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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 should 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
2698 names and email addresses should be listed here. The
2699 format is the same as that of the Maintainer tag, and
2700 multiple entries should be comma separated. Currently,
2701 this field is restricted to a single line of data. This
2702 is an optional field.
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 changed the
2718 said package. Usually the name of the maintainer.
2719 All the rules for the Maintainer field apply here, too.
2723 <sect1 id="f-Section">
2724 <heading><tt>Section</tt></heading>
2727 This field specifies an application area into which the package
2728 has been classified. See <ref id="subsections">.
2732 When it appears in the <file>debian/control</file> file,
2733 it gives the value for the subfield of the same name in
2734 the <tt>Files</tt> field of the <file>.changes</file> file.
2735 It also gives the default for the same field in the binary
2740 <sect1 id="f-Priority">
2741 <heading><tt>Priority</tt></heading>
2744 This field represents how important it is that the user
2745 have the package installed. See <ref id="priorities">.
2749 When it appears in the <file>debian/control</file> file,
2750 it gives the value for the subfield of the same name in
2751 the <tt>Files</tt> field of the <file>.changes</file> file.
2752 It also gives the default for the same field in the binary
2757 <sect1 id="f-Package">
2758 <heading><tt>Package</tt></heading>
2761 The name of the binary package.
2765 Binary package names must follow the same syntax and
2766 restrictions as source package names. See <ref id="f-Source">
2771 <sect1 id="f-Architecture">
2772 <heading><tt>Architecture</tt></heading>
2775 Depending on context and the control file used, the
2776 <tt>Architecture</tt> field can include the following sets of
2780 A unique single word identifying a Debian machine
2781 architecture as described in <ref id="arch-spec">.
2784 An architecture wildcard identifying a set of Debian
2785 machine architectures, see <ref id="arch-wildcard-spec">.
2786 <tt>any</tt> matches all Debian machine architectures
2787 and is the most frequently used.
2790 <tt>all</tt>, which indicates an
2791 architecture-independent package.
2794 <tt>source</tt>, which indicates a source package.
2800 In the main <file>debian/control</file> file in the source
2801 package, this field may contain the special
2802 value <tt>all</tt>, the special architecture
2803 wildcard <tt>any</tt>, or a list of specific and wildcard
2804 architectures separated by spaces. If <tt>all</tt>
2805 or <tt>any</tt> appears, that value must be the entire
2806 contents of the field. Most packages will use
2807 either <tt>all</tt> or <tt>any</tt>.
2811 Specifying a specific list of architectures indicates that the
2812 source will build an architecture-dependent package only on
2813 architectures included in the list. Specifying a list of
2814 architecture wildcards indicates that the source will build an
2815 architecture-dependent package on only those architectures
2816 that match any of the specified architecture wildcards.
2817 Specifying a list of architectures or architecture wildcards
2818 other than <tt>any</tt> is for the minority of cases where a
2819 program is not portable or is not useful on some
2820 architectures. Where possible, the program should be made
2825 In the source package control file <file>.dsc</file>, this
2826 field may contain either the architecture
2827 wildcard <tt>any</tt> or a list of architectures and
2828 architecture wildcards separated by spaces. If a list is
2829 given, it may include (or consist solely of) the special
2830 value <tt>all</tt>. In other words, in <file>.dsc</file>
2831 files unlike the <file>debian/control</file>, <tt>all</tt> may
2832 occur in combination with specific architectures.
2833 The <tt>Architecture</tt> field in the source package control
2834 file <file>.dsc</file> is generally constructed from
2835 the <tt>Architecture</tt> fields in
2836 the <file>debian/control</file> in the source package.
2840 Specifying <tt>any</tt> indicates that the source package
2841 isn't dependent on any particular architecture and should
2842 compile fine on any one. The produced binary package(s)
2843 will either be specific to whatever the current build
2844 architecture is or will be architecture-independent.
2848 Specifying only <tt>all</tt> indicates that the source package
2849 will only build architecture-independent packages. If this is
2850 the case, <tt>all</tt> must be used rather than <tt>any</tt>;
2851 <tt>any</tt> implies that the source package will build at
2852 least one architecture-dependent package.
2856 Specifying a list of architectures or architecture wildcards
2857 indicates that the source will build an architecture-dependent
2858 package, and will only work correctly on the listed or
2859 matching architectures. If the source package also builds at
2860 least one architecture-independent package, <tt>all</tt> will
2861 also be included in the list.
2865 In a <file>.changes</file> file, the <tt>Architecture</tt>
2866 field lists the architecture(s) of the package(s) currently
2867 being uploaded. This will be a list; if the source for the
2868 package is also being uploaded, the special
2869 entry <tt>source</tt> is also present. <tt>all</tt> will be
2870 present if any architecture-independent packages are being
2871 uploaded. Architecture wildcards such as <tt>any</tt> must
2872 never occur in the <tt>Architecture</tt> field in
2873 the <file>.changes</file> file.
2877 See <ref id="debianrules"> for information on how to get
2878 the architecture for the build process.
2882 <sect1 id="f-Essential">
2883 <heading><tt>Essential</tt></heading>
2886 This is a boolean field which may occur only in the
2887 control file of a binary package or in a per-package fields
2888 paragraph of a main source control data file.
2892 If set to <tt>yes</tt> then the package management system
2893 will refuse to remove the package (upgrading and replacing
2894 it is still possible). The other possible value is <tt>no</tt>,
2895 which is the same as not having the field at all.
2900 <heading>Package interrelationship fields:
2901 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2902 <tt>Recommends</tt>, <tt>Suggests</tt>,
2903 <tt>Breaks</tt>, <tt>Conflicts</tt>,
2904 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2908 These fields describe the package's relationships with
2909 other packages. Their syntax and semantics are described
2910 in <ref id="relationships">.</p>
2913 <sect1 id="f-Standards-Version">
2914 <heading><tt>Standards-Version</tt></heading>
2917 The most recent version of the standards (the policy
2918 manual and associated texts) with which the package
2923 The version number has four components: major and minor
2924 version number and major and minor patch level. When the
2925 standards change in a way that requires every package to
2926 change the major number will be changed. Significant
2927 changes that will require work in many packages will be
2928 signaled by a change to the minor number. The major patch
2929 level will be changed for any change to the meaning of the
2930 standards, however small; the minor patch level will be
2931 changed when only cosmetic, typographical or other edits
2932 are made which neither change the meaning of the document
2933 nor affect the contents of packages.
2937 Thus only the first three components of the policy version
2938 are significant in the <em>Standards-Version</em> control
2939 field, and so either these three components or all four
2940 components may be specified.<footnote>
2941 In the past, people specified the full version number
2942 in the Standards-Version field, for example "2.3.0.0".
2943 Since minor patch-level changes don't introduce new
2944 policy, it was thought it would be better to relax
2945 policy and only require the first 3 components to be
2946 specified, in this example "2.3.0". All four
2947 components may still be used if someone wishes to do so.
2953 <sect1 id="f-Version">
2954 <heading><tt>Version</tt></heading>
2957 The version number of a package. The format is:
2958 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2962 The three components here are:
2964 <tag><var>epoch</var></tag>
2967 This is a single (generally small) unsigned integer. It
2968 may be omitted, in which case zero is assumed. If it is
2969 omitted then the <var>upstream_version</var> may not
2974 It is provided to allow mistakes in the version numbers
2975 of older versions of a package, and also a package's
2976 previous version numbering schemes, to be left behind.
2980 <tag><var>upstream_version</var></tag>
2983 This is the main part of the version number. It is
2984 usually the version number of the original ("upstream")
2985 package from which the <file>.deb</file> file has been made,
2986 if this is applicable. Usually this will be in the same
2987 format as that specified by the upstream author(s);
2988 however, it may need to be reformatted to fit into the
2989 package management system's format and comparison
2994 The comparison behavior of the package management system
2995 with respect to the <var>upstream_version</var> is
2996 described below. The <var>upstream_version</var>
2997 portion of the version number is mandatory.
3001 The <var>upstream_version</var> may contain only
3002 alphanumerics<footnote>
3003 Alphanumerics are <tt>A-Za-z0-9</tt> only.
3005 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
3006 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
3007 tilde) and should start with a digit. If there is no
3008 <var>debian_revision</var> then hyphens are not allowed;
3009 if there is no <var>epoch</var> then colons are not
3014 <tag><var>debian_revision</var></tag>
3017 This part of the version number specifies the version of
3018 the Debian package based on the upstream version. It
3019 may contain only alphanumerics and the characters
3020 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
3021 tilde) and is compared in the same way as the
3022 <var>upstream_version</var> is.
3026 It is optional; if it isn't present then the
3027 <var>upstream_version</var> may not contain a hyphen.
3028 This format represents the case where a piece of
3029 software was written specifically to be turned into a
3030 Debian package, and so there is only one "debianisation"
3031 of it and therefore no revision indication is required.
3035 It is conventional to restart the
3036 <var>debian_revision</var> at <tt>1</tt> each time the
3037 <var>upstream_version</var> is increased.
3041 The package management system will break the version
3042 number apart at the last hyphen in the string (if there
3043 is one) to determine the <var>upstream_version</var> and
3044 <var>debian_revision</var>. The absence of a
3045 <var>debian_revision</var> is equivalent to a
3046 <var>debian_revision</var> of <tt>0</tt>.
3053 When comparing two version numbers, first the <var>epoch</var>
3054 of each are compared, then the <var>upstream_version</var> if
3055 <var>epoch</var> is equal, and then <var>debian_revision</var>
3056 if <var>upstream_version</var> is also equal.
3057 <var>epoch</var> is compared numerically. The
3058 <var>upstream_version</var> and <var>debian_revision</var>
3059 parts are compared by the package management system using the
3060 following algorithm:
3064 The strings are compared from left to right.
3068 First the initial part of each string consisting entirely of
3069 non-digit characters is determined. These two parts (one of
3070 which may be empty) are compared lexically. If a difference
3071 is found it is returned. The lexical comparison is a
3072 comparison of ASCII values modified so that all the letters
3073 sort earlier than all the non-letters and so that a tilde
3074 sorts before anything, even the end of a part. For example,
3075 the following parts are in sorted order from earliest to
3076 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
3077 <tt>a</tt>.<footnote>
3078 One common use of <tt>~</tt> is for upstream pre-releases.
3079 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
3080 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
3085 Then the initial part of the remainder of each string which
3086 consists entirely of digit characters is determined. The
3087 numerical values of these two parts are compared, and any
3088 difference found is returned as the result of the comparison.
3089 For these purposes an empty string (which can only occur at
3090 the end of one or both version strings being compared) counts
3095 These two steps (comparing and removing initial non-digit
3096 strings and initial digit strings) are repeated until a
3097 difference is found or both strings are exhausted.
3101 Note that the purpose of epochs is to allow us to leave behind
3102 mistakes in version numbering, and to cope with situations
3103 where the version numbering scheme changes. It is
3104 <em>not</em> intended to cope with version numbers containing
3105 strings of letters which the package management system cannot
3106 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
3107 silly orderings.<footnote>
3108 The author of this manual has heard of a package whose
3109 versions went <tt>1.1</tt>, <tt>1.2</tt>, <tt>1.3</tt>,
3110 <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>, <tt>2</tt> and so
3116 <sect1 id="f-Description">
3117 <heading><tt>Description</tt></heading>
3120 In a source or binary control file, the <tt>Description</tt>
3121 field contains a description of the binary package, consisting
3122 of two parts, the synopsis or the short description, and the
3123 long description. The field's format is as follows:
3128 Description: <single line synopsis>
3129 <extended description over several lines>
3134 The lines in the extended description can have these formats:
3140 Those starting with a single space are part of a paragraph.
3141 Successive lines of this form will be word-wrapped when
3142 displayed. The leading space will usually be stripped off.
3146 Those starting with two or more spaces. These will be
3147 displayed verbatim. If the display cannot be panned
3148 horizontally, the displaying program will line wrap them "hard"
3149 (i.e., without taking account of word breaks). If it can they
3150 will be allowed to trail off to the right. None, one or two
3151 initial spaces may be deleted, but the number of spaces
3152 deleted from each line will be the same (so that you can have
3153 indenting work correctly, for example).
3157 Those containing a single space followed by a single full stop
3158 character. These are rendered as blank lines. This is the
3159 <em>only</em> way to get a blank line<footnote>
3160 Completely empty lines will not be rendered as blank lines.
3161 Instead, they will cause the parser to think you're starting
3162 a whole new record in the control file, and will therefore
3163 likely abort with an error.
3168 Those containing a space, a full stop and some more characters.
3169 These are for future expansion. Do not use them.
3175 Do not use tab characters. Their effect is not predictable.
3179 See <ref id="descriptions"> for further information on this.
3183 In a <file>.changes</file> file, the <tt>Description</tt>
3184 field contains a summary of the descriptions for the packages
3185 being uploaded. For this case, the first line of the field
3186 value (the part on the same line as <tt>Description:</tt>) is
3187 always empty. The content of the field is expressed as
3188 continuation lines, one line per package. Each line is
3189 indented by one space and contains the name of a binary
3190 package, a space, a hyphen (<tt>-</tt>), a space, and the
3191 short description line from that package.
3195 <sect1 id="f-Distribution">
3196 <heading><tt>Distribution</tt></heading>
3199 In a <file>.changes</file> file or parsed changelog output
3200 this contains the (space-separated) name(s) of the
3201 distribution(s) where this version of the package should
3202 be installed. Valid distributions are determined by the
3203 archive maintainers.<footnote>
3204 Example distribution names in the Debian archive used in
3205 <file>.changes</file> files are:
3206 <taglist compact="compact">
3207 <tag><em>unstable</em></tag>
3209 This distribution value refers to the
3210 <em>developmental</em> part of the Debian distribution
3211 tree. Most new packages, new upstream versions of
3212 packages and bug fixes go into the <em>unstable</em>
3216 <tag><em>experimental</em></tag>
3218 The packages with this distribution value are deemed
3219 by their maintainers to be high risk. Oftentimes they
3220 represent early beta or developmental packages from
3221 various sources that the maintainers want people to
3222 try, but are not ready to be a part of the other parts
3223 of the Debian distribution tree.
3228 Others are used for updating stable releases or for
3229 security uploads. More information is available in the
3230 Debian Developer's Reference, section "The Debian
3234 The Debian archive software only supports listing a single
3235 distribution. Migration of packages to other distributions is
3236 handled outside of the upload process.
3241 <heading><tt>Date</tt></heading>
3244 This field includes the date the package was built or last
3245 edited. It must be in the same format as the <var>date</var>
3246 in a <file>debian/changelog</file> entry.
3250 The value of this field is usually extracted from the
3251 <file>debian/changelog</file> file - see
3252 <ref id="dpkgchangelog">).
3256 <sect1 id="f-Format">
3257 <heading><tt>Format</tt></heading>
3260 This field specifies a format revision for the file.
3261 The most current format described in the Policy Manual
3262 is version <strong>1.5</strong>. The syntax of the
3263 format value is the same as that of a package version
3264 number except that no epoch or Debian revision is allowed
3265 - see <ref id="f-Version">.
3269 <sect1 id="f-Urgency">
3270 <heading><tt>Urgency</tt></heading>
3273 This is a description of how important it is to upgrade to
3274 this version from previous ones. It consists of a single
3275 keyword taking one of the values <tt>low</tt>,
3276 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3277 <tt>critical</tt><footnote>
3278 Other urgency values are supported with configuration
3279 changes in the archive software but are not used in Debian.
3280 The urgency affects how quickly a package will be considered
3281 for inclusion into the <tt>testing</tt> distribution and
3282 gives an indication of the importance of any fixes included
3283 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3284 treated as synonymous.
3285 </footnote> (not case-sensitive) followed by an optional
3286 commentary (separated by a space) which is usually in
3287 parentheses. For example:
3290 Urgency: low (HIGH for users of diversions)
3296 The value of this field is usually extracted from the
3297 <file>debian/changelog</file> file - see
3298 <ref id="dpkgchangelog">.
3302 <sect1 id="f-Changes">
3303 <heading><tt>Changes</tt></heading>
3306 This field contains the human-readable changes data, describing
3307 the differences between the last version and the current one.
3311 The first line of the field value (the part on the same line
3312 as <tt>Changes:</tt>) is always empty. The content of the
3313 field is expressed as continuation lines, with each line
3314 indented by at least one space. Blank lines must be
3315 represented by a line consisting only of a space and a full
3320 The value of this field is usually extracted from the
3321 <file>debian/changelog</file> file - see
3322 <ref id="dpkgchangelog">).
3326 Each version's change information should be preceded by a
3327 "title" line giving at least the version, distribution(s)
3328 and urgency, in a human-readable way.
3332 If data from several versions is being returned the entry
3333 for the most recent version should be returned first, and
3334 entries should be separated by the representation of a
3335 blank line (the "title" line may also be followed by the
3336 representation of a blank line).
3340 <sect1 id="f-Binary">
3341 <heading><tt>Binary</tt></heading>
3344 This field is a list of binary packages. Its syntax and
3345 meaning varies depending on the control file in which it
3350 When it appears in the <file>.dsc</file> file, it lists binary
3351 packages which a source package can produce, separated by
3353 A space after each comma is conventional.
3354 </footnote>. It may span multiple lines. The source package
3355 does not necessarily produce all of these binary packages for
3356 every architecture. The source control file doesn't contain
3357 details of which architectures are appropriate for which of
3358 the binary packages.
3362 When it appears in a <file>.changes</file> file, it lists the
3363 names of the binary packages being uploaded, separated by
3364 whitespace (not commas). It may span multiple lines.
3368 <sect1 id="f-Installed-Size">
3369 <heading><tt>Installed-Size</tt></heading>
3372 This field appears in the control files of binary packages,
3373 and in the <file>Packages</file> files. It gives an estimate
3374 of the total amount of disk space required to install the
3375 named package. Actual installed size may vary based on block
3376 size, file system properties, or actions taken by package
3381 The disk space is given as the integer value of the estimated
3382 installed size in bytes, divided by 1024 and rounded up.
3386 <sect1 id="f-Files">
3387 <heading><tt>Files</tt></heading>
3390 This field contains a list of files with information about
3391 each one. The exact information and syntax varies with
3396 In all cases, Files is a multiline field. The first line of
3397 the field value (the part on the same line as <tt>Files:</tt>)
3398 is always empty. The content of the field is expressed as
3399 continuation lines, one line per file. Each line must be
3400 indented by one space and contain a number of sub-fields,
3401 separated by spaces, as described below.
3405 In the <file>.dsc</file> file, each line contains the MD5
3406 checksum, size and filename of the tar file and (if
3407 applicable) diff file which make up the remainder of the
3408 source package<footnote>
3409 That is, the parts which are not the <tt>.dsc</tt>.
3410 </footnote>. For example:
3413 c6f698f19f2a2aa07dbb9bbda90a2754 571925 example_1.2.orig.tar.gz
3414 938512f08422f3509ff36f125f5873ba 6220 example_1.2-1.diff.gz
3416 The exact forms of the filenames are described
3417 in <ref id="pkg-sourcearchives">.
3421 In the <file>.changes</file> file this contains one line per
3422 file being uploaded. Each line contains the MD5 checksum,
3423 size, section and priority and the filename. For example:
3426 4c31ab7bfc40d3cf49d7811987390357 1428 text extra example_1.2-1.dsc
3427 c6f698f19f2a2aa07dbb9bbda90a2754 571925 text extra example_1.2.orig.tar.gz
3428 938512f08422f3509ff36f125f5873ba 6220 text extra example_1.2-1.diff.gz
3429 7c98fe853b3bbb47a00e5cd129b6cb56 703542 text extra example_1.2-1_i386.deb
3431 The <qref id="f-Section">section</qref>
3432 and <qref id="f-Priority">priority</qref> are the values of
3433 the corresponding fields in the main source control file. If
3434 no section or priority is specified then <tt>-</tt> should be
3435 used, though section and priority values must be specified for
3436 new packages to be installed properly.
3440 The special value <tt>byhand</tt> for the section in a
3441 <tt>.changes</tt> file indicates that the file in question
3442 is not an ordinary package file and must by installed by
3443 hand by the distribution maintainers. If the section is
3444 <tt>byhand</tt> the priority should be <tt>-</tt>.
3448 If a new Debian revision of a package is being shipped and
3449 no new original source archive is being distributed the
3450 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3451 entry for the original source archive
3452 <file><var>package</var>_<var>upstream-version</var>.orig.tar.gz</file>,
3453 but the <file>.changes</file> file should leave it out. In
3454 this case the original source archive on the distribution
3455 site must match exactly, byte-for-byte, the original
3456 source archive which was used to generate the
3457 <file>.dsc</file> file and diff which are being uploaded.</p>
3460 <sect1 id="f-Closes">
3461 <heading><tt>Closes</tt></heading>
3464 A space-separated list of bug report numbers that the upload
3465 governed by the .changes file closes.
3469 <sect1 id="f-Homepage">
3470 <heading><tt>Homepage</tt></heading>
3473 The URL of the web site for this package, preferably (when
3474 applicable) the site from which the original source can be
3475 obtained and any additional upstream documentation or
3476 information may be found. The content of this field is a
3477 simple URL without any surrounding characters such as
3482 <sect1 id="f-Checksums">
3483 <heading><tt>Checksums-Sha1</tt>
3484 and <tt>Checksums-Sha256</tt></heading>
3487 These fields contain a list of files with a checksum and size
3488 for each one. Both <tt>Checksums-Sha1</tt>
3489 and <tt>Checksums-Sha256</tt> have the same syntax and differ
3490 only in the checksum algorithm used: SHA-1
3491 for <tt>Checksums-Sha1</tt> and SHA-256
3492 for <tt>Checksums-Sha256</tt>.
3496 <tt>Checksums-Sha1</tt> and <tt>Checksums-Sha256</tt> are
3497 multiline fields. The first line of the field value (the part
3498 on the same line as <tt>Checksums-Sha1:</tt>
3499 or <tt>Checksums-Sha256:</tt>) is always empty. The content
3500 of the field is expressed as continuation lines, one line per
3501 file. Each line consists of the checksum, a space, the file
3502 size, a space, and the file name. For example (from
3503 a <file>.changes</file> file):
3506 1f418afaa01464e63cc1ee8a66a05f0848bd155c 1276 example_1.0-1.dsc
3507 a0ed1456fad61116f868b1855530dbe948e20f06 171602 example_1.0.orig.tar.gz
3508 5e86ecf0671e113b63388dac81dd8d00e00ef298 6137 example_1.0-1.debian.tar.gz
3509 71a0ff7da0faaf608481195f9cf30974b142c183 548402 example_1.0-1_i386.deb
3511 ac9d57254f7e835bed299926fd51bf6f534597cc3fcc52db01c4bffedae81272 1276 example_1.0-1.dsc
3512 0d123be7f51e61c4bf15e5c492b484054be7e90f3081608a5517007bfb1fd128 171602 example_1.0.orig.tar.gz
3513 f54ae966a5f580571ae7d9ef5e1df0bd42d63e27cb505b27957351a495bc6288 6137 example_1.0-1.debian.tar.gz
3514 3bec05c03974fdecd11d020fc2e8250de8404867a8a2ce865160c250eb723664 548402 example_1.0-1_i386.deb
3519 In the <file>.dsc</file> file, these fields should list all
3520 files that make up the source package. In
3521 the <file>.changes</file> file, these fields should list all
3522 files being uploaded. The list of files in these fields
3523 must match the list of files in the <tt>Files</tt> field.
3530 <heading>User-defined fields</heading>
3533 Additional user-defined fields may be added to the
3534 source package control file. Such fields will be
3535 ignored, and not copied to (for example) binary or
3536 source package control files or upload control files.
3540 If you wish to add additional unsupported fields to
3541 these output files you should use the mechanism
3546 Fields in the main source control information file with
3547 names starting <tt>X</tt>, followed by one or more of
3548 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3549 be copied to the output files. Only the part of the
3550 field name after the hyphen will be used in the output
3551 file. Where the letter <tt>B</tt> is used the field
3552 will appear in binary package control files, where the
3553 letter <tt>S</tt> is used in source package control
3554 files and where <tt>C</tt> is used in upload control
3555 (<tt>.changes</tt>) files.
3559 For example, if the main source information control file
3562 XBS-Comment: I stand between the candle and the star.
3564 then the binary and source package control files will contain the
3567 Comment: I stand between the candle and the star.
3576 <chapt id="maintainerscripts">
3577 <heading>Package maintainer scripts and installation procedure</heading>
3580 <heading>Introduction to package maintainer scripts</heading>
3583 It is possible to supply scripts as part of a package which
3584 the package management system will run for you when your
3585 package is installed, upgraded or removed.
3589 These scripts are the files <prgn>preinst</prgn>,
3590 <prgn>postinst</prgn>, <prgn>prerm</prgn> and
3591 <prgn>postrm</prgn> in the control area of the package.
3592 They must be proper executable files; if they are scripts
3593 (which is recommended), they must start with the usual
3594 <tt>#!</tt> convention. They should be readable and
3595 executable by anyone, and must not be world-writable.
3599 The package management system looks at the exit status from
3600 these scripts. It is important that they exit with a
3601 non-zero status if there is an error, so that the package
3602 management system can stop its processing. For shell
3603 scripts this means that you <em>almost always</em> need to
3604 use <tt>set -e</tt> (this is usually true when writing shell
3605 scripts, in fact). It is also important, of course, that
3606 they exit with a zero status if everything went well.
3610 Additionally, packages interacting with users using
3611 <tt>debconf</tt> in the <prgn>postinst</prgn> script should
3612 install a <prgn>config</prgn> script in the control area,
3613 see <ref id="maintscriptprompt"> for details.
3617 When a package is upgraded a combination of the scripts from
3618 the old and new packages is called during the upgrade
3619 procedure. If your scripts are going to be at all
3620 complicated you need to be aware of this, and may need to
3621 check the arguments to your scripts.
3625 Broadly speaking the <prgn>preinst</prgn> is called before
3626 (a particular version of) a package is installed, and the
3627 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3628 before (a version of) a package is removed and the
3629 <prgn>postrm</prgn> afterwards.
3633 Programs called from maintainer scripts should not normally
3634 have a path prepended to them. Before installation is
3635 started, the package management system checks to see if the
3636 programs <prgn>ldconfig</prgn>,
3637 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3638 and <prgn>update-rc.d</prgn> can be found via the
3639 <tt>PATH</tt> environment variable. Those programs, and any
3640 other program that one would expect to be in the
3641 <tt>PATH</tt>, should thus be invoked without an absolute
3642 pathname. Maintainer scripts should also not reset the
3643 <tt>PATH</tt>, though they might choose to modify it by
3644 prepending or appending package-specific directories. These
3645 considerations really apply to all shell scripts.</p>
3648 <sect id="idempotency">
3649 <heading>Maintainer scripts idempotency</heading>
3652 It is necessary for the error recovery procedures that the
3653 scripts be idempotent. This means that if it is run
3654 successfully, and then it is called again, it doesn't bomb
3655 out or cause any harm, but just ensures that everything is
3656 the way it ought to be. If the first call failed, or
3657 aborted half way through for some reason, the second call
3658 should merely do the things that were left undone the first
3659 time, if any, and exit with a success status if everything
3661 This is so that if an error occurs, the user interrupts
3662 <prgn>dpkg</prgn> or some other unforeseen circumstance
3663 happens you don't leave the user with a badly-broken
3664 package when <prgn>dpkg</prgn> attempts to repeat the
3670 <sect id="controllingterminal">
3671 <heading>Controlling terminal for maintainer scripts</heading>
3674 Maintainer scripts are not guaranteed to run with a controlling
3675 terminal and may not be able to interact with the user. They
3676 must be able to fall back to noninteractive behavior if no
3677 controlling terminal is available. Maintainer scripts that
3678 prompt via a program conforming to the Debian Configuration
3679 Management Specification (see <ref id="maintscriptprompt">) may
3680 assume that program will handle falling back to noninteractive
3685 For high-priority prompts without a reasonable default answer,
3686 maintainer scripts may abort if there is no controlling
3687 terminal. However, this situation should be avoided if at all
3688 possible, since it prevents automated or unattended installs.
3689 In most cases, users will consider this to be a bug in the
3694 <sect id="exitstatus">
3695 <heading>Exit status</heading>
3698 Each script must return a zero exit status for
3699 success, or a nonzero one for failure, since the package
3700 management system looks for the exit status of these scripts
3701 and determines what action to take next based on that datum.
3705 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3710 <list compact="compact">
3712 <var>new-preinst</var> <tt>install</tt>
3715 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3718 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3721 <var>old-preinst</var> <tt>abort-upgrade</tt>
3722 <var>new-version</var>
3727 <list compact="compact">
3729 <var>postinst</var> <tt>configure</tt>
3730 <var>most-recently-configured-version</var>
3733 <var>old-postinst</var> <tt>abort-upgrade</tt>
3734 <var>new-version</var>
3737 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3738 <tt>in-favour</tt> <var>package</var>
3739 <var>new-version</var>
3742 <var>postinst</var> <tt>abort-remove</tt>
3745 <var>deconfigured's-postinst</var>
3746 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3747 <var>failed-install-package</var> <var>version</var>
3748 [<tt>removing</tt> <var>conflicting-package</var>
3754 <list compact="compact">
3756 <var>prerm</var> <tt>remove</tt>
3759 <var>old-prerm</var> <tt>upgrade</tt>
3760 <var>new-version</var>
3763 <var>new-prerm</var> <tt>failed-upgrade</tt>
3764 <var>old-version</var>
3767 <var>conflictor's-prerm</var> <tt>remove</tt>
3768 <tt>in-favour</tt> <var>package</var>
3769 <var>new-version</var>
3772 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3773 <tt>in-favour</tt> <var>package-being-installed</var>
3774 <var>version</var> [<tt>removing</tt>
3775 <var>conflicting-package</var>
3781 <list compact="compact">
3783 <var>postrm</var> <tt>remove</tt>
3786 <var>postrm</var> <tt>purge</tt>
3789 <var>old-postrm</var> <tt>upgrade</tt>
3790 <var>new-version</var>
3793 <var>new-postrm</var> <tt>failed-upgrade</tt>
3794 <var>old-version</var>
3797 <var>new-postrm</var> <tt>abort-install</tt>
3800 <var>new-postrm</var> <tt>abort-install</tt>
3801 <var>old-version</var>
3804 <var>new-postrm</var> <tt>abort-upgrade</tt>
3805 <var>old-version</var>
3808 <var>disappearer's-postrm</var> <tt>disappear</tt>
3809 <var>overwriter</var>
3810 <var>overwriter-version</var>
3816 <sect id="unpackphase">
3817 <heading>Details of unpack phase of installation or upgrade</heading>
3820 The procedure on installation/upgrade/overwrite/disappear
3821 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3822 stage of <tt>dpkg --install</tt>) is as follows. In each
3823 case, if a major error occurs (unless listed below) the
3824 actions are, in general, run backwards - this means that the
3825 maintainer scripts are run with different arguments in
3826 reverse order. These are the "error unwind" calls listed
3833 If a version of the package is already installed, call
3834 <example compact="compact">
3835 <var>old-prerm</var> upgrade <var>new-version</var>
3839 If the script runs but exits with a non-zero
3840 exit status, <prgn>dpkg</prgn> will attempt:
3841 <example compact="compact">
3842 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3844 If this works, the upgrade continues. If this
3845 does not work, the error unwind:
3846 <example compact="compact">
3847 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3849 If this works, then the old-version is
3850 "Installed", if not, the old version is in a
3851 "Half-Configured" state.
3857 If a "conflicting" package is being removed at the same time,
3858 or if any package will be broken (due to <tt>Breaks</tt>):
3861 If <tt>--auto-deconfigure</tt> is
3862 specified, call, for each package to be deconfigured
3863 due to <tt>Breaks</tt>:
3864 <example compact="compact">
3865 <var>deconfigured's-prerm</var> deconfigure \
3866 in-favour <var>package-being-installed</var> <var>version</var>
3869 <example compact="compact">
3870 <var>deconfigured's-postinst</var> abort-deconfigure \
3871 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3873 The deconfigured packages are marked as
3874 requiring configuration, so that if
3875 <tt>--install</tt> is used they will be
3876 configured again if possible.
3879 If any packages depended on a conflicting
3880 package being removed and <tt>--auto-deconfigure</tt> is
3881 specified, call, for each such package:
3882 <example compact="compact">
3883 <var>deconfigured's-prerm</var> deconfigure \
3884 in-favour <var>package-being-installed</var> <var>version</var> \
3885 removing <var>conflicting-package</var> <var>version</var>
3888 <example compact="compact">
3889 <var>deconfigured's-postinst</var> abort-deconfigure \
3890 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3891 removing <var>conflicting-package</var> <var>version</var>
3893 The deconfigured packages are marked as
3894 requiring configuration, so that if
3895 <tt>--install</tt> is used they will be
3896 configured again if possible.
3899 To prepare for removal of each conflicting package, call:
3900 <example compact="compact">
3901 <var>conflictor's-prerm</var> remove \
3902 in-favour <var>package</var> <var>new-version</var>
3905 <example compact="compact">
3906 <var>conflictor's-postinst</var> abort-remove \
3907 in-favour <var>package</var> <var>new-version</var>
3916 If the package is being upgraded, call:
3917 <example compact="compact">
3918 <var>new-preinst</var> upgrade <var>old-version</var>
3920 If this fails, we call:
3922 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3929 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3931 is called. If this works, then the old version
3932 is in an "Installed" state, or else it is left
3933 in an "Unpacked" state.
3938 If it fails, then the old version is left
3939 in an "Half-Installed" state.
3946 Otherwise, if the package had some configuration
3947 files from a previous version installed (i.e., it
3948 is in the "configuration files only" state):
3949 <example compact="compact">
3950 <var>new-preinst</var> install <var>old-version</var>
3954 <var>new-postrm</var> abort-install <var>old-version</var>
3956 If this fails, the package is left in a
3957 "Half-Installed" state, which requires a
3958 reinstall. If it works, the packages is left in
3959 a "Config-Files" state.
3962 Otherwise (i.e., the package was completely purged):
3963 <example compact="compact">
3964 <var>new-preinst</var> install
3967 <example compact="compact">
3968 <var>new-postrm</var> abort-install
3970 If the error-unwind fails, the package is in a
3971 "Half-Installed" phase, and requires a
3972 reinstall. If the error unwind works, the
3973 package is in a not installed state.
3980 The new package's files are unpacked, overwriting any
3981 that may be on the system already, for example any
3982 from the old version of the same package or from
3983 another package. Backups of the old files are kept
3984 temporarily, and if anything goes wrong the package
3985 management system will attempt to put them back as
3986 part of the error unwind.
3990 It is an error for a package to contain files which
3991 are on the system in another package, unless
3992 <tt>Replaces</tt> is used (see <ref id="replaces">).
3994 The following paragraph is not currently the case:
3995 Currently the <tt>- - force-overwrite</tt> flag is
3996 enabled, downgrading it to a warning, but this may not
4002 It is a more serious error for a package to contain a
4003 plain file or other kind of non-directory where another
4004 package has a directory (again, unless
4005 <tt>Replaces</tt> is used). This error can be
4006 overridden if desired using
4007 <tt>--force-overwrite-dir</tt>, but this is not
4012 Packages which overwrite each other's files produce
4013 behavior which, though deterministic, is hard for the
4014 system administrator to understand. It can easily
4015 lead to "missing" programs if, for example, a package
4016 is installed which overwrites a file from another
4017 package, and is then removed again.<footnote>
4018 Part of the problem is due to what is arguably a
4019 bug in <prgn>dpkg</prgn>.
4024 A directory will never be replaced by a symbolic link
4025 to a directory or vice versa; instead, the existing
4026 state (symlink or not) will be left alone and
4027 <prgn>dpkg</prgn> will follow the symlink if there is
4036 If the package is being upgraded, call
4037 <example compact="compact">
4038 <var>old-postrm</var> upgrade <var>new-version</var>
4042 If this fails, <prgn>dpkg</prgn> will attempt:
4043 <example compact="compact">
4044 <var>new-postrm</var> failed-upgrade <var>old-version</var>
4046 If this works, installation continues. If not,
4048 <example compact="compact">
4049 <var>old-preinst</var> abort-upgrade <var>new-version</var>
4051 If this fails, the old version is left in a
4052 "Half-Installed" state. If it works, dpkg now
4054 <example compact="compact">
4055 <var>new-postrm</var> abort-upgrade <var>old-version</var>
4057 If this fails, the old version is left in a
4058 "Half-Installed" state. If it works, dpkg now
4060 <example compact="compact">
4061 <var>old-postinst</var> abort-upgrade <var>new-version</var>
4063 If this fails, the old version is in an
4070 This is the point of no return - if
4071 <prgn>dpkg</prgn> gets this far, it won't back off
4072 past this point if an error occurs. This will
4073 leave the package in a fairly bad state, which
4074 will require a successful re-installation to clear
4075 up, but it's when <prgn>dpkg</prgn> starts doing
4076 things that are irreversible.
4081 Any files which were in the old version of the package
4082 but not in the new are removed.
4086 The new file list replaces the old.
4090 The new maintainer scripts replace the old.
4094 Any packages all of whose files have been overwritten
4095 during the installation, and which aren't required for
4096 dependencies, are considered to have been removed.
4097 For each such package
4100 <prgn>dpkg</prgn> calls:
4101 <example compact="compact">
4102 <var>disappearer's-postrm</var> disappear \
4103 <var>overwriter</var> <var>overwriter-version</var>
4107 The package's maintainer scripts are removed.
4110 It is noted in the status database as being in a
4111 sane state, namely not installed (any conffiles
4112 it may have are ignored, rather than being
4113 removed by <prgn>dpkg</prgn>). Note that
4114 disappearing packages do not have their prerm
4115 called, because <prgn>dpkg</prgn> doesn't know
4116 in advance that the package is going to
4123 Any files in the package we're unpacking that are also
4124 listed in the file lists of other packages are removed
4125 from those lists. (This will lobotomize the file list
4126 of the "conflicting" package if there is one.)
4130 The backup files made during installation, above, are
4136 The new package's status is now sane, and recorded as
4141 Here is another point of no return - if the
4142 conflicting package's removal fails we do not unwind
4143 the rest of the installation; the conflicting package
4144 is left in a half-removed limbo.
4149 If there was a conflicting package we go and do the
4150 removal actions (described below), starting with the
4151 removal of the conflicting package's files (any that
4152 are also in the package being installed have already
4153 been removed from the conflicting package's file list,
4154 and so do not get removed now).
4160 <sect id="configdetails"><heading>Details of configuration</heading>
4163 When we configure a package (this happens with <tt>dpkg
4164 --install</tt> and <tt>dpkg --configure</tt>), we first
4165 update any <tt>conffile</tt>s and then call:
4166 <example compact="compact">
4167 <var>postinst</var> configure <var>most-recently-configured-version</var>
4172 No attempt is made to unwind after errors during
4173 configuration. If the configuration fails, the package is in
4174 a "Failed Config" state, and an error message is generated.
4178 If there is no most recently configured version
4179 <prgn>dpkg</prgn> will pass a null argument.
4182 Historical note: Truly ancient (pre-1997) versions of
4183 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4184 (including the angle brackets) in this case. Even older
4185 ones did not pass a second argument at all, under any
4186 circumstance. Note that upgrades using such an old dpkg
4187 version are unlikely to work for other reasons, even if
4188 this old argument behavior is handled by your postinst script.
4194 <sect id="removedetails"><heading>Details of removal and/or
4195 configuration purging</heading>
4201 <example compact="compact">
4202 <var>prerm</var> remove
4206 If prerm fails during replacement due to conflict
4208 <var>conflictor's-postinst</var> abort-remove \
4209 in-favour <var>package</var> <var>new-version</var>
4213 <var>postinst</var> abort-remove
4217 If this fails, the package is in a "Half-Configured"
4218 state, or else it remains "Installed".
4222 The package's files are removed (except <tt>conffile</tt>s).
4225 <example compact="compact">
4226 <var>postrm</var> remove
4230 If it fails, there's no error unwind, and the package is in
4231 an "Half-Installed" state.
4236 All the maintainer scripts except the <prgn>postrm</prgn>
4241 If we aren't purging the package we stop here. Note
4242 that packages which have no <prgn>postrm</prgn> and no
4243 <tt>conffile</tt>s are automatically purged when
4244 removed, as there is no difference except for the
4245 <prgn>dpkg</prgn> status.
4249 The <tt>conffile</tt>s and any backup files
4250 (<tt>~</tt>-files, <tt>#*#</tt> files,
4251 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4256 <example compact="compact">
4257 <var>postrm</var> purge
4261 If this fails, the package remains in a "Config-Files"
4266 The package's file list is removed.
4275 <chapt id="relationships">
4276 <heading>Declaring relationships between packages</heading>
4278 <sect id="depsyntax">
4279 <heading>Syntax of relationship fields</heading>
4282 These fields all have a uniform syntax. They are a list of
4283 package names separated by commas.
4287 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4288 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4289 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4290 control file fields of the package, which declare
4291 dependencies on other packages, the package names listed may
4292 also include lists of alternative package names, separated
4293 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4294 if any one of the alternative packages is installed, that
4295 part of the dependency is considered to be satisfied.
4299 All of the fields except for <tt>Provides</tt> may restrict
4300 their applicability to particular versions of each named
4301 package. This is done in parentheses after each individual
4302 package name; the parentheses should contain a relation from
4303 the list below followed by a version number, in the format
4304 described in <ref id="f-Version">.
4308 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4309 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4310 strictly earlier, earlier or equal, exactly equal, later or
4311 equal and strictly later, respectively. The deprecated
4312 forms <tt><</tt> and <tt>></tt> were used to mean
4313 earlier/later or equal, rather than strictly earlier/later,
4314 so they should not appear in new packages (though
4315 <prgn>dpkg</prgn> still supports them).
4319 Whitespace may appear at any point in the version
4320 specification subject to the rules in <ref
4321 id="controlsyntax">, and must appear where it's necessary to
4322 disambiguate; it is not otherwise significant. All of the
4323 relationship fields may span multiple lines. For
4324 consistency and in case of future changes to
4325 <prgn>dpkg</prgn> it is recommended that a single space be
4326 used after a version relationship and before a version
4327 number; it is also conventional to put a single space after
4328 each comma, on either side of each vertical bar, and before
4329 each open parenthesis. When wrapping a relationship field, it
4330 is conventional to do so after a comma and before the space
4331 following that comma.
4335 For example, a list of dependencies might appear as:
4336 <example compact="compact">
4339 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4344 All fields that specify build-time relationships
4345 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4346 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
4347 may be restricted to a certain set of architectures. This
4348 is indicated in brackets after each individual package name and
4349 the optional version specification. The brackets enclose a
4350 list of Debian architecture names separated by whitespace.
4351 Exclamation marks may be prepended to each of the names.
4352 (It is not permitted for some names to be prepended with
4353 exclamation marks while others aren't.) If the current Debian
4354 host architecture is not in this list and there are no
4355 exclamation marks in the list, or it is in the list with a
4356 prepended exclamation mark, the package name and the
4357 associated version specification are ignored completely for
4358 the purposes of defining the relationships.
4363 <example compact="compact">
4365 Build-Depends-Indep: texinfo
4366 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4367 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4369 requires <tt>kernel-headers-2.2.10</tt> on all architectures
4370 other than hurd-i386 and requires <tt>hurd-dev</tt> and
4371 <tt>gnumach-dev</tt> only on hurd-i386.
4375 If the architecture-restricted dependency is part of a set of
4376 alternatives using <tt>|</tt>, that alternative is ignored
4377 completely on architectures that do not match the restriction.
4379 <example compact="compact">
4380 Build-Depends: foo [!i386] | bar [!amd64]
4382 is equivalent to <tt>bar</tt> on the i386 architecture, to
4383 <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
4384 bar</tt> on all other architectures.
4388 All fields that specify build-time relationships may also be
4389 restricted to a certain set of architectures using architecture
4390 wildcards. The syntax for declaring such restrictions is the
4391 same as declaring restrictions using a certain set of
4392 architectures without architecture wildcards. For example:
4393 <example compact="compact">
4394 Build-Depends: foo [linux-any], bar [any-i386], baz [!linux-any]
4396 is equivalent to <tt>foo</tt> on architectures using the Linux
4397 kernel and any cpu, <tt>bar</tt> on architectures using any
4398 kernel and an i386 cpu, and <tt>baz</tt> on any architecture
4399 using a kernel other than Linux.
4403 Note that the binary package relationship fields such as
4404 <tt>Depends</tt> appear in one of the binary package
4405 sections of the control file, whereas the build-time
4406 relationships such as <tt>Build-Depends</tt> appear in the
4407 source package section of the control file (which is the
4412 <sect id="binarydeps">
4413 <heading>Binary Dependencies - <tt>Depends</tt>,
4414 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4415 <tt>Pre-Depends</tt>
4419 Packages can declare in their control file that they have
4420 certain relationships to other packages - for example, that
4421 they may not be installed at the same time as certain other
4422 packages, and/or that they depend on the presence of others.
4426 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4427 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4428 <tt>Breaks</tt> and <tt>Conflicts</tt> control file fields.
4429 <tt>Breaks</tt> is described in <ref id="breaks">, and
4430 <tt>Conflicts</tt> is described in <ref id="conflicts">. The
4431 rest are described below.
4435 These seven fields are used to declare a dependency
4436 relationship by one package on another. Except for
4437 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4438 depending (binary) package's control file.
4439 (<tt>Enhances</tt> appears in the recommending package's
4440 control file, and <tt>Breaks</tt> appears in the version of
4441 depended-on package which causes the named package to
4446 A <tt>Depends</tt> field takes effect <em>only</em> when a
4447 package is to be configured. It does not prevent a package
4448 being on the system in an unconfigured state while its
4449 dependencies are unsatisfied, and it is possible to replace
4450 a package whose dependencies are satisfied and which is
4451 properly installed with a different version whose
4452 dependencies are not and cannot be satisfied; when this is
4453 done the depending package will be left unconfigured (since
4454 attempts to configure it will give errors) and will not
4455 function properly. If it is necessary, a
4456 <tt>Pre-Depends</tt> field can be used, which has a partial
4457 effect even when a package is being unpacked, as explained
4458 in detail below. (The other three dependency fields,
4459 <tt>Recommends</tt>, <tt>Suggests</tt> and
4460 <tt>Enhances</tt>, are only used by the various front-ends
4461 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4462 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4466 For this reason packages in an installation run are usually
4467 all unpacked first and all configured later; this gives
4468 later versions of packages with dependencies on later
4469 versions of other packages the opportunity to have their
4470 dependencies satisfied.
4474 In case of circular dependencies, since installation or
4475 removal order honoring the dependency order can't be
4476 established, dependency loops are broken at some point
4477 (based on rules below), and some packages may not be able to
4478 rely on their dependencies being present when being
4479 installed or removed, depending on which side of the break
4480 of the circular dependency loop they happen to be on. If one
4481 of the packages in the loop has no postinst script, then the
4482 cycle will be broken at that package, so as to ensure that
4483 all postinst scripts run with the dependencies properly
4484 configured if this is possible. Otherwise the breaking point
4489 The <tt>Depends</tt> field thus allows package maintainers
4490 to impose an order in which packages should be configured.
4494 The meaning of the five dependency fields is as follows:
4496 <tag><tt>Depends</tt></tag>
4499 This declares an absolute dependency. A package will
4500 not be configured unless all of the packages listed in
4501 its <tt>Depends</tt> field have been correctly
4506 The <tt>Depends</tt> field should be used if the
4507 depended-on package is required for the depending
4508 package to provide a significant amount of
4513 The <tt>Depends</tt> field should also be used if the
4514 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4515 <prgn>postrm</prgn> scripts require the package to be
4516 present in order to run. Note, however, that the
4517 <prgn>postrm</prgn> cannot rely on any non-essential
4518 packages to be present during the <tt>purge</tt>
4522 <tag><tt>Recommends</tt></tag>
4525 This declares a strong, but not absolute, dependency.
4529 The <tt>Recommends</tt> field should list packages
4530 that would be found together with this one in all but
4531 unusual installations.
4535 <tag><tt>Suggests</tt></tag>
4537 This is used to declare that one package may be more
4538 useful with one or more others. Using this field
4539 tells the packaging system and the user that the
4540 listed packages are related to this one and can
4541 perhaps enhance its usefulness, but that installing
4542 this one without them is perfectly reasonable.
4545 <tag><tt>Enhances</tt></tag>
4547 This field is similar to Suggests but works in the
4548 opposite direction. It is used to declare that a
4549 package can enhance the functionality of another
4553 <tag><tt>Pre-Depends</tt></tag>
4556 This field is like <tt>Depends</tt>, except that it
4557 also forces <prgn>dpkg</prgn> to complete installation
4558 of the packages named before even starting the
4559 installation of the package which declares the
4560 pre-dependency, as follows:
4564 When a package declaring a pre-dependency is about to
4565 be <em>unpacked</em> the pre-dependency can be
4566 satisfied if the depended-on package is either fully
4567 configured, <em>or even if</em> the depended-on
4568 package(s) are only unpacked or in the "Half-Configured"
4569 state, provided that they have been configured
4570 correctly at some point in the past (and not removed
4571 or partially removed since). In this case, both the
4572 previously-configured and currently unpacked or
4573 "Half-Configured" versions must satisfy any version
4574 clause in the <tt>Pre-Depends</tt> field.
4578 When the package declaring a pre-dependency is about
4579 to be <em>configured</em>, the pre-dependency will be
4580 treated as a normal <tt>Depends</tt>, that is, it will
4581 be considered satisfied only if the depended-on
4582 package has been correctly configured.
4586 <tt>Pre-Depends</tt> should be used sparingly,
4587 preferably only by packages whose premature upgrade or
4588 installation would hamper the ability of the system to
4589 continue with any upgrade that might be in progress.
4593 <tt>Pre-Depends</tt> are also required if the
4594 <prgn>preinst</prgn> script depends on the named
4595 package. It is best to avoid this situation if
4603 When selecting which level of dependency to use you should
4604 consider how important the depended-on package is to the
4605 functionality of the one declaring the dependency. Some
4606 packages are composed of components of varying degrees of
4607 importance. Such a package should list using
4608 <tt>Depends</tt> the package(s) which are required by the
4609 more important components. The other components'
4610 requirements may be mentioned as Suggestions or
4611 Recommendations, as appropriate to the components' relative
4617 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4620 When one binary package declares that it breaks another,
4621 <prgn>dpkg</prgn> will refuse to allow the package which
4622 declares <tt>Breaks</tt> be installed unless the broken
4623 package is deconfigured first, and it will refuse to
4624 allow the broken package to be reconfigured.
4628 A package will not be regarded as causing breakage merely
4629 because its configuration files are still installed; it must
4630 be at least "Half-Installed".
4634 A special exception is made for packages which declare that
4635 they break their own package name or a virtual package which
4636 they provide (see below): this does not count as a real
4641 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4642 version clause; such a <tt>Breaks</tt> is introduced in the
4643 version of an (implicit or explicit) dependency which
4644 violates an assumption or reveals a bug in earlier versions
4645 of the broken package. This use of <tt>Breaks</tt> will
4646 inform higher-level package management tools that broken
4647 package must be upgraded before the new one.
4651 If the breaking package also overwrites some files from the
4652 older package, it should use <tt>Replaces</tt> (not
4653 <tt>Conflicts</tt>) to ensure this goes smoothly.
4657 <sect id="conflicts">
4658 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4661 When one binary package declares a conflict with another
4662 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4663 refuse to allow them to be installed on the system at the
4668 If one package is to be installed, the other must be removed
4669 first - if the package being installed is marked as
4670 replacing (see <ref id="replaces">) the one on the system,
4671 or the one on the system is marked as deselected, or both
4672 packages are marked <tt>Essential</tt>, then
4673 <prgn>dpkg</prgn> will automatically remove the package
4674 which is causing the conflict, otherwise it will halt the
4675 installation of the new package with an error. This
4676 mechanism is specifically designed to produce an error when
4677 the installed package is <tt>Essential</tt>, but the new
4682 A package will not cause a conflict merely because its
4683 configuration files are still installed; it must be at least
4688 A special exception is made for packages which declare a
4689 conflict with their own package name, or with a virtual
4690 package which they provide (see below): this does not
4691 prevent their installation, and allows a package to conflict
4692 with others providing a replacement for it. You use this
4693 feature when you want the package in question to be the only
4694 package providing some feature.
4698 A <tt>Conflicts</tt> entry should almost never have an
4699 "earlier than" version clause. This would prevent
4700 <prgn>dpkg</prgn> from upgrading or installing the package
4701 which declared such a conflict until the upgrade or removal
4702 of the conflicted-with package had been completed. Instead,
4703 <tt>Breaks</tt> may be used.
4707 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4711 As well as the names of actual ("concrete") packages, the
4712 package relationship fields <tt>Depends</tt>,
4713 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4714 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4715 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4716 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4717 may mention "virtual packages".
4721 A <em>virtual package</em> is one which appears in the
4722 <tt>Provides</tt> control file field of another package.
4723 The effect is as if the package(s) which provide a
4724 particular virtual package name had been listed by name
4725 everywhere the virtual package name appears. (See also <ref
4730 If there are both concrete and virtual packages of the same
4731 name, then the dependency may be satisfied (or the conflict
4732 caused) by either the concrete package with the name in
4733 question or any other concrete package which provides the
4734 virtual package with the name in question. This is so that,
4735 for example, supposing we have
4736 <example compact="compact">
4739 </example> and someone else releases an enhanced version of
4740 the <tt>bar</tt> package they can say:
4741 <example compact="compact">
4745 and the <tt>bar-plus</tt> package will now also satisfy the
4746 dependency for the <tt>foo</tt> package.
4750 If a relationship field has a version number attached
4751 then only real packages will be considered to see whether
4752 the relationship is satisfied (or the prohibition violated,
4753 for a conflict or breakage) - it is assumed that a real
4754 package which provides the virtual package is not of the
4755 "right" version. So, a <tt>Provides</tt> field may not
4756 contain version numbers, and the version number of the
4757 concrete package which provides a particular virtual package
4758 will not be looked at when considering a dependency on or
4759 conflict with the virtual package name.
4763 It is likely that the ability will be added in a future
4764 release of <prgn>dpkg</prgn> to specify a version number for
4765 each virtual package it provides. This feature is not yet
4766 present, however, and is expected to be used only
4771 If you want to specify which of a set of real packages
4772 should be the default to satisfy a particular dependency on
4773 a virtual package, you should list the real package as an
4774 alternative before the virtual one.
4779 <sect id="replaces"><heading>Overwriting files and replacing
4780 packages - <tt>Replaces</tt></heading>
4783 Packages can declare in their control file that they should
4784 overwrite files in certain other packages, or completely
4785 replace other packages. The <tt>Replaces</tt> control file
4786 field has these two distinct purposes.
4789 <sect1><heading>Overwriting files in other packages</heading>
4792 Firstly, as mentioned before, it is usually an error for a
4793 package to contain files which are on the system in
4798 However, if the overwriting package declares that it
4799 <tt>Replaces</tt> the one containing the file being
4800 overwritten, then <prgn>dpkg</prgn> will replace the file
4801 from the old package with that from the new. The file
4802 will no longer be listed as "owned" by the old package.
4806 For example, if a package <package>foo</package> is split
4807 into <package>foo</package> and <package>foo-data</package>
4808 starting at version 1.2-3, <package>foo-data</package> should
4810 <example compact="compact">
4811 Replaces: foo (<< 1.2-3)
4813 in its control file. The package <package>foo</package>
4814 doesn't need any special control fields in this example,
4815 although would generally depend on or
4816 recommend <package>foo-data</package>.
4820 If a package is completely replaced in this way, so that
4821 <prgn>dpkg</prgn> does not know of any files it still
4822 contains, it is considered to have "disappeared". It will
4823 be marked as not wanted on the system (selected for
4824 removal) and not installed. Any <tt>conffile</tt>s
4825 details noted for the package will be ignored, as they
4826 will have been taken over by the overwriting package. The
4827 package's <prgn>postrm</prgn> script will be run with a
4828 special argument to allow the package to do any final
4829 cleanup required. See <ref id="mscriptsinstact">.
4832 Replaces is a one way relationship -- you have to
4833 install the replacing package after the replaced
4840 For this usage of <tt>Replaces</tt>, virtual packages (see
4841 <ref id="virtual">) are not considered when looking at a
4842 <tt>Replaces</tt> field - the packages declared as being
4843 replaced must be mentioned by their real names.
4847 Furthermore, this usage of <tt>Replaces</tt> only takes
4848 effect when both packages are at least partially on the
4849 system at once, so that it can only happen if they do not
4850 conflict or if the conflict has been overridden.
4855 <sect1><heading>Replacing whole packages, forcing their
4859 Secondly, <tt>Replaces</tt> allows the packaging system to
4860 resolve which package should be removed when there is a
4861 conflict - see <ref id="conflicts">. This usage only
4862 takes effect when the two packages <em>do</em> conflict,
4863 so that the two usages of this field do not interfere with
4868 In this situation, the package declared as being replaced
4869 can be a virtual package, so for example, all mail
4870 transport agents (MTAs) would have the following fields in
4871 their control files:
4872 <example compact="compact">
4873 Provides: mail-transport-agent
4874 Conflicts: mail-transport-agent
4875 Replaces: mail-transport-agent
4877 ensuring that only one MTA can be installed at any one
4882 <sect id="sourcebinarydeps">
4883 <heading>Relationships between source and binary packages -
4884 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4885 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4889 Source packages that require certain binary packages to be
4890 installed or absent at the time of building the package
4891 can declare relationships to those binary packages.
4895 This is done using the <tt>Build-Depends</tt>,
4896 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4897 <tt>Build-Conflicts-Indep</tt> control file fields.
4901 Build-dependencies on "build-essential" binary packages can be
4902 omitted. Please see <ref id="pkg-relations"> for more information.
4906 The dependencies and conflicts they define must be satisfied
4907 (as defined earlier for binary packages) in order to invoke
4908 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4910 There is no Build-Depends-Arch; this role is essentially
4911 met with Build-Depends. Anyone building the
4912 <tt>build-indep</tt> and binary-indep<tt></tt> targets is
4913 assumed to be building the whole package, and therefore
4914 installation of all build dependencies is required.
4917 The autobuilders use <tt>dpkg-buildpackage -B</tt>, which
4918 calls <tt>build</tt>, not <tt>build-arch</tt> since it does
4919 not yet know how to check for its existence, and
4920 <tt>binary-arch</tt>. The purpose of the original split
4921 between <tt>Build-Depends</tt> and
4922 <tt>Build-Depends-Indep</tt> was so that the autobuilders
4923 wouldn't need to install extra packages needed only for the
4924 binary-indep targets. But without a build-arch/build-indep
4925 split, this didn't work, since most of the work is done in
4926 the build target, not in the binary target.
4930 <tag><tt>clean</tt>, <tt>build-arch</tt>, and
4931 <tt>binary-arch</tt></tag>
4933 Only the <tt>Build-Depends</tt> and <tt>Build-Conflicts</tt>
4934 fields must be satisfied when these targets are invoked.
4936 <tag><tt>build</tt>, <tt>build-indep</tt>, <tt>binary</tt>,
4937 and <tt>binary-indep</tt></tag>
4939 The <tt>Build-Depends</tt>, <tt>Build-Conflicts</tt>,
4940 <tt>Build-Depends-Indep</tt>, and
4941 <tt>Build-Conflicts-Indep</tt> fields must be satisfied when
4942 these targets are invoked.
4950 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4953 Packages containing shared libraries must be constructed with
4954 a little care to make sure that the shared library is always
4955 available. This is especially important for packages whose
4956 shared libraries are vitally important, such as the C library
4957 (currently <tt>libc6</tt>).
4961 Packages involving shared libraries should be split up into
4962 several binary packages. This section mostly deals with how
4963 this separation is to be accomplished; rules for files within
4964 the shared library packages are in <ref id="libraries"> instead.
4967 <sect id="sharedlibs-runtime">
4968 <heading>Run-time shared libraries</heading>
4971 The run-time shared library needs to be placed in a package
4972 whose name changes whenever the shared object version
4975 Since it is common place to install several versions of a
4976 package that just provides shared libraries, it is a
4977 good idea that the library package should not
4978 contain any extraneous non-versioned files, unless they
4979 happen to be in versioned directories.</p>
4981 The most common mechanism is to place it in a package
4983 <package><var>libraryname</var><var>soversion</var></package>,
4984 where <file><var>soversion</var></file> is the version number
4985 in the soname of the shared library<footnote>
4986 The soname is the shared object name: it's the thing
4987 that has to match exactly between building an executable
4988 and running it for the dynamic linker to be able run the
4989 program. For example, if the soname of the library is
4990 <file>libfoo.so.6</file>, the library package would be
4991 called <file>libfoo6</file>.
4993 Alternatively, if it would be confusing to directly append
4994 <var>soversion</var> to <var>libraryname</var> (e.g. because
4995 <var>libraryname</var> itself ends in a number), you may use
4996 <package><var>libraryname</var>-<var>soversion</var></package> and
4997 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
5002 If you have several shared libraries built from the same
5003 source tree you may lump them all together into a single
5004 shared library package, provided that you change all of
5005 their sonames at once (so that you don't get filename
5006 clashes if you try to install different versions of the
5007 combined shared libraries package).
5011 The package should install the shared libraries under
5012 their normal names. For example, the <package>libgdbm3</package>
5013 package should install <file>libgdbm.so.3.0.0</file> as
5014 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
5015 renamed or re-linked by any <prgn>prerm</prgn> or
5016 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
5017 of renaming things safely without affecting running programs,
5018 and attempts to interfere with this are likely to lead to
5023 Shared libraries should not be installed executable, since
5024 the dynamic linker does not require this and trying to
5025 execute a shared library usually results in a core dump.
5029 The run-time library package should include the symbolic link that
5030 <prgn>ldconfig</prgn> would create for the shared libraries.
5031 For example, the <package>libgdbm3</package> package should include
5032 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
5033 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
5034 linker (for example <prgn>ld.so</prgn> or
5035 <prgn>ld-linux.so.*</prgn>) can find the library between the
5036 time that <prgn>dpkg</prgn> installs it and the time that
5037 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
5039 The package management system requires the library to be
5040 placed before the symbolic link pointing to it in the
5041 <file>.deb</file> file. This is so that when
5042 <prgn>dpkg</prgn> comes to install the symlink
5043 (overwriting the previous symlink pointing at an older
5044 version of the library), the new shared library is already
5045 in place. In the past, this was achieved by creating the
5046 library in the temporary packaging directory before
5047 creating the symlink. Unfortunately, this was not always
5048 effective, since the building of the tar file in the
5049 <file>.deb</file> depended on the behavior of the underlying
5050 file system. Some file systems (such as reiserfs) reorder
5051 the files so that the order of creation is forgotten.
5052 Since version 1.7.0, <prgn>dpkg</prgn>
5053 reorders the files itself as necessary when building a
5054 package. Thus it is no longer important to concern
5055 oneself with the order of file creation.
5059 <sect1 id="ldconfig">
5060 <heading><tt>ldconfig</tt></heading>
5063 Any package installing shared libraries in one of the default
5064 library directories of the dynamic linker (which are currently
5065 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
5066 listed in <file>/etc/ld.so.conf</file><footnote>
5068 <list compact="compact">
5069 <item>/usr/local/lib</item>
5070 <item>/usr/lib/libc5-compat</item>
5071 <item>/lib/libc5-compat</item>
5074 must use <prgn>ldconfig</prgn> to update the shared library
5079 The package maintainer scripts must only call
5080 <prgn>ldconfig</prgn> under these circumstances:
5081 <list compact="compact">
5082 <item>When the <prgn>postinst</prgn> script is run with a
5083 first argument of <tt>configure</tt>, the script must call
5084 <prgn>ldconfig</prgn>, and may optionally invoke
5085 <prgn>ldconfig</prgn> at other times.
5087 <item>When the <prgn>postrm</prgn> script is run with a
5088 first argument of <tt>remove</tt>, the script should call
5089 <prgn>ldconfig</prgn>.
5094 During install or upgrade, the preinst is called before
5095 the new files are installed, so calling "ldconfig" is
5096 pointless. The preinst of an existing package can also be
5097 called if an upgrade fails. However, this happens during
5098 the critical time when a shared libs may exist on-disk
5099 under a temporary name. Thus, it is dangerous and
5100 forbidden by current policy to call "ldconfig" at this
5105 When a package is installed or upgraded, "postinst
5106 configure" runs after the new files are safely on-disk.
5107 Since it is perfectly safe to invoke ldconfig
5108 unconditionally in a postinst, it is OK for a package to
5109 simply put ldconfig in its postinst without checking the
5110 argument. The postinst can also be called to recover from
5111 a failed upgrade. This happens before any new files are
5112 unpacked, so there is no reason to call "ldconfig" at this
5117 For a package that is being removed, prerm is
5118 called with all the files intact, so calling ldconfig is
5119 useless. The other calls to "prerm" happen in the case of
5120 upgrade at a time when all the files of the old package
5121 are on-disk, so again calling "ldconfig" is pointless.
5125 postrm, on the other hand, is called with the "remove"
5126 argument just after the files are removed, so this is
5127 the proper time to call "ldconfig" to notify the system
5128 of the fact that the shared libraries from the package
5129 are removed. The postrm can be called at several other
5130 times. At the time of "postrm purge", "postrm
5131 abort-install", or "postrm abort-upgrade", calling
5132 "ldconfig" is useless because the shared lib files are
5133 not on-disk. However, when "postrm" is invoked with
5134 arguments "upgrade", "failed-upgrade", or "disappear", a
5135 shared lib may exist on-disk under a temporary filename.
5143 <sect id="sharedlibs-support-files">
5144 <heading>Shared library support files</heading>
5147 If your package contains files whose names do not change with
5148 each change in the library shared object version, you must not
5149 put them in the shared library package. Otherwise, several
5150 versions of the shared library cannot be installed at the same
5151 time without filename clashes, making upgrades and transitions
5152 unnecessarily difficult.
5156 It is recommended that supporting files and run-time support
5157 programs that do not need to be invoked manually by users, but
5158 are nevertheless required for the package to function, be placed
5159 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
5160 preferably under <file>/usr/lib/</file><var>package-name</var>.
5161 If the program or file is architecture independent, the
5162 recommendation is for it to be placed in a subdirectory of
5163 <file>/usr/share</file> instead, preferably under
5164 <file>/usr/share/</file><var>package-name</var>. Following the
5165 <var>package-name</var> naming convention ensures that the file
5166 names change when the shared object version changes.
5170 Run-time support programs that use the shared library but are
5171 not required for the library to function or files used by the
5172 shared library that can be used by any version of the shared
5173 library package should instead be put in a separate package.
5174 This package might typically be named
5175 <package><var>libraryname</var>-tools</package>; note the
5176 absence of the <var>soversion</var> in the package name.
5180 Files and support programs only useful when compiling software
5181 against the library should be included in the development
5182 package for the library.<footnote>
5183 For example, a <file><var>package-name</var>-config</file>
5184 script or <package>pkg-config</package> configuration files.
5189 <sect id="sharedlibs-static">
5190 <heading>Static libraries</heading>
5193 The static library (<file><var>libraryname.a</var></file>)
5194 is usually provided in addition to the shared version.
5195 It is placed into the development package (see below).
5199 In some cases, it is acceptable for a library to be
5200 available in static form only; these cases include:
5202 <item>libraries for languages whose shared library support
5203 is immature or unstable</item>
5204 <item>libraries whose interfaces are in flux or under
5205 development (commonly the case when the library's
5206 major version number is zero, or where the ABI breaks
5207 across patchlevels)</item>
5208 <item>libraries which are explicitly intended to be
5209 available only in static form by their upstream
5214 <sect id="sharedlibs-dev">
5215 <heading>Development files</heading>
5218 If there are development files associated with a shared library,
5219 the source package needs to generate a binary development package
5220 named <package><var>libraryname</var><var>soversion</var>-dev</package>,
5221 or if you prefer only to support one development version at a
5222 time, <package><var>libraryname</var>-dev</package>. Installing
5223 the development package must result in installation of all the
5224 development files necessary for compiling programs against that
5225 shared library.<footnote>
5226 This wording allows the development files to be split into
5227 several packages, such as a separate architecture-independent
5228 <package><var>libraryname</var>-headers</package>, provided that
5229 the development package depends on all the required additional
5235 In case several development versions of a library exist, you may
5236 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5237 <ref id="conflicts">) to ensure that the user only installs one
5238 development version at a time (as different development versions are
5239 likely to have the same header files in them, which would cause a
5240 filename clash if both were installed).
5244 The development package should contain a symlink for the associated
5245 shared library without a version number. For example, the
5246 <package>libgdbm-dev</package> package should include a symlink
5247 from <file>/usr/lib/libgdbm.so</file> to
5248 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5249 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5250 <file>libgdbm.so</file> when compiling dynamically.
5254 <sect id="sharedlibs-intradeps">
5255 <heading>Dependencies between the packages of the same library</heading>
5258 Typically the development version should have an exact
5259 version dependency on the runtime library, to make sure that
5260 compilation and linking happens correctly. The
5261 <tt>${binary:Version}</tt> substitution variable can be
5262 useful for this purpose.
5264 Previously, <tt>${Source-Version}</tt> was used, but its name
5265 was confusing and it has been deprecated since dpkg 1.13.19.
5270 <sect id="sharedlibs-shlibdeps">
5271 <heading>Dependencies between the library and other packages -
5272 the <tt>shlibs</tt> system</heading>
5275 If a package contains a binary or library which links to a
5276 shared library, we must ensure that when the package is
5277 installed on the system, all of the libraries needed are
5278 also installed. This requirement led to the creation of the
5279 <tt>shlibs</tt> system, which is very simple in its design:
5280 any package which <em>provides</em> a shared library also
5281 provides information on the package dependencies required to
5282 ensure the presence of this library, and any package which
5283 <em>uses</em> a shared library uses this information to
5284 determine the dependencies it requires. The files which
5285 contain the mapping from shared libraries to the necessary
5286 dependency information are called <file>shlibs</file> files.
5290 Thus, when a package is built which contains any shared
5291 libraries, it must provide a <file>shlibs</file> file for other
5292 packages to use, and when a package is built which contains
5293 any shared libraries or compiled binaries, it must run
5294 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5295 on these to determine the libraries used and hence the
5296 dependencies needed by this package.<footnote>
5298 In the past, the shared libraries linked to were
5299 determined by calling <prgn>ldd</prgn>, but now
5300 <prgn>objdump</prgn> is used to do this. The only
5301 change this makes to package building is that
5302 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
5303 libraries, whereas in the past this was unnecessary.
5304 The rest of this footnote explains the advantage that
5309 We say that a binary <tt>foo</tt> <em>directly</em> uses
5310 a library <tt>libbar</tt> if it is explicitly linked
5311 with that library (that is, it uses the flag
5312 <tt>-lbar</tt> during the linking stage). Other
5313 libraries that are needed by <tt>libbar</tt> are linked
5314 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5315 linker will load them automatically when it loads
5316 <tt>libbar</tt>. A package should depend on
5317 the libraries it directly uses, and the dependencies for
5318 those libraries should automatically pull in the other
5323 Unfortunately, the <prgn>ldd</prgn> program shows both
5324 the directly and indirectly used libraries, meaning that
5325 the dependencies determined included both direct and
5326 indirect dependencies. The use of <prgn>objdump</prgn>
5327 avoids this problem by determining only the directly
5332 A good example of where this helps is the following. We
5333 could update <tt>libimlib</tt> with a new version that
5334 supports a new graphics format called dgf (but retaining
5335 the same major version number). If we used the old
5336 <prgn>ldd</prgn> method, every package that uses
5337 <tt>libimlib</tt> would need to be recompiled so it
5338 would also depend on <tt>libdgf</tt> or it wouldn't run
5339 due to missing symbols. However with the new system,
5340 packages using <tt>libimlib</tt> can rely on
5341 <tt>libimlib</tt> itself having the dependency on
5342 <tt>libdgf</tt> and so they would not need rebuilding.
5348 In the following sections, we will first describe where the
5349 various <tt>shlibs</tt> files are to be found, then how to
5350 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5351 file format and how to create them if your package contains a
5356 <heading>The <tt>shlibs</tt> files present on the system</heading>
5359 There are several places where <tt>shlibs</tt> files are
5360 found. The following list gives them in the order in which
5362 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5363 (The first one which gives the required information is used.)
5369 <p><file>debian/shlibs.local</file></p>
5372 This lists overrides for this package. Its use is
5373 described below (see <ref id="shlibslocal">).
5378 <p><file>/etc/dpkg/shlibs.override</file></p>
5381 This lists global overrides. This list is normally
5382 empty. It is maintained by the local system
5388 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5391 When packages are being built, any
5392 <file>debian/shlibs</file> files are copied into the
5393 control file area of the temporary build directory and
5394 given the name <file>shlibs</file>. These files give
5395 details of any shared libraries included in the
5397 An example may help here. Let us say that the
5398 source package <tt>foo</tt> generates two binary
5399 packages, <tt>libfoo2</tt> and
5400 <tt>foo-runtime</tt>. When building the binary
5401 packages, the two packages are created in the
5402 directories <file>debian/libfoo2</file> and
5403 <file>debian/foo-runtime</file> respectively.
5404 (<file>debian/tmp</file> could be used instead of one
5405 of these.) Since <tt>libfoo2</tt> provides the
5406 <tt>libfoo</tt> shared library, it will require a
5407 <tt>shlibs</tt> file, which will be installed in
5408 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
5410 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
5411 when <prgn>dpkg-shlibdeps</prgn> is run on the
5413 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
5415 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5416 determine whether <tt>foo-prog</tt>'s library
5417 dependencies are satisfied by any of the libraries
5418 provided by <tt>libfoo2</tt>. For this reason,
5419 <prgn>dpkg-shlibdeps</prgn> must only be run once
5420 all of the individual binary packages'
5421 <tt>shlibs</tt> files have been installed into the
5428 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5431 These are the <file>shlibs</file> files corresponding to
5432 all of the packages installed on the system, and are
5433 maintained by the relevant package maintainers.
5438 <p><file>/etc/dpkg/shlibs.default</file></p>
5441 This file lists any shared libraries whose packages
5442 have failed to provide correct <file>shlibs</file> files.
5443 It was used when the <file>shlibs</file> setup was first
5444 introduced, but it is now normally empty. It is
5445 maintained by the <tt>dpkg</tt> maintainer.
5453 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5454 <file>shlibs</file> files</heading>
5458 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5459 into your <file>debian/rules</file> file. If your package
5460 contains only compiled binaries and libraries (but no scripts),
5461 you can use a command such as:
5462 <example compact="compact">
5463 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5464 debian/tmp/usr/lib/*
5466 Otherwise, you will need to explicitly list the compiled
5467 binaries and libraries.<footnote>
5468 If you are using <tt>debhelper</tt>, the
5469 <prgn>dh_shlibdeps</prgn> program will do this work for
5470 you. It will also correctly handle multi-binary
5476 This command puts the dependency information into the
5477 <file>debian/substvars</file> file, which is then used by
5478 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5479 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5480 field in the control file for this to work.
5484 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
5485 done. If it does complain you might need to create your own
5486 <file>debian/shlibs.local</file> file, as explained below (see
5487 <ref id="shlibslocal">).
5491 If you have multiple binary packages, you will need to call
5492 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5493 compiled libraries or binaries. In such a case, you will
5494 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5495 utilities to specify a different <file>substvars</file> file.
5499 If you are creating a udeb for use in the Debian Installer,
5500 you will need to specify that <prgn>dpkg-shlibdeps</prgn>
5501 should use the dependency line of type <tt>udeb</tt> by
5502 adding the <tt>-tudeb</tt> option<footnote>
5503 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5504 will automatically add this option if it knows it is
5506 </footnote>. If there is no dependency line of type <tt>udeb</tt>
5507 in the <file>shlibs</file> file, <prgn>dpkg-shlibdeps</prgn> will
5508 fall back to the regular dependency line.
5512 For more details on dpkg-shlibdeps, please see
5513 <ref id="pkg-dpkg-shlibdeps"> and
5514 <manref name="dpkg-shlibdeps" section="1">.
5519 <heading>The <file>shlibs</file> File Format</heading>
5522 Each <file>shlibs</file> file has the same format. Lines
5523 beginning with <tt>#</tt> are considered to be comments and
5524 are ignored. Each line is of the form:
5525 <example compact="compact">
5526 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5531 We will explain this by reference to the example of the
5532 <tt>zlib1g</tt> package, which (at the time of writing)
5533 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5537 <var>type</var> is an optional element that indicates the type
5538 of package for which the line is valid. The only type currently
5539 in use is <tt>udeb</tt>. The colon and space after the type are
5544 <var>library-name</var> is the name of the shared library,
5545 in this case <tt>libz</tt>. (This must match the name part
5546 of the soname, see below.)
5550 <var>soname-version</var> is the version part of the soname of
5551 the library. The soname is the thing that must exactly match
5552 for the library to be recognized by the dynamic linker, and is
5554 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5555 example, <tt>libz.so.1</tt>.<footnote>
5556 This can be determined using the command
5557 <example compact="compact">
5558 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5561 The version part is the part which comes after
5562 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
5566 <var>dependencies</var> has the same syntax as a dependency
5567 field in a binary package control file. It should give
5568 details of which packages are required to satisfy a binary
5569 built against the version of the library contained in the
5570 package. See <ref id="depsyntax"> for details.
5574 In our example, if the first version of the <tt>zlib1g</tt>
5575 package which contained a minor number of at least
5576 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5577 <tt>shlibs</tt> entry for this library could say:
5578 <example compact="compact">
5579 libz 1 zlib1g (>= 1:1.1.3)
5581 The version-specific dependency is to avoid warnings from
5582 the dynamic linker about using older shared libraries with
5587 As zlib1g also provides a udeb containing the shared library,
5588 there would also be a second line:
5589 <example compact="compact">
5590 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5596 <heading>Providing a <file>shlibs</file> file</heading>
5599 If your package provides a shared library, you need to create
5600 a <file>shlibs</file> file following the format described above.
5601 It is usual to call this file <file>debian/shlibs</file> (but if
5602 you have multiple binary packages, you might want to call it
5603 <file>debian/shlibs.<var>package</var></file> instead). Then
5604 let <file>debian/rules</file> install it in the control area:
5605 <example compact="compact">
5606 install -m644 debian/shlibs debian/tmp/DEBIAN
5608 or, in the case of a multi-binary package:
5609 <example compact="compact">
5610 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5612 An alternative way of doing this is to create the
5613 <file>shlibs</file> file in the control area directly from
5614 <file>debian/rules</file> without using a <file>debian/shlibs</file>
5615 file at all,<footnote>
5616 This is what <prgn>dh_makeshlibs</prgn> in the
5617 <tt>debhelper</tt> suite does. If your package also has a udeb
5618 that provides a shared library, <prgn>dh_makeshlibs</prgn> can
5619 automatically generate the <tt>udeb:</tt> lines if you specify
5620 the name of the udeb with the <tt>--add-udeb</tt> option.
5622 since the <file>debian/shlibs</file> file itself is ignored by
5623 <prgn>dpkg-shlibdeps</prgn>.
5627 As <prgn>dpkg-shlibdeps</prgn> reads the
5628 <file>DEBIAN/shlibs</file> files in all of the binary packages
5629 being built from this source package, all of the
5630 <file>DEBIAN/shlibs</file> files should be installed before
5631 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5636 <sect1 id="shlibslocal">
5637 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
5640 This file is intended only as a <em>temporary</em> fix if
5641 your binaries or libraries depend on a library whose package
5642 does not yet provide a correct <file>shlibs</file> file.
5646 We will assume that you are trying to package a binary
5647 <tt>foo</tt>. When you try running
5648 <prgn>dpkg-shlibdeps</prgn> you get the following error
5649 message (<tt>-O</tt> displays the dependency information on
5650 <tt>stdout</tt> instead of writing it to
5651 <tt>debian/substvars</tt>, and the lines have been wrapped
5652 for ease of reading):
5653 <example compact="compact">
5654 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
5655 dpkg-shlibdeps: warning: unable to find dependency
5656 information for shared library libbar (soname 1,
5657 path /usr/lib/libbar.so.1, dependency field Depends)
5658 shlibs:Depends=libc6 (>= 2.2.2-2)
5660 You can then run <prgn>ldd</prgn> on the binary to find the
5661 full location of the library concerned:
5662 <example compact="compact">
5664 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5665 libc.so.6 => /lib/libc.so.6 (0x40032000)
5666 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5668 So the <prgn>foo</prgn> binary depends on the
5669 <prgn>libbar</prgn> shared library, but no package seems to
5670 provide a <file>*.shlibs</file> file handling
5671 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5672 determine the package responsible:
5673 <example compact="compact">
5674 $ dpkg -S /usr/lib/libbar.so.1
5675 bar1: /usr/lib/libbar.so.1
5676 $ dpkg -s bar1 | grep Version
5679 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5680 is the one we are using. Now we can file a bug against the
5681 <tt>bar1</tt> package and create our own
5682 <file>debian/shlibs.local</file> to locally fix the problem.
5683 Including the following line into your
5684 <file>debian/shlibs.local</file> file:
5685 <example compact="compact">
5686 libbar 1 bar1 (>= 1.0-1)
5688 should allow the package build to work.
5692 As soon as the maintainer of <tt>bar1</tt> provides a
5693 correct <file>shlibs</file> file, you should remove this line
5694 from your <file>debian/shlibs.local</file> file. (You should
5695 probably also then have a versioned <tt>Build-Depends</tt>
5696 on <tt>bar1</tt> to help ensure that others do not have the
5697 same problem building your package.)
5706 <chapt id="opersys"><heading>The Operating System</heading>
5709 <heading>File system hierarchy</heading>
5713 <heading>File System Structure</heading>
5716 The location of all installed files and directories must
5717 comply with the Filesystem Hierarchy Standard (FHS),
5718 version 2.3, with the exceptions noted below, and except
5719 where doing so would violate other terms of Debian
5720 Policy. The following exceptions to the FHS apply:
5725 The optional rules related to user specific
5726 configuration files for applications are stored in
5727 the user's home directory are relaxed. It is
5728 recommended that such files start with the
5729 '<tt>.</tt>' character (a "dot file"), and if an
5730 application needs to create more than one dot file
5731 then the preferred placement is in a subdirectory
5732 with a name starting with a '.' character, (a "dot
5733 directory"). In this case it is recommended the
5734 configuration files not start with the '.'
5740 The requirement for amd64 to use <file>/lib64</file>
5741 for 64 bit binaries is removed.
5746 The requirement for object files, internal binaries, and
5747 libraries, including <file>libc.so.*</file>, to be located
5748 directly under <file>/lib{,32}</file> and
5749 <file>/usr/lib{,32}</file> is amended, permitting files
5750 to instead be installed to
5751 <file>/lib/<var>triplet</var></file> and
5752 <file>/usr/lib/<var>triplet</var></file>, where
5753 <tt><var>triplet</var></tt> is the value returned by
5754 <tt>dpkg-architecture -qDEB_HOST_GNU_TYPE</tt> for the
5755 architecture of the package. Packages may <em>not</em>
5756 install files to any <var>triplet</var> path other
5757 than the one matching the architecture of that package;
5758 for instance, an <tt>Architecture: amd64</tt> package
5759 containing 32-bit x86 libraries may not install these
5760 libraries to <file>/usr/lib/i486-linux-gnu</file>.
5762 This is necessary in order to reserve the directories for
5763 use in cross-installation of library packages from other
5764 architectures, as part of the planned deployment of
5769 Applications may also use a single subdirectory under
5770 <file>/usr/lib/<var>triplet</var></file>.
5773 The execution time linker/loader, ld*, must still be made
5774 available in the existing location under /lib or /lib64
5775 since this is part of the ELF ABI for the architecture.
5780 The requirement that
5781 <file>/usr/local/share/man</file> be "synonymous"
5782 with <file>/usr/local/man</file> is relaxed to a
5787 The requirement that windowmanagers with a single
5788 configuration file call it <file>system.*wmrc</file>
5789 is removed, as is the restriction that the window
5790 manager subdirectory be named identically to the
5791 window manager name itself.
5796 The requirement that boot manager configuration
5797 files live in <file>/etc</file>, or at least are
5798 symlinked there, is relaxed to a recommendation.
5803 The following directories in the root filesystem are
5804 additionally allowed: <file>/sys</file> and
5805 <file>/selinux</file>. <footnote>These directories
5806 are used as mount points to mount virtual filesystems
5807 to get access to kernel information.</footnote>
5814 The version of this document referred here can be
5815 found in the <tt>debian-policy</tt> package or on <url
5816 id="http://www.debian.org/doc/packaging-manuals/fhs/"
5817 name="FHS (Debian copy)"> alongside this manual (or, if
5818 you have the <package>debian-policy</package> installed,
5820 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5821 (local copy)">). The
5822 latest version, which may be a more recent version, may
5824 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5825 Specific questions about following the standard may be
5826 asked on the <tt>debian-devel</tt> mailing list, or
5827 referred to the FHS mailing list (see the
5828 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5834 <heading>Site-specific programs</heading>
5837 As mandated by the FHS, packages must not place any
5838 files in <file>/usr/local</file>, either by putting them in
5839 the file system archive to be unpacked by <prgn>dpkg</prgn>
5840 or by manipulating them in their maintainer scripts.
5844 However, the package may create empty directories below
5845 <file>/usr/local</file> so that the system administrator knows
5846 where to place site-specific files. These are not
5847 directories <em>in</em> <file>/usr/local</file>, but are
5848 children of directories in <file>/usr/local</file>. These
5849 directories (<file>/usr/local/*/dir/</file>)
5850 should be removed on package removal if they are
5855 Note that this applies only to
5856 directories <em>below</em> <file>/usr/local</file>,
5857 not <em>in</em> <file>/usr/local</file>. Packages must
5858 not create sub-directories in the
5859 directory <file>/usr/local</file> itself, except those
5860 listed in FHS, section 4.5. However, you may create
5861 directories below them as you wish. You must not remove
5862 any of the directories listed in 4.5, even if you created
5867 Since <file>/usr/local</file> can be mounted read-only from a
5868 remote server, these directories must be created and
5869 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5870 maintainer scripts and not be included in the
5871 <file>.deb</file> archive. These scripts must not fail if
5872 either of these operations fail.
5876 For example, the <tt>emacsen-common</tt> package could
5877 contain something like
5878 <example compact="compact">
5879 if [ ! -e /usr/local/share/emacs ]
5881 if mkdir /usr/local/share/emacs 2>/dev/null
5883 chown root:staff /usr/local/share/emacs
5884 chmod 2775 /usr/local/share/emacs
5888 in its <prgn>postinst</prgn> script, and
5889 <example compact="compact">
5890 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5891 rmdir /usr/local/share/emacs 2>/dev/null || true
5893 in the <prgn>prerm</prgn> script. (Note that this form is
5894 used to ensure that if the script is interrupted, the
5895 directory <file>/usr/local/share/emacs</file> will still be
5900 If you do create a directory in <file>/usr/local</file> for
5901 local additions to a package, you should ensure that
5902 settings in <file>/usr/local</file> take precedence over the
5903 equivalents in <file>/usr</file>.
5907 However, because <file>/usr/local</file> and its contents are
5908 for exclusive use of the local administrator, a package
5909 must not rely on the presence or absence of files or
5910 directories in <file>/usr/local</file> for normal operation.
5914 The <file>/usr/local</file> directory itself and all the
5915 subdirectories created by the package should (by default) have
5916 permissions 2775 (group-writable and set-group-id) and be
5917 owned by <tt>root:staff</tt>.
5922 <heading>The system-wide mail directory</heading>
5924 The system-wide mail directory
5925 is <file>/var/mail</file>. This directory is part of the
5926 base system and should not be owned by any particular mail
5927 agents. The use of the old
5928 location <file>/var/spool/mail</file> is deprecated, even
5929 though the spool may still be physically located there.
5935 <heading>Users and groups</heading>
5938 <heading>Introduction</heading>
5940 The Debian system can be configured to use either plain or
5945 Some user ids (UIDs) and group ids (GIDs) are reserved
5946 globally for use by certain packages. Because some
5947 packages need to include files which are owned by these
5948 users or groups, or need the ids compiled into binaries,
5949 these ids must be used on any Debian system only for the
5950 purpose for which they are allocated. This is a serious
5951 restriction, and we should avoid getting in the way of
5952 local administration policies. In particular, many sites
5953 allocate users and/or local system groups starting at 100.
5957 Apart from this we should have dynamically allocated ids,
5958 which should by default be arranged in some sensible
5959 order, but the behavior should be configurable.
5963 Packages other than <tt>base-passwd</tt> must not modify
5964 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5965 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5970 <heading>UID and GID classes</heading>
5972 The UID and GID numbers are divided into classes as
5978 Globally allocated by the Debian project, the same
5979 on every Debian system. These ids will appear in
5980 the <file>passwd</file> and <file>group</file> files of all
5981 Debian systems, new ids in this range being added
5982 automatically as the <tt>base-passwd</tt> package is
5987 Packages which need a single statically allocated
5988 uid or gid should use one of these; their
5989 maintainers should ask the <tt>base-passwd</tt>
5997 Dynamically allocated system users and groups.
5998 Packages which need a user or group, but can have
5999 this user or group allocated dynamically and
6000 differently on each system, should use <tt>adduser
6001 --system</tt> to create the group and/or user.
6002 <prgn>adduser</prgn> will check for the existence of
6003 the user or group, and if necessary choose an unused
6004 id based on the ranges specified in
6005 <file>adduser.conf</file>.
6009 <tag>1000-59999:</tag>
6012 Dynamically allocated user accounts. By default
6013 <prgn>adduser</prgn> will choose UIDs and GIDs for
6014 user accounts in this range, though
6015 <file>adduser.conf</file> may be used to modify this
6020 <tag>60000-64999:</tag>
6023 Globally allocated by the Debian project, but only
6024 created on demand. The ids are allocated centrally
6025 and statically, but the actual accounts are only
6026 created on users' systems on demand.
6030 These ids are for packages which are obscure or
6031 which require many statically-allocated ids. These
6032 packages should check for and create the accounts in
6033 <file>/etc/passwd</file> or <file>/etc/group</file> (using
6034 <prgn>adduser</prgn> if it has this facility) if
6035 necessary. Packages which are likely to require
6036 further allocations should have a "hole" left after
6037 them in the allocation, to give them room to
6042 <tag>65000-65533:</tag>
6050 User <tt>nobody</tt>. The corresponding gid refers
6051 to the group <tt>nogroup</tt>.
6058 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
6059 not</em> be used, because it is the error return
6068 <sect id="sysvinit">
6069 <heading>System run levels and <file>init.d</file> scripts</heading>
6071 <sect1 id="/etc/init.d">
6072 <heading>Introduction</heading>
6075 The <file>/etc/init.d</file> directory contains the scripts
6076 executed by <prgn>init</prgn> at boot time and when the
6077 init state (or "runlevel") is changed (see <manref
6078 name="init" section="8">).
6082 There are at least two different, yet functionally
6083 equivalent, ways of handling these scripts. For the sake
6084 of simplicity, this document describes only the symbolic
6085 link method. However, it must not be assumed by maintainer
6086 scripts that this method is being used, and any automated
6087 manipulation of the various runlevel behaviors by
6088 maintainer scripts must be performed using
6089 <prgn>update-rc.d</prgn> as described below and not by
6090 manually installing or removing symlinks. For information
6091 on the implementation details of the other method,
6092 implemented in the <tt>file-rc</tt> package, please refer
6093 to the documentation of that package.
6097 These scripts are referenced by symbolic links in the
6098 <file>/etc/rc<var>n</var>.d</file> directories. When changing
6099 runlevels, <prgn>init</prgn> looks in the directory
6100 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
6101 execute, where <tt><var>n</var></tt> is the runlevel that
6102 is being changed to, or <tt>S</tt> for the boot-up
6107 The names of the links all have the form
6108 <file>S<var>mm</var><var>script</var></file> or
6109 <file>K<var>mm</var><var>script</var></file> where
6110 <var>mm</var> is a two-digit number and <var>script</var>
6111 is the name of the script (this should be the same as the
6112 name of the actual script in <file>/etc/init.d</file>).
6116 When <prgn>init</prgn> changes runlevel first the targets
6117 of the links whose names start with a <tt>K</tt> are
6118 executed, each with the single argument <tt>stop</tt>,
6119 followed by the scripts prefixed with an <tt>S</tt>, each
6120 with the single argument <tt>start</tt>. (The links are
6121 those in the <file>/etc/rc<var>n</var>.d</file> directory
6122 corresponding to the new runlevel.) The <tt>K</tt> links
6123 are responsible for killing services and the <tt>S</tt>
6124 link for starting services upon entering the runlevel.
6128 For example, if we are changing from runlevel 2 to
6129 runlevel 3, init will first execute all of the <tt>K</tt>
6130 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
6131 all of the <tt>S</tt> prefixed scripts in that directory.
6132 The links starting with <tt>K</tt> will cause the
6133 referred-to file to be executed with an argument of
6134 <tt>stop</tt>, and the <tt>S</tt> links with an argument
6139 The two-digit number <var>mm</var> is used to determine
6140 the order in which to run the scripts: low-numbered links
6141 have their scripts run first. For example, the
6142 <tt>K20</tt> scripts will be executed before the
6143 <tt>K30</tt> scripts. This is used when a certain service
6144 must be started before another. For example, the name
6145 server <prgn>bind</prgn> might need to be started before
6146 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
6147 can set up its access lists. In this case, the script
6148 that starts <prgn>bind</prgn> would have a lower number
6149 than the script that starts <prgn>inn</prgn> so that it
6151 <example compact="compact">
6158 The two runlevels 0 (halt) and 6 (reboot) are slightly
6159 different. In these runlevels, the links with an
6160 <tt>S</tt> prefix are still called after those with a
6161 <tt>K</tt> prefix, but they too are called with the single
6162 argument <tt>stop</tt>.
6166 <sect1 id="writing-init">
6167 <heading>Writing the scripts</heading>
6170 Packages that include daemons for system services should
6171 place scripts in <file>/etc/init.d</file> to start or stop
6172 services at boot time or during a change of runlevel.
6173 These scripts should be named
6174 <file>/etc/init.d/<var>package</var></file>, and they should
6175 accept one argument, saying what to do:
6178 <tag><tt>start</tt></tag>
6179 <item>start the service,</item>
6181 <tag><tt>stop</tt></tag>
6182 <item>stop the service,</item>
6184 <tag><tt>restart</tt></tag>
6185 <item>stop and restart the service if it's already running,
6186 otherwise start the service</item>
6188 <tag><tt>reload</tt></tag>
6189 <item><p>cause the configuration of the service to be
6190 reloaded without actually stopping and restarting
6193 <tag><tt>force-reload</tt></tag>
6194 <item>cause the configuration to be reloaded if the
6195 service supports this, otherwise restart the
6199 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
6200 <tt>force-reload</tt> options should be supported by all
6201 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
6206 The <file>init.d</file> scripts must ensure that they will
6207 behave sensibly (i.e., returning success and not starting
6208 multiple copies of a service) if invoked with <tt>start</tt>
6209 when the service is already running, or with <tt>stop</tt>
6210 when it isn't, and that they don't kill unfortunately-named
6211 user processes. The best way to achieve this is usually to
6212 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
6217 Be careful of using <tt>set -e</tt> in <file>init.d</file>
6218 scripts. Writing correct <file>init.d</file> scripts requires
6219 accepting various error exit statuses when daemons are already
6220 running or already stopped without aborting
6221 the <file>init.d</file> script, and common <file>init.d</file>
6222 function libraries are not safe to call with <tt>set -e</tt>
6224 <tt>/lib/lsb/init-functions</tt>, which assists in writing
6225 LSB-compliant init scripts, may fail if <tt>set -e</tt> is
6226 in effect and echoing status messages to the console fails,
6228 </footnote>. For <tt>init.d</tt> scripts, it's often easier
6229 to not use <tt>set -e</tt> and instead check the result of
6230 each command separately.
6234 If a service reloads its configuration automatically (as
6235 in the case of <prgn>cron</prgn>, for example), the
6236 <tt>reload</tt> option of the <file>init.d</file> script
6237 should behave as if the configuration has been reloaded
6242 The <file>/etc/init.d</file> scripts must be treated as
6243 configuration files, either (if they are present in the
6244 package, that is, in the .deb file) by marking them as
6245 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
6246 by managing them correctly in the maintainer scripts (see
6247 <ref id="config-files">). This is important since we want
6248 to give the local system administrator the chance to adapt
6249 the scripts to the local system, e.g., to disable a
6250 service without de-installing the package, or to specify
6251 some special command line options when starting a service,
6252 while making sure their changes aren't lost during the next
6257 These scripts should not fail obscurely when the
6258 configuration files remain but the package has been
6259 removed, as configuration files remain on the system after
6260 the package has been removed. Only when <prgn>dpkg</prgn>
6261 is executed with the <tt>--purge</tt> option will
6262 configuration files be removed. In particular, as the
6263 <file>/etc/init.d/<var>package</var></file> script itself is
6264 usually a <tt>conffile</tt>, it will remain on the system
6265 if the package is removed but not purged. Therefore, you
6266 should include a <tt>test</tt> statement at the top of the
6268 <example compact="compact">
6269 test -f <var>program-executed-later-in-script</var> || exit 0
6274 Often there are some variables in the <file>init.d</file>
6275 scripts whose values control the behavior of the scripts,
6276 and which a system administrator is likely to want to
6277 change. As the scripts themselves are frequently
6278 <tt>conffile</tt>s, modifying them requires that the
6279 administrator merge in their changes each time the package
6280 is upgraded and the <tt>conffile</tt> changes. To ease
6281 the burden on the system administrator, such configurable
6282 values should not be placed directly in the script.
6283 Instead, they should be placed in a file in
6284 <file>/etc/default</file>, which typically will have the same
6285 base name as the <file>init.d</file> script. This extra file
6286 should be sourced by the script when the script runs. It
6287 must contain only variable settings and comments in SUSv3
6288 <prgn>sh</prgn> format. It may either be a
6289 <tt>conffile</tt> or a configuration file maintained by
6290 the package maintainer scripts. See <ref id="config-files">
6295 To ensure that vital configurable values are always
6296 available, the <file>init.d</file> script should set default
6297 values for each of the shell variables it uses, either
6298 before sourcing the <file>/etc/default/</file> file or
6299 afterwards using something like the <tt>:
6300 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6301 script must behave sensibly and not fail if the
6302 <file>/etc/default</file> file is deleted.
6306 <file>/var/run</file> and <file>/var/lock</file> may be mounted
6307 as temporary filesystems<footnote>
6308 For example, using the <tt>RAMRUN</tt> and <tt>RAMLOCK</tt>
6309 options in <file>/etc/default/rcS</file>.
6310 </footnote>, so the <file>init.d</file> scripts must handle this
6311 correctly. This will typically amount to creating any required
6312 subdirectories dynamically when the <file>init.d</file> script
6313 is run, rather than including them in the package and relying on
6314 <prgn>dpkg</prgn> to create them.
6319 <heading>Interfacing with the initscript system</heading>
6322 Maintainers should use the abstraction layer provided by
6323 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6324 programs to deal with initscripts in their packages'
6325 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6326 and <prgn>postrm</prgn>.
6330 Directly managing the /etc/rc?.d links and directly
6331 invoking the <file>/etc/init.d/</file> initscripts should
6332 be done only by packages providing the initscript
6333 subsystem (such as <prgn>sysv-rc</prgn> and
6334 <prgn>file-rc</prgn>).
6338 <heading>Managing the links</heading>
6341 The program <prgn>update-rc.d</prgn> is provided for
6342 package maintainers to arrange for the proper creation and
6343 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6344 or their functional equivalent if another method is being
6345 used. This may be used by maintainers in their packages'
6346 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6350 You must not include any <file>/etc/rc<var>n</var>.d</file>
6351 symbolic links in the actual archive or manually create or
6352 remove the symbolic links in maintainer scripts; you must
6353 use the <prgn>update-rc.d</prgn> program instead. (The
6354 former will fail if an alternative method of maintaining
6355 runlevel information is being used.) You must not include
6356 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6357 in the archive either. (Only the <tt>sysvinit</tt>
6362 By default <prgn>update-rc.d</prgn> will start services in
6363 each of the multi-user state runlevels (2, 3, 4, and 5)
6364 and stop them in the halt runlevel (0), the single-user
6365 runlevel (1) and the reboot runlevel (6). The system
6366 administrator will have the opportunity to customize
6367 runlevels by simply adding, moving, or removing the
6368 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6369 symbolic links are being used, or by modifying
6370 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6375 To get the default behavior for your package, put in your
6376 <prgn>postinst</prgn> script
6377 <example compact="compact">
6378 update-rc.d <var>package</var> defaults
6380 and in your <prgn>postrm</prgn>
6381 <example compact="compact">
6382 if [ "$1" = purge ]; then
6383 update-rc.d <var>package</var> remove
6385 </example>. Note that if your package changes runlevels
6386 or priority, you may have to remove and recreate the links,
6387 since otherwise the old links may persist. Refer to the
6388 documentation of <prgn>update-rc.d</prgn>.
6392 This will use a default sequence number of 20. If it does
6393 not matter when or in which order the <file>init.d</file>
6394 script is run, use this default. If it does, then you
6395 should talk to the maintainer of the <prgn>sysvinit</prgn>
6396 package or post to <tt>debian-devel</tt>, and they will
6397 help you choose a number.
6401 For more information about using <tt>update-rc.d</tt>,
6402 please consult its man page <manref name="update-rc.d"
6408 <heading>Running initscripts</heading>
6410 The program <prgn>invoke-rc.d</prgn> is provided to make
6411 it easier for package maintainers to properly invoke an
6412 initscript, obeying runlevel and other locally-defined
6413 constraints that might limit a package's right to start,
6414 stop and otherwise manage services. This program may be
6415 used by maintainers in their packages' scripts.
6419 The package maintainer scripts must use
6420 <prgn>invoke-rc.d</prgn> to invoke the
6421 <file>/etc/init.d/*</file> initscripts, instead of
6422 calling them directly.
6426 By default, <prgn>invoke-rc.d</prgn> will pass any
6427 action requests (start, stop, reload, restart...) to the
6428 <file>/etc/init.d</file> script, filtering out requests
6429 to start or restart a service out of its intended
6434 Most packages will simply need to change:
6435 <example compact="compact">/etc/init.d/<package>
6436 <action></example> in their <prgn>postinst</prgn>
6437 and <prgn>prerm</prgn> scripts to:
6438 <example compact="compact">
6439 if which invoke-rc.d >/dev/null 2>&1; then
6440 invoke-rc.d <var>package</var> <action>
6442 /etc/init.d/<var>package</var> <action>
6448 A package should register its initscript services using
6449 <prgn>update-rc.d</prgn> before it tries to invoke them
6450 using <prgn>invoke-rc.d</prgn>. Invocation of
6451 unregistered services may fail.
6455 For more information about using
6456 <prgn>invoke-rc.d</prgn>, please consult its man page
6457 <manref name="invoke-rc.d" section="8">.
6463 <heading>Boot-time initialization</heading>
6466 There used to be another directory, <file>/etc/rc.boot</file>,
6467 which contained scripts which were run once per machine
6468 boot. This has been deprecated in favour of links from
6469 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6470 described in <ref id="/etc/init.d">. Packages must not
6471 place files in <file>/etc/rc.boot</file>.
6476 <heading>Example</heading>
6479 An example on which you can base your
6480 <file>/etc/init.d</file> scripts is found in
6481 <file>/etc/init.d/skeleton</file>.
6488 <heading>Console messages from <file>init.d</file> scripts</heading>
6491 This section describes the formats to be used for messages
6492 written to standard output by the <file>/etc/init.d</file>
6493 scripts. The intent is to improve the consistency of
6494 Debian's startup and shutdown look and feel. For this
6495 reason, please look very carefully at the details. We want
6496 the messages to have the same format in terms of wording,
6497 spaces, punctuation and case of letters.
6501 Here is a list of overall rules that should be used for
6502 messages generated by <file>/etc/init.d</file> scripts.
6508 The message should fit in one line (fewer than 80
6509 characters), start with a capital letter and end with
6510 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6514 If the script is performing some time consuming task in
6515 the background (not merely starting or stopping a
6516 program, for instance), an ellipsis (three dots:
6517 <tt>...</tt>) should be output to the screen, with no
6518 leading or tailing whitespace or line feeds.
6522 The messages should appear as if the computer is telling
6523 the user what it is doing (politely :-), but should not
6524 mention "it" directly. For example, instead of:
6525 <example compact="compact">
6526 I'm starting network daemons: nfsd mountd.
6528 the message should say
6529 <example compact="compact">
6530 Starting network daemons: nfsd mountd.
6537 <tt>init.d</tt> script should use the following standard
6538 message formats for the situations enumerated below.
6544 <p>When daemons are started</p>
6547 If the script starts one or more daemons, the output
6548 should look like this (a single line, no leading
6550 <example compact="compact">
6551 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6553 The <var>description</var> should describe the
6554 subsystem the daemon or set of daemons are part of,
6555 while <var>daemon-1</var> up to <var>daemon-n</var>
6556 denote each daemon's name (typically the file name of
6561 For example, the output of <file>/etc/init.d/lpd</file>
6563 <example compact="compact">
6564 Starting printer spooler: lpd.
6569 This can be achieved by saying
6570 <example compact="compact">
6571 echo -n "Starting printer spooler: lpd"
6572 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6575 in the script. If there are more than one daemon to
6576 start, the output should look like this:
6577 <example compact="compact">
6578 echo -n "Starting remote file system services:"
6579 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6580 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6581 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6584 This makes it possible for the user to see what is
6585 happening and when the final daemon has been started.
6586 Care should be taken in the placement of white spaces:
6587 in the example above the system administrators can
6588 easily comment out a line if they don't want to start
6589 a specific daemon, while the displayed message still
6595 <p>When a system parameter is being set</p>
6598 If you have to set up different system parameters
6599 during the system boot, you should use this format:
6600 <example compact="compact">
6601 Setting <var>parameter</var> to "<var>value</var>".
6606 You can use a statement such as the following to get
6608 <example compact="compact">
6609 echo "Setting DNS domainname to \"$domainname\"."
6614 Note that the same symbol (<tt>"</tt>) <!-- " --> is used
6615 for the left and right quotation marks. A grave accent
6616 (<tt>`</tt>) is not a quote character; neither is an
6617 apostrophe (<tt>'</tt>).
6622 <p>When a daemon is stopped or restarted</p>
6625 When you stop or restart a daemon, you should issue a
6626 message identical to the startup message, except that
6627 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6628 or <tt>Restarting</tt> respectively.
6632 For example, stopping the printer daemon will look like
6634 <example compact="compact">
6635 Stopping printer spooler: lpd.
6641 <p>When something is executed</p>
6644 There are several examples where you have to run a
6645 program at system startup or shutdown to perform a
6646 specific task, for example, setting the system's clock
6647 using <prgn>netdate</prgn> or killing all processes
6648 when the system shuts down. Your message should look
6650 <example compact="compact">
6651 Doing something very useful...done.
6653 You should print the <tt>done.</tt> immediately after
6654 the job has been completed, so that the user is
6655 informed why they have to wait. You can get this
6657 <example compact="compact">
6658 echo -n "Doing something very useful..."
6667 <p>When the configuration is reloaded</p>
6670 When a daemon is forced to reload its configuration
6671 files you should use the following format:
6672 <example compact="compact">
6673 Reloading <var>description</var> configuration...done.
6675 where <var>description</var> is the same as in the
6676 daemon starting message.
6684 <heading>Cron jobs</heading>
6687 Packages must not modify the configuration file
6688 <file>/etc/crontab</file>, and they must not modify the files in
6689 <file>/var/spool/cron/crontabs</file>.</p>
6692 If a package wants to install a job that has to be executed
6693 via cron, it should place a file with the name of the
6694 package in one or more of the following directories:
6695 <example compact="compact">
6701 As these directory names imply, the files within them are
6702 executed on an hourly, daily, weekly, or monthly basis,
6703 respectively. The exact times are listed in
6704 <file>/etc/crontab</file>.</p>
6707 All files installed in any of these directories must be
6708 scripts (e.g., shell scripts or Perl scripts) so that they
6709 can easily be modified by the local system administrator.
6710 In addition, they must be treated as configuration files.
6714 If a certain job has to be executed at some other frequency or
6715 at a specific time, the package should install a file
6716 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6717 same syntax as <file>/etc/crontab</file> and is processed by
6718 <prgn>cron</prgn> automatically. The file must also be
6719 treated as a configuration file. (Note that entries in the
6720 <file>/etc/cron.d</file> directory are not handled by
6721 <prgn>anacron</prgn>. Thus, you should only use this
6722 directory for jobs which may be skipped if the system is not
6725 Unlike <file>crontab</file> files described in the IEEE Std
6726 1003.1-2008 (POSIX.1) available from
6727 <url id="http://www.opengroup.org/onlinepubs/9699919799/"
6728 name="The Open Group">, the files in
6729 <file>/etc/cron.d</file> and the file
6730 <file>/etc/crontab</file> have seven fields; namely:
6732 <item>Minute [0,59]</item>
6733 <item>Hour [0,23]</item>
6734 <item>Day of the month [1,31]</item>
6735 <item>Month of the year [1,12]</item>
6736 <item>Day of the week ([0,6] with 0=Sunday)</item>
6737 <item>Username</item>
6738 <item>Command to be run</item>
6740 Ranges of numbers are allowed. Ranges are two numbers
6741 separated with a hyphen. The specified range is inclusive.
6742 Lists are allowed. A list is a set of numbers (or ranges)
6743 separated by commas. Step values can be used in conjunction
6748 The scripts or <tt>crontab</tt> entries in these directories should
6749 check if all necessary programs are installed before they
6750 try to execute them. Otherwise, problems will arise when a
6751 package was removed but not purged since configuration files
6752 are kept on the system in this situation.
6756 Any <tt>cron</tt> daemon must provide
6757 <file>/usr/bin/crontab</file> and support normal
6758 <tt>crontab</tt> entries as specified in POSIX. The daemon
6759 must also support names for days and months, ranges, and
6760 step values. It has to support <file>/etc/crontab</file>,
6761 and correctly execute the scripts in
6762 <file>/etc/cron.d</file>. The daemon must also correctly
6764 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>.
6769 <heading>Menus</heading>
6772 The Debian <tt>menu</tt> package provides a standard
6773 interface between packages providing applications and
6774 <em>menu programs</em> (either X window managers or
6775 text-based menu programs such as <prgn>pdmenu</prgn>).
6779 All packages that provide applications that need not be
6780 passed any special command line arguments for normal
6781 operation should register a menu entry for those
6782 applications, so that users of the <tt>menu</tt> package
6783 will automatically get menu entries in their window
6784 managers, as well in shells like <tt>pdmenu</tt>.
6788 Menu entries should follow the current menu policy.
6792 The menu policy can be found in the <tt>menu-policy</tt>
6793 files in the <tt>debian-policy</tt> package.
6794 It is also available from the Debian web mirrors at
6795 <tt><url name="/doc/packaging-manuals/menu-policy/"
6796 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6800 Please also refer to the <em>Debian Menu System</em>
6801 documentation that comes with the <package>menu</package>
6802 package for information about how to register your
6808 <heading>Multimedia handlers</heading>
6811 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6812 is a mechanism for encoding files and data streams and
6813 providing meta-information about them, in particular their
6814 type (e.g. audio or video) and format (e.g. PNG, HTML,
6819 Registration of MIME type handlers allows programs like mail
6820 user agents and web browsers to invoke these handlers to
6821 view, edit or display MIME types they don't support directly.
6825 Packages which provide the ability to view/show/play,
6826 compose, edit or print MIME types should register themselves
6827 as such following the current MIME support policy.
6831 The MIME support policy can be found in the <tt>mime-policy</tt>
6832 files in the <tt>debian-policy</tt> package.
6833 It is also available from the Debian web mirrors at
6834 <tt><url name="/doc/packaging-manuals/mime-policy/"
6835 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6841 <heading>Keyboard configuration</heading>
6844 To achieve a consistent keyboard configuration so that all
6845 applications interpret a keyboard event the same way, all
6846 programs in the Debian distribution must be configured to
6847 comply with the following guidelines.
6851 The following keys must have the specified interpretations:
6854 <tag><tt><--</tt></tag>
6855 <item>delete the character to the left of the cursor</item>
6857 <tag><tt>Delete</tt></tag>
6858 <item>delete the character to the right of the cursor</item>
6860 <tag><tt>Control+H</tt></tag>
6861 <item>emacs: the help prefix</item>
6864 The interpretation of any keyboard events should be
6865 independent of the terminal that is used, be it a virtual
6866 console, an X terminal emulator, an rlogin/telnet session,
6871 The following list explains how the different programs
6872 should be set up to achieve this:
6878 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6882 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6886 X translations are set up to make
6887 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6888 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6889 is the vt220 escape code for the "delete character"
6890 key). This must be done by loading the X resources
6891 using <prgn>xrdb</prgn> on all local X displays, not
6892 using the application defaults, so that the
6893 translation resources used correspond to the
6894 <prgn>xmodmap</prgn> settings.
6898 The Linux console is configured to make
6899 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6900 generate <tt>ESC [ 3 ~</tt>.
6904 X applications are configured so that <tt><</tt>
6905 deletes left, and <tt>Delete</tt> deletes right. Motif
6906 applications already work like this.
6910 Terminals should have <tt>stty erase ^?</tt> .
6914 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6915 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6916 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6920 Emacs is programmed to map <tt>KB_Backspace</tt> or
6921 the <tt>stty erase</tt> character to
6922 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6923 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6924 <tt>^H</tt> to <tt>help</tt> as always.
6928 Other applications use the <tt>stty erase</tt>
6929 character and <tt>kdch1</tt> for the two delete keys,
6930 with ASCII DEL being "delete previous character" and
6931 <tt>kdch1</tt> being "delete character under
6939 This will solve the problem except for the following
6946 Some terminals have a <tt><--</tt> key that cannot
6947 be made to produce anything except <tt>^H</tt>. On
6948 these terminals Emacs help will be unavailable on
6949 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6950 character takes precedence in Emacs, and has been set
6951 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6952 available) can be used instead.
6956 Some operating systems use <tt>^H</tt> for <tt>stty
6957 erase</tt>. However, modern telnet versions and all
6958 rlogin versions propagate <tt>stty</tt> settings, and
6959 almost all UNIX versions honour <tt>stty erase</tt>.
6960 Where the <tt>stty</tt> settings are not propagated
6961 correctly, things can be made to work by using
6962 <tt>stty</tt> manually.
6966 Some systems (including previous Debian versions) use
6967 <prgn>xmodmap</prgn> to arrange for both
6968 <tt><--</tt> and <tt>Delete</tt> to generate
6969 <tt>KB_Delete</tt>. We can change the behavior of
6970 their X clients using the same X resources that we use
6971 to do it for our own clients, or configure our clients
6972 using their resources when things are the other way
6973 around. On displays configured like this
6974 <tt>Delete</tt> will not work, but <tt><--</tt>
6979 Some operating systems have different <tt>kdch1</tt>
6980 settings in their <tt>terminfo</tt> database for
6981 <tt>xterm</tt> and others. On these systems the
6982 <tt>Delete</tt> key will not work correctly when you
6983 log in from a system conforming to our policy, but
6984 <tt><--</tt> will.
6991 <heading>Environment variables</heading>
6994 A program must not depend on environment variables to get
6995 reasonable defaults. (That's because these environment
6996 variables would have to be set in a system-wide
6997 configuration file like <file>/etc/profile</file>, which is not
6998 supported by all shells.)
7002 If a program usually depends on environment variables for its
7003 configuration, the program should be changed to fall back to
7004 a reasonable default configuration if these environment
7005 variables are not present. If this cannot be done easily
7006 (e.g., if the source code of a non-free program is not
7007 available), the program must be replaced by a small
7008 "wrapper" shell script which sets the environment variables
7009 if they are not already defined, and calls the original program.
7013 Here is an example of a wrapper script for this purpose:
7015 <example compact="compact">
7017 BAR=${BAR:-/var/lib/fubar}
7019 exec /usr/lib/foo/foo "$@"
7024 Furthermore, as <file>/etc/profile</file> is a configuration
7025 file of the <prgn>base-files</prgn> package, other packages must
7026 not put any environment variables or other commands into that
7031 <sect id="doc-base">
7032 <heading>Registering Documents using doc-base</heading>
7035 The <package>doc-base</package> package implements a
7036 flexible mechanism for handling and presenting
7037 documentation. The recommended practice is for every Debian
7038 package that provides online documentation (other than just
7039 manual pages) to register these documents with
7040 <package>doc-base</package> by installing a
7041 <package>doc-base</package> control file via the
7042 <prgn/install-docs/ script at installation time and
7043 de-register the manuals again when the package is removed.
7046 Please refer to the documentation that comes with the
7047 <package>doc-base</package> package for information and
7056 <heading>Files</heading>
7059 <heading>Binaries</heading>
7062 Two different packages must not install programs with
7063 different functionality but with the same filenames. (The
7064 case of two programs having the same functionality but
7065 different implementations is handled via "alternatives" or
7066 the "Conflicts" mechanism. See <ref id="maintscripts"> and
7067 <ref id="conflicts"> respectively.) If this case happens,
7068 one of the programs must be renamed. The maintainers should
7069 report this to the <tt>debian-devel</tt> mailing list and
7070 try to find a consensus about which program will have to be
7071 renamed. If a consensus cannot be reached, <em>both</em>
7072 programs must be renamed.
7076 By default, when a package is being built, any binaries
7077 created should include debugging information, as well as
7078 being compiled with optimization. You should also turn on
7079 as many reasonable compilation warnings as possible; this
7080 makes life easier for porters, who can then look at build
7081 logs for possible problems. For the C programming language,
7082 this means the following compilation parameters should be
7084 <example compact="compact">
7086 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
7088 INSTALL = install -s # (or use strip on the files in debian/tmp)
7093 Note that by default all installed binaries should be stripped,
7094 either by using the <tt>-s</tt> flag to
7095 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
7096 the binaries after they have been copied into
7097 <file>debian/tmp</file> but before the tree is made into a
7102 Although binaries in the build tree should be compiled with
7103 debugging information by default, it can often be difficult to
7104 debug programs if they are also subjected to compiler
7105 optimization. For this reason, it is recommended to support the
7106 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
7107 (see <ref id="debianrules-options">). This variable can contain
7108 several flags to change how a package is compiled and built.
7112 It is up to the package maintainer to decide what
7113 compilation options are best for the package. Certain
7114 binaries (such as computationally-intensive programs) will
7115 function better with certain flags (<tt>-O3</tt>, for
7116 example); feel free to use them. Please use good judgment
7117 here. Don't use flags for the sake of it; only use them
7118 if there is good reason to do so. Feel free to override
7119 the upstream author's ideas about which compilation
7120 options are best: they are often inappropriate for our
7126 <sect id="libraries">
7127 <heading>Libraries</heading>
7130 If the package is <strong>architecture: any</strong>, then
7131 the shared library compilation and linking flags must have
7132 <tt>-fPIC</tt>, or the package shall not build on some of
7133 the supported architectures<footnote>
7135 If you are using GCC, <tt>-fPIC</tt> produces code with
7136 relocatable position independent code, which is required for
7137 most architectures to create a shared library, with i386 and
7138 perhaps some others where non position independent code is
7139 permitted in a shared library.
7142 Position independent code may have a performance penalty,
7143 especially on <tt>i386</tt>. However, in most cases the
7144 speed penalty must be measured against the memory wasted on
7145 the few architectures where non position independent code is
7148 </footnote>. Any exception to this rule must be discussed on
7149 the mailing list <em>debian-devel@lists.debian.org</em>, and
7150 a rough consensus obtained. The reasons for not compiling
7151 with <tt>-fPIC</tt> flag must be recorded in the file
7152 <tt>README.Debian</tt>, and care must be taken to either
7153 restrict the architecture or arrange for <tt>-fPIC</tt> to
7154 be used on architectures where it is required.<footnote>
7156 Some of the reasons why this might be required is if the
7157 library contains hand crafted assembly code that is not
7158 relocatable, the speed penalty is excessive for compute
7159 intensive libs, and similar reasons.
7164 As to the static libraries, the common case is not to have
7165 relocatable code, since there is no benefit, unless in specific
7166 cases; therefore the static version must not be compiled
7167 with the <tt>-fPIC</tt> flag. Any exception to this rule
7168 should be discussed on the mailing list
7169 <em>debian-devel@lists.debian.org</em>, and the reasons for
7170 compiling with the <tt>-fPIC</tt> flag must be recorded in
7171 the file <tt>README.Debian</tt>. <footnote>
7173 Some of the reasons for linking static libraries with
7174 the <tt>-fPIC</tt> flag are if, for example, one needs a
7175 Perl API for a library that is under rapid development,
7176 and has an unstable API, so shared libraries are
7177 pointless at this phase of the library's development. In
7178 that case, since Perl needs a library with relocatable
7179 code, it may make sense to create a static library with
7180 relocatable code. Another reason cited is if you are
7181 distilling various libraries into a common shared
7182 library, like <tt>mklibs</tt> does in the Debian
7188 In other words, if both a shared and a static library is
7189 being built, each source unit (<tt>*.c</tt>, for example,
7190 for C files) will need to be compiled twice, for the normal
7194 You must specify the gcc option <tt>-D_REENTRANT</tt>
7195 when building a library (either static or shared) to make
7196 the library compatible with LinuxThreads.
7200 Although not enforced by the build tools, shared libraries
7201 must be linked against all libraries that they use symbols from
7202 in the same way that binaries are. This ensures the correct
7203 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
7204 system and guarantees that all libraries can be safely opened
7205 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
7206 option <tt>-Wl,-z,defs</tt> when building a shared library.
7207 Since this option enforces symbol resolution at build time,
7208 a missing library reference will be caught early as a fatal
7213 All installed shared libraries should be stripped with
7214 <example compact="compact">
7215 strip --strip-unneeded <var>your-lib</var>
7217 (The option <tt>--strip-unneeded</tt> makes
7218 <prgn>strip</prgn> remove only the symbols which aren't
7219 needed for relocation processing.) Shared libraries can
7220 function perfectly well when stripped, since the symbols for
7221 dynamic linking are in a separate part of the ELF object
7223 You might also want to use the options
7224 <tt>--remove-section=.comment</tt> and
7225 <tt>--remove-section=.note</tt> on both shared libraries
7226 and executables, and <tt>--strip-debug</tt> on static
7232 Note that under some circumstances it may be useful to
7233 install a shared library unstripped, for example when
7234 building a separate package to support debugging.
7238 Shared object files (often <file>.so</file> files) that are not
7239 public libraries, that is, they are not meant to be linked
7240 to by third party executables (binaries of other packages),
7241 should be installed in subdirectories of the
7242 <file>/usr/lib</file> directory. Such files are exempt from the
7243 rules that govern ordinary shared libraries, except that
7244 they must not be installed executable and should be
7246 A common example are the so-called "plug-ins",
7247 internal shared objects that are dynamically loaded by
7248 programs using <manref name="dlopen" section="3">.
7253 An ever increasing number of packages are using
7254 <prgn>libtool</prgn> to do their linking. The latest GNU
7255 libtools (>= 1.3a) can take advantage of the metadata in the
7256 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
7257 files). The main advantage of <prgn>libtool</prgn>'s
7258 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
7259 store and subsequently access metadata with respect to the
7260 libraries it builds. <prgn>libtool</prgn> will search for
7261 those files, which contain a lot of useful information about
7262 a library (such as library dependency information for static
7263 linking). Also, they're <em>essential</em> for programs
7264 using <tt>libltdl</tt>.<footnote>
7265 Although <prgn>libtool</prgn> is fully capable of
7266 linking against shared libraries which don't have
7267 <tt>.la</tt> files, as it is a mere shell script it can
7268 add considerably to the build time of a
7269 <prgn>libtool</prgn>-using package if that shell script
7270 has to derive all this information from first principles
7271 for each library every time it is linked. With the
7272 advent of <prgn>libtool</prgn> version 1.4 (and to a
7273 lesser extent <prgn>libtool</prgn> version 1.3), the
7274 <file>.la</file> files also store information about
7275 inter-library dependencies which cannot necessarily be
7276 derived after the <file>.la</file> file is deleted.
7281 Packages that use <prgn>libtool</prgn> to create shared
7282 libraries should include the <file>.la</file> files in the
7283 <tt>-dev</tt> package, unless the package relies on
7284 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
7285 the <tt>.la</tt> files must go in the run-time library
7290 You must make sure that you use only released versions of
7291 shared libraries to build your packages; otherwise other
7292 users will not be able to run your binaries
7293 properly. Producing source packages that depend on
7294 unreleased compilers is also usually a bad
7301 <heading>Shared libraries</heading>
7303 This section has moved to <ref id="sharedlibs">.
7309 <heading>Scripts</heading>
7312 All command scripts, including the package maintainer
7313 scripts inside the package and used by <prgn>dpkg</prgn>,
7314 should have a <tt>#!</tt> line naming the shell to be used
7319 In the case of Perl scripts this should be
7320 <tt>#!/usr/bin/perl</tt>.
7324 When scripts are installed into a directory in the system
7325 PATH, the script name should not include an extension such
7326 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7327 language currently used to implement it.
7330 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>) other than
7331 <file>init.d</file> scripts should almost certainly start
7332 with <tt>set -e</tt> so that errors are detected.
7333 <file>init.d</file> scripts are something of a special case, due
7334 to how frequently they need to call commands that are allowed to
7335 fail, and it may instead be easier to check the exit status of
7336 commands directly. See <ref id="writing-init"> for more
7337 information about writing <file>init.d</file> scripts.
7340 Every script should use <tt>set -e</tt> or check the exit status
7341 of <em>every</em> command.
7344 Scripts may assume that <file>/bin/sh</file> implements the
7345 SUSv3 Shell Command Language<footnote>
7346 Single UNIX Specification, version 3, which is also IEEE
7347 1003.1-2004 (POSIX), and is available on the World Wide Web
7348 from <url id="http://www.unix.org/version3/online.html"
7349 name="The Open Group"> after free
7350 registration.</footnote>
7351 plus the following additional features not mandated by
7353 These features are in widespread use in the Linux community
7354 and are implemented in all of bash, dash, and ksh, the most
7355 common shells users may wish to use as <file>/bin/sh</file>.
7358 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7359 must not generate a newline.</item>
7360 <item><tt>test</tt>, if implemented as a shell built-in, must
7361 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7363 <item><tt>local</tt> to create a scoped variable must be
7364 supported, including listing multiple variables in a single
7365 local command and assigning a value to a variable at the
7366 same time as localizing it. <tt>local</tt> may or
7367 may not preserve the variable value from an outer scope if
7368 no assignment is present. Uses such as:
7372 # ... use a, b, c, d ...
7375 must be supported and must set the value of <tt>c</tt> to
7379 If a shell script requires non-SUSv3 features from the shell
7380 interpreter other than those listed above, the appropriate shell
7381 must be specified in the first line of the script (e.g.,
7382 <tt>#!/bin/bash</tt>) and the package must depend on the package
7383 providing the shell (unless the shell package is marked
7384 "Essential", as in the case of <prgn>bash</prgn>).
7388 You may wish to restrict your script to SUSv3 features plus the
7389 above set when possible so that it may use <file>/bin/sh</file>
7390 as its interpreter. If your script works with <prgn>dash</prgn>
7391 (originally called <prgn>ash</prgn>), it probably complies with
7392 the above requirements, but if you are in doubt, use
7393 <file>/bin/bash</file>.
7397 Perl scripts should check for errors when making any
7398 system calls, including <tt>open</tt>, <tt>print</tt>,
7399 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7403 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7404 scripting languages. See <em>Csh Programming Considered
7405 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7406 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7407 If an upstream package comes with <prgn>csh</prgn> scripts
7408 then you must make sure that they start with
7409 <tt>#!/bin/csh</tt> and make your package depend on the
7410 <prgn>c-shell</prgn> virtual package.
7414 Any scripts which create files in world-writeable
7415 directories (e.g., in <file>/tmp</file>) must use a
7416 mechanism which will fail atomically if a file with the same
7417 name already exists.
7421 The Debian base system provides the <prgn>tempfile</prgn>
7422 and <prgn>mktemp</prgn> utilities for use by scripts for
7429 <heading>Symbolic links</heading>
7432 In general, symbolic links within a top-level directory
7433 should be relative, and symbolic links pointing from one
7434 top-level directory into another should be absolute. (A
7435 top-level directory is a sub-directory of the root
7436 directory <file>/</file>.)
7440 In addition, symbolic links should be specified as short as
7441 possible, i.e., link targets like <file>foo/../bar</file> are
7446 Note that when creating a relative link using
7447 <prgn>ln</prgn> it is not necessary for the target of the
7448 link to exist relative to the working directory you're
7449 running <prgn>ln</prgn> from, nor is it necessary to change
7450 directory to the directory where the link is to be made.
7451 Simply include the string that should appear as the target
7452 of the link (this will be a pathname relative to the
7453 directory in which the link resides) as the first argument
7458 For example, in your <prgn>Makefile</prgn> or
7459 <file>debian/rules</file>, you can do things like:
7460 <example compact="compact">
7461 ln -fs gcc $(prefix)/bin/cc
7462 ln -fs gcc debian/tmp/usr/bin/cc
7463 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7464 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7469 A symbolic link pointing to a compressed file should always
7470 have the same file extension as the referenced file. (For
7471 example, if a file <file>foo.gz</file> is referenced by a
7472 symbolic link, the filename of the link has to end with
7473 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7478 <heading>Device files</heading>
7481 Packages must not include device files or named pipes in the
7486 If a package needs any special device files that are not
7487 included in the base system, it must call
7488 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7489 after notifying the user<footnote>
7490 This notification could be done via a (low-priority)
7491 debconf message, or an echo (printf) statement.
7496 Packages must not remove any device files in the
7497 <prgn>postrm</prgn> or any other script. This is left to the
7498 system administrator.
7502 Debian uses the serial devices
7503 <file>/dev/ttyS*</file>. Programs using the old
7504 <file>/dev/cu*</file> devices should be changed to use
7505 <file>/dev/ttyS*</file>.
7509 Named pipes needed by the package must be created in
7510 the <prgn>postinst</prgn> script<footnote>
7511 It's better to use <prgn>mkfifo</prgn> rather
7512 than <prgn>mknod</prgn> to create named pipes so that
7513 automated checks for packages incorrectly creating device
7514 files with <prgn>mknod</prgn> won't have false positives.
7515 </footnote> and removed in
7516 the <prgn>prerm</prgn> or <prgn>postrm</prgn> script as
7521 <sect id="config-files">
7522 <heading>Configuration files</heading>
7525 <heading>Definitions</heading>
7529 <tag>configuration file</tag>
7531 A file that affects the operation of a program, or
7532 provides site- or host-specific information, or
7533 otherwise customizes the behavior of a program.
7534 Typically, configuration files are intended to be
7535 modified by the system administrator (if needed or
7536 desired) to conform to local policy or to provide
7537 more useful site-specific behavior.
7540 <tag><tt>conffile</tt></tag>
7542 A file listed in a package's <tt>conffiles</tt>
7543 file, and is treated specially by <prgn>dpkg</prgn>
7544 (see <ref id="configdetails">).
7550 The distinction between these two is important; they are
7551 not interchangeable concepts. Almost all
7552 <tt>conffile</tt>s are configuration files, but many
7553 configuration files are not <tt>conffiles</tt>.
7557 As noted elsewhere, <file>/etc/init.d</file> scripts,
7558 <file>/etc/default</file> files, scripts installed in
7559 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7560 configuration installed in <file>/etc/cron.d</file> must be
7561 treated as configuration files. In general, any script that
7562 embeds configuration information is de-facto a configuration
7563 file and should be treated as such.
7568 <heading>Location</heading>
7571 Any configuration files created or used by your package
7572 must reside in <file>/etc</file>. If there are several,
7573 consider creating a subdirectory of <file>/etc</file>
7574 named after your package.
7578 If your package creates or uses configuration files
7579 outside of <file>/etc</file>, and it is not feasible to modify
7580 the package to use <file>/etc</file> directly, put the files
7581 in <file>/etc</file> and create symbolic links to those files
7582 from the location that the package requires.
7587 <heading>Behavior</heading>
7590 Configuration file handling must conform to the following
7592 <list compact="compact">
7594 local changes must be preserved during a package
7598 configuration files must be preserved when the
7599 package is removed, and only deleted when the
7603 Obsolete configuration files without local changes may be
7604 removed by the package during upgrade.
7608 The easy way to achieve this behavior is to make the
7609 configuration file a <tt>conffile</tt>. This is
7610 appropriate only if it is possible to distribute a default
7611 version that will work for most installations, although
7612 some system administrators may choose to modify it. This
7613 implies that the default version will be part of the
7614 package distribution, and must not be modified by the
7615 maintainer scripts during installation (or at any other
7620 In order to ensure that local changes are preserved
7621 correctly, no package may contain or make hard links to
7622 conffiles.<footnote>
7623 Rationale: There are two problems with hard links.
7624 The first is that some editors break the link while
7625 editing one of the files, so that the two files may
7626 unwittingly become unlinked and different. The second
7627 is that <prgn>dpkg</prgn> might break the hard link
7628 while upgrading <tt>conffile</tt>s.
7633 The other way to do it is via the maintainer scripts. In
7634 this case, the configuration file must not be listed as a
7635 <tt>conffile</tt> and must not be part of the package
7636 distribution. If the existence of a file is required for
7637 the package to be sensibly configured it is the
7638 responsibility of the package maintainer to provide
7639 maintainer scripts which correctly create, update and
7640 maintain the file and remove it on purge. (See <ref
7641 id="maintainerscripts"> for more information.) These
7642 scripts must be idempotent (i.e., must work correctly if
7643 <prgn>dpkg</prgn> needs to re-run them due to errors
7644 during installation or removal), must cope with all the
7645 variety of ways <prgn>dpkg</prgn> can call maintainer
7646 scripts, must not overwrite or otherwise mangle the user's
7647 configuration without asking, must not ask unnecessary
7648 questions (particularly during upgrades), and must
7649 otherwise be good citizens.
7653 The scripts are not required to configure every possible
7654 option for the package, but only those necessary to get
7655 the package running on a given system. Ideally the
7656 sysadmin should not have to do any configuration other
7657 than that done (semi-)automatically by the
7658 <prgn>postinst</prgn> script.
7662 A common practice is to create a script called
7663 <file><var>package</var>-configure</file> and have the
7664 package's <prgn>postinst</prgn> call it if and only if the
7665 configuration file does not already exist. In certain
7666 cases it is useful for there to be an example or template
7667 file which the maintainer scripts use. Such files should
7668 be in <file>/usr/share/<var>package</var></file> or
7669 <file>/usr/lib/<var>package</var></file> (depending on whether
7670 they are architecture-independent or not). There should
7671 be symbolic links to them from
7672 <file>/usr/share/doc/<var>package</var>/examples</file> if
7673 they are examples, and should be perfectly ordinary
7674 <prgn>dpkg</prgn>-handled files (<em>not</em>
7675 configuration files).
7679 These two styles of configuration file handling must
7680 not be mixed, for that way lies madness:
7681 <prgn>dpkg</prgn> will ask about overwriting the file
7682 every time the package is upgraded.
7687 <heading>Sharing configuration files</heading>
7690 Packages which specify the same file as a
7691 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7692 with each other. (This is an instance of the general rule
7693 about not sharing files. Note that neither alternatives
7694 nor diversions are likely to be appropriate in this case;
7695 in particular, <prgn>dpkg</prgn> does not handle diverted
7696 <tt>conffile</tt>s well.)
7700 The maintainer scripts must not alter a <tt>conffile</tt>
7701 of <em>any</em> package, including the one the scripts
7706 If two or more packages use the same configuration file
7707 and it is reasonable for both to be installed at the same
7708 time, one of these packages must be defined as
7709 <em>owner</em> of the configuration file, i.e., it will be
7710 the package which handles that file as a configuration
7711 file. Other packages that use the configuration file must
7712 depend on the owning package if they require the
7713 configuration file to operate. If the other package will
7714 use the configuration file if present, but is capable of
7715 operating without it, no dependency need be declared.
7719 If it is desirable for two or more related packages to
7720 share a configuration file <em>and</em> for all of the
7721 related packages to be able to modify that configuration
7722 file, then the following should be done:
7723 <enumlist compact="compact">
7725 One of the related packages (the "owning" package)
7726 will manage the configuration file with maintainer
7727 scripts as described in the previous section.
7730 The owning package should also provide a program
7731 that the other packages may use to modify the
7735 The related packages must use the provided program
7736 to make any desired modifications to the
7737 configuration file. They should either depend on
7738 the core package to guarantee that the configuration
7739 modifier program is available or accept gracefully
7740 that they cannot modify the configuration file if it
7741 is not. (This is in addition to the fact that the
7742 configuration file may not even be present in the
7749 Sometimes it's appropriate to create a new package which
7750 provides the basic infrastructure for the other packages
7751 and which manages the shared configuration files. (The
7752 <tt>sgml-base</tt> package is a good example.)
7757 <heading>User configuration files ("dotfiles")</heading>
7760 The files in <file>/etc/skel</file> will automatically be
7761 copied into new user accounts by <prgn>adduser</prgn>.
7762 No other program should reference the files in
7763 <file>/etc/skel</file>.
7767 Therefore, if a program needs a dotfile to exist in
7768 advance in <file>$HOME</file> to work sensibly, that dotfile
7769 should be installed in <file>/etc/skel</file> and treated as a
7774 However, programs that require dotfiles in order to
7775 operate sensibly are a bad thing, unless they do create
7776 the dotfiles themselves automatically.
7780 Furthermore, programs should be configured by the Debian
7781 default installation to behave as closely to the upstream
7782 default behavior as possible.
7786 Therefore, if a program in a Debian package needs to be
7787 configured in some way in order to operate sensibly, that
7788 should be done using a site-wide configuration file placed
7789 in <file>/etc</file>. Only if the program doesn't support a
7790 site-wide default configuration and the package maintainer
7791 doesn't have time to add it may a default per-user file be
7792 placed in <file>/etc/skel</file>.
7796 <file>/etc/skel</file> should be as empty as we can make it.
7797 This is particularly true because there is no easy (or
7798 necessarily desirable) mechanism for ensuring that the
7799 appropriate dotfiles are copied into the accounts of
7800 existing users when a package is installed.
7806 <heading>Log files</heading>
7808 Log files should usually be named
7809 <file>/var/log/<var>package</var>.log</file>. If you have many
7810 log files, or need a separate directory for permission
7811 reasons (<file>/var/log</file> is writable only by
7812 <file>root</file>), you should usually create a directory named
7813 <file>/var/log/<var>package</var></file> and place your log
7818 Log files must be rotated occasionally so that they don't
7819 grow indefinitely; the best way to do this is to drop a log
7820 rotation configuration file into the directory
7821 <file>/etc/logrotate.d</file> and use the facilities provided by
7822 logrotate.<footnote>
7824 The traditional approach to log files has been to set up
7825 <em>ad hoc</em> log rotation schemes using simple shell
7826 scripts and cron. While this approach is highly
7827 customizable, it requires quite a lot of sysadmin work.
7828 Even though the original Debian system helped a little
7829 by automatically installing a system which can be used
7830 as a template, this was deemed not enough.
7834 The use of <prgn>logrotate</prgn>, a program developed
7835 by Red Hat, is better, as it centralizes log management.
7836 It has both a configuration file
7837 (<file>/etc/logrotate.conf</file>) and a directory where
7838 packages can drop their individual log rotation
7839 configurations (<file>/etc/logrotate.d</file>).
7842 Here is a good example for a logrotate config
7843 file (for more information see <manref name="logrotate"
7845 <example compact="compact">
7846 /var/log/foo/*.log {
7851 /etc/init.d/foo force-reload
7855 This rotates all files under <file>/var/log/foo</file>, saves 12
7856 compressed generations, and forces the daemon to reload its
7857 configuration information after the log rotation.
7861 Log files should be removed when the package is
7862 purged (but not when it is only removed). This should be
7863 done by the <prgn>postrm</prgn> script when it is called
7864 with the argument <tt>purge</tt> (see <ref
7865 id="removedetails">).
7870 <heading>Permissions and owners</heading>
7873 The rules in this section are guidelines for general use.
7874 If necessary you may deviate from the details below.
7875 However, if you do so you must make sure that what is done
7876 is secure and you should try to be as consistent as possible
7877 with the rest of the system. You should probably also
7878 discuss it on <prgn>debian-devel</prgn> first.
7882 Files should be owned by <tt>root:root</tt>, and made
7883 writable only by the owner and universally readable (and
7884 executable, if appropriate), that is mode 644 or 755.
7888 Directories should be mode 755 or (for group-writability)
7889 mode 2775. The ownership of the directory should be
7890 consistent with its mode: if a directory is mode 2775, it
7891 should be owned by the group that needs write access to
7894 When a package is upgraded, and the owner or permissions
7895 of a file included in the package has changed, dpkg
7896 arranges for the ownership and permissions to be
7897 correctly set upon installation. However, this does not
7898 extend to directories; the permissions and ownership of
7899 directories already on the system does not change on
7900 install or upgrade of packages. This makes sense, since
7901 otherwise common directories like <tt>/usr</tt> would
7902 always be in flux. To correctly change permissions of a
7903 directory the package owns, explicit action is required,
7904 usually in the <tt>postinst</tt> script. Care must be
7905 taken to handle downgrades as well, in that case.
7912 Setuid and setgid executables should be mode 4755 or 2755
7913 respectively, and owned by the appropriate user or group.
7914 They should not be made unreadable (modes like 4711 or
7915 2711 or even 4111); doing so achieves no extra security,
7916 because anyone can find the binary in the freely available
7917 Debian package; it is merely inconvenient. For the same
7918 reason you should not restrict read or execute permissions
7919 on non-set-id executables.
7923 Some setuid programs need to be restricted to particular
7924 sets of users, using file permissions. In this case they
7925 should be owned by the uid to which they are set-id, and by
7926 the group which should be allowed to execute them. They
7927 should have mode 4754; again there is no point in making
7928 them unreadable to those users who must not be allowed to
7933 It is possible to arrange that the system administrator can
7934 reconfigure the package to correspond to their local
7935 security policy by changing the permissions on a binary:
7936 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7937 described below.<footnote>
7938 Ordinary files installed by <prgn>dpkg</prgn> (as
7939 opposed to <tt>conffile</tt>s and other similar objects)
7940 normally have their permissions reset to the distributed
7941 permissions when the package is reinstalled. However,
7942 the use of <prgn>dpkg-statoverride</prgn> overrides this
7945 Another method you should consider is to create a group for
7946 people allowed to use the program(s) and make any setuid
7947 executables executable only by that group.
7951 If you need to create a new user or group for your package
7952 there are two possibilities. Firstly, you may need to
7953 make some files in the binary package be owned by this
7954 user or group, or you may need to compile the user or
7955 group id (rather than just the name) into the binary
7956 (though this latter should be avoided if possible, as in
7957 this case you need a statically allocated id).</p>
7960 If you need a statically allocated id, you must ask for a
7961 user or group id from the <tt>base-passwd</tt> maintainer,
7962 and must not release the package until you have been
7963 allocated one. Once you have been allocated one you must
7964 either make the package depend on a version of the
7965 <tt>base-passwd</tt> package with the id present in
7966 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7967 your package to create the user or group itself with the
7968 correct id (using <tt>adduser</tt>) in its
7969 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7970 the <prgn>postinst</prgn> is to be preferred if it is
7971 possible, otherwise a pre-dependency will be needed on the
7972 <tt>adduser</tt> package.)
7976 On the other hand, the program might be able to determine
7977 the uid or gid from the user or group name at runtime, so
7978 that a dynamically allocated id can be used. In this case
7979 you should choose an appropriate user or group name,
7980 discussing this on <prgn>debian-devel</prgn> and checking
7981 with the <package/base-passwd/ maintainer that it is unique and that
7982 they do not wish you to use a statically allocated id
7983 instead. When this has been checked you must arrange for
7984 your package to create the user or group if necessary using
7985 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7986 <prgn>postinst</prgn> script (again, the latter is to be
7987 preferred if it is possible).
7991 Note that changing the numeric value of an id associated
7992 with a name is very difficult, and involves searching the
7993 file system for all appropriate files. You need to think
7994 carefully whether a static or dynamic id is required, since
7995 changing your mind later will cause problems.
7998 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
8000 This section is not intended as policy, but as a
8001 description of the use of <prgn>dpkg-statoverride</prgn>.
8005 If a system administrator wishes to have a file (or
8006 directory or other such thing) installed with owner and
8007 permissions different from those in the distributed Debian
8008 package, they can use the <prgn>dpkg-statoverride</prgn>
8009 program to instruct <prgn>dpkg</prgn> to use the different
8010 settings every time the file is installed. Thus the
8011 package maintainer should distribute the files with their
8012 normal permissions, and leave it for the system
8013 administrator to make any desired changes. For example, a
8014 daemon which is normally required to be setuid root, but
8015 in certain situations could be used without being setuid,
8016 should be installed setuid in the <tt>.deb</tt>. Then the
8017 local system administrator can change this if they wish.
8018 If there are two standard ways of doing it, the package
8019 maintainer can use <tt>debconf</tt> to find out the
8020 preference, and call <prgn>dpkg-statoverride</prgn> in the
8021 maintainer script if necessary to accommodate the system
8022 administrator's choice. Care must be taken during
8023 upgrades to not override an existing setting.
8027 Given the above, <prgn>dpkg-statoverride</prgn> is
8028 essentially a tool for system administrators and would not
8029 normally be needed in the maintainer scripts. There is
8030 one type of situation, though, where calls to
8031 <prgn>dpkg-statoverride</prgn> would be needed in the
8032 maintainer scripts, and that involves packages which use
8033 dynamically allocated user or group ids. In such a
8034 situation, something like the following idiom can be very
8035 helpful in the package's <prgn>postinst</prgn>, where
8036 <tt>sysuser</tt> is a dynamically allocated id:
8038 for i in /usr/bin/foo /usr/sbin/bar
8040 # only do something when no setting exists
8041 if ! dpkg-statoverride --list $i >/dev/null 2>&1
8043 #include: debconf processing, question about foo and bar
8044 if [ "$RET" = "true" ] ; then
8045 dpkg-statoverride --update --add sysuser root 4755 $i
8050 The corresponding code to remove the override when the package
8053 for i in /usr/bin/foo /usr/sbin/bar
8055 if dpkg-statoverride --list $i >/dev/null 2>&1
8057 dpkg-statoverride --remove $i
8067 <chapt id="customized-programs">
8068 <heading>Customized programs</heading>
8070 <sect id="arch-spec">
8071 <heading>Architecture specification strings</heading>
8074 If a program needs to specify an <em>architecture specification
8075 string</em> in some place, it should select one of the strings
8076 provided by <tt>dpkg-architecture -L</tt>. The strings are in
8077 the format <tt><var>os</var>-<var>arch</var></tt>, though the OS
8078 part is sometimes elided, as when the OS is Linux.
8082 Note that we don't want to use
8083 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
8084 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
8085 since this would make our programs incompatible with other
8086 Linux distributions. We also don't use something like
8087 <tt><var>arch</var>-unknown-linux</tt>, since the
8088 <tt>unknown</tt> does not look very good.
8091 <sect1 id="arch-wildcard-spec">
8092 <heading>Architecture wildcards</heading>
8095 A package may specify an architecture wildcard. Architecture
8096 wildcards are in the format <tt>any</tt> (which matches every
8097 architecture), <tt><var>os</var></tt>-any, or
8098 any-<tt><var>cpu</var></tt>. <footnote>
8099 Internally, the package system normalizes the GNU triplets
8100 and the Debian arches into Debian arch triplets (which are
8101 kind of inverted GNU triplets), with the first component of
8102 the triplet representing the libc and ABI in use, and then
8103 does matching against those triplets. However, such
8104 triplets are an internal implementation detail that should
8105 not be used by packages directly. The libc and ABI portion
8106 is handled internally by the package system based on
8107 the <var>os</var> and <var>cpu</var>.
8114 <heading>Daemons</heading>
8117 The configuration files <file>/etc/services</file>,
8118 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
8119 by the <prgn>netbase</prgn> package and must not be modified
8124 If a package requires a new entry in one of these files, the
8125 maintainer should get in contact with the
8126 <prgn>netbase</prgn> maintainer, who will add the entries
8127 and release a new version of the <prgn>netbase</prgn>
8132 The configuration file <file>/etc/inetd.conf</file> must not be
8133 modified by the package's scripts except via the
8134 <prgn>update-inetd</prgn> script or the
8135 <file>DebianNet.pm</file> Perl module. See their documentation
8136 for details on how to add entries.
8140 If a package wants to install an example entry into
8141 <file>/etc/inetd.conf</file>, the entry must be preceded with
8142 exactly one hash character (<tt>#</tt>). Such lines are
8143 treated as "commented out by user" by the
8144 <prgn>update-inetd</prgn> script and are not changed or
8145 activated during package updates.
8150 <heading>Using pseudo-ttys and modifying wtmp, utmp and
8154 Some programs need to create pseudo-ttys. This should be done
8155 using Unix98 ptys if the C library supports it. The resulting
8156 program must not be installed setuid root, unless that
8157 is required for other functionality.
8161 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
8162 <file>/var/log/lastlog</file> must be installed writable by
8163 group <tt>utmp</tt>. Programs which need to modify those
8164 files must be installed setgid <tt>utmp</tt>.
8169 <heading>Editors and pagers</heading>
8172 Some programs have the ability to launch an editor or pager
8173 program to edit or display a text document. Since there are
8174 lots of different editors and pagers available in the Debian
8175 distribution, the system administrator and each user should
8176 have the possibility to choose their preferred editor and
8181 In addition, every program should choose a good default
8182 editor/pager if none is selected by the user or system
8187 Thus, every program that launches an editor or pager must
8188 use the EDITOR or PAGER environment variable to determine
8189 the editor or pager the user wishes to use. If these
8190 variables are not set, the programs <file>/usr/bin/editor</file>
8191 and <file>/usr/bin/pager</file> should be used, respectively.
8195 These two files are managed through the <prgn>dpkg</prgn>
8196 "alternatives" mechanism. Thus every package providing an
8197 editor or pager must call the
8198 <prgn>update-alternatives</prgn> script to register these
8203 If it is very hard to adapt a program to make use of the
8204 EDITOR or PAGER variables, that program may be configured to
8205 use <file>/usr/bin/sensible-editor</file> and
8206 <file>/usr/bin/sensible-pager</file> as the editor or pager
8207 program respectively. These are two scripts provided in the
8208 <package>sensible-utils</package> package that check the EDITOR
8209 and PAGER variables and launch the appropriate program, and fall
8210 back to <file>/usr/bin/editor</file>
8211 and <file>/usr/bin/pager</file> if the variable is not set.
8215 A program may also use the VISUAL environment variable to
8216 determine the user's choice of editor. If it exists, it
8217 should take precedence over EDITOR. This is in fact what
8218 <file>/usr/bin/sensible-editor</file> does.
8222 It is not required for a package to depend on
8223 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
8224 package to provide such virtual packages.<footnote>
8225 The Debian base system already provides an editor and a
8231 <sect id="web-appl">
8232 <heading>Web servers and applications</heading>
8235 This section describes the locations and URLs that should
8236 be used by all web servers and web applications in the
8243 Cgi-bin executable files are installed in the
8245 <example compact="compact">
8246 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
8248 and should be referred to as
8249 <example compact="compact">
8250 http://localhost/cgi-bin/<var>cgi-bin-name</var>
8256 <p>Access to HTML documents</p>
8259 HTML documents for a package are stored in
8260 <file>/usr/share/doc/<var>package</var></file>
8261 and can be referred to as
8262 <example compact="compact">
8263 http://localhost/doc/<var>package</var>/<var>filename</var>
8268 The web server should restrict access to the document
8269 tree so that only clients on the same host can read
8270 the documents. If the web server does not support such
8271 access controls, then it should not provide access at
8272 all, or ask about providing access during installation.
8277 <p>Access to images</p>
8279 It is recommended that images for a package be stored
8280 in <tt>/usr/share/images/<var>package</var></tt> and
8281 may be referred to through an alias <tt>/images/</tt>
8284 http://localhost/images/<package>/<filename>
8291 <p>Web Document Root</p>
8294 Web Applications should try to avoid storing files in
8295 the Web Document Root. Instead they should use the
8296 /usr/share/doc/<var>package</var> directory for
8297 documents and register the Web Application via the
8298 <package>doc-base</package> package. If access to the
8299 web document root is unavoidable then use
8300 <example compact="compact">
8303 as the Document Root. This might be just a symbolic
8304 link to the location where the system administrator
8305 has put the real document root.
8308 <item><p>Providing httpd and/or httpd-cgi</p>
8310 All web servers should provide the virtual package
8311 <tt>httpd</tt>. If a web server has CGI support it should
8312 provide <tt>httpd-cgi</tt> additionally.
8315 All web applications which do not contain CGI scripts should
8316 depend on <tt>httpd</tt>, all those web applications which
8317 <tt>do</tt> contain CGI scripts, should depend on
8325 <sect id="mail-transport-agents">
8326 <heading>Mail transport, delivery and user agents</heading>
8329 Debian packages which process electronic mail, whether mail
8330 user agents (MUAs) or mail transport agents (MTAs), must
8331 ensure that they are compatible with the configuration
8332 decisions below. Failure to do this may result in lost
8333 mail, broken <tt>From:</tt> lines, and other serious brain
8338 The mail spool is <file>/var/mail</file> and the interface to
8339 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8340 the FHS). On older systems, the mail spool may be
8341 physically located in <file>/var/spool/mail</file>, but all
8342 access to the mail spool should be via the
8343 <file>/var/mail</file> symlink. The mail spool is part of the
8344 base system and not part of the MTA package.
8348 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8349 programs (such as IMAP daemons) must lock the mailbox in an
8350 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8351 be combined with dot locking. To avoid deadlocks, a program
8352 should use <tt>fcntl()</tt> first and dot locking after
8353 this, or alternatively implement the two locking methods in
8354 a non blocking way<footnote>
8355 If it is not possible to establish both locks, the
8356 system shouldn't wait for the second lock to be
8357 established, but remove the first lock, wait a (random)
8358 time, and start over locking again.
8359 </footnote>. Using the functions <tt>maillock</tt> and
8360 <tt>mailunlock</tt> provided by the
8361 <tt>liblockfile*</tt><footnote>
8362 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8363 to use these functions.
8364 </footnote> packages is the recommended way to realize this.
8368 Mailboxes are generally either mode 600 and owned by
8369 <var>user</var> or mode 660 and owned by
8370 <tt><var>user</var>:mail</tt><footnote>
8371 There are two traditional permission schemes for mail spools:
8372 mode 600 with all mail delivery done by processes running as
8373 the destination user, or mode 660 and owned by group mail with
8374 mail delivery done by a process running as a system user in
8375 group mail. Historically, Debian required mode 660 mail
8376 spools to enable the latter model, but that model has become
8377 increasingly uncommon and the principle of least privilege
8378 indicates that mail systems that use the first model should
8379 use permissions of 600. If delivery to programs is permitted,
8380 it's easier to keep the mail system secure if the delivery
8381 agent runs as the destination user. Debian Policy therefore
8382 permits either scheme.
8383 </footnote>. The local system administrator may choose a
8384 different permission scheme; packages should not make
8385 assumptions about the permission and ownership of mailboxes
8386 unless required (such as when creating a new mailbox). A MUA
8387 may remove a mailbox (unless it has nonstandard permissions) in
8388 which case the MTA or another MUA must recreate it if needed.
8392 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8393 be setgid mail to do the locking mentioned above (and
8394 must obviously avoid accessing other users' mailboxes
8395 using this privilege).</p>
8398 <file>/etc/aliases</file> is the source file for the system mail
8399 aliases (e.g., postmaster, usenet, etc.), it is the one
8400 which the sysadmin and <prgn>postinst</prgn> scripts may
8401 edit. After <file>/etc/aliases</file> is edited the program or
8402 human editing it must call <prgn>newaliases</prgn>. All MTA
8403 packages must come with a <prgn>newaliases</prgn> program,
8404 even if it does nothing, but older MTA packages did not do
8405 this so programs should not fail if <prgn>newaliases</prgn>
8406 cannot be found. Note that because of this, all MTA
8407 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8408 <tt>Replaces: mail-transport-agent</tt> control file
8413 The convention of writing <tt>forward to
8414 <var>address</var></tt> in the mailbox itself is not
8415 supported. Use a <tt>.forward</tt> file instead.</p>
8418 The <prgn>rmail</prgn> program used by UUCP
8419 for incoming mail should be <file>/usr/sbin/rmail</file>.
8420 Likewise, <prgn>rsmtp</prgn>, for receiving
8421 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8425 If your package needs to know what hostname to use on (for
8426 example) outgoing news and mail messages which are generated
8427 locally, you should use the file <file>/etc/mailname</file>. It
8428 will contain the portion after the username and <tt>@</tt>
8429 (at) sign for email addresses of users on the machine
8430 (followed by a newline).
8434 Such a package should check for the existence of this file
8435 when it is being configured. If it exists, it should be
8436 used without comment, although an MTA's configuration script
8437 may wish to prompt the user even if it finds that this file
8438 exists. If the file does not exist, the package should
8439 prompt the user for the value (preferably using
8440 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8441 as well as using it in the package's configuration. The
8442 prompt should make it clear that the name will not just be
8443 used by that package. For example, in this situation the
8444 <tt>inn</tt> package could say something like:
8445 <example compact="compact">
8446 Please enter the "mail name" of your system. This is the
8447 hostname portion of the address to be shown on outgoing
8448 news and mail messages. The default is
8449 <var>syshostname</var>, your system's host name. Mail
8450 name ["<var>syshostname</var>"]:
8452 where <var>syshostname</var> is the output of <tt>hostname
8458 <heading>News system configuration</heading>
8461 All the configuration files related to the NNTP (news)
8462 servers and clients should be located under
8463 <file>/etc/news</file>.</p>
8466 There are some configuration issues that apply to a number
8467 of news clients and server packages on the machine. These
8471 <tag><file>/etc/news/organization</file></tag>
8473 A string which should appear as the
8474 organization header for all messages posted
8475 by NNTP clients on the machine
8478 <tag><file>/etc/news/server</file></tag>
8480 Contains the FQDN of the upstream NNTP
8481 server, or localhost if the local machine is
8486 Other global files may be added as required for cross-package news
8493 <heading>Programs for the X Window System</heading>
8496 <heading>Providing X support and package priorities</heading>
8499 Programs that can be configured with support for the X
8500 Window System must be configured to do so and must declare
8501 any package dependencies necessary to satisfy their
8502 runtime requirements when using the X Window System. If
8503 such a package is of higher priority than the X packages
8504 on which it depends, it is required that either the
8505 X-specific components be split into a separate package, or
8506 that an alternative version of the package, which includes
8507 X support, be provided, or that the package's priority be
8513 <heading>Packages providing an X server</heading>
8516 Packages that provide an X server that, directly or
8517 indirectly, communicates with real input and display
8518 hardware should declare in their control data that they
8519 provide the virtual package <tt>xserver</tt>.<footnote>
8520 This implements current practice, and provides an
8521 actual policy for usage of the <tt>xserver</tt>
8522 virtual package which appears in the virtual packages
8523 list. In a nutshell, X servers that interface
8524 directly with the display and input hardware or via
8525 another subsystem (e.g., GGI) should provide
8526 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8527 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8533 <heading>Packages providing a terminal emulator</heading>
8536 Packages that provide a terminal emulator for the X Window
8537 System which meet the criteria listed below should declare
8538 in their control data that they provide the virtual
8539 package <tt>x-terminal-emulator</tt>. They should also
8540 register themselves as an alternative for
8541 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8546 To be an <tt>x-terminal-emulator</tt>, a program must:
8547 <list compact="compact">
8549 Be able to emulate a DEC VT100 terminal, or a
8550 compatible terminal.
8554 Support the command-line option <tt>-e
8555 <var>command</var></tt>, which creates a new
8556 terminal window<footnote>
8557 "New terminal window" does not necessarily mean
8558 a new top-level X window directly parented by
8559 the window manager; it could, if the terminal
8560 emulator application were so coded, be a new
8561 "view" in a multiple-document interface (MDI).
8563 and runs the specified <var>command</var>,
8564 interpreting the entirety of the rest of the command
8565 line as a command to pass straight to exec, in the
8566 manner that <tt>xterm</tt> does.
8570 Support the command-line option <tt>-T
8571 <var>title</var></tt>, which creates a new terminal
8572 window with the window title <var>title</var>.
8579 <heading>Packages providing a window manager</heading>
8582 Packages that provide a window manager should declare in
8583 their control data that they provide the virtual package
8584 <tt>x-window-manager</tt>. They should also register
8585 themselves as an alternative for
8586 <file>/usr/bin/x-window-manager</file>, with a priority
8587 calculated as follows:
8588 <list compact="compact">
8590 Start with a priority of 20.
8594 If the window manager supports the Debian menu
8595 system, add 20 points if this support is available
8596 in the package's default configuration (i.e., no
8597 configuration files belonging to the system or user
8598 have to be edited to activate the feature); if
8599 configuration files must be modified, add only 10
8605 If the window manager complies with <url
8606 id="http://www.freedesktop.org/Standards/wm-spec"
8607 name="The Window Manager Specification Project">,
8608 written by the <url id="http://www.freedesktop.org/"
8609 name="Free Desktop Group">, add 40 points.
8613 If the window manager permits the X session to be
8614 restarted using a <em>different</em> window manager
8615 (without killing the X server) in its default
8616 configuration, add 10 points; otherwise add none.
8623 <heading>Packages providing fonts</heading>
8626 Packages that provide fonts for the X Window
8628 For the purposes of Debian Policy, a "font for the X
8629 Window System" is one which is accessed via X protocol
8630 requests. Fonts for the Linux console, for PostScript
8631 renderer, or any other purpose, do not fit this
8632 definition. Any tool which makes such fonts available
8633 to the X Window System, however, must abide by this
8636 must do a number of things to ensure that they are both
8637 available without modification of the X or font server
8638 configuration, and that they do not corrupt files used by
8639 other font packages to register information about
8643 Fonts of any type supported by the X Window System
8644 must be in a separate binary package from any
8645 executables, libraries, or documentation (except
8646 that specific to the fonts shipped, such as their
8647 license information). If one or more of the fonts
8648 so packaged are necessary for proper operation of
8649 the package with which they are associated the font
8650 package may be Recommended; if the fonts merely
8651 provide an enhancement, a Suggests relationship may
8652 be used. Packages must not Depend on font
8654 This is because the X server may retrieve fonts
8655 from the local file system or over the network
8656 from an X font server; the Debian package system
8657 is empowered to deal only with the local
8663 BDF fonts must be converted to PCF fonts with the
8664 <prgn>bdftopcf</prgn> utility (available in the
8665 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8666 placed in a directory that corresponds to their
8668 <list compact="compact">
8670 100 dpi fonts must be placed in
8671 <file>/usr/share/fonts/X11/100dpi/</file>.
8675 75 dpi fonts must be placed in
8676 <file>/usr/share/fonts/X11/75dpi/</file>.
8680 Character-cell fonts, cursor fonts, and other
8681 low-resolution fonts must be placed in
8682 <file>/usr/share/fonts/X11/misc/</file>.
8688 Type 1 fonts must be placed in
8689 <file>/usr/share/fonts/X11/Type1/</file>. If font
8690 metric files are available, they must be placed here
8695 Subdirectories of <file>/usr/share/fonts/X11/</file>
8696 other than those listed above must be neither
8697 created nor used. (The <file>PEX</file>, <file>CID</file>,
8698 <file>Speedo</file>, and <file>cyrillic</file> directories
8699 are excepted for historical reasons, but installation of
8700 files into these directories remains discouraged.)
8704 Font packages may, instead of placing files directly
8705 in the X font directories listed above, provide
8706 symbolic links in that font directory pointing to
8707 the files' actual location in the filesystem. Such
8708 a location must comply with the FHS.
8712 Font packages should not contain both 75dpi and
8713 100dpi versions of a font. If both are available,
8714 they should be provided in separate binary packages
8715 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8716 the names of the packages containing the
8717 corresponding fonts.
8721 Fonts destined for the <file>misc</file> subdirectory
8722 should not be included in the same package as 75dpi
8723 or 100dpi fonts; instead, they should be provided in
8724 a separate package with <tt>-misc</tt> appended to
8729 Font packages must not provide the files
8730 <file>fonts.dir</file>, <file>fonts.alias</file>, or
8731 <file>fonts.scale</file> in a font directory:
8734 <file>fonts.dir</file> files must not be provided at all.
8738 <file>fonts.alias</file> and <file>fonts.scale</file>
8739 files, if needed, should be provided in the
8741 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
8742 where <var>fontdir</var> is the name of the
8744 <file>/usr/share/fonts/X11/</file> where the
8745 package's corresponding fonts are stored
8746 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
8747 <var>package</var> is the name of the package
8748 that provides these fonts, and
8749 <var>extension</var> is either <tt>scale</tt>
8750 or <tt>alias</tt>, whichever corresponds to
8757 Font packages must declare a dependency on
8758 <tt>xfonts-utils</tt> in their control
8763 Font packages that provide one or more
8764 <file>fonts.scale</file> files as described above must
8765 invoke <prgn>update-fonts-scale</prgn> on each
8766 directory into which they installed fonts
8767 <em>before</em> invoking
8768 <prgn>update-fonts-dir</prgn> on that directory.
8769 This invocation must occur in both the
8770 <prgn>postinst</prgn> (for all arguments) and
8771 <prgn>postrm</prgn> (for all arguments except
8772 <tt>upgrade</tt>) scripts.
8776 Font packages that provide one or more
8777 <file>fonts.alias</file> files as described above must
8778 invoke <prgn>update-fonts-alias</prgn> on each
8779 directory into which they installed fonts. This
8780 invocation must occur in both the
8781 <prgn>postinst</prgn> (for all arguments) and
8782 <prgn>postrm</prgn> (for all arguments except
8783 <tt>upgrade</tt>) scripts.
8787 Font packages must invoke
8788 <prgn>update-fonts-dir</prgn> on each directory into
8789 which they installed fonts. This invocation must
8790 occur in both the <prgn>postinst</prgn> (for all
8791 arguments) and <prgn>postrm</prgn> (for all
8792 arguments except <tt>upgrade</tt>) scripts.
8796 Font packages must not provide alias names for the
8797 fonts they include which collide with alias names
8798 already in use by fonts already packaged.
8802 Font packages must not provide fonts with the same
8803 XLFD registry name as another font already packaged.
8809 <sect1 id="appdefaults">
8810 <heading>Application defaults files</heading>
8813 Application defaults files must be installed in the
8814 directory <file>/etc/X11/app-defaults/</file> (use of a
8815 localized subdirectory of <file>/etc/X11/</file> as described
8816 in the <em>X Toolkit Intrinsics - C Language
8817 Interface</em> manual is also permitted). They must be
8818 registered as <tt>conffile</tt>s or handled as
8819 configuration files.
8823 Customization of programs' X resources may also be
8824 supported with the provision of a file with the same name
8825 as that of the package placed in
8826 the <file>/etc/X11/Xresources/</file> directory, which
8827 must be registered as a <tt>conffile</tt> or handled as a
8828 configuration file.<footnote>
8829 Note that this mechanism is not the same as using
8830 app-defaults; app-defaults are tied to the client
8831 binary on the local file system, whereas X resources
8832 are stored in the X server and affect all connecting
8839 <heading>Installation directory issues</heading>
8842 Historically, packages using the X Window System used a
8843 separate set of installation directories from other packages.
8844 This practice has been discontinued and packages using the X
8845 Window System should now generally be installed in the same
8846 directories as any other package. Specifically, packages must
8847 not install files under the <file>/usr/X11R6/</file> directory
8848 and the <file>/usr/X11R6/</file> directory hierarchy should be
8849 regarded as obsolete.
8853 Include files previously installed under
8854 <file>/usr/X11R6/include/X11/</file> should be installed into
8855 <file>/usr/include/X11/</file>. For files previously
8856 installed into subdirectories of
8857 <file>/usr/X11R6/lib/X11/</file>, package maintainers should
8858 determine if subdirectories of <file>/usr/lib/</file> and
8859 <file>/usr/share/</file> can be used. If not, a subdirectory
8860 of <file>/usr/lib/X11/</file> should be used.
8864 Configuration files for window, display, or session managers
8865 or other applications that are tightly integrated with the X
8866 Window System may be placed in a subdirectory
8867 of <file>/etc/X11/</file> corresponding to the package name.
8868 Other X Window System applications should use
8869 the <file>/etc/</file> directory unless otherwise mandated by
8870 policy (such as for <ref id="appdefaults">).
8875 <heading>The OSF/Motif and OpenMotif libraries</heading>
8878 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8879 OpenMotif libraries</em><footnote>
8880 OSF/Motif and OpenMotif are collectively referred to as
8881 "Motif" in this policy document.
8883 should be compiled against and tested with LessTif (a free
8884 re-implementation of Motif) instead. If the maintainer
8885 judges that the program or programs do not work
8886 sufficiently well with LessTif to be distributed and
8887 supported, but do so when compiled against Motif, then two
8888 versions of the package should be created; one linked
8889 statically against Motif and with <tt>-smotif</tt>
8890 appended to the package name, and one linked dynamically
8891 against Motif and with <tt>-dmotif</tt> appended to the
8896 Both Motif-linked versions are dependent
8897 upon non-DFSG-compliant software and thus cannot be
8898 uploaded to the <em>main</em> distribution; if the
8899 software is itself DFSG-compliant it may be uploaded to
8900 the <em>contrib</em> distribution. While known existing
8901 versions of Motif permit unlimited redistribution of
8902 binaries linked against the library (whether statically or
8903 dynamically), it is the package maintainer's
8904 responsibility to determine whether this is permitted by
8905 the license of the copy of Motif in their possession.
8911 <heading>Perl programs and modules</heading>
8914 Perl programs and modules should follow the current Perl policy.
8918 The Perl policy can be found in the <tt>perl-policy</tt>
8919 files in the <tt>debian-policy</tt> package.
8920 It is also available from the Debian web mirrors at
8921 <tt><url name="/doc/packaging-manuals/perl-policy/"
8922 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8927 <heading>Emacs lisp programs</heading>
8930 Please refer to the "Debian Emacs Policy" for details of how to
8931 package emacs lisp programs.
8935 The Emacs policy is available in
8936 <file>debian-emacs-policy.gz</file> of the
8937 <package>emacsen-common</package> package.
8938 It is also available from the Debian web mirrors at
8939 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8940 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8945 <heading>Games</heading>
8948 The permissions on <file>/var/games</file> are mode 755, owner
8949 <tt>root</tt> and group <tt>root</tt>.
8953 Each game decides on its own security policy.</p>
8956 Games which require protected, privileged access to
8957 high-score files, saved games, etc., may be made
8958 set-<em>group</em>-id (mode 2755) and owned by
8959 <tt>root:games</tt>, and use files and directories with
8960 appropriate permissions (770 <tt>root:games</tt>, for
8961 example). They must not be made
8962 set-<em>user</em>-id, as this causes security problems. (If
8963 an attacker can subvert any set-user-id game they can
8964 overwrite the executable of any other, causing other players
8965 of these games to run a Trojan horse program. With a
8966 set-group-id game the attacker only gets access to less
8967 important game data, and if they can get at the other
8968 players' accounts at all it will take considerably more
8972 Some packages, for example some fortune cookie programs, are
8973 configured by the upstream authors to install with their
8974 data files or other static information made unreadable so
8975 that they can only be accessed through set-id programs
8976 provided. You should not do this in a Debian package: anyone can
8977 download the <file>.deb</file> file and read the data from it,
8978 so there is no point making the files unreadable. Not
8979 making the files unreadable also means that you don't have
8980 to make so many programs set-id, which reduces the risk of a
8984 As described in the FHS, binaries of games should be
8985 installed in the directory <file>/usr/games</file>. This also
8986 applies to games that use the X Window System. Manual pages
8987 for games (X and non-X games) should be installed in
8988 <file>/usr/share/man/man6</file>.</p>
8994 <heading>Documentation</heading>
8997 <heading>Manual pages</heading>
9000 You should install manual pages in <prgn>nroff</prgn> source
9001 form, in appropriate places under <file>/usr/share/man</file>.
9002 You should only use sections 1 to 9 (see the FHS for more
9003 details). You must not install a pre-formatted "cat page".
9007 Each program, utility, and function should have an
9008 associated manual page included in the same package. It is
9009 suggested that all configuration files also have a manual
9010 page included as well. Manual pages for protocols and other
9011 auxiliary things are optional.
9015 If no manual page is available, this is considered as a bug
9016 and should be reported to the Debian Bug Tracking System (the
9017 maintainer of the package is allowed to write this bug report
9018 themselves, if they so desire). Do not close the bug report
9019 until a proper man page is available.<footnote>
9020 It is not very hard to write a man page. See the
9021 <url id="http://www.schweikhardt.net/man_page_howto.html"
9022 name="Man-Page-HOWTO">,
9023 <manref name="man" section="7">, the examples
9024 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
9025 the helper program <prgn>help2man</prgn>, or the
9026 directory <file>/usr/share/doc/man-db/examples</file>.
9031 You may forward a complaint about a missing man page to the
9032 upstream authors, and mark the bug as forwarded in the
9033 Debian bug tracking system. Even though the GNU Project do
9034 not in general consider the lack of a man page to be a bug,
9035 we do; if they tell you that they don't consider it a bug
9036 you should leave the bug in our bug tracking system open
9041 Manual pages should be installed compressed using <tt>gzip -9</tt>.
9045 If one man page needs to be accessible via several names it
9046 is better to use a symbolic link than the <file>.so</file>
9047 feature, but there is no need to fiddle with the relevant
9048 parts of the upstream source to change from <file>.so</file> to
9049 symlinks: don't do it unless it's easy. You should not
9050 create hard links in the manual page directories, nor put
9051 absolute filenames in <file>.so</file> directives. The filename
9052 in a <file>.so</file> in a man page should be relative to the
9053 base of the man page tree (usually
9054 <file>/usr/share/man</file>). If you do not create any links
9055 (whether symlinks, hard links, or <tt>.so</tt> directives)
9056 in the file system to the alternate names of the man page,
9057 then you should not rely on <prgn>man</prgn> finding your
9058 man page under those names based solely on the information in
9059 the man page's header.<footnote>
9060 Supporting this in <prgn>man</prgn> often requires
9061 unreasonable processing time to find a manual page or to
9062 report that none exists, and moves knowledge into man's
9063 database that would be better left in the file system.
9064 This support is therefore deprecated and will cease to
9065 be present in the future.
9070 Manual pages in locale-specific subdirectories of
9071 <file>/usr/share/man</file> should use either UTF-8 or the usual
9072 legacy encoding for that language (normally the one corresponding
9073 to the shortest relevant locale name in
9074 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
9075 <file>/usr/share/man/fr</file> should use either UTF-8 or
9076 ISO-8859-1.<footnote>
9077 <prgn>man</prgn> will automatically detect whether UTF-8 is in
9078 use. In future, all manual pages will be required to use
9084 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
9085 included in the subdirectory name unless it indicates a
9086 significant difference in the language, as this excludes
9087 speakers of the language in other countries.<footnote>
9088 At the time of writing, Chinese and Portuguese are the main
9089 languages with such differences, so <file>pt_BR</file>,
9090 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
9095 If a localized version of a manual page is provided, it should
9096 either be up-to-date or it should be obvious to the reader that
9097 it is outdated and the original manual page should be used
9098 instead. This can be done either by a note at the beginning of
9099 the manual page or by showing the missing or changed portions in
9100 the original language instead of the target language.
9105 <heading>Info documents</heading>
9108 Info documents should be installed in <file>/usr/share/info</file>.
9109 They should be compressed with <tt>gzip -9</tt>.
9113 The <prgn>install-info</prgn> program maintains a directory of
9114 installed info documents in <file>/usr/share/info/dir</file> for
9115 the use of info readers.<footnote>
9116 It was previously necessary for packages installing info
9117 documents to run <prgn>install-info</prgn> from maintainer
9118 scripts. This is no longer necessary. The installation
9119 system now uses dpkg triggers.
9121 This file must not be included in packages. Packages containing
9122 info documents should depend on <tt>dpkg (>= 1.15.4) |
9123 install-info</tt> to ensure that the directory file is properly
9124 rebuilt during partial upgrades from Debian 5.0 (lenny) and
9129 Info documents should contain section and directory entry
9130 information in the document for the use
9131 of <prgn>install-info</prgn>. The section should be specified
9132 via a line starting with <tt>INFO-DIR-SECTION</tt> followed by a
9133 space and the section of this info page. The directory entry or
9134 entries should be included between
9135 a <tt>START-INFO-DIR-ENTRY</tt> line and
9136 an <tt>END-INFO-DIR-ENTRY</tt> line. For example:
9138 INFO-DIR-SECTION Individual utilities
9139 START-INFO-DIR-ENTRY
9140 * example: (example). An example info directory entry.
9143 To determine which section to use, you should look
9144 at <file>/usr/share/info/dir</file> on your system and choose
9145 the most relevant (or create a new section if none of the
9146 current sections are relevant).<footnote>
9147 Normally, info documents are generated from Texinfo source.
9148 To include this information in the generated info document, if
9149 it is absent, add commands like:
9151 @dircategory Individual utilities
9153 * example: (example). An example info directory entry.
9156 to the Texinfo source of the document and ensure that the info
9157 documents are rebuilt from source during the package build.
9163 <heading>Additional documentation</heading>
9166 Any additional documentation that comes with the package may
9167 be installed at the discretion of the package maintainer.
9168 Plain text documentation should be installed in the directory
9169 <file>/usr/share/doc/<var>package</var></file>, where
9170 <var>package</var> is the name of the package, and
9171 compressed with <tt>gzip -9</tt> unless it is small.
9175 If a package comes with large amounts of documentation which
9176 many users of the package will not require you should create
9177 a separate binary package to contain it, so that it does not
9178 take up disk space on the machines of users who do not need
9179 or want it installed.</p>
9182 It is often a good idea to put text information files
9183 (<file>README</file>s, changelogs, and so forth) that come with
9184 the source package in <file>/usr/share/doc/<var>package</var></file>
9185 in the binary package. However, you don't need to install
9186 the instructions for building and installing the package, of
9190 Packages must not require the existence of any files in
9191 <file>/usr/share/doc/</file> in order to function
9193 The system administrator should be able to
9194 delete files in <file>/usr/share/doc/</file> without causing
9195 any programs to break.
9197 Any files that are referenced by programs but are also
9198 useful as stand alone documentation should be installed under
9199 <file>/usr/share/<var>package</var>/</file> with symbolic links from
9200 <file>/usr/share/doc/<var>package</var></file>.
9204 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9205 link to another directory in <file>/usr/share/doc</file> only if
9206 the two packages both come from the same source and the
9207 first package Depends on the second.<footnote>
9209 Please note that this does not override the section on
9210 changelog files below, so the file
9211 <file>/usr/share/doc/<var>package</var>/changelog.Debian.gz</file>
9212 must refer to the changelog for the current version of
9213 <var>package</var> in question. In practice, this means
9214 that the sources of the target and the destination of the
9215 symlink must be the same (same source package and
9222 Former Debian releases placed all additional documentation
9223 in <file>/usr/doc/<var>package</var></file>. This has been
9224 changed to <file>/usr/share/doc/<var>package</var></file>,
9225 and packages must not put documentation in the directory
9226 <file>/usr/doc/<var>package</var></file>. <footnote>
9227 At this phase of the transition, we no longer require a
9228 symbolic link in <file>/usr/doc/</file>. At a later point,
9229 policy shall change to make the symbolic links a bug.
9235 <heading>Preferred documentation formats</heading>
9238 The unification of Debian documentation is being carried out
9242 If your package comes with extensive documentation in a
9243 markup format that can be converted to various other formats
9244 you should if possible ship HTML versions in a binary
9245 package, in the directory
9246 <file>/usr/share/doc/<var>appropriate-package</var></file> or
9247 its subdirectories.<footnote>
9248 The rationale: The important thing here is that HTML
9249 docs should be available in <em>some</em> package, not
9250 necessarily in the main binary package.
9255 Other formats such as PostScript may be provided at the
9256 package maintainer's discretion.
9260 <sect id="copyrightfile">
9261 <heading>Copyright information</heading>
9264 Every package must be accompanied by a verbatim copy of its
9265 copyright information and distribution license in the file
9266 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
9267 file must neither be compressed nor be a symbolic link.
9271 In addition, the copyright file must say where the upstream
9272 sources (if any) were obtained. It should name the original
9273 authors of the package and the Debian maintainer(s) who were
9274 involved with its creation.
9278 Packages in the <em>contrib</em> or <em>non-free</em> archive
9279 areas should state in the copyright file that the package is not
9280 part of the Debian GNU/Linux distribution and briefly explain
9285 A copy of the file which will be installed in
9286 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9287 be in <file>debian/copyright</file> in the source package.
9291 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9292 link to another directory in <file>/usr/share/doc</file> only if
9293 the two packages both come from the same source and the
9294 first package Depends on the second. These rules are
9295 important because copyrights must be extractable by
9300 Packages distributed under the Apache license (version 2.0), the
9301 Artistic license, the GNU GPL (version 2 or 3), the GNU LGPL
9302 (versions 2, 2.1, or 3), and the GNU FDL (versions 1.2 or 1.3)
9303 should refer to the corresponding files
9304 under <file>/usr/share/common-licenses</file>,<footnote>
9307 <file>/usr/share/common-licenses/Apache-2.0</file>,
9308 <file>/usr/share/common-licenses/Artistic</file>,
9309 <file>/usr/share/common-licenses/GPL-2</file>,
9310 <file>/usr/share/common-licenses/GPL-3</file>,
9311 <file>/usr/share/common-licenses/LGPL-2</file>,
9312 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9313 <file>/usr/share/common-licenses/LGPL-3</file>,
9314 <file>/usr/share/common-licenses/GFDL-1.2</file>, and
9315 <file>/usr/share/common-licenses/GFDL-1.3</file>
9316 respectively. The University of California BSD license is
9317 also included in <package>base-files</package> as
9318 <file>/usr/share/common-licenses/BSD</file>, but given the
9319 brevity of this license, its specificity to code whose
9320 copyright is held by the Regents of the University of
9321 California, and the frequency of minor wording changes, its
9322 text should be included in the copyright file rather than
9323 referencing this file.
9325 </footnote> rather than quoting them in the copyright
9330 You should not use the copyright file as a general <file>README</file>
9331 file. If your package has such a file it should be
9332 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9333 <file>README.Debian</file> or some other appropriate place.</p>
9337 <heading>Examples</heading>
9340 Any examples (configurations, source files, whatever),
9341 should be installed in a directory
9342 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9343 files should not be referenced by any program: they're there
9344 for the benefit of the system administrator and users as
9345 documentation only. Architecture-specific example files
9346 should be installed in a directory
9347 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9349 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9350 latter directory itself may be a symbolic link to the
9355 If the purpose of a package is to provide examples, then the
9356 example files may be installed into
9357 <file>/usr/share/doc/<var>package</var></file>.
9361 <sect id="changelogs">
9362 <heading>Changelog files</heading>
9365 Packages that are not Debian-native must contain a
9366 compressed copy of the <file>debian/changelog</file> file from
9367 the Debian source tree in
9368 <file>/usr/share/doc/<var>package</var></file> with the name
9369 <file>changelog.Debian.gz</file>.
9373 If an upstream changelog is available, it should be accessible as
9374 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9375 plain text. If the upstream changelog is distributed in
9376 HTML, it should be made available in that form as
9377 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9378 and a plain text <file>changelog.gz</file> should be generated
9379 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9380 the upstream changelog files do not already conform to this
9381 naming convention, then this may be achieved either by
9382 renaming the files, or by adding a symbolic link, at the
9383 maintainer's discretion.<footnote>
9384 Rationale: People should not have to look in places for
9385 upstream changelogs merely because they are given
9386 different names or are distributed in HTML format.
9391 All of these files should be installed compressed using
9392 <tt>gzip -9</tt>, as they will become large with time even
9393 if they start out small.
9397 If the package has only one changelog which is used both as
9398 the Debian changelog and the upstream one because there is
9399 no separate upstream maintainer then that changelog should
9400 usually be installed as
9401 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9402 there is a separate upstream maintainer, but no upstream
9403 changelog, then the Debian changelog should still be called
9404 <file>changelog.Debian.gz</file>.
9408 For details about the format and contents of the Debian
9409 changelog file, please see <ref id="dpkgchangelog">.
9414 <appendix id="pkg-scope">
9415 <heading>Introduction and scope of these appendices</heading>
9418 These appendices are taken essentially verbatim from the
9419 now-deprecated Packaging Manual, version 3.2.1.0. They are
9420 the chapters which are likely to be of use to package
9421 maintainers and which have not already been included in the
9422 policy document itself. Most of these sections are very likely
9423 not relevant to policy; they should be treated as
9424 documentation for the packaging system. Please note that these
9425 appendices are included for convenience, and for historical
9426 reasons: they used to be part of policy package, and they have
9427 not yet been incorporated into dpkg documentation. However,
9428 they still have value, and hence they are presented here.
9432 They have not yet been checked to ensure that they are
9433 compatible with the contents of policy, and if there are any
9434 contradictions, the version in the main policy document takes
9435 precedence. The remaining chapters of the old Packaging
9436 Manual have also not been read in detail to ensure that there
9437 are not parts which have been left out. Both of these will be
9442 Certain parts of the Packaging manual were integrated into the
9443 Policy Manual proper, and removed from the appendices. Links
9444 have been placed from the old locations to the new ones.
9448 <prgn>dpkg</prgn> is a suite of programs for creating binary
9449 package files and installing and removing them on Unix
9451 <prgn>dpkg</prgn> is targeted primarily at Debian
9452 GNU/Linux, but may work on or be ported to other
9458 The binary packages are designed for the management of
9459 installed executable programs (usually compiled binaries) and
9460 their associated data, though source code examples and
9461 documentation are provided as part of some packages.</p>
9464 This manual describes the technical aspects of creating Debian
9465 binary packages (<file>.deb</file> files). It documents the
9466 behavior of the package management programs
9467 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9468 they interact with packages.</p>
9471 It also documents the interaction between
9472 <prgn>dselect</prgn>'s core and the access method scripts it
9473 uses to actually install the selected packages, and describes
9474 how to create a new access method.</p>
9477 This manual does not go into detail about the options and
9478 usage of the package building and installation tools. It
9479 should therefore be read in conjunction with those programs'
9484 The utility programs which are provided with <prgn>dpkg</prgn>
9485 for managing various system configuration and similar issues,
9486 such as <prgn>update-rc.d</prgn> and
9487 <prgn>install-info</prgn>, are not described in detail here -
9488 please see their man pages.
9492 It is assumed that the reader is reasonably familiar with the
9493 <prgn>dpkg</prgn> System Administrators' manual.
9494 Unfortunately this manual does not yet exist.
9498 The Debian version of the FSF's GNU hello program is provided
9499 as an example for people wishing to create Debian
9500 packages. The Debian <prgn>debmake</prgn> package is
9501 recommended as a very helpful tool in creating and maintaining
9502 Debian packages. However, while the tools and examples are
9503 helpful, they do not replace the need to read and follow the
9504 Policy and Programmer's Manual.</p>
9507 <appendix id="pkg-binarypkg">
9508 <heading>Binary packages (from old Packaging Manual)</heading>
9511 The binary package has two main sections. The first part
9512 consists of various control information files and scripts used
9513 by <prgn>dpkg</prgn> when installing and removing. See <ref
9514 id="pkg-controlarea">.
9518 The second part is an archive containing the files and
9519 directories to be installed.
9523 In the future binary packages may also contain other
9524 components, such as checksums and digital signatures. The
9525 format for the archive is described in full in the
9526 <file>deb(5)</file> man page.
9530 <sect id="pkg-bincreating"><heading>Creating package files -
9531 <prgn>dpkg-deb</prgn>
9535 All manipulation of binary package files is done by
9536 <prgn>dpkg-deb</prgn>; it's the only program that has
9537 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9538 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9539 will spot that the options requested are appropriate to
9540 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9545 In order to create a binary package you must make a
9546 directory tree which contains all the files and directories
9547 you want to have in the file system data part of the package.
9548 In Debian-format source packages this directory is usually
9549 <file>debian/tmp</file>, relative to the top of the package's
9554 They should have the locations (relative to the root of the
9555 directory tree you're constructing) ownerships and
9556 permissions which you want them to have on the system when
9561 With current versions of <prgn>dpkg</prgn> the uid/username
9562 and gid/groupname mappings for the users and groups being
9563 used should be the same on the system where the package is
9564 built and the one where it is installed.
9568 You need to add one special directory to the root of the
9569 miniature file system tree you're creating:
9570 <prgn>DEBIAN</prgn>. It should contain the control
9571 information files, notably the binary package control file
9572 (see <ref id="pkg-controlfile">).
9576 The <prgn>DEBIAN</prgn> directory will not appear in the
9577 file system archive of the package, and so won't be installed
9578 by <prgn>dpkg</prgn> when the package is installed.
9582 When you've prepared the package, you should invoke:
9584 dpkg --build <var>directory</var>
9589 This will build the package in
9590 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9591 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9592 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9597 See the man page <manref name="dpkg-deb" section="8"> for details of how
9598 to examine the contents of this newly-created file. You may find the
9599 output of following commands enlightening:
9601 dpkg-deb --info <var>filename</var>.deb
9602 dpkg-deb --contents <var>filename</var>.deb
9603 dpkg --contents <var>filename</var>.deb
9605 To view the copyright file for a package you could use this command:
9607 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
9612 <sect id="pkg-controlarea">
9613 <heading>Package control information files</heading>
9616 The control information portion of a binary package is a
9617 collection of files with names known to <prgn>dpkg</prgn>.
9618 It will treat the contents of these files specially - some
9619 of them contain information used by <prgn>dpkg</prgn> when
9620 installing or removing the package; others are scripts which
9621 the package maintainer wants <prgn>dpkg</prgn> to run.
9625 It is possible to put other files in the package control
9626 area, but this is not generally a good idea (though they
9627 will largely be ignored).
9631 Here is a brief list of the control info files supported by
9632 <prgn>dpkg</prgn> and a summary of what they're used for.
9637 <tag><tt>control</tt>
9640 This is the key description file used by
9641 <prgn>dpkg</prgn>. It specifies the package's name
9642 and version, gives its description for the user,
9643 states its relationships with other packages, and so
9644 forth. See <ref id="sourcecontrolfiles"> and
9645 <ref id="binarycontrolfiles">.
9649 It is usually generated automatically from information
9650 in the source package by the
9651 <prgn>dpkg-gencontrol</prgn> program, and with
9652 assistance from <prgn>dpkg-shlibdeps</prgn>.
9653 See <ref id="pkg-sourcetools">.
9657 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9662 These are executable files (usually scripts) which
9663 <prgn>dpkg</prgn> runs during installation, upgrade
9664 and removal of packages. They allow the package to
9665 deal with matters which are particular to that package
9666 or require more complicated processing than that
9667 provided by <prgn>dpkg</prgn>. Details of when and
9668 how they are called are in <ref id="maintainerscripts">.
9672 It is very important to make these scripts idempotent.
9673 See <ref id="idempotency">.
9677 The maintainer scripts are not guaranteed to run with a
9678 controlling terminal and may not be able to interact with
9679 the user. See <ref id="controllingterminal">.
9683 <tag><tt>conffiles</tt>
9686 This file contains a list of configuration files which
9687 are to be handled automatically by <prgn>dpkg</prgn>
9688 (see <ref id="pkg-conffiles">). Note that not necessarily
9689 every configuration file should be listed here.
9692 <tag><tt>shlibs</tt>
9695 This file contains a list of the shared libraries
9696 supplied by the package, with dependency details for
9697 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9698 when it determines what dependencies are required in a
9699 package control file. The <tt>shlibs</tt> file format
9700 is described on <ref id="shlibs">.
9705 <sect id="pkg-controlfile">
9706 <heading>The main control information file: <tt>control</tt></heading>
9709 The most important control information file used by
9710 <prgn>dpkg</prgn> when it installs a package is
9711 <tt>control</tt>. It contains all the package's "vital
9716 The binary package control files of packages built from
9717 Debian sources are made by a special tool,
9718 <prgn>dpkg-gencontrol</prgn>, which reads
9719 <file>debian/control</file> and <file>debian/changelog</file> to
9720 find the information it needs. See <ref id="pkg-sourcepkg"> for
9725 The fields in binary package control files are listed in
9726 <ref id="binarycontrolfiles">.
9730 A description of the syntax of control files and the purpose
9731 of the fields is available in <ref id="controlfields">.
9736 <heading>Time Stamps</heading>
9739 See <ref id="timestamps">.
9744 <appendix id="pkg-sourcepkg">
9745 <heading>Source packages (from old Packaging Manual) </heading>
9748 The Debian binary packages in the distribution are generated
9749 from Debian sources, which are in a special format to assist
9750 the easy and automatic building of binaries.
9753 <sect id="pkg-sourcetools">
9754 <heading>Tools for processing source packages</heading>
9757 Various tools are provided for manipulating source packages;
9758 they pack and unpack sources and help build of binary
9759 packages and help manage the distribution of new versions.
9763 They are introduced and typical uses described here; see
9764 <manref name="dpkg-source" section="1"> for full
9765 documentation about their arguments and operation.
9769 For examples of how to construct a Debian source package,
9770 and how to use those utilities that are used by Debian
9771 source packages, please see the <prgn>hello</prgn> example
9775 <sect1 id="pkg-dpkg-source">
9777 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
9782 This program is frequently used by hand, and is also
9783 called from package-independent automated building scripts
9784 such as <prgn>dpkg-buildpackage</prgn>.
9788 To unpack a package it is typically invoked with
9790 dpkg-source -x <var>.../path/to/filename</var>.dsc
9795 with the <file><var>filename</var>.tar.gz</file> and
9796 <file><var>filename</var>.diff.gz</file> (if applicable) in
9797 the same directory. It unpacks into
9798 <file><var>package</var>-<var>version</var></file>, and if
9800 <file><var>package</var>-<var>version</var>.orig</file>, in
9801 the current directory.
9805 To create a packed source archive it is typically invoked:
9807 dpkg-source -b <var>package</var>-<var>version</var>
9812 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
9813 <file>.diff.gz</file> (if appropriate) in the current
9814 directory. <prgn>dpkg-source</prgn> does not clean the
9815 source tree first - this must be done separately if it is
9820 See also <ref id="pkg-sourcearchives">.</p>
9824 <sect1 id="pkg-dpkg-buildpackage">
9826 <prgn>dpkg-buildpackage</prgn> - overall package-building
9831 <prgn>dpkg-buildpackage</prgn> is a script which invokes
9832 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
9833 targets <tt>clean</tt>, <tt>build</tt> and
9834 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
9835 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
9836 source and binary package upload.
9840 It is usually invoked by hand from the top level of the
9841 built or unbuilt source directory. It may be invoked with
9842 no arguments; useful arguments include:
9843 <taglist compact="compact">
9844 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
9847 Do not sign the <tt>.changes</tt> file or the
9848 source package <tt>.dsc</tt> file, respectively.</p>
9850 <tag><tt>-p<var>sign-command</var></tt></tag>
9853 Invoke <var>sign-command</var> instead of finding
9854 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
9855 <var>sign-command</var> must behave just like
9856 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9858 <tag><tt>-r<var>root-command</var></tt></tag>
9861 When root privilege is required, invoke the command
9862 <var>root-command</var>. <var>root-command</var>
9863 should invoke its first argument as a command, from
9864 the <prgn>PATH</prgn> if necessary, and pass its
9865 second and subsequent arguments to the command it
9866 calls. If no <var>root-command</var> is supplied
9867 then <var>dpkg-buildpackage</var> will take no
9868 special action to gain root privilege, so that for
9869 most packages it will have to be invoked as root to
9872 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9875 Two types of binary-only build and upload - see
9876 <manref name="dpkg-source" section="1">.
9883 <sect1 id="pkg-dpkg-gencontrol">
9885 <prgn>dpkg-gencontrol</prgn> - generates binary package
9890 This program is usually called from <file>debian/rules</file>
9891 (see <ref id="pkg-sourcetree">) in the top level of the source
9896 This is usually done just before the files and directories in the
9897 temporary directory tree where the package is being built have their
9898 permissions and ownerships set and the package is constructed using
9899 <prgn>dpkg-deb/</prgn>
9901 This is so that the control file which is produced has
9902 the right permissions
9907 <prgn>dpkg-gencontrol</prgn> must be called after all the
9908 files which are to go into the package have been placed in
9909 the temporary build directory, so that its calculation of
9910 the installed size of a package is correct.
9914 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9915 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9916 variable substitutions created by
9917 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9922 For a package which generates only one binary package, and
9923 which builds it in <file>debian/tmp</file> relative to the top
9924 of the source package, it is usually sufficient to call
9925 <prgn>dpkg-gencontrol</prgn>.
9929 Sources which build several binaries will typically need
9932 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9933 </example> The <tt>-P</tt> tells
9934 <prgn>dpkg-gencontrol</prgn> that the package is being
9935 built in a non-default directory, and the <tt>-p</tt>
9936 tells it which package's control file should be generated.
9940 <prgn>dpkg-gencontrol</prgn> also adds information to the
9941 list of files in <file>debian/files</file>, for the benefit of
9942 (for example) a future invocation of
9943 <prgn>dpkg-genchanges</prgn>.</p>
9946 <sect1 id="pkg-dpkg-shlibdeps">
9948 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9953 This program is usually called from <file>debian/rules</file>
9954 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9955 id="pkg-sourcetree">), in the top level of the source tree.
9959 Its arguments are executables and shared libraries
9962 They may be specified either in the locations in the
9963 source tree where they are created or in the locations
9964 in the temporary build tree where they are installed
9965 prior to binary package creation.
9967 </footnote> for which shared library dependencies should
9968 be included in the binary package's control file.
9972 If some of the found shared libraries should only
9973 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9974 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9975 by using the <tt>-d<var>dependency-field</var></tt> option
9976 before those executable(s). (Each <tt>-d</tt> option
9977 takes effect until the next <tt>-d</tt>.)
9981 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9982 output control file to be modified. Instead by default it
9983 adds to the <file>debian/substvars</file> file variable
9984 settings like <tt>shlibs:Depends</tt>. These variable
9985 settings must be referenced in dependency fields in the
9986 appropriate per-binary-package sections of the source
9991 For example, a package that generates an essential part
9992 which requires dependencies, and optional parts that
9993 which only require a recommendation, would separate those
9994 two sets of dependencies into two different fields.<footnote>
9995 At the time of writing, an example for this was the
9996 <package/xmms/ package, with Depends used for the xmms
9997 executable, Recommends for the plug-ins and Suggests for
9998 even more optional features provided by unzip.
10000 It can say in its <file>debian/rules</file>:
10002 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
10003 -dRecommends <var>optionalpart anotheroptionalpart</var>
10005 and then in its main control file <file>debian/control</file>:
10008 Depends: ${shlibs:Depends}
10009 Recommends: ${shlibs:Recommends}
10015 Sources which produce several binary packages with
10016 different shared library dependency requirements can use
10017 the <tt>-p<var>varnameprefix</var></tt> option to override
10018 the default <tt>shlibs:</tt> prefix (one invocation of
10019 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
10020 They can thus produce several sets of dependency
10021 variables, each of the form
10022 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
10023 which can be referred to in the appropriate parts of the
10024 binary package control files.
10029 <sect1 id="pkg-dpkg-distaddfile">
10031 <prgn>dpkg-distaddfile</prgn> - adds a file to
10032 <file>debian/files</file>
10036 Some packages' uploads need to include files other than
10037 the source and binary package files.
10041 <prgn>dpkg-distaddfile</prgn> adds a file to the
10042 <file>debian/files</file> file so that it will be included in
10043 the <file>.changes</file> file when
10044 <prgn>dpkg-genchanges</prgn> is run.
10048 It is usually invoked from the <tt>binary</tt> target of
10049 <file>debian/rules</file>:
10051 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
10053 The <var>filename</var> is relative to the directory where
10054 <prgn>dpkg-genchanges</prgn> will expect to find it - this
10055 is usually the directory above the top level of the source
10056 tree. The <file>debian/rules</file> target should put the
10057 file there just before or just after calling
10058 <prgn>dpkg-distaddfile</prgn>.
10062 The <var>section</var> and <var>priority</var> are passed
10063 unchanged into the resulting <file>.changes</file> file.
10068 <sect1 id="pkg-dpkg-genchanges">
10070 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
10071 upload control file
10075 This program is usually called by package-independent
10076 automatic building scripts such as
10077 <prgn>dpkg-buildpackage</prgn>, but it may also be called
10082 It is usually called in the top level of a built source
10083 tree, and when invoked with no arguments will print out a
10084 straightforward <file>.changes</file> file based on the
10085 information in the source package's changelog and control
10086 file and the binary and source packages which should have
10092 <sect1 id="pkg-dpkg-parsechangelog">
10094 <prgn>dpkg-parsechangelog</prgn> - produces parsed
10095 representation of a changelog
10099 This program is used internally by
10100 <prgn>dpkg-source</prgn> et al. It may also occasionally
10101 be useful in <file>debian/rules</file> and elsewhere. It
10102 parses a changelog, <file>debian/changelog</file> by default,
10103 and prints a control-file format representation of the
10104 information in it to standard output.
10108 <sect1 id="pkg-dpkg-architecture">
10110 <prgn>dpkg-architecture</prgn> - information about the build and
10115 This program can be used manually, but is also invoked by
10116 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
10117 environment or make variables which specify the build and host
10118 architecture for the package building process.
10123 <sect id="pkg-sourcetree">
10124 <heading>The Debianised source tree</heading>
10127 The source archive scheme described later is intended to
10128 allow a Debianised source tree with some associated control
10129 information to be reproduced and transported easily. The
10130 Debianised source tree is a version of the original program
10131 with certain files added for the benefit of the
10132 Debianisation process, and with any other changes required
10133 made to the rest of the source code and installation
10138 The extra files created for Debian are in the subdirectory
10139 <file>debian</file> of the top level of the Debianised source
10140 tree. They are described below.
10143 <sect1 id="pkg-debianrules">
10144 <heading><file>debian/rules</file> - the main building script</heading>
10147 See <ref id="debianrules">.
10151 <sect1 id="pkg-srcsubstvars">
10152 <heading><file>debian/substvars</file> and variable substitutions</heading>
10155 See <ref id="substvars">.
10161 <heading><file>debian/files</file></heading>
10164 See <ref id="debianfiles">.
10168 <sect1><heading><file>debian/tmp</file>
10172 This is the canonical temporary location for the
10173 construction of binary packages by the <tt>binary</tt>
10174 target. The directory <file>tmp</file> serves as the root of
10175 the file system tree as it is being constructed (for
10176 example, by using the package's upstream makefiles install
10177 targets and redirecting the output there), and it also
10178 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10179 id="pkg-bincreating">.
10183 If several binary packages are generated from the same
10184 source tree it is usual to use several
10185 <file>debian/tmp<var>something</var></file> directories, for
10186 example <file>tmp-a</file> or <file>tmp-doc</file>.
10190 Whatever <file>tmp</file> directories are created and used by
10191 <tt>binary</tt> must of course be removed by the
10192 <tt>clean</tt> target.</p></sect1>
10196 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10200 As it exists on the FTP site, a Debian source package
10201 consists of three related files. You must have the right
10202 versions of all three to be able to use them.
10207 <tag>Debian source control file - <tt>.dsc</tt></tag>
10209 This file is a control file used by <prgn>dpkg-source</prgn>
10210 to extract a source package.
10211 See <ref id="debiansourcecontrolfiles">.
10215 Original source archive -
10217 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10223 This is a compressed (with <tt>gzip -9</tt>)
10224 <prgn>tar</prgn> file containing the source code from
10225 the upstream authors of the program.
10230 Debianisation diff -
10232 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10238 This is a unified context diff (<tt>diff -u</tt>)
10239 giving the changes which are required to turn the
10240 original source into the Debian source. These changes
10241 may only include editing and creating plain files.
10242 The permissions of files, the targets of symbolic
10243 links and the characteristics of special files or
10244 pipes may not be changed and no files may be removed
10249 All the directories in the diff must exist, except the
10250 <file>debian</file> subdirectory of the top of the source
10251 tree, which will be created by
10252 <prgn>dpkg-source</prgn> if necessary when unpacking.
10256 The <prgn>dpkg-source</prgn> program will
10257 automatically make the <file>debian/rules</file> file
10258 executable (see below).</p></item>
10263 If there is no original source code - for example, if the
10264 package is specially prepared for Debian or the Debian
10265 maintainer is the same as the upstream maintainer - the
10266 format is slightly different: then there is no diff, and the
10268 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10269 and preferably contains a directory named
10270 <file><var>package</var>-<var>version</var></file>.
10275 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10278 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10279 Debian source package. However, if it is not available it
10280 is possible to unpack a Debian source archive as follows:
10281 <enumlist compact="compact">
10284 Untar the tarfile, which will create a <file>.orig</file>
10288 <p>Rename the <file>.orig</file> directory to
10289 <file><var>package</var>-<var>version</var></file>.</p>
10293 Create the subdirectory <file>debian</file> at the top of
10294 the source tree.</p>
10296 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10298 <item><p>Untar the tarfile again if you want a copy of the original
10299 source code alongside the Debianised version.</p>
10304 It is not possible to generate a valid Debian source archive
10305 without using <prgn>dpkg-source</prgn>. In particular,
10306 attempting to use <prgn>diff</prgn> directly to generate the
10307 <file>.diff.gz</file> file will not work.
10311 <heading>Restrictions on objects in source packages</heading>
10314 The source package may not contain any hard links
10316 This is not currently detected when building source
10317 packages, but only when extracting
10321 Hard links may be permitted at some point in the
10322 future, but would require a fair amount of
10324 </footnote>, device special files, sockets or setuid or
10327 Setgid directories are allowed.
10332 The source packaging tools manage the changes between the
10333 original and Debianised source using <prgn>diff</prgn> and
10334 <prgn>patch</prgn>. Turning the original source tree as
10335 included in the <file>.orig.tar.gz</file> into the debianised
10336 source must not involve any changes which cannot be
10337 handled by these tools. Problematic changes which cause
10338 <prgn>dpkg-source</prgn> to halt with an error when
10339 building the source package are:
10340 <list compact="compact">
10341 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10343 <item><p>Changing the targets of symbolic links.</p>
10345 <item><p>Creating directories, other than <file>debian</file>.</p>
10347 <item><p>Changes to the contents of binary files.</p></item>
10348 </list> Changes which cause <prgn>dpkg-source</prgn> to
10349 print a warning but continue anyway are:
10350 <list compact="compact">
10353 Removing files, directories or symlinks.
10355 Renaming a file is not treated specially - it is
10356 seen as the removal of the old file (which
10357 generates a warning, but is otherwise ignored),
10358 and the creation of the new one.
10364 Changed text files which are missing the usual final
10365 newline (either in the original or the modified
10370 Changes which are not represented, but which are not detected by
10371 <prgn>dpkg-source</prgn>, are:
10372 <list compact="compact">
10373 <item><p>Changing the permissions of files (other than
10374 <file>debian/rules</file>) and directories.</p></item>
10379 The <file>debian</file> directory and <file>debian/rules</file>
10380 are handled specially by <prgn>dpkg-source</prgn> - before
10381 applying the changes it will create the <file>debian</file>
10382 directory, and afterwards it will make
10383 <file>debian/rules</file> world-executable.
10389 <appendix id="pkg-controlfields">
10390 <heading>Control files and their fields (from old Packaging Manual)</heading>
10393 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10394 data in a common format, known as control files. Binary and
10395 source packages have control data as do the <file>.changes</file>
10396 files which control the installation of uploaded files, and
10397 <prgn>dpkg</prgn>'s internal databases are in a similar
10402 <heading>Syntax of control files</heading>
10405 See <ref id="controlsyntax">.
10409 It is important to note that there are several fields which
10410 are optional as far as <prgn>dpkg</prgn> and the related
10411 tools are concerned, but which must appear in every Debian
10412 package, or whose omission may cause problems.
10417 <heading>List of fields</heading>
10420 See <ref id="controlfieldslist">.
10424 This section now contains only the fields that didn't belong
10425 to the Policy manual.
10428 <sect1 id="pkg-f-Filename">
10429 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10432 These fields in <tt>Packages</tt> files give the
10433 filename(s) of (the parts of) a package in the
10434 distribution directories, relative to the root of the
10435 Debian hierarchy. If the package has been split into
10436 several parts the parts are all listed in order, separated
10441 <sect1 id="pkg-f-Size">
10442 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10445 These fields in <file>Packages</file> files give the size (in
10446 bytes, expressed in decimal) and MD5 checksum of the
10447 file(s) which make(s) up a binary package in the
10448 distribution. If the package is split into several parts
10449 the values for the parts are listed in order, separated by
10454 <sect1 id="pkg-f-Status">
10455 <heading><tt>Status</tt></heading>
10458 This field in <prgn>dpkg</prgn>'s status file records
10459 whether the user wants a package installed, removed or
10460 left alone, whether it is broken (requiring
10461 re-installation) or not and what its current state on the
10462 system is. Each of these pieces of information is a
10467 <sect1 id="pkg-f-Config-Version">
10468 <heading><tt>Config-Version</tt></heading>
10471 If a package is not installed or not configured, this
10472 field in <prgn>dpkg</prgn>'s status file records the last
10473 version of the package which was successfully
10478 <sect1 id="pkg-f-Conffiles">
10479 <heading><tt>Conffiles</tt></heading>
10482 This field in <prgn>dpkg</prgn>'s status file contains
10483 information about the automatically-managed configuration
10484 files held by a package. This field should <em>not</em>
10485 appear anywhere in a package!
10490 <heading>Obsolete fields</heading>
10493 These are still recognized by <prgn>dpkg</prgn> but should
10494 not appear anywhere any more.
10496 <taglist compact="compact">
10498 <tag><tt>Revision</tt></tag>
10499 <tag><tt>Package-Revision</tt></tag>
10500 <tag><tt>Package_Revision</tt></tag>
10502 The Debian revision part of the package version was
10503 at one point in a separate control file field. This
10504 field went through several names.
10507 <tag><tt>Recommended</tt></tag>
10508 <item>Old name for <tt>Recommends</tt>.</item>
10510 <tag><tt>Optional</tt></tag>
10511 <item>Old name for <tt>Suggests</tt>.</item>
10513 <tag><tt>Class</tt></tag>
10514 <item>Old name for <tt>Priority</tt>.</item>
10523 <appendix id="pkg-conffiles">
10524 <heading>Configuration file handling (from old Packaging Manual)</heading>
10527 <prgn>dpkg</prgn> can do a certain amount of automatic
10528 handling of package configuration files.
10532 Whether this mechanism is appropriate depends on a number of
10533 factors, but basically there are two approaches to any
10534 particular configuration file.
10538 The easy method is to ship a best-effort configuration in the
10539 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10540 handle updates. If the user is unlikely to want to edit the
10541 file, but you need them to be able to without losing their
10542 changes, and a new package with a changed version of the file
10543 is only released infrequently, this is a good approach.
10547 The hard method is to build the configuration file from
10548 scratch in the <prgn>postinst</prgn> script, and to take the
10549 responsibility for fixing any mistakes made in earlier
10550 versions of the package automatically. This will be
10551 appropriate if the file is likely to need to be different on
10555 <sect><heading>Automatic handling of configuration files by
10560 A package may contain a control area file called
10561 <tt>conffiles</tt>. This file should be a list of filenames
10562 of configuration files needing automatic handling, separated
10563 by newlines. The filenames should be absolute pathnames,
10564 and the files referred to should actually exist in the
10569 When a package is upgraded <prgn>dpkg</prgn> will process
10570 the configuration files during the configuration stage,
10571 shortly before it runs the package's <prgn>postinst</prgn>
10576 For each file it checks to see whether the version of the
10577 file included in the package is the same as the one that was
10578 included in the last version of the package (the one that is
10579 being upgraded from); it also compares the version currently
10580 installed on the system with the one shipped with the last
10585 If neither the user nor the package maintainer has changed
10586 the file, it is left alone. If one or the other has changed
10587 their version, then the changed version is preferred - i.e.,
10588 if the user edits their file, but the package maintainer
10589 doesn't ship a different version, the user's changes will
10590 stay, silently, but if the maintainer ships a new version
10591 and the user hasn't edited it the new version will be
10592 installed (with an informative message). If both have
10593 changed their version the user is prompted about the problem
10594 and must resolve the differences themselves.
10598 The comparisons are done by calculating the MD5 message
10599 digests of the files, and storing the MD5 of the file as it
10600 was included in the most recent version of the package.
10604 When a package is installed for the first time
10605 <prgn>dpkg</prgn> will install the file that comes with it,
10606 unless that would mean overwriting a file already on the
10611 However, note that <prgn>dpkg</prgn> will <em>not</em>
10612 replace a conffile that was removed by the user (or by a
10613 script). This is necessary because with some programs a
10614 missing file produces an effect hard or impossible to
10615 achieve in another way, so that a missing file needs to be
10616 kept that way if the user did it.
10620 Note that a package should <em>not</em> modify a
10621 <prgn>dpkg</prgn>-handled conffile in its maintainer
10622 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10623 the user confusing and possibly dangerous options for
10624 conffile update when the package is upgraded.</p>
10627 <sect><heading>Fully-featured maintainer script configuration
10632 For files which contain site-specific information such as
10633 the hostname and networking details and so forth, it is
10634 better to create the file in the package's
10635 <prgn>postinst</prgn> script.
10639 This will typically involve examining the state of the rest
10640 of the system to determine values and other information, and
10641 may involve prompting the user for some information which
10642 can't be obtained some other way.
10646 When using this method there are a couple of important
10647 issues which should be considered:
10651 If you discover a bug in the program which generates the
10652 configuration file, or if the format of the file changes
10653 from one version to the next, you will have to arrange for
10654 the postinst script to do something sensible - usually this
10655 will mean editing the installed configuration file to remove
10656 the problem or change the syntax. You will have to do this
10657 very carefully, since the user may have changed the file,
10658 perhaps to fix the very problem that your script is trying
10659 to deal with - you will have to detect these situations and
10660 deal with them correctly.
10664 If you do go down this route it's probably a good idea to
10665 make the program that generates the configuration file(s) a
10666 separate program in <file>/usr/sbin</file>, by convention called
10667 <file><var>package</var>config</file> and then run that if
10668 appropriate from the post-installation script. The
10669 <tt><var>package</var>config</tt> program should not
10670 unquestioningly overwrite an existing configuration - if its
10671 mode of operation is geared towards setting up a package for
10672 the first time (rather than any arbitrary reconfiguration
10673 later) you should have it check whether the configuration
10674 already exists, and require a <tt>--force</tt> flag to
10675 overwrite it.</p></sect>
10678 <appendix id="pkg-alternatives"><heading>Alternative versions of
10679 an interface - <prgn>update-alternatives</prgn> (from old
10684 When several packages all provide different versions of the
10685 same program or file it is useful to have the system select a
10686 default, but to allow the system administrator to change it
10687 and have their decisions respected.
10691 For example, there are several versions of the <prgn>vi</prgn>
10692 editor, and there is no reason to prevent all of them from
10693 being installed at once, each under their own name
10694 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10695 Nevertheless it is desirable to have the name <tt>vi</tt>
10696 refer to something, at least by default.
10700 If all the packages involved cooperate, this can be done with
10701 <prgn>update-alternatives</prgn>.
10705 Each package provides its own version under its own name, and
10706 calls <prgn>update-alternatives</prgn> in its postinst to
10707 register its version (and again in its prerm to deregister
10712 See the man page <manref name="update-alternatives"
10713 section="8"> for details.
10717 If <prgn>update-alternatives</prgn> does not seem appropriate
10718 you may wish to consider using diversions instead.</p>
10721 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10722 package's version of a file (from old Packaging Manual)
10726 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10727 when it reinstalls the package it belongs to, and to have it
10728 put the file from the package somewhere else instead.
10732 This can be used locally to override a package's version of a
10733 file, or by one package to override another's version (or
10734 provide a wrapper for it).
10738 Before deciding to use a diversion, read <ref
10739 id="pkg-alternatives"> to see if you really want a diversion
10740 rather than several alternative versions of a program.
10744 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10745 and updated by a special program <prgn>dpkg-divert</prgn>.
10746 Please see <manref name="dpkg-divert" section="8"> for full
10747 details of its operation.
10751 When a package wishes to divert a file from another, it should
10752 call <prgn>dpkg-divert</prgn> in its preinst to add the
10753 diversion and rename the existing file. For example,
10754 supposing that a <prgn>smailwrapper</prgn> package wishes to
10755 install a wrapper around <file>/usr/sbin/smail</file>:
10757 dpkg-divert --package smailwrapper --add --rename \
10758 --divert /usr/sbin/smail.real /usr/sbin/smail
10759 </example> The <tt>--package smailwrapper</tt> ensures that
10760 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
10761 can bypass the diversion and get installed as the true version.
10762 It's safe to add the diversion unconditionally on upgrades since
10763 it will be left unchanged if it already exists, but
10764 <prgn>dpkg-divert</prgn> will display a message. To suppress that
10765 message, make the command conditional on the version from which
10766 the package is being upgraded:
10768 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
10769 dpkg-divert --package smailwrapper --add --rename \
10770 --divert /usr/sbin/smail.real /usr/sbin/smail
10772 </example> where <tt>1.0-2</tt> is the version at which the
10773 diversion was first added to the package. Running the command
10774 during abort-upgrade is pointless but harmless.
10778 The postrm has to do the reverse:
10780 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
10781 dpkg-divert --package smailwrapper --remove --rename \
10782 --divert /usr/sbin/smail.real /usr/sbin/smail
10784 </example> If the diversion was added at a particular version, the
10785 postrm should also handle the failure case of upgrading from an
10786 older version (unless the older version is so old that direct
10787 upgrades are no longer supported):
10789 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
10790 dpkg-divert --package smailwrapper --remove --rename \
10791 --divert /usr/sbin/smail.real /usr/sbin/smail
10793 </example> where <tt>1.02-2</tt> is the version at which the
10794 diversion was first added to the package. The postrm should not
10795 remove the diversion on upgrades both because there's no reason to
10796 remove the diversion only to immediately re-add it and since the
10797 postrm of the old package is run after unpacking so the removal of
10798 the diversion will fail.
10802 Do not attempt to divert a file which is vitally important for
10803 the system's operation - when using <prgn>dpkg-divert</prgn>
10804 there is a time, after it has been diverted but before
10805 <prgn>dpkg</prgn> has installed the new version, when the file
10806 does not exist.</p>
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