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10 <title>Debian Policy Manual</title>
11 <author><qref id="authors">The Debian Policy Mailing List</qref></author>
12 <version>version &version;, &date;</version>
15 This manual describes the policy requirements for the Debian
16 GNU/Linux distribution. This includes the structure and
17 contents of the Debian archive and several design issues of
18 the operating system, as well as technical requirements that
19 each package must satisfy to be included in the distribution.
24 Copyright © 1996,1997,1998 Ian Jackson
25 and Christian Schwarz.
28 These are the copyright dates of the original Policy manual.
29 Since then, this manual has been updated by many others. No
30 comprehensive collection of copyright notices for subsequent
35 This manual is free software; you may redistribute it and/or
36 modify it under the terms of the GNU General Public License
37 as published by the Free Software Foundation; either version
38 2, or (at your option) any later version.
42 This is distributed in the hope that it will be useful, but
43 <em>without any warranty</em>; without even the implied
44 warranty of merchantability or fitness for a particular
45 purpose. See the GNU General Public License for more
50 A copy of the GNU General Public License is available as
51 <file>/usr/share/common-licenses/GPL</file> in the Debian GNU/Linux
52 distribution or on the World Wide Web at
53 <url id="http://www.gnu.org/copyleft/gpl.html"
54 name="the GNU General Public Licence">. You can also
55 obtain it by writing to the Free Software Foundation, Inc.,
56 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
64 <heading>About this manual</heading>
66 <heading>Scope</heading>
68 This manual describes the policy requirements for the Debian
69 GNU/Linux distribution. This includes the structure and
70 contents of the Debian archive and several design issues of the
71 operating system, as well as technical requirements that
72 each package must satisfy to be included in the
77 This manual also describes Debian policy as it relates to
78 creating Debian packages. It is not a tutorial on how to build
79 packages, nor is it exhaustive where it comes to describing
80 the behavior of the packaging system. Instead, this manual
81 attempts to define the interface to the package management
82 system that the developers have to be conversant with.<footnote>
83 Informally, the criteria used for inclusion is that the
84 material meet one of the following requirements:
85 <taglist compact="compact">
86 <tag>Standard interfaces</tag>
88 The material presented represents an interface to
89 the packaging system that is mandated for use, and
90 is used by, a significant number of packages, and
91 therefore should not be changed without peer
92 review. Package maintainers can then rely on this
93 interface not changing, and the package management
94 software authors need to ensure compatibility with
95 this interface definition. (Control file and
96 changelog file formats are examples.)
98 <tag>Chosen Convention</tag>
100 If there are a number of technically viable choices
101 that can be made, but one needs to select one of
102 these options for inter-operability. The version
103 number format is one example.
106 Please note that these are not mutually exclusive;
107 selected conventions often become parts of standard
113 The footnotes present in this manual are
114 merely informative, and are not part of Debian policy itself.
118 The appendices to this manual are not necessarily normative,
119 either. Please see <ref id="pkg-scope"> for more information.
123 In the normative part of this manual,
124 the words <em>must</em>, <em>should</em> and
125 <em>may</em>, and the adjectives <em>required</em>,
126 <em>recommended</em> and <em>optional</em>, are used to
127 distinguish the significance of the various guidelines in
128 this policy document. Packages that do not conform to the
129 guidelines denoted by <em>must</em> (or <em>required</em>)
130 will generally not be considered acceptable for the Debian
131 distribution. Non-conformance with guidelines denoted by
132 <em>should</em> (or <em>recommended</em>) will generally be
133 considered a bug, but will not necessarily render a package
134 unsuitable for distribution. Guidelines denoted by
135 <em>may</em> (or <em>optional</em>) are truly optional and
136 adherence is left to the maintainer's discretion.
140 These classifications are roughly equivalent to the bug
141 severities <em>serious</em> (for <em>must</em> or
142 <em>required</em> directive violations), <em>minor</em>,
143 <em>normal</em> or <em>important</em>
144 (for <em>should</em> or <em>recommended</em> directive
145 violations) and <em>wishlist</em> (for <em>optional</em>
148 Compare RFC 2119. Note, however, that these words are
149 used in a different way in this document.
154 Much of the information presented in this manual will be
155 useful even when building a package which is to be
156 distributed in some other way or is intended for local use
162 <heading>New versions of this document</heading>
165 This manual is distributed via the Debian package
166 <package><url name="debian-policy"
167 id="http://packages.debian.org/debian-policy"></package>
168 (<httpsite>packages.debian.org</httpsite>
169 <httppath>/debian-policy</httppath>).
173 The current version of this document is also available from
174 the Debian web mirrors at
175 <tt><url name="/doc/debian-policy/"
176 id="http://www.debian.org/doc/debian-policy/"></tt>.
178 <httpsite>www.debian.org</httpsite>
179 <httppath>/doc/debian-policy/</httppath>)
180 Also available from the same directory are several other
181 formats: <file>policy.html.tar.gz</file>
182 (<httppath>/doc/debian-policy/policy.html.tar.gz</httppath>),
183 <file>policy.pdf.gz</file>
184 (<httppath>/doc/debian-policy/policy.pdf.gz</httppath>)
185 and <file>policy.ps.gz</file>
186 (<httppath>/doc/debian-policy/policy.ps.gz</httppath>).
190 The <package>debian-policy</package> package also includes the file
191 <file>upgrading-checklist.txt.gz</file> which indicates policy
192 changes between versions of this document.
197 <heading>Authors and Maintainers</heading>
200 Originally called "Debian GNU/Linux Policy Manual", this
201 manual was initially written in 1996 by Ian Jackson.
202 It was revised on November 27th, 1996 by David A. Morris.
203 Christian Schwarz added new sections on March 15th, 1997,
204 and reworked/restructured it in April-July 1997.
205 Christoph Lameter contributed the "Web Standard".
206 Julian Gilbey largely restructured it in 2001.
210 Since September 1998, the responsibility for the contents of
211 this document lies on the <url name="debian-policy mailing list"
212 id="mailto:debian-policy@lists.debian.org">. Proposals
213 are discussed there and inserted into policy after a certain
214 consensus is established.
215 <!-- insert shameless policy-process plug here eventually -->
216 The actual editing is done by a group of maintainers that have
217 no editorial powers. These are the current maintainers:
220 <item>Julian Gilbey</item>
221 <item>Branden Robinson</item>
222 <item>Josip Rodin</item>
223 <item>Manoj Srivastava</item>
228 While the authors of this document have tried hard to avoid
229 typos and other errors, these do still occur. If you discover
230 an error in this manual or if you want to give any
231 comments, suggestions, or criticisms please send an email to
232 the Debian Policy List,
233 <email>debian-policy@lists.debian.org</email>, or submit a
234 bug report against the <tt>debian-policy</tt> package.
238 Please do not try to reach the individual authors or maintainers
239 of the Policy Manual regarding changes to the Policy.
244 <heading>Related documents</heading>
247 There are several other documents other than this Policy Manual
248 that are necessary to fully understand some Debian policies and
253 The external "sub-policy" documents are referred to in:
254 <list compact="compact">
255 <item><ref id="fhs"></item>
256 <item><ref id="virtual_pkg"></item>
257 <item><ref id="menus"></item>
258 <item><ref id="mime"></item>
259 <item><ref id="perl"></item>
260 <item><ref id="maintscriptprompt"></item>
261 <item><ref id="emacs"></item>
266 In addition to those, which carry the weight of policy, there
267 is the Debian Developer's Reference. This document describes
268 procedures and resources for Debian developers, but it is
269 <em>not</em> normative; rather, it includes things that don't
270 belong in the Policy, such as best practices for developers.
274 The Developer's Reference is available in the
275 <package>developers-reference</package> package.
276 It's also available from the Debian web mirrors at
277 <tt><url name="/doc/developers-reference/"
278 id="http://www.debian.org/doc/developers-reference/"></tt>.
282 <sect id="definitions">
283 <heading>Definitions</heading>
286 The following terms are used in this Policy Manual:
290 The character encoding specified by ANSI X3.4-1986 and its
291 predecessor standards, referred to in MIME as US-ASCII, and
292 corresponding to an encoding in eight bits per character of
293 the first 128 <url id="http://www.unicode.org/"
294 name="Unicode"> characters, with the eighth bit always zero.
298 The transformation format (sometimes called encoding) of
299 <url id="http://www.unicode.org/" name="Unicode"> defined by
300 <url id="http://www.rfc-editor.org/rfc/rfc3629.txt"
301 name="RFC 3629">. UTF-8 has the useful property of having
302 ASCII as a subset, so any text encoded in ASCII is trivially
312 <heading>The Debian Archive</heading>
315 The Debian GNU/Linux system is maintained and distributed as a
316 collection of <em>packages</em>. Since there are so many of
317 them (currently well over 15000), they are split into
318 <em>sections</em> and given <em>priorities</em> to simplify
319 the handling of them.
323 The effort of the Debian project is to build a free operating
324 system, but not every package we want to make accessible is
325 <em>free</em> in our sense (see the Debian Free Software
326 Guidelines, below), or may be imported/exported without
327 restrictions. Thus, the archive is split into areas<footnote>
328 The Debian archive software uses the term "component" internally
329 and in the Release file format to refer to the division of an
330 archive. The Debian Social Contract simply refers to "areas."
331 This document uses terminology similar to the Social Contract.
332 </footnote> based on their licenses and other restrictions.
336 The aims of this are:
338 <list compact="compact">
339 <item>to allow us to make as much software available as we can</item>
340 <item>to allow us to encourage everyone to write free software,
342 <item>to allow us to make it easy for people to produce
343 CD-ROMs of our system without violating any licenses,
344 import/export restrictions, or any other laws.</item>
349 The <em>main</em> archive area forms the <em>Debian GNU/Linux
354 Packages in the other archive areas (<tt>contrib</tt>,
355 <tt>non-free</tt>) are not considered to be part of the Debian
356 distribution, although we support their use and provide
357 infrastructure for them (such as our bug-tracking system and
358 mailing lists). This Debian Policy Manual applies to these
363 <heading>The Debian Free Software Guidelines</heading>
365 The Debian Free Software Guidelines (DFSG) form our
366 definition of "free software". These are:
368 <tag>1. Free Redistribution
371 The license of a Debian component may not restrict any
372 party from selling or giving away the software as a
373 component of an aggregate software distribution
374 containing programs from several different
375 sources. The license may not require a royalty or
376 other fee for such sale.
381 The program must include source code, and must allow
382 distribution in source code as well as compiled form.
384 <tag>3. Derived Works
387 The license must allow modifications and derived
388 works, and must allow them to be distributed under the
389 same terms as the license of the original software.
391 <tag>4. Integrity of The Author's Source Code
394 The license may restrict source-code from being
395 distributed in modified form <em>only</em> if the
396 license allows the distribution of "patch files"
397 with the source code for the purpose of modifying the
398 program at build time. The license must explicitly
399 permit distribution of software built from modified
400 source code. The license may require derived works to
401 carry a different name or version number from the
402 original software. (This is a compromise. The Debian
403 Project encourages all authors to not restrict any
404 files, source or binary, from being modified.)
406 <tag>5. No Discrimination Against Persons or Groups
409 The license must not discriminate against any person
412 <tag>6. No Discrimination Against Fields of Endeavor
415 The license must not restrict anyone from making use
416 of the program in a specific field of endeavor. For
417 example, it may not restrict the program from being
418 used in a business, or from being used for genetic
421 <tag>7. Distribution of License
424 The rights attached to the program must apply to all
425 to whom the program is redistributed without the need
426 for execution of an additional license by those
429 <tag>8. License Must Not Be Specific to Debian
432 The rights attached to the program must not depend on
433 the program's being part of a Debian system. If the
434 program is extracted from Debian and used or
435 distributed without Debian but otherwise within the
436 terms of the program's license, all parties to whom
437 the program is redistributed must have the same
438 rights as those that are granted in conjunction with
441 <tag>9. License Must Not Contaminate Other Software
444 The license must not place restrictions on other
445 software that is distributed along with the licensed
446 software. For example, the license must not insist
447 that all other programs distributed on the same medium
448 must be free software.
450 <tag>10. Example Licenses
453 The "GPL," "BSD," and "Artistic" licenses are examples of
454 licenses that we consider <em>free</em>.
461 <heading>Archive areas</heading>
464 <heading>The main archive area</heading>
467 Every package in <em>main</em> must comply with the DFSG
468 (Debian Free Software Guidelines).
472 In addition, the packages in <em>main</em>
473 <list compact="compact">
475 must not require a package outside of <em>main</em>
476 for compilation or execution (thus, the package must
477 not declare a "Depends", "Recommends", or
478 "Build-Depends" relationship on a non-<em>main</em>
482 must not be so buggy that we refuse to support them,
486 must meet all policy requirements presented in this
495 <heading>The contrib archive area</heading>
498 Every package in <em>contrib</em> must comply with the DFSG.
502 In addition, the packages in <em>contrib</em>
503 <list compact="compact">
505 must not be so buggy that we refuse to support them,
509 must meet all policy requirements presented in this
517 Examples of packages which would be included in
518 <em>contrib</em> are:
519 <list compact="compact">
521 free packages which require <em>contrib</em>,
522 <em>non-free</em> packages or packages which are not
523 in our archive at all for compilation or execution,
527 wrapper packages or other sorts of free accessories for
534 <sect1 id="non-free">
535 <heading>The non-free archive area</heading>
538 Packages must be placed in <em>non-free</em> if they are
539 not compliant with the DFSG or are encumbered by patents
540 or other legal issues that make their distribution
545 In addition, the packages in <em>non-free</em>
546 <list compact="compact">
548 must not be so buggy that we refuse to support them,
552 must meet all policy requirements presented in this
553 manual that it is possible for them to meet.
555 It is possible that there are policy
556 requirements which the package is unable to
557 meet, for example, if the source is
558 unavailable. These situations will need to be
559 handled on a case-by-case basis.
568 <sect id="pkgcopyright">
569 <heading>Copyright considerations</heading>
572 Every package must be accompanied by a verbatim copy of its
573 copyright information and distribution license in the file
574 <file>/usr/share/doc/<var>package</var>/copyright</file>
575 (see <ref id="copyrightfile"> for further details).
579 We reserve the right to restrict files from being included
580 anywhere in our archives if
581 <list compact="compact">
583 their use or distribution would break a law,
586 there is an ethical conflict in their distribution or
590 we would have to sign a license for them, or
593 their distribution would conflict with other project
600 Programs whose authors encourage the user to make
601 donations are fine for the main distribution, provided
602 that the authors do not claim that not donating is
603 immoral, unethical, illegal or something similar; in such
604 a case they must go in <em>non-free</em>.
608 Packages whose copyright permission notices (or patent
609 problems) do not even allow redistribution of binaries
610 only, and where no special permission has been obtained,
611 must not be placed on the Debian FTP site and its mirrors
616 Note that under international copyright law (this applies
617 in the United States, too), <em>no</em> distribution or
618 modification of a work is allowed without an explicit
619 notice saying so. Therefore a program without a copyright
620 notice <em>is</em> copyrighted and you may not do anything
621 to it without risking being sued! Likewise if a program
622 has a copyright notice but no statement saying what is
623 permitted then nothing is permitted.
627 Many authors are unaware of the problems that restrictive
628 copyrights (or lack of copyright notices) can cause for
629 the users of their supposedly-free software. It is often
630 worthwhile contacting such authors diplomatically to ask
631 them to modify their license terms. However, this can be a
632 politically difficult thing to do and you should ask for
633 advice on the <tt>debian-legal</tt> mailing list first, as
638 When in doubt about a copyright, send mail to
639 <email>debian-legal@lists.debian.org</email>. Be prepared
640 to provide us with the copyright statement. Software
641 covered by the GPL, public domain software and BSD-like
642 copyrights are safe; be wary of the phrases "commercial
643 use prohibited" and "distribution restricted".
647 <sect id="subsections">
648 <heading>Sections</heading>
651 The packages in the archive areas <em>main</em>,
652 <em>contrib</em> and <em>non-free</em> are grouped further into
653 <em>sections</em> to simplify handling.
657 The archive area and section for each package should be
658 specified in the package's <tt>Section</tt> control record (see
659 <ref id="f-Section">). However, the maintainer of the Debian
660 archive may override this selection to ensure the consistency of
661 the Debian distribution. The <tt>Section</tt> field should be
663 <list compact="compact">
665 <em>section</em> if the package is in the
666 <em>main</em> archive area,
669 <em>area/section</em> if the package is in
670 the <em>contrib</em> or <em>non-free</em>
677 The Debian archive maintainers provide the authoritative
678 list of sections. At present, they are:
679 <em>admin</em>, <em>cli-mono</em>, <em>comm</em>, <em>database</em>,
680 <em>devel</em>, <em>debug</em>, <em>doc</em>, <em>editors</em>,
681 <em>electronics</em>, <em>embedded</em>, <em>fonts</em>,
682 <em>games</em>, <em>gnome</em>, <em>graphics</em>, <em>gnu-r</em>,
683 <em>gnustep</em>, <em>hamradio</em>, <em>haskell</em>,
684 <em>httpd</em>, <em>interpreters</em>, <em>java</em>, <em>kde</em>,
685 <em>kernel</em>, <em>libs</em>, <em>libdevel</em>, <em>lisp</em>,
686 <em>localization</em>, <em>mail</em>, <em>math</em>, <em>misc</em>,
687 <em>net</em>, <em>news</em>, <em>ocaml</em>, <em>oldlibs</em>,
688 <em>otherosfs</em>, <em>perl</em>, <em>php</em>, <em>python</em>,
689 <em>ruby</em>, <em>science</em>, <em>shells</em>, <em>sound</em>,
690 <em>tex</em>, <em>text</em>, <em>utils</em>, <em>vcs</em>,
691 <em>video</em>, <em>web</em>, <em>x11</em>, <em>xfce</em>,
692 <em>zope</em>. The additional section <em>debian-installer</em>
693 contains special packages used by the installer and is not used
694 for normal Debian packages.
698 For more information about the sections and their definitions,
699 see the <url id="http://packages.debian.org/unstable/"
700 name="list of sections in unstable">.
704 <sect id="priorities">
705 <heading>Priorities</heading>
708 Each package should have a <em>priority</em> value, which is
709 included in the package's <em>control record</em>
710 (see <ref id="f-Priority">).
711 This information is used by the Debian package management tools to
712 separate high-priority packages from less-important packages.
716 The following <em>priority levels</em> are recognized by the
717 Debian package management tools.
719 <tag><tt>required</tt></tag>
721 Packages which are necessary for the proper
722 functioning of the system (usually, this means that
723 dpkg functionality depends on these packages).
724 Removing a <tt>required</tt> package may cause your
725 system to become totally broken and you may not even
726 be able to use <prgn>dpkg</prgn> to put things back,
727 so only do so if you know what you are doing. Systems
728 with only the <tt>required</tt> packages are probably
729 unusable, but they do have enough functionality to
730 allow the sysadmin to boot and install more software.
732 <tag><tt>important</tt></tag>
734 Important programs, including those which one would
735 expect to find on any Unix-like system. If the
736 expectation is that an experienced Unix person who
737 found it missing would say "What on earth is going on,
738 where is <prgn>foo</prgn>?", it must be an
739 <tt>important</tt> package.<footnote>
740 This is an important criterion because we are
741 trying to produce, amongst other things, a free
744 Other packages without which the system will not run
745 well or be usable must also have priority
746 <tt>important</tt>. This does
747 <em>not</em> include Emacs, the X Window System, TeX
748 or any other large applications. The
749 <tt>important</tt> packages are just a bare minimum of
750 commonly-expected and necessary tools.
752 <tag><tt>standard</tt></tag>
754 These packages provide a reasonably small but not too
755 limited character-mode system. This is what will be
756 installed by default if the user doesn't select anything
757 else. It doesn't include many large applications.
759 <tag><tt>optional</tt></tag>
761 (In a sense everything that isn't required is
762 optional, but that's not what is meant here.) This is
763 all the software that you might reasonably want to
764 install if you didn't know what it was and don't have
765 specialized requirements. This is a much larger system
766 and includes the X Window System, a full TeX
767 distribution, and many applications. Note that
768 optional packages should not conflict with each other.
770 <tag><tt>extra</tt></tag>
772 This contains all packages that conflict with others
773 with required, important, standard or optional
774 priorities, or are only likely to be useful if you
775 already know what they are or have specialized
776 requirements (such as packages containing only detached
783 Packages must not depend on packages with lower priority
784 values (excluding build-time dependencies). In order to
785 ensure this, the priorities of one or more packages may need
794 <heading>Binary packages</heading>
797 The Debian GNU/Linux distribution is based on the Debian
798 package management system, called <prgn>dpkg</prgn>. Thus,
799 all packages in the Debian distribution must be provided
800 in the <tt>.deb</tt> file format.
804 <heading>The package name</heading>
807 Every package must have a name that's unique within the Debian
812 The package name is included in the control field
813 <tt>Package</tt>, the format of which is described
814 in <ref id="f-Package">.
815 The package name is also included as a part of the file name
816 of the <tt>.deb</tt> file.
821 <heading>The version of a package</heading>
824 Every package has a version number recorded in its
825 <tt>Version</tt> control file field, described in
826 <ref id="f-Version">.
830 The package management system imposes an ordering on version
831 numbers, so that it can tell whether packages are being up- or
832 downgraded and so that package system front end applications
833 can tell whether a package it finds available is newer than
834 the one installed on the system. The version number format
835 has the most significant parts (as far as comparison is
836 concerned) at the beginning.
840 If an upstream package has problematic version numbers they
841 should be converted to a sane form for use in the
842 <tt>Version</tt> field.
846 <heading>Version numbers based on dates</heading>
849 In general, Debian packages should use the same version
850 numbers as the upstream sources.
854 However, in some cases where the upstream version number is
855 based on a date (e.g., a development "snapshot" release) the
856 package management system cannot handle these version
857 numbers without epochs. For example, dpkg will consider
858 "96May01" to be greater than "96Dec24".
862 To prevent having to use epochs for every new upstream
863 version, the date based portion of the version number
864 should be changed to the following format in such cases:
865 "19960501", "19961224". It is up to the maintainer whether
866 they want to bother the upstream maintainer to change
867 the version numbers upstream, too.
871 Note that other version formats based on dates which are
872 parsed correctly by the package management system should
873 <em>not</em> be changed.
877 Native Debian packages (i.e., packages which have been
878 written especially for Debian) whose version numbers include
879 dates should always use the "YYYYMMDD" format.
886 <heading>The maintainer of a package</heading>
889 Every package must have a Debian maintainer (the
890 maintainer may be one person or a group of people
891 reachable from a common email address, such as a mailing
892 list). The maintainer is responsible for ensuring that
893 the package is placed in the appropriate distributions.
897 The maintainer must be specified in the
898 <tt>Maintainer</tt> control field with their correct name
899 and a working email address. If one person maintains
900 several packages, they should try to avoid having
901 different forms of their name and email address in
902 the <tt>Maintainer</tt> fields of those packages.
906 The format of the <tt>Maintainer</tt> control field is
907 described in <ref id="f-Maintainer">.
911 If the maintainer of a package quits from the Debian
912 project, "Debian QA Group"
913 <email>packages@qa.debian.org</email> takes over the
914 maintainer-ship of the package until someone else
915 volunteers for that task. These packages are called
916 <em>orphaned packages</em>.<footnote>
917 The detailed procedure for doing this gracefully can
918 be found in the Debian Developer's Reference,
919 see <ref id="related">.
924 <sect id="descriptions">
925 <heading>The description of a package</heading>
928 Every Debian package must have an extended description
929 stored in the appropriate field of the control record.
930 The technical information about the format of the
931 <tt>Description</tt> field is in <ref id="f-Description">.
935 The description should describe the package (the program) to a
936 user (system administrator) who has never met it before so that
937 they have enough information to decide whether they want to
938 install it. This description should not just be copied verbatim
939 from the program's documentation.
943 Put important information first, both in the synopsis and
944 extended description. Sometimes only the first part of the
945 synopsis or of the description will be displayed. You can
946 assume that there will usually be a way to see the whole
947 extended description.
951 The description should also give information about the
952 significant dependencies and conflicts between this package
953 and others, so that the user knows why these dependencies and
954 conflicts have been declared.
958 Instructions for configuring or using the package should
959 not be included (that is what installation scripts,
960 manual pages, info files, etc., are for). Copyright
961 statements and other administrivia should not be included
962 either (that is what the copyright file is for).
965 <sect1 id="synopsis"><heading>The single line synopsis</heading>
968 The single line synopsis should be kept brief - certainly
973 Do not include the package name in the synopsis line. The
974 display software knows how to display this already, and you
975 do not need to state it. Remember that in many situations
976 the user may only see the synopsis line - make it as
977 informative as you can.
982 <sect1 id="extendeddesc"><heading>The extended description</heading>
985 Do not try to continue the single line synopsis into the
986 extended description. This will not work correctly when
987 the full description is displayed, and makes no sense
988 where only the summary (the single line synopsis) is
993 The extended description should describe what the package
994 does and how it relates to the rest of the system (in terms
995 of, for example, which subsystem it is which part of).
999 The description field needs to make sense to anyone, even
1000 people who have no idea about any of the things the
1001 package deals with.<footnote>
1002 The blurb that comes with a program in its
1003 announcements and/or <prgn>README</prgn> files is
1004 rarely suitable for use in a description. It is
1005 usually aimed at people who are already in the
1006 community where the package is used.
1015 <heading>Dependencies</heading>
1018 Every package must specify the dependency information
1019 about other packages that are required for the first to
1024 For example, a dependency entry must be provided for any
1025 shared libraries required by a dynamically-linked executable
1026 binary in a package.
1030 Packages are not required to declare any dependencies they
1031 have on other packages which are marked <tt>Essential</tt>
1032 (see below), and should not do so unless they depend on a
1033 particular version of that package.<footnote>
1035 Essential is needed in part to avoid unresolvable dependency
1036 loops on upgrade. If packages add unnecessary dependencies
1037 on packages in this set, the chances that there
1038 <strong>will</strong> be an unresolvable dependency loop
1039 caused by forcing these Essential packages to be configured
1040 first before they need to be is greatly increased. It also
1041 increases the chances that frontends will be unable to
1042 <strong>calculate</strong> an upgrade path, even if one
1046 Also, functionality is rarely ever removed from the
1047 Essential set, but <em>packages</em> have been removed from
1048 the Essential set when the functionality moved to a
1049 different package. So depending on these packages <em>just
1050 in case</em> they stop being essential does way more harm
1057 Sometimes, a package requires another package to be installed
1058 <em>and</em> configured before it can be installed. In this
1059 case, you must specify a <tt>Pre-Depends</tt> entry for
1064 You should not specify a <tt>Pre-Depends</tt> entry for a
1065 package before this has been discussed on the
1066 <tt>debian-devel</tt> mailing list and a consensus about
1067 doing that has been reached.
1071 The format of the package interrelationship control fields is
1072 described in <ref id="relationships">.
1076 <sect id="virtual_pkg">
1077 <heading>Virtual packages</heading>
1080 Sometimes, there are several packages which offer
1081 more-or-less the same functionality. In this case, it's
1082 useful to define a <em>virtual package</em> whose name
1083 describes that common functionality. (The virtual
1084 packages only exist logically, not physically; that's why
1085 they are called <em>virtual</em>.) The packages with this
1086 particular function will then <em>provide</em> the virtual
1087 package. Thus, any other package requiring that function
1088 can simply depend on the virtual package without having to
1089 specify all possible packages individually.
1093 All packages should use virtual package names where
1094 appropriate, and arrange to create new ones if necessary.
1095 They should not use virtual package names (except privately,
1096 amongst a cooperating group of packages) unless they have
1097 been agreed upon and appear in the list of virtual package
1098 names. (See also <ref id="virtual">)
1102 The latest version of the authoritative list of virtual
1103 package names can be found in the <tt>debian-policy</tt> package.
1104 It is also available from the Debian web mirrors at
1105 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1106 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>.
1110 The procedure for updating the list is described in the preface
1117 <heading>Base system</heading>
1120 The <tt>base system</tt> is a minimum subset of the Debian
1121 GNU/Linux system that is installed before everything else
1122 on a new system. Only very few packages are allowed to form
1123 part of the base system, in order to keep the required disk
1128 The base system consists of all those packages with priority
1129 <tt>required</tt> or <tt>important</tt>. Many of them will
1130 be tagged <tt>essential</tt> (see below).
1135 <heading>Essential packages</heading>
1138 Essential is defined as the minimal set of functionality that
1139 must be available and usable on the system at all times, even
1140 when packages are in an unconfigured (but unpacked) state.
1141 Packages are tagged <tt>essential</tt> for a system using the
1142 <tt>Essential</tt> control file field. The format of the
1143 <tt>Essential</tt> control field is described in <ref
1148 Since these packages cannot be easily removed (one has to
1149 specify an extra <em>force option</em> to
1150 <prgn>dpkg</prgn> to do so), this flag must not be used
1151 unless absolutely necessary. A shared library package
1152 must not be tagged <tt>essential</tt>; dependencies will
1153 prevent its premature removal, and we need to be able to
1154 remove it when it has been superseded.
1158 Since dpkg will not prevent upgrading of other packages
1159 while an <tt>essential</tt> package is in an unconfigured
1160 state, all <tt>essential</tt> packages must supply all of
1161 their core functionality even when unconfigured. If the
1162 package cannot satisfy this requirement it must not be
1163 tagged as essential, and any packages depending on this
1164 package must instead have explicit dependency fields as
1169 Maintainers should take great care in adding any programs,
1170 interfaces, or functionality to <tt>essential</tt> packages.
1171 Packages may assume that functionality provided by
1172 <tt>essential</tt> packages is always available without
1173 declaring explicit dependencies, which means that removing
1174 functionality from the Essential set is very difficult and is
1175 almost never done. Any capability added to an
1176 <tt>essential</tt> package therefore creates an obligation to
1177 support that capability as part of the Essential set in
1182 You must not tag any packages <tt>essential</tt> before
1183 this has been discussed on the <tt>debian-devel</tt>
1184 mailing list and a consensus about doing that has been
1189 <sect id="maintscripts">
1190 <heading>Maintainer Scripts</heading>
1193 The package installation scripts should avoid producing
1194 output which is unnecessary for the user to see and
1195 should rely on <prgn>dpkg</prgn> to stave off boredom on
1196 the part of a user installing many packages. This means,
1197 amongst other things, using the <tt>--quiet</tt> option on
1198 <prgn>install-info</prgn>.
1202 Errors which occur during the execution of an installation
1203 script must be checked and the installation must not
1204 continue after an error.
1208 Note that in general <ref id="scripts"> applies to package
1209 maintainer scripts, too.
1213 You should not use <prgn>dpkg-divert</prgn> on a file
1214 belonging to another package without consulting the
1215 maintainer of that package first.
1219 All packages which supply an instance of a common command
1220 name (or, in general, filename) should generally use
1221 <prgn>update-alternatives</prgn>, so that they may be
1222 installed together. If <prgn>update-alternatives</prgn>
1223 is not used, then each package must use
1224 <tt>Conflicts</tt> to ensure that other packages are
1225 de-installed. (In this case, it may be appropriate to
1226 specify a conflict against earlier versions of something
1227 that previously did not use
1228 <prgn>update-alternatives</prgn>; this is an exception to
1229 the usual rule that versioned conflicts should be
1233 <sect1 id="maintscriptprompt">
1234 <heading>Prompting in maintainer scripts</heading>
1236 Package maintainer scripts may prompt the user if
1237 necessary. Prompting must be done by communicating
1238 through a program, such as <prgn>debconf</prgn>, which
1239 conforms to the Debian Configuration Management
1240 Specification, version 2 or higher.
1244 Packages which are essential, or which are dependencies of
1245 essential packages, may fall back on another prompting method
1246 if no such interface is available when they are executed.
1250 The Debian Configuration Management Specification is included
1251 in the <file>debconf_specification</file> files in the
1252 <package>debian-policy</package> package.
1253 It is also available from the Debian web mirrors at
1254 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1255 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>.
1259 Packages which use the Debian Configuration Management
1260 Specification may contain an additional
1261 <prgn>config</prgn> script and a <tt>templates</tt>
1262 file in their control archive<footnote>
1263 The control.tar.gz inside the .deb.
1264 See <manref name="deb" section="5">.
1266 The <prgn>config</prgn> script might be run before the
1267 <prgn>preinst</prgn> script, and before the package is unpacked
1268 or any of its dependencies or pre-dependencies are satisfied.
1269 Therefore it must work using only the tools present in
1270 <em>essential</em> packages.<footnote>
1271 <package>Debconf</package> or another tool that
1272 implements the Debian Configuration Management
1273 Specification will also be installed, and any
1274 versioned dependencies on it will be satisfied
1275 before preconfiguration begins.
1280 Packages which use the Debian Configuration Management
1281 Specification must allow for translation of their user-visible
1282 messages by using a gettext-based system such as the one
1283 provided by the <package>po-debconf</package> package.
1287 Packages should try to minimize the amount of prompting
1288 they need to do, and they should ensure that the user
1289 will only ever be asked each question once. This means
1290 that packages should try to use appropriate shared
1291 configuration files (such as <file>/etc/papersize</file> and
1292 <file>/etc/news/server</file>), and shared
1293 <package>debconf</package> variables rather than each
1294 prompting for their own list of required pieces of
1299 It also means that an upgrade should not ask the same
1300 questions again, unless the user has used
1301 <tt>dpkg --purge</tt> to remove the package's configuration.
1302 The answers to configuration questions should be stored in an
1303 appropriate place in <file>/etc</file> so that the user can
1304 modify them, and how this has been done should be
1309 If a package has a vitally important piece of
1310 information to pass to the user (such as "don't run me
1311 as I am, you must edit the following configuration files
1312 first or you risk your system emitting badly-formatted
1313 messages"), it should display this in the
1314 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1315 prompt the user to hit return to acknowledge the
1316 message. Copyright messages do not count as vitally
1317 important (they belong in
1318 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1319 neither do instructions on how to use a program (these
1320 should be in on-line documentation, where all the users
1325 Any necessary prompting should almost always be confined
1326 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1327 script. If it is done in the <prgn>postinst</prgn>, it
1328 should be protected with a conditional so that
1329 unnecessary prompting doesn't happen if a package's
1330 installation fails and the <prgn>postinst</prgn> is
1331 called with <tt>abort-upgrade</tt>,
1332 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1342 <heading>Source packages</heading>
1344 <sect id="standardsversion">
1345 <heading>Standards conformance</heading>
1348 Source packages should specify the most recent version number
1349 of this policy document with which your package complied
1350 when it was last updated.
1354 This information may be used to file bug reports
1355 automatically if your package becomes too much out of date.
1359 The version is specified in the <tt>Standards-Version</tt>
1361 The format of the <tt>Standards-Version</tt> field is
1362 described in <ref id="f-Standards-Version">.
1366 You should regularly, and especially if your package has
1367 become out of date, check for the newest Policy Manual
1368 available and update your package, if necessary. When your
1369 package complies with the new standards you should update the
1370 <tt>Standards-Version</tt> source package field and
1371 release it.<footnote>
1372 See the file <file>upgrading-checklist</file> for
1373 information about policy which has changed between
1374 different versions of this document.
1380 <sect id="pkg-relations">
1381 <heading>Package relationships</heading>
1384 Source packages should specify which binary packages they
1385 require to be installed or not to be installed in order to
1386 build correctly. For example, if building a package
1387 requires a certain compiler, then the compiler should be
1388 specified as a build-time dependency.
1392 It is not necessary to explicitly specify build-time
1393 relationships on a minimal set of packages that are always
1394 needed to compile, link and put in a Debian package a
1395 standard "Hello World!" program written in C or C++. The
1396 required packages are called <em>build-essential</em>, and
1397 an informational list can be found in
1398 <file>/usr/share/doc/build-essential/list</file> (which is
1399 contained in the <tt>build-essential</tt>
1402 <list compact="compact">
1404 This allows maintaining the list separately
1405 from the policy documents (the list does not
1406 need the kind of control that the policy
1410 Having a separate package allows one to install
1411 the build-essential packages on a machine, as
1412 well as allowing other packages such as tasks to
1413 require installation of the build-essential
1414 packages using the depends relation.
1417 The separate package allows bug reports against
1418 the list to be categorized separately from
1419 the policy management process in the BTS.
1426 When specifying the set of build-time dependencies, one
1427 should list only those packages explicitly required by the
1428 build. It is not necessary to list packages which are
1429 required merely because some other package in the list of
1430 build-time dependencies depends on them.<footnote>
1431 The reason for this is that dependencies change, and
1432 you should list all those packages, and <em>only</em>
1433 those packages that <em>you</em> need directly. What
1434 others need is their business. For example, if you
1435 only link against <file>libimlib</file>, you will need to
1436 build-depend on <package>libimlib2-dev</package> but
1437 not against any <tt>libjpeg*</tt> packages, even
1438 though <tt>libimlib2-dev</tt> currently depends on
1439 them: installation of <package>libimlib2-dev</package>
1440 will automatically ensure that all of its run-time
1441 dependencies are satisfied.
1446 If build-time dependencies are specified, it must be
1447 possible to build the package and produce working binaries
1448 on a system with only essential and build-essential
1449 packages installed and also those required to satisfy the
1450 build-time relationships (including any implied
1451 relationships). In particular, this means that version
1452 clauses should be used rigorously in build-time
1453 relationships so that one cannot produce bad or
1454 inconsistently configured packages when the relationships
1455 are properly satisfied.
1459 <ref id="relationships"> explains the technical details.
1464 <heading>Changes to the upstream sources</heading>
1467 If changes to the source code are made that are not
1468 specific to the needs of the Debian system, they should be
1469 sent to the upstream authors in whatever form they prefer
1470 so as to be included in the upstream version of the
1475 If you need to configure the package differently for
1476 Debian or for Linux, and the upstream source doesn't
1477 provide a way to do so, you should add such configuration
1478 facilities (for example, a new <prgn>autoconf</prgn> test
1479 or <tt>#define</tt>) and send the patch to the upstream
1480 authors, with the default set to the way they originally
1481 had it. You can then easily override the default in your
1482 <file>debian/rules</file> or wherever is appropriate.
1486 You should make sure that the <prgn>configure</prgn> utility
1487 detects the correct architecture specification string
1488 (refer to <ref id="arch-spec"> for details).
1492 If you need to edit a <prgn>Makefile</prgn> where GNU-style
1493 <prgn>configure</prgn> scripts are used, you should edit the
1494 <file>.in</file> files rather than editing the
1495 <prgn>Makefile</prgn> directly. This allows the user to
1496 reconfigure the package if necessary. You should
1497 <em>not</em> configure the package and edit the generated
1498 <prgn>Makefile</prgn>! This makes it impossible for someone
1499 else to later reconfigure the package without losing the
1505 <sect id="dpkgchangelog">
1506 <heading>Debian changelog: <file>debian/changelog</file></heading>
1509 Changes in the Debian version of the package should be
1510 briefly explained in the Debian changelog file
1511 <file>debian/changelog</file>.<footnote>
1513 Mistakes in changelogs are usually best rectified by
1514 making a new changelog entry rather than "rewriting
1515 history" by editing old changelog entries.
1518 This includes modifications
1519 made in the Debian package compared to the upstream one
1520 as well as other changes and updates to the package.
1522 Although there is nothing stopping an author who is also
1523 the Debian maintainer from using this changelog for all
1524 their changes, it will have to be renamed if the Debian
1525 and upstream maintainers become different people. In such
1526 a case, however, it might be better to maintain the package
1527 as a non-native package.
1532 The format of the <file>debian/changelog</file> allows the
1533 package building tools to discover which version of the package
1534 is being built and find out other release-specific information.
1538 That format is a series of entries like this:
1540 <example compact="compact">
1541 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1543 [optional blank line(s), stripped]
1545 * <var>change details</var>
1546 <var>more change details</var>
1548 [blank line(s), included in output of dpkg-parsechangelog]
1550 * <var>even more change details</var>
1552 [optional blank line(s), stripped]
1554 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1559 <var>package</var> and <var>version</var> are the source
1560 package name and version number.
1564 <var>distribution(s)</var> lists the distributions where
1565 this version should be installed when it is uploaded - it
1566 is copied to the <tt>Distribution</tt> field in the
1567 <file>.changes</file> file. See <ref id="f-Distribution">.
1571 <var>urgency</var> is the value for the <tt>Urgency</tt>
1572 field in the <file>.changes</file> file for the upload
1573 (see <ref id="f-Urgency">). It is not possible to specify
1574 an urgency containing commas; commas are used to separate
1575 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1576 <prgn>dpkg</prgn> changelog format (though there is
1577 currently only one useful <var>keyword</var>,
1582 The change details may in fact be any series of lines
1583 starting with at least two spaces, but conventionally each
1584 change starts with an asterisk and a separating space and
1585 continuation lines are indented so as to bring them in
1586 line with the start of the text above. Blank lines may be
1587 used here to separate groups of changes, if desired.
1591 If this upload resolves bugs recorded in the Bug Tracking
1592 System (BTS), they may be automatically closed on the
1593 inclusion of this package into the Debian archive by
1594 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1595 in the change details.<footnote>
1596 To be precise, the string should match the following
1597 Perl regular expression:
1599 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1601 Then all of the bug numbers listed will be closed by the
1602 archive maintenance script (<prgn>katie</prgn>) using the
1603 <var>version</var> of the changelog entry.
1605 This information is conveyed via the <tt>Closes</tt> field
1606 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1610 The maintainer name and email address used in the changelog
1611 should be the details of the person uploading <em>this</em>
1612 version. They are <em>not</em> necessarily those of the
1613 usual package maintainer. The information here will be
1614 copied to the <tt>Changed-By</tt> field in the
1615 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1616 and then later used to send an acknowledgement when the
1617 upload has been installed.
1621 The <var>date</var> has the following format<footnote>
1622 This is the same as the format generated by <tt>date
1624 </footnote> (compatible and with the same semantics of
1625 RFC 2822 and RFC 5322):
1626 <example>day-of-week, dd month yyyy hh:mm:ss +zzzz</example>
1628 <list compact="compact">
1630 day-of week is one of: Mon, Tue, Wed, Thu, Fri, Sat, Sun
1633 dd is a one- or two-digit day of the month (01-31)
1636 month is one of: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug,
1639 <item>yyyy is the four-digit year (e.g. 2010)</item>
1640 <item>hh is the two-digit hour (00-23)</item>
1641 <item>mm is the two-digit minutes (00-59)</item>
1642 <item>ss is the two-digit seconds (00-60)</item>
1644 +zzzz or -zzzz is the the time zone offset from Coordinated
1645 Universal Time (UTC). "+" indicates that the time is ahead
1646 of (i.e., east of) UTC and "-" indicates that the time is
1647 behind (i.e., west of) UTC. The first two digits indicate
1648 the hour difference from UTC and the last two digits
1649 indicate the number of additional minutes difference from
1650 UTC. The last two digits must be in the range 00-59.
1656 The first "title" line with the package name must start
1657 at the left hand margin. The "trailer" line with the
1658 maintainer and date details must be preceded by exactly
1659 one space. The maintainer details and the date must be
1660 separated by exactly two spaces.
1664 The entire changelog must be encoded in UTF-8.
1668 For more information on placement of the changelog files
1669 within binary packages, please see <ref id="changelogs">.
1673 <sect id="dpkgcopyright">
1674 <heading>Copyright: <file>debian/copyright</file></heading>
1676 Every package must be accompanied by a verbatim copy of its
1677 copyright information and distribution license in the file
1678 <file>/usr/share/doc/<var>package</var>/copyright</file>
1679 (see <ref id="copyrightfile"> for further details). Also see
1680 <ref id="pkgcopyright"> for further considerations related
1681 to copyrights for packages.
1685 <heading>Error trapping in makefiles</heading>
1688 When <prgn>make</prgn> invokes a command in a makefile
1689 (including your package's upstream makefiles and
1690 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1691 means that <prgn>sh</prgn>'s usual bad error handling
1692 properties apply: if you include a miniature script as one
1693 of the commands in your makefile you'll find that if you
1694 don't do anything about it then errors are not detected
1695 and <prgn>make</prgn> will blithely continue after
1700 Every time you put more than one shell command (this
1701 includes using a loop) in a makefile command you
1702 must make sure that errors are trapped. For
1703 simple compound commands, such as changing directory and
1704 then running a program, using <tt>&&</tt> rather
1705 than semicolon as a command separator is sufficient. For
1706 more complex commands including most loops and
1707 conditionals you should include a separate <tt>set -e</tt>
1708 command at the start of every makefile command that's
1709 actually one of these miniature shell scripts.
1713 <sect id="timestamps">
1714 <heading>Time Stamps</heading>
1716 Maintainers should preserve the modification times of the
1717 upstream source files in a package, as far as is reasonably
1719 The rationale is that there is some information conveyed
1720 by knowing the age of the file, for example, you could
1721 recognize that some documentation is very old by looking
1722 at the modification time, so it would be nice if the
1723 modification time of the upstream source would be
1729 <sect id="restrictions">
1730 <heading>Restrictions on objects in source packages</heading>
1733 The source package may not contain any hard links<footnote>
1735 This is not currently detected when building source
1736 packages, but only when extracting
1740 Hard links may be permitted at some point in the
1741 future, but would require a fair amount of
1744 </footnote>, device special files, sockets or setuid or
1745 setgid files.<footnote>
1746 Setgid directories are allowed.
1751 <sect id="debianrules">
1752 <heading>Main building script: <file>debian/rules</file></heading>
1755 This file must be an executable makefile, and contains the
1756 package-specific recipes for compiling the package and
1757 building binary package(s) from the source.
1761 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1762 so that it can be invoked by saying its name rather than
1763 invoking <prgn>make</prgn> explicitly. That is, invoking
1764 either of <tt>make -f debian/rules <em>args...</em></tt>
1765 or <tt>./debian/rules <em>args...</em></tt> must result in
1770 Since an interactive <file>debian/rules</file> script makes it
1771 impossible to auto-compile that package and also makes it
1772 hard for other people to reproduce the same binary
1773 package, all <em>required targets</em> must be
1774 non-interactive. At a minimum, required targets are the
1775 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1776 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1777 <em>binary-indep</em>, and <em>build</em>. It also follows
1778 that any target that these targets depend on must also be
1783 The targets are as follows (required unless stated otherwise):
1785 <tag><tt>build</tt></tag>
1788 The <tt>build</tt> target should perform all the
1789 configuration and compilation of the package.
1790 If a package has an interactive pre-build
1791 configuration routine, the Debianized source package
1792 must either be built after this has taken place (so
1793 that the binary package can be built without rerunning
1794 the configuration) or the configuration routine
1795 modified to become non-interactive. (The latter is
1796 preferable if there are architecture-specific features
1797 detected by the configuration routine.)
1801 For some packages, notably ones where the same
1802 source tree is compiled in different ways to produce
1803 two binary packages, the <tt>build</tt> target
1804 does not make much sense. For these packages it is
1805 good enough to provide two (or more) targets
1806 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1807 for each of the ways of building the package, and a
1808 <tt>build</tt> target that does nothing. The
1809 <tt>binary</tt> target will have to build the
1810 package in each of the possible ways and make the
1811 binary package out of each.
1815 The <tt>build</tt> target must not do anything
1816 that might require root privilege.
1820 The <tt>build</tt> target may need to run the
1821 <tt>clean</tt> target first - see below.
1825 When a package has a configuration and build routine
1826 which takes a long time, or when the makefiles are
1827 poorly designed, or when <tt>build</tt> needs to
1828 run <tt>clean</tt> first, it is a good idea to
1829 <tt>touch build</tt> when the build process is
1830 complete. This will ensure that if <tt>debian/rules
1831 build</tt> is run again it will not rebuild the whole
1833 Another common way to do this is for <tt>build</tt>
1834 to depend on <prgn>build-stamp</prgn> and to do
1835 nothing else, and for the <prgn>build-stamp</prgn>
1836 target to do the building and to <tt>touch
1837 build-stamp</tt> on completion. This is
1838 especially useful if the build routine creates a
1839 file or directory called <tt>build</tt>; in such a
1840 case, <tt>build</tt> will need to be listed as
1841 a phony target (i.e., as a dependency of the
1842 <tt>.PHONY</tt> target). See the documentation of
1843 <prgn>make</prgn> for more information on phony
1849 <tag><tt>build-arch</tt> (optional),
1850 <tt>build-indep</tt> (optional)
1854 A package may also provide both of the targets
1855 <tt>build-arch</tt> and <tt>build-indep</tt>.
1856 The <tt>build-arch</tt> target, if provided, should
1857 perform all the configuration and compilation required for
1858 producing all architecture-dependant binary packages
1859 (those packages for which the body of the
1860 <tt>Architecture</tt> field in <tt>debian/control</tt> is
1861 not <tt>all</tt>). Similarly, the <tt>build-indep</tt>
1862 target, if provided, should perform all the configuration
1863 and compilation required for producing all
1864 architecture-independent binary packages (those packages
1865 for which the body of the <tt>Architecture</tt> field
1866 in <tt>debian/control</tt> is <tt>all</tt>).
1867 The <tt>build</tt> target should depend on those of the
1868 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1869 are provided in the rules file.<footnote>
1870 The intent of this split is so that binary-only builds
1871 need not install the dependencies required for
1872 the <tt>build-indep</tt> target. However, this is not
1873 yet used in practice since <tt>dpkg-buildpackage
1874 -B</tt>, and therefore the autobuilders,
1875 invoke <tt>build</tt> rather than <tt>build-arch</tt>
1876 due to the difficulties in determining whether the
1877 optional <tt>build-arch</tt> target exists.
1882 If one or both of the targets <tt>build-arch</tt> and
1883 <tt>build-indep</tt> are not provided, then invoking
1884 <file>debian/rules</file> with one of the not-provided
1885 targets as arguments should produce a exit status code
1886 of 2. Usually this is provided automatically by make
1887 if the target is missing.
1891 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1892 must not do anything that might require root privilege.
1896 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1897 <tt>binary-indep</tt>
1901 The <tt>binary</tt> target must be all that is
1902 necessary for the user to build the binary package(s)
1903 produced from this source package. It is
1904 split into two parts: <prgn>binary-arch</prgn> builds
1905 the binary packages which are specific to a particular
1906 architecture, and <tt>binary-indep</tt> builds
1907 those which are not.
1910 <tt>binary</tt> may be (and commonly is) a target with
1911 no commands which simply depends on
1912 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1915 Both <tt>binary-*</tt> targets should depend on the
1916 <tt>build</tt> target, or on the appropriate
1917 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1918 provided, so that the package is built if it has not
1919 been already. It should then create the relevant
1920 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1921 make their control files and <prgn>dpkg-deb</prgn> to
1922 build them and place them in the parent of the top
1927 Both the <tt>binary-arch</tt> and
1928 <tt>binary-indep</tt> targets <em>must</em> exist.
1929 If one of them has nothing to do (which will always be
1930 the case if the source generates only a single binary
1931 package, whether architecture-dependent or not), it
1932 must still exist and must always succeed.
1936 The <tt>binary</tt> targets must be invoked as
1938 The <prgn>fakeroot</prgn> package often allows one
1939 to build a package correctly even without being
1945 <tag><tt>clean</tt></tag>
1948 This must undo any effects that the <tt>build</tt>
1949 and <tt>binary</tt> targets may have had, except
1950 that it should leave alone any output files created in
1951 the parent directory by a run of a <tt>binary</tt>
1956 If a <tt>build</tt> file is touched at the end of
1957 the <tt>build</tt> target, as suggested above, it
1958 should be removed as the first action that
1959 <tt>clean</tt> performs, so that running
1960 <tt>build</tt> again after an interrupted
1961 <tt>clean</tt> doesn't think that everything is
1966 The <tt>clean</tt> target may need to be
1967 invoked as root if <tt>binary</tt> has been
1968 invoked since the last <tt>clean</tt>, or if
1969 <tt>build</tt> has been invoked as root (since
1970 <tt>build</tt> may create directories, for
1975 <tag><tt>get-orig-source</tt> (optional)</tag>
1978 This target fetches the most recent version of the
1979 original source package from a canonical archive site
1980 (via FTP or WWW, for example), does any necessary
1981 rearrangement to turn it into the original source
1982 tar file format described below, and leaves it in the
1987 This target may be invoked in any directory, and
1988 should take care to clean up any temporary files it
1993 This target is optional, but providing it if
1994 possible is a good idea.
1998 <tag><tt>patch</tt> (optional)</tag>
2001 This target performs whatever additional actions are
2002 required to make the source ready for editing (unpacking
2003 additional upstream archives, applying patches, etc.).
2004 It is recommended to be implemented for any package where
2005 <tt>dpkg-source -x</tt> does not result in source ready
2006 for additional modification. See
2007 <ref id="readmesource">.
2013 The <tt>build</tt>, <tt>binary</tt> and
2014 <tt>clean</tt> targets must be invoked with the current
2015 directory being the package's top-level directory.
2020 Additional targets may exist in <file>debian/rules</file>,
2021 either as published or undocumented interfaces or for the
2022 package's internal use.
2026 The architectures we build on and build for are determined
2027 by <prgn>make</prgn> variables using the utility
2028 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
2029 You can determine the
2030 Debian architecture and the GNU style architecture
2031 specification string for the build machine (the machine type
2032 we are building on) as well as for the host machine (the
2033 machine type we are building for). Here is a list of
2034 supported <prgn>make</prgn> variables:
2035 <list compact="compact">
2037 <tt>DEB_*_ARCH</tt> (the Debian architecture)
2040 <tt>DEB_*_ARCH_CPU</tt> (the Debian CPU name)
2043 <tt>DEB_*_ARCH_OS</tt> (the Debian System name)
2046 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2047 specification string)
2050 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2051 <tt>DEB_*_GNU_TYPE</tt>)
2054 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2055 <tt>DEB_*_GNU_TYPE</tt>)
2057 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2058 the build machine or <tt>HOST</tt> for specification of the
2063 Backward compatibility can be provided in the rules file
2064 by setting the needed variables to suitable default
2065 values; please refer to the documentation of
2066 <prgn>dpkg-architecture</prgn> for details.
2070 It is important to understand that the <tt>DEB_*_ARCH</tt>
2071 string only determines which Debian architecture we are
2072 building on or for. It should not be used to get the CPU
2073 or system information; the <tt>DEB_*_ARCH_CPU</tt> and
2074 <tt>DEB_*_ARCH_OS</tt> variables should be used for that.
2075 GNU style variables should generally only be used with upstream
2079 <sect1 id="debianrules-options">
2080 <heading><file>debian/rules</file> and
2081 <tt>DEB_BUILD_OPTIONS</tt></heading>
2084 Supporting the standardized environment variable
2085 <tt>DEB_BUILD_OPTIONS</tt> is recommended. This variable can
2086 contain several flags to change how a package is compiled and
2087 built. Each flag must be in the form <var>flag</var> or
2088 <var>flag</var>=<var>options</var>. If multiple flags are
2089 given, they must be separated by whitespace.<footnote>
2090 Some packages support any delimiter, but whitespace is the
2091 easiest to parse inside a makefile and avoids ambiguity with
2092 flag values that contain commas.
2094 <var>flag</var> must start with a lowercase letter
2095 (<tt>a-z</tt>) and consist only of lowercase letters,
2096 numbers (<tt>0-9</tt>), and the characters
2097 <tt>-</tt> and <tt>_</tt> (hyphen and underscore).
2098 <var>options</var> must not contain whitespace. The same
2099 tag should not be given multiple times with conflicting
2100 values. Package maintainers may assume that
2101 <tt>DEB_BUILD_OPTIONS</tt> will not contain conflicting tags.
2105 The meaning of the following tags has been standardized:
2109 This tag says to not run any build-time test suite
2110 provided by the package.
2114 The presence of this tag means that the package should
2115 be compiled with a minimum of optimization. For C
2116 programs, it is best to add <tt>-O0</tt> to
2117 <tt>CFLAGS</tt> (although this is usually the default).
2118 Some programs might fail to build or run at this level
2119 of optimization; it may be necessary to use
2120 <tt>-O1</tt>, for example.
2124 This tag means that the debugging symbols should not be
2125 stripped from the binary during installation, so that
2126 debugging information may be included in the package.
2128 <tag>parallel=n</tag>
2130 This tag means that the package should be built using up
2131 to <tt>n</tt> parallel processes if the package build
2132 system supports this.<footnote>
2133 Packages built with <tt>make</tt> can often implement
2134 this by passing the <tt>-j</tt><var>n</var> option to
2137 If the package build system does not support parallel
2138 builds, this string must be ignored. If the package
2139 build system only supports a lower level of concurrency
2140 than <var>n</var>, the package should be built using as
2141 many parallel processes as the package build system
2142 supports. It is up to the package maintainer to decide
2143 whether the package build times are long enough and the
2144 package build system is robust enough to make supporting
2145 parallel builds worthwhile.
2151 Unknown flags must be ignored by <file>debian/rules</file>.
2155 The following makefile snippet is an example of how one may
2156 implement the build options; you will probably have to
2157 massage this example in order to make it work for your
2159 <example compact="compact">
2162 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
2163 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
2164 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
2165 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
2167 ifneq (,$(filter noopt,$(DEB_BUILD_OPTIONS)))
2172 ifeq (,$(filter nostrip,$(DEB_BUILD_OPTIONS)))
2173 INSTALL_PROGRAM += -s
2175 ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2176 NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2177 MAKEFLAGS += -j$(NUMJOBS)
2182 ifeq (,$(filter nocheck,$(DEB_BUILD_OPTIONS)))
2183 # Code to run the package test suite.
2190 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2191 <sect id="substvars">
2192 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2195 When <prgn>dpkg-gencontrol</prgn>,
2196 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2197 generate control files they perform variable substitutions
2198 on their output just before writing it. Variable
2199 substitutions have the form <tt>${<var>variable</var>}</tt>.
2200 The optional file <file>debian/substvars</file> contains
2201 variable substitutions to be used; variables can also be set
2202 directly from <file>debian/rules</file> using the <tt>-V</tt>
2203 option to the source packaging commands, and certain
2204 predefined variables are also available.
2208 The <file>debian/substvars</file> file is usually generated and
2209 modified dynamically by <file>debian/rules</file> targets, in
2210 which case it must be removed by the <tt>clean</tt> target.
2214 See <manref name="deb-substvars" section="5"> for full
2215 details about source variable substitutions, including the
2216 format of <file>debian/substvars</file>.</p>
2219 <sect id="debianwatch">
2220 <heading>Optional upstream source location: <file>debian/watch</file></heading>
2223 This is an optional, recommended control file for the
2224 <tt>uscan</tt> utility which defines how to automatically
2225 scan ftp or http sites for newly available updates of the
2226 package. This is used by <url id="
2227 http://dehs.alioth.debian.org/"> and other Debian QA tools
2228 to help with quality control and maintenance of the
2229 distribution as a whole.
2234 <sect id="debianfiles">
2235 <heading>Generated files list: <file>debian/files</file></heading>
2238 This file is not a permanent part of the source tree; it
2239 is used while building packages to record which files are
2240 being generated. <prgn>dpkg-genchanges</prgn> uses it
2241 when it generates a <file>.changes</file> file.
2245 It should not exist in a shipped source package, and so it
2246 (and any backup files or temporary files such as
2247 <file>files.new</file><footnote>
2248 <file>files.new</file> is used as a temporary file by
2249 <prgn>dpkg-gencontrol</prgn> and
2250 <prgn>dpkg-distaddfile</prgn> - they write a new
2251 version of <tt>files</tt> here before renaming it,
2252 to avoid leaving a corrupted copy if an error
2254 </footnote>) should be removed by the
2255 <tt>clean</tt> target. It may also be wise to
2256 ensure a fresh start by emptying or removing it at the
2257 start of the <tt>binary</tt> target.
2261 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2262 package, it adds an entry to <file>debian/files</file> for the
2263 <file>.deb</file> file that will be created when <tt>dpkg-deb
2264 --build</tt> is run for that binary package. So for most
2265 packages all that needs to be done with this file is to
2266 delete it in the <tt>clean</tt> target.
2270 If a package upload includes files besides the source
2271 package and any binary packages whose control files were
2272 made with <prgn>dpkg-gencontrol</prgn> then they should be
2273 placed in the parent of the package's top-level directory
2274 and <prgn>dpkg-distaddfile</prgn> should be called to add
2275 the file to the list in <file>debian/files</file>.</p>
2278 <sect id="embeddedfiles">
2279 <heading>Convenience copies of code</heading>
2282 Some software packages include in their distribution convenience
2283 copies of code from other software packages, generally so that
2284 users compiling from source don't have to download multiple
2285 packages. Debian packages should not make use of these
2286 convenience copies unless the included package is explicitly
2287 intended to be used in this way.<footnote>
2288 For example, parts of the GNU build system work like this.
2290 If the included code is already in the Debian archive in the
2291 form of a library, the Debian packaging should ensure that
2292 binary packages reference the libraries already in Debian and
2293 the convenience copy is not used. If the included code is not
2294 already in Debian, it should be packaged separately as a
2295 prerequisite if possible.
2297 Having multiple copies of the same code in Debian is
2298 inefficient, often creates either static linking or shared
2299 library conflicts, and, most importantly, increases the
2300 difficulty of handling security vulnerabilities in the
2306 <sect id="readmesource">
2307 <heading>Source package handling:
2308 <file>debian/README.source</file></heading>
2311 If running <prgn>dpkg-source -x</prgn> on a source package
2312 doesn't produce the source of the package, ready for editing,
2313 and allow one to make changes and run
2314 <prgn>dpkg-buildpackage</prgn> to produce a modified package
2315 without taking any additional steps, creating a
2316 <file>debian/README.source</file> documentation file is
2317 recommended. This file should explain how to do all of the
2320 <item>Generate the fully patched source, in a form ready for
2321 editing, that would be built to create Debian
2322 packages. Doing this with a <tt>patch</tt> target in
2323 <file>debian/rules</file> is recommended; see
2324 <ref id="debianrules">.</item>
2325 <item>Modify the source and save those modifications so that
2326 they will be applied when building the package.</item>
2327 <item>Remove source modifications that are currently being
2328 applied when building the package.</item>
2329 <item>Optionally, document what steps are necessary to
2330 upgrade the Debian source package to a new upstream version,
2331 if applicable.</item>
2333 This explanation should include specific commands and mention
2334 any additional required Debian packages. It should not assume
2335 familiarity with any specific Debian packaging system or patch
2340 This explanation may refer to a documentation file installed by
2341 one of the package's build dependencies provided that the
2342 referenced documentation clearly explains these tasks and is not
2343 a general reference manual.
2347 <file>debian/README.source</file> may also include any other
2348 information that would be helpful to someone modifying the
2349 source package. Even if the package doesn't fit the above
2350 description, maintainers are encouraged to document in a
2351 <file>debian/README.source</file> file any source package with a
2352 particularly complex or unintuitive source layout or build
2353 system (for example, a package that builds the same source
2354 multiple times to generate different binary packages).
2360 <chapt id="controlfields">
2361 <heading>Control files and their fields</heading>
2364 The package management system manipulates data represented in
2365 a common format, known as <em>control data</em>, stored in
2366 <em>control files</em>.
2367 Control files are used for source packages, binary packages and
2368 the <file>.changes</file> files which control the installation
2369 of uploaded files<footnote>
2370 <prgn>dpkg</prgn>'s internal databases are in a similar
2375 <sect id="controlsyntax">
2376 <heading>Syntax of control files</heading>
2379 A control file consists of one or more paragraphs of
2381 The paragraphs are also sometimes referred to as stanzas.
2383 The paragraphs are separated by blank lines. Some control
2384 files allow only one paragraph; others allow several, in
2385 which case each paragraph usually refers to a different
2386 package. (For example, in source packages, the first
2387 paragraph refers to the source package, and later paragraphs
2388 refer to binary packages generated from the source.)
2392 Each paragraph consists of a series of data fields; each
2393 field consists of the field name, followed by a colon and
2394 then the data/value associated with that field. It ends at
2395 the end of the (logical) line. Horizontal whitespace
2396 (spaces and tabs) may occur immediately before or after the
2397 value and is ignored there; it is conventional to put a
2398 single space after the colon. For example, a field might
2400 <example compact="compact">
2403 the field name is <tt>Package</tt> and the field value
2408 A paragraph must not contain more than one instance of a
2409 particular field name.
2413 Many fields' values may span several lines; in this case
2414 each continuation line must start with a space or a tab.
2415 Any trailing spaces or tabs at the end of individual
2416 lines of a field value are ignored.
2420 In fields where it is specified that lines may not wrap,
2421 only a single line of data is allowed and whitespace is not
2422 significant in a field body. Whitespace must not appear
2423 inside names (of packages, architectures, files or anything
2424 else) or version numbers, or between the characters of
2425 multi-character version relationships.
2429 Field names are not case-sensitive, but it is usual to
2430 capitalize the field names using mixed case as shown below.
2431 Field values are case-sensitive unless the description of the
2432 field says otherwise.
2436 Blank lines, or lines consisting only of spaces and tabs,
2437 are not allowed within field values or between fields - that
2438 would mean a new paragraph.
2442 All control files must be encoded in UTF-8.
2446 <sect id="sourcecontrolfiles">
2447 <heading>Source package control files -- <file>debian/control</file></heading>
2450 The <file>debian/control</file> file contains the most vital
2451 (and version-independent) information about the source package
2452 and about the binary packages it creates.
2456 The first paragraph of the control file contains information about
2457 the source package in general. The subsequent sets each describe a
2458 binary package that the source tree builds.
2462 The fields in the general paragraph (the first one, for the source
2465 <list compact="compact">
2466 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2467 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2468 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2469 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2470 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2471 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2472 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2473 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2478 The fields in the binary package paragraphs are:
2480 <list compact="compact">
2481 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2482 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2483 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2484 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2485 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2486 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2487 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2488 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2493 The syntax and semantics of the fields are described below.
2497 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2498 generate control files for binary packages (see below), by
2499 <prgn>dpkg-genchanges</prgn> to generate the
2500 <tt>.changes</tt> file to accompany the upload, and by
2501 <prgn>dpkg-source</prgn> when it creates the
2502 <file>.dsc</file> source control file as part of a source
2503 archive. Many fields are permitted to span multiple lines in
2504 <file>debian/control</file> but not in any other control
2505 file. These tools are responsible for removing the line
2506 breaks from such fields when using fields from
2507 <file>debian/control</file> to generate other control files.
2511 The fields here may contain variable references - their
2512 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2513 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2514 when they generate output control files.
2515 See <ref id="substvars"> for details.
2519 In addition to the control file syntax described <qref
2520 id="controlsyntax">above</qref>, this file may also contain
2521 comment lines starting with <tt>#</tt> without any preceding
2522 whitespace. All such lines are ignored, even in the middle of
2523 continuation lines for a multiline field, and do not end a
2529 <sect id="binarycontrolfiles">
2530 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2533 The <file>DEBIAN/control</file> file contains the most vital
2534 (and version-dependent) information about a binary package.
2538 The fields in this file are:
2540 <list compact="compact">
2541 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2542 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2543 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2544 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2545 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2546 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2547 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2548 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2549 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2550 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2551 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2552 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2557 <sect id="debiansourcecontrolfiles">
2558 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2561 This file contains a series of fields, identified and
2562 separated just like the fields in the control file of
2563 a binary package. The fields are listed below; their
2564 syntax is described above, in <ref id="pkg-controlfields">.
2566 <list compact="compact">
2567 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2568 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2569 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2570 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2571 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2572 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2573 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2574 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2575 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2576 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2577 <item><qref id="f-Checksums"><tt>Checksums-Sha1</tt>
2578 and <tt>Checksums-Sha256</tt> (recommended)</item>
2579 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2584 The source package control file is generated by
2585 <prgn>dpkg-source</prgn> when it builds the source
2586 archive, from other files in the source package,
2587 described above. When unpacking, it is checked against
2588 the files and directories in the other parts of the
2594 <sect id="debianchangesfiles">
2595 <heading>Debian changes files -- <file>.changes</file></heading>
2598 The .changes files are used by the Debian archive maintenance
2599 software to process updates to packages. They contain one
2600 paragraph which contains information from the
2601 <tt>debian/control</tt> file and other data about the
2602 source package gathered via <tt>debian/changelog</tt>
2603 and <tt>debian/rules</tt>.
2607 The fields in this file are:
2609 <list compact="compact">
2610 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2611 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2612 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2613 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2614 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2615 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2616 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2617 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2618 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2619 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2620 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2621 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2622 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2623 <item><qref id="f-Checksums"><tt>Checksums-Sha1</tt>
2624 and <tt>Checksums-Sha256</tt> (recommended)</item>
2625 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2630 <sect id="controlfieldslist">
2631 <heading>List of fields</heading>
2633 <sect1 id="f-Source">
2634 <heading><tt>Source</tt></heading>
2637 This field identifies the source package name.
2641 In <file>debian/control</file> or a <file>.dsc</file> file,
2642 this field must contain only the name of the source package.
2646 In a binary package control file or a <file>.changes</file>
2647 file, the source package name may be followed by a version
2648 number in parentheses<footnote>
2649 It is customary to leave a space after the package name
2650 if a version number is specified.
2652 This version number may be omitted (and is, by
2653 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2654 the <tt>Version</tt> field of the binary package in
2655 question. The field itself may be omitted from a binary
2656 package control file when the source package has the same
2657 name and version as the binary package.
2661 Package names (both source and binary,
2662 see <ref id="f-Package">) must consist only of lower case
2663 letters (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus
2664 (<tt>+</tt>) and minus (<tt>-</tt>) signs, and periods
2665 (<tt>.</tt>). They must be at least two characters long and
2666 must start with an alphanumeric character.
2670 <sect1 id="f-Maintainer">
2671 <heading><tt>Maintainer</tt></heading>
2674 The package maintainer's name and email address. The name
2675 must come first, then the email address inside angle
2676 brackets <tt><></tt> (in RFC822 format).
2680 If the maintainer's name contains a full stop then the
2681 whole field will not work directly as an email address due
2682 to a misfeature in the syntax specified in RFC822; a
2683 program using this field as an address must check for this
2684 and correct the problem if necessary (for example by
2685 putting the name in round brackets and moving it to the
2686 end, and bringing the email address forward).
2690 <sect1 id="f-Uploaders">
2691 <heading><tt>Uploaders</tt></heading>
2694 List of the names and email addresses of co-maintainers of
2695 the package, if any. If the package has other maintainers
2696 beside the one named in the
2697 <qref id="f-Maintainer">Maintainer field</qref>, their names
2698 and email addresses should be listed here. The format of each
2699 entry is the same as that of the Maintainer field, and
2700 multiple entries must be comma separated. This is an optional
2705 Any parser that interprets the Uploaders field in
2706 <file>debian/control</file> must permit it to span multiple
2707 lines. Line breaks in an Uploaders field that spans multiple
2708 lines are not significant and the semantics of the field are
2709 the same as if the line breaks had not been present.
2713 <sect1 id="f-Changed-By">
2714 <heading><tt>Changed-By</tt></heading>
2717 The name and email address of the person who prepared this
2718 version of the package, usually a maintainer. The syntax is
2719 the same as for the <qref id="f-Maintainer">Maintainer
2724 <sect1 id="f-Section">
2725 <heading><tt>Section</tt></heading>
2728 This field specifies an application area into which the package
2729 has been classified. See <ref id="subsections">.
2733 When it appears in the <file>debian/control</file> file,
2734 it gives the value for the subfield of the same name in
2735 the <tt>Files</tt> field of the <file>.changes</file> file.
2736 It also gives the default for the same field in the binary
2741 <sect1 id="f-Priority">
2742 <heading><tt>Priority</tt></heading>
2745 This field represents how important it is that the user
2746 have the package installed. See <ref id="priorities">.
2750 When it appears in the <file>debian/control</file> file,
2751 it gives the value for the subfield of the same name in
2752 the <tt>Files</tt> field of the <file>.changes</file> file.
2753 It also gives the default for the same field in the binary
2758 <sect1 id="f-Package">
2759 <heading><tt>Package</tt></heading>
2762 The name of the binary package.
2766 Binary package names must follow the same syntax and
2767 restrictions as source package names. See <ref id="f-Source">
2772 <sect1 id="f-Architecture">
2773 <heading><tt>Architecture</tt></heading>
2776 Depending on context and the control file used, the
2777 <tt>Architecture</tt> field can include the following sets of
2781 A unique single word identifying a Debian machine
2782 architecture as described in <ref id="arch-spec">.
2785 An architecture wildcard identifying a set of Debian
2786 machine architectures, see <ref id="arch-wildcard-spec">.
2787 <tt>any</tt> matches all Debian machine architectures
2788 and is the most frequently used.
2791 <tt>all</tt>, which indicates an
2792 architecture-independent package.
2795 <tt>source</tt>, which indicates a source package.
2801 In the main <file>debian/control</file> file in the source
2802 package, this field may contain the special
2803 value <tt>all</tt>, the special architecture
2804 wildcard <tt>any</tt>, or a list of specific and wildcard
2805 architectures separated by spaces. If <tt>all</tt>
2806 or <tt>any</tt> appears, that value must be the entire
2807 contents of the field. Most packages will use
2808 either <tt>all</tt> or <tt>any</tt>.
2812 Specifying a specific list of architectures indicates that the
2813 source will build an architecture-dependent package only on
2814 architectures included in the list. Specifying a list of
2815 architecture wildcards indicates that the source will build an
2816 architecture-dependent package on only those architectures
2817 that match any of the specified architecture wildcards.
2818 Specifying a list of architectures or architecture wildcards
2819 other than <tt>any</tt> is for the minority of cases where a
2820 program is not portable or is not useful on some
2821 architectures. Where possible, the program should be made
2826 In the source package control file <file>.dsc</file>, this
2827 field may contain either the architecture
2828 wildcard <tt>any</tt> or a list of architectures and
2829 architecture wildcards separated by spaces. If a list is
2830 given, it may include (or consist solely of) the special
2831 value <tt>all</tt>. In other words, in <file>.dsc</file>
2832 files unlike the <file>debian/control</file>, <tt>all</tt> may
2833 occur in combination with specific architectures.
2834 The <tt>Architecture</tt> field in the source package control
2835 file <file>.dsc</file> is generally constructed from
2836 the <tt>Architecture</tt> fields in
2837 the <file>debian/control</file> in the source package.
2841 Specifying <tt>any</tt> indicates that the source package
2842 isn't dependent on any particular architecture and should
2843 compile fine on any one. The produced binary package(s)
2844 will either be specific to whatever the current build
2845 architecture is or will be architecture-independent.
2849 Specifying only <tt>all</tt> indicates that the source package
2850 will only build architecture-independent packages. If this is
2851 the case, <tt>all</tt> must be used rather than <tt>any</tt>;
2852 <tt>any</tt> implies that the source package will build at
2853 least one architecture-dependent package.
2857 Specifying a list of architectures or architecture wildcards
2858 indicates that the source will build an architecture-dependent
2859 package, and will only work correctly on the listed or
2860 matching architectures. If the source package also builds at
2861 least one architecture-independent package, <tt>all</tt> will
2862 also be included in the list.
2866 In a <file>.changes</file> file, the <tt>Architecture</tt>
2867 field lists the architecture(s) of the package(s) currently
2868 being uploaded. This will be a list; if the source for the
2869 package is also being uploaded, the special
2870 entry <tt>source</tt> is also present. <tt>all</tt> will be
2871 present if any architecture-independent packages are being
2872 uploaded. Architecture wildcards such as <tt>any</tt> must
2873 never occur in the <tt>Architecture</tt> field in
2874 the <file>.changes</file> file.
2878 See <ref id="debianrules"> for information on how to get
2879 the architecture for the build process.
2883 <sect1 id="f-Essential">
2884 <heading><tt>Essential</tt></heading>
2887 This is a boolean field which may occur only in the
2888 control file of a binary package or in a per-package fields
2889 paragraph of a main source control data file.
2893 If set to <tt>yes</tt> then the package management system
2894 will refuse to remove the package (upgrading and replacing
2895 it is still possible). The other possible value is <tt>no</tt>,
2896 which is the same as not having the field at all.
2901 <heading>Package interrelationship fields:
2902 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2903 <tt>Recommends</tt>, <tt>Suggests</tt>,
2904 <tt>Breaks</tt>, <tt>Conflicts</tt>,
2905 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2909 These fields describe the package's relationships with
2910 other packages. Their syntax and semantics are described
2911 in <ref id="relationships">.</p>
2914 <sect1 id="f-Standards-Version">
2915 <heading><tt>Standards-Version</tt></heading>
2918 The most recent version of the standards (the policy
2919 manual and associated texts) with which the package
2924 The version number has four components: major and minor
2925 version number and major and minor patch level. When the
2926 standards change in a way that requires every package to
2927 change the major number will be changed. Significant
2928 changes that will require work in many packages will be
2929 signaled by a change to the minor number. The major patch
2930 level will be changed for any change to the meaning of the
2931 standards, however small; the minor patch level will be
2932 changed when only cosmetic, typographical or other edits
2933 are made which neither change the meaning of the document
2934 nor affect the contents of packages.
2938 Thus only the first three components of the policy version
2939 are significant in the <em>Standards-Version</em> control
2940 field, and so either these three components or all four
2941 components may be specified.<footnote>
2942 In the past, people specified the full version number
2943 in the Standards-Version field, for example "2.3.0.0".
2944 Since minor patch-level changes don't introduce new
2945 policy, it was thought it would be better to relax
2946 policy and only require the first 3 components to be
2947 specified, in this example "2.3.0". All four
2948 components may still be used if someone wishes to do so.
2954 <sect1 id="f-Version">
2955 <heading><tt>Version</tt></heading>
2958 The version number of a package. The format is:
2959 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2963 The three components here are:
2965 <tag><var>epoch</var></tag>
2968 This is a single (generally small) unsigned integer. It
2969 may be omitted, in which case zero is assumed. If it is
2970 omitted then the <var>upstream_version</var> may not
2975 It is provided to allow mistakes in the version numbers
2976 of older versions of a package, and also a package's
2977 previous version numbering schemes, to be left behind.
2981 <tag><var>upstream_version</var></tag>
2984 This is the main part of the version number. It is
2985 usually the version number of the original ("upstream")
2986 package from which the <file>.deb</file> file has been made,
2987 if this is applicable. Usually this will be in the same
2988 format as that specified by the upstream author(s);
2989 however, it may need to be reformatted to fit into the
2990 package management system's format and comparison
2995 The comparison behavior of the package management system
2996 with respect to the <var>upstream_version</var> is
2997 described below. The <var>upstream_version</var>
2998 portion of the version number is mandatory.
3002 The <var>upstream_version</var> may contain only
3003 alphanumerics<footnote>
3004 Alphanumerics are <tt>A-Za-z0-9</tt> only.
3006 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
3007 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
3008 tilde) and should start with a digit. If there is no
3009 <var>debian_revision</var> then hyphens are not allowed;
3010 if there is no <var>epoch</var> then colons are not
3015 <tag><var>debian_revision</var></tag>
3018 This part of the version number specifies the version of
3019 the Debian package based on the upstream version. It
3020 may contain only alphanumerics and the characters
3021 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
3022 tilde) and is compared in the same way as the
3023 <var>upstream_version</var> is.
3027 It is optional; if it isn't present then the
3028 <var>upstream_version</var> may not contain a hyphen.
3029 This format represents the case where a piece of
3030 software was written specifically to be turned into a
3031 Debian package, and so there is only one "debianisation"
3032 of it and therefore no revision indication is required.
3036 It is conventional to restart the
3037 <var>debian_revision</var> at <tt>1</tt> each time the
3038 <var>upstream_version</var> is increased.
3042 The package management system will break the version
3043 number apart at the last hyphen in the string (if there
3044 is one) to determine the <var>upstream_version</var> and
3045 <var>debian_revision</var>. The absence of a
3046 <var>debian_revision</var> is equivalent to a
3047 <var>debian_revision</var> of <tt>0</tt>.
3054 When comparing two version numbers, first the <var>epoch</var>
3055 of each are compared, then the <var>upstream_version</var> if
3056 <var>epoch</var> is equal, and then <var>debian_revision</var>
3057 if <var>upstream_version</var> is also equal.
3058 <var>epoch</var> is compared numerically. The
3059 <var>upstream_version</var> and <var>debian_revision</var>
3060 parts are compared by the package management system using the
3061 following algorithm:
3065 The strings are compared from left to right.
3069 First the initial part of each string consisting entirely of
3070 non-digit characters is determined. These two parts (one of
3071 which may be empty) are compared lexically. If a difference
3072 is found it is returned. The lexical comparison is a
3073 comparison of ASCII values modified so that all the letters
3074 sort earlier than all the non-letters and so that a tilde
3075 sorts before anything, even the end of a part. For example,
3076 the following parts are in sorted order from earliest to
3077 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
3078 <tt>a</tt>.<footnote>
3079 One common use of <tt>~</tt> is for upstream pre-releases.
3080 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
3081 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
3086 Then the initial part of the remainder of each string which
3087 consists entirely of digit characters is determined. The
3088 numerical values of these two parts are compared, and any
3089 difference found is returned as the result of the comparison.
3090 For these purposes an empty string (which can only occur at
3091 the end of one or both version strings being compared) counts
3096 These two steps (comparing and removing initial non-digit
3097 strings and initial digit strings) are repeated until a
3098 difference is found or both strings are exhausted.
3102 Note that the purpose of epochs is to allow us to leave behind
3103 mistakes in version numbering, and to cope with situations
3104 where the version numbering scheme changes. It is
3105 <em>not</em> intended to cope with version numbers containing
3106 strings of letters which the package management system cannot
3107 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
3108 silly orderings.<footnote>
3109 The author of this manual has heard of a package whose
3110 versions went <tt>1.1</tt>, <tt>1.2</tt>, <tt>1.3</tt>,
3111 <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>, <tt>2</tt> and so
3117 <sect1 id="f-Description">
3118 <heading><tt>Description</tt></heading>
3121 In a source or binary control file, the <tt>Description</tt>
3122 field contains a description of the binary package, consisting
3123 of two parts, the synopsis or the short description, and the
3124 long description. The field's format is as follows:
3129 Description: <single line synopsis>
3130 <extended description over several lines>
3135 The lines in the extended description can have these formats:
3141 Those starting with a single space are part of a paragraph.
3142 Successive lines of this form will be word-wrapped when
3143 displayed. The leading space will usually be stripped off.
3147 Those starting with two or more spaces. These will be
3148 displayed verbatim. If the display cannot be panned
3149 horizontally, the displaying program will line wrap them "hard"
3150 (i.e., without taking account of word breaks). If it can they
3151 will be allowed to trail off to the right. None, one or two
3152 initial spaces may be deleted, but the number of spaces
3153 deleted from each line will be the same (so that you can have
3154 indenting work correctly, for example).
3158 Those containing a single space followed by a single full stop
3159 character. These are rendered as blank lines. This is the
3160 <em>only</em> way to get a blank line<footnote>
3161 Completely empty lines will not be rendered as blank lines.
3162 Instead, they will cause the parser to think you're starting
3163 a whole new record in the control file, and will therefore
3164 likely abort with an error.
3169 Those containing a space, a full stop and some more characters.
3170 These are for future expansion. Do not use them.
3176 Do not use tab characters. Their effect is not predictable.
3180 See <ref id="descriptions"> for further information on this.
3184 In a <file>.changes</file> file, the <tt>Description</tt>
3185 field contains a summary of the descriptions for the packages
3186 being uploaded. For this case, the first line of the field
3187 value (the part on the same line as <tt>Description:</tt>) is
3188 always empty. The content of the field is expressed as
3189 continuation lines, one line per package. Each line is
3190 indented by one space and contains the name of a binary
3191 package, a space, a hyphen (<tt>-</tt>), a space, and the
3192 short description line from that package.
3196 <sect1 id="f-Distribution">
3197 <heading><tt>Distribution</tt></heading>
3200 In a <file>.changes</file> file or parsed changelog output
3201 this contains the (space-separated) name(s) of the
3202 distribution(s) where this version of the package should
3203 be installed. Valid distributions are determined by the
3204 archive maintainers.<footnote>
3205 Example distribution names in the Debian archive used in
3206 <file>.changes</file> files are:
3207 <taglist compact="compact">
3208 <tag><em>unstable</em></tag>
3210 This distribution value refers to the
3211 <em>developmental</em> part of the Debian distribution
3212 tree. Most new packages, new upstream versions of
3213 packages and bug fixes go into the <em>unstable</em>
3217 <tag><em>experimental</em></tag>
3219 The packages with this distribution value are deemed
3220 by their maintainers to be high risk. Oftentimes they
3221 represent early beta or developmental packages from
3222 various sources that the maintainers want people to
3223 try, but are not ready to be a part of the other parts
3224 of the Debian distribution tree.
3229 Others are used for updating stable releases or for
3230 security uploads. More information is available in the
3231 Debian Developer's Reference, section "The Debian
3235 The Debian archive software only supports listing a single
3236 distribution. Migration of packages to other distributions is
3237 handled outside of the upload process.
3242 <heading><tt>Date</tt></heading>
3245 This field includes the date the package was built or last
3246 edited. It must be in the same format as the <var>date</var>
3247 in a <file>debian/changelog</file> entry.
3251 The value of this field is usually extracted from the
3252 <file>debian/changelog</file> file - see
3253 <ref id="dpkgchangelog">).
3257 <sect1 id="f-Format">
3258 <heading><tt>Format</tt></heading>
3261 This field specifies a format revision for the file.
3262 The most current format described in the Policy Manual
3263 is version <strong>1.5</strong>. The syntax of the
3264 format value is the same as that of a package version
3265 number except that no epoch or Debian revision is allowed
3266 - see <ref id="f-Version">.
3270 <sect1 id="f-Urgency">
3271 <heading><tt>Urgency</tt></heading>
3274 This is a description of how important it is to upgrade to
3275 this version from previous ones. It consists of a single
3276 keyword taking one of the values <tt>low</tt>,
3277 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3278 <tt>critical</tt><footnote>
3279 Other urgency values are supported with configuration
3280 changes in the archive software but are not used in Debian.
3281 The urgency affects how quickly a package will be considered
3282 for inclusion into the <tt>testing</tt> distribution and
3283 gives an indication of the importance of any fixes included
3284 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3285 treated as synonymous.
3286 </footnote> (not case-sensitive) followed by an optional
3287 commentary (separated by a space) which is usually in
3288 parentheses. For example:
3291 Urgency: low (HIGH for users of diversions)
3297 The value of this field is usually extracted from the
3298 <file>debian/changelog</file> file - see
3299 <ref id="dpkgchangelog">.
3303 <sect1 id="f-Changes">
3304 <heading><tt>Changes</tt></heading>
3307 This field contains the human-readable changes data, describing
3308 the differences between the last version and the current one.
3312 The first line of the field value (the part on the same line
3313 as <tt>Changes:</tt>) is always empty. The content of the
3314 field is expressed as continuation lines, with each line
3315 indented by at least one space. Blank lines must be
3316 represented by a line consisting only of a space and a full
3321 The value of this field is usually extracted from the
3322 <file>debian/changelog</file> file - see
3323 <ref id="dpkgchangelog">).
3327 Each version's change information should be preceded by a
3328 "title" line giving at least the version, distribution(s)
3329 and urgency, in a human-readable way.
3333 If data from several versions is being returned the entry
3334 for the most recent version should be returned first, and
3335 entries should be separated by the representation of a
3336 blank line (the "title" line may also be followed by the
3337 representation of a blank line).
3341 <sect1 id="f-Binary">
3342 <heading><tt>Binary</tt></heading>
3345 This field is a list of binary packages. Its syntax and
3346 meaning varies depending on the control file in which it
3351 When it appears in the <file>.dsc</file> file, it lists binary
3352 packages which a source package can produce, separated by
3354 A space after each comma is conventional.
3355 </footnote>. It may span multiple lines. The source package
3356 does not necessarily produce all of these binary packages for
3357 every architecture. The source control file doesn't contain
3358 details of which architectures are appropriate for which of
3359 the binary packages.
3363 When it appears in a <file>.changes</file> file, it lists the
3364 names of the binary packages being uploaded, separated by
3365 whitespace (not commas). It may span multiple lines.
3369 <sect1 id="f-Installed-Size">
3370 <heading><tt>Installed-Size</tt></heading>
3373 This field appears in the control files of binary packages,
3374 and in the <file>Packages</file> files. It gives an estimate
3375 of the total amount of disk space required to install the
3376 named package. Actual installed size may vary based on block
3377 size, file system properties, or actions taken by package
3382 The disk space is given as the integer value of the estimated
3383 installed size in bytes, divided by 1024 and rounded up.
3387 <sect1 id="f-Files">
3388 <heading><tt>Files</tt></heading>
3391 This field contains a list of files with information about
3392 each one. The exact information and syntax varies with
3397 In all cases, Files is a multiline field. The first line of
3398 the field value (the part on the same line as <tt>Files:</tt>)
3399 is always empty. The content of the field is expressed as
3400 continuation lines, one line per file. Each line must be
3401 indented by one space and contain a number of sub-fields,
3402 separated by spaces, as described below.
3406 In the <file>.dsc</file> file, each line contains the MD5
3407 checksum, size and filename of the tar file and (if
3408 applicable) diff file which make up the remainder of the
3409 source package<footnote>
3410 That is, the parts which are not the <tt>.dsc</tt>.
3411 </footnote>. For example:
3414 c6f698f19f2a2aa07dbb9bbda90a2754 571925 example_1.2.orig.tar.gz
3415 938512f08422f3509ff36f125f5873ba 6220 example_1.2-1.diff.gz
3417 The exact forms of the filenames are described
3418 in <ref id="pkg-sourcearchives">.
3422 In the <file>.changes</file> file this contains one line per
3423 file being uploaded. Each line contains the MD5 checksum,
3424 size, section and priority and the filename. For example:
3427 4c31ab7bfc40d3cf49d7811987390357 1428 text extra example_1.2-1.dsc
3428 c6f698f19f2a2aa07dbb9bbda90a2754 571925 text extra example_1.2.orig.tar.gz
3429 938512f08422f3509ff36f125f5873ba 6220 text extra example_1.2-1.diff.gz
3430 7c98fe853b3bbb47a00e5cd129b6cb56 703542 text extra example_1.2-1_i386.deb
3432 The <qref id="f-Section">section</qref>
3433 and <qref id="f-Priority">priority</qref> are the values of
3434 the corresponding fields in the main source control file. If
3435 no section or priority is specified then <tt>-</tt> should be
3436 used, though section and priority values must be specified for
3437 new packages to be installed properly.
3441 The special value <tt>byhand</tt> for the section in a
3442 <tt>.changes</tt> file indicates that the file in question
3443 is not an ordinary package file and must by installed by
3444 hand by the distribution maintainers. If the section is
3445 <tt>byhand</tt> the priority should be <tt>-</tt>.
3449 If a new Debian revision of a package is being shipped and
3450 no new original source archive is being distributed the
3451 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3452 entry for the original source archive
3453 <file><var>package</var>_<var>upstream-version</var>.orig.tar.gz</file>,
3454 but the <file>.changes</file> file should leave it out. In
3455 this case the original source archive on the distribution
3456 site must match exactly, byte-for-byte, the original
3457 source archive which was used to generate the
3458 <file>.dsc</file> file and diff which are being uploaded.</p>
3461 <sect1 id="f-Closes">
3462 <heading><tt>Closes</tt></heading>
3465 A space-separated list of bug report numbers that the upload
3466 governed by the .changes file closes.
3470 <sect1 id="f-Homepage">
3471 <heading><tt>Homepage</tt></heading>
3474 The URL of the web site for this package, preferably (when
3475 applicable) the site from which the original source can be
3476 obtained and any additional upstream documentation or
3477 information may be found. The content of this field is a
3478 simple URL without any surrounding characters such as
3483 <sect1 id="f-Checksums">
3484 <heading><tt>Checksums-Sha1</tt>
3485 and <tt>Checksums-Sha256</tt></heading>
3488 These fields contain a list of files with a checksum and size
3489 for each one. Both <tt>Checksums-Sha1</tt>
3490 and <tt>Checksums-Sha256</tt> have the same syntax and differ
3491 only in the checksum algorithm used: SHA-1
3492 for <tt>Checksums-Sha1</tt> and SHA-256
3493 for <tt>Checksums-Sha256</tt>.
3497 <tt>Checksums-Sha1</tt> and <tt>Checksums-Sha256</tt> are
3498 multiline fields. The first line of the field value (the part
3499 on the same line as <tt>Checksums-Sha1:</tt>
3500 or <tt>Checksums-Sha256:</tt>) is always empty. The content
3501 of the field is expressed as continuation lines, one line per
3502 file. Each line consists of the checksum, a space, the file
3503 size, a space, and the file name. For example (from
3504 a <file>.changes</file> file):
3507 1f418afaa01464e63cc1ee8a66a05f0848bd155c 1276 example_1.0-1.dsc
3508 a0ed1456fad61116f868b1855530dbe948e20f06 171602 example_1.0.orig.tar.gz
3509 5e86ecf0671e113b63388dac81dd8d00e00ef298 6137 example_1.0-1.debian.tar.gz
3510 71a0ff7da0faaf608481195f9cf30974b142c183 548402 example_1.0-1_i386.deb
3512 ac9d57254f7e835bed299926fd51bf6f534597cc3fcc52db01c4bffedae81272 1276 example_1.0-1.dsc
3513 0d123be7f51e61c4bf15e5c492b484054be7e90f3081608a5517007bfb1fd128 171602 example_1.0.orig.tar.gz
3514 f54ae966a5f580571ae7d9ef5e1df0bd42d63e27cb505b27957351a495bc6288 6137 example_1.0-1.debian.tar.gz
3515 3bec05c03974fdecd11d020fc2e8250de8404867a8a2ce865160c250eb723664 548402 example_1.0-1_i386.deb
3520 In the <file>.dsc</file> file, these fields should list all
3521 files that make up the source package. In
3522 the <file>.changes</file> file, these fields should list all
3523 files being uploaded. The list of files in these fields
3524 must match the list of files in the <tt>Files</tt> field.
3531 <heading>User-defined fields</heading>
3534 Additional user-defined fields may be added to the
3535 source package control file. Such fields will be
3536 ignored, and not copied to (for example) binary or
3537 source package control files or upload control files.
3541 If you wish to add additional unsupported fields to
3542 these output files you should use the mechanism
3547 Fields in the main source control information file with
3548 names starting <tt>X</tt>, followed by one or more of
3549 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3550 be copied to the output files. Only the part of the
3551 field name after the hyphen will be used in the output
3552 file. Where the letter <tt>B</tt> is used the field
3553 will appear in binary package control files, where the
3554 letter <tt>S</tt> is used in source package control
3555 files and where <tt>C</tt> is used in upload control
3556 (<tt>.changes</tt>) files.
3560 For example, if the main source information control file
3563 XBS-Comment: I stand between the candle and the star.
3565 then the binary and source package control files will contain the
3568 Comment: I stand between the candle and the star.
3577 <chapt id="maintainerscripts">
3578 <heading>Package maintainer scripts and installation procedure</heading>
3581 <heading>Introduction to package maintainer scripts</heading>
3584 It is possible to supply scripts as part of a package which
3585 the package management system will run for you when your
3586 package is installed, upgraded or removed.
3590 These scripts are the files <prgn>preinst</prgn>,
3591 <prgn>postinst</prgn>, <prgn>prerm</prgn> and
3592 <prgn>postrm</prgn> in the control area of the package.
3593 They must be proper executable files; if they are scripts
3594 (which is recommended), they must start with the usual
3595 <tt>#!</tt> convention. They should be readable and
3596 executable by anyone, and must not be world-writable.
3600 The package management system looks at the exit status from
3601 these scripts. It is important that they exit with a
3602 non-zero status if there is an error, so that the package
3603 management system can stop its processing. For shell
3604 scripts this means that you <em>almost always</em> need to
3605 use <tt>set -e</tt> (this is usually true when writing shell
3606 scripts, in fact). It is also important, of course, that
3607 they exit with a zero status if everything went well.
3611 Additionally, packages interacting with users using
3612 <tt>debconf</tt> in the <prgn>postinst</prgn> script should
3613 install a <prgn>config</prgn> script in the control area,
3614 see <ref id="maintscriptprompt"> for details.
3618 When a package is upgraded a combination of the scripts from
3619 the old and new packages is called during the upgrade
3620 procedure. If your scripts are going to be at all
3621 complicated you need to be aware of this, and may need to
3622 check the arguments to your scripts.
3626 Broadly speaking the <prgn>preinst</prgn> is called before
3627 (a particular version of) a package is installed, and the
3628 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3629 before (a version of) a package is removed and the
3630 <prgn>postrm</prgn> afterwards.
3634 Programs called from maintainer scripts should not normally
3635 have a path prepended to them. Before installation is
3636 started, the package management system checks to see if the
3637 programs <prgn>ldconfig</prgn>,
3638 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3639 and <prgn>update-rc.d</prgn> can be found via the
3640 <tt>PATH</tt> environment variable. Those programs, and any
3641 other program that one would expect to be in the
3642 <tt>PATH</tt>, should thus be invoked without an absolute
3643 pathname. Maintainer scripts should also not reset the
3644 <tt>PATH</tt>, though they might choose to modify it by
3645 prepending or appending package-specific directories. These
3646 considerations really apply to all shell scripts.</p>
3649 <sect id="idempotency">
3650 <heading>Maintainer scripts idempotency</heading>
3653 It is necessary for the error recovery procedures that the
3654 scripts be idempotent. This means that if it is run
3655 successfully, and then it is called again, it doesn't bomb
3656 out or cause any harm, but just ensures that everything is
3657 the way it ought to be. If the first call failed, or
3658 aborted half way through for some reason, the second call
3659 should merely do the things that were left undone the first
3660 time, if any, and exit with a success status if everything
3662 This is so that if an error occurs, the user interrupts
3663 <prgn>dpkg</prgn> or some other unforeseen circumstance
3664 happens you don't leave the user with a badly-broken
3665 package when <prgn>dpkg</prgn> attempts to repeat the
3671 <sect id="controllingterminal">
3672 <heading>Controlling terminal for maintainer scripts</heading>
3675 Maintainer scripts are not guaranteed to run with a controlling
3676 terminal and may not be able to interact with the user. They
3677 must be able to fall back to noninteractive behavior if no
3678 controlling terminal is available. Maintainer scripts that
3679 prompt via a program conforming to the Debian Configuration
3680 Management Specification (see <ref id="maintscriptprompt">) may
3681 assume that program will handle falling back to noninteractive
3686 For high-priority prompts without a reasonable default answer,
3687 maintainer scripts may abort if there is no controlling
3688 terminal. However, this situation should be avoided if at all
3689 possible, since it prevents automated or unattended installs.
3690 In most cases, users will consider this to be a bug in the
3695 <sect id="exitstatus">
3696 <heading>Exit status</heading>
3699 Each script must return a zero exit status for
3700 success, or a nonzero one for failure, since the package
3701 management system looks for the exit status of these scripts
3702 and determines what action to take next based on that datum.
3706 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3711 <list compact="compact">
3713 <var>new-preinst</var> <tt>install</tt>
3716 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3719 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3722 <var>old-preinst</var> <tt>abort-upgrade</tt>
3723 <var>new-version</var>
3728 <list compact="compact">
3730 <var>postinst</var> <tt>configure</tt>
3731 <var>most-recently-configured-version</var>
3734 <var>old-postinst</var> <tt>abort-upgrade</tt>
3735 <var>new-version</var>
3738 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3739 <tt>in-favour</tt> <var>package</var>
3740 <var>new-version</var>
3743 <var>postinst</var> <tt>abort-remove</tt>
3746 <var>deconfigured's-postinst</var>
3747 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3748 <var>failed-install-package</var> <var>version</var>
3749 [<tt>removing</tt> <var>conflicting-package</var>
3755 <list compact="compact">
3757 <var>prerm</var> <tt>remove</tt>
3760 <var>old-prerm</var> <tt>upgrade</tt>
3761 <var>new-version</var>
3764 <var>new-prerm</var> <tt>failed-upgrade</tt>
3765 <var>old-version</var>
3768 <var>conflictor's-prerm</var> <tt>remove</tt>
3769 <tt>in-favour</tt> <var>package</var>
3770 <var>new-version</var>
3773 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3774 <tt>in-favour</tt> <var>package-being-installed</var>
3775 <var>version</var> [<tt>removing</tt>
3776 <var>conflicting-package</var>
3782 <list compact="compact">
3784 <var>postrm</var> <tt>remove</tt>
3787 <var>postrm</var> <tt>purge</tt>
3790 <var>old-postrm</var> <tt>upgrade</tt>
3791 <var>new-version</var>
3794 <var>new-postrm</var> <tt>failed-upgrade</tt>
3795 <var>old-version</var>
3798 <var>new-postrm</var> <tt>abort-install</tt>
3801 <var>new-postrm</var> <tt>abort-install</tt>
3802 <var>old-version</var>
3805 <var>new-postrm</var> <tt>abort-upgrade</tt>
3806 <var>old-version</var>
3809 <var>disappearer's-postrm</var> <tt>disappear</tt>
3810 <var>overwriter</var>
3811 <var>overwriter-version</var>
3817 <sect id="unpackphase">
3818 <heading>Details of unpack phase of installation or upgrade</heading>
3821 The procedure on installation/upgrade/overwrite/disappear
3822 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3823 stage of <tt>dpkg --install</tt>) is as follows. In each
3824 case, if a major error occurs (unless listed below) the
3825 actions are, in general, run backwards - this means that the
3826 maintainer scripts are run with different arguments in
3827 reverse order. These are the "error unwind" calls listed
3834 If a version of the package is already installed, call
3835 <example compact="compact">
3836 <var>old-prerm</var> upgrade <var>new-version</var>
3840 If the script runs but exits with a non-zero
3841 exit status, <prgn>dpkg</prgn> will attempt:
3842 <example compact="compact">
3843 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3845 If this works, the upgrade continues. If this
3846 does not work, the error unwind:
3847 <example compact="compact">
3848 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3850 If this works, then the old-version is
3851 "Installed", if not, the old version is in a
3852 "Half-Configured" state.
3858 If a "conflicting" package is being removed at the same time,
3859 or if any package will be broken (due to <tt>Breaks</tt>):
3862 If <tt>--auto-deconfigure</tt> is
3863 specified, call, for each package to be deconfigured
3864 due to <tt>Breaks</tt>:
3865 <example compact="compact">
3866 <var>deconfigured's-prerm</var> deconfigure \
3867 in-favour <var>package-being-installed</var> <var>version</var>
3870 <example compact="compact">
3871 <var>deconfigured's-postinst</var> abort-deconfigure \
3872 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3874 The deconfigured packages are marked as
3875 requiring configuration, so that if
3876 <tt>--install</tt> is used they will be
3877 configured again if possible.
3880 If any packages depended on a conflicting
3881 package being removed and <tt>--auto-deconfigure</tt> is
3882 specified, call, for each such package:
3883 <example compact="compact">
3884 <var>deconfigured's-prerm</var> deconfigure \
3885 in-favour <var>package-being-installed</var> <var>version</var> \
3886 removing <var>conflicting-package</var> <var>version</var>
3889 <example compact="compact">
3890 <var>deconfigured's-postinst</var> abort-deconfigure \
3891 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3892 removing <var>conflicting-package</var> <var>version</var>
3894 The deconfigured packages are marked as
3895 requiring configuration, so that if
3896 <tt>--install</tt> is used they will be
3897 configured again if possible.
3900 To prepare for removal of each conflicting package, call:
3901 <example compact="compact">
3902 <var>conflictor's-prerm</var> remove \
3903 in-favour <var>package</var> <var>new-version</var>
3906 <example compact="compact">
3907 <var>conflictor's-postinst</var> abort-remove \
3908 in-favour <var>package</var> <var>new-version</var>
3917 If the package is being upgraded, call:
3918 <example compact="compact">
3919 <var>new-preinst</var> upgrade <var>old-version</var>
3921 If this fails, we call:
3923 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3930 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3932 is called. If this works, then the old version
3933 is in an "Installed" state, or else it is left
3934 in an "Unpacked" state.
3939 If it fails, then the old version is left
3940 in an "Half-Installed" state.
3947 Otherwise, if the package had some configuration
3948 files from a previous version installed (i.e., it
3949 is in the "configuration files only" state):
3950 <example compact="compact">
3951 <var>new-preinst</var> install <var>old-version</var>
3955 <var>new-postrm</var> abort-install <var>old-version</var>
3957 If this fails, the package is left in a
3958 "Half-Installed" state, which requires a
3959 reinstall. If it works, the packages is left in
3960 a "Config-Files" state.
3963 Otherwise (i.e., the package was completely purged):
3964 <example compact="compact">
3965 <var>new-preinst</var> install
3968 <example compact="compact">
3969 <var>new-postrm</var> abort-install
3971 If the error-unwind fails, the package is in a
3972 "Half-Installed" phase, and requires a
3973 reinstall. If the error unwind works, the
3974 package is in a not installed state.
3981 The new package's files are unpacked, overwriting any
3982 that may be on the system already, for example any
3983 from the old version of the same package or from
3984 another package. Backups of the old files are kept
3985 temporarily, and if anything goes wrong the package
3986 management system will attempt to put them back as
3987 part of the error unwind.
3991 It is an error for a package to contain files which
3992 are on the system in another package, unless
3993 <tt>Replaces</tt> is used (see <ref id="replaces">).
3995 The following paragraph is not currently the case:
3996 Currently the <tt>- - force-overwrite</tt> flag is
3997 enabled, downgrading it to a warning, but this may not
4003 It is a more serious error for a package to contain a
4004 plain file or other kind of non-directory where another
4005 package has a directory (again, unless
4006 <tt>Replaces</tt> is used). This error can be
4007 overridden if desired using
4008 <tt>--force-overwrite-dir</tt>, but this is not
4013 Packages which overwrite each other's files produce
4014 behavior which, though deterministic, is hard for the
4015 system administrator to understand. It can easily
4016 lead to "missing" programs if, for example, a package
4017 is installed which overwrites a file from another
4018 package, and is then removed again.<footnote>
4019 Part of the problem is due to what is arguably a
4020 bug in <prgn>dpkg</prgn>.
4025 A directory will never be replaced by a symbolic link
4026 to a directory or vice versa; instead, the existing
4027 state (symlink or not) will be left alone and
4028 <prgn>dpkg</prgn> will follow the symlink if there is
4037 If the package is being upgraded, call
4038 <example compact="compact">
4039 <var>old-postrm</var> upgrade <var>new-version</var>
4043 If this fails, <prgn>dpkg</prgn> will attempt:
4044 <example compact="compact">
4045 <var>new-postrm</var> failed-upgrade <var>old-version</var>
4047 If this works, installation continues. If not,
4049 <example compact="compact">
4050 <var>old-preinst</var> abort-upgrade <var>new-version</var>
4052 If this fails, the old version is left in a
4053 "Half-Installed" state. If it works, dpkg now
4055 <example compact="compact">
4056 <var>new-postrm</var> abort-upgrade <var>old-version</var>
4058 If this fails, the old version is left in a
4059 "Half-Installed" state. If it works, dpkg now
4061 <example compact="compact">
4062 <var>old-postinst</var> abort-upgrade <var>new-version</var>
4064 If this fails, the old version is in an
4071 This is the point of no return - if
4072 <prgn>dpkg</prgn> gets this far, it won't back off
4073 past this point if an error occurs. This will
4074 leave the package in a fairly bad state, which
4075 will require a successful re-installation to clear
4076 up, but it's when <prgn>dpkg</prgn> starts doing
4077 things that are irreversible.
4082 Any files which were in the old version of the package
4083 but not in the new are removed.
4087 The new file list replaces the old.
4091 The new maintainer scripts replace the old.
4095 Any packages all of whose files have been overwritten
4096 during the installation, and which aren't required for
4097 dependencies, are considered to have been removed.
4098 For each such package
4101 <prgn>dpkg</prgn> calls:
4102 <example compact="compact">
4103 <var>disappearer's-postrm</var> disappear \
4104 <var>overwriter</var> <var>overwriter-version</var>
4108 The package's maintainer scripts are removed.
4111 It is noted in the status database as being in a
4112 sane state, namely not installed (any conffiles
4113 it may have are ignored, rather than being
4114 removed by <prgn>dpkg</prgn>). Note that
4115 disappearing packages do not have their prerm
4116 called, because <prgn>dpkg</prgn> doesn't know
4117 in advance that the package is going to
4124 Any files in the package we're unpacking that are also
4125 listed in the file lists of other packages are removed
4126 from those lists. (This will lobotomize the file list
4127 of the "conflicting" package if there is one.)
4131 The backup files made during installation, above, are
4137 The new package's status is now sane, and recorded as
4142 Here is another point of no return - if the
4143 conflicting package's removal fails we do not unwind
4144 the rest of the installation; the conflicting package
4145 is left in a half-removed limbo.
4150 If there was a conflicting package we go and do the
4151 removal actions (described below), starting with the
4152 removal of the conflicting package's files (any that
4153 are also in the package being installed have already
4154 been removed from the conflicting package's file list,
4155 and so do not get removed now).
4161 <sect id="configdetails"><heading>Details of configuration</heading>
4164 When we configure a package (this happens with <tt>dpkg
4165 --install</tt> and <tt>dpkg --configure</tt>), we first
4166 update any <tt>conffile</tt>s and then call:
4167 <example compact="compact">
4168 <var>postinst</var> configure <var>most-recently-configured-version</var>
4173 No attempt is made to unwind after errors during
4174 configuration. If the configuration fails, the package is in
4175 a "Failed Config" state, and an error message is generated.
4179 If there is no most recently configured version
4180 <prgn>dpkg</prgn> will pass a null argument.
4183 Historical note: Truly ancient (pre-1997) versions of
4184 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4185 (including the angle brackets) in this case. Even older
4186 ones did not pass a second argument at all, under any
4187 circumstance. Note that upgrades using such an old dpkg
4188 version are unlikely to work for other reasons, even if
4189 this old argument behavior is handled by your postinst script.
4195 <sect id="removedetails"><heading>Details of removal and/or
4196 configuration purging</heading>
4202 <example compact="compact">
4203 <var>prerm</var> remove
4207 If prerm fails during replacement due to conflict
4209 <var>conflictor's-postinst</var> abort-remove \
4210 in-favour <var>package</var> <var>new-version</var>
4214 <var>postinst</var> abort-remove
4218 If this fails, the package is in a "Half-Configured"
4219 state, or else it remains "Installed".
4223 The package's files are removed (except <tt>conffile</tt>s).
4226 <example compact="compact">
4227 <var>postrm</var> remove
4231 If it fails, there's no error unwind, and the package is in
4232 an "Half-Installed" state.
4237 All the maintainer scripts except the <prgn>postrm</prgn>
4242 If we aren't purging the package we stop here. Note
4243 that packages which have no <prgn>postrm</prgn> and no
4244 <tt>conffile</tt>s are automatically purged when
4245 removed, as there is no difference except for the
4246 <prgn>dpkg</prgn> status.
4250 The <tt>conffile</tt>s and any backup files
4251 (<tt>~</tt>-files, <tt>#*#</tt> files,
4252 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4257 <example compact="compact">
4258 <var>postrm</var> purge
4262 If this fails, the package remains in a "Config-Files"
4267 The package's file list is removed.
4276 <chapt id="relationships">
4277 <heading>Declaring relationships between packages</heading>
4279 <sect id="depsyntax">
4280 <heading>Syntax of relationship fields</heading>
4283 These fields all have a uniform syntax. They are a list of
4284 package names separated by commas.
4288 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4289 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4290 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4291 control file fields of the package, which declare
4292 dependencies on other packages, the package names listed may
4293 also include lists of alternative package names, separated
4294 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4295 if any one of the alternative packages is installed, that
4296 part of the dependency is considered to be satisfied.
4300 All of the fields except for <tt>Provides</tt> may restrict
4301 their applicability to particular versions of each named
4302 package. This is done in parentheses after each individual
4303 package name; the parentheses should contain a relation from
4304 the list below followed by a version number, in the format
4305 described in <ref id="f-Version">.
4309 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4310 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4311 strictly earlier, earlier or equal, exactly equal, later or
4312 equal and strictly later, respectively. The deprecated
4313 forms <tt><</tt> and <tt>></tt> were used to mean
4314 earlier/later or equal, rather than strictly earlier/later,
4315 so they should not appear in new packages (though
4316 <prgn>dpkg</prgn> still supports them).
4320 Whitespace may appear at any point in the version
4321 specification subject to the rules in <ref
4322 id="controlsyntax">, and must appear where it's necessary to
4323 disambiguate; it is not otherwise significant. All of the
4324 relationship fields may span multiple lines. For
4325 consistency and in case of future changes to
4326 <prgn>dpkg</prgn> it is recommended that a single space be
4327 used after a version relationship and before a version
4328 number; it is also conventional to put a single space after
4329 each comma, on either side of each vertical bar, and before
4330 each open parenthesis. When wrapping a relationship field, it
4331 is conventional to do so after a comma and before the space
4332 following that comma.
4336 For example, a list of dependencies might appear as:
4337 <example compact="compact">
4340 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4345 All fields that specify build-time relationships
4346 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4347 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
4348 may be restricted to a certain set of architectures. This
4349 is indicated in brackets after each individual package name and
4350 the optional version specification. The brackets enclose a
4351 list of Debian architecture names separated by whitespace.
4352 Exclamation marks may be prepended to each of the names.
4353 (It is not permitted for some names to be prepended with
4354 exclamation marks while others aren't.) If the current Debian
4355 host architecture is not in this list and there are no
4356 exclamation marks in the list, or it is in the list with a
4357 prepended exclamation mark, the package name and the
4358 associated version specification are ignored completely for
4359 the purposes of defining the relationships.
4364 <example compact="compact">
4366 Build-Depends-Indep: texinfo
4367 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4368 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4370 requires <tt>kernel-headers-2.2.10</tt> on all architectures
4371 other than hurd-i386 and requires <tt>hurd-dev</tt> and
4372 <tt>gnumach-dev</tt> only on hurd-i386.
4376 If the architecture-restricted dependency is part of a set of
4377 alternatives using <tt>|</tt>, that alternative is ignored
4378 completely on architectures that do not match the restriction.
4380 <example compact="compact">
4381 Build-Depends: foo [!i386] | bar [!amd64]
4383 is equivalent to <tt>bar</tt> on the i386 architecture, to
4384 <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
4385 bar</tt> on all other architectures.
4389 All fields that specify build-time relationships may also be
4390 restricted to a certain set of architectures using architecture
4391 wildcards. The syntax for declaring such restrictions is the
4392 same as declaring restrictions using a certain set of
4393 architectures without architecture wildcards. For example:
4394 <example compact="compact">
4395 Build-Depends: foo [linux-any], bar [any-i386], baz [!linux-any]
4397 is equivalent to <tt>foo</tt> on architectures using the Linux
4398 kernel and any cpu, <tt>bar</tt> on architectures using any
4399 kernel and an i386 cpu, and <tt>baz</tt> on any architecture
4400 using a kernel other than Linux.
4404 Note that the binary package relationship fields such as
4405 <tt>Depends</tt> appear in one of the binary package
4406 sections of the control file, whereas the build-time
4407 relationships such as <tt>Build-Depends</tt> appear in the
4408 source package section of the control file (which is the
4413 <sect id="binarydeps">
4414 <heading>Binary Dependencies - <tt>Depends</tt>,
4415 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4416 <tt>Pre-Depends</tt>
4420 Packages can declare in their control file that they have
4421 certain relationships to other packages - for example, that
4422 they may not be installed at the same time as certain other
4423 packages, and/or that they depend on the presence of others.
4427 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4428 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4429 <tt>Breaks</tt> and <tt>Conflicts</tt> control file fields.
4430 <tt>Breaks</tt> is described in <ref id="breaks">, and
4431 <tt>Conflicts</tt> is described in <ref id="conflicts">. The
4432 rest are described below.
4436 These seven fields are used to declare a dependency
4437 relationship by one package on another. Except for
4438 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4439 depending (binary) package's control file.
4440 (<tt>Enhances</tt> appears in the recommending package's
4441 control file, and <tt>Breaks</tt> appears in the version of
4442 depended-on package which causes the named package to
4447 A <tt>Depends</tt> field takes effect <em>only</em> when a
4448 package is to be configured. It does not prevent a package
4449 being on the system in an unconfigured state while its
4450 dependencies are unsatisfied, and it is possible to replace
4451 a package whose dependencies are satisfied and which is
4452 properly installed with a different version whose
4453 dependencies are not and cannot be satisfied; when this is
4454 done the depending package will be left unconfigured (since
4455 attempts to configure it will give errors) and will not
4456 function properly. If it is necessary, a
4457 <tt>Pre-Depends</tt> field can be used, which has a partial
4458 effect even when a package is being unpacked, as explained
4459 in detail below. (The other three dependency fields,
4460 <tt>Recommends</tt>, <tt>Suggests</tt> and
4461 <tt>Enhances</tt>, are only used by the various front-ends
4462 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4463 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4467 For this reason packages in an installation run are usually
4468 all unpacked first and all configured later; this gives
4469 later versions of packages with dependencies on later
4470 versions of other packages the opportunity to have their
4471 dependencies satisfied.
4475 In case of circular dependencies, since installation or
4476 removal order honoring the dependency order can't be
4477 established, dependency loops are broken at some point
4478 (based on rules below), and some packages may not be able to
4479 rely on their dependencies being present when being
4480 installed or removed, depending on which side of the break
4481 of the circular dependency loop they happen to be on. If one
4482 of the packages in the loop has no postinst script, then the
4483 cycle will be broken at that package, so as to ensure that
4484 all postinst scripts run with the dependencies properly
4485 configured if this is possible. Otherwise the breaking point
4490 The <tt>Depends</tt> field thus allows package maintainers
4491 to impose an order in which packages should be configured.
4495 The meaning of the five dependency fields is as follows:
4497 <tag><tt>Depends</tt></tag>
4500 This declares an absolute dependency. A package will
4501 not be configured unless all of the packages listed in
4502 its <tt>Depends</tt> field have been correctly
4507 The <tt>Depends</tt> field should be used if the
4508 depended-on package is required for the depending
4509 package to provide a significant amount of
4514 The <tt>Depends</tt> field should also be used if the
4515 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4516 <prgn>postrm</prgn> scripts require the package to be
4517 present in order to run. Note, however, that the
4518 <prgn>postrm</prgn> cannot rely on any non-essential
4519 packages to be present during the <tt>purge</tt>
4523 <tag><tt>Recommends</tt></tag>
4526 This declares a strong, but not absolute, dependency.
4530 The <tt>Recommends</tt> field should list packages
4531 that would be found together with this one in all but
4532 unusual installations.
4536 <tag><tt>Suggests</tt></tag>
4538 This is used to declare that one package may be more
4539 useful with one or more others. Using this field
4540 tells the packaging system and the user that the
4541 listed packages are related to this one and can
4542 perhaps enhance its usefulness, but that installing
4543 this one without them is perfectly reasonable.
4546 <tag><tt>Enhances</tt></tag>
4548 This field is similar to Suggests but works in the
4549 opposite direction. It is used to declare that a
4550 package can enhance the functionality of another
4554 <tag><tt>Pre-Depends</tt></tag>
4557 This field is like <tt>Depends</tt>, except that it
4558 also forces <prgn>dpkg</prgn> to complete installation
4559 of the packages named before even starting the
4560 installation of the package which declares the
4561 pre-dependency, as follows:
4565 When a package declaring a pre-dependency is about to
4566 be <em>unpacked</em> the pre-dependency can be
4567 satisfied if the depended-on package is either fully
4568 configured, <em>or even if</em> the depended-on
4569 package(s) are only unpacked or in the "Half-Configured"
4570 state, provided that they have been configured
4571 correctly at some point in the past (and not removed
4572 or partially removed since). In this case, both the
4573 previously-configured and currently unpacked or
4574 "Half-Configured" versions must satisfy any version
4575 clause in the <tt>Pre-Depends</tt> field.
4579 When the package declaring a pre-dependency is about
4580 to be <em>configured</em>, the pre-dependency will be
4581 treated as a normal <tt>Depends</tt>, that is, it will
4582 be considered satisfied only if the depended-on
4583 package has been correctly configured.
4587 <tt>Pre-Depends</tt> should be used sparingly,
4588 preferably only by packages whose premature upgrade or
4589 installation would hamper the ability of the system to
4590 continue with any upgrade that might be in progress.
4594 <tt>Pre-Depends</tt> are also required if the
4595 <prgn>preinst</prgn> script depends on the named
4596 package. It is best to avoid this situation if
4604 When selecting which level of dependency to use you should
4605 consider how important the depended-on package is to the
4606 functionality of the one declaring the dependency. Some
4607 packages are composed of components of varying degrees of
4608 importance. Such a package should list using
4609 <tt>Depends</tt> the package(s) which are required by the
4610 more important components. The other components'
4611 requirements may be mentioned as Suggestions or
4612 Recommendations, as appropriate to the components' relative
4618 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4621 When one binary package declares that it breaks another,
4622 <prgn>dpkg</prgn> will refuse to allow the package which
4623 declares <tt>Breaks</tt> be installed unless the broken
4624 package is deconfigured first, and it will refuse to
4625 allow the broken package to be reconfigured.
4629 A package will not be regarded as causing breakage merely
4630 because its configuration files are still installed; it must
4631 be at least "Half-Installed".
4635 A special exception is made for packages which declare that
4636 they break their own package name or a virtual package which
4637 they provide (see below): this does not count as a real
4642 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4643 version clause; such a <tt>Breaks</tt> is introduced in the
4644 version of an (implicit or explicit) dependency which
4645 violates an assumption or reveals a bug in earlier versions
4646 of the broken package. This use of <tt>Breaks</tt> will
4647 inform higher-level package management tools that broken
4648 package must be upgraded before the new one.
4652 If the breaking package also overwrites some files from the
4653 older package, it should use <tt>Replaces</tt> (not
4654 <tt>Conflicts</tt>) to ensure this goes smoothly.
4658 <sect id="conflicts">
4659 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4662 When one binary package declares a conflict with another
4663 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4664 refuse to allow them to be installed on the system at the
4669 If one package is to be installed, the other must be removed
4670 first - if the package being installed is marked as
4671 replacing (see <ref id="replaces">) the one on the system,
4672 or the one on the system is marked as deselected, or both
4673 packages are marked <tt>Essential</tt>, then
4674 <prgn>dpkg</prgn> will automatically remove the package
4675 which is causing the conflict, otherwise it will halt the
4676 installation of the new package with an error. This
4677 mechanism is specifically designed to produce an error when
4678 the installed package is <tt>Essential</tt>, but the new
4683 A package will not cause a conflict merely because its
4684 configuration files are still installed; it must be at least
4689 A special exception is made for packages which declare a
4690 conflict with their own package name, or with a virtual
4691 package which they provide (see below): this does not
4692 prevent their installation, and allows a package to conflict
4693 with others providing a replacement for it. You use this
4694 feature when you want the package in question to be the only
4695 package providing some feature.
4699 A <tt>Conflicts</tt> entry should almost never have an
4700 "earlier than" version clause. This would prevent
4701 <prgn>dpkg</prgn> from upgrading or installing the package
4702 which declared such a conflict until the upgrade or removal
4703 of the conflicted-with package had been completed. Instead,
4704 <tt>Breaks</tt> may be used.
4708 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4712 As well as the names of actual ("concrete") packages, the
4713 package relationship fields <tt>Depends</tt>,
4714 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4715 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4716 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4717 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4718 may mention "virtual packages".
4722 A <em>virtual package</em> is one which appears in the
4723 <tt>Provides</tt> control file field of another package.
4724 The effect is as if the package(s) which provide a
4725 particular virtual package name had been listed by name
4726 everywhere the virtual package name appears. (See also <ref
4731 If there are both concrete and virtual packages of the same
4732 name, then the dependency may be satisfied (or the conflict
4733 caused) by either the concrete package with the name in
4734 question or any other concrete package which provides the
4735 virtual package with the name in question. This is so that,
4736 for example, supposing we have
4737 <example compact="compact">
4740 </example> and someone else releases an enhanced version of
4741 the <tt>bar</tt> package they can say:
4742 <example compact="compact">
4746 and the <tt>bar-plus</tt> package will now also satisfy the
4747 dependency for the <tt>foo</tt> package.
4751 If a relationship field has a version number attached
4752 then only real packages will be considered to see whether
4753 the relationship is satisfied (or the prohibition violated,
4754 for a conflict or breakage) - it is assumed that a real
4755 package which provides the virtual package is not of the
4756 "right" version. So, a <tt>Provides</tt> field may not
4757 contain version numbers, and the version number of the
4758 concrete package which provides a particular virtual package
4759 will not be looked at when considering a dependency on or
4760 conflict with the virtual package name.
4764 It is likely that the ability will be added in a future
4765 release of <prgn>dpkg</prgn> to specify a version number for
4766 each virtual package it provides. This feature is not yet
4767 present, however, and is expected to be used only
4772 If you want to specify which of a set of real packages
4773 should be the default to satisfy a particular dependency on
4774 a virtual package, you should list the real package as an
4775 alternative before the virtual one.
4780 <sect id="replaces"><heading>Overwriting files and replacing
4781 packages - <tt>Replaces</tt></heading>
4784 Packages can declare in their control file that they should
4785 overwrite files in certain other packages, or completely
4786 replace other packages. The <tt>Replaces</tt> control file
4787 field has these two distinct purposes.
4790 <sect1><heading>Overwriting files in other packages</heading>
4793 Firstly, as mentioned before, it is usually an error for a
4794 package to contain files which are on the system in
4799 However, if the overwriting package declares that it
4800 <tt>Replaces</tt> the one containing the file being
4801 overwritten, then <prgn>dpkg</prgn> will replace the file
4802 from the old package with that from the new. The file
4803 will no longer be listed as "owned" by the old package.
4807 For example, if a package <package>foo</package> is split
4808 into <package>foo</package> and <package>foo-data</package>
4809 starting at version 1.2-3, <package>foo-data</package> should
4811 <example compact="compact">
4812 Replaces: foo (<< 1.2-3)
4814 in its control file. The package <package>foo</package>
4815 doesn't need any special control fields in this example,
4816 although would generally depend on or
4817 recommend <package>foo-data</package>.
4821 If a package is completely replaced in this way, so that
4822 <prgn>dpkg</prgn> does not know of any files it still
4823 contains, it is considered to have "disappeared". It will
4824 be marked as not wanted on the system (selected for
4825 removal) and not installed. Any <tt>conffile</tt>s
4826 details noted for the package will be ignored, as they
4827 will have been taken over by the overwriting package. The
4828 package's <prgn>postrm</prgn> script will be run with a
4829 special argument to allow the package to do any final
4830 cleanup required. See <ref id="mscriptsinstact">.
4833 Replaces is a one way relationship -- you have to
4834 install the replacing package after the replaced
4841 For this usage of <tt>Replaces</tt>, virtual packages (see
4842 <ref id="virtual">) are not considered when looking at a
4843 <tt>Replaces</tt> field - the packages declared as being
4844 replaced must be mentioned by their real names.
4848 Furthermore, this usage of <tt>Replaces</tt> only takes
4849 effect when both packages are at least partially on the
4850 system at once, so that it can only happen if they do not
4851 conflict or if the conflict has been overridden.
4856 <sect1><heading>Replacing whole packages, forcing their
4860 Secondly, <tt>Replaces</tt> allows the packaging system to
4861 resolve which package should be removed when there is a
4862 conflict - see <ref id="conflicts">. This usage only
4863 takes effect when the two packages <em>do</em> conflict,
4864 so that the two usages of this field do not interfere with
4869 In this situation, the package declared as being replaced
4870 can be a virtual package, so for example, all mail
4871 transport agents (MTAs) would have the following fields in
4872 their control files:
4873 <example compact="compact">
4874 Provides: mail-transport-agent
4875 Conflicts: mail-transport-agent
4876 Replaces: mail-transport-agent
4878 ensuring that only one MTA can be installed at any one
4883 <sect id="sourcebinarydeps">
4884 <heading>Relationships between source and binary packages -
4885 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4886 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4890 Source packages that require certain binary packages to be
4891 installed or absent at the time of building the package
4892 can declare relationships to those binary packages.
4896 This is done using the <tt>Build-Depends</tt>,
4897 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4898 <tt>Build-Conflicts-Indep</tt> control file fields.
4902 Build-dependencies on "build-essential" binary packages can be
4903 omitted. Please see <ref id="pkg-relations"> for more information.
4907 The dependencies and conflicts they define must be satisfied
4908 (as defined earlier for binary packages) in order to invoke
4909 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4911 There is no Build-Depends-Arch; this role is essentially
4912 met with Build-Depends. Anyone building the
4913 <tt>build-indep</tt> and binary-indep<tt></tt> targets is
4914 assumed to be building the whole package, and therefore
4915 installation of all build dependencies is required.
4918 The autobuilders use <tt>dpkg-buildpackage -B</tt>, which
4919 calls <tt>build</tt>, not <tt>build-arch</tt> since it does
4920 not yet know how to check for its existence, and
4921 <tt>binary-arch</tt>. The purpose of the original split
4922 between <tt>Build-Depends</tt> and
4923 <tt>Build-Depends-Indep</tt> was so that the autobuilders
4924 wouldn't need to install extra packages needed only for the
4925 binary-indep targets. But without a build-arch/build-indep
4926 split, this didn't work, since most of the work is done in
4927 the build target, not in the binary target.
4931 <tag><tt>clean</tt>, <tt>build-arch</tt>, and
4932 <tt>binary-arch</tt></tag>
4934 Only the <tt>Build-Depends</tt> and <tt>Build-Conflicts</tt>
4935 fields must be satisfied when these targets are invoked.
4937 <tag><tt>build</tt>, <tt>build-indep</tt>, <tt>binary</tt>,
4938 and <tt>binary-indep</tt></tag>
4940 The <tt>Build-Depends</tt>, <tt>Build-Conflicts</tt>,
4941 <tt>Build-Depends-Indep</tt>, and
4942 <tt>Build-Conflicts-Indep</tt> fields must be satisfied when
4943 these targets are invoked.
4951 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4954 Packages containing shared libraries must be constructed with
4955 a little care to make sure that the shared library is always
4956 available. This is especially important for packages whose
4957 shared libraries are vitally important, such as the C library
4958 (currently <tt>libc6</tt>).
4962 Packages involving shared libraries should be split up into
4963 several binary packages. This section mostly deals with how
4964 this separation is to be accomplished; rules for files within
4965 the shared library packages are in <ref id="libraries"> instead.
4968 <sect id="sharedlibs-runtime">
4969 <heading>Run-time shared libraries</heading>
4972 The run-time shared library needs to be placed in a package
4973 whose name changes whenever the shared object version
4976 Since it is common place to install several versions of a
4977 package that just provides shared libraries, it is a
4978 good idea that the library package should not
4979 contain any extraneous non-versioned files, unless they
4980 happen to be in versioned directories.</p>
4982 The most common mechanism is to place it in a package
4984 <package><var>libraryname</var><var>soversion</var></package>,
4985 where <file><var>soversion</var></file> is the version number
4986 in the soname of the shared library<footnote>
4987 The soname is the shared object name: it's the thing
4988 that has to match exactly between building an executable
4989 and running it for the dynamic linker to be able run the
4990 program. For example, if the soname of the library is
4991 <file>libfoo.so.6</file>, the library package would be
4992 called <file>libfoo6</file>.
4994 Alternatively, if it would be confusing to directly append
4995 <var>soversion</var> to <var>libraryname</var> (e.g. because
4996 <var>libraryname</var> itself ends in a number), you may use
4997 <package><var>libraryname</var>-<var>soversion</var></package> and
4998 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
5003 If you have several shared libraries built from the same
5004 source tree you may lump them all together into a single
5005 shared library package, provided that you change all of
5006 their sonames at once (so that you don't get filename
5007 clashes if you try to install different versions of the
5008 combined shared libraries package).
5012 The package should install the shared libraries under
5013 their normal names. For example, the <package>libgdbm3</package>
5014 package should install <file>libgdbm.so.3.0.0</file> as
5015 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
5016 renamed or re-linked by any <prgn>prerm</prgn> or
5017 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
5018 of renaming things safely without affecting running programs,
5019 and attempts to interfere with this are likely to lead to
5024 Shared libraries should not be installed executable, since
5025 the dynamic linker does not require this and trying to
5026 execute a shared library usually results in a core dump.
5030 The run-time library package should include the symbolic link that
5031 <prgn>ldconfig</prgn> would create for the shared libraries.
5032 For example, the <package>libgdbm3</package> package should include
5033 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
5034 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
5035 linker (for example <prgn>ld.so</prgn> or
5036 <prgn>ld-linux.so.*</prgn>) can find the library between the
5037 time that <prgn>dpkg</prgn> installs it and the time that
5038 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
5040 The package management system requires the library to be
5041 placed before the symbolic link pointing to it in the
5042 <file>.deb</file> file. This is so that when
5043 <prgn>dpkg</prgn> comes to install the symlink
5044 (overwriting the previous symlink pointing at an older
5045 version of the library), the new shared library is already
5046 in place. In the past, this was achieved by creating the
5047 library in the temporary packaging directory before
5048 creating the symlink. Unfortunately, this was not always
5049 effective, since the building of the tar file in the
5050 <file>.deb</file> depended on the behavior of the underlying
5051 file system. Some file systems (such as reiserfs) reorder
5052 the files so that the order of creation is forgotten.
5053 Since version 1.7.0, <prgn>dpkg</prgn>
5054 reorders the files itself as necessary when building a
5055 package. Thus it is no longer important to concern
5056 oneself with the order of file creation.
5060 <sect1 id="ldconfig">
5061 <heading><tt>ldconfig</tt></heading>
5064 Any package installing shared libraries in one of the default
5065 library directories of the dynamic linker (which are currently
5066 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
5067 listed in <file>/etc/ld.so.conf</file><footnote>
5069 <list compact="compact">
5070 <item>/usr/local/lib</item>
5071 <item>/usr/lib/libc5-compat</item>
5072 <item>/lib/libc5-compat</item>
5075 must use <prgn>ldconfig</prgn> to update the shared library
5080 The package maintainer scripts must only call
5081 <prgn>ldconfig</prgn> under these circumstances:
5082 <list compact="compact">
5083 <item>When the <prgn>postinst</prgn> script is run with a
5084 first argument of <tt>configure</tt>, the script must call
5085 <prgn>ldconfig</prgn>, and may optionally invoke
5086 <prgn>ldconfig</prgn> at other times.
5088 <item>When the <prgn>postrm</prgn> script is run with a
5089 first argument of <tt>remove</tt>, the script should call
5090 <prgn>ldconfig</prgn>.
5095 During install or upgrade, the preinst is called before
5096 the new files are installed, so calling "ldconfig" is
5097 pointless. The preinst of an existing package can also be
5098 called if an upgrade fails. However, this happens during
5099 the critical time when a shared libs may exist on-disk
5100 under a temporary name. Thus, it is dangerous and
5101 forbidden by current policy to call "ldconfig" at this
5106 When a package is installed or upgraded, "postinst
5107 configure" runs after the new files are safely on-disk.
5108 Since it is perfectly safe to invoke ldconfig
5109 unconditionally in a postinst, it is OK for a package to
5110 simply put ldconfig in its postinst without checking the
5111 argument. The postinst can also be called to recover from
5112 a failed upgrade. This happens before any new files are
5113 unpacked, so there is no reason to call "ldconfig" at this
5118 For a package that is being removed, prerm is
5119 called with all the files intact, so calling ldconfig is
5120 useless. The other calls to "prerm" happen in the case of
5121 upgrade at a time when all the files of the old package
5122 are on-disk, so again calling "ldconfig" is pointless.
5126 postrm, on the other hand, is called with the "remove"
5127 argument just after the files are removed, so this is
5128 the proper time to call "ldconfig" to notify the system
5129 of the fact that the shared libraries from the package
5130 are removed. The postrm can be called at several other
5131 times. At the time of "postrm purge", "postrm
5132 abort-install", or "postrm abort-upgrade", calling
5133 "ldconfig" is useless because the shared lib files are
5134 not on-disk. However, when "postrm" is invoked with
5135 arguments "upgrade", "failed-upgrade", or "disappear", a
5136 shared lib may exist on-disk under a temporary filename.
5144 <sect id="sharedlibs-support-files">
5145 <heading>Shared library support files</heading>
5148 If your package contains files whose names do not change with
5149 each change in the library shared object version, you must not
5150 put them in the shared library package. Otherwise, several
5151 versions of the shared library cannot be installed at the same
5152 time without filename clashes, making upgrades and transitions
5153 unnecessarily difficult.
5157 It is recommended that supporting files and run-time support
5158 programs that do not need to be invoked manually by users, but
5159 are nevertheless required for the package to function, be placed
5160 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
5161 preferably under <file>/usr/lib/</file><var>package-name</var>.
5162 If the program or file is architecture independent, the
5163 recommendation is for it to be placed in a subdirectory of
5164 <file>/usr/share</file> instead, preferably under
5165 <file>/usr/share/</file><var>package-name</var>. Following the
5166 <var>package-name</var> naming convention ensures that the file
5167 names change when the shared object version changes.
5171 Run-time support programs that use the shared library but are
5172 not required for the library to function or files used by the
5173 shared library that can be used by any version of the shared
5174 library package should instead be put in a separate package.
5175 This package might typically be named
5176 <package><var>libraryname</var>-tools</package>; note the
5177 absence of the <var>soversion</var> in the package name.
5181 Files and support programs only useful when compiling software
5182 against the library should be included in the development
5183 package for the library.<footnote>
5184 For example, a <file><var>package-name</var>-config</file>
5185 script or <package>pkg-config</package> configuration files.
5190 <sect id="sharedlibs-static">
5191 <heading>Static libraries</heading>
5194 The static library (<file><var>libraryname.a</var></file>)
5195 is usually provided in addition to the shared version.
5196 It is placed into the development package (see below).
5200 In some cases, it is acceptable for a library to be
5201 available in static form only; these cases include:
5203 <item>libraries for languages whose shared library support
5204 is immature or unstable</item>
5205 <item>libraries whose interfaces are in flux or under
5206 development (commonly the case when the library's
5207 major version number is zero, or where the ABI breaks
5208 across patchlevels)</item>
5209 <item>libraries which are explicitly intended to be
5210 available only in static form by their upstream
5215 <sect id="sharedlibs-dev">
5216 <heading>Development files</heading>
5219 The development files associated to a shared library need to be
5220 placed in a package called
5221 <package><var>libraryname</var><var>soversion</var>-dev</package>,
5222 or if you prefer only to support one development version at a
5223 time, <package><var>libraryname</var>-dev</package>.
5227 In case several development versions of a library exist, you may
5228 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5229 <ref id="conflicts">) to ensure that the user only installs one
5230 development version at a time (as different development versions are
5231 likely to have the same header files in them, which would cause a
5232 filename clash if both were installed).
5236 The development package should contain a symlink for the associated
5237 shared library without a version number. For example, the
5238 <package>libgdbm-dev</package> package should include a symlink
5239 from <file>/usr/lib/libgdbm.so</file> to
5240 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5241 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5242 <file>libgdbm.so</file> when compiling dynamically.
5246 <sect id="sharedlibs-intradeps">
5247 <heading>Dependencies between the packages of the same library</heading>
5250 Typically the development version should have an exact
5251 version dependency on the runtime library, to make sure that
5252 compilation and linking happens correctly. The
5253 <tt>${binary:Version}</tt> substitution variable can be
5254 useful for this purpose.
5256 Previously, <tt>${Source-Version}</tt> was used, but its name
5257 was confusing and it has been deprecated since dpkg 1.13.19.
5262 <sect id="sharedlibs-shlibdeps">
5263 <heading>Dependencies between the library and other packages -
5264 the <tt>shlibs</tt> system</heading>
5267 If a package contains a binary or library which links to a
5268 shared library, we must ensure that when the package is
5269 installed on the system, all of the libraries needed are
5270 also installed. This requirement led to the creation of the
5271 <tt>shlibs</tt> system, which is very simple in its design:
5272 any package which <em>provides</em> a shared library also
5273 provides information on the package dependencies required to
5274 ensure the presence of this library, and any package which
5275 <em>uses</em> a shared library uses this information to
5276 determine the dependencies it requires. The files which
5277 contain the mapping from shared libraries to the necessary
5278 dependency information are called <file>shlibs</file> files.
5282 Thus, when a package is built which contains any shared
5283 libraries, it must provide a <file>shlibs</file> file for other
5284 packages to use, and when a package is built which contains
5285 any shared libraries or compiled binaries, it must run
5286 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5287 on these to determine the libraries used and hence the
5288 dependencies needed by this package.<footnote>
5290 In the past, the shared libraries linked to were
5291 determined by calling <prgn>ldd</prgn>, but now
5292 <prgn>objdump</prgn> is used to do this. The only
5293 change this makes to package building is that
5294 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
5295 libraries, whereas in the past this was unnecessary.
5296 The rest of this footnote explains the advantage that
5301 We say that a binary <tt>foo</tt> <em>directly</em> uses
5302 a library <tt>libbar</tt> if it is explicitly linked
5303 with that library (that is, it uses the flag
5304 <tt>-lbar</tt> during the linking stage). Other
5305 libraries that are needed by <tt>libbar</tt> are linked
5306 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5307 linker will load them automatically when it loads
5308 <tt>libbar</tt>. A package should depend on
5309 the libraries it directly uses, and the dependencies for
5310 those libraries should automatically pull in the other
5315 Unfortunately, the <prgn>ldd</prgn> program shows both
5316 the directly and indirectly used libraries, meaning that
5317 the dependencies determined included both direct and
5318 indirect dependencies. The use of <prgn>objdump</prgn>
5319 avoids this problem by determining only the directly
5324 A good example of where this helps is the following. We
5325 could update <tt>libimlib</tt> with a new version that
5326 supports a new graphics format called dgf (but retaining
5327 the same major version number). If we used the old
5328 <prgn>ldd</prgn> method, every package that uses
5329 <tt>libimlib</tt> would need to be recompiled so it
5330 would also depend on <tt>libdgf</tt> or it wouldn't run
5331 due to missing symbols. However with the new system,
5332 packages using <tt>libimlib</tt> can rely on
5333 <tt>libimlib</tt> itself having the dependency on
5334 <tt>libdgf</tt> and so they would not need rebuilding.
5340 In the following sections, we will first describe where the
5341 various <tt>shlibs</tt> files are to be found, then how to
5342 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5343 file format and how to create them if your package contains a
5348 <heading>The <tt>shlibs</tt> files present on the system</heading>
5351 There are several places where <tt>shlibs</tt> files are
5352 found. The following list gives them in the order in which
5354 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5355 (The first one which gives the required information is used.)
5361 <p><file>debian/shlibs.local</file></p>
5364 This lists overrides for this package. Its use is
5365 described below (see <ref id="shlibslocal">).
5370 <p><file>/etc/dpkg/shlibs.override</file></p>
5373 This lists global overrides. This list is normally
5374 empty. It is maintained by the local system
5380 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5383 When packages are being built, any
5384 <file>debian/shlibs</file> files are copied into the
5385 control file area of the temporary build directory and
5386 given the name <file>shlibs</file>. These files give
5387 details of any shared libraries included in the
5389 An example may help here. Let us say that the
5390 source package <tt>foo</tt> generates two binary
5391 packages, <tt>libfoo2</tt> and
5392 <tt>foo-runtime</tt>. When building the binary
5393 packages, the two packages are created in the
5394 directories <file>debian/libfoo2</file> and
5395 <file>debian/foo-runtime</file> respectively.
5396 (<file>debian/tmp</file> could be used instead of one
5397 of these.) Since <tt>libfoo2</tt> provides the
5398 <tt>libfoo</tt> shared library, it will require a
5399 <tt>shlibs</tt> file, which will be installed in
5400 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
5402 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
5403 when <prgn>dpkg-shlibdeps</prgn> is run on the
5405 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
5407 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5408 determine whether <tt>foo-prog</tt>'s library
5409 dependencies are satisfied by any of the libraries
5410 provided by <tt>libfoo2</tt>. For this reason,
5411 <prgn>dpkg-shlibdeps</prgn> must only be run once
5412 all of the individual binary packages'
5413 <tt>shlibs</tt> files have been installed into the
5420 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5423 These are the <file>shlibs</file> files corresponding to
5424 all of the packages installed on the system, and are
5425 maintained by the relevant package maintainers.
5430 <p><file>/etc/dpkg/shlibs.default</file></p>
5433 This file lists any shared libraries whose packages
5434 have failed to provide correct <file>shlibs</file> files.
5435 It was used when the <file>shlibs</file> setup was first
5436 introduced, but it is now normally empty. It is
5437 maintained by the <tt>dpkg</tt> maintainer.
5445 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5446 <file>shlibs</file> files</heading>
5450 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5451 into your <file>debian/rules</file> file. If your package
5452 contains only compiled binaries and libraries (but no scripts),
5453 you can use a command such as:
5454 <example compact="compact">
5455 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5456 debian/tmp/usr/lib/*
5458 Otherwise, you will need to explicitly list the compiled
5459 binaries and libraries.<footnote>
5460 If you are using <tt>debhelper</tt>, the
5461 <prgn>dh_shlibdeps</prgn> program will do this work for
5462 you. It will also correctly handle multi-binary
5468 This command puts the dependency information into the
5469 <file>debian/substvars</file> file, which is then used by
5470 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5471 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5472 field in the control file for this to work.
5476 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
5477 done. If it does complain you might need to create your own
5478 <file>debian/shlibs.local</file> file, as explained below (see
5479 <ref id="shlibslocal">).
5483 If you have multiple binary packages, you will need to call
5484 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5485 compiled libraries or binaries. In such a case, you will
5486 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5487 utilities to specify a different <file>substvars</file> file.
5491 If you are creating a udeb for use in the Debian Installer,
5492 you will need to specify that <prgn>dpkg-shlibdeps</prgn>
5493 should use the dependency line of type <tt>udeb</tt> by
5494 adding the <tt>-tudeb</tt> option<footnote>
5495 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5496 will automatically add this option if it knows it is
5498 </footnote>. If there is no dependency line of type <tt>udeb</tt>
5499 in the <file>shlibs</file> file, <prgn>dpkg-shlibdeps</prgn> will
5500 fall back to the regular dependency line.
5504 For more details on dpkg-shlibdeps, please see
5505 <ref id="pkg-dpkg-shlibdeps"> and
5506 <manref name="dpkg-shlibdeps" section="1">.
5511 <heading>The <file>shlibs</file> File Format</heading>
5514 Each <file>shlibs</file> file has the same format. Lines
5515 beginning with <tt>#</tt> are considered to be comments and
5516 are ignored. Each line is of the form:
5517 <example compact="compact">
5518 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5523 We will explain this by reference to the example of the
5524 <tt>zlib1g</tt> package, which (at the time of writing)
5525 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5529 <var>type</var> is an optional element that indicates the type
5530 of package for which the line is valid. The only type currently
5531 in use is <tt>udeb</tt>. The colon and space after the type are
5536 <var>library-name</var> is the name of the shared library,
5537 in this case <tt>libz</tt>. (This must match the name part
5538 of the soname, see below.)
5542 <var>soname-version</var> is the version part of the soname of
5543 the library. The soname is the thing that must exactly match
5544 for the library to be recognized by the dynamic linker, and is
5546 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5547 example, <tt>libz.so.1</tt>.<footnote>
5548 This can be determined using the command
5549 <example compact="compact">
5550 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5553 The version part is the part which comes after
5554 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
5558 <var>dependencies</var> has the same syntax as a dependency
5559 field in a binary package control file. It should give
5560 details of which packages are required to satisfy a binary
5561 built against the version of the library contained in the
5562 package. See <ref id="depsyntax"> for details.
5566 In our example, if the first version of the <tt>zlib1g</tt>
5567 package which contained a minor number of at least
5568 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5569 <tt>shlibs</tt> entry for this library could say:
5570 <example compact="compact">
5571 libz 1 zlib1g (>= 1:1.1.3)
5573 The version-specific dependency is to avoid warnings from
5574 the dynamic linker about using older shared libraries with
5579 As zlib1g also provides a udeb containing the shared library,
5580 there would also be a second line:
5581 <example compact="compact">
5582 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5588 <heading>Providing a <file>shlibs</file> file</heading>
5591 If your package provides a shared library, you need to create
5592 a <file>shlibs</file> file following the format described above.
5593 It is usual to call this file <file>debian/shlibs</file> (but if
5594 you have multiple binary packages, you might want to call it
5595 <file>debian/shlibs.<var>package</var></file> instead). Then
5596 let <file>debian/rules</file> install it in the control area:
5597 <example compact="compact">
5598 install -m644 debian/shlibs debian/tmp/DEBIAN
5600 or, in the case of a multi-binary package:
5601 <example compact="compact">
5602 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5604 An alternative way of doing this is to create the
5605 <file>shlibs</file> file in the control area directly from
5606 <file>debian/rules</file> without using a <file>debian/shlibs</file>
5607 file at all,<footnote>
5608 This is what <prgn>dh_makeshlibs</prgn> in the
5609 <tt>debhelper</tt> suite does. If your package also has a udeb
5610 that provides a shared library, <prgn>dh_makeshlibs</prgn> can
5611 automatically generate the <tt>udeb:</tt> lines if you specify
5612 the name of the udeb with the <tt>--add-udeb</tt> option.
5614 since the <file>debian/shlibs</file> file itself is ignored by
5615 <prgn>dpkg-shlibdeps</prgn>.
5619 As <prgn>dpkg-shlibdeps</prgn> reads the
5620 <file>DEBIAN/shlibs</file> files in all of the binary packages
5621 being built from this source package, all of the
5622 <file>DEBIAN/shlibs</file> files should be installed before
5623 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5628 <sect1 id="shlibslocal">
5629 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
5632 This file is intended only as a <em>temporary</em> fix if
5633 your binaries or libraries depend on a library whose package
5634 does not yet provide a correct <file>shlibs</file> file.
5638 We will assume that you are trying to package a binary
5639 <tt>foo</tt>. When you try running
5640 <prgn>dpkg-shlibdeps</prgn> you get the following error
5641 message (<tt>-O</tt> displays the dependency information on
5642 <tt>stdout</tt> instead of writing it to
5643 <tt>debian/substvars</tt>, and the lines have been wrapped
5644 for ease of reading):
5645 <example compact="compact">
5646 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
5647 dpkg-shlibdeps: warning: unable to find dependency
5648 information for shared library libbar (soname 1,
5649 path /usr/lib/libbar.so.1, dependency field Depends)
5650 shlibs:Depends=libc6 (>= 2.2.2-2)
5652 You can then run <prgn>ldd</prgn> on the binary to find the
5653 full location of the library concerned:
5654 <example compact="compact">
5656 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5657 libc.so.6 => /lib/libc.so.6 (0x40032000)
5658 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5660 So the <prgn>foo</prgn> binary depends on the
5661 <prgn>libbar</prgn> shared library, but no package seems to
5662 provide a <file>*.shlibs</file> file handling
5663 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5664 determine the package responsible:
5665 <example compact="compact">
5666 $ dpkg -S /usr/lib/libbar.so.1
5667 bar1: /usr/lib/libbar.so.1
5668 $ dpkg -s bar1 | grep Version
5671 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5672 is the one we are using. Now we can file a bug against the
5673 <tt>bar1</tt> package and create our own
5674 <file>debian/shlibs.local</file> to locally fix the problem.
5675 Including the following line into your
5676 <file>debian/shlibs.local</file> file:
5677 <example compact="compact">
5678 libbar 1 bar1 (>= 1.0-1)
5680 should allow the package build to work.
5684 As soon as the maintainer of <tt>bar1</tt> provides a
5685 correct <file>shlibs</file> file, you should remove this line
5686 from your <file>debian/shlibs.local</file> file. (You should
5687 probably also then have a versioned <tt>Build-Depends</tt>
5688 on <tt>bar1</tt> to help ensure that others do not have the
5689 same problem building your package.)
5698 <chapt id="opersys"><heading>The Operating System</heading>
5701 <heading>File system hierarchy</heading>
5705 <heading>File System Structure</heading>
5708 The location of all installed files and directories must
5709 comply with the Filesystem Hierarchy Standard (FHS),
5710 version 2.3, with the exceptions noted below, and except
5711 where doing so would violate other terms of Debian
5712 Policy. The following exceptions to the FHS apply:
5717 The optional rules related to user specific
5718 configuration files for applications are stored in
5719 the user's home directory are relaxed. It is
5720 recommended that such files start with the
5721 '<tt>.</tt>' character (a "dot file"), and if an
5722 application needs to create more than one dot file
5723 then the preferred placement is in a subdirectory
5724 with a name starting with a '.' character, (a "dot
5725 directory"). In this case it is recommended the
5726 configuration files not start with the '.'
5732 The requirement for amd64 to use <file>/lib64</file>
5733 for 64 bit binaries is removed.
5738 The requirement for object files, internal binaries, and
5739 libraries, including <file>libc.so.*</file>, to be located
5740 directly under <file>/lib{,32}</file> and
5741 <file>/usr/lib{,32}</file> is amended, permitting files
5742 to instead be installed to
5743 <file>/lib/<var>triplet</var></file> and
5744 <file>/usr/lib/<var>triplet</var></file>, where
5745 <tt><var>triplet</var></tt> is the value returned by
5746 <tt>dpkg-architecture -qDEB_HOST_GNU_TYPE</tt> for the
5747 architecture of the package. Packages may <em>not</em>
5748 install files to any <var>triplet</var> path other
5749 than the one matching the architecture of that package;
5750 for instance, an <tt>Architecture: amd64</tt> package
5751 containing 32-bit x86 libraries may not install these
5752 libraries to <file>/usr/lib/i486-linux-gnu</file>.
5754 This is necessary in order to reserve the directories for
5755 use in cross-installation of library packages from other
5756 architectures, as part of the planned deployment of
5761 Applications may also use a single subdirectory under
5762 <file>/usr/lib/<var>triplet</var></file>.
5765 The execution time linker/loader, ld*, must still be made
5766 available in the existing location under /lib or /lib64
5767 since this is part of the ELF ABI for the architecture.
5772 The requirement that
5773 <file>/usr/local/share/man</file> be "synonymous"
5774 with <file>/usr/local/man</file> is relaxed to a
5779 The requirement that windowmanagers with a single
5780 configuration file call it <file>system.*wmrc</file>
5781 is removed, as is the restriction that the window
5782 manager subdirectory be named identically to the
5783 window manager name itself.
5788 The requirement that boot manager configuration
5789 files live in <file>/etc</file>, or at least are
5790 symlinked there, is relaxed to a recommendation.
5795 The following directories in the root filesystem are
5796 additionally allowed: <file>/sys</file> and
5797 <file>/selinux</file>. <footnote>These directories
5798 are used as mount points to mount virtual filesystems
5799 to get access to kernel information.</footnote>
5806 The version of this document referred here can be
5807 found in the <tt>debian-policy</tt> package or on <url
5808 id="http://www.debian.org/doc/packaging-manuals/fhs/"
5809 name="FHS (Debian copy)"> alongside this manual (or, if
5810 you have the <package>debian-policy</package> installed,
5812 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5813 (local copy)">). The
5814 latest version, which may be a more recent version, may
5816 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5817 Specific questions about following the standard may be
5818 asked on the <tt>debian-devel</tt> mailing list, or
5819 referred to the FHS mailing list (see the
5820 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5826 <heading>Site-specific programs</heading>
5829 As mandated by the FHS, packages must not place any
5830 files in <file>/usr/local</file>, either by putting them in
5831 the file system archive to be unpacked by <prgn>dpkg</prgn>
5832 or by manipulating them in their maintainer scripts.
5836 However, the package may create empty directories below
5837 <file>/usr/local</file> so that the system administrator knows
5838 where to place site-specific files. These are not
5839 directories <em>in</em> <file>/usr/local</file>, but are
5840 children of directories in <file>/usr/local</file>. These
5841 directories (<file>/usr/local/*/dir/</file>)
5842 should be removed on package removal if they are
5847 Note that this applies only to
5848 directories <em>below</em> <file>/usr/local</file>,
5849 not <em>in</em> <file>/usr/local</file>. Packages must
5850 not create sub-directories in the
5851 directory <file>/usr/local</file> itself, except those
5852 listed in FHS, section 4.5. However, you may create
5853 directories below them as you wish. You must not remove
5854 any of the directories listed in 4.5, even if you created
5859 Since <file>/usr/local</file> can be mounted read-only from a
5860 remote server, these directories must be created and
5861 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5862 maintainer scripts and not be included in the
5863 <file>.deb</file> archive. These scripts must not fail if
5864 either of these operations fail.
5868 For example, the <tt>emacsen-common</tt> package could
5869 contain something like
5870 <example compact="compact">
5871 if [ ! -e /usr/local/share/emacs ]
5873 if mkdir /usr/local/share/emacs 2>/dev/null
5875 chown root:staff /usr/local/share/emacs
5876 chmod 2775 /usr/local/share/emacs
5880 in its <prgn>postinst</prgn> script, and
5881 <example compact="compact">
5882 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5883 rmdir /usr/local/share/emacs 2>/dev/null || true
5885 in the <prgn>prerm</prgn> script. (Note that this form is
5886 used to ensure that if the script is interrupted, the
5887 directory <file>/usr/local/share/emacs</file> will still be
5892 If you do create a directory in <file>/usr/local</file> for
5893 local additions to a package, you should ensure that
5894 settings in <file>/usr/local</file> take precedence over the
5895 equivalents in <file>/usr</file>.
5899 However, because <file>/usr/local</file> and its contents are
5900 for exclusive use of the local administrator, a package
5901 must not rely on the presence or absence of files or
5902 directories in <file>/usr/local</file> for normal operation.
5906 The <file>/usr/local</file> directory itself and all the
5907 subdirectories created by the package should (by default) have
5908 permissions 2775 (group-writable and set-group-id) and be
5909 owned by <tt>root:staff</tt>.
5914 <heading>The system-wide mail directory</heading>
5916 The system-wide mail directory
5917 is <file>/var/mail</file>. This directory is part of the
5918 base system and should not be owned by any particular mail
5919 agents. The use of the old
5920 location <file>/var/spool/mail</file> is deprecated, even
5921 though the spool may still be physically located there.
5927 <heading>Users and groups</heading>
5930 <heading>Introduction</heading>
5932 The Debian system can be configured to use either plain or
5937 Some user ids (UIDs) and group ids (GIDs) are reserved
5938 globally for use by certain packages. Because some
5939 packages need to include files which are owned by these
5940 users or groups, or need the ids compiled into binaries,
5941 these ids must be used on any Debian system only for the
5942 purpose for which they are allocated. This is a serious
5943 restriction, and we should avoid getting in the way of
5944 local administration policies. In particular, many sites
5945 allocate users and/or local system groups starting at 100.
5949 Apart from this we should have dynamically allocated ids,
5950 which should by default be arranged in some sensible
5951 order, but the behavior should be configurable.
5955 Packages other than <tt>base-passwd</tt> must not modify
5956 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5957 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5962 <heading>UID and GID classes</heading>
5964 The UID and GID numbers are divided into classes as
5970 Globally allocated by the Debian project, the same
5971 on every Debian system. These ids will appear in
5972 the <file>passwd</file> and <file>group</file> files of all
5973 Debian systems, new ids in this range being added
5974 automatically as the <tt>base-passwd</tt> package is
5979 Packages which need a single statically allocated
5980 uid or gid should use one of these; their
5981 maintainers should ask the <tt>base-passwd</tt>
5989 Dynamically allocated system users and groups.
5990 Packages which need a user or group, but can have
5991 this user or group allocated dynamically and
5992 differently on each system, should use <tt>adduser
5993 --system</tt> to create the group and/or user.
5994 <prgn>adduser</prgn> will check for the existence of
5995 the user or group, and if necessary choose an unused
5996 id based on the ranges specified in
5997 <file>adduser.conf</file>.
6001 <tag>1000-59999:</tag>
6004 Dynamically allocated user accounts. By default
6005 <prgn>adduser</prgn> will choose UIDs and GIDs for
6006 user accounts in this range, though
6007 <file>adduser.conf</file> may be used to modify this
6012 <tag>60000-64999:</tag>
6015 Globally allocated by the Debian project, but only
6016 created on demand. The ids are allocated centrally
6017 and statically, but the actual accounts are only
6018 created on users' systems on demand.
6022 These ids are for packages which are obscure or
6023 which require many statically-allocated ids. These
6024 packages should check for and create the accounts in
6025 <file>/etc/passwd</file> or <file>/etc/group</file> (using
6026 <prgn>adduser</prgn> if it has this facility) if
6027 necessary. Packages which are likely to require
6028 further allocations should have a "hole" left after
6029 them in the allocation, to give them room to
6034 <tag>65000-65533:</tag>
6042 User <tt>nobody</tt>. The corresponding gid refers
6043 to the group <tt>nogroup</tt>.
6050 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
6051 not</em> be used, because it is the error return
6060 <sect id="sysvinit">
6061 <heading>System run levels and <file>init.d</file> scripts</heading>
6063 <sect1 id="/etc/init.d">
6064 <heading>Introduction</heading>
6067 The <file>/etc/init.d</file> directory contains the scripts
6068 executed by <prgn>init</prgn> at boot time and when the
6069 init state (or "runlevel") is changed (see <manref
6070 name="init" section="8">).
6074 There are at least two different, yet functionally
6075 equivalent, ways of handling these scripts. For the sake
6076 of simplicity, this document describes only the symbolic
6077 link method. However, it must not be assumed by maintainer
6078 scripts that this method is being used, and any automated
6079 manipulation of the various runlevel behaviors by
6080 maintainer scripts must be performed using
6081 <prgn>update-rc.d</prgn> as described below and not by
6082 manually installing or removing symlinks. For information
6083 on the implementation details of the other method,
6084 implemented in the <tt>file-rc</tt> package, please refer
6085 to the documentation of that package.
6089 These scripts are referenced by symbolic links in the
6090 <file>/etc/rc<var>n</var>.d</file> directories. When changing
6091 runlevels, <prgn>init</prgn> looks in the directory
6092 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
6093 execute, where <tt><var>n</var></tt> is the runlevel that
6094 is being changed to, or <tt>S</tt> for the boot-up
6099 The names of the links all have the form
6100 <file>S<var>mm</var><var>script</var></file> or
6101 <file>K<var>mm</var><var>script</var></file> where
6102 <var>mm</var> is a two-digit number and <var>script</var>
6103 is the name of the script (this should be the same as the
6104 name of the actual script in <file>/etc/init.d</file>).
6108 When <prgn>init</prgn> changes runlevel first the targets
6109 of the links whose names start with a <tt>K</tt> are
6110 executed, each with the single argument <tt>stop</tt>,
6111 followed by the scripts prefixed with an <tt>S</tt>, each
6112 with the single argument <tt>start</tt>. (The links are
6113 those in the <file>/etc/rc<var>n</var>.d</file> directory
6114 corresponding to the new runlevel.) The <tt>K</tt> links
6115 are responsible for killing services and the <tt>S</tt>
6116 link for starting services upon entering the runlevel.
6120 For example, if we are changing from runlevel 2 to
6121 runlevel 3, init will first execute all of the <tt>K</tt>
6122 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
6123 all of the <tt>S</tt> prefixed scripts in that directory.
6124 The links starting with <tt>K</tt> will cause the
6125 referred-to file to be executed with an argument of
6126 <tt>stop</tt>, and the <tt>S</tt> links with an argument
6131 The two-digit number <var>mm</var> is used to determine
6132 the order in which to run the scripts: low-numbered links
6133 have their scripts run first. For example, the
6134 <tt>K20</tt> scripts will be executed before the
6135 <tt>K30</tt> scripts. This is used when a certain service
6136 must be started before another. For example, the name
6137 server <prgn>bind</prgn> might need to be started before
6138 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
6139 can set up its access lists. In this case, the script
6140 that starts <prgn>bind</prgn> would have a lower number
6141 than the script that starts <prgn>inn</prgn> so that it
6143 <example compact="compact">
6150 The two runlevels 0 (halt) and 6 (reboot) are slightly
6151 different. In these runlevels, the links with an
6152 <tt>S</tt> prefix are still called after those with a
6153 <tt>K</tt> prefix, but they too are called with the single
6154 argument <tt>stop</tt>.
6158 <sect1 id="writing-init">
6159 <heading>Writing the scripts</heading>
6162 Packages that include daemons for system services should
6163 place scripts in <file>/etc/init.d</file> to start or stop
6164 services at boot time or during a change of runlevel.
6165 These scripts should be named
6166 <file>/etc/init.d/<var>package</var></file>, and they should
6167 accept one argument, saying what to do:
6170 <tag><tt>start</tt></tag>
6171 <item>start the service,</item>
6173 <tag><tt>stop</tt></tag>
6174 <item>stop the service,</item>
6176 <tag><tt>restart</tt></tag>
6177 <item>stop and restart the service if it's already running,
6178 otherwise start the service</item>
6180 <tag><tt>reload</tt></tag>
6181 <item><p>cause the configuration of the service to be
6182 reloaded without actually stopping and restarting
6185 <tag><tt>force-reload</tt></tag>
6186 <item>cause the configuration to be reloaded if the
6187 service supports this, otherwise restart the
6191 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
6192 <tt>force-reload</tt> options should be supported by all
6193 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
6198 The <file>init.d</file> scripts must ensure that they will
6199 behave sensibly (i.e., returning success and not starting
6200 multiple copies of a service) if invoked with <tt>start</tt>
6201 when the service is already running, or with <tt>stop</tt>
6202 when it isn't, and that they don't kill unfortunately-named
6203 user processes. The best way to achieve this is usually to
6204 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
6209 Be careful of using <tt>set -e</tt> in <file>init.d</file>
6210 scripts. Writing correct <file>init.d</file> scripts requires
6211 accepting various error exit statuses when daemons are already
6212 running or already stopped without aborting
6213 the <file>init.d</file> script, and common <file>init.d</file>
6214 function libraries are not safe to call with <tt>set -e</tt>
6216 <tt>/lib/lsb/init-functions</tt>, which assists in writing
6217 LSB-compliant init scripts, may fail if <tt>set -e</tt> is
6218 in effect and echoing status messages to the console fails,
6220 </footnote>. For <tt>init.d</tt> scripts, it's often easier
6221 to not use <tt>set -e</tt> and instead check the result of
6222 each command separately.
6226 If a service reloads its configuration automatically (as
6227 in the case of <prgn>cron</prgn>, for example), the
6228 <tt>reload</tt> option of the <file>init.d</file> script
6229 should behave as if the configuration has been reloaded
6234 The <file>/etc/init.d</file> scripts must be treated as
6235 configuration files, either (if they are present in the
6236 package, that is, in the .deb file) by marking them as
6237 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
6238 by managing them correctly in the maintainer scripts (see
6239 <ref id="config-files">). This is important since we want
6240 to give the local system administrator the chance to adapt
6241 the scripts to the local system, e.g., to disable a
6242 service without de-installing the package, or to specify
6243 some special command line options when starting a service,
6244 while making sure their changes aren't lost during the next
6249 These scripts should not fail obscurely when the
6250 configuration files remain but the package has been
6251 removed, as configuration files remain on the system after
6252 the package has been removed. Only when <prgn>dpkg</prgn>
6253 is executed with the <tt>--purge</tt> option will
6254 configuration files be removed. In particular, as the
6255 <file>/etc/init.d/<var>package</var></file> script itself is
6256 usually a <tt>conffile</tt>, it will remain on the system
6257 if the package is removed but not purged. Therefore, you
6258 should include a <tt>test</tt> statement at the top of the
6260 <example compact="compact">
6261 test -f <var>program-executed-later-in-script</var> || exit 0
6266 Often there are some variables in the <file>init.d</file>
6267 scripts whose values control the behavior of the scripts,
6268 and which a system administrator is likely to want to
6269 change. As the scripts themselves are frequently
6270 <tt>conffile</tt>s, modifying them requires that the
6271 administrator merge in their changes each time the package
6272 is upgraded and the <tt>conffile</tt> changes. To ease
6273 the burden on the system administrator, such configurable
6274 values should not be placed directly in the script.
6275 Instead, they should be placed in a file in
6276 <file>/etc/default</file>, which typically will have the same
6277 base name as the <file>init.d</file> script. This extra file
6278 should be sourced by the script when the script runs. It
6279 must contain only variable settings and comments in SUSv3
6280 <prgn>sh</prgn> format. It may either be a
6281 <tt>conffile</tt> or a configuration file maintained by
6282 the package maintainer scripts. See <ref id="config-files">
6287 To ensure that vital configurable values are always
6288 available, the <file>init.d</file> script should set default
6289 values for each of the shell variables it uses, either
6290 before sourcing the <file>/etc/default/</file> file or
6291 afterwards using something like the <tt>:
6292 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6293 script must behave sensibly and not fail if the
6294 <file>/etc/default</file> file is deleted.
6298 <file>/var/run</file> and <file>/var/lock</file> may be mounted
6299 as temporary filesystems<footnote>
6300 For example, using the <tt>RAMRUN</tt> and <tt>RAMLOCK</tt>
6301 options in <file>/etc/default/rcS</file>.
6302 </footnote>, so the <file>init.d</file> scripts must handle this
6303 correctly. This will typically amount to creating any required
6304 subdirectories dynamically when the <file>init.d</file> script
6305 is run, rather than including them in the package and relying on
6306 <prgn>dpkg</prgn> to create them.
6311 <heading>Interfacing with the initscript system</heading>
6314 Maintainers should use the abstraction layer provided by
6315 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6316 programs to deal with initscripts in their packages'
6317 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6318 and <prgn>postrm</prgn>.
6322 Directly managing the /etc/rc?.d links and directly
6323 invoking the <file>/etc/init.d/</file> initscripts should
6324 be done only by packages providing the initscript
6325 subsystem (such as <prgn>sysv-rc</prgn> and
6326 <prgn>file-rc</prgn>).
6330 <heading>Managing the links</heading>
6333 The program <prgn>update-rc.d</prgn> is provided for
6334 package maintainers to arrange for the proper creation and
6335 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6336 or their functional equivalent if another method is being
6337 used. This may be used by maintainers in their packages'
6338 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6342 You must not include any <file>/etc/rc<var>n</var>.d</file>
6343 symbolic links in the actual archive or manually create or
6344 remove the symbolic links in maintainer scripts; you must
6345 use the <prgn>update-rc.d</prgn> program instead. (The
6346 former will fail if an alternative method of maintaining
6347 runlevel information is being used.) You must not include
6348 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6349 in the archive either. (Only the <tt>sysvinit</tt>
6354 By default <prgn>update-rc.d</prgn> will start services in
6355 each of the multi-user state runlevels (2, 3, 4, and 5)
6356 and stop them in the halt runlevel (0), the single-user
6357 runlevel (1) and the reboot runlevel (6). The system
6358 administrator will have the opportunity to customize
6359 runlevels by simply adding, moving, or removing the
6360 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6361 symbolic links are being used, or by modifying
6362 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6367 To get the default behavior for your package, put in your
6368 <prgn>postinst</prgn> script
6369 <example compact="compact">
6370 update-rc.d <var>package</var> defaults
6372 and in your <prgn>postrm</prgn>
6373 <example compact="compact">
6374 if [ "$1" = purge ]; then
6375 update-rc.d <var>package</var> remove
6377 </example>. Note that if your package changes runlevels
6378 or priority, you may have to remove and recreate the links,
6379 since otherwise the old links may persist. Refer to the
6380 documentation of <prgn>update-rc.d</prgn>.
6384 This will use a default sequence number of 20. If it does
6385 not matter when or in which order the <file>init.d</file>
6386 script is run, use this default. If it does, then you
6387 should talk to the maintainer of the <prgn>sysvinit</prgn>
6388 package or post to <tt>debian-devel</tt>, and they will
6389 help you choose a number.
6393 For more information about using <tt>update-rc.d</tt>,
6394 please consult its man page <manref name="update-rc.d"
6400 <heading>Running initscripts</heading>
6402 The program <prgn>invoke-rc.d</prgn> is provided to make
6403 it easier for package maintainers to properly invoke an
6404 initscript, obeying runlevel and other locally-defined
6405 constraints that might limit a package's right to start,
6406 stop and otherwise manage services. This program may be
6407 used by maintainers in their packages' scripts.
6411 The package maintainer scripts must use
6412 <prgn>invoke-rc.d</prgn> to invoke the
6413 <file>/etc/init.d/*</file> initscripts, instead of
6414 calling them directly.
6418 By default, <prgn>invoke-rc.d</prgn> will pass any
6419 action requests (start, stop, reload, restart...) to the
6420 <file>/etc/init.d</file> script, filtering out requests
6421 to start or restart a service out of its intended
6426 Most packages will simply need to change:
6427 <example compact="compact">/etc/init.d/<package>
6428 <action></example> in their <prgn>postinst</prgn>
6429 and <prgn>prerm</prgn> scripts to:
6430 <example compact="compact">
6431 if which invoke-rc.d >/dev/null 2>&1; then
6432 invoke-rc.d <var>package</var> <action>
6434 /etc/init.d/<var>package</var> <action>
6440 A package should register its initscript services using
6441 <prgn>update-rc.d</prgn> before it tries to invoke them
6442 using <prgn>invoke-rc.d</prgn>. Invocation of
6443 unregistered services may fail.
6447 For more information about using
6448 <prgn>invoke-rc.d</prgn>, please consult its man page
6449 <manref name="invoke-rc.d" section="8">.
6455 <heading>Boot-time initialization</heading>
6458 There used to be another directory, <file>/etc/rc.boot</file>,
6459 which contained scripts which were run once per machine
6460 boot. This has been deprecated in favour of links from
6461 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6462 described in <ref id="/etc/init.d">. Packages must not
6463 place files in <file>/etc/rc.boot</file>.
6468 <heading>Example</heading>
6471 An example on which you can base your
6472 <file>/etc/init.d</file> scripts is found in
6473 <file>/etc/init.d/skeleton</file>.
6480 <heading>Console messages from <file>init.d</file> scripts</heading>
6483 This section describes the formats to be used for messages
6484 written to standard output by the <file>/etc/init.d</file>
6485 scripts. The intent is to improve the consistency of
6486 Debian's startup and shutdown look and feel. For this
6487 reason, please look very carefully at the details. We want
6488 the messages to have the same format in terms of wording,
6489 spaces, punctuation and case of letters.
6493 Here is a list of overall rules that should be used for
6494 messages generated by <file>/etc/init.d</file> scripts.
6500 The message should fit in one line (fewer than 80
6501 characters), start with a capital letter and end with
6502 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6506 If the script is performing some time consuming task in
6507 the background (not merely starting or stopping a
6508 program, for instance), an ellipsis (three dots:
6509 <tt>...</tt>) should be output to the screen, with no
6510 leading or tailing whitespace or line feeds.
6514 The messages should appear as if the computer is telling
6515 the user what it is doing (politely :-), but should not
6516 mention "it" directly. For example, instead of:
6517 <example compact="compact">
6518 I'm starting network daemons: nfsd mountd.
6520 the message should say
6521 <example compact="compact">
6522 Starting network daemons: nfsd mountd.
6529 <tt>init.d</tt> script should use the following standard
6530 message formats for the situations enumerated below.
6536 <p>When daemons are started</p>
6539 If the script starts one or more daemons, the output
6540 should look like this (a single line, no leading
6542 <example compact="compact">
6543 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6545 The <var>description</var> should describe the
6546 subsystem the daemon or set of daemons are part of,
6547 while <var>daemon-1</var> up to <var>daemon-n</var>
6548 denote each daemon's name (typically the file name of
6553 For example, the output of <file>/etc/init.d/lpd</file>
6555 <example compact="compact">
6556 Starting printer spooler: lpd.
6561 This can be achieved by saying
6562 <example compact="compact">
6563 echo -n "Starting printer spooler: lpd"
6564 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6567 in the script. If there are more than one daemon to
6568 start, the output should look like this:
6569 <example compact="compact">
6570 echo -n "Starting remote file system services:"
6571 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6572 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6573 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6576 This makes it possible for the user to see what is
6577 happening and when the final daemon has been started.
6578 Care should be taken in the placement of white spaces:
6579 in the example above the system administrators can
6580 easily comment out a line if they don't want to start
6581 a specific daemon, while the displayed message still
6587 <p>When a system parameter is being set</p>
6590 If you have to set up different system parameters
6591 during the system boot, you should use this format:
6592 <example compact="compact">
6593 Setting <var>parameter</var> to "<var>value</var>".
6598 You can use a statement such as the following to get
6600 <example compact="compact">
6601 echo "Setting DNS domainname to \"$domainname\"."
6606 Note that the same symbol (<tt>"</tt>) <!-- " --> is used
6607 for the left and right quotation marks. A grave accent
6608 (<tt>`</tt>) is not a quote character; neither is an
6609 apostrophe (<tt>'</tt>).
6614 <p>When a daemon is stopped or restarted</p>
6617 When you stop or restart a daemon, you should issue a
6618 message identical to the startup message, except that
6619 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6620 or <tt>Restarting</tt> respectively.
6624 For example, stopping the printer daemon will look like
6626 <example compact="compact">
6627 Stopping printer spooler: lpd.
6633 <p>When something is executed</p>
6636 There are several examples where you have to run a
6637 program at system startup or shutdown to perform a
6638 specific task, for example, setting the system's clock
6639 using <prgn>netdate</prgn> or killing all processes
6640 when the system shuts down. Your message should look
6642 <example compact="compact">
6643 Doing something very useful...done.
6645 You should print the <tt>done.</tt> immediately after
6646 the job has been completed, so that the user is
6647 informed why they have to wait. You can get this
6649 <example compact="compact">
6650 echo -n "Doing something very useful..."
6659 <p>When the configuration is reloaded</p>
6662 When a daemon is forced to reload its configuration
6663 files you should use the following format:
6664 <example compact="compact">
6665 Reloading <var>description</var> configuration...done.
6667 where <var>description</var> is the same as in the
6668 daemon starting message.
6676 <heading>Cron jobs</heading>
6679 Packages must not modify the configuration file
6680 <file>/etc/crontab</file>, and they must not modify the files in
6681 <file>/var/spool/cron/crontabs</file>.</p>
6684 If a package wants to install a job that has to be executed
6685 via cron, it should place a file with the name of the
6686 package in one or more of the following directories:
6687 <example compact="compact">
6693 As these directory names imply, the files within them are
6694 executed on an hourly, daily, weekly, or monthly basis,
6695 respectively. The exact times are listed in
6696 <file>/etc/crontab</file>.</p>
6699 All files installed in any of these directories must be
6700 scripts (e.g., shell scripts or Perl scripts) so that they
6701 can easily be modified by the local system administrator.
6702 In addition, they must be treated as configuration files.
6706 If a certain job has to be executed at some other frequency or
6707 at a specific time, the package should install a file
6708 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6709 same syntax as <file>/etc/crontab</file> and is processed by
6710 <prgn>cron</prgn> automatically. The file must also be
6711 treated as a configuration file. (Note that entries in the
6712 <file>/etc/cron.d</file> directory are not handled by
6713 <prgn>anacron</prgn>. Thus, you should only use this
6714 directory for jobs which may be skipped if the system is not
6717 Unlike <file>crontab</file> files described in the IEEE Std
6718 1003.1-2008 (POSIX.1) available from
6719 <url id="http://www.opengroup.org/onlinepubs/9699919799/"
6720 name="The Open Group">, the files in
6721 <file>/etc/cron.d</file> and the file
6722 <file>/etc/crontab</file> have seven fields; namely:
6724 <item>Minute [0,59]</item>
6725 <item>Hour [0,23]</item>
6726 <item>Day of the month [1,31]</item>
6727 <item>Month of the year [1,12]</item>
6728 <item>Day of the week ([0,6] with 0=Sunday)</item>
6729 <item>Username</item>
6730 <item>Command to be run</item>
6732 Ranges of numbers are allowed. Ranges are two numbers
6733 separated with a hyphen. The specified range is inclusive.
6734 Lists are allowed. A list is a set of numbers (or ranges)
6735 separated by commas. Step values can be used in conjunction
6740 The scripts or <tt>crontab</tt> entries in these directories should
6741 check if all necessary programs are installed before they
6742 try to execute them. Otherwise, problems will arise when a
6743 package was removed but not purged since configuration files
6744 are kept on the system in this situation.
6748 Any <tt>cron</tt> daemon must provide
6749 <file>/usr/bin/crontab</file> and support normal
6750 <tt>crontab</tt> entries as specified in POSIX. The daemon
6751 must also support names for days and months, ranges, and
6752 step values. It has to support <file>/etc/crontab</file>,
6753 and correctly execute the scripts in
6754 <file>/etc/cron.d</file>. The daemon must also correctly
6756 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>.
6761 <heading>Menus</heading>
6764 The Debian <tt>menu</tt> package provides a standard
6765 interface between packages providing applications and
6766 <em>menu programs</em> (either X window managers or
6767 text-based menu programs such as <prgn>pdmenu</prgn>).
6771 All packages that provide applications that need not be
6772 passed any special command line arguments for normal
6773 operation should register a menu entry for those
6774 applications, so that users of the <tt>menu</tt> package
6775 will automatically get menu entries in their window
6776 managers, as well in shells like <tt>pdmenu</tt>.
6780 Menu entries should follow the current menu policy.
6784 The menu policy can be found in the <tt>menu-policy</tt>
6785 files in the <tt>debian-policy</tt> package.
6786 It is also available from the Debian web mirrors at
6787 <tt><url name="/doc/packaging-manuals/menu-policy/"
6788 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6792 Please also refer to the <em>Debian Menu System</em>
6793 documentation that comes with the <package>menu</package>
6794 package for information about how to register your
6800 <heading>Multimedia handlers</heading>
6803 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6804 is a mechanism for encoding files and data streams and
6805 providing meta-information about them, in particular their
6806 type (e.g. audio or video) and format (e.g. PNG, HTML,
6811 Registration of MIME type handlers allows programs like mail
6812 user agents and web browsers to invoke these handlers to
6813 view, edit or display MIME types they don't support directly.
6817 Packages which provide the ability to view/show/play,
6818 compose, edit or print MIME types should register themselves
6819 as such following the current MIME support policy.
6823 The MIME support policy can be found in the <tt>mime-policy</tt>
6824 files in the <tt>debian-policy</tt> package.
6825 It is also available from the Debian web mirrors at
6826 <tt><url name="/doc/packaging-manuals/mime-policy/"
6827 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6833 <heading>Keyboard configuration</heading>
6836 To achieve a consistent keyboard configuration so that all
6837 applications interpret a keyboard event the same way, all
6838 programs in the Debian distribution must be configured to
6839 comply with the following guidelines.
6843 The following keys must have the specified interpretations:
6846 <tag><tt><--</tt></tag>
6847 <item>delete the character to the left of the cursor</item>
6849 <tag><tt>Delete</tt></tag>
6850 <item>delete the character to the right of the cursor</item>
6852 <tag><tt>Control+H</tt></tag>
6853 <item>emacs: the help prefix</item>
6856 The interpretation of any keyboard events should be
6857 independent of the terminal that is used, be it a virtual
6858 console, an X terminal emulator, an rlogin/telnet session,
6863 The following list explains how the different programs
6864 should be set up to achieve this:
6870 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6874 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6878 X translations are set up to make
6879 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6880 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6881 is the vt220 escape code for the "delete character"
6882 key). This must be done by loading the X resources
6883 using <prgn>xrdb</prgn> on all local X displays, not
6884 using the application defaults, so that the
6885 translation resources used correspond to the
6886 <prgn>xmodmap</prgn> settings.
6890 The Linux console is configured to make
6891 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6892 generate <tt>ESC [ 3 ~</tt>.
6896 X applications are configured so that <tt><</tt>
6897 deletes left, and <tt>Delete</tt> deletes right. Motif
6898 applications already work like this.
6902 Terminals should have <tt>stty erase ^?</tt> .
6906 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6907 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6908 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6912 Emacs is programmed to map <tt>KB_Backspace</tt> or
6913 the <tt>stty erase</tt> character to
6914 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6915 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6916 <tt>^H</tt> to <tt>help</tt> as always.
6920 Other applications use the <tt>stty erase</tt>
6921 character and <tt>kdch1</tt> for the two delete keys,
6922 with ASCII DEL being "delete previous character" and
6923 <tt>kdch1</tt> being "delete character under
6931 This will solve the problem except for the following
6938 Some terminals have a <tt><--</tt> key that cannot
6939 be made to produce anything except <tt>^H</tt>. On
6940 these terminals Emacs help will be unavailable on
6941 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6942 character takes precedence in Emacs, and has been set
6943 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6944 available) can be used instead.
6948 Some operating systems use <tt>^H</tt> for <tt>stty
6949 erase</tt>. However, modern telnet versions and all
6950 rlogin versions propagate <tt>stty</tt> settings, and
6951 almost all UNIX versions honour <tt>stty erase</tt>.
6952 Where the <tt>stty</tt> settings are not propagated
6953 correctly, things can be made to work by using
6954 <tt>stty</tt> manually.
6958 Some systems (including previous Debian versions) use
6959 <prgn>xmodmap</prgn> to arrange for both
6960 <tt><--</tt> and <tt>Delete</tt> to generate
6961 <tt>KB_Delete</tt>. We can change the behavior of
6962 their X clients using the same X resources that we use
6963 to do it for our own clients, or configure our clients
6964 using their resources when things are the other way
6965 around. On displays configured like this
6966 <tt>Delete</tt> will not work, but <tt><--</tt>
6971 Some operating systems have different <tt>kdch1</tt>
6972 settings in their <tt>terminfo</tt> database for
6973 <tt>xterm</tt> and others. On these systems the
6974 <tt>Delete</tt> key will not work correctly when you
6975 log in from a system conforming to our policy, but
6976 <tt><--</tt> will.
6983 <heading>Environment variables</heading>
6986 A program must not depend on environment variables to get
6987 reasonable defaults. (That's because these environment
6988 variables would have to be set in a system-wide
6989 configuration file like <file>/etc/profile</file>, which is not
6990 supported by all shells.)
6994 If a program usually depends on environment variables for its
6995 configuration, the program should be changed to fall back to
6996 a reasonable default configuration if these environment
6997 variables are not present. If this cannot be done easily
6998 (e.g., if the source code of a non-free program is not
6999 available), the program must be replaced by a small
7000 "wrapper" shell script which sets the environment variables
7001 if they are not already defined, and calls the original program.
7005 Here is an example of a wrapper script for this purpose:
7007 <example compact="compact">
7009 BAR=${BAR:-/var/lib/fubar}
7011 exec /usr/lib/foo/foo "$@"
7016 Furthermore, as <file>/etc/profile</file> is a configuration
7017 file of the <prgn>base-files</prgn> package, other packages must
7018 not put any environment variables or other commands into that
7023 <sect id="doc-base">
7024 <heading>Registering Documents using doc-base</heading>
7027 The <package>doc-base</package> package implements a
7028 flexible mechanism for handling and presenting
7029 documentation. The recommended practice is for every Debian
7030 package that provides online documentation (other than just
7031 manual pages) to register these documents with
7032 <package>doc-base</package> by installing a
7033 <package>doc-base</package> control file via the
7034 <prgn/install-docs/ script at installation time and
7035 de-register the manuals again when the package is removed.
7038 Please refer to the documentation that comes with the
7039 <package>doc-base</package> package for information and
7048 <heading>Files</heading>
7051 <heading>Binaries</heading>
7054 Two different packages must not install programs with
7055 different functionality but with the same filenames. (The
7056 case of two programs having the same functionality but
7057 different implementations is handled via "alternatives" or
7058 the "Conflicts" mechanism. See <ref id="maintscripts"> and
7059 <ref id="conflicts"> respectively.) If this case happens,
7060 one of the programs must be renamed. The maintainers should
7061 report this to the <tt>debian-devel</tt> mailing list and
7062 try to find a consensus about which program will have to be
7063 renamed. If a consensus cannot be reached, <em>both</em>
7064 programs must be renamed.
7068 By default, when a package is being built, any binaries
7069 created should include debugging information, as well as
7070 being compiled with optimization. You should also turn on
7071 as many reasonable compilation warnings as possible; this
7072 makes life easier for porters, who can then look at build
7073 logs for possible problems. For the C programming language,
7074 this means the following compilation parameters should be
7076 <example compact="compact">
7078 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
7080 INSTALL = install -s # (or use strip on the files in debian/tmp)
7085 Note that by default all installed binaries should be stripped,
7086 either by using the <tt>-s</tt> flag to
7087 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
7088 the binaries after they have been copied into
7089 <file>debian/tmp</file> but before the tree is made into a
7094 Although binaries in the build tree should be compiled with
7095 debugging information by default, it can often be difficult to
7096 debug programs if they are also subjected to compiler
7097 optimization. For this reason, it is recommended to support the
7098 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
7099 (see <ref id="debianrules-options">). This variable can contain
7100 several flags to change how a package is compiled and built.
7104 It is up to the package maintainer to decide what
7105 compilation options are best for the package. Certain
7106 binaries (such as computationally-intensive programs) will
7107 function better with certain flags (<tt>-O3</tt>, for
7108 example); feel free to use them. Please use good judgment
7109 here. Don't use flags for the sake of it; only use them
7110 if there is good reason to do so. Feel free to override
7111 the upstream author's ideas about which compilation
7112 options are best: they are often inappropriate for our
7118 <sect id="libraries">
7119 <heading>Libraries</heading>
7122 If the package is <strong>architecture: any</strong>, then
7123 the shared library compilation and linking flags must have
7124 <tt>-fPIC</tt>, or the package shall not build on some of
7125 the supported architectures<footnote>
7127 If you are using GCC, <tt>-fPIC</tt> produces code with
7128 relocatable position independent code, which is required for
7129 most architectures to create a shared library, with i386 and
7130 perhaps some others where non position independent code is
7131 permitted in a shared library.
7134 Position independent code may have a performance penalty,
7135 especially on <tt>i386</tt>. However, in most cases the
7136 speed penalty must be measured against the memory wasted on
7137 the few architectures where non position independent code is
7140 </footnote>. Any exception to this rule must be discussed on
7141 the mailing list <em>debian-devel@lists.debian.org</em>, and
7142 a rough consensus obtained. The reasons for not compiling
7143 with <tt>-fPIC</tt> flag must be recorded in the file
7144 <tt>README.Debian</tt>, and care must be taken to either
7145 restrict the architecture or arrange for <tt>-fPIC</tt> to
7146 be used on architectures where it is required.<footnote>
7148 Some of the reasons why this might be required is if the
7149 library contains hand crafted assembly code that is not
7150 relocatable, the speed penalty is excessive for compute
7151 intensive libs, and similar reasons.
7156 As to the static libraries, the common case is not to have
7157 relocatable code, since there is no benefit, unless in specific
7158 cases; therefore the static version must not be compiled
7159 with the <tt>-fPIC</tt> flag. Any exception to this rule
7160 should be discussed on the mailing list
7161 <em>debian-devel@lists.debian.org</em>, and the reasons for
7162 compiling with the <tt>-fPIC</tt> flag must be recorded in
7163 the file <tt>README.Debian</tt>. <footnote>
7165 Some of the reasons for linking static libraries with
7166 the <tt>-fPIC</tt> flag are if, for example, one needs a
7167 Perl API for a library that is under rapid development,
7168 and has an unstable API, so shared libraries are
7169 pointless at this phase of the library's development. In
7170 that case, since Perl needs a library with relocatable
7171 code, it may make sense to create a static library with
7172 relocatable code. Another reason cited is if you are
7173 distilling various libraries into a common shared
7174 library, like <tt>mklibs</tt> does in the Debian
7180 In other words, if both a shared and a static library is
7181 being built, each source unit (<tt>*.c</tt>, for example,
7182 for C files) will need to be compiled twice, for the normal
7186 You must specify the gcc option <tt>-D_REENTRANT</tt>
7187 when building a library (either static or shared) to make
7188 the library compatible with LinuxThreads.
7192 Although not enforced by the build tools, shared libraries
7193 must be linked against all libraries that they use symbols from
7194 in the same way that binaries are. This ensures the correct
7195 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
7196 system and guarantees that all libraries can be safely opened
7197 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
7198 option <tt>-Wl,-z,defs</tt> when building a shared library.
7199 Since this option enforces symbol resolution at build time,
7200 a missing library reference will be caught early as a fatal
7205 All installed shared libraries should be stripped with
7206 <example compact="compact">
7207 strip --strip-unneeded <var>your-lib</var>
7209 (The option <tt>--strip-unneeded</tt> makes
7210 <prgn>strip</prgn> remove only the symbols which aren't
7211 needed for relocation processing.) Shared libraries can
7212 function perfectly well when stripped, since the symbols for
7213 dynamic linking are in a separate part of the ELF object
7215 You might also want to use the options
7216 <tt>--remove-section=.comment</tt> and
7217 <tt>--remove-section=.note</tt> on both shared libraries
7218 and executables, and <tt>--strip-debug</tt> on static
7224 Note that under some circumstances it may be useful to
7225 install a shared library unstripped, for example when
7226 building a separate package to support debugging.
7230 Shared object files (often <file>.so</file> files) that are not
7231 public libraries, that is, they are not meant to be linked
7232 to by third party executables (binaries of other packages),
7233 should be installed in subdirectories of the
7234 <file>/usr/lib</file> directory. Such files are exempt from the
7235 rules that govern ordinary shared libraries, except that
7236 they must not be installed executable and should be
7238 A common example are the so-called "plug-ins",
7239 internal shared objects that are dynamically loaded by
7240 programs using <manref name="dlopen" section="3">.
7245 An ever increasing number of packages are using
7246 <prgn>libtool</prgn> to do their linking. The latest GNU
7247 libtools (>= 1.3a) can take advantage of the metadata in the
7248 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
7249 files). The main advantage of <prgn>libtool</prgn>'s
7250 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
7251 store and subsequently access metadata with respect to the
7252 libraries it builds. <prgn>libtool</prgn> will search for
7253 those files, which contain a lot of useful information about
7254 a library (such as library dependency information for static
7255 linking). Also, they're <em>essential</em> for programs
7256 using <tt>libltdl</tt>.<footnote>
7257 Although <prgn>libtool</prgn> is fully capable of
7258 linking against shared libraries which don't have
7259 <tt>.la</tt> files, as it is a mere shell script it can
7260 add considerably to the build time of a
7261 <prgn>libtool</prgn>-using package if that shell script
7262 has to derive all this information from first principles
7263 for each library every time it is linked. With the
7264 advent of <prgn>libtool</prgn> version 1.4 (and to a
7265 lesser extent <prgn>libtool</prgn> version 1.3), the
7266 <file>.la</file> files also store information about
7267 inter-library dependencies which cannot necessarily be
7268 derived after the <file>.la</file> file is deleted.
7273 Packages that use <prgn>libtool</prgn> to create shared
7274 libraries should include the <file>.la</file> files in the
7275 <tt>-dev</tt> package, unless the package relies on
7276 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
7277 the <tt>.la</tt> files must go in the run-time library
7282 You must make sure that you use only released versions of
7283 shared libraries to build your packages; otherwise other
7284 users will not be able to run your binaries
7285 properly. Producing source packages that depend on
7286 unreleased compilers is also usually a bad
7293 <heading>Shared libraries</heading>
7295 This section has moved to <ref id="sharedlibs">.
7301 <heading>Scripts</heading>
7304 All command scripts, including the package maintainer
7305 scripts inside the package and used by <prgn>dpkg</prgn>,
7306 should have a <tt>#!</tt> line naming the shell to be used
7311 In the case of Perl scripts this should be
7312 <tt>#!/usr/bin/perl</tt>.
7316 When scripts are installed into a directory in the system
7317 PATH, the script name should not include an extension such
7318 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7319 language currently used to implement it.
7322 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>) other than
7323 <file>init.d</file> scripts should almost certainly start
7324 with <tt>set -e</tt> so that errors are detected.
7325 <file>init.d</file> scripts are something of a special case, due
7326 to how frequently they need to call commands that are allowed to
7327 fail, and it may instead be easier to check the exit status of
7328 commands directly. See <ref id="writing-init"> for more
7329 information about writing <file>init.d</file> scripts.
7332 Every script should use <tt>set -e</tt> or check the exit status
7333 of <em>every</em> command.
7336 Scripts may assume that <file>/bin/sh</file> implements the
7337 SUSv3 Shell Command Language<footnote>
7338 Single UNIX Specification, version 3, which is also IEEE
7339 1003.1-2004 (POSIX), and is available on the World Wide Web
7340 from <url id="http://www.unix.org/version3/online.html"
7341 name="The Open Group"> after free
7342 registration.</footnote>
7343 plus the following additional features not mandated by
7345 These features are in widespread use in the Linux community
7346 and are implemented in all of bash, dash, and ksh, the most
7347 common shells users may wish to use as <file>/bin/sh</file>.
7350 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7351 must not generate a newline.</item>
7352 <item><tt>test</tt>, if implemented as a shell built-in, must
7353 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7355 <item><tt>local</tt> to create a scoped variable must be
7356 supported, including listing multiple variables in a single
7357 local command and assigning a value to a variable at the
7358 same time as localizing it. <tt>local</tt> may or
7359 may not preserve the variable value from an outer scope if
7360 no assignment is present. Uses such as:
7364 # ... use a, b, c, d ...
7367 must be supported and must set the value of <tt>c</tt> to
7371 If a shell script requires non-SUSv3 features from the shell
7372 interpreter other than those listed above, the appropriate shell
7373 must be specified in the first line of the script (e.g.,
7374 <tt>#!/bin/bash</tt>) and the package must depend on the package
7375 providing the shell (unless the shell package is marked
7376 "Essential", as in the case of <prgn>bash</prgn>).
7380 You may wish to restrict your script to SUSv3 features plus the
7381 above set when possible so that it may use <file>/bin/sh</file>
7382 as its interpreter. If your script works with <prgn>dash</prgn>
7383 (originally called <prgn>ash</prgn>), it probably complies with
7384 the above requirements, but if you are in doubt, use
7385 <file>/bin/bash</file>.
7389 Perl scripts should check for errors when making any
7390 system calls, including <tt>open</tt>, <tt>print</tt>,
7391 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7395 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7396 scripting languages. See <em>Csh Programming Considered
7397 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7398 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7399 If an upstream package comes with <prgn>csh</prgn> scripts
7400 then you must make sure that they start with
7401 <tt>#!/bin/csh</tt> and make your package depend on the
7402 <prgn>c-shell</prgn> virtual package.
7406 Any scripts which create files in world-writeable
7407 directories (e.g., in <file>/tmp</file>) must use a
7408 mechanism which will fail atomically if a file with the same
7409 name already exists.
7413 The Debian base system provides the <prgn>tempfile</prgn>
7414 and <prgn>mktemp</prgn> utilities for use by scripts for
7421 <heading>Symbolic links</heading>
7424 In general, symbolic links within a top-level directory
7425 should be relative, and symbolic links pointing from one
7426 top-level directory into another should be absolute. (A
7427 top-level directory is a sub-directory of the root
7428 directory <file>/</file>.)
7432 In addition, symbolic links should be specified as short as
7433 possible, i.e., link targets like <file>foo/../bar</file> are
7438 Note that when creating a relative link using
7439 <prgn>ln</prgn> it is not necessary for the target of the
7440 link to exist relative to the working directory you're
7441 running <prgn>ln</prgn> from, nor is it necessary to change
7442 directory to the directory where the link is to be made.
7443 Simply include the string that should appear as the target
7444 of the link (this will be a pathname relative to the
7445 directory in which the link resides) as the first argument
7450 For example, in your <prgn>Makefile</prgn> or
7451 <file>debian/rules</file>, you can do things like:
7452 <example compact="compact">
7453 ln -fs gcc $(prefix)/bin/cc
7454 ln -fs gcc debian/tmp/usr/bin/cc
7455 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7456 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7461 A symbolic link pointing to a compressed file should always
7462 have the same file extension as the referenced file. (For
7463 example, if a file <file>foo.gz</file> is referenced by a
7464 symbolic link, the filename of the link has to end with
7465 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7470 <heading>Device files</heading>
7473 Packages must not include device files or named pipes in the
7478 If a package needs any special device files that are not
7479 included in the base system, it must call
7480 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7481 after notifying the user<footnote>
7482 This notification could be done via a (low-priority)
7483 debconf message, or an echo (printf) statement.
7488 Packages must not remove any device files in the
7489 <prgn>postrm</prgn> or any other script. This is left to the
7490 system administrator.
7494 Debian uses the serial devices
7495 <file>/dev/ttyS*</file>. Programs using the old
7496 <file>/dev/cu*</file> devices should be changed to use
7497 <file>/dev/ttyS*</file>.
7501 Named pipes needed by the package must be created in
7502 the <prgn>postinst</prgn> script<footnote>
7503 It's better to use <prgn>mkfifo</prgn> rather
7504 than <prgn>mknod</prgn> to create named pipes so that
7505 automated checks for packages incorrectly creating device
7506 files with <prgn>mknod</prgn> won't have false positives.
7507 </footnote> and removed in
7508 the <prgn>prerm</prgn> or <prgn>postrm</prgn> script as
7513 <sect id="config-files">
7514 <heading>Configuration files</heading>
7517 <heading>Definitions</heading>
7521 <tag>configuration file</tag>
7523 A file that affects the operation of a program, or
7524 provides site- or host-specific information, or
7525 otherwise customizes the behavior of a program.
7526 Typically, configuration files are intended to be
7527 modified by the system administrator (if needed or
7528 desired) to conform to local policy or to provide
7529 more useful site-specific behavior.
7532 <tag><tt>conffile</tt></tag>
7534 A file listed in a package's <tt>conffiles</tt>
7535 file, and is treated specially by <prgn>dpkg</prgn>
7536 (see <ref id="configdetails">).
7542 The distinction between these two is important; they are
7543 not interchangeable concepts. Almost all
7544 <tt>conffile</tt>s are configuration files, but many
7545 configuration files are not <tt>conffiles</tt>.
7549 As noted elsewhere, <file>/etc/init.d</file> scripts,
7550 <file>/etc/default</file> files, scripts installed in
7551 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7552 configuration installed in <file>/etc/cron.d</file> must be
7553 treated as configuration files. In general, any script that
7554 embeds configuration information is de-facto a configuration
7555 file and should be treated as such.
7560 <heading>Location</heading>
7563 Any configuration files created or used by your package
7564 must reside in <file>/etc</file>. If there are several,
7565 consider creating a subdirectory of <file>/etc</file>
7566 named after your package.
7570 If your package creates or uses configuration files
7571 outside of <file>/etc</file>, and it is not feasible to modify
7572 the package to use <file>/etc</file> directly, put the files
7573 in <file>/etc</file> and create symbolic links to those files
7574 from the location that the package requires.
7579 <heading>Behavior</heading>
7582 Configuration file handling must conform to the following
7584 <list compact="compact">
7586 local changes must be preserved during a package
7590 configuration files must be preserved when the
7591 package is removed, and only deleted when the
7595 Obsolete configuration files without local changes may be
7596 removed by the package during upgrade.
7600 The easy way to achieve this behavior is to make the
7601 configuration file a <tt>conffile</tt>. This is
7602 appropriate only if it is possible to distribute a default
7603 version that will work for most installations, although
7604 some system administrators may choose to modify it. This
7605 implies that the default version will be part of the
7606 package distribution, and must not be modified by the
7607 maintainer scripts during installation (or at any other
7612 In order to ensure that local changes are preserved
7613 correctly, no package may contain or make hard links to
7614 conffiles.<footnote>
7615 Rationale: There are two problems with hard links.
7616 The first is that some editors break the link while
7617 editing one of the files, so that the two files may
7618 unwittingly become unlinked and different. The second
7619 is that <prgn>dpkg</prgn> might break the hard link
7620 while upgrading <tt>conffile</tt>s.
7625 The other way to do it is via the maintainer scripts. In
7626 this case, the configuration file must not be listed as a
7627 <tt>conffile</tt> and must not be part of the package
7628 distribution. If the existence of a file is required for
7629 the package to be sensibly configured it is the
7630 responsibility of the package maintainer to provide
7631 maintainer scripts which correctly create, update and
7632 maintain the file and remove it on purge. (See <ref
7633 id="maintainerscripts"> for more information.) These
7634 scripts must be idempotent (i.e., must work correctly if
7635 <prgn>dpkg</prgn> needs to re-run them due to errors
7636 during installation or removal), must cope with all the
7637 variety of ways <prgn>dpkg</prgn> can call maintainer
7638 scripts, must not overwrite or otherwise mangle the user's
7639 configuration without asking, must not ask unnecessary
7640 questions (particularly during upgrades), and must
7641 otherwise be good citizens.
7645 The scripts are not required to configure every possible
7646 option for the package, but only those necessary to get
7647 the package running on a given system. Ideally the
7648 sysadmin should not have to do any configuration other
7649 than that done (semi-)automatically by the
7650 <prgn>postinst</prgn> script.
7654 A common practice is to create a script called
7655 <file><var>package</var>-configure</file> and have the
7656 package's <prgn>postinst</prgn> call it if and only if the
7657 configuration file does not already exist. In certain
7658 cases it is useful for there to be an example or template
7659 file which the maintainer scripts use. Such files should
7660 be in <file>/usr/share/<var>package</var></file> or
7661 <file>/usr/lib/<var>package</var></file> (depending on whether
7662 they are architecture-independent or not). There should
7663 be symbolic links to them from
7664 <file>/usr/share/doc/<var>package</var>/examples</file> if
7665 they are examples, and should be perfectly ordinary
7666 <prgn>dpkg</prgn>-handled files (<em>not</em>
7667 configuration files).
7671 These two styles of configuration file handling must
7672 not be mixed, for that way lies madness:
7673 <prgn>dpkg</prgn> will ask about overwriting the file
7674 every time the package is upgraded.
7679 <heading>Sharing configuration files</heading>
7682 Packages which specify the same file as a
7683 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7684 with each other. (This is an instance of the general rule
7685 about not sharing files. Note that neither alternatives
7686 nor diversions are likely to be appropriate in this case;
7687 in particular, <prgn>dpkg</prgn> does not handle diverted
7688 <tt>conffile</tt>s well.)
7692 The maintainer scripts must not alter a <tt>conffile</tt>
7693 of <em>any</em> package, including the one the scripts
7698 If two or more packages use the same configuration file
7699 and it is reasonable for both to be installed at the same
7700 time, one of these packages must be defined as
7701 <em>owner</em> of the configuration file, i.e., it will be
7702 the package which handles that file as a configuration
7703 file. Other packages that use the configuration file must
7704 depend on the owning package if they require the
7705 configuration file to operate. If the other package will
7706 use the configuration file if present, but is capable of
7707 operating without it, no dependency need be declared.
7711 If it is desirable for two or more related packages to
7712 share a configuration file <em>and</em> for all of the
7713 related packages to be able to modify that configuration
7714 file, then the following should be done:
7715 <enumlist compact="compact">
7717 One of the related packages (the "owning" package)
7718 will manage the configuration file with maintainer
7719 scripts as described in the previous section.
7722 The owning package should also provide a program
7723 that the other packages may use to modify the
7727 The related packages must use the provided program
7728 to make any desired modifications to the
7729 configuration file. They should either depend on
7730 the core package to guarantee that the configuration
7731 modifier program is available or accept gracefully
7732 that they cannot modify the configuration file if it
7733 is not. (This is in addition to the fact that the
7734 configuration file may not even be present in the
7741 Sometimes it's appropriate to create a new package which
7742 provides the basic infrastructure for the other packages
7743 and which manages the shared configuration files. (The
7744 <tt>sgml-base</tt> package is a good example.)
7749 <heading>User configuration files ("dotfiles")</heading>
7752 The files in <file>/etc/skel</file> will automatically be
7753 copied into new user accounts by <prgn>adduser</prgn>.
7754 No other program should reference the files in
7755 <file>/etc/skel</file>.
7759 Therefore, if a program needs a dotfile to exist in
7760 advance in <file>$HOME</file> to work sensibly, that dotfile
7761 should be installed in <file>/etc/skel</file> and treated as a
7766 However, programs that require dotfiles in order to
7767 operate sensibly are a bad thing, unless they do create
7768 the dotfiles themselves automatically.
7772 Furthermore, programs should be configured by the Debian
7773 default installation to behave as closely to the upstream
7774 default behavior as possible.
7778 Therefore, if a program in a Debian package needs to be
7779 configured in some way in order to operate sensibly, that
7780 should be done using a site-wide configuration file placed
7781 in <file>/etc</file>. Only if the program doesn't support a
7782 site-wide default configuration and the package maintainer
7783 doesn't have time to add it may a default per-user file be
7784 placed in <file>/etc/skel</file>.
7788 <file>/etc/skel</file> should be as empty as we can make it.
7789 This is particularly true because there is no easy (or
7790 necessarily desirable) mechanism for ensuring that the
7791 appropriate dotfiles are copied into the accounts of
7792 existing users when a package is installed.
7798 <heading>Log files</heading>
7800 Log files should usually be named
7801 <file>/var/log/<var>package</var>.log</file>. If you have many
7802 log files, or need a separate directory for permission
7803 reasons (<file>/var/log</file> is writable only by
7804 <file>root</file>), you should usually create a directory named
7805 <file>/var/log/<var>package</var></file> and place your log
7810 Log files must be rotated occasionally so that they don't
7811 grow indefinitely; the best way to do this is to drop a log
7812 rotation configuration file into the directory
7813 <file>/etc/logrotate.d</file> and use the facilities provided by
7814 logrotate.<footnote>
7816 The traditional approach to log files has been to set up
7817 <em>ad hoc</em> log rotation schemes using simple shell
7818 scripts and cron. While this approach is highly
7819 customizable, it requires quite a lot of sysadmin work.
7820 Even though the original Debian system helped a little
7821 by automatically installing a system which can be used
7822 as a template, this was deemed not enough.
7826 The use of <prgn>logrotate</prgn>, a program developed
7827 by Red Hat, is better, as it centralizes log management.
7828 It has both a configuration file
7829 (<file>/etc/logrotate.conf</file>) and a directory where
7830 packages can drop their individual log rotation
7831 configurations (<file>/etc/logrotate.d</file>).
7834 Here is a good example for a logrotate config
7835 file (for more information see <manref name="logrotate"
7837 <example compact="compact">
7838 /var/log/foo/*.log {
7843 /etc/init.d/foo force-reload
7847 This rotates all files under <file>/var/log/foo</file>, saves 12
7848 compressed generations, and forces the daemon to reload its
7849 configuration information after the log rotation.
7853 Log files should be removed when the package is
7854 purged (but not when it is only removed). This should be
7855 done by the <prgn>postrm</prgn> script when it is called
7856 with the argument <tt>purge</tt> (see <ref
7857 id="removedetails">).
7862 <heading>Permissions and owners</heading>
7865 The rules in this section are guidelines for general use.
7866 If necessary you may deviate from the details below.
7867 However, if you do so you must make sure that what is done
7868 is secure and you should try to be as consistent as possible
7869 with the rest of the system. You should probably also
7870 discuss it on <prgn>debian-devel</prgn> first.
7874 Files should be owned by <tt>root:root</tt>, and made
7875 writable only by the owner and universally readable (and
7876 executable, if appropriate), that is mode 644 or 755.
7880 Directories should be mode 755 or (for group-writability)
7881 mode 2775. The ownership of the directory should be
7882 consistent with its mode: if a directory is mode 2775, it
7883 should be owned by the group that needs write access to
7886 When a package is upgraded, and the owner or permissions
7887 of a file included in the package has changed, dpkg
7888 arranges for the ownership and permissions to be
7889 correctly set upon installation. However, this does not
7890 extend to directories; the permissions and ownership of
7891 directories already on the system does not change on
7892 install or upgrade of packages. This makes sense, since
7893 otherwise common directories like <tt>/usr</tt> would
7894 always be in flux. To correctly change permissions of a
7895 directory the package owns, explicit action is required,
7896 usually in the <tt>postinst</tt> script. Care must be
7897 taken to handle downgrades as well, in that case.
7904 Setuid and setgid executables should be mode 4755 or 2755
7905 respectively, and owned by the appropriate user or group.
7906 They should not be made unreadable (modes like 4711 or
7907 2711 or even 4111); doing so achieves no extra security,
7908 because anyone can find the binary in the freely available
7909 Debian package; it is merely inconvenient. For the same
7910 reason you should not restrict read or execute permissions
7911 on non-set-id executables.
7915 Some setuid programs need to be restricted to particular
7916 sets of users, using file permissions. In this case they
7917 should be owned by the uid to which they are set-id, and by
7918 the group which should be allowed to execute them. They
7919 should have mode 4754; again there is no point in making
7920 them unreadable to those users who must not be allowed to
7925 It is possible to arrange that the system administrator can
7926 reconfigure the package to correspond to their local
7927 security policy by changing the permissions on a binary:
7928 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7929 described below.<footnote>
7930 Ordinary files installed by <prgn>dpkg</prgn> (as
7931 opposed to <tt>conffile</tt>s and other similar objects)
7932 normally have their permissions reset to the distributed
7933 permissions when the package is reinstalled. However,
7934 the use of <prgn>dpkg-statoverride</prgn> overrides this
7937 Another method you should consider is to create a group for
7938 people allowed to use the program(s) and make any setuid
7939 executables executable only by that group.
7943 If you need to create a new user or group for your package
7944 there are two possibilities. Firstly, you may need to
7945 make some files in the binary package be owned by this
7946 user or group, or you may need to compile the user or
7947 group id (rather than just the name) into the binary
7948 (though this latter should be avoided if possible, as in
7949 this case you need a statically allocated id).</p>
7952 If you need a statically allocated id, you must ask for a
7953 user or group id from the <tt>base-passwd</tt> maintainer,
7954 and must not release the package until you have been
7955 allocated one. Once you have been allocated one you must
7956 either make the package depend on a version of the
7957 <tt>base-passwd</tt> package with the id present in
7958 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7959 your package to create the user or group itself with the
7960 correct id (using <tt>adduser</tt>) in its
7961 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7962 the <prgn>postinst</prgn> is to be preferred if it is
7963 possible, otherwise a pre-dependency will be needed on the
7964 <tt>adduser</tt> package.)
7968 On the other hand, the program might be able to determine
7969 the uid or gid from the user or group name at runtime, so
7970 that a dynamically allocated id can be used. In this case
7971 you should choose an appropriate user or group name,
7972 discussing this on <prgn>debian-devel</prgn> and checking
7973 with the <package/base-passwd/ maintainer that it is unique and that
7974 they do not wish you to use a statically allocated id
7975 instead. When this has been checked you must arrange for
7976 your package to create the user or group if necessary using
7977 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7978 <prgn>postinst</prgn> script (again, the latter is to be
7979 preferred if it is possible).
7983 Note that changing the numeric value of an id associated
7984 with a name is very difficult, and involves searching the
7985 file system for all appropriate files. You need to think
7986 carefully whether a static or dynamic id is required, since
7987 changing your mind later will cause problems.
7990 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7992 This section is not intended as policy, but as a
7993 description of the use of <prgn>dpkg-statoverride</prgn>.
7997 If a system administrator wishes to have a file (or
7998 directory or other such thing) installed with owner and
7999 permissions different from those in the distributed Debian
8000 package, they can use the <prgn>dpkg-statoverride</prgn>
8001 program to instruct <prgn>dpkg</prgn> to use the different
8002 settings every time the file is installed. Thus the
8003 package maintainer should distribute the files with their
8004 normal permissions, and leave it for the system
8005 administrator to make any desired changes. For example, a
8006 daemon which is normally required to be setuid root, but
8007 in certain situations could be used without being setuid,
8008 should be installed setuid in the <tt>.deb</tt>. Then the
8009 local system administrator can change this if they wish.
8010 If there are two standard ways of doing it, the package
8011 maintainer can use <tt>debconf</tt> to find out the
8012 preference, and call <prgn>dpkg-statoverride</prgn> in the
8013 maintainer script if necessary to accommodate the system
8014 administrator's choice. Care must be taken during
8015 upgrades to not override an existing setting.
8019 Given the above, <prgn>dpkg-statoverride</prgn> is
8020 essentially a tool for system administrators and would not
8021 normally be needed in the maintainer scripts. There is
8022 one type of situation, though, where calls to
8023 <prgn>dpkg-statoverride</prgn> would be needed in the
8024 maintainer scripts, and that involves packages which use
8025 dynamically allocated user or group ids. In such a
8026 situation, something like the following idiom can be very
8027 helpful in the package's <prgn>postinst</prgn>, where
8028 <tt>sysuser</tt> is a dynamically allocated id:
8030 for i in /usr/bin/foo /usr/sbin/bar
8032 # only do something when no setting exists
8033 if ! dpkg-statoverride --list $i >/dev/null 2>&1
8035 #include: debconf processing, question about foo and bar
8036 if [ "$RET" = "true" ] ; then
8037 dpkg-statoverride --update --add sysuser root 4755 $i
8042 The corresponding code to remove the override when the package
8045 for i in /usr/bin/foo /usr/sbin/bar
8047 if dpkg-statoverride --list $i >/dev/null 2>&1
8049 dpkg-statoverride --remove $i
8059 <chapt id="customized-programs">
8060 <heading>Customized programs</heading>
8062 <sect id="arch-spec">
8063 <heading>Architecture specification strings</heading>
8066 If a program needs to specify an <em>architecture specification
8067 string</em> in some place, it should select one of the strings
8068 provided by <tt>dpkg-architecture -L</tt>. The strings are in
8069 the format <tt><var>os</var>-<var>arch</var></tt>, though the OS
8070 part is sometimes elided, as when the OS is Linux.
8074 Note that we don't want to use
8075 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
8076 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
8077 since this would make our programs incompatible with other
8078 Linux distributions. We also don't use something like
8079 <tt><var>arch</var>-unknown-linux</tt>, since the
8080 <tt>unknown</tt> does not look very good.
8083 <sect1 id="arch-wildcard-spec">
8084 <heading>Architecture wildcards</heading>
8087 A package may specify an architecture wildcard. Architecture
8088 wildcards are in the format <tt>any</tt> (which matches every
8089 architecture), <tt><var>os</var></tt>-any, or
8090 any-<tt><var>cpu</var></tt>. <footnote>
8091 Internally, the package system normalizes the GNU triplets
8092 and the Debian arches into Debian arch triplets (which are
8093 kind of inverted GNU triplets), with the first component of
8094 the triplet representing the libc and ABI in use, and then
8095 does matching against those triplets. However, such
8096 triplets are an internal implementation detail that should
8097 not be used by packages directly. The libc and ABI portion
8098 is handled internally by the package system based on
8099 the <var>os</var> and <var>cpu</var>.
8106 <heading>Daemons</heading>
8109 The configuration files <file>/etc/services</file>,
8110 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
8111 by the <prgn>netbase</prgn> package and must not be modified
8116 If a package requires a new entry in one of these files, the
8117 maintainer should get in contact with the
8118 <prgn>netbase</prgn> maintainer, who will add the entries
8119 and release a new version of the <prgn>netbase</prgn>
8124 The configuration file <file>/etc/inetd.conf</file> must not be
8125 modified by the package's scripts except via the
8126 <prgn>update-inetd</prgn> script or the
8127 <file>DebianNet.pm</file> Perl module. See their documentation
8128 for details on how to add entries.
8132 If a package wants to install an example entry into
8133 <file>/etc/inetd.conf</file>, the entry must be preceded with
8134 exactly one hash character (<tt>#</tt>). Such lines are
8135 treated as "commented out by user" by the
8136 <prgn>update-inetd</prgn> script and are not changed or
8137 activated during package updates.
8142 <heading>Using pseudo-ttys and modifying wtmp, utmp and
8146 Some programs need to create pseudo-ttys. This should be done
8147 using Unix98 ptys if the C library supports it. The resulting
8148 program must not be installed setuid root, unless that
8149 is required for other functionality.
8153 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
8154 <file>/var/log/lastlog</file> must be installed writable by
8155 group <tt>utmp</tt>. Programs which need to modify those
8156 files must be installed setgid <tt>utmp</tt>.
8161 <heading>Editors and pagers</heading>
8164 Some programs have the ability to launch an editor or pager
8165 program to edit or display a text document. Since there are
8166 lots of different editors and pagers available in the Debian
8167 distribution, the system administrator and each user should
8168 have the possibility to choose their preferred editor and
8173 In addition, every program should choose a good default
8174 editor/pager if none is selected by the user or system
8179 Thus, every program that launches an editor or pager must
8180 use the EDITOR or PAGER environment variable to determine
8181 the editor or pager the user wishes to use. If these
8182 variables are not set, the programs <file>/usr/bin/editor</file>
8183 and <file>/usr/bin/pager</file> should be used, respectively.
8187 These two files are managed through the <prgn>dpkg</prgn>
8188 "alternatives" mechanism. Thus every package providing an
8189 editor or pager must call the
8190 <prgn>update-alternatives</prgn> script to register these
8195 If it is very hard to adapt a program to make use of the
8196 EDITOR or PAGER variables, that program may be configured to
8197 use <file>/usr/bin/sensible-editor</file> and
8198 <file>/usr/bin/sensible-pager</file> as the editor or pager
8199 program respectively. These are two scripts provided in the
8200 <package>sensible-utils</package> package that check the EDITOR
8201 and PAGER variables and launch the appropriate program, and fall
8202 back to <file>/usr/bin/editor</file>
8203 and <file>/usr/bin/pager</file> if the variable is not set.
8207 A program may also use the VISUAL environment variable to
8208 determine the user's choice of editor. If it exists, it
8209 should take precedence over EDITOR. This is in fact what
8210 <file>/usr/bin/sensible-editor</file> does.
8214 It is not required for a package to depend on
8215 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
8216 package to provide such virtual packages.<footnote>
8217 The Debian base system already provides an editor and a
8223 <sect id="web-appl">
8224 <heading>Web servers and applications</heading>
8227 This section describes the locations and URLs that should
8228 be used by all web servers and web applications in the
8235 Cgi-bin executable files are installed in the
8237 <example compact="compact">
8238 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
8240 and should be referred to as
8241 <example compact="compact">
8242 http://localhost/cgi-bin/<var>cgi-bin-name</var>
8248 <p>Access to HTML documents</p>
8251 HTML documents for a package are stored in
8252 <file>/usr/share/doc/<var>package</var></file>
8253 and can be referred to as
8254 <example compact="compact">
8255 http://localhost/doc/<var>package</var>/<var>filename</var>
8260 The web server should restrict access to the document
8261 tree so that only clients on the same host can read
8262 the documents. If the web server does not support such
8263 access controls, then it should not provide access at
8264 all, or ask about providing access during installation.
8269 <p>Access to images</p>
8271 It is recommended that images for a package be stored
8272 in <tt>/usr/share/images/<var>package</var></tt> and
8273 may be referred to through an alias <tt>/images/</tt>
8276 http://localhost/images/<package>/<filename>
8283 <p>Web Document Root</p>
8286 Web Applications should try to avoid storing files in
8287 the Web Document Root. Instead they should use the
8288 /usr/share/doc/<var>package</var> directory for
8289 documents and register the Web Application via the
8290 <package>doc-base</package> package. If access to the
8291 web document root is unavoidable then use
8292 <example compact="compact">
8295 as the Document Root. This might be just a symbolic
8296 link to the location where the system administrator
8297 has put the real document root.
8300 <item><p>Providing httpd and/or httpd-cgi</p>
8302 All web servers should provide the virtual package
8303 <tt>httpd</tt>. If a web server has CGI support it should
8304 provide <tt>httpd-cgi</tt> additionally.
8307 All web applications which do not contain CGI scripts should
8308 depend on <tt>httpd</tt>, all those web applications which
8309 <tt>do</tt> contain CGI scripts, should depend on
8317 <sect id="mail-transport-agents">
8318 <heading>Mail transport, delivery and user agents</heading>
8321 Debian packages which process electronic mail, whether mail
8322 user agents (MUAs) or mail transport agents (MTAs), must
8323 ensure that they are compatible with the configuration
8324 decisions below. Failure to do this may result in lost
8325 mail, broken <tt>From:</tt> lines, and other serious brain
8330 The mail spool is <file>/var/mail</file> and the interface to
8331 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8332 the FHS). On older systems, the mail spool may be
8333 physically located in <file>/var/spool/mail</file>, but all
8334 access to the mail spool should be via the
8335 <file>/var/mail</file> symlink. The mail spool is part of the
8336 base system and not part of the MTA package.
8340 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8341 programs (such as IMAP daemons) must lock the mailbox in an
8342 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8343 be combined with dot locking. To avoid deadlocks, a program
8344 should use <tt>fcntl()</tt> first and dot locking after
8345 this, or alternatively implement the two locking methods in
8346 a non blocking way<footnote>
8347 If it is not possible to establish both locks, the
8348 system shouldn't wait for the second lock to be
8349 established, but remove the first lock, wait a (random)
8350 time, and start over locking again.
8351 </footnote>. Using the functions <tt>maillock</tt> and
8352 <tt>mailunlock</tt> provided by the
8353 <tt>liblockfile*</tt><footnote>
8354 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8355 to use these functions.
8356 </footnote> packages is the recommended way to realize this.
8360 Mailboxes are generally either mode 600 and owned by
8361 <var>user</var> or mode 660 and owned by
8362 <tt><var>user</var>:mail</tt><footnote>
8363 There are two traditional permission schemes for mail spools:
8364 mode 600 with all mail delivery done by processes running as
8365 the destination user, or mode 660 and owned by group mail with
8366 mail delivery done by a process running as a system user in
8367 group mail. Historically, Debian required mode 660 mail
8368 spools to enable the latter model, but that model has become
8369 increasingly uncommon and the principle of least privilege
8370 indicates that mail systems that use the first model should
8371 use permissions of 600. If delivery to programs is permitted,
8372 it's easier to keep the mail system secure if the delivery
8373 agent runs as the destination user. Debian Policy therefore
8374 permits either scheme.
8375 </footnote>. The local system administrator may choose a
8376 different permission scheme; packages should not make
8377 assumptions about the permission and ownership of mailboxes
8378 unless required (such as when creating a new mailbox). A MUA
8379 may remove a mailbox (unless it has nonstandard permissions) in
8380 which case the MTA or another MUA must recreate it if needed.
8384 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8385 be setgid mail to do the locking mentioned above (and
8386 must obviously avoid accessing other users' mailboxes
8387 using this privilege).</p>
8390 <file>/etc/aliases</file> is the source file for the system mail
8391 aliases (e.g., postmaster, usenet, etc.), it is the one
8392 which the sysadmin and <prgn>postinst</prgn> scripts may
8393 edit. After <file>/etc/aliases</file> is edited the program or
8394 human editing it must call <prgn>newaliases</prgn>. All MTA
8395 packages must come with a <prgn>newaliases</prgn> program,
8396 even if it does nothing, but older MTA packages did not do
8397 this so programs should not fail if <prgn>newaliases</prgn>
8398 cannot be found. Note that because of this, all MTA
8399 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8400 <tt>Replaces: mail-transport-agent</tt> control file
8405 The convention of writing <tt>forward to
8406 <var>address</var></tt> in the mailbox itself is not
8407 supported. Use a <tt>.forward</tt> file instead.</p>
8410 The <prgn>rmail</prgn> program used by UUCP
8411 for incoming mail should be <file>/usr/sbin/rmail</file>.
8412 Likewise, <prgn>rsmtp</prgn>, for receiving
8413 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8417 If your package needs to know what hostname to use on (for
8418 example) outgoing news and mail messages which are generated
8419 locally, you should use the file <file>/etc/mailname</file>. It
8420 will contain the portion after the username and <tt>@</tt>
8421 (at) sign for email addresses of users on the machine
8422 (followed by a newline).
8426 Such a package should check for the existence of this file
8427 when it is being configured. If it exists, it should be
8428 used without comment, although an MTA's configuration script
8429 may wish to prompt the user even if it finds that this file
8430 exists. If the file does not exist, the package should
8431 prompt the user for the value (preferably using
8432 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8433 as well as using it in the package's configuration. The
8434 prompt should make it clear that the name will not just be
8435 used by that package. For example, in this situation the
8436 <tt>inn</tt> package could say something like:
8437 <example compact="compact">
8438 Please enter the "mail name" of your system. This is the
8439 hostname portion of the address to be shown on outgoing
8440 news and mail messages. The default is
8441 <var>syshostname</var>, your system's host name. Mail
8442 name ["<var>syshostname</var>"]:
8444 where <var>syshostname</var> is the output of <tt>hostname
8450 <heading>News system configuration</heading>
8453 All the configuration files related to the NNTP (news)
8454 servers and clients should be located under
8455 <file>/etc/news</file>.</p>
8458 There are some configuration issues that apply to a number
8459 of news clients and server packages on the machine. These
8463 <tag><file>/etc/news/organization</file></tag>
8465 A string which should appear as the
8466 organization header for all messages posted
8467 by NNTP clients on the machine
8470 <tag><file>/etc/news/server</file></tag>
8472 Contains the FQDN of the upstream NNTP
8473 server, or localhost if the local machine is
8478 Other global files may be added as required for cross-package news
8485 <heading>Programs for the X Window System</heading>
8488 <heading>Providing X support and package priorities</heading>
8491 Programs that can be configured with support for the X
8492 Window System must be configured to do so and must declare
8493 any package dependencies necessary to satisfy their
8494 runtime requirements when using the X Window System. If
8495 such a package is of higher priority than the X packages
8496 on which it depends, it is required that either the
8497 X-specific components be split into a separate package, or
8498 that an alternative version of the package, which includes
8499 X support, be provided, or that the package's priority be
8505 <heading>Packages providing an X server</heading>
8508 Packages that provide an X server that, directly or
8509 indirectly, communicates with real input and display
8510 hardware should declare in their control data that they
8511 provide the virtual package <tt>xserver</tt>.<footnote>
8512 This implements current practice, and provides an
8513 actual policy for usage of the <tt>xserver</tt>
8514 virtual package which appears in the virtual packages
8515 list. In a nutshell, X servers that interface
8516 directly with the display and input hardware or via
8517 another subsystem (e.g., GGI) should provide
8518 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8519 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8525 <heading>Packages providing a terminal emulator</heading>
8528 Packages that provide a terminal emulator for the X Window
8529 System which meet the criteria listed below should declare
8530 in their control data that they provide the virtual
8531 package <tt>x-terminal-emulator</tt>. They should also
8532 register themselves as an alternative for
8533 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8538 To be an <tt>x-terminal-emulator</tt>, a program must:
8539 <list compact="compact">
8541 Be able to emulate a DEC VT100 terminal, or a
8542 compatible terminal.
8546 Support the command-line option <tt>-e
8547 <var>command</var></tt>, which creates a new
8548 terminal window<footnote>
8549 "New terminal window" does not necessarily mean
8550 a new top-level X window directly parented by
8551 the window manager; it could, if the terminal
8552 emulator application were so coded, be a new
8553 "view" in a multiple-document interface (MDI).
8555 and runs the specified <var>command</var>,
8556 interpreting the entirety of the rest of the command
8557 line as a command to pass straight to exec, in the
8558 manner that <tt>xterm</tt> does.
8562 Support the command-line option <tt>-T
8563 <var>title</var></tt>, which creates a new terminal
8564 window with the window title <var>title</var>.
8571 <heading>Packages providing a window manager</heading>
8574 Packages that provide a window manager should declare in
8575 their control data that they provide the virtual package
8576 <tt>x-window-manager</tt>. They should also register
8577 themselves as an alternative for
8578 <file>/usr/bin/x-window-manager</file>, with a priority
8579 calculated as follows:
8580 <list compact="compact">
8582 Start with a priority of 20.
8586 If the window manager supports the Debian menu
8587 system, add 20 points if this support is available
8588 in the package's default configuration (i.e., no
8589 configuration files belonging to the system or user
8590 have to be edited to activate the feature); if
8591 configuration files must be modified, add only 10
8597 If the window manager complies with <url
8598 id="http://www.freedesktop.org/Standards/wm-spec"
8599 name="The Window Manager Specification Project">,
8600 written by the <url id="http://www.freedesktop.org/"
8601 name="Free Desktop Group">, add 40 points.
8605 If the window manager permits the X session to be
8606 restarted using a <em>different</em> window manager
8607 (without killing the X server) in its default
8608 configuration, add 10 points; otherwise add none.
8615 <heading>Packages providing fonts</heading>
8618 Packages that provide fonts for the X Window
8620 For the purposes of Debian Policy, a "font for the X
8621 Window System" is one which is accessed via X protocol
8622 requests. Fonts for the Linux console, for PostScript
8623 renderer, or any other purpose, do not fit this
8624 definition. Any tool which makes such fonts available
8625 to the X Window System, however, must abide by this
8628 must do a number of things to ensure that they are both
8629 available without modification of the X or font server
8630 configuration, and that they do not corrupt files used by
8631 other font packages to register information about
8635 Fonts of any type supported by the X Window System
8636 must be in a separate binary package from any
8637 executables, libraries, or documentation (except
8638 that specific to the fonts shipped, such as their
8639 license information). If one or more of the fonts
8640 so packaged are necessary for proper operation of
8641 the package with which they are associated the font
8642 package may be Recommended; if the fonts merely
8643 provide an enhancement, a Suggests relationship may
8644 be used. Packages must not Depend on font
8646 This is because the X server may retrieve fonts
8647 from the local file system or over the network
8648 from an X font server; the Debian package system
8649 is empowered to deal only with the local
8655 BDF fonts must be converted to PCF fonts with the
8656 <prgn>bdftopcf</prgn> utility (available in the
8657 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8658 placed in a directory that corresponds to their
8660 <list compact="compact">
8662 100 dpi fonts must be placed in
8663 <file>/usr/share/fonts/X11/100dpi/</file>.
8667 75 dpi fonts must be placed in
8668 <file>/usr/share/fonts/X11/75dpi/</file>.
8672 Character-cell fonts, cursor fonts, and other
8673 low-resolution fonts must be placed in
8674 <file>/usr/share/fonts/X11/misc/</file>.
8680 Type 1 fonts must be placed in
8681 <file>/usr/share/fonts/X11/Type1/</file>. If font
8682 metric files are available, they must be placed here
8687 Subdirectories of <file>/usr/share/fonts/X11/</file>
8688 other than those listed above must be neither
8689 created nor used. (The <file>PEX</file>, <file>CID</file>,
8690 <file>Speedo</file>, and <file>cyrillic</file> directories
8691 are excepted for historical reasons, but installation of
8692 files into these directories remains discouraged.)
8696 Font packages may, instead of placing files directly
8697 in the X font directories listed above, provide
8698 symbolic links in that font directory pointing to
8699 the files' actual location in the filesystem. Such
8700 a location must comply with the FHS.
8704 Font packages should not contain both 75dpi and
8705 100dpi versions of a font. If both are available,
8706 they should be provided in separate binary packages
8707 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8708 the names of the packages containing the
8709 corresponding fonts.
8713 Fonts destined for the <file>misc</file> subdirectory
8714 should not be included in the same package as 75dpi
8715 or 100dpi fonts; instead, they should be provided in
8716 a separate package with <tt>-misc</tt> appended to
8721 Font packages must not provide the files
8722 <file>fonts.dir</file>, <file>fonts.alias</file>, or
8723 <file>fonts.scale</file> in a font directory:
8726 <file>fonts.dir</file> files must not be provided at all.
8730 <file>fonts.alias</file> and <file>fonts.scale</file>
8731 files, if needed, should be provided in the
8733 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
8734 where <var>fontdir</var> is the name of the
8736 <file>/usr/share/fonts/X11/</file> where the
8737 package's corresponding fonts are stored
8738 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
8739 <var>package</var> is the name of the package
8740 that provides these fonts, and
8741 <var>extension</var> is either <tt>scale</tt>
8742 or <tt>alias</tt>, whichever corresponds to
8749 Font packages must declare a dependency on
8750 <tt>xfonts-utils</tt> in their control
8755 Font packages that provide one or more
8756 <file>fonts.scale</file> files as described above must
8757 invoke <prgn>update-fonts-scale</prgn> on each
8758 directory into which they installed fonts
8759 <em>before</em> invoking
8760 <prgn>update-fonts-dir</prgn> on that directory.
8761 This invocation must occur in both the
8762 <prgn>postinst</prgn> (for all arguments) and
8763 <prgn>postrm</prgn> (for all arguments except
8764 <tt>upgrade</tt>) scripts.
8768 Font packages that provide one or more
8769 <file>fonts.alias</file> files as described above must
8770 invoke <prgn>update-fonts-alias</prgn> on each
8771 directory into which they installed fonts. This
8772 invocation must occur in both the
8773 <prgn>postinst</prgn> (for all arguments) and
8774 <prgn>postrm</prgn> (for all arguments except
8775 <tt>upgrade</tt>) scripts.
8779 Font packages must invoke
8780 <prgn>update-fonts-dir</prgn> on each directory into
8781 which they installed fonts. This invocation must
8782 occur in both the <prgn>postinst</prgn> (for all
8783 arguments) and <prgn>postrm</prgn> (for all
8784 arguments except <tt>upgrade</tt>) scripts.
8788 Font packages must not provide alias names for the
8789 fonts they include which collide with alias names
8790 already in use by fonts already packaged.
8794 Font packages must not provide fonts with the same
8795 XLFD registry name as another font already packaged.
8801 <sect1 id="appdefaults">
8802 <heading>Application defaults files</heading>
8805 Application defaults files must be installed in the
8806 directory <file>/etc/X11/app-defaults/</file> (use of a
8807 localized subdirectory of <file>/etc/X11/</file> as described
8808 in the <em>X Toolkit Intrinsics - C Language
8809 Interface</em> manual is also permitted). They must be
8810 registered as <tt>conffile</tt>s or handled as
8811 configuration files.
8815 Customization of programs' X resources may also be
8816 supported with the provision of a file with the same name
8817 as that of the package placed in
8818 the <file>/etc/X11/Xresources/</file> directory, which
8819 must be registered as a <tt>conffile</tt> or handled as a
8820 configuration file.<footnote>
8821 Note that this mechanism is not the same as using
8822 app-defaults; app-defaults are tied to the client
8823 binary on the local file system, whereas X resources
8824 are stored in the X server and affect all connecting
8831 <heading>Installation directory issues</heading>
8834 Historically, packages using the X Window System used a
8835 separate set of installation directories from other packages.
8836 This practice has been discontinued and packages using the X
8837 Window System should now generally be installed in the same
8838 directories as any other package. Specifically, packages must
8839 not install files under the <file>/usr/X11R6/</file> directory
8840 and the <file>/usr/X11R6/</file> directory hierarchy should be
8841 regarded as obsolete.
8845 Include files previously installed under
8846 <file>/usr/X11R6/include/X11/</file> should be installed into
8847 <file>/usr/include/X11/</file>. For files previously
8848 installed into subdirectories of
8849 <file>/usr/X11R6/lib/X11/</file>, package maintainers should
8850 determine if subdirectories of <file>/usr/lib/</file> and
8851 <file>/usr/share/</file> can be used. If not, a subdirectory
8852 of <file>/usr/lib/X11/</file> should be used.
8856 Configuration files for window, display, or session managers
8857 or other applications that are tightly integrated with the X
8858 Window System may be placed in a subdirectory
8859 of <file>/etc/X11/</file> corresponding to the package name.
8860 Other X Window System applications should use
8861 the <file>/etc/</file> directory unless otherwise mandated by
8862 policy (such as for <ref id="appdefaults">).
8867 <heading>The OSF/Motif and OpenMotif libraries</heading>
8870 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8871 OpenMotif libraries</em><footnote>
8872 OSF/Motif and OpenMotif are collectively referred to as
8873 "Motif" in this policy document.
8875 should be compiled against and tested with LessTif (a free
8876 re-implementation of Motif) instead. If the maintainer
8877 judges that the program or programs do not work
8878 sufficiently well with LessTif to be distributed and
8879 supported, but do so when compiled against Motif, then two
8880 versions of the package should be created; one linked
8881 statically against Motif and with <tt>-smotif</tt>
8882 appended to the package name, and one linked dynamically
8883 against Motif and with <tt>-dmotif</tt> appended to the
8888 Both Motif-linked versions are dependent
8889 upon non-DFSG-compliant software and thus cannot be
8890 uploaded to the <em>main</em> distribution; if the
8891 software is itself DFSG-compliant it may be uploaded to
8892 the <em>contrib</em> distribution. While known existing
8893 versions of Motif permit unlimited redistribution of
8894 binaries linked against the library (whether statically or
8895 dynamically), it is the package maintainer's
8896 responsibility to determine whether this is permitted by
8897 the license of the copy of Motif in their possession.
8903 <heading>Perl programs and modules</heading>
8906 Perl programs and modules should follow the current Perl policy.
8910 The Perl policy can be found in the <tt>perl-policy</tt>
8911 files in the <tt>debian-policy</tt> package.
8912 It is also available from the Debian web mirrors at
8913 <tt><url name="/doc/packaging-manuals/perl-policy/"
8914 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8919 <heading>Emacs lisp programs</heading>
8922 Please refer to the "Debian Emacs Policy" for details of how to
8923 package emacs lisp programs.
8927 The Emacs policy is available in
8928 <file>debian-emacs-policy.gz</file> of the
8929 <package>emacsen-common</package> package.
8930 It is also available from the Debian web mirrors at
8931 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8932 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8937 <heading>Games</heading>
8940 The permissions on <file>/var/games</file> are mode 755, owner
8941 <tt>root</tt> and group <tt>root</tt>.
8945 Each game decides on its own security policy.</p>
8948 Games which require protected, privileged access to
8949 high-score files, saved games, etc., may be made
8950 set-<em>group</em>-id (mode 2755) and owned by
8951 <tt>root:games</tt>, and use files and directories with
8952 appropriate permissions (770 <tt>root:games</tt>, for
8953 example). They must not be made
8954 set-<em>user</em>-id, as this causes security problems. (If
8955 an attacker can subvert any set-user-id game they can
8956 overwrite the executable of any other, causing other players
8957 of these games to run a Trojan horse program. With a
8958 set-group-id game the attacker only gets access to less
8959 important game data, and if they can get at the other
8960 players' accounts at all it will take considerably more
8964 Some packages, for example some fortune cookie programs, are
8965 configured by the upstream authors to install with their
8966 data files or other static information made unreadable so
8967 that they can only be accessed through set-id programs
8968 provided. You should not do this in a Debian package: anyone can
8969 download the <file>.deb</file> file and read the data from it,
8970 so there is no point making the files unreadable. Not
8971 making the files unreadable also means that you don't have
8972 to make so many programs set-id, which reduces the risk of a
8976 As described in the FHS, binaries of games should be
8977 installed in the directory <file>/usr/games</file>. This also
8978 applies to games that use the X Window System. Manual pages
8979 for games (X and non-X games) should be installed in
8980 <file>/usr/share/man/man6</file>.</p>
8986 <heading>Documentation</heading>
8989 <heading>Manual pages</heading>
8992 You should install manual pages in <prgn>nroff</prgn> source
8993 form, in appropriate places under <file>/usr/share/man</file>.
8994 You should only use sections 1 to 9 (see the FHS for more
8995 details). You must not install a pre-formatted "cat page".
8999 Each program, utility, and function should have an
9000 associated manual page included in the same package. It is
9001 suggested that all configuration files also have a manual
9002 page included as well. Manual pages for protocols and other
9003 auxiliary things are optional.
9007 If no manual page is available, this is considered as a bug
9008 and should be reported to the Debian Bug Tracking System (the
9009 maintainer of the package is allowed to write this bug report
9010 themselves, if they so desire). Do not close the bug report
9011 until a proper man page is available.<footnote>
9012 It is not very hard to write a man page. See the
9013 <url id="http://www.schweikhardt.net/man_page_howto.html"
9014 name="Man-Page-HOWTO">,
9015 <manref name="man" section="7">, the examples
9016 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
9017 the helper program <prgn>help2man</prgn>, or the
9018 directory <file>/usr/share/doc/man-db/examples</file>.
9023 You may forward a complaint about a missing man page to the
9024 upstream authors, and mark the bug as forwarded in the
9025 Debian bug tracking system. Even though the GNU Project do
9026 not in general consider the lack of a man page to be a bug,
9027 we do; if they tell you that they don't consider it a bug
9028 you should leave the bug in our bug tracking system open
9033 Manual pages should be installed compressed using <tt>gzip -9</tt>.
9037 If one man page needs to be accessible via several names it
9038 is better to use a symbolic link than the <file>.so</file>
9039 feature, but there is no need to fiddle with the relevant
9040 parts of the upstream source to change from <file>.so</file> to
9041 symlinks: don't do it unless it's easy. You should not
9042 create hard links in the manual page directories, nor put
9043 absolute filenames in <file>.so</file> directives. The filename
9044 in a <file>.so</file> in a man page should be relative to the
9045 base of the man page tree (usually
9046 <file>/usr/share/man</file>). If you do not create any links
9047 (whether symlinks, hard links, or <tt>.so</tt> directives)
9048 in the file system to the alternate names of the man page,
9049 then you should not rely on <prgn>man</prgn> finding your
9050 man page under those names based solely on the information in
9051 the man page's header.<footnote>
9052 Supporting this in <prgn>man</prgn> often requires
9053 unreasonable processing time to find a manual page or to
9054 report that none exists, and moves knowledge into man's
9055 database that would be better left in the file system.
9056 This support is therefore deprecated and will cease to
9057 be present in the future.
9062 Manual pages in locale-specific subdirectories of
9063 <file>/usr/share/man</file> should use either UTF-8 or the usual
9064 legacy encoding for that language (normally the one corresponding
9065 to the shortest relevant locale name in
9066 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
9067 <file>/usr/share/man/fr</file> should use either UTF-8 or
9068 ISO-8859-1.<footnote>
9069 <prgn>man</prgn> will automatically detect whether UTF-8 is in
9070 use. In future, all manual pages will be required to use
9076 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
9077 included in the subdirectory name unless it indicates a
9078 significant difference in the language, as this excludes
9079 speakers of the language in other countries.<footnote>
9080 At the time of writing, Chinese and Portuguese are the main
9081 languages with such differences, so <file>pt_BR</file>,
9082 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
9087 If a localized version of a manual page is provided, it should
9088 either be up-to-date or it should be obvious to the reader that
9089 it is outdated and the original manual page should be used
9090 instead. This can be done either by a note at the beginning of
9091 the manual page or by showing the missing or changed portions in
9092 the original language instead of the target language.
9097 <heading>Info documents</heading>
9100 Info documents should be installed in <file>/usr/share/info</file>.
9101 They should be compressed with <tt>gzip -9</tt>.
9105 The <prgn>install-info</prgn> program maintains a directory of
9106 installed info documents in <file>/usr/share/info/dir</file> for
9107 the use of info readers.<footnote>
9108 It was previously necessary for packages installing info
9109 documents to run <prgn>install-info</prgn> from maintainer
9110 scripts. This is no longer necessary. The installation
9111 system now uses dpkg triggers.
9113 This file must not be included in packages. Packages containing
9114 info documents should depend on <tt>dpkg (>= 1.15.4) |
9115 install-info</tt> to ensure that the directory file is properly
9116 rebuilt during partial upgrades from Debian 5.0 (lenny) and
9121 Info documents should contain section and directory entry
9122 information in the document for the use
9123 of <prgn>install-info</prgn>. The section should be specified
9124 via a line starting with <tt>INFO-DIR-SECTION</tt> followed by a
9125 space and the section of this info page. The directory entry or
9126 entries should be included between
9127 a <tt>START-INFO-DIR-ENTRY</tt> line and
9128 an <tt>END-INFO-DIR-ENTRY</tt> line. For example:
9130 INFO-DIR-SECTION Individual utilities
9131 START-INFO-DIR-ENTRY
9132 * example: (example). An example info directory entry.
9135 To determine which section to use, you should look
9136 at <file>/usr/share/info/dir</file> on your system and choose
9137 the most relevant (or create a new section if none of the
9138 current sections are relevant).<footnote>
9139 Normally, info documents are generated from Texinfo source.
9140 To include this information in the generated info document, if
9141 it is absent, add commands like:
9143 @dircategory Individual utilities
9145 * example: (example). An example info directory entry.
9148 to the Texinfo source of the document and ensure that the info
9149 documents are rebuilt from source during the package build.
9155 <heading>Additional documentation</heading>
9158 Any additional documentation that comes with the package may
9159 be installed at the discretion of the package maintainer.
9160 Plain text documentation should be installed in the directory
9161 <file>/usr/share/doc/<var>package</var></file>, where
9162 <var>package</var> is the name of the package, and
9163 compressed with <tt>gzip -9</tt> unless it is small.
9167 If a package comes with large amounts of documentation which
9168 many users of the package will not require you should create
9169 a separate binary package to contain it, so that it does not
9170 take up disk space on the machines of users who do not need
9171 or want it installed.</p>
9174 It is often a good idea to put text information files
9175 (<file>README</file>s, changelogs, and so forth) that come with
9176 the source package in <file>/usr/share/doc/<var>package</var></file>
9177 in the binary package. However, you don't need to install
9178 the instructions for building and installing the package, of
9182 Packages must not require the existence of any files in
9183 <file>/usr/share/doc/</file> in order to function
9185 The system administrator should be able to
9186 delete files in <file>/usr/share/doc/</file> without causing
9187 any programs to break.
9189 Any files that are referenced by programs but are also
9190 useful as stand alone documentation should be installed under
9191 <file>/usr/share/<var>package</var>/</file> with symbolic links from
9192 <file>/usr/share/doc/<var>package</var></file>.
9196 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9197 link to another directory in <file>/usr/share/doc</file> only if
9198 the two packages both come from the same source and the
9199 first package Depends on the second.<footnote>
9201 Please note that this does not override the section on
9202 changelog files below, so the file
9203 <file>/usr/share/doc/<var>package</var>/changelog.Debian.gz</file>
9204 must refer to the changelog for the current version of
9205 <var>package</var> in question. In practice, this means
9206 that the sources of the target and the destination of the
9207 symlink must be the same (same source package and
9214 Former Debian releases placed all additional documentation
9215 in <file>/usr/doc/<var>package</var></file>. This has been
9216 changed to <file>/usr/share/doc/<var>package</var></file>,
9217 and packages must not put documentation in the directory
9218 <file>/usr/doc/<var>package</var></file>. <footnote>
9219 At this phase of the transition, we no longer require a
9220 symbolic link in <file>/usr/doc/</file>. At a later point,
9221 policy shall change to make the symbolic links a bug.
9227 <heading>Preferred documentation formats</heading>
9230 The unification of Debian documentation is being carried out
9234 If your package comes with extensive documentation in a
9235 markup format that can be converted to various other formats
9236 you should if possible ship HTML versions in a binary
9237 package, in the directory
9238 <file>/usr/share/doc/<var>appropriate-package</var></file> or
9239 its subdirectories.<footnote>
9240 The rationale: The important thing here is that HTML
9241 docs should be available in <em>some</em> package, not
9242 necessarily in the main binary package.
9247 Other formats such as PostScript may be provided at the
9248 package maintainer's discretion.
9252 <sect id="copyrightfile">
9253 <heading>Copyright information</heading>
9256 Every package must be accompanied by a verbatim copy of its
9257 copyright information and distribution license in the file
9258 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
9259 file must neither be compressed nor be a symbolic link.
9263 In addition, the copyright file must say where the upstream
9264 sources (if any) were obtained. It should name the original
9265 authors of the package and the Debian maintainer(s) who were
9266 involved with its creation.
9270 Packages in the <em>contrib</em> or <em>non-free</em> archive
9271 areas should state in the copyright file that the package is not
9272 part of the Debian GNU/Linux distribution and briefly explain
9277 A copy of the file which will be installed in
9278 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9279 be in <file>debian/copyright</file> in the source package.
9283 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9284 link to another directory in <file>/usr/share/doc</file> only if
9285 the two packages both come from the same source and the
9286 first package Depends on the second. These rules are
9287 important because copyrights must be extractable by
9292 Packages distributed under the Apache license (version 2.0), the
9293 Artistic license, the GNU GPL (version 2 or 3), the GNU LGPL
9294 (versions 2, 2.1, or 3), and the GNU FDL (versions 1.2 or 1.3)
9295 should refer to the corresponding files
9296 under <file>/usr/share/common-licenses</file>,<footnote>
9299 <file>/usr/share/common-licenses/Apache-2.0</file>,
9300 <file>/usr/share/common-licenses/Artistic</file>,
9301 <file>/usr/share/common-licenses/GPL-2</file>,
9302 <file>/usr/share/common-licenses/GPL-3</file>,
9303 <file>/usr/share/common-licenses/LGPL-2</file>,
9304 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9305 <file>/usr/share/common-licenses/LGPL-3</file>,
9306 <file>/usr/share/common-licenses/GFDL-1.2</file>, and
9307 <file>/usr/share/common-licenses/GFDL-1.3</file>
9308 respectively. The University of California BSD license is
9309 also included in <package>base-files</package> as
9310 <file>/usr/share/common-licenses/BSD</file>, but given the
9311 brevity of this license, its specificity to code whose
9312 copyright is held by the Regents of the University of
9313 California, and the frequency of minor wording changes, its
9314 text should be included in the copyright file rather than
9315 referencing this file.
9317 </footnote> rather than quoting them in the copyright
9322 You should not use the copyright file as a general <file>README</file>
9323 file. If your package has such a file it should be
9324 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9325 <file>README.Debian</file> or some other appropriate place.</p>
9329 <heading>Examples</heading>
9332 Any examples (configurations, source files, whatever),
9333 should be installed in a directory
9334 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9335 files should not be referenced by any program: they're there
9336 for the benefit of the system administrator and users as
9337 documentation only. Architecture-specific example files
9338 should be installed in a directory
9339 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9341 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9342 latter directory itself may be a symbolic link to the
9347 If the purpose of a package is to provide examples, then the
9348 example files may be installed into
9349 <file>/usr/share/doc/<var>package</var></file>.
9353 <sect id="changelogs">
9354 <heading>Changelog files</heading>
9357 Packages that are not Debian-native must contain a
9358 compressed copy of the <file>debian/changelog</file> file from
9359 the Debian source tree in
9360 <file>/usr/share/doc/<var>package</var></file> with the name
9361 <file>changelog.Debian.gz</file>.
9365 If an upstream changelog is available, it should be accessible as
9366 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9367 plain text. If the upstream changelog is distributed in
9368 HTML, it should be made available in that form as
9369 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9370 and a plain text <file>changelog.gz</file> should be generated
9371 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9372 the upstream changelog files do not already conform to this
9373 naming convention, then this may be achieved either by
9374 renaming the files, or by adding a symbolic link, at the
9375 maintainer's discretion.<footnote>
9376 Rationale: People should not have to look in places for
9377 upstream changelogs merely because they are given
9378 different names or are distributed in HTML format.
9383 All of these files should be installed compressed using
9384 <tt>gzip -9</tt>, as they will become large with time even
9385 if they start out small.
9389 If the package has only one changelog which is used both as
9390 the Debian changelog and the upstream one because there is
9391 no separate upstream maintainer then that changelog should
9392 usually be installed as
9393 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9394 there is a separate upstream maintainer, but no upstream
9395 changelog, then the Debian changelog should still be called
9396 <file>changelog.Debian.gz</file>.
9400 For details about the format and contents of the Debian
9401 changelog file, please see <ref id="dpkgchangelog">.
9406 <appendix id="pkg-scope">
9407 <heading>Introduction and scope of these appendices</heading>
9410 These appendices are taken essentially verbatim from the
9411 now-deprecated Packaging Manual, version 3.2.1.0. They are
9412 the chapters which are likely to be of use to package
9413 maintainers and which have not already been included in the
9414 policy document itself. Most of these sections are very likely
9415 not relevant to policy; they should be treated as
9416 documentation for the packaging system. Please note that these
9417 appendices are included for convenience, and for historical
9418 reasons: they used to be part of policy package, and they have
9419 not yet been incorporated into dpkg documentation. However,
9420 they still have value, and hence they are presented here.
9424 They have not yet been checked to ensure that they are
9425 compatible with the contents of policy, and if there are any
9426 contradictions, the version in the main policy document takes
9427 precedence. The remaining chapters of the old Packaging
9428 Manual have also not been read in detail to ensure that there
9429 are not parts which have been left out. Both of these will be
9434 Certain parts of the Packaging manual were integrated into the
9435 Policy Manual proper, and removed from the appendices. Links
9436 have been placed from the old locations to the new ones.
9440 <prgn>dpkg</prgn> is a suite of programs for creating binary
9441 package files and installing and removing them on Unix
9443 <prgn>dpkg</prgn> is targeted primarily at Debian
9444 GNU/Linux, but may work on or be ported to other
9450 The binary packages are designed for the management of
9451 installed executable programs (usually compiled binaries) and
9452 their associated data, though source code examples and
9453 documentation are provided as part of some packages.</p>
9456 This manual describes the technical aspects of creating Debian
9457 binary packages (<file>.deb</file> files). It documents the
9458 behavior of the package management programs
9459 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9460 they interact with packages.</p>
9463 It also documents the interaction between
9464 <prgn>dselect</prgn>'s core and the access method scripts it
9465 uses to actually install the selected packages, and describes
9466 how to create a new access method.</p>
9469 This manual does not go into detail about the options and
9470 usage of the package building and installation tools. It
9471 should therefore be read in conjunction with those programs'
9476 The utility programs which are provided with <prgn>dpkg</prgn>
9477 for managing various system configuration and similar issues,
9478 such as <prgn>update-rc.d</prgn> and
9479 <prgn>install-info</prgn>, are not described in detail here -
9480 please see their man pages.
9484 It is assumed that the reader is reasonably familiar with the
9485 <prgn>dpkg</prgn> System Administrators' manual.
9486 Unfortunately this manual does not yet exist.
9490 The Debian version of the FSF's GNU hello program is provided
9491 as an example for people wishing to create Debian
9492 packages. The Debian <prgn>debmake</prgn> package is
9493 recommended as a very helpful tool in creating and maintaining
9494 Debian packages. However, while the tools and examples are
9495 helpful, they do not replace the need to read and follow the
9496 Policy and Programmer's Manual.</p>
9499 <appendix id="pkg-binarypkg">
9500 <heading>Binary packages (from old Packaging Manual)</heading>
9503 The binary package has two main sections. The first part
9504 consists of various control information files and scripts used
9505 by <prgn>dpkg</prgn> when installing and removing. See <ref
9506 id="pkg-controlarea">.
9510 The second part is an archive containing the files and
9511 directories to be installed.
9515 In the future binary packages may also contain other
9516 components, such as checksums and digital signatures. The
9517 format for the archive is described in full in the
9518 <file>deb(5)</file> man page.
9522 <sect id="pkg-bincreating"><heading>Creating package files -
9523 <prgn>dpkg-deb</prgn>
9527 All manipulation of binary package files is done by
9528 <prgn>dpkg-deb</prgn>; it's the only program that has
9529 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9530 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9531 will spot that the options requested are appropriate to
9532 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9537 In order to create a binary package you must make a
9538 directory tree which contains all the files and directories
9539 you want to have in the file system data part of the package.
9540 In Debian-format source packages this directory is usually
9541 <file>debian/tmp</file>, relative to the top of the package's
9546 They should have the locations (relative to the root of the
9547 directory tree you're constructing) ownerships and
9548 permissions which you want them to have on the system when
9553 With current versions of <prgn>dpkg</prgn> the uid/username
9554 and gid/groupname mappings for the users and groups being
9555 used should be the same on the system where the package is
9556 built and the one where it is installed.
9560 You need to add one special directory to the root of the
9561 miniature file system tree you're creating:
9562 <prgn>DEBIAN</prgn>. It should contain the control
9563 information files, notably the binary package control file
9564 (see <ref id="pkg-controlfile">).
9568 The <prgn>DEBIAN</prgn> directory will not appear in the
9569 file system archive of the package, and so won't be installed
9570 by <prgn>dpkg</prgn> when the package is installed.
9574 When you've prepared the package, you should invoke:
9576 dpkg --build <var>directory</var>
9581 This will build the package in
9582 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9583 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9584 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9589 See the man page <manref name="dpkg-deb" section="8"> for details of how
9590 to examine the contents of this newly-created file. You may find the
9591 output of following commands enlightening:
9593 dpkg-deb --info <var>filename</var>.deb
9594 dpkg-deb --contents <var>filename</var>.deb
9595 dpkg --contents <var>filename</var>.deb
9597 To view the copyright file for a package you could use this command:
9599 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
9604 <sect id="pkg-controlarea">
9605 <heading>Package control information files</heading>
9608 The control information portion of a binary package is a
9609 collection of files with names known to <prgn>dpkg</prgn>.
9610 It will treat the contents of these files specially - some
9611 of them contain information used by <prgn>dpkg</prgn> when
9612 installing or removing the package; others are scripts which
9613 the package maintainer wants <prgn>dpkg</prgn> to run.
9617 It is possible to put other files in the package control
9618 area, but this is not generally a good idea (though they
9619 will largely be ignored).
9623 Here is a brief list of the control info files supported by
9624 <prgn>dpkg</prgn> and a summary of what they're used for.
9629 <tag><tt>control</tt>
9632 This is the key description file used by
9633 <prgn>dpkg</prgn>. It specifies the package's name
9634 and version, gives its description for the user,
9635 states its relationships with other packages, and so
9636 forth. See <ref id="sourcecontrolfiles"> and
9637 <ref id="binarycontrolfiles">.
9641 It is usually generated automatically from information
9642 in the source package by the
9643 <prgn>dpkg-gencontrol</prgn> program, and with
9644 assistance from <prgn>dpkg-shlibdeps</prgn>.
9645 See <ref id="pkg-sourcetools">.
9649 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9654 These are executable files (usually scripts) which
9655 <prgn>dpkg</prgn> runs during installation, upgrade
9656 and removal of packages. They allow the package to
9657 deal with matters which are particular to that package
9658 or require more complicated processing than that
9659 provided by <prgn>dpkg</prgn>. Details of when and
9660 how they are called are in <ref id="maintainerscripts">.
9664 It is very important to make these scripts idempotent.
9665 See <ref id="idempotency">.
9669 The maintainer scripts are not guaranteed to run with a
9670 controlling terminal and may not be able to interact with
9671 the user. See <ref id="controllingterminal">.
9675 <tag><tt>conffiles</tt>
9678 This file contains a list of configuration files which
9679 are to be handled automatically by <prgn>dpkg</prgn>
9680 (see <ref id="pkg-conffiles">). Note that not necessarily
9681 every configuration file should be listed here.
9684 <tag><tt>shlibs</tt>
9687 This file contains a list of the shared libraries
9688 supplied by the package, with dependency details for
9689 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9690 when it determines what dependencies are required in a
9691 package control file. The <tt>shlibs</tt> file format
9692 is described on <ref id="shlibs">.
9697 <sect id="pkg-controlfile">
9698 <heading>The main control information file: <tt>control</tt></heading>
9701 The most important control information file used by
9702 <prgn>dpkg</prgn> when it installs a package is
9703 <tt>control</tt>. It contains all the package's "vital
9708 The binary package control files of packages built from
9709 Debian sources are made by a special tool,
9710 <prgn>dpkg-gencontrol</prgn>, which reads
9711 <file>debian/control</file> and <file>debian/changelog</file> to
9712 find the information it needs. See <ref id="pkg-sourcepkg"> for
9717 The fields in binary package control files are listed in
9718 <ref id="binarycontrolfiles">.
9722 A description of the syntax of control files and the purpose
9723 of the fields is available in <ref id="controlfields">.
9728 <heading>Time Stamps</heading>
9731 See <ref id="timestamps">.
9736 <appendix id="pkg-sourcepkg">
9737 <heading>Source packages (from old Packaging Manual) </heading>
9740 The Debian binary packages in the distribution are generated
9741 from Debian sources, which are in a special format to assist
9742 the easy and automatic building of binaries.
9745 <sect id="pkg-sourcetools">
9746 <heading>Tools for processing source packages</heading>
9749 Various tools are provided for manipulating source packages;
9750 they pack and unpack sources and help build of binary
9751 packages and help manage the distribution of new versions.
9755 They are introduced and typical uses described here; see
9756 <manref name="dpkg-source" section="1"> for full
9757 documentation about their arguments and operation.
9761 For examples of how to construct a Debian source package,
9762 and how to use those utilities that are used by Debian
9763 source packages, please see the <prgn>hello</prgn> example
9767 <sect1 id="pkg-dpkg-source">
9769 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
9774 This program is frequently used by hand, and is also
9775 called from package-independent automated building scripts
9776 such as <prgn>dpkg-buildpackage</prgn>.
9780 To unpack a package it is typically invoked with
9782 dpkg-source -x <var>.../path/to/filename</var>.dsc
9787 with the <file><var>filename</var>.tar.gz</file> and
9788 <file><var>filename</var>.diff.gz</file> (if applicable) in
9789 the same directory. It unpacks into
9790 <file><var>package</var>-<var>version</var></file>, and if
9792 <file><var>package</var>-<var>version</var>.orig</file>, in
9793 the current directory.
9797 To create a packed source archive it is typically invoked:
9799 dpkg-source -b <var>package</var>-<var>version</var>
9804 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
9805 <file>.diff.gz</file> (if appropriate) in the current
9806 directory. <prgn>dpkg-source</prgn> does not clean the
9807 source tree first - this must be done separately if it is
9812 See also <ref id="pkg-sourcearchives">.</p>
9816 <sect1 id="pkg-dpkg-buildpackage">
9818 <prgn>dpkg-buildpackage</prgn> - overall package-building
9823 <prgn>dpkg-buildpackage</prgn> is a script which invokes
9824 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
9825 targets <tt>clean</tt>, <tt>build</tt> and
9826 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
9827 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
9828 source and binary package upload.
9832 It is usually invoked by hand from the top level of the
9833 built or unbuilt source directory. It may be invoked with
9834 no arguments; useful arguments include:
9835 <taglist compact="compact">
9836 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
9839 Do not sign the <tt>.changes</tt> file or the
9840 source package <tt>.dsc</tt> file, respectively.</p>
9842 <tag><tt>-p<var>sign-command</var></tt></tag>
9845 Invoke <var>sign-command</var> instead of finding
9846 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
9847 <var>sign-command</var> must behave just like
9848 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9850 <tag><tt>-r<var>root-command</var></tt></tag>
9853 When root privilege is required, invoke the command
9854 <var>root-command</var>. <var>root-command</var>
9855 should invoke its first argument as a command, from
9856 the <prgn>PATH</prgn> if necessary, and pass its
9857 second and subsequent arguments to the command it
9858 calls. If no <var>root-command</var> is supplied
9859 then <var>dpkg-buildpackage</var> will take no
9860 special action to gain root privilege, so that for
9861 most packages it will have to be invoked as root to
9864 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9867 Two types of binary-only build and upload - see
9868 <manref name="dpkg-source" section="1">.
9875 <sect1 id="pkg-dpkg-gencontrol">
9877 <prgn>dpkg-gencontrol</prgn> - generates binary package
9882 This program is usually called from <file>debian/rules</file>
9883 (see <ref id="pkg-sourcetree">) in the top level of the source
9888 This is usually done just before the files and directories in the
9889 temporary directory tree where the package is being built have their
9890 permissions and ownerships set and the package is constructed using
9891 <prgn>dpkg-deb/</prgn>
9893 This is so that the control file which is produced has
9894 the right permissions
9899 <prgn>dpkg-gencontrol</prgn> must be called after all the
9900 files which are to go into the package have been placed in
9901 the temporary build directory, so that its calculation of
9902 the installed size of a package is correct.
9906 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9907 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9908 variable substitutions created by
9909 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9914 For a package which generates only one binary package, and
9915 which builds it in <file>debian/tmp</file> relative to the top
9916 of the source package, it is usually sufficient to call
9917 <prgn>dpkg-gencontrol</prgn>.
9921 Sources which build several binaries will typically need
9924 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9925 </example> The <tt>-P</tt> tells
9926 <prgn>dpkg-gencontrol</prgn> that the package is being
9927 built in a non-default directory, and the <tt>-p</tt>
9928 tells it which package's control file should be generated.
9932 <prgn>dpkg-gencontrol</prgn> also adds information to the
9933 list of files in <file>debian/files</file>, for the benefit of
9934 (for example) a future invocation of
9935 <prgn>dpkg-genchanges</prgn>.</p>
9938 <sect1 id="pkg-dpkg-shlibdeps">
9940 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9945 This program is usually called from <file>debian/rules</file>
9946 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9947 id="pkg-sourcetree">), in the top level of the source tree.
9951 Its arguments are executables and shared libraries
9954 They may be specified either in the locations in the
9955 source tree where they are created or in the locations
9956 in the temporary build tree where they are installed
9957 prior to binary package creation.
9959 </footnote> for which shared library dependencies should
9960 be included in the binary package's control file.
9964 If some of the found shared libraries should only
9965 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9966 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9967 by using the <tt>-d<var>dependency-field</var></tt> option
9968 before those executable(s). (Each <tt>-d</tt> option
9969 takes effect until the next <tt>-d</tt>.)
9973 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9974 output control file to be modified. Instead by default it
9975 adds to the <file>debian/substvars</file> file variable
9976 settings like <tt>shlibs:Depends</tt>. These variable
9977 settings must be referenced in dependency fields in the
9978 appropriate per-binary-package sections of the source
9983 For example, a package that generates an essential part
9984 which requires dependencies, and optional parts that
9985 which only require a recommendation, would separate those
9986 two sets of dependencies into two different fields.<footnote>
9987 At the time of writing, an example for this was the
9988 <package/xmms/ package, with Depends used for the xmms
9989 executable, Recommends for the plug-ins and Suggests for
9990 even more optional features provided by unzip.
9992 It can say in its <file>debian/rules</file>:
9994 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9995 -dRecommends <var>optionalpart anotheroptionalpart</var>
9997 and then in its main control file <file>debian/control</file>:
10000 Depends: ${shlibs:Depends}
10001 Recommends: ${shlibs:Recommends}
10007 Sources which produce several binary packages with
10008 different shared library dependency requirements can use
10009 the <tt>-p<var>varnameprefix</var></tt> option to override
10010 the default <tt>shlibs:</tt> prefix (one invocation of
10011 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
10012 They can thus produce several sets of dependency
10013 variables, each of the form
10014 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
10015 which can be referred to in the appropriate parts of the
10016 binary package control files.
10021 <sect1 id="pkg-dpkg-distaddfile">
10023 <prgn>dpkg-distaddfile</prgn> - adds a file to
10024 <file>debian/files</file>
10028 Some packages' uploads need to include files other than
10029 the source and binary package files.
10033 <prgn>dpkg-distaddfile</prgn> adds a file to the
10034 <file>debian/files</file> file so that it will be included in
10035 the <file>.changes</file> file when
10036 <prgn>dpkg-genchanges</prgn> is run.
10040 It is usually invoked from the <tt>binary</tt> target of
10041 <file>debian/rules</file>:
10043 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
10045 The <var>filename</var> is relative to the directory where
10046 <prgn>dpkg-genchanges</prgn> will expect to find it - this
10047 is usually the directory above the top level of the source
10048 tree. The <file>debian/rules</file> target should put the
10049 file there just before or just after calling
10050 <prgn>dpkg-distaddfile</prgn>.
10054 The <var>section</var> and <var>priority</var> are passed
10055 unchanged into the resulting <file>.changes</file> file.
10060 <sect1 id="pkg-dpkg-genchanges">
10062 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
10063 upload control file
10067 This program is usually called by package-independent
10068 automatic building scripts such as
10069 <prgn>dpkg-buildpackage</prgn>, but it may also be called
10074 It is usually called in the top level of a built source
10075 tree, and when invoked with no arguments will print out a
10076 straightforward <file>.changes</file> file based on the
10077 information in the source package's changelog and control
10078 file and the binary and source packages which should have
10084 <sect1 id="pkg-dpkg-parsechangelog">
10086 <prgn>dpkg-parsechangelog</prgn> - produces parsed
10087 representation of a changelog
10091 This program is used internally by
10092 <prgn>dpkg-source</prgn> et al. It may also occasionally
10093 be useful in <file>debian/rules</file> and elsewhere. It
10094 parses a changelog, <file>debian/changelog</file> by default,
10095 and prints a control-file format representation of the
10096 information in it to standard output.
10100 <sect1 id="pkg-dpkg-architecture">
10102 <prgn>dpkg-architecture</prgn> - information about the build and
10107 This program can be used manually, but is also invoked by
10108 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
10109 environment or make variables which specify the build and host
10110 architecture for the package building process.
10115 <sect id="pkg-sourcetree">
10116 <heading>The Debianised source tree</heading>
10119 The source archive scheme described later is intended to
10120 allow a Debianised source tree with some associated control
10121 information to be reproduced and transported easily. The
10122 Debianised source tree is a version of the original program
10123 with certain files added for the benefit of the
10124 Debianisation process, and with any other changes required
10125 made to the rest of the source code and installation
10130 The extra files created for Debian are in the subdirectory
10131 <file>debian</file> of the top level of the Debianised source
10132 tree. They are described below.
10135 <sect1 id="pkg-debianrules">
10136 <heading><file>debian/rules</file> - the main building script</heading>
10139 See <ref id="debianrules">.
10143 <sect1 id="pkg-srcsubstvars">
10144 <heading><file>debian/substvars</file> and variable substitutions</heading>
10147 See <ref id="substvars">.
10153 <heading><file>debian/files</file></heading>
10156 See <ref id="debianfiles">.
10160 <sect1><heading><file>debian/tmp</file>
10164 This is the canonical temporary location for the
10165 construction of binary packages by the <tt>binary</tt>
10166 target. The directory <file>tmp</file> serves as the root of
10167 the file system tree as it is being constructed (for
10168 example, by using the package's upstream makefiles install
10169 targets and redirecting the output there), and it also
10170 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10171 id="pkg-bincreating">.
10175 If several binary packages are generated from the same
10176 source tree it is usual to use several
10177 <file>debian/tmp<var>something</var></file> directories, for
10178 example <file>tmp-a</file> or <file>tmp-doc</file>.
10182 Whatever <file>tmp</file> directories are created and used by
10183 <tt>binary</tt> must of course be removed by the
10184 <tt>clean</tt> target.</p></sect1>
10188 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10192 As it exists on the FTP site, a Debian source package
10193 consists of three related files. You must have the right
10194 versions of all three to be able to use them.
10199 <tag>Debian source control file - <tt>.dsc</tt></tag>
10201 This file is a control file used by <prgn>dpkg-source</prgn>
10202 to extract a source package.
10203 See <ref id="debiansourcecontrolfiles">.
10207 Original source archive -
10209 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10215 This is a compressed (with <tt>gzip -9</tt>)
10216 <prgn>tar</prgn> file containing the source code from
10217 the upstream authors of the program.
10222 Debianisation diff -
10224 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10230 This is a unified context diff (<tt>diff -u</tt>)
10231 giving the changes which are required to turn the
10232 original source into the Debian source. These changes
10233 may only include editing and creating plain files.
10234 The permissions of files, the targets of symbolic
10235 links and the characteristics of special files or
10236 pipes may not be changed and no files may be removed
10241 All the directories in the diff must exist, except the
10242 <file>debian</file> subdirectory of the top of the source
10243 tree, which will be created by
10244 <prgn>dpkg-source</prgn> if necessary when unpacking.
10248 The <prgn>dpkg-source</prgn> program will
10249 automatically make the <file>debian/rules</file> file
10250 executable (see below).</p></item>
10255 If there is no original source code - for example, if the
10256 package is specially prepared for Debian or the Debian
10257 maintainer is the same as the upstream maintainer - the
10258 format is slightly different: then there is no diff, and the
10260 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10261 and preferably contains a directory named
10262 <file><var>package</var>-<var>version</var></file>.
10267 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10270 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10271 Debian source package. However, if it is not available it
10272 is possible to unpack a Debian source archive as follows:
10273 <enumlist compact="compact">
10276 Untar the tarfile, which will create a <file>.orig</file>
10280 <p>Rename the <file>.orig</file> directory to
10281 <file><var>package</var>-<var>version</var></file>.</p>
10285 Create the subdirectory <file>debian</file> at the top of
10286 the source tree.</p>
10288 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10290 <item><p>Untar the tarfile again if you want a copy of the original
10291 source code alongside the Debianised version.</p>
10296 It is not possible to generate a valid Debian source archive
10297 without using <prgn>dpkg-source</prgn>. In particular,
10298 attempting to use <prgn>diff</prgn> directly to generate the
10299 <file>.diff.gz</file> file will not work.
10303 <heading>Restrictions on objects in source packages</heading>
10306 The source package may not contain any hard links
10308 This is not currently detected when building source
10309 packages, but only when extracting
10313 Hard links may be permitted at some point in the
10314 future, but would require a fair amount of
10316 </footnote>, device special files, sockets or setuid or
10319 Setgid directories are allowed.
10324 The source packaging tools manage the changes between the
10325 original and Debianised source using <prgn>diff</prgn> and
10326 <prgn>patch</prgn>. Turning the original source tree as
10327 included in the <file>.orig.tar.gz</file> into the debianised
10328 source must not involve any changes which cannot be
10329 handled by these tools. Problematic changes which cause
10330 <prgn>dpkg-source</prgn> to halt with an error when
10331 building the source package are:
10332 <list compact="compact">
10333 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10335 <item><p>Changing the targets of symbolic links.</p>
10337 <item><p>Creating directories, other than <file>debian</file>.</p>
10339 <item><p>Changes to the contents of binary files.</p></item>
10340 </list> Changes which cause <prgn>dpkg-source</prgn> to
10341 print a warning but continue anyway are:
10342 <list compact="compact">
10345 Removing files, directories or symlinks.
10347 Renaming a file is not treated specially - it is
10348 seen as the removal of the old file (which
10349 generates a warning, but is otherwise ignored),
10350 and the creation of the new one.
10356 Changed text files which are missing the usual final
10357 newline (either in the original or the modified
10362 Changes which are not represented, but which are not detected by
10363 <prgn>dpkg-source</prgn>, are:
10364 <list compact="compact">
10365 <item><p>Changing the permissions of files (other than
10366 <file>debian/rules</file>) and directories.</p></item>
10371 The <file>debian</file> directory and <file>debian/rules</file>
10372 are handled specially by <prgn>dpkg-source</prgn> - before
10373 applying the changes it will create the <file>debian</file>
10374 directory, and afterwards it will make
10375 <file>debian/rules</file> world-executable.
10381 <appendix id="pkg-controlfields">
10382 <heading>Control files and their fields (from old Packaging Manual)</heading>
10385 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10386 data in a common format, known as control files. Binary and
10387 source packages have control data as do the <file>.changes</file>
10388 files which control the installation of uploaded files, and
10389 <prgn>dpkg</prgn>'s internal databases are in a similar
10394 <heading>Syntax of control files</heading>
10397 See <ref id="controlsyntax">.
10401 It is important to note that there are several fields which
10402 are optional as far as <prgn>dpkg</prgn> and the related
10403 tools are concerned, but which must appear in every Debian
10404 package, or whose omission may cause problems.
10409 <heading>List of fields</heading>
10412 See <ref id="controlfieldslist">.
10416 This section now contains only the fields that didn't belong
10417 to the Policy manual.
10420 <sect1 id="pkg-f-Filename">
10421 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10424 These fields in <tt>Packages</tt> files give the
10425 filename(s) of (the parts of) a package in the
10426 distribution directories, relative to the root of the
10427 Debian hierarchy. If the package has been split into
10428 several parts the parts are all listed in order, separated
10433 <sect1 id="pkg-f-Size">
10434 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10437 These fields in <file>Packages</file> files give the size (in
10438 bytes, expressed in decimal) and MD5 checksum of the
10439 file(s) which make(s) up a binary package in the
10440 distribution. If the package is split into several parts
10441 the values for the parts are listed in order, separated by
10446 <sect1 id="pkg-f-Status">
10447 <heading><tt>Status</tt></heading>
10450 This field in <prgn>dpkg</prgn>'s status file records
10451 whether the user wants a package installed, removed or
10452 left alone, whether it is broken (requiring
10453 re-installation) or not and what its current state on the
10454 system is. Each of these pieces of information is a
10459 <sect1 id="pkg-f-Config-Version">
10460 <heading><tt>Config-Version</tt></heading>
10463 If a package is not installed or not configured, this
10464 field in <prgn>dpkg</prgn>'s status file records the last
10465 version of the package which was successfully
10470 <sect1 id="pkg-f-Conffiles">
10471 <heading><tt>Conffiles</tt></heading>
10474 This field in <prgn>dpkg</prgn>'s status file contains
10475 information about the automatically-managed configuration
10476 files held by a package. This field should <em>not</em>
10477 appear anywhere in a package!
10482 <heading>Obsolete fields</heading>
10485 These are still recognized by <prgn>dpkg</prgn> but should
10486 not appear anywhere any more.
10488 <taglist compact="compact">
10490 <tag><tt>Revision</tt></tag>
10491 <tag><tt>Package-Revision</tt></tag>
10492 <tag><tt>Package_Revision</tt></tag>
10494 The Debian revision part of the package version was
10495 at one point in a separate control file field. This
10496 field went through several names.
10499 <tag><tt>Recommended</tt></tag>
10500 <item>Old name for <tt>Recommends</tt>.</item>
10502 <tag><tt>Optional</tt></tag>
10503 <item>Old name for <tt>Suggests</tt>.</item>
10505 <tag><tt>Class</tt></tag>
10506 <item>Old name for <tt>Priority</tt>.</item>
10515 <appendix id="pkg-conffiles">
10516 <heading>Configuration file handling (from old Packaging Manual)</heading>
10519 <prgn>dpkg</prgn> can do a certain amount of automatic
10520 handling of package configuration files.
10524 Whether this mechanism is appropriate depends on a number of
10525 factors, but basically there are two approaches to any
10526 particular configuration file.
10530 The easy method is to ship a best-effort configuration in the
10531 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10532 handle updates. If the user is unlikely to want to edit the
10533 file, but you need them to be able to without losing their
10534 changes, and a new package with a changed version of the file
10535 is only released infrequently, this is a good approach.
10539 The hard method is to build the configuration file from
10540 scratch in the <prgn>postinst</prgn> script, and to take the
10541 responsibility for fixing any mistakes made in earlier
10542 versions of the package automatically. This will be
10543 appropriate if the file is likely to need to be different on
10547 <sect><heading>Automatic handling of configuration files by
10552 A package may contain a control area file called
10553 <tt>conffiles</tt>. This file should be a list of filenames
10554 of configuration files needing automatic handling, separated
10555 by newlines. The filenames should be absolute pathnames,
10556 and the files referred to should actually exist in the
10561 When a package is upgraded <prgn>dpkg</prgn> will process
10562 the configuration files during the configuration stage,
10563 shortly before it runs the package's <prgn>postinst</prgn>
10568 For each file it checks to see whether the version of the
10569 file included in the package is the same as the one that was
10570 included in the last version of the package (the one that is
10571 being upgraded from); it also compares the version currently
10572 installed on the system with the one shipped with the last
10577 If neither the user nor the package maintainer has changed
10578 the file, it is left alone. If one or the other has changed
10579 their version, then the changed version is preferred - i.e.,
10580 if the user edits their file, but the package maintainer
10581 doesn't ship a different version, the user's changes will
10582 stay, silently, but if the maintainer ships a new version
10583 and the user hasn't edited it the new version will be
10584 installed (with an informative message). If both have
10585 changed their version the user is prompted about the problem
10586 and must resolve the differences themselves.
10590 The comparisons are done by calculating the MD5 message
10591 digests of the files, and storing the MD5 of the file as it
10592 was included in the most recent version of the package.
10596 When a package is installed for the first time
10597 <prgn>dpkg</prgn> will install the file that comes with it,
10598 unless that would mean overwriting a file already on the
10603 However, note that <prgn>dpkg</prgn> will <em>not</em>
10604 replace a conffile that was removed by the user (or by a
10605 script). This is necessary because with some programs a
10606 missing file produces an effect hard or impossible to
10607 achieve in another way, so that a missing file needs to be
10608 kept that way if the user did it.
10612 Note that a package should <em>not</em> modify a
10613 <prgn>dpkg</prgn>-handled conffile in its maintainer
10614 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10615 the user confusing and possibly dangerous options for
10616 conffile update when the package is upgraded.</p>
10619 <sect><heading>Fully-featured maintainer script configuration
10624 For files which contain site-specific information such as
10625 the hostname and networking details and so forth, it is
10626 better to create the file in the package's
10627 <prgn>postinst</prgn> script.
10631 This will typically involve examining the state of the rest
10632 of the system to determine values and other information, and
10633 may involve prompting the user for some information which
10634 can't be obtained some other way.
10638 When using this method there are a couple of important
10639 issues which should be considered:
10643 If you discover a bug in the program which generates the
10644 configuration file, or if the format of the file changes
10645 from one version to the next, you will have to arrange for
10646 the postinst script to do something sensible - usually this
10647 will mean editing the installed configuration file to remove
10648 the problem or change the syntax. You will have to do this
10649 very carefully, since the user may have changed the file,
10650 perhaps to fix the very problem that your script is trying
10651 to deal with - you will have to detect these situations and
10652 deal with them correctly.
10656 If you do go down this route it's probably a good idea to
10657 make the program that generates the configuration file(s) a
10658 separate program in <file>/usr/sbin</file>, by convention called
10659 <file><var>package</var>config</file> and then run that if
10660 appropriate from the post-installation script. The
10661 <tt><var>package</var>config</tt> program should not
10662 unquestioningly overwrite an existing configuration - if its
10663 mode of operation is geared towards setting up a package for
10664 the first time (rather than any arbitrary reconfiguration
10665 later) you should have it check whether the configuration
10666 already exists, and require a <tt>--force</tt> flag to
10667 overwrite it.</p></sect>
10670 <appendix id="pkg-alternatives"><heading>Alternative versions of
10671 an interface - <prgn>update-alternatives</prgn> (from old
10676 When several packages all provide different versions of the
10677 same program or file it is useful to have the system select a
10678 default, but to allow the system administrator to change it
10679 and have their decisions respected.
10683 For example, there are several versions of the <prgn>vi</prgn>
10684 editor, and there is no reason to prevent all of them from
10685 being installed at once, each under their own name
10686 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10687 Nevertheless it is desirable to have the name <tt>vi</tt>
10688 refer to something, at least by default.
10692 If all the packages involved cooperate, this can be done with
10693 <prgn>update-alternatives</prgn>.
10697 Each package provides its own version under its own name, and
10698 calls <prgn>update-alternatives</prgn> in its postinst to
10699 register its version (and again in its prerm to deregister
10704 See the man page <manref name="update-alternatives"
10705 section="8"> for details.
10709 If <prgn>update-alternatives</prgn> does not seem appropriate
10710 you may wish to consider using diversions instead.</p>
10713 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10714 package's version of a file (from old Packaging Manual)
10718 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10719 when it reinstalls the package it belongs to, and to have it
10720 put the file from the package somewhere else instead.
10724 This can be used locally to override a package's version of a
10725 file, or by one package to override another's version (or
10726 provide a wrapper for it).
10730 Before deciding to use a diversion, read <ref
10731 id="pkg-alternatives"> to see if you really want a diversion
10732 rather than several alternative versions of a program.
10736 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10737 and updated by a special program <prgn>dpkg-divert</prgn>.
10738 Please see <manref name="dpkg-divert" section="8"> for full
10739 details of its operation.
10743 When a package wishes to divert a file from another, it should
10744 call <prgn>dpkg-divert</prgn> in its preinst to add the
10745 diversion and rename the existing file. For example,
10746 supposing that a <prgn>smailwrapper</prgn> package wishes to
10747 install a wrapper around <file>/usr/sbin/smail</file>:
10749 dpkg-divert --package smailwrapper --add --rename \
10750 --divert /usr/sbin/smail.real /usr/sbin/smail
10751 </example> The <tt>--package smailwrapper</tt> ensures that
10752 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
10753 can bypass the diversion and get installed as the true version.
10754 It's safe to add the diversion unconditionally on upgrades since
10755 it will be left unchanged if it already exists, but
10756 <prgn>dpkg-divert</prgn> will display a message. To suppress that
10757 message, make the command conditional on the version from which
10758 the package is being upgraded:
10760 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
10761 dpkg-divert --package smailwrapper --add --rename \
10762 --divert /usr/sbin/smail.real /usr/sbin/smail
10764 </example> where <tt>1.0-2</tt> is the version at which the
10765 diversion was first added to the package. Running the command
10766 during abort-upgrade is pointless but harmless.
10770 The postrm has to do the reverse:
10772 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
10773 dpkg-divert --package smailwrapper --remove --rename \
10774 --divert /usr/sbin/smail.real /usr/sbin/smail
10776 </example> If the diversion was added at a particular version, the
10777 postrm should also handle the failure case of upgrading from an
10778 older version (unless the older version is so old that direct
10779 upgrades are no longer supported):
10781 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
10782 dpkg-divert --package smailwrapper --remove --rename \
10783 --divert /usr/sbin/smail.real /usr/sbin/smail
10785 </example> where <tt>1.02-2</tt> is the version at which the
10786 diversion was first added to the package. The postrm should not
10787 remove the diversion on upgrades both because there's no reason to
10788 remove the diversion only to immediately re-add it and since the
10789 postrm of the old package is run after unpacking so the removal of
10790 the diversion will fail.
10794 Do not attempt to divert a file which is vitally important for
10795 the system's operation - when using <prgn>dpkg-divert</prgn>
10796 there is a time, after it has been diverted but before
10797 <prgn>dpkg</prgn> has installed the new version, when the file
10798 does not exist.</p>
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