that the package requires.
7456 <heading>Behavior</heading>
7459 Configuration file handling must conform to the following
7461 <list compact="compact">
7463 local changes must be preserved during a package
7467 configuration files must be preserved when the
7468 package is removed, and only deleted when the
7475 The easy way to achieve this behavior is to make the
7476 configuration file a <tt>conffile</tt>. This is
7477 appropriate only if it is possible to distribute a default
7478 version that will work for most installations, although
7479 some system administrators may choose to modify it. This
7480 implies that the default version will be part of the
7481 package distribution, and must not be modified by the
7482 maintainer scripts during installation (or at any other
7487 In order to ensure that local changes are preserved
7488 correctly, no package may contain or make hard links to
7489 conffiles.<footnote>
7490 Rationale: There are two problems with hard links.
7491 The first is that some editors break the link while
7492 editing one of the files, so that the two files may
7493 unwittingly become unlinked and different. The second
7494 is that <prgn>dpkg</prgn> might break the hard link
7495 while upgrading <tt>conffile</tt>s.
7500 The other way to do it is via the maintainer scripts. In
7501 this case, the configuration file must not be listed as a
7502 <tt>conffile</tt> and must not be part of the package
7503 distribution. If the existence of a file is required for
7504 the package to be sensibly configured it is the
7505 responsibility of the package maintainer to provide
7506 maintainer scripts which correctly create, update and
7507 maintain the file and remove it on purge. (See <ref
7508 id="maintainerscripts"> for more information.) These
7509 scripts must be idempotent (i.e., must work correctly if
7510 <prgn>dpkg</prgn> needs to re-run them due to errors
7511 during installation or removal), must cope with all the
7512 variety of ways <prgn>dpkg</prgn> can call maintainer
7513 scripts, must not overwrite or otherwise mangle the user's
7514 configuration without asking, must not ask unnecessary
7515 questions (particularly during upgrades), and must
7516 otherwise be good citizens.
7520 The scripts are not required to configure every possible
7521 option for the package, but only those necessary to get
7522 the package running on a given system. Ideally the
7523 sysadmin should not have to do any configuration other
7524 than that done (semi-)automatically by the
7525 <prgn>postinst</prgn> script.
7529 A common practice is to create a script called
7530 <file><var>package</var>-configure</file> and have the
7531 package's <prgn>postinst</prgn> call it if and only if the
7532 configuration file does not already exist. In certain
7533 cases it is useful for there to be an example or template
7534 file which the maintainer scripts use. Such files should
7535 be in <file>/usr/share/<var>package</var></file> or
7536 <file>/usr/lib/<var>package</var></file> (depending on whether
7537 they are architecture-independent or not). There should
7538 be symbolic links to them from
7539 <file>/usr/share/doc/<var>package</var>/examples</file> if
7540 they are examples, and should be perfectly ordinary
7541 <prgn>dpkg</prgn>-handled files (<em>not</em>
7542 configuration files).
7546 These two styles of configuration file handling must
7547 not be mixed, for that way lies madness:
7548 <prgn>dpkg</prgn> will ask about overwriting the file
7549 every time the package is upgraded.
7554 <heading>Sharing configuration files</heading>
7557 Packages which specify the same file as a
7558 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7559 with each other. (This is an instance of the general rule
7560 about not sharing files. Note that neither alternatives
7561 nor diversions are likely to be appropriate in this case;
7562 in particular, <prgn>dpkg</prgn> does not handle diverted
7563 <tt>conffile</tt>s well.)
7567 The maintainer scripts must not alter a <tt>conffile</tt>
7568 of <em>any</em> package, including the one the scripts
7573 If two or more packages use the same configuration file
7574 and it is reasonable for both to be installed at the same
7575 time, one of these packages must be defined as
7576 <em>owner</em> of the configuration file, i.e., it will be
7577 the package which handles that file as a configuration
7578 file. Other packages that use the configuration file must
7579 depend on the owning package if they require the
7580 configuration file to operate. If the other package will
7581 use the configuration file if present, but is capable of
7582 operating without it, no dependency need be declared.
7586 If it is desirable for two or more related packages to
7587 share a configuration file <em>and</em> for all of the
7588 related packages to be able to modify that configuration
7589 file, then the following should be done:
7590 <enumlist compact="compact">
7592 One of the related packages (the "owning" package)
7593 will manage the configuration file with maintainer
7594 scripts as described in the previous section.
7597 The owning package should also provide a program
7598 that the other packages may use to modify the
7602 The related packages must use the provided program
7603 to make any desired modifications to the
7604 configuration file. They should either depend on
7605 the core package to guarantee that the configuration
7606 modifier program is available or accept gracefully
7607 that they cannot modify the configuration file if it
7608 is not. (This is in addition to the fact that the
7609 configuration file may not even be present in the
7616 Sometimes it's appropriate to create a new package which
7617 provides the basic infrastructure for the other packages
7618 and which manages the shared configuration files. (The
7619 <tt>sgml-base</tt> package is a good example.)
7624 <heading>User configuration files ("dotfiles")</heading>
7627 The files in <file>/etc/skel</file> will automatically be
7628 copied into new user accounts by <prgn>adduser</prgn>.
7629 No other program should reference the files in
7630 <file>/etc/skel</file>.
7634 Therefore, if a program needs a dotfile to exist in
7635 advance in <file>$HOME</file> to work sensibly, that dotfile
7636 should be installed in <file>/etc/skel</file> and treated as a
7641 However, programs that require dotfiles in order to
7642 operate sensibly are a bad thing, unless they do create
7643 the dotfiles themselves automatically.
7647 Furthermore, programs should be configured by the Debian
7648 default installation to behave as closely to the upstream
7649 default behavior as possible.
7653 Therefore, if a program in a Debian package needs to be
7654 configured in some way in order to operate sensibly, that
7655 should be done using a site-wide configuration file placed
7656 in <file>/etc</file>. Only if the program doesn't support a
7657 site-wide default configuration and the package maintainer
7658 doesn't have time to add it may a default per-user file be
7659 placed in <file>/etc/skel</file>.
7663 <file>/etc/skel</file> should be as empty as we can make it.
7664 This is particularly true because there is no easy (or
7665 necessarily desirable) mechanism for ensuring that the
7666 appropriate dotfiles are copied into the accounts of
7667 existing users when a package is installed.
7673 <heading>Log files</heading>
7675 Log files should usually be named
7676 <file>/var/log/<var>package</var>.log</file>. If you have many
7677 log files, or need a separate directory for permission
7678 reasons (<file>/var/log</file> is writable only by
7679 <file>root</file>), you should usually create a directory named
7680 <file>/var/log/<var>package</var></file> and place your log
7685 Log files must be rotated occasionally so that they don't
7686 grow indefinitely; the best way to do this is to drop a log
7687 rotation configuration file into the directory
7688 <file>/etc/logrotate.d</file> and use the facilities provided by
7689 logrotate.<footnote>
7691 The traditional approach to log files has been to set up
7692 <em>ad hoc</em> log rotation schemes using simple shell
7693 scripts and cron. While this approach is highly
7694 customizable, it requires quite a lot of sysadmin work.
7695 Even though the original Debian system helped a little
7696 by automatically installing a system which can be used
7697 as a template, this was deemed not enough.
7701 The use of <prgn>logrotate</prgn>, a program developed
7702 by Red Hat, is better, as it centralizes log management.
7703 It has both a configuration file
7704 (<file>/etc/logrotate.conf</file>) and a directory where
7705 packages can drop their individual log rotation
7706 configurations (<file>/etc/logrotate.d</file>).
7709 Here is a good example for a logrotate config
7710 file (for more information see <manref name="logrotate"
7712 <example compact="compact">
7713 /var/log/foo/*.log {
7718 /etc/init.d/foo force-reload
7722 This rotates all files under <file>/var/log/foo</file>, saves 12
7723 compressed generations, and forces the daemon to reload its
7724 configuration information after the log rotation.
7728 Log files should be removed when the package is
7729 purged (but not when it is only removed). This should be
7730 done by the <prgn>postrm</prgn> script when it is called
7731 with the argument <tt>purge</tt> (see <ref
7732 id="removedetails">).
7737 <heading>Permissions and owners</heading>
7740 The rules in this section are guidelines for general use.
7741 If necessary you may deviate from the details below.
7742 However, if you do so you must make sure that what is done
7743 is secure and you should try to be as consistent as possible
7744 with the rest of the system. You should probably also
7745 discuss it on <prgn>debian-devel</prgn> first.
7749 Files should be owned by <tt>root:root</tt>, and made
7750 writable only by the owner and universally readable (and
7751 executable, if appropriate), that is mode 644 or 755.
7755 Directories should be mode 755 or (for group-writability)
7756 mode 2775. The ownership of the directory should be
7757 consistent with its mode: if a directory is mode 2775, it
7758 should be owned by the group that needs write access to
7761 When a package is upgraded, and the owner or permissions
7762 of a file included in the package has changed, dpkg
7763 arranges for the ownership and permissions to be
7764 correctly set upon installation. However, this does not
7765 extend to directories; the permissions and ownership of
7766 directories already on the system does not change on
7767 install or upgrade of packages. This makes sense, since
7768 otherwise common directories like <tt>/usr</tt> would
7769 always be in flux. To correctly change permissions of a
7770 directory the package owns, explicit action is required,
7771 usually in the <tt>postinst</tt> script. Care must be
7772 taken to handle downgrades as well, in that case.
7779 Setuid and setgid executables should be mode 4755 or 2755
7780 respectively, and owned by the appropriate user or group.
7781 They should not be made unreadable (modes like 4711 or
7782 2711 or even 4111); doing so achieves no extra security,
7783 because anyone can find the binary in the freely available
7784 Debian package; it is merely inconvenient. For the same
7785 reason you should not restrict read or execute permissions
7786 on non-set-id executables.
7790 Some setuid programs need to be restricted to particular
7791 sets of users, using file permissions. In this case they
7792 should be owned by the uid to which they are set-id, and by
7793 the group which should be allowed to execute them. They
7794 should have mode 4754; again there is no point in making
7795 them unreadable to those users who must not be allowed to
7800 It is possible to arrange that the system administrator can
7801 reconfigure the package to correspond to their local
7802 security policy by changing the permissions on a binary:
7803 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7804 described below.<footnote>
7805 Ordinary files installed by <prgn>dpkg</prgn> (as
7806 opposed to <tt>conffile</tt>s and other similar objects)
7807 normally have their permissions reset to the distributed
7808 permissions when the package is reinstalled. However,
7809 the use of <prgn>dpkg-statoverride</prgn> overrides this
7812 Another method you should consider is to create a group for
7813 people allowed to use the program(s) and make any setuid
7814 executables executable only by that group.
7818 If you need to create a new user or group for your package
7819 there are two possibilities. Firstly, you may need to
7820 make some files in the binary package be owned by this
7821 user or group, or you may need to compile the user or
7822 group id (rather than just the name) into the binary
7823 (though this latter should be avoided if possible, as in
7824 this case you need a statically allocated id).</p>
7827 If you need a statically allocated id, you must ask for a
7828 user or group id from the <tt>base-passwd</tt> maintainer,
7829 and must not release the package until you have been
7830 allocated one. Once you have been allocated one you must
7831 either make the package depend on a version of the
7832 <tt>base-passwd</tt> package with the id present in
7833 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7834 your package to create the user or group itself with the
7835 correct id (using <tt>adduser</tt>) in its
7836 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7837 the <prgn>postinst</prgn> is to be preferred if it is
7838 possible, otherwise a pre-dependency will be needed on the
7839 <tt>adduser</tt> package.)
7843 On the other hand, the program might be able to determine
7844 the uid or gid from the user or group name at runtime, so
7845 that a dynamically allocated id can be used. In this case
7846 you should choose an appropriate user or group name,
7847 discussing this on <prgn>debian-devel</prgn> and checking
7848 with the <package/base-passwd/ maintainer that it is unique and that
7849 they do not wish you to use a statically allocated id
7850 instead. When this has been checked you must arrange for
7851 your package to create the user or group if necessary using
7852 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7853 <prgn>postinst</prgn> script (again, the latter is to be
7854 preferred if it is possible).
7858 Note that changing the numeric value of an id associated
7859 with a name is very difficult, and involves searching the
7860 file system for all appropriate files. You need to think
7861 carefully whether a static or dynamic id is required, since
7862 changing your mind later will cause problems.
7865 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7867 This section is not intended as policy, but as a
7868 description of the use of <prgn>dpkg-statoverride</prgn>.
7872 If a system administrator wishes to have a file (or
7873 directory or other such thing) installed with owner and
7874 permissions different from those in the distributed Debian
7875 package, they can use the <prgn>dpkg-statoverride</prgn>
7876 program to instruct <prgn>dpkg</prgn> to use the different
7877 settings every time the file is installed. Thus the
7878 package maintainer should distribute the files with their
7879 normal permissions, and leave it for the system
7880 administrator to make any desired changes. For example, a
7881 daemon which is normally required to be setuid root, but
7882 in certain situations could be used without being setuid,
7883 should be installed setuid in the <tt>.deb</tt>. Then the
7884 local system administrator can change this if they wish.
7885 If there are two standard ways of doing it, the package
7886 maintainer can use <tt>debconf</tt> to find out the
7887 preference, and call <prgn>dpkg-statoverride</prgn> in the
7888 maintainer script if necessary to accommodate the system
7889 administrator's choice. Care must be taken during
7890 upgrades to not override an existing setting.
7894 Given the above, <prgn>dpkg-statoverride</prgn> is
7895 essentially a tool for system administrators and would not
7896 normally be needed in the maintainer scripts. There is
7897 one type of situation, though, where calls to
7898 <prgn>dpkg-statoverride</prgn> would be needed in the
7899 maintainer scripts, and that involves packages which use
7900 dynamically allocated user or group ids. In such a
7901 situation, something like the following idiom can be very
7902 helpful in the package's <prgn>postinst</prgn>, where
7903 <tt>sysuser</tt> is a dynamically allocated id:
7905 for i in /usr/bin/foo /usr/sbin/bar
7907 # only do something when no setting exists
7908 if ! dpkg-statoverride --list $i >/dev/null 2>&1
7910 #include: debconf processing, question about foo and bar
7911 if [ "$RET" = "true" ] ; then
7912 dpkg-statoverride --update --add sysuser root 4755 $i
7917 The corresponding code to remove the override when the package
7920 for i in /usr/bin/foo /usr/sbin/bar
7922 if dpkg-statoverride --list $i >/dev/null 2>&1
7924 dpkg-statoverride --remove $i
7934 <chapt id="customized-programs">
7935 <heading>Customized programs</heading>
7937 <sect id="arch-spec">
7938 <heading>Architecture specification strings</heading>
7941 If a program needs to specify an <em>architecture specification
7942 string</em> in some place, it should select one of the
7943 strings provided by <tt>dpkg-architecture -L</tt>. The
7944 strings are in the format
7945 <tt><var>os</var>-<var>arch</var></tt>, though the OS part
7946 is sometimes elided, as when the OS is Linux.<footnote>
7947 <p>Currently, the strings are:
7948 i386 ia64 alpha amd64 armeb arm hppa m32r m68k mips
7949 mipsel powerpc ppc64 s390 s390x sh3 sh3eb sh4 sh4eb
7950 sparc darwin-i386 darwin-ia64 darwin-alpha darwin-amd64
7951 darwin-armeb darwin-arm darwin-hppa darwin-m32r
7952 darwin-m68k darwin-mips darwin-mipsel darwin-powerpc
7953 darwin-ppc64 darwin-s390 darwin-s390x darwin-sh3
7954 darwin-sh3eb darwin-sh4 darwin-sh4eb darwin-sparc
7955 freebsd-i386 freebsd-ia64 freebsd-alpha freebsd-amd64
7956 freebsd-armeb freebsd-arm freebsd-hppa freebsd-m32r
7957 freebsd-m68k freebsd-mips freebsd-mipsel freebsd-powerpc
7958 freebsd-ppc64 freebsd-s390 freebsd-s390x freebsd-sh3
7959 freebsd-sh3eb freebsd-sh4 freebsd-sh4eb freebsd-sparc
7960 kfreebsd-i386 kfreebsd-ia64 kfreebsd-alpha
7961 kfreebsd-amd64 kfreebsd-armeb kfreebsd-arm kfreebsd-hppa
7962 kfreebsd-m32r kfreebsd-m68k kfreebsd-mips
7963 kfreebsd-mipsel kfreebsd-powerpc kfreebsd-ppc64
7964 kfreebsd-s390 kfreebsd-s390x kfreebsd-sh3 kfreebsd-sh3eb
7965 kfreebsd-sh4 kfreebsd-sh4eb kfreebsd-sparc knetbsd-i386
7966 knetbsd-ia64 knetbsd-alpha knetbsd-amd64 knetbsd-armeb
7967 knetbsd-arm knetbsd-hppa knetbsd-m32r knetbsd-m68k
7968 knetbsd-mips knetbsd-mipsel knetbsd-powerpc
7969 knetbsd-ppc64 knetbsd-s390 knetbsd-s390x knetbsd-sh3
7970 knetbsd-sh3eb knetbsd-sh4 knetbsd-sh4eb knetbsd-sparc
7971 netbsd-i386 netbsd-ia64 netbsd-alpha netbsd-amd64
7972 netbsd-armeb netbsd-arm netbsd-hppa netbsd-m32r
7973 netbsd-m68k netbsd-mips netbsd-mipsel netbsd-powerpc
7974 netbsd-ppc64 netbsd-s390 netbsd-s390x netbsd-sh3
7975 netbsd-sh3eb netbsd-sh4 netbsd-sh4eb netbsd-sparc
7976 openbsd-i386 openbsd-ia64 openbsd-alpha openbsd-amd64
7977 openbsd-armeb openbsd-arm openbsd-hppa openbsd-m32r
7978 openbsd-m68k openbsd-mips openbsd-mipsel openbsd-powerpc
7979 openbsd-ppc64 openbsd-s390 openbsd-s390x openbsd-sh3
7980 openbsd-sh3eb openbsd-sh4 openbsd-sh4eb openbsd-sparc
7981 hurd-i386 hurd-ia64 hurd-alpha hurd-amd64 hurd-armeb
7982 hurd-arm hurd-hppa hurd-m32r hurd-m68k hurd-mips
7983 hurd-mipsel hurd-powerpc hurd-ppc64 hurd-s390 hurd-s390x
7984 hurd-sh3 hurd-sh3eb hurd-sh4 hurd-sh4eb hurd-sparc
7990 Note that we don't want to use
7991 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7992 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7993 since this would make our programs incompatible with other
7994 Linux distributions. We also don't use something like
7995 <tt><var>arch</var>-unknown-linux</tt>, since the
7996 <tt>unknown</tt> does not look very good.
8000 <sect id="arch-wildcard-spec">
8001 <heading>Architecture Wildcards</heading>
8004 A package may specify an architecture wildcard. Architecture
8005 wildcards are in the format <tt>any</tt> (which matches every
8006 architecture), <tt><var>os</var></tt>-any, or
8007 any-<tt><var>cpu</var></tt>. <footnote>
8008 Internally, the package system normalizes the GNU triplets and
8009 the Debian arches into Debian arch triplets (which are kind of
8010 inverted GNU triplets), with the first component of the
8011 triplet representing the libc and ABI in use. When matching
8012 two Debian arch triplets, whenever an <var>any</var> is found
8013 it matches with anything on the other side, like in:
8015 gnu-linux-i386 is matched by gnu-linux-any
8016 gnu-kfreebsd-amd64 is matched by any-any-amd64
8018 And, for example, <var>any</var> is normalized to
8019 <var>any-any-any</var>.
8025 <heading>Daemons</heading>
8028 The configuration files <file>/etc/services</file>,
8029 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
8030 by the <prgn>netbase</prgn> package and must not be modified
8035 If a package requires a new entry in one of these files, the
8036 maintainer should get in contact with the
8037 <prgn>netbase</prgn> maintainer, who will add the entries
8038 and release a new version of the <prgn>netbase</prgn>
8043 The configuration file <file>/etc/inetd.conf</file> must not be
8044 modified by the package's scripts except via the
8045 <prgn>update-inetd</prgn> script or the
8046 <file>DebianNet.pm</file> Perl module. See their documentation
8047 for details on how to add entries.
8051 If a package wants to install an example entry into
8052 <file>/etc/inetd.conf</file>, the entry must be preceded with
8053 exactly one hash character (<tt>#</tt>). Such lines are
8054 treated as "commented out by user" by the
8055 <prgn>update-inetd</prgn> script and are not changed or
8056 activated during package updates.
8061 <heading>Using pseudo-ttys and modifying wtmp, utmp and
8065 Some programs need to create pseudo-ttys. This should be done
8066 using Unix98 ptys if the C library supports it. The resulting
8067 program must not be installed setuid root, unless that
8068 is required for other functionality.
8072 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
8073 <file>/var/log/lastlog</file> must be installed writable by
8074 group <tt>utmp</tt>. Programs which need to modify those
8075 files must be installed setgid <tt>utmp</tt>.
8080 <heading>Editors and pagers</heading>
8083 Some programs have the ability to launch an editor or pager
8084 program to edit or display a text document. Since there are
8085 lots of different editors and pagers available in the Debian
8086 distribution, the system administrator and each user should
8087 have the possibility to choose their preferred editor and
8092 In addition, every program should choose a good default
8093 editor/pager if none is selected by the user or system
8098 Thus, every program that launches an editor or pager must
8099 use the EDITOR or PAGER environment variable to determine
8100 the editor or pager the user wishes to use. If these
8101 variables are not set, the programs <file>/usr/bin/editor</file>
8102 and <file>/usr/bin/pager</file> should be used, respectively.
8106 These two files are managed through the <prgn>dpkg</prgn>
8107 "alternatives" mechanism. Thus every package providing an
8108 editor or pager must call the
8109 <prgn>update-alternatives</prgn> script to register these
8114 If it is very hard to adapt a program to make use of the
8115 EDITOR or PAGER variables, that program may be configured to
8116 use <file>/usr/bin/sensible-editor</file> and
8117 <file>/usr/bin/sensible-pager</file> as the editor or pager
8118 program respectively. These are two scripts provided in the
8119 <package>sensible-utils</package> package that check the EDITOR
8120 and PAGER variables and launch the appropriate program, and fall
8121 back to <file>/usr/bin/editor</file>
8122 and <file>/usr/bin/pager</file> if the variable is not set.
8126 A program may also use the VISUAL environment variable to
8127 determine the user's choice of editor. If it exists, it
8128 should take precedence over EDITOR. This is in fact what
8129 <file>/usr/bin/sensible-editor</file> does.
8133 It is not required for a package to depend on
8134 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
8135 package to provide such virtual packages.<footnote>
8136 The Debian base system already provides an editor and a
8142 <sect id="web-appl">
8143 <heading>Web servers and applications</heading>
8146 This section describes the locations and URLs that should
8147 be used by all web servers and web applications in the
8154 Cgi-bin executable files are installed in the
8156 <example compact="compact">
8157 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
8159 and should be referred to as
8160 <example compact="compact">
8161 http://localhost/cgi-bin/<var>cgi-bin-name</var>
8167 <p>Access to HTML documents</p>
8170 HTML documents for a package are stored in
8171 <file>/usr/share/doc/<var>package</var></file>
8172 and can be referred to as
8173 <example compact="compact">
8174 http://localhost/doc/<var>package</var>/<var>filename</var>
8179 The web server should restrict access to the document
8180 tree so that only clients on the same host can read
8181 the documents. If the web server does not support such
8182 access controls, then it should not provide access at
8183 all, or ask about providing access during installation.
8188 <p>Access to images</p>
8190 It is recommended that images for a package be stored
8191 in <tt>/usr/share/images/<var>package</var></tt> and
8192 may be referred to through an alias <tt>/images/</tt>
8195 http://localhost/images/<package>/<filename>
8202 <p>Web Document Root</p>
8205 Web Applications should try to avoid storing files in
8206 the Web Document Root. Instead they should use the
8207 /usr/share/doc/<var>package</var> directory for
8208 documents and register the Web Application via the
8209 <package>doc-base</package> package. If access to the
8210 web document root is unavoidable then use
8211 <example compact="compact">
8214 as the Document Root. This might be just a symbolic
8215 link to the location where the system administrator
8216 has put the real document root.
8219 <item><p>Providing httpd and/or httpd-cgi</p>
8221 All web servers should provide the virtual package
8222 <tt>httpd</tt>. If a web server has CGI support it should
8223 provide <tt>httpd-cgi</tt> additionally.
8226 All web applications which do not contain CGI scripts should
8227 depend on <tt>httpd</tt>, all those web applications which
8228 <tt>do</tt> contain CGI scripts, should depend on
8236 <sect id="mail-transport-agents">
8237 <heading>Mail transport, delivery and user agents</heading>
8240 Debian packages which process electronic mail, whether mail
8241 user agents (MUAs) or mail transport agents (MTAs), must
8242 ensure that they are compatible with the configuration
8243 decisions below. Failure to do this may result in lost
8244 mail, broken <tt>From:</tt> lines, and other serious brain
8249 The mail spool is <file>/var/mail</file> and the interface to
8250 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8251 the FHS). On older systems, the mail spool may be
8252 physically located in <file>/var/spool/mail</file>, but all
8253 access to the mail spool should be via the
8254 <file>/var/mail</file> symlink. The mail spool is part of the
8255 base system and not part of the MTA package.
8259 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8260 programs (such as IMAP daemons) must lock the mailbox in an
8261 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8262 be combined with dot locking. To avoid deadlocks, a program
8263 should use <tt>fcntl()</tt> first and dot locking after
8264 this, or alternatively implement the two locking methods in
8265 a non blocking way<footnote>
8266 If it is not possible to establish both locks, the
8267 system shouldn't wait for the second lock to be
8268 established, but remove the first lock, wait a (random)
8269 time, and start over locking again.
8270 </footnote>. Using the functions <tt>maillock</tt> and
8271 <tt>mailunlock</tt> provided by the
8272 <tt>liblockfile*</tt><footnote>
8273 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8274 to use these functions.
8275 </footnote> packages is the recommended way to realize this.
8279 Mailboxes are generally either mode 600 and owned by
8280 <var>user</var> or mode 660 and owned by
8281 <tt><var>user</var>:mail</tt><footnote>
8282 There are two traditional permission schemes for mail spools:
8283 mode 600 with all mail delivery done by processes running as
8284 the destination user, or mode 660 and owned by group mail with
8285 mail delivery done by a process running as a system user in
8286 group mail. Historically, Debian required mode 660 mail
8287 spools to enable the latter model, but that model has become
8288 increasingly uncommon and the principle of least privilege
8289 indicates that mail systems that use the first model should
8290 use permissions of 600. If delivery to programs is permitted,
8291 it's easier to keep the mail system secure if the delivery
8292 agent runs as the destination user. Debian Policy therefore
8293 permits either scheme.
8294 </footnote>. The local system administrator may choose a
8295 different permission scheme; packages should not make
8296 assumptions about the permission and ownership of mailboxes
8297 unless required (such as when creating a new mailbox). A MUA
8298 may remove a mailbox (unless it has nonstandard permissions) in
8299 which case the MTA or another MUA must recreate it if needed.
8303 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8304 be setgid mail to do the locking mentioned above (and
8305 must obviously avoid accessing other users' mailboxes
8306 using this privilege).</p>
8309 <file>/etc/aliases</file> is the source file for the system mail
8310 aliases (e.g., postmaster, usenet, etc.), it is the one
8311 which the sysadmin and <prgn>postinst</prgn> scripts may
8312 edit. After <file>/etc/aliases</file> is edited the program or
8313 human editing it must call <prgn>newaliases</prgn>. All MTA
8314 packages must come with a <prgn>newaliases</prgn> program,
8315 even if it does nothing, but older MTA packages did not do
8316 this so programs should not fail if <prgn>newaliases</prgn>
8317 cannot be found. Note that because of this, all MTA
8318 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8319 <tt>Replaces: mail-transport-agent</tt> control file
8324 The convention of writing <tt>forward to
8325 <var>address</var></tt> in the mailbox itself is not
8326 supported. Use a <tt>.forward</tt> file instead.</p>
8329 The <prgn>rmail</prgn> program used by UUCP
8330 for incoming mail should be <file>/usr/sbin/rmail</file>.
8331 Likewise, <prgn>rsmtp</prgn>, for receiving
8332 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8336 If your package needs to know what hostname to use on (for
8337 example) outgoing news and mail messages which are generated
8338 locally, you should use the file <file>/etc/mailname</file>. It
8339 will contain the portion after the username and <tt>@</tt>
8340 (at) sign for email addresses of users on the machine
8341 (followed by a newline).
8345 Such a package should check for the existence of this file
8346 when it is being configured. If it exists, it should be
8347 used without comment, although an MTA's configuration script
8348 may wish to prompt the user even if it finds that this file
8349 exists. If the file does not exist, the package should
8350 prompt the user for the value (preferably using
8351 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8352 as well as using it in the package's configuration. The
8353 prompt should make it clear that the name will not just be
8354 used by that package. For example, in this situation the
8355 <tt>inn</tt> package could say something like:
8356 <example compact="compact">
8357 Please enter the "mail name" of your system. This is the
8358 hostname portion of the address to be shown on outgoing
8359 news and mail messages. The default is
8360 <var>syshostname</var>, your system's host name. Mail
8361 name ["<var>syshostname</var>"]:
8363 where <var>syshostname</var> is the output of <tt>hostname
8369 <heading>News system configuration</heading>
8372 All the configuration files related to the NNTP (news)
8373 servers and clients should be located under
8374 <file>/etc/news</file>.</p>
8377 There are some configuration issues that apply to a number
8378 of news clients and server packages on the machine. These
8382 <tag><file>/etc/news/organization</file></tag>
8384 A string which should appear as the
8385 organization header for all messages posted
8386 by NNTP clients on the machine
8389 <tag><file>/etc/news/server</file></tag>
8391 Contains the FQDN of the upstream NNTP
8392 server, or localhost if the local machine is
8397 Other global files may be added as required for cross-package news
8404 <heading>Programs for the X Window System</heading>
8407 <heading>Providing X support and package priorities</heading>
8410 Programs that can be configured with support for the X
8411 Window System must be configured to do so and must declare
8412 any package dependencies necessary to satisfy their
8413 runtime requirements when using the X Window System. If
8414 such a package is of higher priority than the X packages
8415 on which it depends, it is required that either the
8416 X-specific components be split into a separate package, or
8417 that an alternative version of the package, which includes
8418 X support, be provided, or that the package's priority be
8424 <heading>Packages providing an X server</heading>
8427 Packages that provide an X server that, directly or
8428 indirectly, communicates with real input and display
8429 hardware should declare in their control data that they
8430 provide the virtual package <tt>xserver</tt>.<footnote>
8431 This implements current practice, and provides an
8432 actual policy for usage of the <tt>xserver</tt>
8433 virtual package which appears in the virtual packages
8434 list. In a nutshell, X servers that interface
8435 directly with the display and input hardware or via
8436 another subsystem (e.g., GGI) should provide
8437 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8438 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8444 <heading>Packages providing a terminal emulator</heading>
8447 Packages that provide a terminal emulator for the X Window
8448 System which meet the criteria listed below should declare
8449 in their control data that they provide the virtual
8450 package <tt>x-terminal-emulator</tt>. They should also
8451 register themselves as an alternative for
8452 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8457 To be an <tt>x-terminal-emulator</tt>, a program must:
8458 <list compact="compact">
8460 Be able to emulate a DEC VT100 terminal, or a
8461 compatible terminal.
8465 Support the command-line option <tt>-e
8466 <var>command</var></tt>, which creates a new
8467 terminal window<footnote>
8468 "New terminal window" does not necessarily mean
8469 a new top-level X window directly parented by
8470 the window manager; it could, if the terminal
8471 emulator application were so coded, be a new
8472 "view" in a multiple-document interface (MDI).
8474 and runs the specified <var>command</var>,
8475 interpreting the entirety of the rest of the command
8476 line as a command to pass straight to exec, in the
8477 manner that <tt>xterm</tt> does.
8481 Support the command-line option <tt>-T
8482 <var>title</var></tt>, which creates a new terminal
8483 window with the window title <var>title</var>.
8490 <heading>Packages providing a window manager</heading>
8493 Packages that provide a window manager should declare in
8494 their control data that they provide the virtual package
8495 <tt>x-window-manager</tt>. They should also register
8496 themselves as an alternative for
8497 <file>/usr/bin/x-window-manager</file>, with a priority
8498 calculated as follows:
8499 <list compact="compact">
8501 Start with a priority of 20.
8505 If the window manager supports the Debian menu
8506 system, add 20 points if this support is available
8507 in the package's default configuration (i.e., no
8508 configuration files belonging to the system or user
8509 have to be edited to activate the feature); if
8510 configuration files must be modified, add only 10
8516 If the window manager complies with <url
8517 id="http://www.freedesktop.org/Standards/wm-spec"
8518 name="The Window Manager Specification Project">,
8519 written by the <url id="http://www.freedesktop.org/"
8520 name="Free Desktop Group">, add 40 points.
8524 If the window manager permits the X session to be
8525 restarted using a <em>different</em> window manager
8526 (without killing the X server) in its default
8527 configuration, add 10 points; otherwise add none.
8534 <heading>Packages providing fonts</heading>
8537 Packages that provide fonts for the X Window
8539 For the purposes of Debian Policy, a "font for the X
8540 Window System" is one which is accessed via X protocol
8541 requests. Fonts for the Linux console, for PostScript
8542 renderer, or any other purpose, do not fit this
8543 definition. Any tool which makes such fonts available
8544 to the X Window System, however, must abide by this
8547 must do a number of things to ensure that they are both
8548 available without modification of the X or font server
8549 configuration, and that they do not corrupt files used by
8550 other font packages to register information about
8554 Fonts of any type supported by the X Window System
8555 must be in a separate binary package from any
8556 executables, libraries, or documentation (except
8557 that specific to the fonts shipped, such as their
8558 license information). If one or more of the fonts
8559 so packaged are necessary for proper operation of
8560 the package with which they are associated the font
8561 package may be Recommended; if the fonts merely
8562 provide an enhancement, a Suggests relationship may
8563 be used. Packages must not Depend on font
8565 This is because the X server may retrieve fonts
8566 from the local file system or over the network
8567 from an X font server; the Debian package system
8568 is empowered to deal only with the local
8574 BDF fonts must be converted to PCF fonts with the
8575 <prgn>bdftopcf</prgn> utility (available in the
8576 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8577 placed in a directory that corresponds to their
8579 <list compact="compact">
8581 100 dpi fonts must be placed in
8582 <file>/usr/share/fonts/X11/100dpi/</file>.
8586 75 dpi fonts must be placed in
8587 <file>/usr/share/fonts/X11/75dpi/</file>.
8591 Character-cell fonts, cursor fonts, and other
8592 low-resolution fonts must be placed in
8593 <file>/usr/share/fonts/X11/misc/</file>.
8599 Type 1 fonts must be placed in
8600 <file>/usr/share/fonts/X11/Type1/</file>. If font
8601 metric files are available, they must be placed here
8606 Subdirectories of <file>/usr/share/fonts/X11/</file>
8607 other than those listed above must be neither
8608 created nor used. (The <file>PEX</file>, <file>CID</file>,
8609 <file>Speedo</file>, and <file>cyrillic</file> directories
8610 are excepted for historical reasons, but installation of
8611 files into these directories remains discouraged.)
8615 Font packages may, instead of placing files directly
8616 in the X font directories listed above, provide
8617 symbolic links in that font directory pointing to
8618 the files' actual location in the filesystem. Such
8619 a location must comply with the FHS.
8623 Font packages should not contain both 75dpi and
8624 100dpi versions of a font. If both are available,
8625 they should be provided in separate binary packages
8626 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8627 the names of the packages containing the
8628 corresponding fonts.
8632 Fonts destined for the <file>misc</file> subdirectory
8633 should not be included in the same package as 75dpi
8634 or 100dpi fonts; instead, they should be provided in
8635 a separate package with <tt>-misc</tt> appended to
8640 Font packages must not provide the files
8641 <file>fonts.dir</file>, <file>fonts.alias</file>, or
8642 <file>fonts.scale</file> in a font directory:
8645 <file>fonts.dir</file> files must not be provided at all.
8649 <file>fonts.alias</file> and <file>fonts.scale</file>
8650 files, if needed, should be provided in the
8652 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
8653 where <var>fontdir</var> is the name of the
8655 <file>/usr/share/fonts/X11/</file> where the
8656 package's corresponding fonts are stored
8657 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
8658 <var>package</var> is the name of the package
8659 that provides these fonts, and
8660 <var>extension</var> is either <tt>scale</tt>
8661 or <tt>alias</tt>, whichever corresponds to
8668 Font packages must declare a dependency on
8669 <tt>xfonts-utils</tt> in their control
8674 Font packages that provide one or more
8675 <file>fonts.scale</file> files as described above must
8676 invoke <prgn>update-fonts-scale</prgn> on each
8677 directory into which they installed fonts
8678 <em>before</em> invoking
8679 <prgn>update-fonts-dir</prgn> on that directory.
8680 This invocation must occur in both the
8681 <prgn>postinst</prgn> (for all arguments) and
8682 <prgn>postrm</prgn> (for all arguments except
8683 <tt>upgrade</tt>) scripts.
8687 Font packages that provide one or more
8688 <file>fonts.alias</file> files as described above must
8689 invoke <prgn>update-fonts-alias</prgn> on each
8690 directory into which they installed fonts. This
8691 invocation must occur in both the
8692 <prgn>postinst</prgn> (for all arguments) and
8693 <prgn>postrm</prgn> (for all arguments except
8694 <tt>upgrade</tt>) scripts.
8698 Font packages must invoke
8699 <prgn>update-fonts-dir</prgn> on each directory into
8700 which they installed fonts. This invocation must
8701 occur in both the <prgn>postinst</prgn> (for all
8702 arguments) and <prgn>postrm</prgn> (for all
8703 arguments except <tt>upgrade</tt>) scripts.
8707 Font packages must not provide alias names for the
8708 fonts they include which collide with alias names
8709 already in use by fonts already packaged.
8713 Font packages must not provide fonts with the same
8714 XLFD registry name as another font already packaged.
8720 <sect1 id="appdefaults">
8721 <heading>Application defaults files</heading>
8724 Application defaults files must be installed in the
8725 directory <file>/etc/X11/app-defaults/</file> (use of a
8726 localized subdirectory of <file>/etc/X11/</file> as described
8727 in the <em>X Toolkit Intrinsics - C Language
8728 Interface</em> manual is also permitted). They must be
8729 registered as <tt>conffile</tt>s or handled as
8730 configuration files.
8734 Customization of programs' X resources may also be
8735 supported with the provision of a file with the same name
8736 as that of the package placed in
8737 the <file>/etc/X11/Xresources/</file> directory, which
8738 must be registered as a <tt>conffile</tt> or handled as a
8739 configuration file.<footnote>
8740 Note that this mechanism is not the same as using
8741 app-defaults; app-defaults are tied to the client
8742 binary on the local file system, whereas X resources
8743 are stored in the X server and affect all connecting
8750 <heading>Installation directory issues</heading>
8753 Historically, packages using the X Window System used a
8754 separate set of installation directories from other packages.
8755 This practice has been discontinued and packages using the X
8756 Window System should now generally be installed in the same
8757 directories as any other package. Specifically, packages must
8758 not install files under the <file>/usr/X11R6/</file> directory
8759 and the <file>/usr/X11R6/</file> directory hierarchy should be
8760 regarded as obsolete.
8764 Include files previously installed under
8765 <file>/usr/X11R6/include/X11/</file> should be installed into
8766 <file>/usr/include/X11/</file>. For files previously
8767 installed into subdirectories of
8768 <file>/usr/X11R6/lib/X11/</file>, package maintainers should
8769 determine if subdirectories of <file>/usr/lib/</file> and
8770 <file>/usr/share/</file> can be used. If not, a subdirectory
8771 of <file>/usr/lib/X11/</file> should be used.
8775 Configuration files for window, display, or session managers
8776 or other applications that are tightly integrated with the X
8777 Window System may be placed in a subdirectory
8778 of <file>/etc/X11/</file> corresponding to the package name.
8779 Other X Window System applications should use
8780 the <file>/etc/</file> directory unless otherwise mandated by
8781 policy (such as for <ref id="appdefaults">).
8786 <heading>The OSF/Motif and OpenMotif libraries</heading>
8789 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8790 OpenMotif libraries</em><footnote>
8791 OSF/Motif and OpenMotif are collectively referred to as
8792 "Motif" in this policy document.
8794 should be compiled against and tested with LessTif (a free
8795 re-implementation of Motif) instead. If the maintainer
8796 judges that the program or programs do not work
8797 sufficiently well with LessTif to be distributed and
8798 supported, but do so when compiled against Motif, then two
8799 versions of the package should be created; one linked
8800 statically against Motif and with <tt>-smotif</tt>
8801 appended to the package name, and one linked dynamically
8802 against Motif and with <tt>-dmotif</tt> appended to the
8807 Both Motif-linked versions are dependent
8808 upon non-DFSG-compliant software and thus cannot be
8809 uploaded to the <em>main</em> distribution; if the
8810 software is itself DFSG-compliant it may be uploaded to
8811 the <em>contrib</em> distribution. While known existing
8812 versions of Motif permit unlimited redistribution of
8813 binaries linked against the library (whether statically or
8814 dynamically), it is the package maintainer's
8815 responsibility to determine whether this is permitted by
8816 the license of the copy of Motif in their possession.
8822 <heading>Perl programs and modules</heading>
8825 Perl programs and modules should follow the current Perl policy.
8829 The Perl policy can be found in the <tt>perl-policy</tt>
8830 files in the <tt>debian-policy</tt> package.
8831 It is also available from the Debian web mirrors at
8832 <tt><url name="/doc/packaging-manuals/perl-policy/"
8833 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8838 <heading>Emacs lisp programs</heading>
8841 Please refer to the "Debian Emacs Policy" for details of how to
8842 package emacs lisp programs.
8846 The Emacs policy is available in
8847 <file>debian-emacs-policy.gz</file> of the
8848 <package>emacsen-common</package> package.
8849 It is also available from the Debian web mirrors at
8850 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8851 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8856 <heading>Games</heading>
8859 The permissions on <file>/var/games</file> are mode 755, owner
8860 <tt>root</tt> and group <tt>root</tt>.
8864 Each game decides on its own security policy.</p>
8867 Games which require protected, privileged access to
8868 high-score files, saved games, etc., may be made
8869 set-<em>group</em>-id (mode 2755) and owned by
8870 <tt>root:games</tt>, and use files and directories with
8871 appropriate permissions (770 <tt>root:games</tt>, for
8872 example). They must not be made
8873 set-<em>user</em>-id, as this causes security problems. (If
8874 an attacker can subvert any set-user-id game they can
8875 overwrite the executable of any other, causing other players
8876 of these games to run a Trojan horse program. With a
8877 set-group-id game the attacker only gets access to less
8878 important game data, and if they can get at the other
8879 players' accounts at all it will take considerably more
8883 Some packages, for example some fortune cookie programs, are
8884 configured by the upstream authors to install with their
8885 data files or other static information made unreadable so
8886 that they can only be accessed through set-id programs
8887 provided. You should not do this in a Debian package: anyone can
8888 download the <file>.deb</file> file and read the data from it,
8889 so there is no point making the files unreadable. Not
8890 making the files unreadable also means that you don't have
8891 to make so many programs set-id, which reduces the risk of a
8895 As described in the FHS, binaries of games should be
8896 installed in the directory <file>/usr/games</file>. This also
8897 applies to games that use the X Window System. Manual pages
8898 for games (X and non-X games) should be installed in
8899 <file>/usr/share/man/man6</file>.</p>
8905 <heading>Documentation</heading>
8908 <heading>Manual pages</heading>
8911 You should install manual pages in <prgn>nroff</prgn> source
8912 form, in appropriate places under <file>/usr/share/man</file>.
8913 You should only use sections 1 to 9 (see the FHS for more
8914 details). You must not install a pre-formatted "cat page".
8918 Each program, utility, and function should have an
8919 associated manual page included in the same package. It is
8920 suggested that all configuration files also have a manual
8921 page included as well. Manual pages for protocols and other
8922 auxiliary things are optional.
8926 If no manual page is available, this is considered as a bug
8927 and should be reported to the Debian Bug Tracking System (the
8928 maintainer of the package is allowed to write this bug report
8929 themselves, if they so desire). Do not close the bug report
8930 until a proper man page is available.<footnote>
8931 It is not very hard to write a man page. See the
8932 <url id="http://www.schweikhardt.net/man_page_howto.html"
8933 name="Man-Page-HOWTO">,
8934 <manref name="man" section="7">, the examples
8935 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8936 the helper programs <prgn>help2man</prgn>, or the
8937 directory <file>/usr/share/doc/man-db/examples</file>.
8942 You may forward a complaint about a missing man page to the
8943 upstream authors, and mark the bug as forwarded in the
8944 Debian bug tracking system. Even though the GNU Project do
8945 not in general consider the lack of a man page to be a bug,
8946 we do; if they tell you that they don't consider it a bug
8947 you should leave the bug in our bug tracking system open
8952 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8956 If one man page needs to be accessible via several names it
8957 is better to use a symbolic link than the <file>.so</file>
8958 feature, but there is no need to fiddle with the relevant
8959 parts of the upstream source to change from <file>.so</file> to
8960 symlinks: don't do it unless it's easy. You should not
8961 create hard links in the manual page directories, nor put
8962 absolute filenames in <file>.so</file> directives. The filename
8963 in a <file>.so</file> in a man page should be relative to the
8964 base of the man page tree (usually
8965 <file>/usr/share/man</file>). If you do not create any links
8966 (whether symlinks, hard links, or <tt>.so</tt> directives)
8967 in the file system to the alternate names of the man page,
8968 then you should not rely on <prgn>man</prgn> finding your
8969 man page under those names based solely on the information in
8970 the man page's header.<footnote>
8971 Supporting this in <prgn>man</prgn> often requires
8972 unreasonable processing time to find a manual page or to
8973 report that none exists, and moves knowledge into man's
8974 database that would be better left in the file system.
8975 This support is therefore deprecated and will cease to
8976 be present in the future.
8981 Manual pages in locale-specific subdirectories of
8982 <file>/usr/share/man</file> should use either UTF-8 or the usual
8983 legacy encoding for that language (normally the one corresponding
8984 to the shortest relevant locale name in
8985 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
8986 <file>/usr/share/man/fr</file> should use either UTF-8 or
8987 ISO-8859-1.<footnote>
8988 <prgn>man</prgn> will automatically detect whether UTF-8 is in
8989 use. In future, all manual pages will be required to use
8995 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
8996 included in the subdirectory name unless it indicates a
8997 significant difference in the language, as this excludes
8998 speakers of the language in other countries.<footnote>
8999 At the time of writing, Chinese and Portuguese are the main
9000 languages with such differences, so <file>pt_BR</file>,
9001 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
9006 If a localized version of a manual page is provided, it should
9007 either be up-to-date or it should be obvious to the reader that
9008 it is outdated and the original manual page should be used
9009 instead. This can be done either by a note at the beginning of
9010 the manual page or by showing the missing or changed portions in
9011 the original language instead of the target language.
9016 <heading>Info documents</heading>
9019 Info documents should be installed in <file>/usr/share/info</file>.
9020 They should be compressed with <tt>gzip -9</tt>.
9024 The <prgn>install-info</prgn> program maintains a directory of
9025 installed info documents in <file>/usr/share/info/dir</file> for
9026 the use of info readers.<footnote>
9027 It was previously necessary for packages installing info
9028 documents to run <prgn>install-info</prgn> from maintainer
9029 scripts. This is no longer necessary. The installation
9030 system now uses dpkg triggers.
9032 This file must not be included in packages. Packages containing
9033 info documents should depend on <tt>dpkg (>= 1.15.4) |
9034 install-info</tt> to ensure that the directory file is properly
9035 rebuilt during partial upgrades from Debian 5.0 (lenny) and
9040 Info documents should contain section and directory entry
9041 information in the document for the use
9042 of <prgn>install-info</prgn>. The section should be specified
9043 via a line starting with <tt>INFO-DIR-SECTION</tt> followed by a
9044 space and the section of this info page. The directory entry or
9045 entries should be included between
9046 a <tt>START-INFO-DIR-ENTRY</tt> line and
9047 an <tt>END-INFO-DIR-ENTRY</tt> line. For example:
9049 INFO-DIR-SECTION Individual utilities
9050 START-INFO-DIR-ENTRY
9051 * example: (example). An example info directory entry.
9054 To determine which section to use, you should look
9055 at <file>/usr/share/info/dir</file> on your system and choose
9056 the most relevant (or create a new section if none of the
9057 current sections are relevant).<footnote>
9058 Normally, info documents are generated from Texinfo source.
9059 To include this information in the generated info document, if
9060 it is absent, add commands like:
9062 @dircategory Individual utilities
9064 * example: (example). An example info directory entry.
9067 to the Texinfo source of the document and ensure that the info
9068 documents are rebuilt from source during the package build.
9074 <heading>Additional documentation</heading>
9077 Any additional documentation that comes with the package may
9078 be installed at the discretion of the package maintainer.
9079 Plain text documentation should be installed in the directory
9080 <file>/usr/share/doc/<var>package</var></file>, where
9081 <var>package</var> is the name of the package, and
9082 compressed with <tt>gzip -9</tt> unless it is small.
9086 If a package comes with large amounts of documentation which
9087 many users of the package will not require you should create
9088 a separate binary package to contain it, so that it does not
9089 take up disk space on the machines of users who do not need
9090 or want it installed.</p>
9093 It is often a good idea to put text information files
9094 (<file>README</file>s, changelogs, and so forth) that come with
9095 the source package in <file>/usr/share/doc/<var>package</var></file>
9096 in the binary package. However, you don't need to install
9097 the instructions for building and installing the package, of
9101 Packages must not require the existence of any files in
9102 <file>/usr/share/doc/</file> in order to function
9104 The system administrator should be able to
9105 delete files in <file>/usr/share/doc/</file> without causing
9106 any programs to break.
9108 Any files that are referenced by programs but are also
9109 useful as stand alone documentation should be installed under
9110 <file>/usr/share/<var>package</var>/</file> with symbolic links from
9111 <file>/usr/share/doc/<var>package</var></file>.
9115 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9116 link to another directory in <file>/usr/share/doc</file> only if
9117 the two packages both come from the same source and the
9118 first package Depends on the second.<footnote>
9120 Please note that this does not override the section on
9121 changelog files below, so the file
9122 <file>/usr/share/doc/<var>package</var>/changelog.Debian.gz</file>
9123 must refer to the changelog for the current version of
9124 <var>package</var> in question. In practice, this means
9125 that the sources of the target and the destination of the
9126 symlink must be the same (same source package and
9133 Former Debian releases placed all additional documentation
9134 in <file>/usr/doc/<var>package</var></file>. This has been
9135 changed to <file>/usr/share/doc/<var>package</var></file>,
9136 and packages must not put documentation in the directory
9137 <file>/usr/doc/<var>package</var></file>. <footnote>
9138 At this phase of the transition, we no longer require a
9139 symbolic link in <file>/usr/doc/</file>. At a later point,
9140 policy shall change to make the symbolic links a bug.
9146 <heading>Preferred documentation formats</heading>
9149 The unification of Debian documentation is being carried out
9153 If your package comes with extensive documentation in a
9154 markup format that can be converted to various other formats
9155 you should if possible ship HTML versions in a binary
9156 package, in the directory
9157 <file>/usr/share/doc/<var>appropriate-package</var></file> or
9158 its subdirectories.<footnote>
9159 The rationale: The important thing here is that HTML
9160 docs should be available in <em>some</em> package, not
9161 necessarily in the main binary package.
9166 Other formats such as PostScript may be provided at the
9167 package maintainer's discretion.
9171 <sect id="copyrightfile">
9172 <heading>Copyright information</heading>
9175 Every package must be accompanied by a verbatim copy of its
9176 copyright information and distribution license in the file
9177 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
9178 file must neither be compressed nor be a symbolic link.
9182 In addition, the copyright file must say where the upstream
9183 sources (if any) were obtained. It should name the original
9184 authors of the package and the Debian maintainer(s) who were
9185 involved with its creation.
9189 Packages in the <em>contrib</em> or <em>non-free</em> archive
9190 areas should state in the copyright file that the package is not
9191 part of the Debian GNU/Linux distribution and briefly explain
9196 A copy of the file which will be installed in
9197 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9198 be in <file>debian/copyright</file> in the source package.
9202 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9203 link to another directory in <file>/usr/share/doc</file> only if
9204 the two packages both come from the same source and the
9205 first package Depends on the second. These rules are
9206 important because copyrights must be extractable by
9211 Packages distributed under the UCB BSD license, the Apache
9212 license (version 2.0), the Artistic license, the GNU GPL
9213 (version 2 or 3), the GNU LGPL (versions 2, 2.1, or 3), and the
9214 GNU FDL (versions 1.2 or 1.3) should refer to the corresponding
9215 files under <file>/usr/share/common-licenses</file>,<footnote>
9218 <file>/usr/share/common-licenses/BSD</file>,
9219 <file>/usr/share/common-licenses/Apache-2.0</file>,
9220 <file>/usr/share/common-licenses/Artistic</file>,
9221 <file>/usr/share/common-licenses/GPL-2</file>,
9222 <file>/usr/share/common-licenses/GPL-3</file>,
9223 <file>/usr/share/common-licenses/LGPL-2</file>,
9224 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9225 <file>/usr/share/common-licenses/LGPL-3</file>,
9226 <file>/usr/share/common-licenses/GFDL-1.2</file>, and
9227 <file>/usr/share/common-licenses/GFDL-1.3</file>
9230 </footnote> rather than quoting them in the copyright
9235 You should not use the copyright file as a general <file>README</file>
9236 file. If your package has such a file it should be
9237 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9238 <file>README.Debian</file> or some other appropriate place.</p>
9242 <heading>Examples</heading>
9245 Any examples (configurations, source files, whatever),
9246 should be installed in a directory
9247 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9248 files should not be referenced by any program: they're there
9249 for the benefit of the system administrator and users as
9250 documentation only. Architecture-specific example files
9251 should be installed in a directory
9252 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9254 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9255 latter directory itself may be a symbolic link to the
9260 If the purpose of a package is to provide examples, then the
9261 example files may be installed into
9262 <file>/usr/share/doc/<var>package</var></file>.
9266 <sect id="changelogs">
9267 <heading>Changelog files</heading>
9270 Packages that are not Debian-native must contain a
9271 compressed copy of the <file>debian/changelog</file> file from
9272 the Debian source tree in
9273 <file>/usr/share/doc/<var>package</var></file> with the name
9274 <file>changelog.Debian.gz</file>.
9278 If an upstream changelog is available, it should be accessible as
9279 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9280 plain text. If the upstream changelog is distributed in
9281 HTML, it should be made available in that form as
9282 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9283 and a plain text <file>changelog.gz</file> should be generated
9284 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9285 the upstream changelog files do not already conform to this
9286 naming convention, then this may be achieved either by
9287 renaming the files, or by adding a symbolic link, at the
9288 maintainer's discretion.<footnote>
9289 Rationale: People should not have to look in places for
9290 upstream changelogs merely because they are given
9291 different names or are distributed in HTML format.
9296 All of these files should be installed compressed using
9297 <tt>gzip -9</tt>, as they will become large with time even
9298 if they start out small.
9302 If the package has only one changelog which is used both as
9303 the Debian changelog and the upstream one because there is
9304 no separate upstream maintainer then that changelog should
9305 usually be installed as
9306 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9307 there is a separate upstream maintainer, but no upstream
9308 changelog, then the Debian changelog should still be called
9309 <file>changelog.Debian.gz</file>.
9313 For details about the format and contents of the Debian
9314 changelog file, please see <ref id="dpkgchangelog">.
9319 <appendix id="pkg-scope">
9320 <heading>Introduction and scope of these appendices</heading>
9323 These appendices are taken essentially verbatim from the
9324 now-deprecated Packaging Manual, version 3.2.1.0. They are
9325 the chapters which are likely to be of use to package
9326 maintainers and which have not already been included in the
9327 policy document itself. Most of these sections are very likely
9328 not relevant to policy; they should be treated as
9329 documentation for the packaging system. Please note that these
9330 appendices are included for convenience, and for historical
9331 reasons: they used to be part of policy package, and they have
9332 not yet been incorporated into dpkg documentation. However,
9333 they still have value, and hence they are presented here.
9337 They have not yet been checked to ensure that they are
9338 compatible with the contents of policy, and if there are any
9339 contradictions, the version in the main policy document takes
9340 precedence. The remaining chapters of the old Packaging
9341 Manual have also not been read in detail to ensure that there
9342 are not parts which have been left out. Both of these will be
9347 Certain parts of the Packaging manual were integrated into the
9348 Policy Manual proper, and removed from the appendices. Links
9349 have been placed from the old locations to the new ones.
9353 <prgn>dpkg</prgn> is a suite of programs for creating binary
9354 package files and installing and removing them on Unix
9356 <prgn>dpkg</prgn> is targeted primarily at Debian
9357 GNU/Linux, but may work on or be ported to other
9363 The binary packages are designed for the management of
9364 installed executable programs (usually compiled binaries) and
9365 their associated data, though source code examples and
9366 documentation are provided as part of some packages.</p>
9369 This manual describes the technical aspects of creating Debian
9370 binary packages (<file>.deb</file> files). It documents the
9371 behavior of the package management programs
9372 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9373 they interact with packages.</p>
9376 It also documents the interaction between
9377 <prgn>dselect</prgn>'s core and the access method scripts it
9378 uses to actually install the selected packages, and describes
9379 how to create a new access method.</p>
9382 This manual does not go into detail about the options and
9383 usage of the package building and installation tools. It
9384 should therefore be read in conjunction with those programs'
9389 The utility programs which are provided with <prgn>dpkg</prgn>
9390 for managing various system configuration and similar issues,
9391 such as <prgn>update-rc.d</prgn> and
9392 <prgn>install-info</prgn>, are not described in detail here -
9393 please see their man pages.
9397 It is assumed that the reader is reasonably familiar with the
9398 <prgn>dpkg</prgn> System Administrators' manual.
9399 Unfortunately this manual does not yet exist.
9403 The Debian version of the FSF's GNU hello program is provided
9404 as an example for people wishing to create Debian
9405 packages. The Debian <prgn>debmake</prgn> package is
9406 recommended as a very helpful tool in creating and maintaining
9407 Debian packages. However, while the tools and examples are
9408 helpful, they do not replace the need to read and follow the
9409 Policy and Programmer's Manual.</p>
9412 <appendix id="pkg-binarypkg">
9413 <heading>Binary packages (from old Packaging Manual)</heading>
9416 The binary package has two main sections. The first part
9417 consists of various control information files and scripts used
9418 by <prgn>dpkg</prgn> when installing and removing. See <ref
9419 id="pkg-controlarea">.
9423 The second part is an archive containing the files and
9424 directories to be installed.
9428 In the future binary packages may also contain other
9429 components, such as checksums and digital signatures. The
9430 format for the archive is described in full in the
9431 <file>deb(5)</file> man page.
9435 <sect id="pkg-bincreating"><heading>Creating package files -
9436 <prgn>dpkg-deb</prgn>
9440 All manipulation of binary package files is done by
9441 <prgn>dpkg-deb</prgn>; it's the only program that has
9442 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9443 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9444 will spot that the options requested are appropriate to
9445 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9450 In order to create a binary package you must make a
9451 directory tree which contains all the files and directories
9452 you want to have in the file system data part of the package.
9453 In Debian-format source packages this directory is usually
9454 <file>debian/tmp</file>, relative to the top of the package's
9459 They should have the locations (relative to the root of the
9460 directory tree you're constructing) ownerships and
9461 permissions which you want them to have on the system when
9466 With current versions of <prgn>dpkg</prgn> the uid/username
9467 and gid/groupname mappings for the users and groups being
9468 used should be the same on the system where the package is
9469 built and the one where it is installed.
9473 You need to add one special directory to the root of the
9474 miniature file system tree you're creating:
9475 <prgn>DEBIAN</prgn>. It should contain the control
9476 information files, notably the binary package control file
9477 (see <ref id="pkg-controlfile">).
9481 The <prgn>DEBIAN</prgn> directory will not appear in the
9482 file system archive of the package, and so won't be installed
9483 by <prgn>dpkg</prgn> when the package is installed.
9487 When you've prepared the package, you should invoke:
9489 dpkg --build <var>directory</var>
9494 This will build the package in
9495 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9496 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9497 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9502 See the man page <manref name="dpkg-deb" section="8"> for details of how
9503 to examine the contents of this newly-created file. You may find the
9504 output of following commands enlightening:
9506 dpkg-deb --info <var>filename</var>.deb
9507 dpkg-deb --contents <var>filename</var>.deb
9508 dpkg --contents <var>filename</var>.deb
9510 To view the copyright file for a package you could use this command:
9512 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
9517 <sect id="pkg-controlarea">
9518 <heading>Package control information files</heading>
9521 The control information portion of a binary package is a
9522 collection of files with names known to <prgn>dpkg</prgn>.
9523 It will treat the contents of these files specially - some
9524 of them contain information used by <prgn>dpkg</prgn> when
9525 installing or removing the package; others are scripts which
9526 the package maintainer wants <prgn>dpkg</prgn> to run.
9530 It is possible to put other files in the package control
9531 area, but this is not generally a good idea (though they
9532 will largely be ignored).
9536 Here is a brief list of the control info files supported by
9537 <prgn>dpkg</prgn> and a summary of what they're used for.
9542 <tag><tt>control</tt>
9545 This is the key description file used by
9546 <prgn>dpkg</prgn>. It specifies the package's name
9547 and version, gives its description for the user,
9548 states its relationships with other packages, and so
9549 forth. See <ref id="sourcecontrolfiles"> and
9550 <ref id="binarycontrolfiles">.
9554 It is usually generated automatically from information
9555 in the source package by the
9556 <prgn>dpkg-gencontrol</prgn> program, and with
9557 assistance from <prgn>dpkg-shlibdeps</prgn>.
9558 See <ref id="pkg-sourcetools">.
9562 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9567 These are executable files (usually scripts) which
9568 <prgn>dpkg</prgn> runs during installation, upgrade
9569 and removal of packages. They allow the package to
9570 deal with matters which are particular to that package
9571 or require more complicated processing than that
9572 provided by <prgn>dpkg</prgn>. Details of when and
9573 how they are called are in <ref id="maintainerscripts">.
9577 It is very important to make these scripts idempotent.
9578 See <ref id="idempotency">.
9582 The maintainer scripts are guaranteed to run with a
9583 controlling terminal and can interact with the user.
9584 See <ref id="controllingterminal">.
9588 <tag><tt>conffiles</tt>
9591 This file contains a list of configuration files which
9592 are to be handled automatically by <prgn>dpkg</prgn>
9593 (see <ref id="pkg-conffiles">). Note that not necessarily
9594 every configuration file should be listed here.
9597 <tag><tt>shlibs</tt>
9600 This file contains a list of the shared libraries
9601 supplied by the package, with dependency details for
9602 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9603 when it determines what dependencies are required in a
9604 package control file. The <tt>shlibs</tt> file format
9605 is described on <ref id="shlibs">.
9610 <sect id="pkg-controlfile">
9611 <heading>The main control information file: <tt>control</tt></heading>
9614 The most important control information file used by
9615 <prgn>dpkg</prgn> when it installs a package is
9616 <tt>control</tt>. It contains all the package's "vital
9621 The binary package control files of packages built from
9622 Debian sources are made by a special tool,
9623 <prgn>dpkg-gencontrol</prgn>, which reads
9624 <file>debian/control</file> and <file>debian/changelog</file> to
9625 find the information it needs. See <ref id="pkg-sourcepkg"> for
9630 The fields in binary package control files are listed in
9631 <ref id="binarycontrolfiles">.
9635 A description of the syntax of control files and the purpose
9636 of the fields is available in <ref id="controlfields">.
9641 <heading>Time Stamps</heading>
9644 See <ref id="timestamps">.
9649 <appendix id="pkg-sourcepkg">
9650 <heading>Source packages (from old Packaging Manual) </heading>
9653 The Debian binary packages in the distribution are generated
9654 from Debian sources, which are in a special format to assist
9655 the easy and automatic building of binaries.
9658 <sect id="pkg-sourcetools">
9659 <heading>Tools for processing source packages</heading>
9662 Various tools are provided for manipulating source packages;
9663 they pack and unpack sources and help build of binary
9664 packages and help manage the distribution of new versions.
9668 They are introduced and typical uses described here; see
9669 <manref name="dpkg-source" section="1"> for full
9670 documentation about their arguments and operation.
9674 For examples of how to construct a Debian source package,
9675 and how to use those utilities that are used by Debian
9676 source packages, please see the <prgn>hello</prgn> example
9680 <sect1 id="pkg-dpkg-source">
9682 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
9687 This program is frequently used by hand, and is also
9688 called from package-independent automated building scripts
9689 such as <prgn>dpkg-buildpackage</prgn>.
9693 To unpack a package it is typically invoked with
9695 dpkg-source -x <var>.../path/to/filename</var>.dsc
9700 with the <file><var>filename</var>.tar.gz</file> and
9701 <file><var>filename</var>.diff.gz</file> (if applicable) in
9702 the same directory. It unpacks into
9703 <file><var>package</var>-<var>version</var></file>, and if
9705 <file><var>package</var>-<var>version</var>.orig</file>, in
9706 the current directory.
9710 To create a packed source archive it is typically invoked:
9712 dpkg-source -b <var>package</var>-<var>version</var>
9717 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
9718 <file>.diff.gz</file> (if appropriate) in the current
9719 directory. <prgn>dpkg-source</prgn> does not clean the
9720 source tree first - this must be done separately if it is
9725 See also <ref id="pkg-sourcearchives">.</p>
9729 <sect1 id="pkg-dpkg-buildpackage">
9731 <prgn>dpkg-buildpackage</prgn> - overall package-building
9736 <prgn>dpkg-buildpackage</prgn> is a script which invokes
9737 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
9738 targets <tt>clean</tt>, <tt>build</tt> and
9739 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
9740 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
9741 source and binary package upload.
9745 It is usually invoked by hand from the top level of the
9746 built or unbuilt source directory. It may be invoked with
9747 no arguments; useful arguments include:
9748 <taglist compact="compact">
9749 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
9752 Do not sign the <tt>.changes</tt> file or the
9753 source package <tt>.dsc</tt> file, respectively.</p>
9755 <tag><tt>-p<var>sign-command</var></tt></tag>
9758 Invoke <var>sign-command</var> instead of finding
9759 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
9760 <var>sign-command</var> must behave just like
9761 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9763 <tag><tt>-r<var>root-command</var></tt></tag>
9766 When root privilege is required, invoke the command
9767 <var>root-command</var>. <var>root-command</var>
9768 should invoke its first argument as a command, from
9769 the <prgn>PATH</prgn> if necessary, and pass its
9770 second and subsequent arguments to the command it
9771 calls. If no <var>root-command</var> is supplied
9772 then <var>dpkg-buildpackage</var> will take no
9773 special action to gain root privilege, so that for
9774 most packages it will have to be invoked as root to
9777 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9780 Two types of binary-only build and upload - see
9781 <manref name="dpkg-source" section="1">.
9788 <sect1 id="pkg-dpkg-gencontrol">
9790 <prgn>dpkg-gencontrol</prgn> - generates binary package
9795 This program is usually called from <file>debian/rules</file>
9796 (see <ref id="pkg-sourcetree">) in the top level of the source
9801 This is usually done just before the files and directories in the
9802 temporary directory tree where the package is being built have their
9803 permissions and ownerships set and the package is constructed using
9804 <prgn>dpkg-deb/</prgn>
9806 This is so that the control file which is produced has
9807 the right permissions
9812 <prgn>dpkg-gencontrol</prgn> must be called after all the
9813 files which are to go into the package have been placed in
9814 the temporary build directory, so that its calculation of
9815 the installed size of a package is correct.
9819 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9820 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9821 variable substitutions created by
9822 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9827 For a package which generates only one binary package, and
9828 which builds it in <file>debian/tmp</file> relative to the top
9829 of the source package, it is usually sufficient to call
9830 <prgn>dpkg-gencontrol</prgn>.
9834 Sources which build several binaries will typically need
9837 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9838 </example> The <tt>-P</tt> tells
9839 <prgn>dpkg-gencontrol</prgn> that the package is being
9840 built in a non-default directory, and the <tt>-p</tt>
9841 tells it which package's control file should be generated.
9845 <prgn>dpkg-gencontrol</prgn> also adds information to the
9846 list of files in <file>debian/files</file>, for the benefit of
9847 (for example) a future invocation of
9848 <prgn>dpkg-genchanges</prgn>.</p>
9851 <sect1 id="pkg-dpkg-shlibdeps">
9853 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9858 This program is usually called from <file>debian/rules</file>
9859 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9860 id="pkg-sourcetree">), in the top level of the source tree.
9864 Its arguments are executables and shared libraries
9867 They may be specified either in the locations in the
9868 source tree where they are created or in the locations
9869 in the temporary build tree where they are installed
9870 prior to binary package creation.
9872 </footnote> for which shared library dependencies should
9873 be included in the binary package's control file.
9877 If some of the found shared libraries should only
9878 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9879 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9880 by using the <tt>-d<var>dependency-field</var></tt> option
9881 before those executable(s). (Each <tt>-d</tt> option
9882 takes effect until the next <tt>-d</tt>.)
9886 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9887 output control file to be modified. Instead by default it
9888 adds to the <file>debian/substvars</file> file variable
9889 settings like <tt>shlibs:Depends</tt>. These variable
9890 settings must be referenced in dependency fields in the
9891 appropriate per-binary-package sections of the source
9896 For example, a package that generates an essential part
9897 which requires dependencies, and optional parts that
9898 which only require a recommendation, would separate those
9899 two sets of dependencies into two different fields.<footnote>
9900 At the time of writing, an example for this was the
9901 <package/xmms/ package, with Depends used for the xmms
9902 executable, Recommends for the plug-ins and Suggests for
9903 even more optional features provided by unzip.
9905 It can say in its <file>debian/rules</file>:
9907 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9908 -dRecommends <var>optionalpart anotheroptionalpart</var>
9910 and then in its main control file <file>debian/control</file>:
9913 Depends: ${shlibs:Depends}
9914 Recommends: ${shlibs:Recommends}
9920 Sources which produce several binary packages with
9921 different shared library dependency requirements can use
9922 the <tt>-p<var>varnameprefix</var></tt> option to override
9923 the default <tt>shlibs:</tt> prefix (one invocation of
9924 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9925 They can thus produce several sets of dependency
9926 variables, each of the form
9927 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9928 which can be referred to in the appropriate parts of the
9929 binary package control files.
9934 <sect1 id="pkg-dpkg-distaddfile">
9936 <prgn>dpkg-distaddfile</prgn> - adds a file to
9937 <file>debian/files</file>
9941 Some packages' uploads need to include files other than
9942 the source and binary package files.
9946 <prgn>dpkg-distaddfile</prgn> adds a file to the
9947 <file>debian/files</file> file so that it will be included in
9948 the <file>.changes</file> file when
9949 <prgn>dpkg-genchanges</prgn> is run.
9953 It is usually invoked from the <tt>binary</tt> target of
9954 <file>debian/rules</file>:
9956 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9958 The <var>filename</var> is relative to the directory where
9959 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9960 is usually the directory above the top level of the source
9961 tree. The <file>debian/rules</file> target should put the
9962 file there just before or just after calling
9963 <prgn>dpkg-distaddfile</prgn>.
9967 The <var>section</var> and <var>priority</var> are passed
9968 unchanged into the resulting <file>.changes</file> file.
9973 <sect1 id="pkg-dpkg-genchanges">
9975 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9980 This program is usually called by package-independent
9981 automatic building scripts such as
9982 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9987 It is usually called in the top level of a built source
9988 tree, and when invoked with no arguments will print out a
9989 straightforward <file>.changes</file> file based on the
9990 information in the source package's changelog and control
9991 file and the binary and source packages which should have
9997 <sect1 id="pkg-dpkg-parsechangelog">
9999 <prgn>dpkg-parsechangelog</prgn> - produces parsed
10000 representation of a changelog
10004 This program is used internally by
10005 <prgn>dpkg-source</prgn> et al. It may also occasionally
10006 be useful in <file>debian/rules</file> and elsewhere. It
10007 parses a changelog, <file>debian/changelog</file> by default,
10008 and prints a control-file format representation of the
10009 information in it to standard output.
10013 <sect1 id="pkg-dpkg-architecture">
10015 <prgn>dpkg-architecture</prgn> - information about the build and
10020 This program can be used manually, but is also invoked by
10021 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
10022 environment or make variables which specify the build and host
10023 architecture for the package building process.
10028 <sect id="pkg-sourcetree">
10029 <heading>The Debianised source tree</heading>
10032 The source archive scheme described later is intended to
10033 allow a Debianised source tree with some associated control
10034 information to be reproduced and transported easily. The
10035 Debianised source tree is a version of the original program
10036 with certain files added for the benefit of the
10037 Debianisation process, and with any other changes required
10038 made to the rest of the source code and installation
10043 The extra files created for Debian are in the subdirectory
10044 <file>debian</file> of the top level of the Debianised source
10045 tree. They are described below.
10048 <sect1 id="pkg-debianrules">
10049 <heading><file>debian/rules</file> - the main building script</heading>
10052 See <ref id="debianrules">.
10056 <sect1 id="pkg-srcsubstvars">
10057 <heading><file>debian/substvars</file> and variable substitutions</heading>
10060 See <ref id="substvars">.
10066 <heading><file>debian/files</file></heading>
10069 See <ref id="debianfiles">.
10073 <sect1><heading><file>debian/tmp</file>
10077 This is the canonical temporary location for the
10078 construction of binary packages by the <tt>binary</tt>
10079 target. The directory <file>tmp</file> serves as the root of
10080 the file system tree as it is being constructed (for
10081 example, by using the package's upstream makefiles install
10082 targets and redirecting the output there), and it also
10083 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10084 id="pkg-bincreating">.
10088 If several binary packages are generated from the same
10089 source tree it is usual to use several
10090 <file>debian/tmp<var>something</var></file> directories, for
10091 example <file>tmp-a</file> or <file>tmp-doc</file>.
10095 Whatever <file>tmp</file> directories are created and used by
10096 <tt>binary</tt> must of course be removed by the
10097 <tt>clean</tt> target.</p></sect1>
10101 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10105 As it exists on the FTP site, a Debian source package
10106 consists of three related files. You must have the right
10107 versions of all three to be able to use them.
10112 <tag>Debian source control file - <tt>.dsc</tt></tag>
10114 This file is a control file used by <prgn>dpkg-source</prgn>
10115 to extract a source package.
10116 See <ref id="debiansourcecontrolfiles">.
10120 Original source archive -
10122 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10128 This is a compressed (with <tt>gzip -9</tt>)
10129 <prgn>tar</prgn> file containing the source code from
10130 the upstream authors of the program.
10135 Debianisation diff -
10137 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10143 This is a unified context diff (<tt>diff -u</tt>)
10144 giving the changes which are required to turn the
10145 original source into the Debian source. These changes
10146 may only include editing and creating plain files.
10147 The permissions of files, the targets of symbolic
10148 links and the characteristics of special files or
10149 pipes may not be changed and no files may be removed
10154 All the directories in the diff must exist, except the
10155 <file>debian</file> subdirectory of the top of the source
10156 tree, which will be created by
10157 <prgn>dpkg-source</prgn> if necessary when unpacking.
10161 The <prgn>dpkg-source</prgn> program will
10162 automatically make the <file>debian/rules</file> file
10163 executable (see below).</p></item>
10168 If there is no original source code - for example, if the
10169 package is specially prepared for Debian or the Debian
10170 maintainer is the same as the upstream maintainer - the
10171 format is slightly different: then there is no diff, and the
10173 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10174 and preferably contains a directory named
10175 <file><var>package</var>-<var>version</var></file>.
10180 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10183 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10184 Debian source package. However, if it is not available it
10185 is possible to unpack a Debian source archive as follows:
10186 <enumlist compact="compact">
10189 Untar the tarfile, which will create a <file>.orig</file>
10193 <p>Rename the <file>.orig</file> directory to
10194 <file><var>package</var>-<var>version</var></file>.</p>
10198 Create the subdirectory <file>debian</file> at the top of
10199 the source tree.</p>
10201 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10203 <item><p>Untar the tarfile again if you want a copy of the original
10204 source code alongside the Debianised version.</p>
10209 It is not possible to generate a valid Debian source archive
10210 without using <prgn>dpkg-source</prgn>. In particular,
10211 attempting to use <prgn>diff</prgn> directly to generate the
10212 <file>.diff.gz</file> file will not work.
10216 <heading>Restrictions on objects in source packages</heading>
10219 The source package may not contain any hard links
10221 This is not currently detected when building source
10222 packages, but only when extracting
10226 Hard links may be permitted at some point in the
10227 future, but would require a fair amount of
10229 </footnote>, device special files, sockets or setuid or
10232 Setgid directories are allowed.
10237 The source packaging tools manage the changes between the
10238 original and Debianised source using <prgn>diff</prgn> and
10239 <prgn>patch</prgn>. Turning the original source tree as
10240 included in the <file>.orig.tar.gz</file> into the debianised
10241 source must not involve any changes which cannot be
10242 handled by these tools. Problematic changes which cause
10243 <prgn>dpkg-source</prgn> to halt with an error when
10244 building the source package are:
10245 <list compact="compact">
10246 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10248 <item><p>Changing the targets of symbolic links.</p>
10250 <item><p>Creating directories, other than <file>debian</file>.</p>
10252 <item><p>Changes to the contents of binary files.</p></item>
10253 </list> Changes which cause <prgn>dpkg-source</prgn> to
10254 print a warning but continue anyway are:
10255 <list compact="compact">
10258 Removing files, directories or symlinks.
10260 Renaming a file is not treated specially - it is
10261 seen as the removal of the old file (which
10262 generates a warning, but is otherwise ignored),
10263 and the creation of the new one.
10269 Changed text files which are missing the usual final
10270 newline (either in the original or the modified
10275 Changes which are not represented, but which are not detected by
10276 <prgn>dpkg-source</prgn>, are:
10277 <list compact="compact">
10278 <item><p>Changing the permissions of files (other than
10279 <file>debian/rules</file>) and directories.</p></item>
10284 The <file>debian</file> directory and <file>debian/rules</file>
10285 are handled specially by <prgn>dpkg-source</prgn> - before
10286 applying the changes it will create the <file>debian</file>
10287 directory, and afterwards it will make
10288 <file>debian/rules</file> world-executable.
10294 <appendix id="pkg-controlfields">
10295 <heading>Control files and their fields (from old Packaging Manual)</heading>
10298 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10299 data in a common format, known as control files. Binary and
10300 source packages have control data as do the <file>.changes</file>
10301 files which control the installation of uploaded files, and
10302 <prgn>dpkg</prgn>'s internal databases are in a similar
10307 <heading>Syntax of control files</heading>
10310 See <ref id="controlsyntax">.
10314 It is important to note that there are several fields which
10315 are optional as far as <prgn>dpkg</prgn> and the related
10316 tools are concerned, but which must appear in every Debian
10317 package, or whose omission may cause problems.
10322 <heading>List of fields</heading>
10325 See <ref id="controlfieldslist">.
10329 This section now contains only the fields that didn't belong
10330 to the Policy manual.
10333 <sect1 id="pkg-f-Filename">
10334 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10337 These fields in <tt>Packages</tt> files give the
10338 filename(s) of (the parts of) a package in the
10339 distribution directories, relative to the root of the
10340 Debian hierarchy. If the package has been split into
10341 several parts the parts are all listed in order, separated
10346 <sect1 id="pkg-f-Size">
10347 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10350 These fields in <file>Packages</file> files give the size (in
10351 bytes, expressed in decimal) and MD5 checksum of the
10352 file(s) which make(s) up a binary package in the
10353 distribution. If the package is split into several parts
10354 the values for the parts are listed in order, separated by
10359 <sect1 id="pkg-f-Status">
10360 <heading><tt>Status</tt></heading>
10363 This field in <prgn>dpkg</prgn>'s status file records
10364 whether the user wants a package installed, removed or
10365 left alone, whether it is broken (requiring
10366 re-installation) or not and what its current state on the
10367 system is. Each of these pieces of information is a
10372 <sect1 id="pkg-f-Config-Version">
10373 <heading><tt>Config-Version</tt></heading>
10376 If a package is not installed or not configured, this
10377 field in <prgn>dpkg</prgn>'s status file records the last
10378 version of the package which was successfully
10383 <sect1 id="pkg-f-Conffiles">
10384 <heading><tt>Conffiles</tt></heading>
10387 This field in <prgn>dpkg</prgn>'s status file contains
10388 information about the automatically-managed configuration
10389 files held by a package. This field should <em>not</em>
10390 appear anywhere in a package!
10395 <heading>Obsolete fields</heading>
10398 These are still recognized by <prgn>dpkg</prgn> but should
10399 not appear anywhere any more.
10401 <taglist compact="compact">
10403 <tag><tt>Revision</tt></tag>
10404 <tag><tt>Package-Revision</tt></tag>
10405 <tag><tt>Package_Revision</tt></tag>
10407 The Debian revision part of the package version was
10408 at one point in a separate control file field. This
10409 field went through several names.
10412 <tag><tt>Recommended</tt></tag>
10413 <item>Old name for <tt>Recommends</tt>.</item>
10415 <tag><tt>Optional</tt></tag>
10416 <item>Old name for <tt>Suggests</tt>.</item>
10418 <tag><tt>Class</tt></tag>
10419 <item>Old name for <tt>Priority</tt>.</item>
10428 <appendix id="pkg-conffiles">
10429 <heading>Configuration file handling (from old Packaging Manual)</heading>
10432 <prgn>dpkg</prgn> can do a certain amount of automatic
10433 handling of package configuration files.
10437 Whether this mechanism is appropriate depends on a number of
10438 factors, but basically there are two approaches to any
10439 particular configuration file.
10443 The easy method is to ship a best-effort configuration in the
10444 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10445 handle updates. If the user is unlikely to want to edit the
10446 file, but you need them to be able to without losing their
10447 changes, and a new package with a changed version of the file
10448 is only released infrequently, this is a good approach.
10452 The hard method is to build the configuration file from
10453 scratch in the <prgn>postinst</prgn> script, and to take the
10454 responsibility for fixing any mistakes made in earlier
10455 versions of the package automatically. This will be
10456 appropriate if the file is likely to need to be different on
10460 <sect><heading>Automatic handling of configuration files by
10465 A package may contain a control area file called
10466 <tt>conffiles</tt>. This file should be a list of filenames
10467 of configuration files needing automatic handling, separated
10468 by newlines. The filenames should be absolute pathnames,
10469 and the files referred to should actually exist in the
10474 When a package is upgraded <prgn>dpkg</prgn> will process
10475 the configuration files during the configuration stage,
10476 shortly before it runs the package's <prgn>postinst</prgn>
10481 For each file it checks to see whether the version of the
10482 file included in the package is the same as the one that was
10483 included in the last version of the package (the one that is
10484 being upgraded from); it also compares the version currently
10485 installed on the system with the one shipped with the last
10490 If neither the user nor the package maintainer has changed
10491 the file, it is left alone. If one or the other has changed
10492 their version, then the changed version is preferred - i.e.,
10493 if the user edits their file, but the package maintainer
10494 doesn't ship a different version, the user's changes will
10495 stay, silently, but if the maintainer ships a new version
10496 and the user hasn't edited it the new version will be
10497 installed (with an informative message). If both have
10498 changed their version the user is prompted about the problem
10499 and must resolve the differences themselves.
10503 The comparisons are done by calculating the MD5 message
10504 digests of the files, and storing the MD5 of the file as it
10505 was included in the most recent version of the package.
10509 When a package is installed for the first time
10510 <prgn>dpkg</prgn> will install the file that comes with it,
10511 unless that would mean overwriting a file already on the
10516 However, note that <prgn>dpkg</prgn> will <em>not</em>
10517 replace a conffile that was removed by the user (or by a
10518 script). This is necessary because with some programs a
10519 missing file produces an effect hard or impossible to
10520 achieve in another way, so that a missing file needs to be
10521 kept that way if the user did it.
10525 Note that a package should <em>not</em> modify a
10526 <prgn>dpkg</prgn>-handled conffile in its maintainer
10527 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10528 the user confusing and possibly dangerous options for
10529 conffile update when the package is upgraded.</p>
10532 <sect><heading>Fully-featured maintainer script configuration
10537 For files which contain site-specific information such as
10538 the hostname and networking details and so forth, it is
10539 better to create the file in the package's
10540 <prgn>postinst</prgn> script.
10544 This will typically involve examining the state of the rest
10545 of the system to determine values and other information, and
10546 may involve prompting the user for some information which
10547 can't be obtained some other way.
10551 When using this method there are a couple of important
10552 issues which should be considered:
10556 If you discover a bug in the program which generates the
10557 configuration file, or if the format of the file changes
10558 from one version to the next, you will have to arrange for
10559 the postinst script to do something sensible - usually this
10560 will mean editing the installed configuration file to remove
10561 the problem or change the syntax. You will have to do this
10562 very carefully, since the user may have changed the file,
10563 perhaps to fix the very problem that your script is trying
10564 to deal with - you will have to detect these situations and
10565 deal with them correctly.
10569 If you do go down this route it's probably a good idea to
10570 make the program that generates the configuration file(s) a
10571 separate program in <file>/usr/sbin</file>, by convention called
10572 <file><var>package</var>config</file> and then run that if
10573 appropriate from the post-installation script. The
10574 <tt><var>package</var>config</tt> program should not
10575 unquestioningly overwrite an existing configuration - if its
10576 mode of operation is geared towards setting up a package for
10577 the first time (rather than any arbitrary reconfiguration
10578 later) you should have it check whether the configuration
10579 already exists, and require a <tt>--force</tt> flag to
10580 overwrite it.</p></sect>
10583 <appendix id="pkg-alternatives"><heading>Alternative versions of
10584 an interface - <prgn>update-alternatives</prgn> (from old
10589 When several packages all provide different versions of the
10590 same program or file it is useful to have the system select a
10591 default, but to allow the system administrator to change it
10592 and have their decisions respected.
10596 For example, there are several versions of the <prgn>vi</prgn>
10597 editor, and there is no reason to prevent all of them from
10598 being installed at once, each under their own name
10599 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10600 Nevertheless it is desirable to have the name <tt>vi</tt>
10601 refer to something, at least by default.
10605 If all the packages involved cooperate, this can be done with
10606 <prgn>update-alternatives</prgn>.
10610 Each package provides its own version under its own name, and
10611 calls <prgn>update-alternatives</prgn> in its postinst to
10612 register its version (and again in its prerm to deregister
10617 See the man page <manref name="update-alternatives"
10618 section="8"> for details.
10622 If <prgn>update-alternatives</prgn> does not seem appropriate
10623 you may wish to consider using diversions instead.</p>
10626 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10627 package's version of a file (from old Packaging Manual)
10631 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10632 when it reinstalls the package it belongs to, and to have it
10633 put the file from the package somewhere else instead.
10637 This can be used locally to override a package's version of a
10638 file, or by one package to override another's version (or
10639 provide a wrapper for it).
10643 Before deciding to use a diversion, read <ref
10644 id="pkg-alternatives"> to see if you really want a diversion
10645 rather than several alternative versions of a program.
10649 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10650 and updated by a special program <prgn>dpkg-divert</prgn>.
10651 Please see <manref name="dpkg-divert" section="8"> for full
10652 details of its operation.
10656 When a package wishes to divert a file from another, it should
10657 call <prgn>dpkg-divert</prgn> in its preinst to add the
10658 diversion and rename the existing file. For example,
10659 supposing that a <prgn>smailwrapper</prgn> package wishes to
10660 install a wrapper around <file>/usr/sbin/smail</file>:
10662 dpkg-divert --package smailwrapper --add --rename \
10663 --divert /usr/sbin/smail.real /usr/sbin/smail
10664 </example> The <tt>--package smailwrapper</tt> ensures that
10665 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
10666 can bypass the diversion and get installed as the true version.
10667 It's safe to add the diversion unconditionally on upgrades since
10668 it will be left unchanged if it already exists, but
10669 <prgn>dpkg-divert</prgn> will display a message. To suppress that
10670 message, make the command conditional on the version from which
10671 the package is being upgraded:
10673 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
10674 dpkg-divert --package smailwrapper --add --rename \
10675 --divert /usr/sbin/smail.real /usr/sbin/smail
10677 </example> where <tt>1.0-2</tt> is the version at which the
10678 diversion was first added to the package. Running the command
10679 during abort-upgrade is pointless but harmless.
10683 The postrm has to do the reverse:
10685 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
10686 dpkg-divert --package smailwrapper --remove --rename \
10687 --divert /usr/sbin/smail.real /usr/sbin/smail
10689 </example> If the diversion was added at a particular version, the
10690 postrm should also handle the failure case of upgrading from an
10691 older version (unless the older version is so old that direct
10692 upgrades are no longer supported):
10694 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
10695 dpkg-divert --package smailwrapper --remove --rename \
10696 --divert /usr/sbin/smail.real /usr/sbin/smail
10698 </example> where <tt>1.02-2</tt> is the version at which the
10699 diversion was first added to the package. The postrm should not
10700 remove the diversion on upgrades both because there's no reason to
10701 remove the diversion only to immediately re-add it and since the
10702 postrm of the old package is run after unpacking so the removal of
10703 the diversion will fail.
10707 Do not attempt to divert a file which is vitally important for
10708 the system's operation - when using <prgn>dpkg-divert</prgn>
10709 there is a time, after it has been diverted but before
10710 <prgn>dpkg</prgn> has installed the new version, when the file
10711 does not exist.</p>
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