1 <!doctype debiandoc system [
2 <!-- include version information so we don't have to hard code it
3 within the document -->
4 <!entity % versiondata SYSTEM "version.ent"> %versiondata;
10 <title>Debian Policy Manual</title>
11 <author><qref id="authors">The Debian Policy Mailing List</qref></author>
12 <version>version &version;, &date;</version>
15 This manual describes the policy requirements for the Debian
16 GNU/Linux distribution. This includes the structure and
17 contents of the Debian archive and several design issues of
18 the operating system, as well as technical requirements that
19 each package must satisfy to be included in the distribution.
24 Copyright © 1996,1997,1998 Ian Jackson
25 and Christian Schwarz.
28 These are the copyright dates of the original Policy manual.
29 Since then, this manual has been updated by many others. No
30 comprehensive collection of copyright notices for subsequent
35 This manual is free software; you may redistribute it and/or
36 modify it under the terms of the GNU General Public License
37 as published by the Free Software Foundation; either version
38 2, or (at your option) any later version.
42 This is distributed in the hope that it will be useful, but
43 <em>without any warranty</em>; without even the implied
44 warranty of merchantability or fitness for a particular
45 purpose. See the GNU General Public License for more
50 A copy of the GNU General Public License is available as
51 <file>/usr/share/common-licenses/GPL</file> in the Debian GNU/Linux
52 distribution or on the World Wide Web at
53 <url id="http://www.gnu.org/copyleft/gpl.html"
54 name="the GNU General Public Licence">. You can also
55 obtain it by writing to the Free Software Foundation, Inc.,
56 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
64 <heading>About this manual</heading>
66 <heading>Scope</heading>
68 This manual describes the policy requirements for the Debian
69 GNU/Linux distribution. This includes the structure and
70 contents of the Debian archive and several design issues of the
71 operating system, as well as technical requirements that
72 each package must satisfy to be included in the
77 This manual also describes Debian policy as it relates to
78 creating Debian packages. It is not a tutorial on how to build
79 packages, nor is it exhaustive where it comes to describing
80 the behavior of the packaging system. Instead, this manual
81 attempts to define the interface to the package management
82 system that the developers have to be conversant with.<footnote>
83 Informally, the criteria used for inclusion is that the
84 material meet one of the following requirements:
85 <taglist compact="compact">
86 <tag>Standard interfaces</tag>
88 The material presented represents an interface to
89 the packaging system that is mandated for use, and
90 is used by, a significant number of packages, and
91 therefore should not be changed without peer
92 review. Package maintainers can then rely on this
93 interface not changing, and the package management
94 software authors need to ensure compatibility with
95 this interface definition. (Control file and
96 changelog file formats are examples.)
98 <tag>Chosen Convention</tag>
100 If there are a number of technically viable choices
101 that can be made, but one needs to select one of
102 these options for inter-operability. The version
103 number format is one example.
106 Please note that these are not mutually exclusive;
107 selected conventions often become parts of standard
113 The footnotes present in this manual are
114 merely informative, and are not part of Debian policy itself.
118 The appendices to this manual are not necessarily normative,
119 either. Please see <ref id="pkg-scope"> for more information.
123 In the normative part of this manual,
124 the words <em>must</em>, <em>should</em> and
125 <em>may</em>, and the adjectives <em>required</em>,
126 <em>recommended</em> and <em>optional</em>, are used to
127 distinguish the significance of the various guidelines in
128 this policy document. Packages that do not conform to the
129 guidelines denoted by <em>must</em> (or <em>required</em>)
130 will generally not be considered acceptable for the Debian
131 distribution. Non-conformance with guidelines denoted by
132 <em>should</em> (or <em>recommended</em>) will generally be
133 considered a bug, but will not necessarily render a package
134 unsuitable for distribution. Guidelines denoted by
135 <em>may</em> (or <em>optional</em>) are truly optional and
136 adherence is left to the maintainer's discretion.
140 These classifications are roughly equivalent to the bug
141 severities <em>serious</em> (for <em>must</em> or
142 <em>required</em> directive violations), <em>minor</em>,
143 <em>normal</em> or <em>important</em>
144 (for <em>should</em> or <em>recommended</em> directive
145 violations) and <em>wishlist</em> (for <em>optional</em>
148 Compare RFC 2119. Note, however, that these words are
149 used in a different way in this document.
154 Much of the information presented in this manual will be
155 useful even when building a package which is to be
156 distributed in some other way or is intended for local use
162 <heading>New versions of this document</heading>
165 This manual is distributed via the Debian package
166 <package><url name="debian-policy"
167 id="http://packages.debian.org/debian-policy"></package>
168 (<httpsite>packages.debian.org</httpsite>
169 <httppath>/debian-policy</httppath>).
173 The current version of this document is also available from
174 the Debian web mirrors at
175 <tt><url name="/doc/debian-policy/"
176 id="http://www.debian.org/doc/debian-policy/"></tt>.
178 <httpsite>www.debian.org</httpsite>
179 <httppath>/doc/debian-policy/</httppath>)
180 Also available from the same directory are several other
181 formats: <file>policy.html.tar.gz</file>
182 (<httppath>/doc/debian-policy/policy.html.tar.gz</httppath>),
183 <file>policy.pdf.gz</file>
184 (<httppath>/doc/debian-policy/policy.pdf.gz</httppath>)
185 and <file>policy.ps.gz</file>
186 (<httppath>/doc/debian-policy/policy.ps.gz</httppath>).
190 The <package>debian-policy</package> package also includes the file
191 <file>upgrading-checklist.txt.gz</file> which indicates policy
192 changes between versions of this document.
197 <heading>Authors and Maintainers</heading>
200 Originally called "Debian GNU/Linux Policy Manual", this
201 manual was initially written in 1996 by Ian Jackson.
202 It was revised on November 27th, 1996 by David A. Morris.
203 Christian Schwarz added new sections on March 15th, 1997,
204 and reworked/restructured it in April-July 1997.
205 Christoph Lameter contributed the "Web Standard".
206 Julian Gilbey largely restructured it in 2001.
210 Since September 1998, the responsibility for the contents of
211 this document lies on the <url name="debian-policy mailing list"
212 id="mailto:debian-policy@lists.debian.org">. Proposals
213 are discussed there and inserted into policy after a certain
214 consensus is established.
215 <!-- insert shameless policy-process plug here eventually -->
216 The actual editing is done by a group of maintainers that have
217 no editorial powers. These are the current maintainers:
220 <item>Julian Gilbey</item>
221 <item>Branden Robinson</item>
222 <item>Josip Rodin</item>
223 <item>Manoj Srivastava</item>
228 While the authors of this document have tried hard to avoid
229 typos and other errors, these do still occur. If you discover
230 an error in this manual or if you want to give any
231 comments, suggestions, or criticisms please send an email to
232 the Debian Policy List,
233 <email>debian-policy@lists.debian.org</email>, or submit a
234 bug report against the <tt>debian-policy</tt> package.
238 Please do not try to reach the individual authors or maintainers
239 of the Policy Manual regarding changes to the Policy.
244 <heading>Related documents</heading>
247 There are several other documents other than this Policy Manual
248 that are necessary to fully understand some Debian policies and
253 The external "sub-policy" documents are referred to in:
254 <list compact="compact">
255 <item><ref id="fhs"></item>
256 <item><ref id="virtual_pkg"></item>
257 <item><ref id="menus"></item>
258 <item><ref id="mime"></item>
259 <item><ref id="perl"></item>
260 <item><ref id="maintscriptprompt"></item>
261 <item><ref id="emacs"></item>
266 In addition to those, which carry the weight of policy, there
267 is the Debian Developer's Reference. This document describes
268 procedures and resources for Debian developers, but it is
269 <em>not</em> normative; rather, it includes things that don't
270 belong in the Policy, such as best practices for developers.
274 The Developer's Reference is available in the
275 <package>developers-reference</package> package.
276 It's also available from the Debian web mirrors at
277 <tt><url name="/doc/developers-reference/"
278 id="http://www.debian.org/doc/developers-reference/"></tt>.
282 <sect id="definitions">
283 <heading>Definitions</heading>
286 The following terms are used in this Policy Manual:
290 The character encoding specified by ANSI X3.4-1986 and its
291 predecessor standards, referred to in MIME as US-ASCII, and
292 corresponding to an encoding in eight bits per character of
293 the first 128 <url id="http://www.unicode.org/"
294 name="Unicode"> characters, with the eighth bit always zero.
298 The transformation format (sometimes called encoding) of
299 <url id="http://www.unicode.org/" name="Unicode"> defined by
300 <url id="http://www.rfc-editor.org/rfc/rfc3629.txt"
301 name="RFC 3629">. UTF-8 has the useful property of having
302 ASCII as a subset, so any text encoded in ASCII is trivially
312 <heading>The Debian Archive</heading>
315 The Debian GNU/Linux system is maintained and distributed as a
316 collection of <em>packages</em>. Since there are so many of
317 them (currently well over 15000), they are split into
318 <em>sections</em> and given <em>priorities</em> to simplify
319 the handling of them.
323 The effort of the Debian project is to build a free operating
324 system, but not every package we want to make accessible is
325 <em>free</em> in our sense (see the Debian Free Software
326 Guidelines, below), or may be imported/exported without
327 restrictions. Thus, the archive is split into areas<footnote>
328 The Debian archive software uses the term "component" internally
329 and in the Release file format to refer to the division of an
330 archive. The Debian Social Contract simply refers to "areas."
331 This document uses terminology similar to the Social Contract.
332 </footnote> based on their licenses and other restrictions.
336 The aims of this are:
338 <list compact="compact">
339 <item>to allow us to make as much software available as we can</item>
340 <item>to allow us to encourage everyone to write free software,
342 <item>to allow us to make it easy for people to produce
343 CD-ROMs of our system without violating any licenses,
344 import/export restrictions, or any other laws.</item>
349 The <em>main</em> archive area forms the <em>Debian GNU/Linux
354 Packages in the other archive areas (<tt>contrib</tt>,
355 <tt>non-free</tt>) are not considered to be part of the Debian
356 distribution, although we support their use and provide
357 infrastructure for them (such as our bug-tracking system and
358 mailing lists). This Debian Policy Manual applies to these
363 <heading>The Debian Free Software Guidelines</heading>
365 The Debian Free Software Guidelines (DFSG) form our
366 definition of "free software". These are:
368 <tag>1. Free Redistribution
371 The license of a Debian component may not restrict any
372 party from selling or giving away the software as a
373 component of an aggregate software distribution
374 containing programs from several different
375 sources. The license may not require a royalty or
376 other fee for such sale.
381 The program must include source code, and must allow
382 distribution in source code as well as compiled form.
384 <tag>3. Derived Works
387 The license must allow modifications and derived
388 works, and must allow them to be distributed under the
389 same terms as the license of the original software.
391 <tag>4. Integrity of The Author's Source Code
394 The license may restrict source-code from being
395 distributed in modified form <em>only</em> if the
396 license allows the distribution of "patch files"
397 with the source code for the purpose of modifying the
398 program at build time. The license must explicitly
399 permit distribution of software built from modified
400 source code. The license may require derived works to
401 carry a different name or version number from the
402 original software. (This is a compromise. The Debian
403 Project encourages all authors to not restrict any
404 files, source or binary, from being modified.)
406 <tag>5. No Discrimination Against Persons or Groups
409 The license must not discriminate against any person
412 <tag>6. No Discrimination Against Fields of Endeavor
415 The license must not restrict anyone from making use
416 of the program in a specific field of endeavor. For
417 example, it may not restrict the program from being
418 used in a business, or from being used for genetic
421 <tag>7. Distribution of License
424 The rights attached to the program must apply to all
425 to whom the program is redistributed without the need
426 for execution of an additional license by those
429 <tag>8. License Must Not Be Specific to Debian
432 The rights attached to the program must not depend on
433 the program's being part of a Debian system. If the
434 program is extracted from Debian and used or
435 distributed without Debian but otherwise within the
436 terms of the program's license, all parties to whom
437 the program is redistributed must have the same
438 rights as those that are granted in conjunction with
441 <tag>9. License Must Not Contaminate Other Software
444 The license must not place restrictions on other
445 software that is distributed along with the licensed
446 software. For example, the license must not insist
447 that all other programs distributed on the same medium
448 must be free software.
450 <tag>10. Example Licenses
453 The "GPL," "BSD," and "Artistic" licenses are examples of
454 licenses that we consider <em>free</em>.
461 <heading>Archive areas</heading>
464 <heading>The main archive area</heading>
467 Every package in <em>main</em> must comply with the DFSG
468 (Debian Free Software Guidelines).
472 In addition, the packages in <em>main</em>
473 <list compact="compact">
475 must not require a package outside of <em>main</em>
476 for compilation or execution (thus, the package must
477 not declare a "Depends", "Recommends", or
478 "Build-Depends" relationship on a non-<em>main</em>
482 must not be so buggy that we refuse to support them,
486 must meet all policy requirements presented in this
495 <heading>The contrib archive area</heading>
498 Every package in <em>contrib</em> must comply with the DFSG.
502 In addition, the packages in <em>contrib</em>
503 <list compact="compact">
505 must not be so buggy that we refuse to support them,
509 must meet all policy requirements presented in this
517 Examples of packages which would be included in
518 <em>contrib</em> are:
519 <list compact="compact">
521 free packages which require <em>contrib</em>,
522 <em>non-free</em> packages or packages which are not
523 in our archive at all for compilation or execution,
527 wrapper packages or other sorts of free accessories for
534 <sect1 id="non-free">
535 <heading>The non-free archive area</heading>
538 Packages must be placed in <em>non-free</em> if they are
539 not compliant with the DFSG or are encumbered by patents
540 or other legal issues that make their distribution
545 In addition, the packages in <em>non-free</em>
546 <list compact="compact">
548 must not be so buggy that we refuse to support them,
552 must meet all policy requirements presented in this
553 manual that it is possible for them to meet.
555 It is possible that there are policy
556 requirements which the package is unable to
557 meet, for example, if the source is
558 unavailable. These situations will need to be
559 handled on a case-by-case basis.
568 <sect id="pkgcopyright">
569 <heading>Copyright considerations</heading>
572 Every package must be accompanied by a verbatim copy of its
573 copyright information and distribution license in the file
574 <file>/usr/share/doc/<var>package</var>/copyright</file>
575 (see <ref id="copyrightfile"> for further details).
579 We reserve the right to restrict files from being included
580 anywhere in our archives if
581 <list compact="compact">
583 their use or distribution would break a law,
586 there is an ethical conflict in their distribution or
590 we would have to sign a license for them, or
593 their distribution would conflict with other project
600 Programs whose authors encourage the user to make
601 donations are fine for the main distribution, provided
602 that the authors do not claim that not donating is
603 immoral, unethical, illegal or something similar; in such
604 a case they must go in <em>non-free</em>.
608 Packages whose copyright permission notices (or patent
609 problems) do not even allow redistribution of binaries
610 only, and where no special permission has been obtained,
611 must not be placed on the Debian FTP site and its mirrors
616 Note that under international copyright law (this applies
617 in the United States, too), <em>no</em> distribution or
618 modification of a work is allowed without an explicit
619 notice saying so. Therefore a program without a copyright
620 notice <em>is</em> copyrighted and you may not do anything
621 to it without risking being sued! Likewise if a program
622 has a copyright notice but no statement saying what is
623 permitted then nothing is permitted.
627 Many authors are unaware of the problems that restrictive
628 copyrights (or lack of copyright notices) can cause for
629 the users of their supposedly-free software. It is often
630 worthwhile contacting such authors diplomatically to ask
631 them to modify their license terms. However, this can be a
632 politically difficult thing to do and you should ask for
633 advice on the <tt>debian-legal</tt> mailing list first, as
638 When in doubt about a copyright, send mail to
639 <email>debian-legal@lists.debian.org</email>. Be prepared
640 to provide us with the copyright statement. Software
641 covered by the GPL, public domain software and BSD-like
642 copyrights are safe; be wary of the phrases "commercial
643 use prohibited" and "distribution restricted".
647 <sect id="subsections">
648 <heading>Sections</heading>
651 The packages in the archive areas <em>main</em>,
652 <em>contrib</em> and <em>non-free</em> are grouped further into
653 <em>sections</em> to simplify handling.
657 The archive area and section for each package should be
658 specified in the package's <tt>Section</tt> control record (see
659 <ref id="f-Section">). However, the maintainer of the Debian
660 archive may override this selection to ensure the consistency of
661 the Debian distribution. The <tt>Section</tt> field should be
663 <list compact="compact">
665 <em>section</em> if the package is in the
666 <em>main</em> archive area,
669 <em>area/section</em> if the package is in
670 the <em>contrib</em> or <em>non-free</em>
677 The Debian archive maintainers provide the authoritative
678 list of sections. At present, they are:
679 <em>admin</em>, <em>cli-mono</em>, <em>comm</em>, <em>database</em>,
680 <em>devel</em>, <em>debug</em>, <em>doc</em>, <em>editors</em>,
681 <em>electronics</em>, <em>embedded</em>, <em>fonts</em>,
682 <em>games</em>, <em>gnome</em>, <em>graphics</em>, <em>gnu-r</em>,
683 <em>gnustep</em>, <em>hamradio</em>, <em>haskell</em>,
684 <em>httpd</em>, <em>interpreters</em>, <em>java</em>, <em>kde</em>,
685 <em>kernel</em>, <em>libs</em>, <em>libdevel</em>, <em>lisp</em>,
686 <em>localization</em>, <em>mail</em>, <em>math</em>, <em>misc</em>,
687 <em>net</em>, <em>news</em>, <em>ocaml</em>, <em>oldlibs</em>,
688 <em>otherosfs</em>, <em>perl</em>, <em>php</em>, <em>python</em>,
689 <em>ruby</em>, <em>science</em>, <em>shells</em>, <em>sound</em>,
690 <em>tex</em>, <em>text</em>, <em>utils</em>, <em>vcs</em>,
691 <em>video</em>, <em>web</em>, <em>x11</em>, <em>xfce</em>,
692 <em>zope</em>. The additional section <em>debian-installer</em>
693 contains special packages used by the installer and is not used
694 for normal Debian packages.
698 For more information about the sections and their definitions,
699 see the <url id="http://packages.debian.org/unstable/"
700 name="list of sections in unstable">.
704 <sect id="priorities">
705 <heading>Priorities</heading>
708 Each package should have a <em>priority</em> value, which is
709 included in the package's <em>control record</em>
710 (see <ref id="f-Priority">).
711 This information is used by the Debian package management tools to
712 separate high-priority packages from less-important packages.
716 The following <em>priority levels</em> are recognized by the
717 Debian package management tools.
719 <tag><tt>required</tt></tag>
721 Packages which are necessary for the proper
722 functioning of the system (usually, this means that
723 dpkg functionality depends on these packages).
724 Removing a <tt>required</tt> package may cause your
725 system to become totally broken and you may not even
726 be able to use <prgn>dpkg</prgn> to put things back,
727 so only do so if you know what you are doing. Systems
728 with only the <tt>required</tt> packages are probably
729 unusable, but they do have enough functionality to
730 allow the sysadmin to boot and install more software.
732 <tag><tt>important</tt></tag>
734 Important programs, including those which one would
735 expect to find on any Unix-like system. If the
736 expectation is that an experienced Unix person who
737 found it missing would say "What on earth is going on,
738 where is <prgn>foo</prgn>?", it must be an
739 <tt>important</tt> package.<footnote>
740 This is an important criterion because we are
741 trying to produce, amongst other things, a free
744 Other packages without which the system will not run
745 well or be usable must also have priority
746 <tt>important</tt>. This does
747 <em>not</em> include Emacs, the X Window System, TeX
748 or any other large applications. The
749 <tt>important</tt> packages are just a bare minimum of
750 commonly-expected and necessary tools.
752 <tag><tt>standard</tt></tag>
754 These packages provide a reasonably small but not too
755 limited character-mode system. This is what will be
756 installed by default if the user doesn't select anything
757 else. It doesn't include many large applications.
759 <tag><tt>optional</tt></tag>
761 (In a sense everything that isn't required is
762 optional, but that's not what is meant here.) This is
763 all the software that you might reasonably want to
764 install if you didn't know what it was and don't have
765 specialized requirements. This is a much larger system
766 and includes the X Window System, a full TeX
767 distribution, and many applications. Note that
768 optional packages should not conflict with each other.
770 <tag><tt>extra</tt></tag>
772 This contains all packages that conflict with others
773 with required, important, standard or optional
774 priorities, or are only likely to be useful if you
775 already know what they are or have specialized
776 requirements (such as packages containing only detached
783 Packages must not depend on packages with lower priority
784 values (excluding build-time dependencies). In order to
785 ensure this, the priorities of one or more packages may need
794 <heading>Binary packages</heading>
797 The Debian GNU/Linux distribution is based on the Debian
798 package management system, called <prgn>dpkg</prgn>. Thus,
799 all packages in the Debian distribution must be provided
800 in the <tt>.deb</tt> file format.
804 <heading>The package name</heading>
807 Every package must have a name that's unique within the Debian
812 The package name is included in the control field
813 <tt>Package</tt>, the format of which is described
814 in <ref id="f-Package">.
815 The package name is also included as a part of the file name
816 of the <tt>.deb</tt> file.
821 <heading>The version of a package</heading>
824 Every package has a version number recorded in its
825 <tt>Version</tt> control file field, described in
826 <ref id="f-Version">.
830 The package management system imposes an ordering on version
831 numbers, so that it can tell whether packages are being up- or
832 downgraded and so that package system front end applications
833 can tell whether a package it finds available is newer than
834 the one installed on the system. The version number format
835 has the most significant parts (as far as comparison is
836 concerned) at the beginning.
840 If an upstream package has problematic version numbers they
841 should be converted to a sane form for use in the
842 <tt>Version</tt> field.
846 <heading>Version numbers based on dates</heading>
849 In general, Debian packages should use the same version
850 numbers as the upstream sources.
854 However, in some cases where the upstream version number is
855 based on a date (e.g., a development "snapshot" release) the
856 package management system cannot handle these version
857 numbers without epochs. For example, dpkg will consider
858 "96May01" to be greater than "96Dec24".
862 To prevent having to use epochs for every new upstream
863 version, the date based portion of the version number
864 should be changed to the following format in such cases:
865 "19960501", "19961224". It is up to the maintainer whether
866 they want to bother the upstream maintainer to change
867 the version numbers upstream, too.
871 Note that other version formats based on dates which are
872 parsed correctly by the package management system should
873 <em>not</em> be changed.
877 Native Debian packages (i.e., packages which have been
878 written especially for Debian) whose version numbers include
879 dates should always use the "YYYYMMDD" format.
886 <heading>The maintainer of a package</heading>
889 Every package must have a Debian maintainer (the
890 maintainer may be one person or a group of people
891 reachable from a common email address, such as a mailing
892 list). The maintainer is responsible for ensuring that
893 the package is placed in the appropriate distributions.
897 The maintainer must be specified in the
898 <tt>Maintainer</tt> control field with their correct name
899 and a working email address. If one person maintains
900 several packages, they should try to avoid having
901 different forms of their name and email address in
902 the <tt>Maintainer</tt> fields of those packages.
906 The format of the <tt>Maintainer</tt> control field is
907 described in <ref id="f-Maintainer">.
911 If the maintainer of a package quits from the Debian
912 project, "Debian QA Group"
913 <email>packages@qa.debian.org</email> takes over the
914 maintainer-ship of the package until someone else
915 volunteers for that task. These packages are called
916 <em>orphaned packages</em>.<footnote>
917 The detailed procedure for doing this gracefully can
918 be found in the Debian Developer's Reference,
919 see <ref id="related">.
924 <sect id="descriptions">
925 <heading>The description of a package</heading>
928 Every Debian package must have an extended description
929 stored in the appropriate field of the control record.
930 The technical information about the format of the
931 <tt>Description</tt> field is in <ref id="f-Description">.
935 The description should describe the package (the program) to a
936 user (system administrator) who has never met it before so that
937 they have enough information to decide whether they want to
938 install it. This description should not just be copied verbatim
939 from the program's documentation.
943 Put important information first, both in the synopsis and
944 extended description. Sometimes only the first part of the
945 synopsis or of the description will be displayed. You can
946 assume that there will usually be a way to see the whole
947 extended description.
951 The description should also give information about the
952 significant dependencies and conflicts between this package
953 and others, so that the user knows why these dependencies and
954 conflicts have been declared.
958 Instructions for configuring or using the package should
959 not be included (that is what installation scripts,
960 manual pages, info files, etc., are for). Copyright
961 statements and other administrivia should not be included
962 either (that is what the copyright file is for).
965 <sect1 id="synopsis"><heading>The single line synopsis</heading>
968 The single line synopsis should be kept brief - certainly
973 Do not include the package name in the synopsis line. The
974 display software knows how to display this already, and you
975 do not need to state it. Remember that in many situations
976 the user may only see the synopsis line - make it as
977 informative as you can.
982 <sect1 id="extendeddesc"><heading>The extended description</heading>
985 Do not try to continue the single line synopsis into the
986 extended description. This will not work correctly when
987 the full description is displayed, and makes no sense
988 where only the summary (the single line synopsis) is
993 The extended description should describe what the package
994 does and how it relates to the rest of the system (in terms
995 of, for example, which subsystem it is which part of).
999 The description field needs to make sense to anyone, even
1000 people who have no idea about any of the things the
1001 package deals with.<footnote>
1002 The blurb that comes with a program in its
1003 announcements and/or <prgn>README</prgn> files is
1004 rarely suitable for use in a description. It is
1005 usually aimed at people who are already in the
1006 community where the package is used.
1015 <heading>Dependencies</heading>
1018 Every package must specify the dependency information
1019 about other packages that are required for the first to
1024 For example, a dependency entry must be provided for any
1025 shared libraries required by a dynamically-linked executable
1026 binary in a package.
1030 Packages are not required to declare any dependencies they
1031 have on other packages which are marked <tt>Essential</tt>
1032 (see below), and should not do so unless they depend on a
1033 particular version of that package.<footnote>
1035 Essential is needed in part to avoid unresolvable dependency
1036 loops on upgrade. If packages add unnecessary dependencies
1037 on packages in this set, the chances that there
1038 <strong>will</strong> be an unresolvable dependency loop
1039 caused by forcing these Essential packages to be configured
1040 first before they need to be is greatly increased. It also
1041 increases the chances that frontends will be unable to
1042 <strong>calculate</strong> an upgrade path, even if one
1046 Also, functionality is rarely ever removed from the
1047 Essential set, but <em>packages</em> have been removed from
1048 the Essential set when the functionality moved to a
1049 different package. So depending on these packages <em>just
1050 in case</em> they stop being essential does way more harm
1057 Sometimes, a package requires another package to be installed
1058 <em>and</em> configured before it can be installed. In this
1059 case, you must specify a <tt>Pre-Depends</tt> entry for
1064 You should not specify a <tt>Pre-Depends</tt> entry for a
1065 package before this has been discussed on the
1066 <tt>debian-devel</tt> mailing list and a consensus about
1067 doing that has been reached.
1071 The format of the package interrelationship control fields is
1072 described in <ref id="relationships">.
1076 <sect id="virtual_pkg">
1077 <heading>Virtual packages</heading>
1080 Sometimes, there are several packages which offer
1081 more-or-less the same functionality. In this case, it's
1082 useful to define a <em>virtual package</em> whose name
1083 describes that common functionality. (The virtual
1084 packages only exist logically, not physically; that's why
1085 they are called <em>virtual</em>.) The packages with this
1086 particular function will then <em>provide</em> the virtual
1087 package. Thus, any other package requiring that function
1088 can simply depend on the virtual package without having to
1089 specify all possible packages individually.
1093 All packages should use virtual package names where
1094 appropriate, and arrange to create new ones if necessary.
1095 They should not use virtual package names (except privately,
1096 amongst a cooperating group of packages) unless they have
1097 been agreed upon and appear in the list of virtual package
1098 names. (See also <ref id="virtual">)
1102 The latest version of the authoritative list of virtual
1103 package names can be found in the <tt>debian-policy</tt> package.
1104 It is also available from the Debian web mirrors at
1105 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1106 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>.
1110 The procedure for updating the list is described in the preface
1117 <heading>Base system</heading>
1120 The <tt>base system</tt> is a minimum subset of the Debian
1121 GNU/Linux system that is installed before everything else
1122 on a new system. Only very few packages are allowed to form
1123 part of the base system, in order to keep the required disk
1128 The base system consists of all those packages with priority
1129 <tt>required</tt> or <tt>important</tt>. Many of them will
1130 be tagged <tt>essential</tt> (see below).
1135 <heading>Essential packages</heading>
1138 Essential is defined as the minimal set of functionality that
1139 must be available and usable on the system at all times, even
1140 when packages are in an unconfigured (but unpacked) state.
1141 Packages are tagged <tt>essential</tt> for a system using the
1142 <tt>Essential</tt> control file field. The format of the
1143 <tt>Essential</tt> control field is described in <ref
1148 Since these packages cannot be easily removed (one has to
1149 specify an extra <em>force option</em> to
1150 <prgn>dpkg</prgn> to do so), this flag must not be used
1151 unless absolutely necessary. A shared library package
1152 must not be tagged <tt>essential</tt>; dependencies will
1153 prevent its premature removal, and we need to be able to
1154 remove it when it has been superseded.
1158 Since dpkg will not prevent upgrading of other packages
1159 while an <tt>essential</tt> package is in an unconfigured
1160 state, all <tt>essential</tt> packages must supply all of
1161 their core functionality even when unconfigured. If the
1162 package cannot satisfy this requirement it must not be
1163 tagged as essential, and any packages depending on this
1164 package must instead have explicit dependency fields as
1169 Maintainers should take great care in adding any programs,
1170 interfaces, or functionality to <tt>essential</tt> packages.
1171 Packages may assume that functionality provided by
1172 <tt>essential</tt> packages is always available without
1173 declaring explicit dependencies, which means that removing
1174 functionality from the Essential set is very difficult and is
1175 almost never done. Any capability added to an
1176 <tt>essential</tt> package therefore creates an obligation to
1177 support that capability as part of the Essential set in
1182 You must not tag any packages <tt>essential</tt> before
1183 this has been discussed on the <tt>debian-devel</tt>
1184 mailing list and a consensus about doing that has been
1189 <sect id="maintscripts">
1190 <heading>Maintainer Scripts</heading>
1193 The package installation scripts should avoid producing
1194 output which is unnecessary for the user to see and
1195 should rely on <prgn>dpkg</prgn> to stave off boredom on
1196 the part of a user installing many packages. This means,
1197 amongst other things, using the <tt>--quiet</tt> option on
1198 <prgn>install-info</prgn>.
1202 Errors which occur during the execution of an installation
1203 script must be checked and the installation must not
1204 continue after an error.
1208 Note that in general <ref id="scripts"> applies to package
1209 maintainer scripts, too.
1213 You should not use <prgn>dpkg-divert</prgn> on a file
1214 belonging to another package without consulting the
1215 maintainer of that package first.
1219 All packages which supply an instance of a common command
1220 name (or, in general, filename) should generally use
1221 <prgn>update-alternatives</prgn>, so that they may be
1222 installed together. If <prgn>update-alternatives</prgn>
1223 is not used, then each package must use
1224 <tt>Conflicts</tt> to ensure that other packages are
1225 de-installed. (In this case, it may be appropriate to
1226 specify a conflict against earlier versions of something
1227 that previously did not use
1228 <prgn>update-alternatives</prgn>; this is an exception to
1229 the usual rule that versioned conflicts should be
1233 <sect1 id="maintscriptprompt">
1234 <heading>Prompting in maintainer scripts</heading>
1236 Package maintainer scripts may prompt the user if
1237 necessary. Prompting must be done by communicating
1238 through a program, such as <prgn>debconf</prgn>, which
1239 conforms to the Debian Configuration Management
1240 Specification, version 2 or higher.
1244 Packages which are essential, or which are dependencies of
1245 essential packages, may fall back on another prompting method
1246 if no such interface is available when they are executed.
1250 The Debian Configuration Management Specification is included
1251 in the <file>debconf_specification</file> files in the
1252 <package>debian-policy</package> package.
1253 It is also available from the Debian web mirrors at
1254 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1255 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>.
1259 Packages which use the Debian Configuration Management
1260 Specification may contain an additional
1261 <prgn>config</prgn> script and a <tt>templates</tt>
1262 file in their control archive<footnote>
1263 The control.tar.gz inside the .deb.
1264 See <manref name="deb" section="5">.
1266 The <prgn>config</prgn> script might be run before the
1267 <prgn>preinst</prgn> script, and before the package is unpacked
1268 or any of its dependencies or pre-dependencies are satisfied.
1269 Therefore it must work using only the tools present in
1270 <em>essential</em> packages.<footnote>
1271 <package>Debconf</package> or another tool that
1272 implements the Debian Configuration Management
1273 Specification will also be installed, and any
1274 versioned dependencies on it will be satisfied
1275 before preconfiguration begins.
1280 Packages which use the Debian Configuration Management
1281 Specification must allow for translation of their user-visible
1282 messages by using a gettext-based system such as the one
1283 provided by the <package>po-debconf</package> package.
1287 Packages should try to minimize the amount of prompting
1288 they need to do, and they should ensure that the user
1289 will only ever be asked each question once. This means
1290 that packages should try to use appropriate shared
1291 configuration files (such as <file>/etc/papersize</file> and
1292 <file>/etc/news/server</file>), and shared
1293 <package>debconf</package> variables rather than each
1294 prompting for their own list of required pieces of
1299 It also means that an upgrade should not ask the same
1300 questions again, unless the user has used
1301 <tt>dpkg --purge</tt> to remove the package's configuration.
1302 The answers to configuration questions should be stored in an
1303 appropriate place in <file>/etc</file> so that the user can
1304 modify them, and how this has been done should be
1309 If a package has a vitally important piece of
1310 information to pass to the user (such as "don't run me
1311 as I am, you must edit the following configuration files
1312 first or you risk your system emitting badly-formatted
1313 messages"), it should display this in the
1314 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1315 prompt the user to hit return to acknowledge the
1316 message. Copyright messages do not count as vitally
1317 important (they belong in
1318 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1319 neither do instructions on how to use a program (these
1320 should be in on-line documentation, where all the users
1325 Any necessary prompting should almost always be confined
1326 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1327 script. If it is done in the <prgn>postinst</prgn>, it
1328 should be protected with a conditional so that
1329 unnecessary prompting doesn't happen if a package's
1330 installation fails and the <prgn>postinst</prgn> is
1331 called with <tt>abort-upgrade</tt>,
1332 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1342 <heading>Source packages</heading>
1344 <sect id="standardsversion">
1345 <heading>Standards conformance</heading>
1348 Source packages should specify the most recent version number
1349 of this policy document with which your package complied
1350 when it was last updated.
1354 This information may be used to file bug reports
1355 automatically if your package becomes too much out of date.
1359 The version is specified in the <tt>Standards-Version</tt>
1361 The format of the <tt>Standards-Version</tt> field is
1362 described in <ref id="f-Standards-Version">.
1366 You should regularly, and especially if your package has
1367 become out of date, check for the newest Policy Manual
1368 available and update your package, if necessary. When your
1369 package complies with the new standards you should update the
1370 <tt>Standards-Version</tt> source package field and
1371 release it.<footnote>
1372 See the file <file>upgrading-checklist</file> for
1373 information about policy which has changed between
1374 different versions of this document.
1380 <sect id="pkg-relations">
1381 <heading>Package relationships</heading>
1384 Source packages should specify which binary packages they
1385 require to be installed or not to be installed in order to
1386 build correctly. For example, if building a package
1387 requires a certain compiler, then the compiler should be
1388 specified as a build-time dependency.
1392 It is not necessary to explicitly specify build-time
1393 relationships on a minimal set of packages that are always
1394 needed to compile, link and put in a Debian package a
1395 standard "Hello World!" program written in C or C++. The
1396 required packages are called <em>build-essential</em>, and
1397 an informational list can be found in
1398 <file>/usr/share/doc/build-essential/list</file> (which is
1399 contained in the <tt>build-essential</tt>
1402 <list compact="compact">
1404 This allows maintaining the list separately
1405 from the policy documents (the list does not
1406 need the kind of control that the policy
1410 Having a separate package allows one to install
1411 the build-essential packages on a machine, as
1412 well as allowing other packages such as tasks to
1413 require installation of the build-essential
1414 packages using the depends relation.
1417 The separate package allows bug reports against
1418 the list to be categorized separately from
1419 the policy management process in the BTS.
1426 When specifying the set of build-time dependencies, one
1427 should list only those packages explicitly required by the
1428 build. It is not necessary to list packages which are
1429 required merely because some other package in the list of
1430 build-time dependencies depends on them.<footnote>
1431 The reason for this is that dependencies change, and
1432 you should list all those packages, and <em>only</em>
1433 those packages that <em>you</em> need directly. What
1434 others need is their business. For example, if you
1435 only link against <file>libimlib</file>, you will need to
1436 build-depend on <package>libimlib2-dev</package> but
1437 not against any <tt>libjpeg*</tt> packages, even
1438 though <tt>libimlib2-dev</tt> currently depends on
1439 them: installation of <package>libimlib2-dev</package>
1440 will automatically ensure that all of its run-time
1441 dependencies are satisfied.
1446 If build-time dependencies are specified, it must be
1447 possible to build the package and produce working binaries
1448 on a system with only essential and build-essential
1449 packages installed and also those required to satisfy the
1450 build-time relationships (including any implied
1451 relationships). In particular, this means that version
1452 clauses should be used rigorously in build-time
1453 relationships so that one cannot produce bad or
1454 inconsistently configured packages when the relationships
1455 are properly satisfied.
1459 <ref id="relationships"> explains the technical details.
1464 <heading>Changes to the upstream sources</heading>
1467 If changes to the source code are made that are not
1468 specific to the needs of the Debian system, they should be
1469 sent to the upstream authors in whatever form they prefer
1470 so as to be included in the upstream version of the
1475 If you need to configure the package differently for
1476 Debian or for Linux, and the upstream source doesn't
1477 provide a way to do so, you should add such configuration
1478 facilities (for example, a new <prgn>autoconf</prgn> test
1479 or <tt>#define</tt>) and send the patch to the upstream
1480 authors, with the default set to the way they originally
1481 had it. You can then easily override the default in your
1482 <file>debian/rules</file> or wherever is appropriate.
1486 You should make sure that the <prgn>configure</prgn> utility
1487 detects the correct architecture specification string
1488 (refer to <ref id="arch-spec"> for details).
1492 If you need to edit a <prgn>Makefile</prgn> where GNU-style
1493 <prgn>configure</prgn> scripts are used, you should edit the
1494 <file>.in</file> files rather than editing the
1495 <prgn>Makefile</prgn> directly. This allows the user to
1496 reconfigure the package if necessary. You should
1497 <em>not</em> configure the package and edit the generated
1498 <prgn>Makefile</prgn>! This makes it impossible for someone
1499 else to later reconfigure the package without losing the
1505 <sect id="dpkgchangelog">
1506 <heading>Debian changelog: <file>debian/changelog</file></heading>
1509 Changes in the Debian version of the package should be
1510 briefly explained in the Debian changelog file
1511 <file>debian/changelog</file>.<footnote>
1513 Mistakes in changelogs are usually best rectified by
1514 making a new changelog entry rather than "rewriting
1515 history" by editing old changelog entries.
1518 This includes modifications
1519 made in the Debian package compared to the upstream one
1520 as well as other changes and updates to the package.
1522 Although there is nothing stopping an author who is also
1523 the Debian maintainer from using this changelog for all
1524 their changes, it will have to be renamed if the Debian
1525 and upstream maintainers become different people. In such
1526 a case, however, it might be better to maintain the package
1527 as a non-native package.
1532 The format of the <file>debian/changelog</file> allows the
1533 package building tools to discover which version of the package
1534 is being built and find out other release-specific information.
1538 That format is a series of entries like this:
1540 <example compact="compact">
1541 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1543 [optional blank line(s), stripped]
1545 * <var>change details</var>
1546 <var>more change details</var>
1548 [blank line(s), included in output of dpkg-parsechangelog]
1550 * <var>even more change details</var>
1552 [optional blank line(s), stripped]
1554 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1559 <var>package</var> and <var>version</var> are the source
1560 package name and version number.
1564 <var>distribution(s)</var> lists the distributions where
1565 this version should be installed when it is uploaded - it
1566 is copied to the <tt>Distribution</tt> field in the
1567 <file>.changes</file> file. See <ref id="f-Distribution">.
1571 <var>urgency</var> is the value for the <tt>Urgency</tt>
1572 field in the <file>.changes</file> file for the upload
1573 (see <ref id="f-Urgency">). It is not possible to specify
1574 an urgency containing commas; commas are used to separate
1575 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1576 <prgn>dpkg</prgn> changelog format (though there is
1577 currently only one useful <var>keyword</var>,
1582 The change details may in fact be any series of lines
1583 starting with at least two spaces, but conventionally each
1584 change starts with an asterisk and a separating space and
1585 continuation lines are indented so as to bring them in
1586 line with the start of the text above. Blank lines may be
1587 used here to separate groups of changes, if desired.
1591 If this upload resolves bugs recorded in the Bug Tracking
1592 System (BTS), they may be automatically closed on the
1593 inclusion of this package into the Debian archive by
1594 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1595 in the change details.<footnote>
1596 To be precise, the string should match the following
1597 Perl regular expression:
1599 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1601 Then all of the bug numbers listed will be closed by the
1602 archive maintenance script (<prgn>katie</prgn>) using the
1603 <var>version</var> of the changelog entry.
1605 This information is conveyed via the <tt>Closes</tt> field
1606 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1610 The maintainer name and email address used in the changelog
1611 should be the details of the person uploading <em>this</em>
1612 version. They are <em>not</em> necessarily those of the
1613 usual package maintainer. The information here will be
1614 copied to the <tt>Changed-By</tt> field in the
1615 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1616 and then later used to send an acknowledgement when the
1617 upload has been installed.
1621 The <var>date</var> has the following format<footnote>
1622 This is the same as the format generated by <tt>date
1624 </footnote> (compatible and with the same semantics of
1625 RFC 2822 and RFC 5322):
1626 <example>day-of-week, dd month yyyy hh:mm:ss +zzzz</example>
1628 <list compact="compact">
1630 day-of week is one of: Mon, Tue, Wed, Thu, Fri, Sat, Sun
1633 dd is a one- or two-digit day of the month (01-31)
1636 month is one of: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug,
1639 <item>yyyy is the four-digit year (e.g. 2010)</item>
1640 <item>hh is the two-digit hour (00-23)</item>
1641 <item>mm is the two-digit minutes (00-59)</item>
1642 <item>ss is the two-digit seconds (00-60)</item>
1644 +zzzz or -zzzz is the the time zone offset from Coordinated
1645 Universal Time (UTC). "+" indicates that the time is ahead
1646 of (i.e., east of) UTC and "-" indicates that the time is
1647 behind (i.e., west of) UTC. The first two digits indicate
1648 the hour difference from UTC and the last two digits
1649 indicate the number of additional minutes difference from
1650 UTC. The last two digits must be in the range 00-59.
1656 The first "title" line with the package name must start
1657 at the left hand margin. The "trailer" line with the
1658 maintainer and date details must be preceded by exactly
1659 one space. The maintainer details and the date must be
1660 separated by exactly two spaces.
1664 The entire changelog must be encoded in UTF-8.
1668 For more information on placement of the changelog files
1669 within binary packages, please see <ref id="changelogs">.
1673 <sect id="dpkgcopyright">
1674 <heading>Copyright: <file>debian/copyright</file></heading>
1676 Every package must be accompanied by a verbatim copy of its
1677 copyright information and distribution license in the file
1678 <file>/usr/share/doc/<var>package</var>/copyright</file>
1679 (see <ref id="copyrightfile"> for further details). Also see
1680 <ref id="pkgcopyright"> for further considerations related
1681 to copyrights for packages.
1685 <heading>Error trapping in makefiles</heading>
1688 When <prgn>make</prgn> invokes a command in a makefile
1689 (including your package's upstream makefiles and
1690 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1691 means that <prgn>sh</prgn>'s usual bad error handling
1692 properties apply: if you include a miniature script as one
1693 of the commands in your makefile you'll find that if you
1694 don't do anything about it then errors are not detected
1695 and <prgn>make</prgn> will blithely continue after
1700 Every time you put more than one shell command (this
1701 includes using a loop) in a makefile command you
1702 must make sure that errors are trapped. For
1703 simple compound commands, such as changing directory and
1704 then running a program, using <tt>&&</tt> rather
1705 than semicolon as a command separator is sufficient. For
1706 more complex commands including most loops and
1707 conditionals you should include a separate <tt>set -e</tt>
1708 command at the start of every makefile command that's
1709 actually one of these miniature shell scripts.
1713 <sect id="timestamps">
1714 <heading>Time Stamps</heading>
1716 Maintainers should preserve the modification times of the
1717 upstream source files in a package, as far as is reasonably
1719 The rationale is that there is some information conveyed
1720 by knowing the age of the file, for example, you could
1721 recognize that some documentation is very old by looking
1722 at the modification time, so it would be nice if the
1723 modification time of the upstream source would be
1729 <sect id="restrictions">
1730 <heading>Restrictions on objects in source packages</heading>
1733 The source package may not contain any hard links<footnote>
1735 This is not currently detected when building source
1736 packages, but only when extracting
1740 Hard links may be permitted at some point in the
1741 future, but would require a fair amount of
1744 </footnote>, device special files, sockets or setuid or
1745 setgid files.<footnote>
1746 Setgid directories are allowed.
1751 <sect id="debianrules">
1752 <heading>Main building script: <file>debian/rules</file></heading>
1755 This file must be an executable makefile, and contains the
1756 package-specific recipes for compiling the package and
1757 building binary package(s) from the source.
1761 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1762 so that it can be invoked by saying its name rather than
1763 invoking <prgn>make</prgn> explicitly. That is, invoking
1764 either of <tt>make -f debian/rules <em>args...</em></tt>
1765 or <tt>./debian/rules <em>args...</em></tt> must result in
1770 Since an interactive <file>debian/rules</file> script makes it
1771 impossible to auto-compile that package and also makes it
1772 hard for other people to reproduce the same binary
1773 package, all <em>required targets</em> must be
1774 non-interactive. At a minimum, required targets are the
1775 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1776 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1777 <em>binary-indep</em>, and <em>build</em>. It also follows
1778 that any target that these targets depend on must also be
1783 The targets are as follows (required unless stated otherwise):
1785 <tag><tt>build</tt></tag>
1788 The <tt>build</tt> target should perform all the
1789 configuration and compilation of the package.
1790 If a package has an interactive pre-build
1791 configuration routine, the Debianized source package
1792 must either be built after this has taken place (so
1793 that the binary package can be built without rerunning
1794 the configuration) or the configuration routine
1795 modified to become non-interactive. (The latter is
1796 preferable if there are architecture-specific features
1797 detected by the configuration routine.)
1801 For some packages, notably ones where the same
1802 source tree is compiled in different ways to produce
1803 two binary packages, the <tt>build</tt> target
1804 does not make much sense. For these packages it is
1805 good enough to provide two (or more) targets
1806 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1807 for each of the ways of building the package, and a
1808 <tt>build</tt> target that does nothing. The
1809 <tt>binary</tt> target will have to build the
1810 package in each of the possible ways and make the
1811 binary package out of each.
1815 The <tt>build</tt> target must not do anything
1816 that might require root privilege.
1820 The <tt>build</tt> target may need to run the
1821 <tt>clean</tt> target first - see below.
1825 When a package has a configuration and build routine
1826 which takes a long time, or when the makefiles are
1827 poorly designed, or when <tt>build</tt> needs to
1828 run <tt>clean</tt> first, it is a good idea to
1829 <tt>touch build</tt> when the build process is
1830 complete. This will ensure that if <tt>debian/rules
1831 build</tt> is run again it will not rebuild the whole
1833 Another common way to do this is for <tt>build</tt>
1834 to depend on <prgn>build-stamp</prgn> and to do
1835 nothing else, and for the <prgn>build-stamp</prgn>
1836 target to do the building and to <tt>touch
1837 build-stamp</tt> on completion. This is
1838 especially useful if the build routine creates a
1839 file or directory called <tt>build</tt>; in such a
1840 case, <tt>build</tt> will need to be listed as
1841 a phony target (i.e., as a dependency of the
1842 <tt>.PHONY</tt> target). See the documentation of
1843 <prgn>make</prgn> for more information on phony
1849 <tag><tt>build-arch</tt> (optional),
1850 <tt>build-indep</tt> (optional)
1854 A package may also provide both of the targets
1855 <tt>build-arch</tt> and <tt>build-indep</tt>.
1856 The <tt>build-arch</tt> target, if provided, should
1857 perform all the configuration and compilation required for
1858 producing all architecture-dependant binary packages
1859 (those packages for which the body of the
1860 <tt>Architecture</tt> field in <tt>debian/control</tt> is
1861 not <tt>all</tt>). Similarly, the <tt>build-indep</tt>
1862 target, if provided, should perform all the configuration
1863 and compilation required for producing all
1864 architecture-independent binary packages (those packages
1865 for which the body of the <tt>Architecture</tt> field
1866 in <tt>debian/control</tt> is <tt>all</tt>).
1867 The <tt>build</tt> target should depend on those of the
1868 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1869 are provided in the rules file.<footnote>
1870 The intent of this split is so that binary-only builds
1871 need not install the dependencies required for
1872 the <tt>build-indep</tt> target. However, this is not
1873 yet used in practice since <tt>dpkg-buildpackage
1874 -B</tt>, and therefore the autobuilders,
1875 invoke <tt>build</tt> rather than <tt>build-arch</tt>
1876 due to the difficulties in determining whether the
1877 optional <tt>build-arch</tt> target exists.
1882 If one or both of the targets <tt>build-arch</tt> and
1883 <tt>build-indep</tt> are not provided, then invoking
1884 <file>debian/rules</file> with one of the not-provided
1885 targets as arguments should produce a exit status code
1886 of 2. Usually this is provided automatically by make
1887 if the target is missing.
1891 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1892 must not do anything that might require root privilege.
1896 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1897 <tt>binary-indep</tt>
1901 The <tt>binary</tt> target must be all that is
1902 necessary for the user to build the binary package(s)
1903 produced from this source package. It is
1904 split into two parts: <prgn>binary-arch</prgn> builds
1905 the binary packages which are specific to a particular
1906 architecture, and <tt>binary-indep</tt> builds
1907 those which are not.
1910 <tt>binary</tt> may be (and commonly is) a target with
1911 no commands which simply depends on
1912 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1915 Both <tt>binary-*</tt> targets should depend on the
1916 <tt>build</tt> target, or on the appropriate
1917 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1918 provided, so that the package is built if it has not
1919 been already. It should then create the relevant
1920 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1921 make their control files and <prgn>dpkg-deb</prgn> to
1922 build them and place them in the parent of the top
1927 Both the <tt>binary-arch</tt> and
1928 <tt>binary-indep</tt> targets <em>must</em> exist.
1929 If one of them has nothing to do (which will always be
1930 the case if the source generates only a single binary
1931 package, whether architecture-dependent or not), it
1932 must still exist and must always succeed.
1936 The <tt>binary</tt> targets must be invoked as
1938 The <prgn>fakeroot</prgn> package often allows one
1939 to build a package correctly even without being
1945 <tag><tt>clean</tt></tag>
1948 This must undo any effects that the <tt>build</tt>
1949 and <tt>binary</tt> targets may have had, except
1950 that it should leave alone any output files created in
1951 the parent directory by a run of a <tt>binary</tt>
1956 If a <tt>build</tt> file is touched at the end of
1957 the <tt>build</tt> target, as suggested above, it
1958 should be removed as the first action that
1959 <tt>clean</tt> performs, so that running
1960 <tt>build</tt> again after an interrupted
1961 <tt>clean</tt> doesn't think that everything is
1966 The <tt>clean</tt> target may need to be
1967 invoked as root if <tt>binary</tt> has been
1968 invoked since the last <tt>clean</tt>, or if
1969 <tt>build</tt> has been invoked as root (since
1970 <tt>build</tt> may create directories, for
1975 <tag><tt>get-orig-source</tt> (optional)</tag>
1978 This target fetches the most recent version of the
1979 original source package from a canonical archive site
1980 (via FTP or WWW, for example), does any necessary
1981 rearrangement to turn it into the original source
1982 tar file format described below, and leaves it in the
1987 This target may be invoked in any directory, and
1988 should take care to clean up any temporary files it
1993 This target is optional, but providing it if
1994 possible is a good idea.
1998 <tag><tt>patch</tt> (optional)</tag>
2001 This target performs whatever additional actions are
2002 required to make the source ready for editing (unpacking
2003 additional upstream archives, applying patches, etc.).
2004 It is recommended to be implemented for any package where
2005 <tt>dpkg-source -x</tt> does not result in source ready
2006 for additional modification. See
2007 <ref id="readmesource">.
2013 The <tt>build</tt>, <tt>binary</tt> and
2014 <tt>clean</tt> targets must be invoked with the current
2015 directory being the package's top-level directory.
2020 Additional targets may exist in <file>debian/rules</file>,
2021 either as published or undocumented interfaces or for the
2022 package's internal use.
2026 The architectures we build on and build for are determined
2027 by <prgn>make</prgn> variables using the utility
2028 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
2029 You can determine the
2030 Debian architecture and the GNU style architecture
2031 specification string for the build machine (the machine type
2032 we are building on) as well as for the host machine (the
2033 machine type we are building for). Here is a list of
2034 supported <prgn>make</prgn> variables:
2035 <list compact="compact">
2037 <tt>DEB_*_ARCH</tt> (the Debian architecture)
2040 <tt>DEB_*_ARCH_CPU</tt> (the Debian CPU name)
2043 <tt>DEB_*_ARCH_OS</tt> (the Debian System name)
2046 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2047 specification string)
2050 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2051 <tt>DEB_*_GNU_TYPE</tt>)
2054 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2055 <tt>DEB_*_GNU_TYPE</tt>)
2057 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2058 the build machine or <tt>HOST</tt> for specification of the
2063 Backward compatibility can be provided in the rules file
2064 by setting the needed variables to suitable default
2065 values; please refer to the documentation of
2066 <prgn>dpkg-architecture</prgn> for details.
2070 It is important to understand that the <tt>DEB_*_ARCH</tt>
2071 string only determines which Debian architecture we are
2072 building on or for. It should not be used to get the CPU
2073 or system information; the <tt>DEB_*_ARCH_CPU</tt> and
2074 <tt>DEB_*_ARCH_OS</tt> variables should be used for that.
2075 GNU style variables should generally only be used with upstream
2079 <sect1 id="debianrules-options">
2080 <heading><file>debian/rules</file> and
2081 <tt>DEB_BUILD_OPTIONS</tt></heading>
2084 Supporting the standardized environment variable
2085 <tt>DEB_BUILD_OPTIONS</tt> is recommended. This variable can
2086 contain several flags to change how a package is compiled and
2087 built. Each flag must be in the form <var>flag</var> or
2088 <var>flag</var>=<var>options</var>. If multiple flags are
2089 given, they must be separated by whitespace.<footnote>
2090 Some packages support any delimiter, but whitespace is the
2091 easiest to parse inside a makefile and avoids ambiguity with
2092 flag values that contain commas.
2094 <var>flag</var> must start with a lowercase letter
2095 (<tt>a-z</tt>) and consist only of lowercase letters,
2096 numbers (<tt>0-9</tt>), and the characters
2097 <tt>-</tt> and <tt>_</tt> (hyphen and underscore).
2098 <var>options</var> must not contain whitespace. The same
2099 tag should not be given multiple times with conflicting
2100 values. Package maintainers may assume that
2101 <tt>DEB_BUILD_OPTIONS</tt> will not contain conflicting tags.
2105 The meaning of the following tags has been standardized:
2109 This tag says to not run any build-time test suite
2110 provided by the package.
2114 The presence of this tag means that the package should
2115 be compiled with a minimum of optimization. For C
2116 programs, it is best to add <tt>-O0</tt> to
2117 <tt>CFLAGS</tt> (although this is usually the default).
2118 Some programs might fail to build or run at this level
2119 of optimization; it may be necessary to use
2120 <tt>-O1</tt>, for example.
2124 This tag means that the debugging symbols should not be
2125 stripped from the binary during installation, so that
2126 debugging information may be included in the package.
2128 <tag>parallel=n</tag>
2130 This tag means that the package should be built using up
2131 to <tt>n</tt> parallel processes if the package build
2132 system supports this.<footnote>
2133 Packages built with <tt>make</tt> can often implement
2134 this by passing the <tt>-j</tt><var>n</var> option to
2137 If the package build system does not support parallel
2138 builds, this string must be ignored. If the package
2139 build system only supports a lower level of concurrency
2140 than <var>n</var>, the package should be built using as
2141 many parallel processes as the package build system
2142 supports. It is up to the package maintainer to decide
2143 whether the package build times are long enough and the
2144 package build system is robust enough to make supporting
2145 parallel builds worthwhile.
2151 Unknown flags must be ignored by <file>debian/rules</file>.
2155 The following makefile snippet is an example of how one may
2156 implement the build options; you will probably have to
2157 massage this example in order to make it work for your
2159 <example compact="compact">
2162 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
2163 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
2164 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
2165 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
2167 ifneq (,$(filter noopt,$(DEB_BUILD_OPTIONS)))
2172 ifeq (,$(filter nostrip,$(DEB_BUILD_OPTIONS)))
2173 INSTALL_PROGRAM += -s
2175 ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2176 NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2177 MAKEFLAGS += -j$(NUMJOBS)
2182 ifeq (,$(filter nocheck,$(DEB_BUILD_OPTIONS)))
2183 # Code to run the package test suite.
2190 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2191 <sect id="substvars">
2192 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2195 When <prgn>dpkg-gencontrol</prgn>,
2196 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2197 generate control files they perform variable substitutions
2198 on their output just before writing it. Variable
2199 substitutions have the form <tt>${<var>variable</var>}</tt>.
2200 The optional file <file>debian/substvars</file> contains
2201 variable substitutions to be used; variables can also be set
2202 directly from <file>debian/rules</file> using the <tt>-V</tt>
2203 option to the source packaging commands, and certain
2204 predefined variables are also available.
2208 The <file>debian/substvars</file> file is usually generated and
2209 modified dynamically by <file>debian/rules</file> targets, in
2210 which case it must be removed by the <tt>clean</tt> target.
2214 See <manref name="deb-substvars" section="5"> for full
2215 details about source variable substitutions, including the
2216 format of <file>debian/substvars</file>.</p>
2219 <sect id="debianwatch">
2220 <heading>Optional upstream source location: <file>debian/watch</file></heading>
2223 This is an optional, recommended control file for the
2224 <tt>uscan</tt> utility which defines how to automatically
2225 scan ftp or http sites for newly available updates of the
2226 package. This is used by <url id="
2227 http://dehs.alioth.debian.org/"> and other Debian QA tools
2228 to help with quality control and maintenance of the
2229 distribution as a whole.
2234 <sect id="debianfiles">
2235 <heading>Generated files list: <file>debian/files</file></heading>
2238 This file is not a permanent part of the source tree; it
2239 is used while building packages to record which files are
2240 being generated. <prgn>dpkg-genchanges</prgn> uses it
2241 when it generates a <file>.changes</file> file.
2245 It should not exist in a shipped source package, and so it
2246 (and any backup files or temporary files such as
2247 <file>files.new</file><footnote>
2248 <file>files.new</file> is used as a temporary file by
2249 <prgn>dpkg-gencontrol</prgn> and
2250 <prgn>dpkg-distaddfile</prgn> - they write a new
2251 version of <tt>files</tt> here before renaming it,
2252 to avoid leaving a corrupted copy if an error
2254 </footnote>) should be removed by the
2255 <tt>clean</tt> target. It may also be wise to
2256 ensure a fresh start by emptying or removing it at the
2257 start of the <tt>binary</tt> target.
2261 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2262 package, it adds an entry to <file>debian/files</file> for the
2263 <file>.deb</file> file that will be created when <tt>dpkg-deb
2264 --build</tt> is run for that binary package. So for most
2265 packages all that needs to be done with this file is to
2266 delete it in the <tt>clean</tt> target.
2270 If a package upload includes files besides the source
2271 package and any binary packages whose control files were
2272 made with <prgn>dpkg-gencontrol</prgn> then they should be
2273 placed in the parent of the package's top-level directory
2274 and <prgn>dpkg-distaddfile</prgn> should be called to add
2275 the file to the list in <file>debian/files</file>.</p>
2278 <sect id="embeddedfiles">
2279 <heading>Convenience copies of code</heading>
2282 Some software packages include in their distribution convenience
2283 copies of code from other software packages, generally so that
2284 users compiling from source don't have to download multiple
2285 packages. Debian packages should not make use of these
2286 convenience copies unless the included package is explicitly
2287 intended to be used in this way.<footnote>
2288 For example, parts of the GNU build system work like this.
2290 If the included code is already in the Debian archive in the
2291 form of a library, the Debian packaging should ensure that
2292 binary packages reference the libraries already in Debian and
2293 the convenience copy is not used. If the included code is not
2294 already in Debian, it should be packaged separately as a
2295 prerequisite if possible.
2297 Having multiple copies of the same code in Debian is
2298 inefficient, often creates either static linking or shared
2299 library conflicts, and, most importantly, increases the
2300 difficulty of handling security vulnerabilities in the
2306 <sect id="readmesource">
2307 <heading>Source package handling:
2308 <file>debian/README.source</file></heading>
2311 If running <prgn>dpkg-source -x</prgn> on a source package
2312 doesn't produce the source of the package, ready for editing,
2313 and allow one to make changes and run
2314 <prgn>dpkg-buildpackage</prgn> to produce a modified package
2315 without taking any additional steps, creating a
2316 <file>debian/README.source</file> documentation file is
2317 recommended. This file should explain how to do all of the
2320 <item>Generate the fully patched source, in a form ready for
2321 editing, that would be built to create Debian
2322 packages. Doing this with a <tt>patch</tt> target in
2323 <file>debian/rules</file> is recommended; see
2324 <ref id="debianrules">.</item>
2325 <item>Modify the source and save those modifications so that
2326 they will be applied when building the package.</item>
2327 <item>Remove source modifications that are currently being
2328 applied when building the package.</item>
2329 <item>Optionally, document what steps are necessary to
2330 upgrade the Debian source package to a new upstream version,
2331 if applicable.</item>
2333 This explanation should include specific commands and mention
2334 any additional required Debian packages. It should not assume
2335 familiarity with any specific Debian packaging system or patch
2340 This explanation may refer to a documentation file installed by
2341 one of the package's build dependencies provided that the
2342 referenced documentation clearly explains these tasks and is not
2343 a general reference manual.
2347 <file>debian/README.source</file> may also include any other
2348 information that would be helpful to someone modifying the
2349 source package. Even if the package doesn't fit the above
2350 description, maintainers are encouraged to document in a
2351 <file>debian/README.source</file> file any source package with a
2352 particularly complex or unintuitive source layout or build
2353 system (for example, a package that builds the same source
2354 multiple times to generate different binary packages).
2360 <chapt id="controlfields">
2361 <heading>Control files and their fields</heading>
2364 The package management system manipulates data represented in
2365 a common format, known as <em>control data</em>, stored in
2366 <em>control files</em>.
2367 Control files are used for source packages, binary packages and
2368 the <file>.changes</file> files which control the installation
2369 of uploaded files<footnote>
2370 <prgn>dpkg</prgn>'s internal databases are in a similar
2375 <sect id="controlsyntax">
2376 <heading>Syntax of control files</heading>
2379 A control file consists of one or more paragraphs of
2381 The paragraphs are also sometimes referred to as stanzas.
2383 The paragraphs are separated by blank lines. Some control
2384 files allow only one paragraph; others allow several, in
2385 which case each paragraph usually refers to a different
2386 package. (For example, in source packages, the first
2387 paragraph refers to the source package, and later paragraphs
2388 refer to binary packages generated from the source.)
2392 Each paragraph consists of a series of data fields; each
2393 field consists of the field name, followed by a colon and
2394 then the data/value associated with that field. It ends at
2395 the end of the (logical) line. Horizontal whitespace
2396 (spaces and tabs) may occur immediately before or after the
2397 value and is ignored there; it is conventional to put a
2398 single space after the colon. For example, a field might
2400 <example compact="compact">
2403 the field name is <tt>Package</tt> and the field value
2408 A paragraph must not contain more than one instance of a
2409 particular field name.
2413 Many fields' values may span several lines; in this case
2414 each continuation line must start with a space or a tab.
2415 Any trailing spaces or tabs at the end of individual
2416 lines of a field value are ignored.
2420 In fields where it is specified that lines may not wrap,
2421 only a single line of data is allowed and whitespace is not
2422 significant in a field body. Whitespace must not appear
2423 inside names (of packages, architectures, files or anything
2424 else) or version numbers, or between the characters of
2425 multi-character version relationships.
2429 Field names are not case-sensitive, but it is usual to
2430 capitalize the field names using mixed case as shown below.
2431 Field values are case-sensitive unless the description of the
2432 field says otherwise.
2436 Blank lines, or lines consisting only of spaces and tabs,
2437 are not allowed within field values or between fields - that
2438 would mean a new paragraph.
2442 All control files must be encoded in UTF-8.
2446 <sect id="sourcecontrolfiles">
2447 <heading>Source package control files -- <file>debian/control</file></heading>
2450 The <file>debian/control</file> file contains the most vital
2451 (and version-independent) information about the source package
2452 and about the binary packages it creates.
2456 The first paragraph of the control file contains information about
2457 the source package in general. The subsequent sets each describe a
2458 binary package that the source tree builds.
2462 The fields in the general paragraph (the first one, for the source
2465 <list compact="compact">
2466 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2467 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2468 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2469 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2470 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2471 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2472 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2473 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2478 The fields in the binary package paragraphs are:
2480 <list compact="compact">
2481 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2482 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2483 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2484 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2485 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2486 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2487 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2488 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2493 The syntax and semantics of the fields are described below.
2497 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2498 generate control files for binary packages (see below), by
2499 <prgn>dpkg-genchanges</prgn> to generate the
2500 <tt>.changes</tt> file to accompany the upload, and by
2501 <prgn>dpkg-source</prgn> when it creates the
2502 <file>.dsc</file> source control file as part of a source
2503 archive. Many fields are permitted to span multiple lines in
2504 <file>debian/control</file> but not in any other control
2505 file. These tools are responsible for removing the line
2506 breaks from such fields when using fields from
2507 <file>debian/control</file> to generate other control files.
2511 The fields here may contain variable references - their
2512 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2513 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2514 when they generate output control files.
2515 See <ref id="substvars"> for details.
2519 In addition to the control file syntax described <qref
2520 id="controlsyntax">above</qref>, this file may also contain
2521 comment lines starting with <tt>#</tt> without any preceding
2522 whitespace. All such lines are ignored, even in the middle of
2523 continuation lines for a multiline field, and do not end a
2529 <sect id="binarycontrolfiles">
2530 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2533 The <file>DEBIAN/control</file> file contains the most vital
2534 (and version-dependent) information about a binary package.
2538 The fields in this file are:
2540 <list compact="compact">
2541 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2542 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2543 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2544 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2545 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2546 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2547 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2548 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2549 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2550 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2551 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2552 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2557 <sect id="debiansourcecontrolfiles">
2558 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2561 This file contains a series of fields, identified and
2562 separated just like the fields in the control file of
2563 a binary package. The fields are listed below; their
2564 syntax is described above, in <ref id="pkg-controlfields">.
2566 <list compact="compact">
2567 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2568 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2569 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2570 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2571 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2572 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2573 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2574 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2575 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2576 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2577 <item><qref id="f-Checksums"><tt>Checksums-Sha1</tt>
2578 and <tt>Checksums-Sha256</tt> (recommended)</item>
2579 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2584 The source package control file is generated by
2585 <prgn>dpkg-source</prgn> when it builds the source
2586 archive, from other files in the source package,
2587 described above. When unpacking, it is checked against
2588 the files and directories in the other parts of the
2594 <sect id="debianchangesfiles">
2595 <heading>Debian changes files -- <file>.changes</file></heading>
2598 The .changes files are used by the Debian archive maintenance
2599 software to process updates to packages. They contain one
2600 paragraph which contains information from the
2601 <tt>debian/control</tt> file and other data about the
2602 source package gathered via <tt>debian/changelog</tt>
2603 and <tt>debian/rules</tt>.
2607 The fields in this file are:
2609 <list compact="compact">
2610 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2611 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2612 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2613 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2614 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2615 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2616 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2617 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2618 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2619 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2620 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2621 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2622 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2623 <item><qref id="f-Checksums"><tt>Checksums-Sha1</tt>
2624 and <tt>Checksums-Sha256</tt> (recommended)</item>
2625 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2630 <sect id="controlfieldslist">
2631 <heading>List of fields</heading>
2633 <sect1 id="f-Source">
2634 <heading><tt>Source</tt></heading>
2637 This field identifies the source package name.
2641 In <file>debian/control</file> or a <file>.dsc</file> file,
2642 this field must contain only the name of the source package.
2646 In a binary package control file or a <file>.changes</file>
2647 file, the source package name may be followed by a version
2648 number in parentheses<footnote>
2649 It is customary to leave a space after the package name
2650 if a version number is specified.
2652 This version number may be omitted (and is, by
2653 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2654 the <tt>Version</tt> field of the binary package in
2655 question. The field itself may be omitted from a binary
2656 package control file when the source package has the same
2657 name and version as the binary package.
2661 Package names (both source and binary,
2662 see <ref id="f-Package">) must consist only of lower case
2663 letters (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus
2664 (<tt>+</tt>) and minus (<tt>-</tt>) signs, and periods
2665 (<tt>.</tt>). They must be at least two characters long and
2666 must start with an alphanumeric character.
2670 <sect1 id="f-Maintainer">
2671 <heading><tt>Maintainer</tt></heading>
2674 The package maintainer's name and email address. The name
2675 must come first, then the email address inside angle
2676 brackets <tt><></tt> (in RFC822 format).
2680 If the maintainer's name contains a full stop then the
2681 whole field will not work directly as an email address due
2682 to a misfeature in the syntax specified in RFC822; a
2683 program using this field as an address must check for this
2684 and correct the problem if necessary (for example by
2685 putting the name in round brackets and moving it to the
2686 end, and bringing the email address forward).
2690 <sect1 id="f-Uploaders">
2691 <heading><tt>Uploaders</tt></heading>
2694 List of the names and email addresses of co-maintainers of
2695 the package, if any. If the package has other maintainers
2696 beside the one named in the
2697 <qref id="f-Maintainer">Maintainer field</qref>, their names
2698 and email addresses should be listed here. The format of each
2699 entry is the same as that of the Maintainer field, and
2700 multiple entries must be comma separated. This is an optional
2705 Any parser that interprets the Uploaders field in
2706 <file>debian/control</file> must permit it to span multiple
2707 lines. Line breaks in an Uploaders field that spans multiple
2708 lines are not significant and the semantics of the field are
2709 the same as if the line breaks had not been present.
2713 <sect1 id="f-Changed-By">
2714 <heading><tt>Changed-By</tt></heading>
2717 The name and email address of the person who prepared this
2718 version of the package, usually a maintainer. The syntax is
2719 the same as for the <qref id="f-Maintainer">Maintainer
2724 <sect1 id="f-Section">
2725 <heading><tt>Section</tt></heading>
2728 This field specifies an application area into which the package
2729 has been classified. See <ref id="subsections">.
2733 When it appears in the <file>debian/control</file> file,
2734 it gives the value for the subfield of the same name in
2735 the <tt>Files</tt> field of the <file>.changes</file> file.
2736 It also gives the default for the same field in the binary
2741 <sect1 id="f-Priority">
2742 <heading><tt>Priority</tt></heading>
2745 This field represents how important it is that the user
2746 have the package installed. See <ref id="priorities">.
2750 When it appears in the <file>debian/control</file> file,
2751 it gives the value for the subfield of the same name in
2752 the <tt>Files</tt> field of the <file>.changes</file> file.
2753 It also gives the default for the same field in the binary
2758 <sect1 id="f-Package">
2759 <heading><tt>Package</tt></heading>
2762 The name of the binary package.
2766 Binary package names must follow the same syntax and
2767 restrictions as source package names. See <ref id="f-Source">
2772 <sect1 id="f-Architecture">
2773 <heading><tt>Architecture</tt></heading>
2776 Depending on context and the control file used, the
2777 <tt>Architecture</tt> field can include the following sets of
2781 A unique single word identifying a Debian machine
2782 architecture as described in <ref id="arch-spec">.
2785 An architecture wildcard identifying a set of Debian
2786 machine architectures, see <ref id="arch-wildcard-spec">.
2787 <tt>any</tt> matches all Debian machine architectures
2788 and is the most frequently used.
2791 <tt>all</tt>, which indicates an
2792 architecture-independent package.
2795 <tt>source</tt>, which indicates a source package.
2801 In the main <file>debian/control</file> file in the source
2802 package, this field may contain the special
2803 value <tt>all</tt>, the special architecture
2804 wildcard <tt>any</tt>, or a list of specific and wildcard
2805 architectures separated by spaces. If <tt>all</tt>
2806 or <tt>any</tt> appears, that value must be the entire
2807 contents of the field. Most packages will use
2808 either <tt>all</tt> or <tt>any</tt>.
2812 Specifying a specific list of architectures indicates that the
2813 source will build an architecture-dependent package only on
2814 architectures included in the list. Specifying a list of
2815 architecture wildcards indicates that the source will build an
2816 architecture-dependent package on only those architectures
2817 that match any of the specified architecture wildcards.
2818 Specifying a list of architectures or architecture wildcards
2819 other than <tt>any</tt> is for the minority of cases where a
2820 program is not portable or is not useful on some
2821 architectures. Where possible, the program should be made
2826 In the source package control file <file>.dsc</file>, this
2827 field may contain either the architecture
2828 wildcard <tt>any</tt> or a list of architectures and
2829 architecture wildcards separated by spaces. If a list is
2830 given, it may include (or consist solely of) the special
2831 value <tt>all</tt>. In other words, in <file>.dsc</file>
2832 files unlike the <file>debian/control</file>, <tt>all</tt> may
2833 occur in combination with specific architectures.
2834 The <tt>Architecture</tt> field in the source package control
2835 file <file>.dsc</file> is generally constructed from
2836 the <tt>Architecture</tt> fields in
2837 the <file>debian/control</file> in the source package.
2841 Specifying <tt>any</tt> indicates that the source package
2842 isn't dependent on any particular architecture and should
2843 compile fine on any one. The produced binary package(s)
2844 will either be specific to whatever the current build
2845 architecture is or will be architecture-independent.
2849 Specifying only <tt>all</tt> indicates that the source package
2850 will only build architecture-independent packages. If this is
2851 the case, <tt>all</tt> must be used rather than <tt>any</tt>;
2852 <tt>any</tt> implies that the source package will build at
2853 least one architecture-dependent package.
2857 Specifying a list of architectures or architecture wildcards
2858 indicates that the source will build an architecture-dependent
2859 package, and will only work correctly on the listed or
2860 matching architectures. If the source package also builds at
2861 least one architecture-independent package, <tt>all</tt> will
2862 also be included in the list.
2866 In a <file>.changes</file> file, the <tt>Architecture</tt>
2867 field lists the architecture(s) of the package(s) currently
2868 being uploaded. This will be a list; if the source for the
2869 package is also being uploaded, the special
2870 entry <tt>source</tt> is also present. <tt>all</tt> will be
2871 present if any architecture-independent packages are being
2872 uploaded. Architecture wildcards such as <tt>any</tt> must
2873 never occur in the <tt>Architecture</tt> field in
2874 the <file>.changes</file> file.
2878 See <ref id="debianrules"> for information on how to get
2879 the architecture for the build process.
2883 <sect1 id="f-Essential">
2884 <heading><tt>Essential</tt></heading>
2887 This is a boolean field which may occur only in the
2888 control file of a binary package or in a per-package fields
2889 paragraph of a main source control data file.
2893 If set to <tt>yes</tt> then the package management system
2894 will refuse to remove the package (upgrading and replacing
2895 it is still possible). The other possible value is <tt>no</tt>,
2896 which is the same as not having the field at all.
2901 <heading>Package interrelationship fields:
2902 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2903 <tt>Recommends</tt>, <tt>Suggests</tt>,
2904 <tt>Breaks</tt>, <tt>Conflicts</tt>,
2905 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2909 These fields describe the package's relationships with
2910 other packages. Their syntax and semantics are described
2911 in <ref id="relationships">.</p>
2914 <sect1 id="f-Standards-Version">
2915 <heading><tt>Standards-Version</tt></heading>
2918 The most recent version of the standards (the policy
2919 manual and associated texts) with which the package
2924 The version number has four components: major and minor
2925 version number and major and minor patch level. When the
2926 standards change in a way that requires every package to
2927 change the major number will be changed. Significant
2928 changes that will require work in many packages will be
2929 signaled by a change to the minor number. The major patch
2930 level will be changed for any change to the meaning of the
2931 standards, however small; the minor patch level will be
2932 changed when only cosmetic, typographical or other edits
2933 are made which neither change the meaning of the document
2934 nor affect the contents of packages.
2938 Thus only the first three components of the policy version
2939 are significant in the <em>Standards-Version</em> control
2940 field, and so either these three components or all four
2941 components may be specified.<footnote>
2942 In the past, people specified the full version number
2943 in the Standards-Version field, for example "2.3.0.0".
2944 Since minor patch-level changes don't introduce new
2945 policy, it was thought it would be better to relax
2946 policy and only require the first 3 components to be
2947 specified, in this example "2.3.0". All four
2948 components may still be used if someone wishes to do so.
2954 <sect1 id="f-Version">
2955 <heading><tt>Version</tt></heading>
2958 The version number of a package. The format is:
2959 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2963 The three components here are:
2965 <tag><var>epoch</var></tag>
2968 This is a single (generally small) unsigned integer. It
2969 may be omitted, in which case zero is assumed. If it is
2970 omitted then the <var>upstream_version</var> may not
2975 It is provided to allow mistakes in the version numbers
2976 of older versions of a package, and also a package's
2977 previous version numbering schemes, to be left behind.
2981 <tag><var>upstream_version</var></tag>
2984 This is the main part of the version number. It is
2985 usually the version number of the original ("upstream")
2986 package from which the <file>.deb</file> file has been made,
2987 if this is applicable. Usually this will be in the same
2988 format as that specified by the upstream author(s);
2989 however, it may need to be reformatted to fit into the
2990 package management system's format and comparison
2995 The comparison behavior of the package management system
2996 with respect to the <var>upstream_version</var> is
2997 described below. The <var>upstream_version</var>
2998 portion of the version number is mandatory.
3002 The <var>upstream_version</var> may contain only
3003 alphanumerics<footnote>
3004 Alphanumerics are <tt>A-Za-z0-9</tt> only.
3006 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
3007 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
3008 tilde) and should start with a digit. If there is no
3009 <var>debian_revision</var> then hyphens are not allowed;
3010 if there is no <var>epoch</var> then colons are not
3015 <tag><var>debian_revision</var></tag>
3018 This part of the version number specifies the version of
3019 the Debian package based on the upstream version. It
3020 may contain only alphanumerics and the characters
3021 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
3022 tilde) and is compared in the same way as the
3023 <var>upstream_version</var> is.
3027 It is optional; if it isn't present then the
3028 <var>upstream_version</var> may not contain a hyphen.
3029 This format represents the case where a piece of
3030 software was written specifically to be turned into a
3031 Debian package, and so there is only one "debianisation"
3032 of it and therefore no revision indication is required.
3036 It is conventional to restart the
3037 <var>debian_revision</var> at <tt>1</tt> each time the
3038 <var>upstream_version</var> is increased.
3042 The package management system will break the version
3043 number apart at the last hyphen in the string (if there
3044 is one) to determine the <var>upstream_version</var> and
3045 <var>debian_revision</var>. The absence of a
3046 <var>debian_revision</var> is equivalent to a
3047 <var>debian_revision</var> of <tt>0</tt>.
3054 When comparing two version numbers, first the <var>epoch</var>
3055 of each are compared, then the <var>upstream_version</var> if
3056 <var>epoch</var> is equal, and then <var>debian_revision</var>
3057 if <var>upstream_version</var> is also equal.
3058 <var>epoch</var> is compared numerically. The
3059 <var>upstream_version</var> and <var>debian_revision</var>
3060 parts are compared by the package management system using the
3061 following algorithm:
3065 The strings are compared from left to right.
3069 First the initial part of each string consisting entirely of
3070 non-digit characters is determined. These two parts (one of
3071 which may be empty) are compared lexically. If a difference
3072 is found it is returned. The lexical comparison is a
3073 comparison of ASCII values modified so that all the letters
3074 sort earlier than all the non-letters and so that a tilde
3075 sorts before anything, even the end of a part. For example,
3076 the following parts are in sorted order from earliest to
3077 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
3078 <tt>a</tt>.<footnote>
3079 One common use of <tt>~</tt> is for upstream pre-releases.
3080 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
3081 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
3086 Then the initial part of the remainder of each string which
3087 consists entirely of digit characters is determined. The
3088 numerical values of these two parts are compared, and any
3089 difference found is returned as the result of the comparison.
3090 For these purposes an empty string (which can only occur at
3091 the end of one or both version strings being compared) counts
3096 These two steps (comparing and removing initial non-digit
3097 strings and initial digit strings) are repeated until a
3098 difference is found or both strings are exhausted.
3102 Note that the purpose of epochs is to allow us to leave behind
3103 mistakes in version numbering, and to cope with situations
3104 where the version numbering scheme changes. It is
3105 <em>not</em> intended to cope with version numbers containing
3106 strings of letters which the package management system cannot
3107 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
3108 silly orderings.<footnote>
3109 The author of this manual has heard of a package whose
3110 versions went <tt>1.1</tt>, <tt>1.2</tt>, <tt>1.3</tt>,
3111 <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>, <tt>2</tt> and so
3117 <sect1 id="f-Description">
3118 <heading><tt>Description</tt></heading>
3121 In a source or binary control file, the <tt>Description</tt>
3122 field contains a description of the binary package, consisting
3123 of two parts, the synopsis or the short description, and the
3124 long description. The field's format is as follows:
3129 Description: <single line synopsis>
3130 <extended description over several lines>
3135 The lines in the extended description can have these formats:
3141 Those starting with a single space are part of a paragraph.
3142 Successive lines of this form will be word-wrapped when
3143 displayed. The leading space will usually be stripped off.
3147 Those starting with two or more spaces. These will be
3148 displayed verbatim. If the display cannot be panned
3149 horizontally, the displaying program will line wrap them "hard"
3150 (i.e., without taking account of word breaks). If it can they
3151 will be allowed to trail off to the right. None, one or two
3152 initial spaces may be deleted, but the number of spaces
3153 deleted from each line will be the same (so that you can have
3154 indenting work correctly, for example).
3158 Those containing a single space followed by a single full stop
3159 character. These are rendered as blank lines. This is the
3160 <em>only</em> way to get a blank line<footnote>
3161 Completely empty lines will not be rendered as blank lines.
3162 Instead, they will cause the parser to think you're starting
3163 a whole new record in the control file, and will therefore
3164 likely abort with an error.
3169 Those containing a space, a full stop and some more characters.
3170 These are for future expansion. Do not use them.
3176 Do not use tab characters. Their effect is not predictable.
3180 See <ref id="descriptions"> for further information on this.
3184 In a <file>.changes</file> file, the <tt>Description</tt>
3185 field contains a summary of the descriptions for the packages
3186 being uploaded. For this case, the first line of the field
3187 value (the part on the same line as <tt>Description:</tt>) is
3188 always empty. The content of the field is expressed as
3189 continuation lines, one line per package. Each line is
3190 indented by one space and contains the name of a binary
3191 package, a space, a hyphen (<tt>-</tt>), a space, and the
3192 short description line from that package.
3196 <sect1 id="f-Distribution">
3197 <heading><tt>Distribution</tt></heading>
3200 In a <file>.changes</file> file or parsed changelog output
3201 this contains the (space-separated) name(s) of the
3202 distribution(s) where this version of the package should
3203 be installed. Valid distributions are determined by the
3204 archive maintainers.<footnote>
3205 Example distribution names in the Debian archive used in
3206 <file>.changes</file> files are:
3207 <taglist compact="compact">
3208 <tag><em>unstable</em></tag>
3210 This distribution value refers to the
3211 <em>developmental</em> part of the Debian distribution
3212 tree. Most new packages, new upstream versions of
3213 packages and bug fixes go into the <em>unstable</em>
3217 <tag><em>experimental</em></tag>
3219 The packages with this distribution value are deemed
3220 by their maintainers to be high risk. Oftentimes they
3221 represent early beta or developmental packages from
3222 various sources that the maintainers want people to
3223 try, but are not ready to be a part of the other parts
3224 of the Debian distribution tree.
3229 Others are used for updating stable releases or for
3230 security uploads. More information is available in the
3231 Debian Developer's Reference, section "The Debian
3235 The Debian archive software only supports listing a single
3236 distribution. Migration of packages to other distributions is
3237 handled outside of the upload process.
3242 <heading><tt>Date</tt></heading>
3245 This field includes the date the package was built or last
3246 edited. It must be in the same format as the <var>date</var>
3247 in a <file>debian/changelog</file> entry.
3251 The value of this field is usually extracted from the
3252 <file>debian/changelog</file> file - see
3253 <ref id="dpkgchangelog">).
3257 <sect1 id="f-Format">
3258 <heading><tt>Format</tt></heading>
3261 This field specifies a format revision for the file.
3262 The most current format described in the Policy Manual
3263 is version <strong>1.5</strong>. The syntax of the
3264 format value is the same as that of a package version
3265 number except that no epoch or Debian revision is allowed
3266 - see <ref id="f-Version">.
3270 <sect1 id="f-Urgency">
3271 <heading><tt>Urgency</tt></heading>
3274 This is a description of how important it is to upgrade to
3275 this version from previous ones. It consists of a single
3276 keyword taking one of the values <tt>low</tt>,
3277 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3278 <tt>critical</tt><footnote>
3279 Other urgency values are supported with configuration
3280 changes in the archive software but are not used in Debian.
3281 The urgency affects how quickly a package will be considered
3282 for inclusion into the <tt>testing</tt> distribution and
3283 gives an indication of the importance of any fixes included
3284 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3285 treated as synonymous.
3286 </footnote> (not case-sensitive) followed by an optional
3287 commentary (separated by a space) which is usually in
3288 parentheses. For example:
3291 Urgency: low (HIGH for users of diversions)
3297 The value of this field is usually extracted from the
3298 <file>debian/changelog</file> file - see
3299 <ref id="dpkgchangelog">.
3303 <sect1 id="f-Changes">
3304 <heading><tt>Changes</tt></heading>
3307 This field contains the human-readable changes data, describing
3308 the differences between the last version and the current one.
3312 The first line of the field value (the part on the same line
3313 as <tt>Changes:</tt>) is always empty. The content of the
3314 field is expressed as continuation lines, with each line
3315 indented by at least one space. Blank lines must be
3316 represented by a line consisting only of a space and a full
3321 The value of this field is usually extracted from the
3322 <file>debian/changelog</file> file - see
3323 <ref id="dpkgchangelog">).
3327 Each version's change information should be preceded by a
3328 "title" line giving at least the version, distribution(s)
3329 and urgency, in a human-readable way.
3333 If data from several versions is being returned the entry
3334 for the most recent version should be returned first, and
3335 entries should be separated by the representation of a
3336 blank line (the "title" line may also be followed by the
3337 representation of a blank line).
3341 <sect1 id="f-Binary">
3342 <heading><tt>Binary</tt></heading>
3345 This field is a list of binary packages. Its syntax and
3346 meaning varies depending on the control file in which it
3351 When it appears in the <file>.dsc</file> file, it lists binary
3352 packages which a source package can produce, separated by
3354 A space after each comma is conventional.
3355 </footnote>. It may span multiple lines. The source package
3356 does not necessarily produce all of these binary packages for
3357 every architecture. The source control file doesn't contain
3358 details of which architectures are appropriate for which of
3359 the binary packages.
3363 When it appears in a <file>.changes</file> file, it lists the
3364 names of the binary packages being uploaded, separated by
3365 whitespace (not commas). It may span multiple lines.
3369 <sect1 id="f-Installed-Size">
3370 <heading><tt>Installed-Size</tt></heading>
3373 This field appears in the control files of binary packages,
3374 and in the <file>Packages</file> files. It gives an estimate
3375 of the total amount of disk space required to install the
3376 named package. Actual installed size may vary based on block
3377 size, file system properties, or actions taken by package
3382 The disk space is given as the integer value of the estimated
3383 installed size in bytes, divided by 1024 and rounded up.
3387 <sect1 id="f-Files">
3388 <heading><tt>Files</tt></heading>
3391 This field contains a list of files with information about
3392 each one. The exact information and syntax varies with
3397 In all cases, Files is a multiline field. The first line of
3398 the field value (the part on the same line as <tt>Files:</tt>)
3399 is always empty. The content of the field is expressed as
3400 continuation lines, one line per file. Each line must be
3401 indented by one space and contain a number of sub-fields,
3402 separated by spaces, as described below.
3406 In the <file>.dsc</file> file, each line contains the MD5
3407 checksum, size and filename of the tar file and (if
3408 applicable) diff file which make up the remainder of the
3409 source package<footnote>
3410 That is, the parts which are not the <tt>.dsc</tt>.
3411 </footnote>. For example:
3414 c6f698f19f2a2aa07dbb9bbda90a2754 571925 example_1.2.orig.tar.gz
3415 938512f08422f3509ff36f125f5873ba 6220 example_1.2-1.diff.gz
3417 The exact forms of the filenames are described
3418 in <ref id="pkg-sourcearchives">.
3422 In the <file>.changes</file> file this contains one line per
3423 file being uploaded. Each line contains the MD5 checksum,
3424 size, section and priority and the filename. For example:
3427 4c31ab7bfc40d3cf49d7811987390357 1428 text extra example_1.2-1.dsc
3428 c6f698f19f2a2aa07dbb9bbda90a2754 571925 text extra example_1.2.orig.tar.gz
3429 938512f08422f3509ff36f125f5873ba 6220 text extra example_1.2-1.diff.gz
3430 7c98fe853b3bbb47a00e5cd129b6cb56 703542 text extra example_1.2-1_i386.deb
3432 The <qref id="f-Section">section</qref>
3433 and <qref id="f-Priority">priority</qref> are the values of
3434 the corresponding fields in the main source control file. If
3435 no section or priority is specified then <tt>-</tt> should be
3436 used, though section and priority values must be specified for
3437 new packages to be installed properly.
3441 The special value <tt>byhand</tt> for the section in a
3442 <tt>.changes</tt> file indicates that the file in question
3443 is not an ordinary package file and must by installed by
3444 hand by the distribution maintainers. If the section is
3445 <tt>byhand</tt> the priority should be <tt>-</tt>.
3449 If a new Debian revision of a package is being shipped and
3450 no new original source archive is being distributed the
3451 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3452 entry for the original source archive
3453 <file><var>package</var>_<var>upstream-version</var>.orig.tar.gz</file>,
3454 but the <file>.changes</file> file should leave it out. In
3455 this case the original source archive on the distribution
3456 site must match exactly, byte-for-byte, the original
3457 source archive which was used to generate the
3458 <file>.dsc</file> file and diff which are being uploaded.</p>
3461 <sect1 id="f-Closes">
3462 <heading><tt>Closes</tt></heading>
3465 A space-separated list of bug report numbers that the upload
3466 governed by the .changes file closes.
3470 <sect1 id="f-Homepage">
3471 <heading><tt>Homepage</tt></heading>
3474 The URL of the web site for this package, preferably (when
3475 applicable) the site from which the original source can be
3476 obtained and any additional upstream documentation or
3477 information may be found. The content of this field is a
3478 simple URL without any surrounding characters such as
3483 <sect1 id="f-Checksums">
3484 <heading><tt>Checksums-Sha1</tt>
3485 and <tt>Checksums-Sha256</tt></heading>
3488 These fields contain a list of files with a checksum and size
3489 for each one. Both <tt>Checksums-Sha1</tt>
3490 and <tt>Checksums-Sha256</tt> have the same syntax and differ
3491 only in the checksum algorithm used: SHA-1
3492 for <tt>Checksums-Sha1</tt> and SHA-256
3493 for <tt>Checksums-Sha256</tt>.
3497 <tt>Checksums-Sha1</tt> and <tt>Checksums-Sha256</tt> are
3498 multiline fields. The first line of the field value (the part
3499 on the same line as <tt>Checksums-Sha1:</tt>
3500 or <tt>Checksums-Sha256:</tt>) is always empty. The content
3501 of the field is expressed as continuation lines, one line per
3502 file. Each line consists of the checksum, a space, the file
3503 size, a space, and the file name. For example (from
3504 a <file>.changes</file> file):
3507 1f418afaa01464e63cc1ee8a66a05f0848bd155c 1276 example_1.0-1.dsc
3508 a0ed1456fad61116f868b1855530dbe948e20f06 171602 example_1.0.orig.tar.gz
3509 5e86ecf0671e113b63388dac81dd8d00e00ef298 6137 example_1.0-1.debian.tar.gz
3510 71a0ff7da0faaf608481195f9cf30974b142c183 548402 example_1.0-1_i386.deb
3512 ac9d57254f7e835bed299926fd51bf6f534597cc3fcc52db01c4bffedae81272 1276 example_1.0-1.dsc
3513 0d123be7f51e61c4bf15e5c492b484054be7e90f3081608a5517007bfb1fd128 171602 example_1.0.orig.tar.gz
3514 f54ae966a5f580571ae7d9ef5e1df0bd42d63e27cb505b27957351a495bc6288 6137 example_1.0-1.debian.tar.gz
3515 3bec05c03974fdecd11d020fc2e8250de8404867a8a2ce865160c250eb723664 548402 example_1.0-1_i386.deb
3520 In the <file>.dsc</file> file, these fields should list all
3521 files that make up the source package. In
3522 the <file>.changes</file> file, these fields should list all
3523 files being uploaded. The list of files in these fields
3524 must match the list of files in the <tt>Files</tt> field.
3531 <heading>User-defined fields</heading>
3534 Additional user-defined fields may be added to the
3535 source package control file. Such fields will be
3536 ignored, and not copied to (for example) binary or
3537 source package control files or upload control files.
3541 If you wish to add additional unsupported fields to
3542 these output files you should use the mechanism
3547 Fields in the main source control information file with
3548 names starting <tt>X</tt>, followed by one or more of
3549 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3550 be copied to the output files. Only the part of the
3551 field name after the hyphen will be used in the output
3552 file. Where the letter <tt>B</tt> is used the field
3553 will appear in binary package control files, where the
3554 letter <tt>S</tt> is used in source package control
3555 files and where <tt>C</tt> is used in upload control
3556 (<tt>.changes</tt>) files.
3560 For example, if the main source information control file
3563 XBS-Comment: I stand between the candle and the star.
3565 then the binary and source package control files will contain the
3568 Comment: I stand between the candle and the star.
3577 <chapt id="maintainerscripts">
3578 <heading>Package maintainer scripts and installation procedure</heading>
3581 <heading>Introduction to package maintainer scripts</heading>
3584 It is possible to supply scripts as part of a package which
3585 the package management system will run for you when your
3586 package is installed, upgraded or removed.
3590 These scripts are the files <prgn>preinst</prgn>,
3591 <prgn>postinst</prgn>, <prgn>prerm</prgn> and
3592 <prgn>postrm</prgn> in the control area of the package.
3593 They must be proper executable files; if they are scripts
3594 (which is recommended), they must start with the usual
3595 <tt>#!</tt> convention. They should be readable and
3596 executable by anyone, and must not be world-writable.
3600 The package management system looks at the exit status from
3601 these scripts. It is important that they exit with a
3602 non-zero status if there is an error, so that the package
3603 management system can stop its processing. For shell
3604 scripts this means that you <em>almost always</em> need to
3605 use <tt>set -e</tt> (this is usually true when writing shell
3606 scripts, in fact). It is also important, of course, that
3607 they exit with a zero status if everything went well.
3611 Additionally, packages interacting with users using
3612 <tt>debconf</tt> in the <prgn>postinst</prgn> script should
3613 install a <prgn>config</prgn> script in the control area,
3614 see <ref id="maintscriptprompt"> for details.
3618 When a package is upgraded a combination of the scripts from
3619 the old and new packages is called during the upgrade
3620 procedure. If your scripts are going to be at all
3621 complicated you need to be aware of this, and may need to
3622 check the arguments to your scripts.
3626 Broadly speaking the <prgn>preinst</prgn> is called before
3627 (a particular version of) a package is installed, and the
3628 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3629 before (a version of) a package is removed and the
3630 <prgn>postrm</prgn> afterwards.
3634 Programs called from maintainer scripts should not normally
3635 have a path prepended to them. Before installation is
3636 started, the package management system checks to see if the
3637 programs <prgn>ldconfig</prgn>,
3638 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3639 and <prgn>update-rc.d</prgn> can be found via the
3640 <tt>PATH</tt> environment variable. Those programs, and any
3641 other program that one would expect to be in the
3642 <tt>PATH</tt>, should thus be invoked without an absolute
3643 pathname. Maintainer scripts should also not reset the
3644 <tt>PATH</tt>, though they might choose to modify it by
3645 prepending or appending package-specific directories. These
3646 considerations really apply to all shell scripts.</p>
3649 <sect id="idempotency">
3650 <heading>Maintainer scripts idempotency</heading>
3653 It is necessary for the error recovery procedures that the
3654 scripts be idempotent. This means that if it is run
3655 successfully, and then it is called again, it doesn't bomb
3656 out or cause any harm, but just ensures that everything is
3657 the way it ought to be. If the first call failed, or
3658 aborted half way through for some reason, the second call
3659 should merely do the things that were left undone the first
3660 time, if any, and exit with a success status if everything
3662 This is so that if an error occurs, the user interrupts
3663 <prgn>dpkg</prgn> or some other unforeseen circumstance
3664 happens you don't leave the user with a badly-broken
3665 package when <prgn>dpkg</prgn> attempts to repeat the
3671 <sect id="controllingterminal">
3672 <heading>Controlling terminal for maintainer scripts</heading>
3675 Maintainer scripts are not guaranteed to run with a controlling
3676 terminal and may not be able to interact with the user. They
3677 must be able to fall back to noninteractive behavior if no
3678 controlling terminal is available. Maintainer scripts that
3679 prompt via a program conforming to the Debian Configuration
3680 Management Specification (see <ref id="maintscriptprompt">) may
3681 assume that program will handle falling back to noninteractive
3686 For high-priority prompts without a reasonable default answer,
3687 maintainer scripts may abort if there is no controlling
3688 terminal. However, this situation should be avoided if at all
3689 possible, since it prevents automated or unattended installs.
3690 In most cases, users will consider this to be a bug in the
3695 <sect id="exitstatus">
3696 <heading>Exit status</heading>
3699 Each script must return a zero exit status for
3700 success, or a nonzero one for failure, since the package
3701 management system looks for the exit status of these scripts
3702 and determines what action to take next based on that datum.
3706 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3711 <list compact="compact">
3713 <var>new-preinst</var> <tt>install</tt>
3716 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3719 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3722 <var>old-preinst</var> <tt>abort-upgrade</tt>
3723 <var>new-version</var>
3728 <list compact="compact">
3730 <var>postinst</var> <tt>configure</tt>
3731 <var>most-recently-configured-version</var>
3734 <var>old-postinst</var> <tt>abort-upgrade</tt>
3735 <var>new-version</var>
3738 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3739 <tt>in-favour</tt> <var>package</var>
3740 <var>new-version</var>
3743 <var>postinst</var> <tt>abort-remove</tt>
3746 <var>deconfigured's-postinst</var>
3747 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3748 <var>failed-install-package</var> <var>version</var>
3749 [<tt>removing</tt> <var>conflicting-package</var>
3755 <list compact="compact">
3757 <var>prerm</var> <tt>remove</tt>
3760 <var>old-prerm</var> <tt>upgrade</tt>
3761 <var>new-version</var>
3764 <var>new-prerm</var> <tt>failed-upgrade</tt>
3765 <var>old-version</var>
3768 <var>conflictor's-prerm</var> <tt>remove</tt>
3769 <tt>in-favour</tt> <var>package</var>
3770 <var>new-version</var>
3773 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3774 <tt>in-favour</tt> <var>package-being-installed</var>
3775 <var>version</var> [<tt>removing</tt>
3776 <var>conflicting-package</var>
3782 <list compact="compact">
3784 <var>postrm</var> <tt>remove</tt>
3787 <var>postrm</var> <tt>purge</tt>
3790 <var>old-postrm</var> <tt>upgrade</tt>
3791 <var>new-version</var>
3794 <var>new-postrm</var> <tt>failed-upgrade</tt>
3795 <var>old-version</var>
3798 <var>new-postrm</var> <tt>abort-install</tt>
3801 <var>new-postrm</var> <tt>abort-install</tt>
3802 <var>old-version</var>
3805 <var>new-postrm</var> <tt>abort-upgrade</tt>
3806 <var>old-version</var>
3809 <var>disappearer's-postrm</var> <tt>disappear</tt>
3810 <var>overwriter</var>
3811 <var>overwriter-version</var>
3817 <sect id="unpackphase">
3818 <heading>Details of unpack phase of installation or upgrade</heading>
3821 The procedure on installation/upgrade/overwrite/disappear
3822 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3823 stage of <tt>dpkg --install</tt>) is as follows. In each
3824 case, if a major error occurs (unless listed below) the
3825 actions are, in general, run backwards - this means that the
3826 maintainer scripts are run with different arguments in
3827 reverse order. These are the "error unwind" calls listed
3834 If a version of the package is already installed, call
3835 <example compact="compact">
3836 <var>old-prerm</var> upgrade <var>new-version</var>
3840 If the script runs but exits with a non-zero
3841 exit status, <prgn>dpkg</prgn> will attempt:
3842 <example compact="compact">
3843 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3845 If this works, the upgrade continues. If this
3846 does not work, the error unwind:
3847 <example compact="compact">
3848 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3850 If this works, then the old-version is
3851 "Installed", if not, the old version is in a
3852 "Half-Configured" state.
3858 If a "conflicting" package is being removed at the same time,
3859 or if any package will be broken (due to <tt>Breaks</tt>):
3862 If <tt>--auto-deconfigure</tt> is
3863 specified, call, for each package to be deconfigured
3864 due to <tt>Breaks</tt>:
3865 <example compact="compact">
3866 <var>deconfigured's-prerm</var> deconfigure \
3867 in-favour <var>package-being-installed</var> <var>version</var>
3870 <example compact="compact">
3871 <var>deconfigured's-postinst</var> abort-deconfigure \
3872 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3874 The deconfigured packages are marked as
3875 requiring configuration, so that if
3876 <tt>--install</tt> is used they will be
3877 configured again if possible.
3880 If any packages depended on a conflicting
3881 package being removed and <tt>--auto-deconfigure</tt> is
3882 specified, call, for each such package:
3883 <example compact="compact">
3884 <var>deconfigured's-prerm</var> deconfigure \
3885 in-favour <var>package-being-installed</var> <var>version</var> \
3886 removing <var>conflicting-package</var> <var>version</var>
3889 <example compact="compact">
3890 <var>deconfigured's-postinst</var> abort-deconfigure \
3891 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3892 removing <var>conflicting-package</var> <var>version</var>
3894 The deconfigured packages are marked as
3895 requiring configuration, so that if
3896 <tt>--install</tt> is used they will be
3897 configured again if possible.
3900 To prepare for removal of each conflicting package, call:
3901 <example compact="compact">
3902 <var>conflictor's-prerm</var> remove \
3903 in-favour <var>package</var> <var>new-version</var>
3906 <example compact="compact">
3907 <var>conflictor's-postinst</var> abort-remove \
3908 in-favour <var>package</var> <var>new-version</var>
3917 If the package is being upgraded, call:
3918 <example compact="compact">
3919 <var>new-preinst</var> upgrade <var>old-version</var>
3921 If this fails, we call:
3923 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3930 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3932 is called. If this works, then the old version
3933 is in an "Installed" state, or else it is left
3934 in an "Unpacked" state.
3939 If it fails, then the old version is left
3940 in an "Half-Installed" state.
3947 Otherwise, if the package had some configuration
3948 files from a previous version installed (i.e., it
3949 is in the "configuration files only" state):
3950 <example compact="compact">
3951 <var>new-preinst</var> install <var>old-version</var>
3955 <var>new-postrm</var> abort-install <var>old-version</var>
3957 If this fails, the package is left in a
3958 "Half-Installed" state, which requires a
3959 reinstall. If it works, the packages is left in
3960 a "Config-Files" state.
3963 Otherwise (i.e., the package was completely purged):
3964 <example compact="compact">
3965 <var>new-preinst</var> install
3968 <example compact="compact">
3969 <var>new-postrm</var> abort-install
3971 If the error-unwind fails, the package is in a
3972 "Half-Installed" phase, and requires a
3973 reinstall. If the error unwind works, the
3974 package is in a not installed state.
3981 The new package's files are unpacked, overwriting any
3982 that may be on the system already, for example any
3983 from the old version of the same package or from
3984 another package. Backups of the old files are kept
3985 temporarily, and if anything goes wrong the package
3986 management system will attempt to put them back as
3987 part of the error unwind.
3991 It is an error for a package to contain files which
3992 are on the system in another package, unless
3993 <tt>Replaces</tt> is used (see <ref id="replaces">).
3995 The following paragraph is not currently the case:
3996 Currently the <tt>- - force-overwrite</tt> flag is
3997 enabled, downgrading it to a warning, but this may not
4003 It is a more serious error for a package to contain a
4004 plain file or other kind of non-directory where another
4005 package has a directory (again, unless
4006 <tt>Replaces</tt> is used). This error can be
4007 overridden if desired using
4008 <tt>--force-overwrite-dir</tt>, but this is not
4013 Packages which overwrite each other's files produce
4014 behavior which, though deterministic, is hard for the
4015 system administrator to understand. It can easily
4016 lead to "missing" programs if, for example, a package
4017 is installed which overwrites a file from another
4018 package, and is then removed again.<footnote>
4019 Part of the problem is due to what is arguably a
4020 bug in <prgn>dpkg</prgn>.
4025 A directory will never be replaced by a symbolic link
4026 to a directory or vice versa; instead, the existing
4027 state (symlink or not) will be left alone and
4028 <prgn>dpkg</prgn> will follow the symlink if there is
4037 If the package is being upgraded, call
4038 <example compact="compact">
4039 <var>old-postrm</var> upgrade <var>new-version</var>
4043 If this fails, <prgn>dpkg</prgn> will attempt:
4044 <example compact="compact">
4045 <var>new-postrm</var> failed-upgrade <var>old-version</var>
4047 If this works, installation continues. If not,
4049 <example compact="compact">
4050 <var>old-preinst</var> abort-upgrade <var>new-version</var>
4052 If this fails, the old version is left in a
4053 "Half-Installed" state. If it works, dpkg now
4055 <example compact="compact">
4056 <var>new-postrm</var> abort-upgrade <var>old-version</var>
4058 If this fails, the old version is left in a
4059 "Half-Installed" state. If it works, dpkg now
4061 <example compact="compact">
4062 <var>old-postinst</var> abort-upgrade <var>new-version</var>
4064 If this fails, the old version is in an
4071 This is the point of no return - if
4072 <prgn>dpkg</prgn> gets this far, it won't back off
4073 past this point if an error occurs. This will
4074 leave the package in a fairly bad state, which
4075 will require a successful re-installation to clear
4076 up, but it's when <prgn>dpkg</prgn> starts doing
4077 things that are irreversible.
4082 Any files which were in the old version of the package
4083 but not in the new are removed.
4087 The new file list replaces the old.
4091 The new maintainer scripts replace the old.
4095 Any packages all of whose files have been overwritten
4096 during the installation, and which aren't required for
4097 dependencies, are considered to have been removed.
4098 For each such package
4101 <prgn>dpkg</prgn> calls:
4102 <example compact="compact">
4103 <var>disappearer's-postrm</var> disappear \
4104 <var>overwriter</var> <var>overwriter-version</var>
4108 The package's maintainer scripts are removed.
4111 It is noted in the status database as being in a
4112 sane state, namely not installed (any conffiles
4113 it may have are ignored, rather than being
4114 removed by <prgn>dpkg</prgn>). Note that
4115 disappearing packages do not have their prerm
4116 called, because <prgn>dpkg</prgn> doesn't know
4117 in advance that the package is going to
4124 Any files in the package we're unpacking that are also
4125 listed in the file lists of other packages are removed
4126 from those lists. (This will lobotomize the file list
4127 of the "conflicting" package if there is one.)
4131 The backup files made during installation, above, are
4137 The new package's status is now sane, and recorded as
4142 Here is another point of no return - if the
4143 conflicting package's removal fails we do not unwind
4144 the rest of the installation; the conflicting package
4145 is left in a half-removed limbo.
4150 If there was a conflicting package we go and do the
4151 removal actions (described below), starting with the
4152 removal of the conflicting package's files (any that
4153 are also in the package being installed have already
4154 been removed from the conflicting package's file list,
4155 and so do not get removed now).
4161 <sect id="configdetails"><heading>Details of configuration</heading>
4164 When we configure a package (this happens with <tt>dpkg
4165 --install</tt> and <tt>dpkg --configure</tt>), we first
4166 update any <tt>conffile</tt>s and then call:
4167 <example compact="compact">
4168 <var>postinst</var> configure <var>most-recently-configured-version</var>
4173 No attempt is made to unwind after errors during
4174 configuration. If the configuration fails, the package is in
4175 a "Failed Config" state, and an error message is generated.
4179 If there is no most recently configured version
4180 <prgn>dpkg</prgn> will pass a null argument.
4183 Historical note: Truly ancient (pre-1997) versions of
4184 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4185 (including the angle brackets) in this case. Even older
4186 ones did not pass a second argument at all, under any
4187 circumstance. Note that upgrades using such an old dpkg
4188 version are unlikely to work for other reasons, even if
4189 this old argument behavior is handled by your postinst script.
4195 <sect id="removedetails"><heading>Details of removal and/or
4196 configuration purging</heading>
4202 <example compact="compact">
4203 <var>prerm</var> remove
4207 If prerm fails during replacement due to conflict
4209 <var>conflictor's-postinst</var> abort-remove \
4210 in-favour <var>package</var> <var>new-version</var>
4214 <var>postinst</var> abort-remove
4218 If this fails, the package is in a "Half-Configured"
4219 state, or else it remains "Installed".
4223 The package's files are removed (except <tt>conffile</tt>s).
4226 <example compact="compact">
4227 <var>postrm</var> remove
4231 If it fails, there's no error unwind, and the package is in
4232 an "Half-Installed" state.
4237 All the maintainer scripts except the <prgn>postrm</prgn>
4242 If we aren't purging the package we stop here. Note
4243 that packages which have no <prgn>postrm</prgn> and no
4244 <tt>conffile</tt>s are automatically purged when
4245 removed, as there is no difference except for the
4246 <prgn>dpkg</prgn> status.
4250 The <tt>conffile</tt>s and any backup files
4251 (<tt>~</tt>-files, <tt>#*#</tt> files,
4252 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4257 <example compact="compact">
4258 <var>postrm</var> purge
4262 If this fails, the package remains in a "Config-Files"
4267 The package's file list is removed.
4276 <chapt id="relationships">
4277 <heading>Declaring relationships between packages</heading>
4279 <sect id="depsyntax">
4280 <heading>Syntax of relationship fields</heading>
4283 These fields all have a uniform syntax. They are a list of
4284 package names separated by commas.
4288 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4289 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4290 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4291 control file fields of the package, which declare
4292 dependencies on other packages, the package names listed may
4293 also include lists of alternative package names, separated
4294 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4295 if any one of the alternative packages is installed, that
4296 part of the dependency is considered to be satisfied.
4300 All of the fields except for <tt>Provides</tt> may restrict
4301 their applicability to particular versions of each named
4302 package. This is done in parentheses after each individual
4303 package name; the parentheses should contain a relation from
4304 the list below followed by a version number, in the format
4305 described in <ref id="f-Version">.
4309 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4310 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4311 strictly earlier, earlier or equal, exactly equal, later or
4312 equal and strictly later, respectively. The deprecated
4313 forms <tt><</tt> and <tt>></tt> were used to mean
4314 earlier/later or equal, rather than strictly earlier/later,
4315 so they should not appear in new packages (though
4316 <prgn>dpkg</prgn> still supports them).
4320 Whitespace may appear at any point in the version
4321 specification subject to the rules in <ref
4322 id="controlsyntax">, and must appear where it's necessary to
4323 disambiguate; it is not otherwise significant. All of the
4324 relationship fields may span multiple lines. For
4325 consistency and in case of future changes to
4326 <prgn>dpkg</prgn> it is recommended that a single space be
4327 used after a version relationship and before a version
4328 number; it is also conventional to put a single space after
4329 each comma, on either side of each vertical bar, and before
4330 each open parenthesis. When wrapping a relationship field, it
4331 is conventional to do so after a comma and before the space
4332 following that comma.
4336 For example, a list of dependencies might appear as:
4337 <example compact="compact">
4340 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4345 All fields that specify build-time relationships
4346 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4347 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
4348 may be restricted to a certain set of architectures. This
4349 is indicated in brackets after each individual package name and
4350 the optional version specification. The brackets enclose a
4351 list of Debian architecture names separated by whitespace.
4352 Exclamation marks may be prepended to each of the names.
4353 (It is not permitted for some names to be prepended with
4354 exclamation marks while others aren't.) If the current Debian
4355 host architecture is not in this list and there are no
4356 exclamation marks in the list, or it is in the list with a
4357 prepended exclamation mark, the package name and the
4358 associated version specification are ignored completely for
4359 the purposes of defining the relationships.
4364 <example compact="compact">
4366 Build-Depends-Indep: texinfo
4367 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4368 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4370 requires <tt>kernel-headers-2.2.10</tt> on all architectures
4371 other than hurd-i386 and requires <tt>hurd-dev</tt> and
4372 <tt>gnumach-dev</tt> only on hurd-i386.
4376 If the architecture-restricted dependency is part of a set of
4377 alternatives using <tt>|</tt>, that alternative is ignored
4378 completely on architectures that do not match the restriction.
4380 <example compact="compact">
4381 Build-Depends: foo [!i386] | bar [!amd64]
4383 is equivalent to <tt>bar</tt> on the i386 architecture, to
4384 <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
4385 bar</tt> on all other architectures.
4389 All fields that specify build-time relationships may also be
4390 restricted to a certain set of architectures using architecture
4391 wildcards. The syntax for declaring such restrictions is the
4392 same as declaring restrictions using a certain set of
4393 architectures without architecture wildcards. For example:
4394 <example compact="compact">
4395 Build-Depends: foo [linux-any], bar [any-i386], baz [!linux-any]
4397 is equivalent to <tt>foo</tt> on architectures using the Linux
4398 kernel and any cpu, <tt>bar</tt> on architectures using any
4399 kernel and an i386 cpu, and <tt>baz</tt> on any architecture
4400 using a kernel other than Linux.
4404 Note that the binary package relationship fields such as
4405 <tt>Depends</tt> appear in one of the binary package
4406 sections of the control file, whereas the build-time
4407 relationships such as <tt>Build-Depends</tt> appear in the
4408 source package section of the control file (which is the
4413 <sect id="binarydeps">
4414 <heading>Binary Dependencies - <tt>Depends</tt>,
4415 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4416 <tt>Pre-Depends</tt>
4420 Packages can declare in their control file that they have
4421 certain relationships to other packages - for example, that
4422 they may not be installed at the same time as certain other
4423 packages, and/or that they depend on the presence of others.
4427 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4428 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4429 <tt>Breaks</tt> and <tt>Conflicts</tt> control file fields.
4430 <tt>Breaks</tt> is described in <ref id="breaks">, and
4431 <tt>Conflicts</tt> is described in <ref id="conflicts">. The
4432 rest are described below.
4436 These seven fields are used to declare a dependency
4437 relationship by one package on another. Except for
4438 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4439 depending (binary) package's control file.
4440 (<tt>Enhances</tt> appears in the recommending package's
4441 control file, and <tt>Breaks</tt> appears in the version of
4442 depended-on package which causes the named package to
4447 A <tt>Depends</tt> field takes effect <em>only</em> when a
4448 package is to be configured. It does not prevent a package
4449 being on the system in an unconfigured state while its
4450 dependencies are unsatisfied, and it is possible to replace
4451 a package whose dependencies are satisfied and which is
4452 properly installed with a different version whose
4453 dependencies are not and cannot be satisfied; when this is
4454 done the depending package will be left unconfigured (since
4455 attempts to configure it will give errors) and will not
4456 function properly. If it is necessary, a
4457 <tt>Pre-Depends</tt> field can be used, which has a partial
4458 effect even when a package is being unpacked, as explained
4459 in detail below. (The other three dependency fields,
4460 <tt>Recommends</tt>, <tt>Suggests</tt> and
4461 <tt>Enhances</tt>, are only used by the various front-ends
4462 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4463 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4467 For this reason packages in an installation run are usually
4468 all unpacked first and all configured later; this gives
4469 later versions of packages with dependencies on later
4470 versions of other packages the opportunity to have their
4471 dependencies satisfied.
4475 In case of circular dependencies, since installation or
4476 removal order honoring the dependency order can't be
4477 established, dependency loops are broken at some point
4478 (based on rules below), and some packages may not be able to
4479 rely on their dependencies being present when being
4480 installed or removed, depending on which side of the break
4481 of the circular dependency loop they happen to be on. If one
4482 of the packages in the loop has no postinst script, then the
4483 cycle will be broken at that package, so as to ensure that
4484 all postinst scripts run with the dependencies properly
4485 configured if this is possible. Otherwise the breaking point
4490 The <tt>Depends</tt> field thus allows package maintainers
4491 to impose an order in which packages should be configured.
4495 The meaning of the five dependency fields is as follows:
4497 <tag><tt>Depends</tt></tag>
4500 This declares an absolute dependency. A package will
4501 not be configured unless all of the packages listed in
4502 its <tt>Depends</tt> field have been correctly
4507 The <tt>Depends</tt> field should be used if the
4508 depended-on package is required for the depending
4509 package to provide a significant amount of
4514 The <tt>Depends</tt> field should also be used if the
4515 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4516 <prgn>postrm</prgn> scripts require the package to be
4517 present in order to run. Note, however, that the
4518 <prgn>postrm</prgn> cannot rely on any non-essential
4519 packages to be present during the <tt>purge</tt>
4523 <tag><tt>Recommends</tt></tag>
4526 This declares a strong, but not absolute, dependency.
4530 The <tt>Recommends</tt> field should list packages
4531 that would be found together with this one in all but
4532 unusual installations.
4536 <tag><tt>Suggests</tt></tag>
4538 This is used to declare that one package may be more
4539 useful with one or more others. Using this field
4540 tells the packaging system and the user that the
4541 listed packages are related to this one and can
4542 perhaps enhance its usefulness, but that installing
4543 this one without them is perfectly reasonable.
4546 <tag><tt>Enhances</tt></tag>
4548 This field is similar to Suggests but works in the
4549 opposite direction. It is used to declare that a
4550 package can enhance the functionality of another
4554 <tag><tt>Pre-Depends</tt></tag>
4557 This field is like <tt>Depends</tt>, except that it
4558 also forces <prgn>dpkg</prgn> to complete installation
4559 of the packages named before even starting the
4560 installation of the package which declares the
4561 pre-dependency, as follows:
4565 When a package declaring a pre-dependency is about to
4566 be <em>unpacked</em> the pre-dependency can be
4567 satisfied if the depended-on package is either fully
4568 configured, <em>or even if</em> the depended-on
4569 package(s) are only unpacked or in the "Half-Configured"
4570 state, provided that they have been configured
4571 correctly at some point in the past (and not removed
4572 or partially removed since). In this case, both the
4573 previously-configured and currently unpacked or
4574 "Half-Configured" versions must satisfy any version
4575 clause in the <tt>Pre-Depends</tt> field.
4579 When the package declaring a pre-dependency is about
4580 to be <em>configured</em>, the pre-dependency will be
4581 treated as a normal <tt>Depends</tt>, that is, it will
4582 be considered satisfied only if the depended-on
4583 package has been correctly configured.
4587 <tt>Pre-Depends</tt> should be used sparingly,
4588 preferably only by packages whose premature upgrade or
4589 installation would hamper the ability of the system to
4590 continue with any upgrade that might be in progress.
4594 <tt>Pre-Depends</tt> are also required if the
4595 <prgn>preinst</prgn> script depends on the named
4596 package. It is best to avoid this situation if
4604 When selecting which level of dependency to use you should
4605 consider how important the depended-on package is to the
4606 functionality of the one declaring the dependency. Some
4607 packages are composed of components of varying degrees of
4608 importance. Such a package should list using
4609 <tt>Depends</tt> the package(s) which are required by the
4610 more important components. The other components'
4611 requirements may be mentioned as Suggestions or
4612 Recommendations, as appropriate to the components' relative
4618 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4621 When one binary package declares that it breaks another,
4622 <prgn>dpkg</prgn> will refuse to allow the package which
4623 declares <tt>Breaks</tt> be installed unless the broken
4624 package is deconfigured first, and it will refuse to
4625 allow the broken package to be reconfigured.
4629 A package will not be regarded as causing breakage merely
4630 because its configuration files are still installed; it must
4631 be at least "Half-Installed".
4635 A special exception is made for packages which declare that
4636 they break their own package name or a virtual package which
4637 they provide (see below): this does not count as a real
4642 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4643 version clause; such a <tt>Breaks</tt> is introduced in the
4644 version of an (implicit or explicit) dependency which
4645 violates an assumption or reveals a bug in earlier versions
4646 of the broken package. This use of <tt>Breaks</tt> will
4647 inform higher-level package management tools that broken
4648 package must be upgraded before the new one.
4652 If the breaking package also overwrites some files from the
4653 older package, it should use <tt>Replaces</tt> (not
4654 <tt>Conflicts</tt>) to ensure this goes smoothly.
4658 <sect id="conflicts">
4659 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4662 When one binary package declares a conflict with another
4663 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4664 refuse to allow them to be installed on the system at the
4669 If one package is to be installed, the other must be removed
4670 first - if the package being installed is marked as
4671 replacing (see <ref id="replaces">) the one on the system,
4672 or the one on the system is marked as deselected, or both
4673 packages are marked <tt>Essential</tt>, then
4674 <prgn>dpkg</prgn> will automatically remove the package
4675 which is causing the conflict, otherwise it will halt the
4676 installation of the new package with an error. This
4677 mechanism is specifically designed to produce an error when
4678 the installed package is <tt>Essential</tt>, but the new
4683 A package will not cause a conflict merely because its
4684 configuration files are still installed; it must be at least
4689 A special exception is made for packages which declare a
4690 conflict with their own package name, or with a virtual
4691 package which they provide (see below): this does not
4692 prevent their installation, and allows a package to conflict
4693 with others providing a replacement for it. You use this
4694 feature when you want the package in question to be the only
4695 package providing some feature.
4699 A <tt>Conflicts</tt> entry should almost never have an
4700 "earlier than" version clause. This would prevent
4701 <prgn>dpkg</prgn> from upgrading or installing the package
4702 which declared such a conflict until the upgrade or removal
4703 of the conflicted-with package had been completed. Instead,
4704 <tt>Breaks</tt> may be used.
4708 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4712 As well as the names of actual ("concrete") packages, the
4713 package relationship fields <tt>Depends</tt>,
4714 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4715 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4716 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4717 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4718 may mention "virtual packages".
4722 A <em>virtual package</em> is one which appears in the
4723 <tt>Provides</tt> control file field of another package.
4724 The effect is as if the package(s) which provide a
4725 particular virtual package name had been listed by name
4726 everywhere the virtual package name appears. (See also <ref
4731 If there are both concrete and virtual packages of the same
4732 name, then the dependency may be satisfied (or the conflict
4733 caused) by either the concrete package with the name in
4734 question or any other concrete package which provides the
4735 virtual package with the name in question. This is so that,
4736 for example, supposing we have
4737 <example compact="compact">
4740 </example> and someone else releases an enhanced version of
4741 the <tt>bar</tt> package they can say:
4742 <example compact="compact">
4746 and the <tt>bar-plus</tt> package will now also satisfy the
4747 dependency for the <tt>foo</tt> package.
4751 If a relationship field has a version number attached
4752 then only real packages will be considered to see whether
4753 the relationship is satisfied (or the prohibition violated,
4754 for a conflict or breakage) - it is assumed that a real
4755 package which provides the virtual package is not of the
4756 "right" version. So, a <tt>Provides</tt> field may not
4757 contain version numbers, and the version number of the
4758 concrete package which provides a particular virtual package
4759 will not be looked at when considering a dependency on or
4760 conflict with the virtual package name.
4764 It is likely that the ability will be added in a future
4765 release of <prgn>dpkg</prgn> to specify a version number for
4766 each virtual package it provides. This feature is not yet
4767 present, however, and is expected to be used only
4772 If you want to specify which of a set of real packages
4773 should be the default to satisfy a particular dependency on
4774 a virtual package, you should list the real package as an
4775 alternative before the virtual one.
4780 <sect id="replaces"><heading>Overwriting files and replacing
4781 packages - <tt>Replaces</tt></heading>
4784 Packages can declare in their control file that they should
4785 overwrite files in certain other packages, or completely
4786 replace other packages. The <tt>Replaces</tt> control file
4787 field has these two distinct purposes.
4790 <sect1><heading>Overwriting files in other packages</heading>
4793 Firstly, as mentioned before, it is usually an error for a
4794 package to contain files which are on the system in
4799 However, if the overwriting package declares that it
4800 <tt>Replaces</tt> the one containing the file being
4801 overwritten, then <prgn>dpkg</prgn> will replace the file
4802 from the old package with that from the new. The file
4803 will no longer be listed as "owned" by the old package.
4807 For example, if a package <package>foo</package> is split
4808 into <package>foo</package> and <package>foo-data</package>
4809 starting at version 1.2-3, <package>foo-data</package> should
4811 <example compact="compact">
4812 Replaces: foo (<< 1.2-3)
4814 in its control file. The package <package>foo</package>
4815 doesn't need any special control fields in this example,
4816 although would generally depend on or
4817 recommend <package>foo-data</package>.
4821 If a package is completely replaced in this way, so that
4822 <prgn>dpkg</prgn> does not know of any files it still
4823 contains, it is considered to have "disappeared". It will
4824 be marked as not wanted on the system (selected for
4825 removal) and not installed. Any <tt>conffile</tt>s
4826 details noted for the package will be ignored, as they
4827 will have been taken over by the overwriting package. The
4828 package's <prgn>postrm</prgn> script will be run with a
4829 special argument to allow the package to do any final
4830 cleanup required. See <ref id="mscriptsinstact">.
4833 Replaces is a one way relationship -- you have to
4834 install the replacing package after the replaced
4841 For this usage of <tt>Replaces</tt>, virtual packages (see
4842 <ref id="virtual">) are not considered when looking at a
4843 <tt>Replaces</tt> field - the packages declared as being
4844 replaced must be mentioned by their real names.
4848 Furthermore, this usage of <tt>Replaces</tt> only takes
4849 effect when both packages are at least partially on the
4850 system at once, so that it can only happen if they do not
4851 conflict or if the conflict has been overridden.
4856 <sect1><heading>Replacing whole packages, forcing their
4860 Secondly, <tt>Replaces</tt> allows the packaging system to
4861 resolve which package should be removed when there is a
4862 conflict - see <ref id="conflicts">. This usage only
4863 takes effect when the two packages <em>do</em> conflict,
4864 so that the two usages of this field do not interfere with
4869 In this situation, the package declared as being replaced
4870 can be a virtual package, so for example, all mail
4871 transport agents (MTAs) would have the following fields in
4872 their control files:
4873 <example compact="compact">
4874 Provides: mail-transport-agent
4875 Conflicts: mail-transport-agent
4876 Replaces: mail-transport-agent
4878 ensuring that only one MTA can be installed at any one
4883 <sect id="sourcebinarydeps">
4884 <heading>Relationships between source and binary packages -
4885 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4886 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4890 Source packages that require certain binary packages to be
4891 installed or absent at the time of building the package
4892 can declare relationships to those binary packages.
4896 This is done using the <tt>Build-Depends</tt>,
4897 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4898 <tt>Build-Conflicts-Indep</tt> control file fields.
4902 Build-dependencies on "build-essential" binary packages can be
4903 omitted. Please see <ref id="pkg-relations"> for more information.
4907 The dependencies and conflicts they define must be satisfied
4908 (as defined earlier for binary packages) in order to invoke
4909 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4911 There is no Build-Depends-Arch; this role is essentially
4912 met with Build-Depends. Anyone building the
4913 <tt>build-indep</tt> and binary-indep<tt></tt> targets is
4914 assumed to be building the whole package, and therefore
4915 installation of all build dependencies is required.
4918 The autobuilders use <tt>dpkg-buildpackage -B</tt>, which
4919 calls <tt>build</tt>, not <tt>build-arch</tt> since it does
4920 not yet know how to check for its existence, and
4921 <tt>binary-arch</tt>. The purpose of the original split
4922 between <tt>Build-Depends</tt> and
4923 <tt>Build-Depends-Indep</tt> was so that the autobuilders
4924 wouldn't need to install extra packages needed only for the
4925 binary-indep targets. But without a build-arch/build-indep
4926 split, this didn't work, since most of the work is done in
4927 the build target, not in the binary target.
4931 <tag><tt>clean</tt>, <tt>build-arch</tt>, and
4932 <tt>binary-arch</tt></tag>
4934 Only the <tt>Build-Depends</tt> and <tt>Build-Conflicts</tt>
4935 fields must be satisfied when these targets are invoked.
4937 <tag><tt>build</tt>, <tt>build-indep</tt>, <tt>binary</tt>,
4938 and <tt>binary-indep</tt></tag>
4940 The <tt>Build-Depends</tt>, <tt>Build-Conflicts</tt>,
4941 <tt>Build-Depends-Indep</tt>, and
4942 <tt>Build-Conflicts-Indep</tt> fields must be satisfied when
4943 these targets are invoked.
4951 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4954 Packages containing shared libraries must be constructed with
4955 a little care to make sure that the shared library is always
4956 available. This is especially important for packages whose
4957 shared libraries are vitally important, such as the C library
4958 (currently <tt>libc6</tt>).
4962 Packages involving shared libraries should be split up into
4963 several binary packages. This section mostly deals with how
4964 this separation is to be accomplished; rules for files within
4965 the shared library packages are in <ref id="libraries"> instead.
4968 <sect id="sharedlibs-runtime">
4969 <heading>Run-time shared libraries</heading>
4972 The run-time shared library needs to be placed in a package
4973 whose name changes whenever the shared object version
4976 Since it is common place to install several versions of a
4977 package that just provides shared libraries, it is a
4978 good idea that the library package should not
4979 contain any extraneous non-versioned files, unless they
4980 happen to be in versioned directories.</p>
4982 The most common mechanism is to place it in a package
4984 <package><var>libraryname</var><var>soversion</var></package>,
4985 where <file><var>soversion</var></file> is the version number
4986 in the soname of the shared library<footnote>
4987 The soname is the shared object name: it's the thing
4988 that has to match exactly between building an executable
4989 and running it for the dynamic linker to be able run the
4990 program. For example, if the soname of the library is
4991 <file>libfoo.so.6</file>, the library package would be
4992 called <file>libfoo6</file>.
4994 Alternatively, if it would be confusing to directly append
4995 <var>soversion</var> to <var>libraryname</var> (e.g. because
4996 <var>libraryname</var> itself ends in a number), you may use
4997 <package><var>libraryname</var>-<var>soversion</var></package> and
4998 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
5003 If you have several shared libraries built from the same
5004 source tree you may lump them all together into a single
5005 shared library package, provided that you change all of
5006 their sonames at once (so that you don't get filename
5007 clashes if you try to install different versions of the
5008 combined shared libraries package).
5012 The package should install the shared libraries under
5013 their normal names. For example, the <package>libgdbm3</package>
5014 package should install <file>libgdbm.so.3.0.0</file> as
5015 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
5016 renamed or re-linked by any <prgn>prerm</prgn> or
5017 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
5018 of renaming things safely without affecting running programs,
5019 and attempts to interfere with this are likely to lead to
5024 Shared libraries should not be installed executable, since
5025 the dynamic linker does not require this and trying to
5026 execute a shared library usually results in a core dump.
5030 The run-time library package should include the symbolic link that
5031 <prgn>ldconfig</prgn> would create for the shared libraries.
5032 For example, the <package>libgdbm3</package> package should include
5033 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
5034 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
5035 linker (for example <prgn>ld.so</prgn> or
5036 <prgn>ld-linux.so.*</prgn>) can find the library between the
5037 time that <prgn>dpkg</prgn> installs it and the time that
5038 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
5040 The package management system requires the library to be
5041 placed before the symbolic link pointing to it in the
5042 <file>.deb</file> file. This is so that when
5043 <prgn>dpkg</prgn> comes to install the symlink
5044 (overwriting the previous symlink pointing at an older
5045 version of the library), the new shared library is already
5046 in place. In the past, this was achieved by creating the
5047 library in the temporary packaging directory before
5048 creating the symlink. Unfortunately, this was not always
5049 effective, since the building of the tar file in the
5050 <file>.deb</file> depended on the behavior of the underlying
5051 file system. Some file systems (such as reiserfs) reorder
5052 the files so that the order of creation is forgotten.
5053 Since version 1.7.0, <prgn>dpkg</prgn>
5054 reorders the files itself as necessary when building a
5055 package. Thus it is no longer important to concern
5056 oneself with the order of file creation.
5060 <sect1 id="ldconfig">
5061 <heading><tt>ldconfig</tt></heading>
5064 Any package installing shared libraries in one of the default
5065 library directories of the dynamic linker (which are currently
5066 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
5067 listed in <file>/etc/ld.so.conf</file><footnote>
5069 <list compact="compact">
5070 <item>/usr/local/lib</item>
5071 <item>/usr/lib/libc5-compat</item>
5072 <item>/lib/libc5-compat</item>
5075 must use <prgn>ldconfig</prgn> to update the shared library
5080 The package maintainer scripts must only call
5081 <prgn>ldconfig</prgn> under these circumstances:
5082 <list compact="compact">
5083 <item>When the <prgn>postinst</prgn> script is run with a
5084 first argument of <tt>configure</tt>, the script must call
5085 <prgn>ldconfig</prgn>, and may optionally invoke
5086 <prgn>ldconfig</prgn> at other times.
5088 <item>When the <prgn>postrm</prgn> script is run with a
5089 first argument of <tt>remove</tt>, the script should call
5090 <prgn>ldconfig</prgn>.
5095 During install or upgrade, the preinst is called before
5096 the new files are installed, so calling "ldconfig" is
5097 pointless. The preinst of an existing package can also be
5098 called if an upgrade fails. However, this happens during
5099 the critical time when a shared libs may exist on-disk
5100 under a temporary name. Thus, it is dangerous and
5101 forbidden by current policy to call "ldconfig" at this
5106 When a package is installed or upgraded, "postinst
5107 configure" runs after the new files are safely on-disk.
5108 Since it is perfectly safe to invoke ldconfig
5109 unconditionally in a postinst, it is OK for a package to
5110 simply put ldconfig in its postinst without checking the
5111 argument. The postinst can also be called to recover from
5112 a failed upgrade. This happens before any new files are
5113 unpacked, so there is no reason to call "ldconfig" at this
5118 For a package that is being removed, prerm is
5119 called with all the files intact, so calling ldconfig is
5120 useless. The other calls to "prerm" happen in the case of
5121 upgrade at a time when all the files of the old package
5122 are on-disk, so again calling "ldconfig" is pointless.
5126 postrm, on the other hand, is called with the "remove"
5127 argument just after the files are removed, so this is
5128 the proper time to call "ldconfig" to notify the system
5129 of the fact that the shared libraries from the package
5130 are removed. The postrm can be called at several other
5131 times. At the time of "postrm purge", "postrm
5132 abort-install", or "postrm abort-upgrade", calling
5133 "ldconfig" is useless because the shared lib files are
5134 not on-disk. However, when "postrm" is invoked with
5135 arguments "upgrade", "failed-upgrade", or "disappear", a
5136 shared lib may exist on-disk under a temporary filename.
5144 <sect id="sharedlibs-support-files">
5145 <heading>Shared library support files</heading>
5148 If your package contains files whose names do not change with
5149 each change in the library shared object version, you must not
5150 put them in the shared library package. Otherwise, several
5151 versions of the shared library cannot be installed at the same
5152 time without filename clashes, making upgrades and transitions
5153 unnecessarily difficult.
5157 It is recommended that supporting files and run-time support
5158 programs that do not need to be invoked manually by users, but
5159 are nevertheless required for the package to function, be placed
5160 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
5161 preferably under <file>/usr/lib/</file><var>package-name</var>.
5162 If the program or file is architecture independent, the
5163 recommendation is for it to be placed in a subdirectory of
5164 <file>/usr/share</file> instead, preferably under
5165 <file>/usr/share/</file><var>package-name</var>. Following the
5166 <var>package-name</var> naming convention ensures that the file
5167 names change when the shared object version changes.
5171 Run-time support programs that use the shared library but are
5172 not required for the library to function or files used by the
5173 shared library that can be used by any version of the shared
5174 library package should instead be put in a separate package.
5175 This package might typically be named
5176 <package><var>libraryname</var>-tools</package>; note the
5177 absence of the <var>soversion</var> in the package name.
5181 Files and support programs only useful when compiling software
5182 against the library should be included in the development
5183 package for the library.<footnote>
5184 For example, a <file><var>package-name</var>-config</file>
5185 script or <package>pkg-config</package> configuration files.
5190 <sect id="sharedlibs-static">
5191 <heading>Static libraries</heading>
5194 The static library (<file><var>libraryname.a</var></file>)
5195 is usually provided in addition to the shared version.
5196 It is placed into the development package (see below).
5200 In some cases, it is acceptable for a library to be
5201 available in static form only; these cases include:
5203 <item>libraries for languages whose shared library support
5204 is immature or unstable</item>
5205 <item>libraries whose interfaces are in flux or under
5206 development (commonly the case when the library's
5207 major version number is zero, or where the ABI breaks
5208 across patchlevels)</item>
5209 <item>libraries which are explicitly intended to be
5210 available only in static form by their upstream
5215 <sect id="sharedlibs-dev">
5216 <heading>Development files</heading>
5219 If there are development files associated with a shared library,
5220 the source package needs to generate a binary development package
5221 named <package><var>libraryname</var><var>soversion</var>-dev</package>,
5222 or if you prefer only to support one development version at a
5223 time, <package><var>libraryname</var>-dev</package>. Installing
5224 the development package must result in installation of all the
5225 development files necessary for compiling programs against that
5226 shared library.<footnote>
5227 This wording allows the development files to be split into
5228 several packages, such as a separate architecture-independent
5229 <package><var>libraryname</var>-headers</package>, provided that
5230 the development package depends on all the required additional
5236 In case several development versions of a library exist, you may
5237 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5238 <ref id="conflicts">) to ensure that the user only installs one
5239 development version at a time (as different development versions are
5240 likely to have the same header files in them, which would cause a
5241 filename clash if both were installed).
5245 The development package should contain a symlink for the associated
5246 shared library without a version number. For example, the
5247 <package>libgdbm-dev</package> package should include a symlink
5248 from <file>/usr/lib/libgdbm.so</file> to
5249 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5250 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5251 <file>libgdbm.so</file> when compiling dynamically.
5255 <sect id="sharedlibs-intradeps">
5256 <heading>Dependencies between the packages of the same library</heading>
5259 Typically the development version should have an exact
5260 version dependency on the runtime library, to make sure that
5261 compilation and linking happens correctly. The
5262 <tt>${binary:Version}</tt> substitution variable can be
5263 useful for this purpose.
5265 Previously, <tt>${Source-Version}</tt> was used, but its name
5266 was confusing and it has been deprecated since dpkg 1.13.19.
5271 <sect id="sharedlibs-shlibdeps">
5272 <heading>Dependencies between the library and other packages -
5273 the <tt>shlibs</tt> system</heading>
5276 If a package contains a binary or library which links to a
5277 shared library, we must ensure that when the package is
5278 installed on the system, all of the libraries needed are
5279 also installed. This requirement led to the creation of the
5280 <tt>shlibs</tt> system, which is very simple in its design:
5281 any package which <em>provides</em> a shared library also
5282 provides information on the package dependencies required to
5283 ensure the presence of this library, and any package which
5284 <em>uses</em> a shared library uses this information to
5285 determine the dependencies it requires. The files which
5286 contain the mapping from shared libraries to the necessary
5287 dependency information are called <file>shlibs</file> files.
5291 Thus, when a package is built which contains any shared
5292 libraries, it must provide a <file>shlibs</file> file for other
5293 packages to use, and when a package is built which contains
5294 any shared libraries or compiled binaries, it must run
5295 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5296 on these to determine the libraries used and hence the
5297 dependencies needed by this package.<footnote>
5299 In the past, the shared libraries linked to were
5300 determined by calling <prgn>ldd</prgn>, but now
5301 <prgn>objdump</prgn> is used to do this. The only
5302 change this makes to package building is that
5303 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
5304 libraries, whereas in the past this was unnecessary.
5305 The rest of this footnote explains the advantage that
5310 We say that a binary <tt>foo</tt> <em>directly</em> uses
5311 a library <tt>libbar</tt> if it is explicitly linked
5312 with that library (that is, it uses the flag
5313 <tt>-lbar</tt> during the linking stage). Other
5314 libraries that are needed by <tt>libbar</tt> are linked
5315 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5316 linker will load them automatically when it loads
5317 <tt>libbar</tt>. A package should depend on
5318 the libraries it directly uses, and the dependencies for
5319 those libraries should automatically pull in the other
5324 Unfortunately, the <prgn>ldd</prgn> program shows both
5325 the directly and indirectly used libraries, meaning that
5326 the dependencies determined included both direct and
5327 indirect dependencies. The use of <prgn>objdump</prgn>
5328 avoids this problem by determining only the directly
5333 A good example of where this helps is the following. We
5334 could update <tt>libimlib</tt> with a new version that
5335 supports a new graphics format called dgf (but retaining
5336 the same major version number). If we used the old
5337 <prgn>ldd</prgn> method, every package that uses
5338 <tt>libimlib</tt> would need to be recompiled so it
5339 would also depend on <tt>libdgf</tt> or it wouldn't run
5340 due to missing symbols. However with the new system,
5341 packages using <tt>libimlib</tt> can rely on
5342 <tt>libimlib</tt> itself having the dependency on
5343 <tt>libdgf</tt> and so they would not need rebuilding.
5349 In the following sections, we will first describe where the
5350 various <tt>shlibs</tt> files are to be found, then how to
5351 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5352 file format and how to create them if your package contains a
5357 <heading>The <tt>shlibs</tt> files present on the system</heading>
5360 There are several places where <tt>shlibs</tt> files are
5361 found. The following list gives them in the order in which
5363 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5364 (The first one which gives the required information is used.)
5370 <p><file>debian/shlibs.local</file></p>
5373 This lists overrides for this package. Its use is
5374 described below (see <ref id="shlibslocal">).
5379 <p><file>/etc/dpkg/shlibs.override</file></p>
5382 This lists global overrides. This list is normally
5383 empty. It is maintained by the local system
5389 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5392 When packages are being built, any
5393 <file>debian/shlibs</file> files are copied into the
5394 control file area of the temporary build directory and
5395 given the name <file>shlibs</file>. These files give
5396 details of any shared libraries included in the
5398 An example may help here. Let us say that the
5399 source package <tt>foo</tt> generates two binary
5400 packages, <tt>libfoo2</tt> and
5401 <tt>foo-runtime</tt>. When building the binary
5402 packages, the two packages are created in the
5403 directories <file>debian/libfoo2</file> and
5404 <file>debian/foo-runtime</file> respectively.
5405 (<file>debian/tmp</file> could be used instead of one
5406 of these.) Since <tt>libfoo2</tt> provides the
5407 <tt>libfoo</tt> shared library, it will require a
5408 <tt>shlibs</tt> file, which will be installed in
5409 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
5411 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
5412 when <prgn>dpkg-shlibdeps</prgn> is run on the
5414 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
5416 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5417 determine whether <tt>foo-prog</tt>'s library
5418 dependencies are satisfied by any of the libraries
5419 provided by <tt>libfoo2</tt>. For this reason,
5420 <prgn>dpkg-shlibdeps</prgn> must only be run once
5421 all of the individual binary packages'
5422 <tt>shlibs</tt> files have been installed into the
5429 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5432 These are the <file>shlibs</file> files corresponding to
5433 all of the packages installed on the system, and are
5434 maintained by the relevant package maintainers.
5439 <p><file>/etc/dpkg/shlibs.default</file></p>
5442 This file lists any shared libraries whose packages
5443 have failed to provide correct <file>shlibs</file> files.
5444 It was used when the <file>shlibs</file> setup was first
5445 introduced, but it is now normally empty. It is
5446 maintained by the <tt>dpkg</tt> maintainer.
5454 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5455 <file>shlibs</file> files</heading>
5459 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5460 into your <file>debian/rules</file> file. If your package
5461 contains only compiled binaries and libraries (but no scripts),
5462 you can use a command such as:
5463 <example compact="compact">
5464 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5465 debian/tmp/usr/lib/*
5467 Otherwise, you will need to explicitly list the compiled
5468 binaries and libraries.<footnote>
5469 If you are using <tt>debhelper</tt>, the
5470 <prgn>dh_shlibdeps</prgn> program will do this work for
5471 you. It will also correctly handle multi-binary
5477 This command puts the dependency information into the
5478 <file>debian/substvars</file> file, which is then used by
5479 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5480 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5481 field in the control file for this to work.
5485 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
5486 done. If it does complain you might need to create your own
5487 <file>debian/shlibs.local</file> file, as explained below (see
5488 <ref id="shlibslocal">).
5492 If you have multiple binary packages, you will need to call
5493 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5494 compiled libraries or binaries. In such a case, you will
5495 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5496 utilities to specify a different <file>substvars</file> file.
5500 If you are creating a udeb for use in the Debian Installer,
5501 you will need to specify that <prgn>dpkg-shlibdeps</prgn>
5502 should use the dependency line of type <tt>udeb</tt> by
5503 adding the <tt>-tudeb</tt> option<footnote>
5504 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5505 will automatically add this option if it knows it is
5507 </footnote>. If there is no dependency line of type <tt>udeb</tt>
5508 in the <file>shlibs</file> file, <prgn>dpkg-shlibdeps</prgn> will
5509 fall back to the regular dependency line.
5513 For more details on dpkg-shlibdeps, please see
5514 <ref id="pkg-dpkg-shlibdeps"> and
5515 <manref name="dpkg-shlibdeps" section="1">.
5520 <heading>The <file>shlibs</file> File Format</heading>
5523 Each <file>shlibs</file> file has the same format. Lines
5524 beginning with <tt>#</tt> are considered to be comments and
5525 are ignored. Each line is of the form:
5526 <example compact="compact">
5527 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5532 We will explain this by reference to the example of the
5533 <tt>zlib1g</tt> package, which (at the time of writing)
5534 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5538 <var>type</var> is an optional element that indicates the type
5539 of package for which the line is valid. The only type currently
5540 in use is <tt>udeb</tt>. The colon and space after the type are
5545 <var>library-name</var> is the name of the shared library,
5546 in this case <tt>libz</tt>. (This must match the name part
5547 of the soname, see below.)
5551 <var>soname-version</var> is the version part of the soname of
5552 the library. The soname is the thing that must exactly match
5553 for the library to be recognized by the dynamic linker, and is
5555 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5556 example, <tt>libz.so.1</tt>.<footnote>
5557 This can be determined using the command
5558 <example compact="compact">
5559 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5562 The version part is the part which comes after
5563 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
5567 <var>dependencies</var> has the same syntax as a dependency
5568 field in a binary package control file. It should give
5569 details of which packages are required to satisfy a binary
5570 built against the version of the library contained in the
5571 package. See <ref id="depsyntax"> for details.
5575 In our example, if the first version of the <tt>zlib1g</tt>
5576 package which contained a minor number of at least
5577 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5578 <tt>shlibs</tt> entry for this library could say:
5579 <example compact="compact">
5580 libz 1 zlib1g (>= 1:1.1.3)
5582 The version-specific dependency is to avoid warnings from
5583 the dynamic linker about using older shared libraries with
5588 As zlib1g also provides a udeb containing the shared library,
5589 there would also be a second line:
5590 <example compact="compact">
5591 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5597 <heading>Providing a <file>shlibs</file> file</heading>
5600 If your package provides a shared library, you need to create
5601 a <file>shlibs</file> file following the format described above.
5602 It is usual to call this file <file>debian/shlibs</file> (but if
5603 you have multiple binary packages, you might want to call it
5604 <file>debian/shlibs.<var>package</var></file> instead). Then
5605 let <file>debian/rules</file> install it in the control area:
5606 <example compact="compact">
5607 install -m644 debian/shlibs debian/tmp/DEBIAN
5609 or, in the case of a multi-binary package:
5610 <example compact="compact">
5611 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5613 An alternative way of doing this is to create the
5614 <file>shlibs</file> file in the control area directly from
5615 <file>debian/rules</file> without using a <file>debian/shlibs</file>
5616 file at all,<footnote>
5617 This is what <prgn>dh_makeshlibs</prgn> in the
5618 <tt>debhelper</tt> suite does. If your package also has a udeb
5619 that provides a shared library, <prgn>dh_makeshlibs</prgn> can
5620 automatically generate the <tt>udeb:</tt> lines if you specify
5621 the name of the udeb with the <tt>--add-udeb</tt> option.
5623 since the <file>debian/shlibs</file> file itself is ignored by
5624 <prgn>dpkg-shlibdeps</prgn>.
5628 As <prgn>dpkg-shlibdeps</prgn> reads the
5629 <file>DEBIAN/shlibs</file> files in all of the binary packages
5630 being built from this source package, all of the
5631 <file>DEBIAN/shlibs</file> files should be installed before
5632 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5637 <sect1 id="shlibslocal">
5638 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
5641 This file is intended only as a <em>temporary</em> fix if
5642 your binaries or libraries depend on a library whose package
5643 does not yet provide a correct <file>shlibs</file> file.
5647 We will assume that you are trying to package a binary
5648 <tt>foo</tt>. When you try running
5649 <prgn>dpkg-shlibdeps</prgn> you get the following error
5650 message (<tt>-O</tt> displays the dependency information on
5651 <tt>stdout</tt> instead of writing it to
5652 <tt>debian/substvars</tt>, and the lines have been wrapped
5653 for ease of reading):
5654 <example compact="compact">
5655 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
5656 dpkg-shlibdeps: warning: unable to find dependency
5657 information for shared library libbar (soname 1,
5658 path /usr/lib/libbar.so.1, dependency field Depends)
5659 shlibs:Depends=libc6 (>= 2.2.2-2)
5661 You can then run <prgn>ldd</prgn> on the binary to find the
5662 full location of the library concerned:
5663 <example compact="compact">
5665 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5666 libc.so.6 => /lib/libc.so.6 (0x40032000)
5667 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5669 So the <prgn>foo</prgn> binary depends on the
5670 <prgn>libbar</prgn> shared library, but no package seems to
5671 provide a <file>*.shlibs</file> file handling
5672 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5673 determine the package responsible:
5674 <example compact="compact">
5675 $ dpkg -S /usr/lib/libbar.so.1
5676 bar1: /usr/lib/libbar.so.1
5677 $ dpkg -s bar1 | grep Version
5680 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5681 is the one we are using. Now we can file a bug against the
5682 <tt>bar1</tt> package and create our own
5683 <file>debian/shlibs.local</file> to locally fix the problem.
5684 Including the following line into your
5685 <file>debian/shlibs.local</file> file:
5686 <example compact="compact">
5687 libbar 1 bar1 (>= 1.0-1)
5689 should allow the package build to work.
5693 As soon as the maintainer of <tt>bar1</tt> provides a
5694 correct <file>shlibs</file> file, you should remove this line
5695 from your <file>debian/shlibs.local</file> file. (You should
5696 probably also then have a versioned <tt>Build-Depends</tt>
5697 on <tt>bar1</tt> to help ensure that others do not have the
5698 same problem building your package.)
5707 <chapt id="opersys"><heading>The Operating System</heading>
5710 <heading>File system hierarchy</heading>
5714 <heading>File System Structure</heading>
5717 The location of all installed files and directories must
5718 comply with the Filesystem Hierarchy Standard (FHS),
5719 version 2.3, with the exceptions noted below, and except
5720 where doing so would violate other terms of Debian
5721 Policy. The following exceptions to the FHS apply:
5726 The optional rules related to user specific
5727 configuration files for applications are stored in
5728 the user's home directory are relaxed. It is
5729 recommended that such files start with the
5730 '<tt>.</tt>' character (a "dot file"), and if an
5731 application needs to create more than one dot file
5732 then the preferred placement is in a subdirectory
5733 with a name starting with a '.' character, (a "dot
5734 directory"). In this case it is recommended the
5735 configuration files not start with the '.'
5741 The requirement for amd64 to use <file>/lib64</file>
5742 for 64 bit binaries is removed.
5747 The requirement for object files, internal binaries, and
5748 libraries, including <file>libc.so.*</file>, to be located
5749 directly under <file>/lib{,32}</file> and
5750 <file>/usr/lib{,32}</file> is amended, permitting files
5751 to instead be installed to
5752 <file>/lib/<var>triplet</var></file> and
5753 <file>/usr/lib/<var>triplet</var></file>, where
5754 <tt><var>triplet</var></tt> is the value returned by
5755 <tt>dpkg-architecture -qDEB_HOST_GNU_TYPE</tt> for the
5756 architecture of the package. Packages may <em>not</em>
5757 install files to any <var>triplet</var> path other
5758 than the one matching the architecture of that package;
5759 for instance, an <tt>Architecture: amd64</tt> package
5760 containing 32-bit x86 libraries may not install these
5761 libraries to <file>/usr/lib/i486-linux-gnu</file>.
5763 This is necessary in order to reserve the directories for
5764 use in cross-installation of library packages from other
5765 architectures, as part of the planned deployment of
5770 Applications may also use a single subdirectory under
5771 <file>/usr/lib/<var>triplet</var></file>.
5774 The execution time linker/loader, ld*, must still be made
5775 available in the existing location under /lib or /lib64
5776 since this is part of the ELF ABI for the architecture.
5781 The requirement that
5782 <file>/usr/local/share/man</file> be "synonymous"
5783 with <file>/usr/local/man</file> is relaxed to a
5788 The requirement that windowmanagers with a single
5789 configuration file call it <file>system.*wmrc</file>
5790 is removed, as is the restriction that the window
5791 manager subdirectory be named identically to the
5792 window manager name itself.
5797 The requirement that boot manager configuration
5798 files live in <file>/etc</file>, or at least are
5799 symlinked there, is relaxed to a recommendation.
5804 The following directories in the root filesystem are
5805 additionally allowed: <file>/sys</file> and
5806 <file>/selinux</file>. <footnote>These directories
5807 are used as mount points to mount virtual filesystems
5808 to get access to kernel information.</footnote>
5815 The version of this document referred here can be
5816 found in the <tt>debian-policy</tt> package or on <url
5817 id="http://www.debian.org/doc/packaging-manuals/fhs/"
5818 name="FHS (Debian copy)"> alongside this manual (or, if
5819 you have the <package>debian-policy</package> installed,
5821 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5822 (local copy)">). The
5823 latest version, which may be a more recent version, may
5825 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5826 Specific questions about following the standard may be
5827 asked on the <tt>debian-devel</tt> mailing list, or
5828 referred to the FHS mailing list (see the
5829 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5835 <heading>Site-specific programs</heading>
5838 As mandated by the FHS, packages must not place any
5839 files in <file>/usr/local</file>, either by putting them in
5840 the file system archive to be unpacked by <prgn>dpkg</prgn>
5841 or by manipulating them in their maintainer scripts.
5845 However, the package may create empty directories below
5846 <file>/usr/local</file> so that the system administrator knows
5847 where to place site-specific files. These are not
5848 directories <em>in</em> <file>/usr/local</file>, but are
5849 children of directories in <file>/usr/local</file>. These
5850 directories (<file>/usr/local/*/dir/</file>)
5851 should be removed on package removal if they are
5856 Note that this applies only to
5857 directories <em>below</em> <file>/usr/local</file>,
5858 not <em>in</em> <file>/usr/local</file>. Packages must
5859 not create sub-directories in the
5860 directory <file>/usr/local</file> itself, except those
5861 listed in FHS, section 4.5. However, you may create
5862 directories below them as you wish. You must not remove
5863 any of the directories listed in 4.5, even if you created
5868 Since <file>/usr/local</file> can be mounted read-only from a
5869 remote server, these directories must be created and
5870 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5871 maintainer scripts and not be included in the
5872 <file>.deb</file> archive. These scripts must not fail if
5873 either of these operations fail.
5877 For example, the <tt>emacsen-common</tt> package could
5878 contain something like
5879 <example compact="compact">
5880 if [ ! -e /usr/local/share/emacs ]
5882 if mkdir /usr/local/share/emacs 2>/dev/null
5884 chown root:staff /usr/local/share/emacs
5885 chmod 2775 /usr/local/share/emacs
5889 in its <prgn>postinst</prgn> script, and
5890 <example compact="compact">
5891 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5892 rmdir /usr/local/share/emacs 2>/dev/null || true
5894 in the <prgn>prerm</prgn> script. (Note that this form is
5895 used to ensure that if the script is interrupted, the
5896 directory <file>/usr/local/share/emacs</file> will still be
5901 If you do create a directory in <file>/usr/local</file> for
5902 local additions to a package, you should ensure that
5903 settings in <file>/usr/local</file> take precedence over the
5904 equivalents in <file>/usr</file>.
5908 However, because <file>/usr/local</file> and its contents are
5909 for exclusive use of the local administrator, a package
5910 must not rely on the presence or absence of files or
5911 directories in <file>/usr/local</file> for normal operation.
5915 The <file>/usr/local</file> directory itself and all the
5916 subdirectories created by the package should (by default) have
5917 permissions 2775 (group-writable and set-group-id) and be
5918 owned by <tt>root:staff</tt>.
5923 <heading>The system-wide mail directory</heading>
5925 The system-wide mail directory
5926 is <file>/var/mail</file>. This directory is part of the
5927 base system and should not be owned by any particular mail
5928 agents. The use of the old
5929 location <file>/var/spool/mail</file> is deprecated, even
5930 though the spool may still be physically located there.
5936 <heading>Users and groups</heading>
5939 <heading>Introduction</heading>
5941 The Debian system can be configured to use either plain or
5946 Some user ids (UIDs) and group ids (GIDs) are reserved
5947 globally for use by certain packages. Because some
5948 packages need to include files which are owned by these
5949 users or groups, or need the ids compiled into binaries,
5950 these ids must be used on any Debian system only for the
5951 purpose for which they are allocated. This is a serious
5952 restriction, and we should avoid getting in the way of
5953 local administration policies. In particular, many sites
5954 allocate users and/or local system groups starting at 100.
5958 Apart from this we should have dynamically allocated ids,
5959 which should by default be arranged in some sensible
5960 order, but the behavior should be configurable.
5964 Packages other than <tt>base-passwd</tt> must not modify
5965 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5966 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5971 <heading>UID and GID classes</heading>
5973 The UID and GID numbers are divided into classes as
5979 Globally allocated by the Debian project, the same
5980 on every Debian system. These ids will appear in
5981 the <file>passwd</file> and <file>group</file> files of all
5982 Debian systems, new ids in this range being added
5983 automatically as the <tt>base-passwd</tt> package is
5988 Packages which need a single statically allocated
5989 uid or gid should use one of these; their
5990 maintainers should ask the <tt>base-passwd</tt>
5998 Dynamically allocated system users and groups.
5999 Packages which need a user or group, but can have
6000 this user or group allocated dynamically and
6001 differently on each system, should use <tt>adduser
6002 --system</tt> to create the group and/or user.
6003 <prgn>adduser</prgn> will check for the existence of
6004 the user or group, and if necessary choose an unused
6005 id based on the ranges specified in
6006 <file>adduser.conf</file>.
6010 <tag>1000-59999:</tag>
6013 Dynamically allocated user accounts. By default
6014 <prgn>adduser</prgn> will choose UIDs and GIDs for
6015 user accounts in this range, though
6016 <file>adduser.conf</file> may be used to modify this
6021 <tag>60000-64999:</tag>
6024 Globally allocated by the Debian project, but only
6025 created on demand. The ids are allocated centrally
6026 and statically, but the actual accounts are only
6027 created on users' systems on demand.
6031 These ids are for packages which are obscure or
6032 which require many statically-allocated ids. These
6033 packages should check for and create the accounts in
6034 <file>/etc/passwd</file> or <file>/etc/group</file> (using
6035 <prgn>adduser</prgn> if it has this facility) if
6036 necessary. Packages which are likely to require
6037 further allocations should have a "hole" left after
6038 them in the allocation, to give them room to
6043 <tag>65000-65533:</tag>
6051 User <tt>nobody</tt>. The corresponding gid refers
6052 to the group <tt>nogroup</tt>.
6059 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
6060 not</em> be used, because it is the error return
6069 <sect id="sysvinit">
6070 <heading>System run levels and <file>init.d</file> scripts</heading>
6072 <sect1 id="/etc/init.d">
6073 <heading>Introduction</heading>
6076 The <file>/etc/init.d</file> directory contains the scripts
6077 executed by <prgn>init</prgn> at boot time and when the
6078 init state (or "runlevel") is changed (see <manref
6079 name="init" section="8">).
6083 There are at least two different, yet functionally
6084 equivalent, ways of handling these scripts. For the sake
6085 of simplicity, this document describes only the symbolic
6086 link method. However, it must not be assumed by maintainer
6087 scripts that this method is being used, and any automated
6088 manipulation of the various runlevel behaviors by
6089 maintainer scripts must be performed using
6090 <prgn>update-rc.d</prgn> as described below and not by
6091 manually installing or removing symlinks. For information
6092 on the implementation details of the other method,
6093 implemented in the <tt>file-rc</tt> package, please refer
6094 to the documentation of that package.
6098 These scripts are referenced by symbolic links in the
6099 <file>/etc/rc<var>n</var>.d</file> directories. When changing
6100 runlevels, <prgn>init</prgn> looks in the directory
6101 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
6102 execute, where <tt><var>n</var></tt> is the runlevel that
6103 is being changed to, or <tt>S</tt> for the boot-up
6108 The names of the links all have the form
6109 <file>S<var>mm</var><var>script</var></file> or
6110 <file>K<var>mm</var><var>script</var></file> where
6111 <var>mm</var> is a two-digit number and <var>script</var>
6112 is the name of the script (this should be the same as the
6113 name of the actual script in <file>/etc/init.d</file>).
6117 When <prgn>init</prgn> changes runlevel first the targets
6118 of the links whose names start with a <tt>K</tt> are
6119 executed, each with the single argument <tt>stop</tt>,
6120 followed by the scripts prefixed with an <tt>S</tt>, each
6121 with the single argument <tt>start</tt>. (The links are
6122 those in the <file>/etc/rc<var>n</var>.d</file> directory
6123 corresponding to the new runlevel.) The <tt>K</tt> links
6124 are responsible for killing services and the <tt>S</tt>
6125 link for starting services upon entering the runlevel.
6129 For example, if we are changing from runlevel 2 to
6130 runlevel 3, init will first execute all of the <tt>K</tt>
6131 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
6132 all of the <tt>S</tt> prefixed scripts in that directory.
6133 The links starting with <tt>K</tt> will cause the
6134 referred-to file to be executed with an argument of
6135 <tt>stop</tt>, and the <tt>S</tt> links with an argument
6140 The two-digit number <var>mm</var> is used to determine
6141 the order in which to run the scripts: low-numbered links
6142 have their scripts run first. For example, the
6143 <tt>K20</tt> scripts will be executed before the
6144 <tt>K30</tt> scripts. This is used when a certain service
6145 must be started before another. For example, the name
6146 server <prgn>bind</prgn> might need to be started before
6147 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
6148 can set up its access lists. In this case, the script
6149 that starts <prgn>bind</prgn> would have a lower number
6150 than the script that starts <prgn>inn</prgn> so that it
6152 <example compact="compact">
6159 The two runlevels 0 (halt) and 6 (reboot) are slightly
6160 different. In these runlevels, the links with an
6161 <tt>S</tt> prefix are still called after those with a
6162 <tt>K</tt> prefix, but they too are called with the single
6163 argument <tt>stop</tt>.
6167 <sect1 id="writing-init">
6168 <heading>Writing the scripts</heading>
6171 Packages that include daemons for system services should
6172 place scripts in <file>/etc/init.d</file> to start or stop
6173 services at boot time or during a change of runlevel.
6174 These scripts should be named
6175 <file>/etc/init.d/<var>package</var></file>, and they should
6176 accept one argument, saying what to do:
6179 <tag><tt>start</tt></tag>
6180 <item>start the service,</item>
6182 <tag><tt>stop</tt></tag>
6183 <item>stop the service,</item>
6185 <tag><tt>restart</tt></tag>
6186 <item>stop and restart the service if it's already running,
6187 otherwise start the service</item>
6189 <tag><tt>reload</tt></tag>
6190 <item><p>cause the configuration of the service to be
6191 reloaded without actually stopping and restarting
6194 <tag><tt>force-reload</tt></tag>
6195 <item>cause the configuration to be reloaded if the
6196 service supports this, otherwise restart the
6200 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
6201 <tt>force-reload</tt> options should be supported by all
6202 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
6207 The <file>init.d</file> scripts must ensure that they will
6208 behave sensibly (i.e., returning success and not starting
6209 multiple copies of a service) if invoked with <tt>start</tt>
6210 when the service is already running, or with <tt>stop</tt>
6211 when it isn't, and that they don't kill unfortunately-named
6212 user processes. The best way to achieve this is usually to
6213 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
6218 Be careful of using <tt>set -e</tt> in <file>init.d</file>
6219 scripts. Writing correct <file>init.d</file> scripts requires
6220 accepting various error exit statuses when daemons are already
6221 running or already stopped without aborting
6222 the <file>init.d</file> script, and common <file>init.d</file>
6223 function libraries are not safe to call with <tt>set -e</tt>
6225 <tt>/lib/lsb/init-functions</tt>, which assists in writing
6226 LSB-compliant init scripts, may fail if <tt>set -e</tt> is
6227 in effect and echoing status messages to the console fails,
6229 </footnote>. For <tt>init.d</tt> scripts, it's often easier
6230 to not use <tt>set -e</tt> and instead check the result of
6231 each command separately.
6235 If a service reloads its configuration automatically (as
6236 in the case of <prgn>cron</prgn>, for example), the
6237 <tt>reload</tt> option of the <file>init.d</file> script
6238 should behave as if the configuration has been reloaded
6243 The <file>/etc/init.d</file> scripts must be treated as
6244 configuration files, either (if they are present in the
6245 package, that is, in the .deb file) by marking them as
6246 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
6247 by managing them correctly in the maintainer scripts (see
6248 <ref id="config-files">). This is important since we want
6249 to give the local system administrator the chance to adapt
6250 the scripts to the local system, e.g., to disable a
6251 service without de-installing the package, or to specify
6252 some special command line options when starting a service,
6253 while making sure their changes aren't lost during the next
6258 These scripts should not fail obscurely when the
6259 configuration files remain but the package has been
6260 removed, as configuration files remain on the system after
6261 the package has been removed. Only when <prgn>dpkg</prgn>
6262 is executed with the <tt>--purge</tt> option will
6263 configuration files be removed. In particular, as the
6264 <file>/etc/init.d/<var>package</var></file> script itself is
6265 usually a <tt>conffile</tt>, it will remain on the system
6266 if the package is removed but not purged. Therefore, you
6267 should include a <tt>test</tt> statement at the top of the
6269 <example compact="compact">
6270 test -f <var>program-executed-later-in-script</var> || exit 0
6275 Often there are some variables in the <file>init.d</file>
6276 scripts whose values control the behavior of the scripts,
6277 and which a system administrator is likely to want to
6278 change. As the scripts themselves are frequently
6279 <tt>conffile</tt>s, modifying them requires that the
6280 administrator merge in their changes each time the package
6281 is upgraded and the <tt>conffile</tt> changes. To ease
6282 the burden on the system administrator, such configurable
6283 values should not be placed directly in the script.
6284 Instead, they should be placed in a file in
6285 <file>/etc/default</file>, which typically will have the same
6286 base name as the <file>init.d</file> script. This extra file
6287 should be sourced by the script when the script runs. It
6288 must contain only variable settings and comments in SUSv3
6289 <prgn>sh</prgn> format. It may either be a
6290 <tt>conffile</tt> or a configuration file maintained by
6291 the package maintainer scripts. See <ref id="config-files">
6296 To ensure that vital configurable values are always
6297 available, the <file>init.d</file> script should set default
6298 values for each of the shell variables it uses, either
6299 before sourcing the <file>/etc/default/</file> file or
6300 afterwards using something like the <tt>:
6301 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6302 script must behave sensibly and not fail if the
6303 <file>/etc/default</file> file is deleted.
6307 <file>/var/run</file> and <file>/var/lock</file> may be mounted
6308 as temporary filesystems<footnote>
6309 For example, using the <tt>RAMRUN</tt> and <tt>RAMLOCK</tt>
6310 options in <file>/etc/default/rcS</file>.
6311 </footnote>, so the <file>init.d</file> scripts must handle this
6312 correctly. This will typically amount to creating any required
6313 subdirectories dynamically when the <file>init.d</file> script
6314 is run, rather than including them in the package and relying on
6315 <prgn>dpkg</prgn> to create them.
6320 <heading>Interfacing with the initscript system</heading>
6323 Maintainers should use the abstraction layer provided by
6324 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6325 programs to deal with initscripts in their packages'
6326 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6327 and <prgn>postrm</prgn>.
6331 Directly managing the /etc/rc?.d links and directly
6332 invoking the <file>/etc/init.d/</file> initscripts should
6333 be done only by packages providing the initscript
6334 subsystem (such as <prgn>sysv-rc</prgn> and
6335 <prgn>file-rc</prgn>).
6339 <heading>Managing the links</heading>
6342 The program <prgn>update-rc.d</prgn> is provided for
6343 package maintainers to arrange for the proper creation and
6344 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6345 or their functional equivalent if another method is being
6346 used. This may be used by maintainers in their packages'
6347 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6351 You must not include any <file>/etc/rc<var>n</var>.d</file>
6352 symbolic links in the actual archive or manually create or
6353 remove the symbolic links in maintainer scripts; you must
6354 use the <prgn>update-rc.d</prgn> program instead. (The
6355 former will fail if an alternative method of maintaining
6356 runlevel information is being used.) You must not include
6357 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6358 in the archive either. (Only the <tt>sysvinit</tt>
6363 By default <prgn>update-rc.d</prgn> will start services in
6364 each of the multi-user state runlevels (2, 3, 4, and 5)
6365 and stop them in the halt runlevel (0), the single-user
6366 runlevel (1) and the reboot runlevel (6). The system
6367 administrator will have the opportunity to customize
6368 runlevels by simply adding, moving, or removing the
6369 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6370 symbolic links are being used, or by modifying
6371 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6376 To get the default behavior for your package, put in your
6377 <prgn>postinst</prgn> script
6378 <example compact="compact">
6379 update-rc.d <var>package</var> defaults
6381 and in your <prgn>postrm</prgn>
6382 <example compact="compact">
6383 if [ "$1" = purge ]; then
6384 update-rc.d <var>package</var> remove
6386 </example>. Note that if your package changes runlevels
6387 or priority, you may have to remove and recreate the links,
6388 since otherwise the old links may persist. Refer to the
6389 documentation of <prgn>update-rc.d</prgn>.
6393 This will use a default sequence number of 20. If it does
6394 not matter when or in which order the <file>init.d</file>
6395 script is run, use this default. If it does, then you
6396 should talk to the maintainer of the <prgn>sysvinit</prgn>
6397 package or post to <tt>debian-devel</tt>, and they will
6398 help you choose a number.
6402 For more information about using <tt>update-rc.d</tt>,
6403 please consult its man page <manref name="update-rc.d"
6409 <heading>Running initscripts</heading>
6411 The program <prgn>invoke-rc.d</prgn> is provided to make
6412 it easier for package maintainers to properly invoke an
6413 initscript, obeying runlevel and other locally-defined
6414 constraints that might limit a package's right to start,
6415 stop and otherwise manage services. This program may be
6416 used by maintainers in their packages' scripts.
6420 The package maintainer scripts must use
6421 <prgn>invoke-rc.d</prgn> to invoke the
6422 <file>/etc/init.d/*</file> initscripts, instead of
6423 calling them directly.
6427 By default, <prgn>invoke-rc.d</prgn> will pass any
6428 action requests (start, stop, reload, restart...) to the
6429 <file>/etc/init.d</file> script, filtering out requests
6430 to start or restart a service out of its intended
6435 Most packages will simply need to change:
6436 <example compact="compact">/etc/init.d/<package>
6437 <action></example> in their <prgn>postinst</prgn>
6438 and <prgn>prerm</prgn> scripts to:
6439 <example compact="compact">
6440 if which invoke-rc.d >/dev/null 2>&1; then
6441 invoke-rc.d <var>package</var> <action>
6443 /etc/init.d/<var>package</var> <action>
6449 A package should register its initscript services using
6450 <prgn>update-rc.d</prgn> before it tries to invoke them
6451 using <prgn>invoke-rc.d</prgn>. Invocation of
6452 unregistered services may fail.
6456 For more information about using
6457 <prgn>invoke-rc.d</prgn>, please consult its man page
6458 <manref name="invoke-rc.d" section="8">.
6464 <heading>Boot-time initialization</heading>
6467 There used to be another directory, <file>/etc/rc.boot</file>,
6468 which contained scripts which were run once per machine
6469 boot. This has been deprecated in favour of links from
6470 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6471 described in <ref id="/etc/init.d">. Packages must not
6472 place files in <file>/etc/rc.boot</file>.
6477 <heading>Example</heading>
6480 An example on which you can base your
6481 <file>/etc/init.d</file> scripts is found in
6482 <file>/etc/init.d/skeleton</file>.
6489 <heading>Console messages from <file>init.d</file> scripts</heading>
6492 This section describes the formats to be used for messages
6493 written to standard output by the <file>/etc/init.d</file>
6494 scripts. The intent is to improve the consistency of
6495 Debian's startup and shutdown look and feel. For this
6496 reason, please look very carefully at the details. We want
6497 the messages to have the same format in terms of wording,
6498 spaces, punctuation and case of letters.
6502 Here is a list of overall rules that should be used for
6503 messages generated by <file>/etc/init.d</file> scripts.
6509 The message should fit in one line (fewer than 80
6510 characters), start with a capital letter and end with
6511 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6515 If the script is performing some time consuming task in
6516 the background (not merely starting or stopping a
6517 program, for instance), an ellipsis (three dots:
6518 <tt>...</tt>) should be output to the screen, with no
6519 leading or tailing whitespace or line feeds.
6523 The messages should appear as if the computer is telling
6524 the user what it is doing (politely :-), but should not
6525 mention "it" directly. For example, instead of:
6526 <example compact="compact">
6527 I'm starting network daemons: nfsd mountd.
6529 the message should say
6530 <example compact="compact">
6531 Starting network daemons: nfsd mountd.
6538 <tt>init.d</tt> script should use the following standard
6539 message formats for the situations enumerated below.
6545 <p>When daemons are started</p>
6548 If the script starts one or more daemons, the output
6549 should look like this (a single line, no leading
6551 <example compact="compact">
6552 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6554 The <var>description</var> should describe the
6555 subsystem the daemon or set of daemons are part of,
6556 while <var>daemon-1</var> up to <var>daemon-n</var>
6557 denote each daemon's name (typically the file name of
6562 For example, the output of <file>/etc/init.d/lpd</file>
6564 <example compact="compact">
6565 Starting printer spooler: lpd.
6570 This can be achieved by saying
6571 <example compact="compact">
6572 echo -n "Starting printer spooler: lpd"
6573 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6576 in the script. If there are more than one daemon to
6577 start, the output should look like this:
6578 <example compact="compact">
6579 echo -n "Starting remote file system services:"
6580 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6581 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6582 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6585 This makes it possible for the user to see what is
6586 happening and when the final daemon has been started.
6587 Care should be taken in the placement of white spaces:
6588 in the example above the system administrators can
6589 easily comment out a line if they don't want to start
6590 a specific daemon, while the displayed message still
6596 <p>When a system parameter is being set</p>
6599 If you have to set up different system parameters
6600 during the system boot, you should use this format:
6601 <example compact="compact">
6602 Setting <var>parameter</var> to "<var>value</var>".
6607 You can use a statement such as the following to get
6609 <example compact="compact">
6610 echo "Setting DNS domainname to \"$domainname\"."
6615 Note that the same symbol (<tt>"</tt>) <!-- " --> is used
6616 for the left and right quotation marks. A grave accent
6617 (<tt>`</tt>) is not a quote character; neither is an
6618 apostrophe (<tt>'</tt>).
6623 <p>When a daemon is stopped or restarted</p>
6626 When you stop or restart a daemon, you should issue a
6627 message identical to the startup message, except that
6628 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6629 or <tt>Restarting</tt> respectively.
6633 For example, stopping the printer daemon will look like
6635 <example compact="compact">
6636 Stopping printer spooler: lpd.
6642 <p>When something is executed</p>
6645 There are several examples where you have to run a
6646 program at system startup or shutdown to perform a
6647 specific task, for example, setting the system's clock
6648 using <prgn>netdate</prgn> or killing all processes
6649 when the system shuts down. Your message should look
6651 <example compact="compact">
6652 Doing something very useful...done.
6654 You should print the <tt>done.</tt> immediately after
6655 the job has been completed, so that the user is
6656 informed why they have to wait. You can get this
6658 <example compact="compact">
6659 echo -n "Doing something very useful..."
6668 <p>When the configuration is reloaded</p>
6671 When a daemon is forced to reload its configuration
6672 files you should use the following format:
6673 <example compact="compact">
6674 Reloading <var>description</var> configuration...done.
6676 where <var>description</var> is the same as in the
6677 daemon starting message.
6685 <heading>Cron jobs</heading>
6688 Packages must not modify the configuration file
6689 <file>/etc/crontab</file>, and they must not modify the files in
6690 <file>/var/spool/cron/crontabs</file>.</p>
6693 If a package wants to install a job that has to be executed
6694 via cron, it should place a file with the name of the
6695 package in one or more of the following directories:
6696 <example compact="compact">
6702 As these directory names imply, the files within them are
6703 executed on an hourly, daily, weekly, or monthly basis,
6704 respectively. The exact times are listed in
6705 <file>/etc/crontab</file>.</p>
6708 All files installed in any of these directories must be
6709 scripts (e.g., shell scripts or Perl scripts) so that they
6710 can easily be modified by the local system administrator.
6711 In addition, they must be treated as configuration files.
6715 If a certain job has to be executed at some other frequency or
6716 at a specific time, the package should install a file
6717 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6718 same syntax as <file>/etc/crontab</file> and is processed by
6719 <prgn>cron</prgn> automatically. The file must also be
6720 treated as a configuration file. (Note that entries in the
6721 <file>/etc/cron.d</file> directory are not handled by
6722 <prgn>anacron</prgn>. Thus, you should only use this
6723 directory for jobs which may be skipped if the system is not
6726 Unlike <file>crontab</file> files described in the IEEE Std
6727 1003.1-2008 (POSIX.1) available from
6728 <url id="http://www.opengroup.org/onlinepubs/9699919799/"
6729 name="The Open Group">, the files in
6730 <file>/etc/cron.d</file> and the file
6731 <file>/etc/crontab</file> have seven fields; namely:
6733 <item>Minute [0,59]</item>
6734 <item>Hour [0,23]</item>
6735 <item>Day of the month [1,31]</item>
6736 <item>Month of the year [1,12]</item>
6737 <item>Day of the week ([0,6] with 0=Sunday)</item>
6738 <item>Username</item>
6739 <item>Command to be run</item>
6741 Ranges of numbers are allowed. Ranges are two numbers
6742 separated with a hyphen. The specified range is inclusive.
6743 Lists are allowed. A list is a set of numbers (or ranges)
6744 separated by commas. Step values can be used in conjunction
6749 The scripts or <tt>crontab</tt> entries in these directories should
6750 check if all necessary programs are installed before they
6751 try to execute them. Otherwise, problems will arise when a
6752 package was removed but not purged since configuration files
6753 are kept on the system in this situation.
6757 Any <tt>cron</tt> daemon must provide
6758 <file>/usr/bin/crontab</file> and support normal
6759 <tt>crontab</tt> entries as specified in POSIX. The daemon
6760 must also support names for days and months, ranges, and
6761 step values. It has to support <file>/etc/crontab</file>,
6762 and correctly execute the scripts in
6763 <file>/etc/cron.d</file>. The daemon must also correctly
6765 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>.
6770 <heading>Menus</heading>
6773 The Debian <tt>menu</tt> package provides a standard
6774 interface between packages providing applications and
6775 <em>menu programs</em> (either X window managers or
6776 text-based menu programs such as <prgn>pdmenu</prgn>).
6780 All packages that provide applications that need not be
6781 passed any special command line arguments for normal
6782 operation should register a menu entry for those
6783 applications, so that users of the <tt>menu</tt> package
6784 will automatically get menu entries in their window
6785 managers, as well in shells like <tt>pdmenu</tt>.
6789 Menu entries should follow the current menu policy.
6793 The menu policy can be found in the <tt>menu-policy</tt>
6794 files in the <tt>debian-policy</tt> package.
6795 It is also available from the Debian web mirrors at
6796 <tt><url name="/doc/packaging-manuals/menu-policy/"
6797 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6801 Please also refer to the <em>Debian Menu System</em>
6802 documentation that comes with the <package>menu</package>
6803 package for information about how to register your
6809 <heading>Multimedia handlers</heading>
6812 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6813 is a mechanism for encoding files and data streams and
6814 providing meta-information about them, in particular their
6815 type (e.g. audio or video) and format (e.g. PNG, HTML,
6820 Registration of MIME type handlers allows programs like mail
6821 user agents and web browsers to invoke these handlers to
6822 view, edit or display MIME types they don't support directly.
6826 Packages which provide the ability to view/show/play,
6827 compose, edit or print MIME types should register themselves
6828 as such following the current MIME support policy.
6832 The MIME support policy can be found in the <tt>mime-policy</tt>
6833 files in the <tt>debian-policy</tt> package.
6834 It is also available from the Debian web mirrors at
6835 <tt><url name="/doc/packaging-manuals/mime-policy/"
6836 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6842 <heading>Keyboard configuration</heading>
6845 To achieve a consistent keyboard configuration so that all
6846 applications interpret a keyboard event the same way, all
6847 programs in the Debian distribution must be configured to
6848 comply with the following guidelines.
6852 The following keys must have the specified interpretations:
6855 <tag><tt><--</tt></tag>
6856 <item>delete the character to the left of the cursor</item>
6858 <tag><tt>Delete</tt></tag>
6859 <item>delete the character to the right of the cursor</item>
6861 <tag><tt>Control+H</tt></tag>
6862 <item>emacs: the help prefix</item>
6865 The interpretation of any keyboard events should be
6866 independent of the terminal that is used, be it a virtual
6867 console, an X terminal emulator, an rlogin/telnet session,
6872 The following list explains how the different programs
6873 should be set up to achieve this:
6879 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6883 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6887 X translations are set up to make
6888 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6889 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6890 is the vt220 escape code for the "delete character"
6891 key). This must be done by loading the X resources
6892 using <prgn>xrdb</prgn> on all local X displays, not
6893 using the application defaults, so that the
6894 translation resources used correspond to the
6895 <prgn>xmodmap</prgn> settings.
6899 The Linux console is configured to make
6900 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6901 generate <tt>ESC [ 3 ~</tt>.
6905 X applications are configured so that <tt><</tt>
6906 deletes left, and <tt>Delete</tt> deletes right. Motif
6907 applications already work like this.
6911 Terminals should have <tt>stty erase ^?</tt> .
6915 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6916 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6917 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6921 Emacs is programmed to map <tt>KB_Backspace</tt> or
6922 the <tt>stty erase</tt> character to
6923 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6924 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6925 <tt>^H</tt> to <tt>help</tt> as always.
6929 Other applications use the <tt>stty erase</tt>
6930 character and <tt>kdch1</tt> for the two delete keys,
6931 with ASCII DEL being "delete previous character" and
6932 <tt>kdch1</tt> being "delete character under
6940 This will solve the problem except for the following
6947 Some terminals have a <tt><--</tt> key that cannot
6948 be made to produce anything except <tt>^H</tt>. On
6949 these terminals Emacs help will be unavailable on
6950 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6951 character takes precedence in Emacs, and has been set
6952 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6953 available) can be used instead.
6957 Some operating systems use <tt>^H</tt> for <tt>stty
6958 erase</tt>. However, modern telnet versions and all
6959 rlogin versions propagate <tt>stty</tt> settings, and
6960 almost all UNIX versions honour <tt>stty erase</tt>.
6961 Where the <tt>stty</tt> settings are not propagated
6962 correctly, things can be made to work by using
6963 <tt>stty</tt> manually.
6967 Some systems (including previous Debian versions) use
6968 <prgn>xmodmap</prgn> to arrange for both
6969 <tt><--</tt> and <tt>Delete</tt> to generate
6970 <tt>KB_Delete</tt>. We can change the behavior of
6971 their X clients using the same X resources that we use
6972 to do it for our own clients, or configure our clients
6973 using their resources when things are the other way
6974 around. On displays configured like this
6975 <tt>Delete</tt> will not work, but <tt><--</tt>
6980 Some operating systems have different <tt>kdch1</tt>
6981 settings in their <tt>terminfo</tt> database for
6982 <tt>xterm</tt> and others. On these systems the
6983 <tt>Delete</tt> key will not work correctly when you
6984 log in from a system conforming to our policy, but
6985 <tt><--</tt> will.
6992 <heading>Environment variables</heading>
6995 A program must not depend on environment variables to get
6996 reasonable defaults. (That's because these environment
6997 variables would have to be set in a system-wide
6998 configuration file like <file>/etc/profile</file>, which is not
6999 supported by all shells.)
7003 If a program usually depends on environment variables for its
7004 configuration, the program should be changed to fall back to
7005 a reasonable default configuration if these environment
7006 variables are not present. If this cannot be done easily
7007 (e.g., if the source code of a non-free program is not
7008 available), the program must be replaced by a small
7009 "wrapper" shell script which sets the environment variables
7010 if they are not already defined, and calls the original program.
7014 Here is an example of a wrapper script for this purpose:
7016 <example compact="compact">
7018 BAR=${BAR:-/var/lib/fubar}
7020 exec /usr/lib/foo/foo "$@"
7025 Furthermore, as <file>/etc/profile</file> is a configuration
7026 file of the <prgn>base-files</prgn> package, other packages must
7027 not put any environment variables or other commands into that
7032 <sect id="doc-base">
7033 <heading>Registering Documents using doc-base</heading>
7036 The <package>doc-base</package> package implements a
7037 flexible mechanism for handling and presenting
7038 documentation. The recommended practice is for every Debian
7039 package that provides online documentation (other than just
7040 manual pages) to register these documents with
7041 <package>doc-base</package> by installing a
7042 <package>doc-base</package> control file via the
7043 <prgn/install-docs/ script at installation time and
7044 de-register the manuals again when the package is removed.
7047 Please refer to the documentation that comes with the
7048 <package>doc-base</package> package for information and
7057 <heading>Files</heading>
7060 <heading>Binaries</heading>
7063 Two different packages must not install programs with
7064 different functionality but with the same filenames. (The
7065 case of two programs having the same functionality but
7066 different implementations is handled via "alternatives" or
7067 the "Conflicts" mechanism. See <ref id="maintscripts"> and
7068 <ref id="conflicts"> respectively.) If this case happens,
7069 one of the programs must be renamed. The maintainers should
7070 report this to the <tt>debian-devel</tt> mailing list and
7071 try to find a consensus about which program will have to be
7072 renamed. If a consensus cannot be reached, <em>both</em>
7073 programs must be renamed.
7077 By default, when a package is being built, any binaries
7078 created should include debugging information, as well as
7079 being compiled with optimization. You should also turn on
7080 as many reasonable compilation warnings as possible; this
7081 makes life easier for porters, who can then look at build
7082 logs for possible problems. For the C programming language,
7083 this means the following compilation parameters should be
7085 <example compact="compact">
7087 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
7089 INSTALL = install -s # (or use strip on the files in debian/tmp)
7094 Note that by default all installed binaries should be stripped,
7095 either by using the <tt>-s</tt> flag to
7096 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
7097 the binaries after they have been copied into
7098 <file>debian/tmp</file> but before the tree is made into a
7103 Although binaries in the build tree should be compiled with
7104 debugging information by default, it can often be difficult to
7105 debug programs if they are also subjected to compiler
7106 optimization. For this reason, it is recommended to support the
7107 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
7108 (see <ref id="debianrules-options">). This variable can contain
7109 several flags to change how a package is compiled and built.
7113 It is up to the package maintainer to decide what
7114 compilation options are best for the package. Certain
7115 binaries (such as computationally-intensive programs) will
7116 function better with certain flags (<tt>-O3</tt>, for
7117 example); feel free to use them. Please use good judgment
7118 here. Don't use flags for the sake of it; only use them
7119 if there is good reason to do so. Feel free to override
7120 the upstream author's ideas about which compilation
7121 options are best: they are often inappropriate for our
7127 <sect id="libraries">
7128 <heading>Libraries</heading>
7131 If the package is <strong>architecture: any</strong>, then
7132 the shared library compilation and linking flags must have
7133 <tt>-fPIC</tt>, or the package shall not build on some of
7134 the supported architectures<footnote>
7136 If you are using GCC, <tt>-fPIC</tt> produces code with
7137 relocatable position independent code, which is required for
7138 most architectures to create a shared library, with i386 and
7139 perhaps some others where non position independent code is
7140 permitted in a shared library.
7143 Position independent code may have a performance penalty,
7144 especially on <tt>i386</tt>. However, in most cases the
7145 speed penalty must be measured against the memory wasted on
7146 the few architectures where non position independent code is
7149 </footnote>. Any exception to this rule must be discussed on
7150 the mailing list <em>debian-devel@lists.debian.org</em>, and
7151 a rough consensus obtained. The reasons for not compiling
7152 with <tt>-fPIC</tt> flag must be recorded in the file
7153 <tt>README.Debian</tt>, and care must be taken to either
7154 restrict the architecture or arrange for <tt>-fPIC</tt> to
7155 be used on architectures where it is required.<footnote>
7157 Some of the reasons why this might be required is if the
7158 library contains hand crafted assembly code that is not
7159 relocatable, the speed penalty is excessive for compute
7160 intensive libs, and similar reasons.
7165 As to the static libraries, the common case is not to have
7166 relocatable code, since there is no benefit, unless in specific
7167 cases; therefore the static version must not be compiled
7168 with the <tt>-fPIC</tt> flag. Any exception to this rule
7169 should be discussed on the mailing list
7170 <em>debian-devel@lists.debian.org</em>, and the reasons for
7171 compiling with the <tt>-fPIC</tt> flag must be recorded in
7172 the file <tt>README.Debian</tt>. <footnote>
7174 Some of the reasons for linking static libraries with
7175 the <tt>-fPIC</tt> flag are if, for example, one needs a
7176 Perl API for a library that is under rapid development,
7177 and has an unstable API, so shared libraries are
7178 pointless at this phase of the library's development. In
7179 that case, since Perl needs a library with relocatable
7180 code, it may make sense to create a static library with
7181 relocatable code. Another reason cited is if you are
7182 distilling various libraries into a common shared
7183 library, like <tt>mklibs</tt> does in the Debian
7189 In other words, if both a shared and a static library is
7190 being built, each source unit (<tt>*.c</tt>, for example,
7191 for C files) will need to be compiled twice, for the normal
7195 You must specify the gcc option <tt>-D_REENTRANT</tt>
7196 when building a library (either static or shared) to make
7197 the library compatible with LinuxThreads.
7201 Although not enforced by the build tools, shared libraries
7202 must be linked against all libraries that they use symbols from
7203 in the same way that binaries are. This ensures the correct
7204 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
7205 system and guarantees that all libraries can be safely opened
7206 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
7207 option <tt>-Wl,-z,defs</tt> when building a shared library.
7208 Since this option enforces symbol resolution at build time,
7209 a missing library reference will be caught early as a fatal
7214 All installed shared libraries should be stripped with
7215 <example compact="compact">
7216 strip --strip-unneeded <var>your-lib</var>
7218 (The option <tt>--strip-unneeded</tt> makes
7219 <prgn>strip</prgn> remove only the symbols which aren't
7220 needed for relocation processing.) Shared libraries can
7221 function perfectly well when stripped, since the symbols for
7222 dynamic linking are in a separate part of the ELF object
7224 You might also want to use the options
7225 <tt>--remove-section=.comment</tt> and
7226 <tt>--remove-section=.note</tt> on both shared libraries
7227 and executables, and <tt>--strip-debug</tt> on static
7233 Note that under some circumstances it may be useful to
7234 install a shared library unstripped, for example when
7235 building a separate package to support debugging.
7239 Shared object files (often <file>.so</file> files) that are not
7240 public libraries, that is, they are not meant to be linked
7241 to by third party executables (binaries of other packages),
7242 should be installed in subdirectories of the
7243 <file>/usr/lib</file> directory. Such files are exempt from the
7244 rules that govern ordinary shared libraries, except that
7245 they must not be installed executable and should be
7247 A common example are the so-called "plug-ins",
7248 internal shared objects that are dynamically loaded by
7249 programs using <manref name="dlopen" section="3">.
7254 An ever increasing number of packages are using
7255 <prgn>libtool</prgn> to do their linking. The latest GNU
7256 libtools (>= 1.3a) can take advantage of the metadata in the
7257 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
7258 files). The main advantage of <prgn>libtool</prgn>'s
7259 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
7260 store and subsequently access metadata with respect to the
7261 libraries it builds. <prgn>libtool</prgn> will search for
7262 those files, which contain a lot of useful information about
7263 a library (such as library dependency information for static
7264 linking). Also, they're <em>essential</em> for programs
7265 using <tt>libltdl</tt>.<footnote>
7266 Although <prgn>libtool</prgn> is fully capable of
7267 linking against shared libraries which don't have
7268 <tt>.la</tt> files, as it is a mere shell script it can
7269 add considerably to the build time of a
7270 <prgn>libtool</prgn>-using package if that shell script
7271 has to derive all this information from first principles
7272 for each library every time it is linked. With the
7273 advent of <prgn>libtool</prgn> version 1.4 (and to a
7274 lesser extent <prgn>libtool</prgn> version 1.3), the
7275 <file>.la</file> files also store information about
7276 inter-library dependencies which cannot necessarily be
7277 derived after the <file>.la</file> file is deleted.
7282 Packages that use <prgn>libtool</prgn> to create shared
7283 libraries should include the <file>.la</file> files in the
7284 <tt>-dev</tt> package, unless the package relies on
7285 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
7286 the <tt>.la</tt> files must go in the run-time library
7291 You must make sure that you use only released versions of
7292 shared libraries to build your packages; otherwise other
7293 users will not be able to run your binaries
7294 properly. Producing source packages that depend on
7295 unreleased compilers is also usually a bad
7302 <heading>Shared libraries</heading>
7304 This section has moved to <ref id="sharedlibs">.
7310 <heading>Scripts</heading>
7313 All command scripts, including the package maintainer
7314 scripts inside the package and used by <prgn>dpkg</prgn>,
7315 should have a <tt>#!</tt> line naming the shell to be used
7320 In the case of Perl scripts this should be
7321 <tt>#!/usr/bin/perl</tt>.
7325 When scripts are installed into a directory in the system
7326 PATH, the script name should not include an extension such
7327 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7328 language currently used to implement it.
7331 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>) other than
7332 <file>init.d</file> scripts should almost certainly start
7333 with <tt>set -e</tt> so that errors are detected.
7334 <file>init.d</file> scripts are something of a special case, due
7335 to how frequently they need to call commands that are allowed to
7336 fail, and it may instead be easier to check the exit status of
7337 commands directly. See <ref id="writing-init"> for more
7338 information about writing <file>init.d</file> scripts.
7341 Every script should use <tt>set -e</tt> or check the exit status
7342 of <em>every</em> command.
7345 Scripts may assume that <file>/bin/sh</file> implements the
7346 SUSv3 Shell Command Language<footnote>
7347 Single UNIX Specification, version 3, which is also IEEE
7348 1003.1-2004 (POSIX), and is available on the World Wide Web
7349 from <url id="http://www.unix.org/version3/online.html"
7350 name="The Open Group"> after free
7351 registration.</footnote>
7352 plus the following additional features not mandated by
7354 These features are in widespread use in the Linux community
7355 and are implemented in all of bash, dash, and ksh, the most
7356 common shells users may wish to use as <file>/bin/sh</file>.
7359 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7360 must not generate a newline.</item>
7361 <item><tt>test</tt>, if implemented as a shell built-in, must
7362 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7364 <item><tt>local</tt> to create a scoped variable must be
7365 supported, including listing multiple variables in a single
7366 local command and assigning a value to a variable at the
7367 same time as localizing it. <tt>local</tt> may or
7368 may not preserve the variable value from an outer scope if
7369 no assignment is present. Uses such as:
7373 # ... use a, b, c, d ...
7376 must be supported and must set the value of <tt>c</tt> to
7380 If a shell script requires non-SUSv3 features from the shell
7381 interpreter other than those listed above, the appropriate shell
7382 must be specified in the first line of the script (e.g.,
7383 <tt>#!/bin/bash</tt>) and the package must depend on the package
7384 providing the shell (unless the shell package is marked
7385 "Essential", as in the case of <prgn>bash</prgn>).
7389 You may wish to restrict your script to SUSv3 features plus the
7390 above set when possible so that it may use <file>/bin/sh</file>
7391 as its interpreter. If your script works with <prgn>dash</prgn>
7392 (originally called <prgn>ash</prgn>), it probably complies with
7393 the above requirements, but if you are in doubt, use
7394 <file>/bin/bash</file>.
7398 Perl scripts should check for errors when making any
7399 system calls, including <tt>open</tt>, <tt>print</tt>,
7400 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7404 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7405 scripting languages. See <em>Csh Programming Considered
7406 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7407 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7408 If an upstream package comes with <prgn>csh</prgn> scripts
7409 then you must make sure that they start with
7410 <tt>#!/bin/csh</tt> and make your package depend on the
7411 <prgn>c-shell</prgn> virtual package.
7415 Any scripts which create files in world-writeable
7416 directories (e.g., in <file>/tmp</file>) must use a
7417 mechanism which will fail atomically if a file with the same
7418 name already exists.
7422 The Debian base system provides the <prgn>tempfile</prgn>
7423 and <prgn>mktemp</prgn> utilities for use by scripts for
7430 <heading>Symbolic links</heading>
7433 In general, symbolic links within a top-level directory
7434 should be relative, and symbolic links pointing from one
7435 top-level directory into another should be absolute. (A
7436 top-level directory is a sub-directory of the root
7437 directory <file>/</file>.)
7441 In addition, symbolic links should be specified as short as
7442 possible, i.e., link targets like <file>foo/../bar</file> are
7447 Note that when creating a relative link using
7448 <prgn>ln</prgn> it is not necessary for the target of the
7449 link to exist relative to the working directory you're
7450 running <prgn>ln</prgn> from, nor is it necessary to change
7451 directory to the directory where the link is to be made.
7452 Simply include the string that should appear as the target
7453 of the link (this will be a pathname relative to the
7454 directory in which the link resides) as the first argument
7459 For example, in your <prgn>Makefile</prgn> or
7460 <file>debian/rules</file>, you can do things like:
7461 <example compact="compact">
7462 ln -fs gcc $(prefix)/bin/cc
7463 ln -fs gcc debian/tmp/usr/bin/cc
7464 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7465 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7470 A symbolic link pointing to a compressed file should always
7471 have the same file extension as the referenced file. (For
7472 example, if a file <file>foo.gz</file> is referenced by a
7473 symbolic link, the filename of the link has to end with
7474 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7479 <heading>Device files</heading>
7482 Packages must not include device files or named pipes in the
7487 If a package needs any special device files that are not
7488 included in the base system, it must call
7489 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7490 after notifying the user<footnote>
7491 This notification could be done via a (low-priority)
7492 debconf message, or an echo (printf) statement.
7497 Packages must not remove any device files in the
7498 <prgn>postrm</prgn> or any other script. This is left to the
7499 system administrator.
7503 Debian uses the serial devices
7504 <file>/dev/ttyS*</file>. Programs using the old
7505 <file>/dev/cu*</file> devices should be changed to use
7506 <file>/dev/ttyS*</file>.
7510 Named pipes needed by the package must be created in
7511 the <prgn>postinst</prgn> script<footnote>
7512 It's better to use <prgn>mkfifo</prgn> rather
7513 than <prgn>mknod</prgn> to create named pipes so that
7514 automated checks for packages incorrectly creating device
7515 files with <prgn>mknod</prgn> won't have false positives.
7516 </footnote> and removed in
7517 the <prgn>prerm</prgn> or <prgn>postrm</prgn> script as
7522 <sect id="config-files">
7523 <heading>Configuration files</heading>
7526 <heading>Definitions</heading>
7530 <tag>configuration file</tag>
7532 A file that affects the operation of a program, or
7533 provides site- or host-specific information, or
7534 otherwise customizes the behavior of a program.
7535 Typically, configuration files are intended to be
7536 modified by the system administrator (if needed or
7537 desired) to conform to local policy or to provide
7538 more useful site-specific behavior.
7541 <tag><tt>conffile</tt></tag>
7543 A file listed in a package's <tt>conffiles</tt>
7544 file, and is treated specially by <prgn>dpkg</prgn>
7545 (see <ref id="configdetails">).
7551 The distinction between these two is important; they are
7552 not interchangeable concepts. Almost all
7553 <tt>conffile</tt>s are configuration files, but many
7554 configuration files are not <tt>conffiles</tt>.
7558 As noted elsewhere, <file>/etc/init.d</file> scripts,
7559 <file>/etc/default</file> files, scripts installed in
7560 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7561 configuration installed in <file>/etc/cron.d</file> must be
7562 treated as configuration files. In general, any script that
7563 embeds configuration information is de-facto a configuration
7564 file and should be treated as such.
7569 <heading>Location</heading>
7572 Any configuration files created or used by your package
7573 must reside in <file>/etc</file>. If there are several,
7574 consider creating a subdirectory of <file>/etc</file>
7575 named after your package.
7579 If your package creates or uses configuration files
7580 outside of <file>/etc</file>, and it is not feasible to modify
7581 the package to use <file>/etc</file> directly, put the files
7582 in <file>/etc</file> and create symbolic links to those files
7583 from the location that the package requires.
7588 <heading>Behavior</heading>
7591 Configuration file handling must conform to the following
7593 <list compact="compact">
7595 local changes must be preserved during a package
7599 configuration files must be preserved when the
7600 package is removed, and only deleted when the
7604 Obsolete configuration files without local changes may be
7605 removed by the package during upgrade.
7609 The easy way to achieve this behavior is to make the
7610 configuration file a <tt>conffile</tt>. This is
7611 appropriate only if it is possible to distribute a default
7612 version that will work for most installations, although
7613 some system administrators may choose to modify it. This
7614 implies that the default version will be part of the
7615 package distribution, and must not be modified by the
7616 maintainer scripts during installation (or at any other
7621 In order to ensure that local changes are preserved
7622 correctly, no package may contain or make hard links to
7623 conffiles.<footnote>
7624 Rationale: There are two problems with hard links.
7625 The first is that some editors break the link while
7626 editing one of the files, so that the two files may
7627 unwittingly become unlinked and different. The second
7628 is that <prgn>dpkg</prgn> might break the hard link
7629 while upgrading <tt>conffile</tt>s.
7634 The other way to do it is via the maintainer scripts. In
7635 this case, the configuration file must not be listed as a
7636 <tt>conffile</tt> and must not be part of the package
7637 distribution. If the existence of a file is required for
7638 the package to be sensibly configured it is the
7639 responsibility of the package maintainer to provide
7640 maintainer scripts which correctly create, update and
7641 maintain the file and remove it on purge. (See <ref
7642 id="maintainerscripts"> for more information.) These
7643 scripts must be idempotent (i.e., must work correctly if
7644 <prgn>dpkg</prgn> needs to re-run them due to errors
7645 during installation or removal), must cope with all the
7646 variety of ways <prgn>dpkg</prgn> can call maintainer
7647 scripts, must not overwrite or otherwise mangle the user's
7648 configuration without asking, must not ask unnecessary
7649 questions (particularly during upgrades), and must
7650 otherwise be good citizens.
7654 The scripts are not required to configure every possible
7655 option for the package, but only those necessary to get
7656 the package running on a given system. Ideally the
7657 sysadmin should not have to do any configuration other
7658 than that done (semi-)automatically by the
7659 <prgn>postinst</prgn> script.
7663 A common practice is to create a script called
7664 <file><var>package</var>-configure</file> and have the
7665 package's <prgn>postinst</prgn> call it if and only if the
7666 configuration file does not already exist. In certain
7667 cases it is useful for there to be an example or template
7668 file which the maintainer scripts use. Such files should
7669 be in <file>/usr/share/<var>package</var></file> or
7670 <file>/usr/lib/<var>package</var></file> (depending on whether
7671 they are architecture-independent or not). There should
7672 be symbolic links to them from
7673 <file>/usr/share/doc/<var>package</var>/examples</file> if
7674 they are examples, and should be perfectly ordinary
7675 <prgn>dpkg</prgn>-handled files (<em>not</em>
7676 configuration files).
7680 These two styles of configuration file handling must
7681 not be mixed, for that way lies madness:
7682 <prgn>dpkg</prgn> will ask about overwriting the file
7683 every time the package is upgraded.
7688 <heading>Sharing configuration files</heading>
7691 Packages which specify the same file as a
7692 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7693 with each other. (This is an instance of the general rule
7694 about not sharing files. Note that neither alternatives
7695 nor diversions are likely to be appropriate in this case;
7696 in particular, <prgn>dpkg</prgn> does not handle diverted
7697 <tt>conffile</tt>s well.)
7701 The maintainer scripts must not alter a <tt>conffile</tt>
7702 of <em>any</em> package, including the one the scripts
7707 If two or more packages use the same configuration file
7708 and it is reasonable for both to be installed at the same
7709 time, one of these packages must be defined as
7710 <em>owner</em> of the configuration file, i.e., it will be
7711 the package which handles that file as a configuration
7712 file. Other packages that use the configuration file must
7713 depend on the owning package if they require the
7714 configuration file to operate. If the other package will
7715 use the configuration file if present, but is capable of
7716 operating without it, no dependency need be declared.
7720 If it is desirable for two or more related packages to
7721 share a configuration file <em>and</em> for all of the
7722 related packages to be able to modify that configuration
7723 file, then the following should be done:
7724 <enumlist compact="compact">
7726 One of the related packages (the "owning" package)
7727 will manage the configuration file with maintainer
7728 scripts as described in the previous section.
7731 The owning package should also provide a program
7732 that the other packages may use to modify the
7736 The related packages must use the provided program
7737 to make any desired modifications to the
7738 configuration file. They should either depend on
7739 the core package to guarantee that the configuration
7740 modifier program is available or accept gracefully
7741 that they cannot modify the configuration file if it
7742 is not. (This is in addition to the fact that the
7743 configuration file may not even be present in the
7750 Sometimes it's appropriate to create a new package which
7751 provides the basic infrastructure for the other packages
7752 and which manages the shared configuration files. (The
7753 <tt>sgml-base</tt> package is a good example.)
7758 <heading>User configuration files ("dotfiles")</heading>
7761 The files in <file>/etc/skel</file> will automatically be
7762 copied into new user accounts by <prgn>adduser</prgn>.
7763 No other program should reference the files in
7764 <file>/etc/skel</file>.
7768 Therefore, if a program needs a dotfile to exist in
7769 advance in <file>$HOME</file> to work sensibly, that dotfile
7770 should be installed in <file>/etc/skel</file> and treated as a
7775 However, programs that require dotfiles in order to
7776 operate sensibly are a bad thing, unless they do create
7777 the dotfiles themselves automatically.
7781 Furthermore, programs should be configured by the Debian
7782 default installation to behave as closely to the upstream
7783 default behavior as possible.
7787 Therefore, if a program in a Debian package needs to be
7788 configured in some way in order to operate sensibly, that
7789 should be done using a site-wide configuration file placed
7790 in <file>/etc</file>. Only if the program doesn't support a
7791 site-wide default configuration and the package maintainer
7792 doesn't have time to add it may a default per-user file be
7793 placed in <file>/etc/skel</file>.
7797 <file>/etc/skel</file> should be as empty as we can make it.
7798 This is particularly true because there is no easy (or
7799 necessarily desirable) mechanism for ensuring that the
7800 appropriate dotfiles are copied into the accounts of
7801 existing users when a package is installed.
7807 <heading>Log files</heading>
7809 Log files should usually be named
7810 <file>/var/log/<var>package</var>.log</file>. If you have many
7811 log files, or need a separate directory for permission
7812 reasons (<file>/var/log</file> is writable only by
7813 <file>root</file>), you should usually create a directory named
7814 <file>/var/log/<var>package</var></file> and place your log
7819 Log files must be rotated occasionally so that they don't
7820 grow indefinitely; the best way to do this is to drop a log
7821 rotation configuration file into the directory
7822 <file>/etc/logrotate.d</file> and use the facilities provided by
7823 logrotate.<footnote>
7825 The traditional approach to log files has been to set up
7826 <em>ad hoc</em> log rotation schemes using simple shell
7827 scripts and cron. While this approach is highly
7828 customizable, it requires quite a lot of sysadmin work.
7829 Even though the original Debian system helped a little
7830 by automatically installing a system which can be used
7831 as a template, this was deemed not enough.
7835 The use of <prgn>logrotate</prgn>, a program developed
7836 by Red Hat, is better, as it centralizes log management.
7837 It has both a configuration file
7838 (<file>/etc/logrotate.conf</file>) and a directory where
7839 packages can drop their individual log rotation
7840 configurations (<file>/etc/logrotate.d</file>).
7843 Here is a good example for a logrotate config
7844 file (for more information see <manref name="logrotate"
7846 <example compact="compact">
7847 /var/log/foo/*.log {
7852 /etc/init.d/foo force-reload
7856 This rotates all files under <file>/var/log/foo</file>, saves 12
7857 compressed generations, and forces the daemon to reload its
7858 configuration information after the log rotation.
7862 Log files should be removed when the package is
7863 purged (but not when it is only removed). This should be
7864 done by the <prgn>postrm</prgn> script when it is called
7865 with the argument <tt>purge</tt> (see <ref
7866 id="removedetails">).
7871 <heading>Permissions and owners</heading>
7874 The rules in this section are guidelines for general use.
7875 If necessary you may deviate from the details below.
7876 However, if you do so you must make sure that what is done
7877 is secure and you should try to be as consistent as possible
7878 with the rest of the system. You should probably also
7879 discuss it on <prgn>debian-devel</prgn> first.
7883 Files should be owned by <tt>root:root</tt>, and made
7884 writable only by the owner and universally readable (and
7885 executable, if appropriate), that is mode 644 or 755.
7889 Directories should be mode 755 or (for group-writability)
7890 mode 2775. The ownership of the directory should be
7891 consistent with its mode: if a directory is mode 2775, it
7892 should be owned by the group that needs write access to
7895 When a package is upgraded, and the owner or permissions
7896 of a file included in the package has changed, dpkg
7897 arranges for the ownership and permissions to be
7898 correctly set upon installation. However, this does not
7899 extend to directories; the permissions and ownership of
7900 directories already on the system does not change on
7901 install or upgrade of packages. This makes sense, since
7902 otherwise common directories like <tt>/usr</tt> would
7903 always be in flux. To correctly change permissions of a
7904 directory the package owns, explicit action is required,
7905 usually in the <tt>postinst</tt> script. Care must be
7906 taken to handle downgrades as well, in that case.
7913 Setuid and setgid executables should be mode 4755 or 2755
7914 respectively, and owned by the appropriate user or group.
7915 They should not be made unreadable (modes like 4711 or
7916 2711 or even 4111); doing so achieves no extra security,
7917 because anyone can find the binary in the freely available
7918 Debian package; it is merely inconvenient. For the same
7919 reason you should not restrict read or execute permissions
7920 on non-set-id executables.
7924 Some setuid programs need to be restricted to particular
7925 sets of users, using file permissions. In this case they
7926 should be owned by the uid to which they are set-id, and by
7927 the group which should be allowed to execute them. They
7928 should have mode 4754; again there is no point in making
7929 them unreadable to those users who must not be allowed to
7934 It is possible to arrange that the system administrator can
7935 reconfigure the package to correspond to their local
7936 security policy by changing the permissions on a binary:
7937 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7938 described below.<footnote>
7939 Ordinary files installed by <prgn>dpkg</prgn> (as
7940 opposed to <tt>conffile</tt>s and other similar objects)
7941 normally have their permissions reset to the distributed
7942 permissions when the package is reinstalled. However,
7943 the use of <prgn>dpkg-statoverride</prgn> overrides this
7946 Another method you should consider is to create a group for
7947 people allowed to use the program(s) and make any setuid
7948 executables executable only by that group.
7952 If you need to create a new user or group for your package
7953 there are two possibilities. Firstly, you may need to
7954 make some files in the binary package be owned by this
7955 user or group, or you may need to compile the user or
7956 group id (rather than just the name) into the binary
7957 (though this latter should be avoided if possible, as in
7958 this case you need a statically allocated id).</p>
7961 If you need a statically allocated id, you must ask for a
7962 user or group id from the <tt>base-passwd</tt> maintainer,
7963 and must not release the package until you have been
7964 allocated one. Once you have been allocated one you must
7965 either make the package depend on a version of the
7966 <tt>base-passwd</tt> package with the id present in
7967 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7968 your package to create the user or group itself with the
7969 correct id (using <tt>adduser</tt>) in its
7970 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7971 the <prgn>postinst</prgn> is to be preferred if it is
7972 possible, otherwise a pre-dependency will be needed on the
7973 <tt>adduser</tt> package.)
7977 On the other hand, the program might be able to determine
7978 the uid or gid from the user or group name at runtime, so
7979 that a dynamically allocated id can be used. In this case
7980 you should choose an appropriate user or group name,
7981 discussing this on <prgn>debian-devel</prgn> and checking
7982 with the <package/base-passwd/ maintainer that it is unique and that
7983 they do not wish you to use a statically allocated id
7984 instead. When this has been checked you must arrange for
7985 your package to create the user or group if necessary using
7986 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7987 <prgn>postinst</prgn> script (again, the latter is to be
7988 preferred if it is possible).
7992 Note that changing the numeric value of an id associated
7993 with a name is very difficult, and involves searching the
7994 file system for all appropriate files. You need to think
7995 carefully whether a static or dynamic id is required, since
7996 changing your mind later will cause problems.
7999 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
8001 This section is not intended as policy, but as a
8002 description of the use of <prgn>dpkg-statoverride</prgn>.
8006 If a system administrator wishes to have a file (or
8007 directory or other such thing) installed with owner and
8008 permissions different from those in the distributed Debian
8009 package, they can use the <prgn>dpkg-statoverride</prgn>
8010 program to instruct <prgn>dpkg</prgn> to use the different
8011 settings every time the file is installed. Thus the
8012 package maintainer should distribute the files with their
8013 normal permissions, and leave it for the system
8014 administrator to make any desired changes. For example, a
8015 daemon which is normally required to be setuid root, but
8016 in certain situations could be used without being setuid,
8017 should be installed setuid in the <tt>.deb</tt>. Then the
8018 local system administrator can change this if they wish.
8019 If there are two standard ways of doing it, the package
8020 maintainer can use <tt>debconf</tt> to find out the
8021 preference, and call <prgn>dpkg-statoverride</prgn> in the
8022 maintainer script if necessary to accommodate the system
8023 administrator's choice. Care must be taken during
8024 upgrades to not override an existing setting.
8028 Given the above, <prgn>dpkg-statoverride</prgn> is
8029 essentially a tool for system administrators and would not
8030 normally be needed in the maintainer scripts. There is
8031 one type of situation, though, where calls to
8032 <prgn>dpkg-statoverride</prgn> would be needed in the
8033 maintainer scripts, and that involves packages which use
8034 dynamically allocated user or group ids. In such a
8035 situation, something like the following idiom can be very
8036 helpful in the package's <prgn>postinst</prgn>, where
8037 <tt>sysuser</tt> is a dynamically allocated id:
8039 for i in /usr/bin/foo /usr/sbin/bar
8041 # only do something when no setting exists
8042 if ! dpkg-statoverride --list $i >/dev/null 2>&1
8044 #include: debconf processing, question about foo and bar
8045 if [ "$RET" = "true" ] ; then
8046 dpkg-statoverride --update --add sysuser root 4755 $i
8051 The corresponding code to remove the override when the package
8054 for i in /usr/bin/foo /usr/sbin/bar
8056 if dpkg-statoverride --list $i >/dev/null 2>&1
8058 dpkg-statoverride --remove $i
8068 <chapt id="customized-programs">
8069 <heading>Customized programs</heading>
8071 <sect id="arch-spec">
8072 <heading>Architecture specification strings</heading>
8075 If a program needs to specify an <em>architecture specification
8076 string</em> in some place, it should select one of the strings
8077 provided by <tt>dpkg-architecture -L</tt>. The strings are in
8078 the format <tt><var>os</var>-<var>arch</var></tt>, though the OS
8079 part is sometimes elided, as when the OS is Linux.
8083 Note that we don't want to use
8084 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
8085 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
8086 since this would make our programs incompatible with other
8087 Linux distributions. We also don't use something like
8088 <tt><var>arch</var>-unknown-linux</tt>, since the
8089 <tt>unknown</tt> does not look very good.
8092 <sect1 id="arch-wildcard-spec">
8093 <heading>Architecture wildcards</heading>
8096 A package may specify an architecture wildcard. Architecture
8097 wildcards are in the format <tt>any</tt> (which matches every
8098 architecture), <tt><var>os</var></tt>-any, or
8099 any-<tt><var>cpu</var></tt>. <footnote>
8100 Internally, the package system normalizes the GNU triplets
8101 and the Debian arches into Debian arch triplets (which are
8102 kind of inverted GNU triplets), with the first component of
8103 the triplet representing the libc and ABI in use, and then
8104 does matching against those triplets. However, such
8105 triplets are an internal implementation detail that should
8106 not be used by packages directly. The libc and ABI portion
8107 is handled internally by the package system based on
8108 the <var>os</var> and <var>cpu</var>.
8115 <heading>Daemons</heading>
8118 The configuration files <file>/etc/services</file>,
8119 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
8120 by the <prgn>netbase</prgn> package and must not be modified
8125 If a package requires a new entry in one of these files, the
8126 maintainer should get in contact with the
8127 <prgn>netbase</prgn> maintainer, who will add the entries
8128 and release a new version of the <prgn>netbase</prgn>
8133 The configuration file <file>/etc/inetd.conf</file> must not be
8134 modified by the package's scripts except via the
8135 <prgn>update-inetd</prgn> script or the
8136 <file>DebianNet.pm</file> Perl module. See their documentation
8137 for details on how to add entries.
8141 If a package wants to install an example entry into
8142 <file>/etc/inetd.conf</file>, the entry must be preceded with
8143 exactly one hash character (<tt>#</tt>). Such lines are
8144 treated as "commented out by user" by the
8145 <prgn>update-inetd</prgn> script and are not changed or
8146 activated during package updates.
8151 <heading>Using pseudo-ttys and modifying wtmp, utmp and
8155 Some programs need to create pseudo-ttys. This should be done
8156 using Unix98 ptys if the C library supports it. The resulting
8157 program must not be installed setuid root, unless that
8158 is required for other functionality.
8162 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
8163 <file>/var/log/lastlog</file> must be installed writable by
8164 group <tt>utmp</tt>. Programs which need to modify those
8165 files must be installed setgid <tt>utmp</tt>.
8170 <heading>Editors and pagers</heading>
8173 Some programs have the ability to launch an editor or pager
8174 program to edit or display a text document. Since there are
8175 lots of different editors and pagers available in the Debian
8176 distribution, the system administrator and each user should
8177 have the possibility to choose their preferred editor and
8182 In addition, every program should choose a good default
8183 editor/pager if none is selected by the user or system
8188 Thus, every program that launches an editor or pager must
8189 use the EDITOR or PAGER environment variable to determine
8190 the editor or pager the user wishes to use. If these
8191 variables are not set, the programs <file>/usr/bin/editor</file>
8192 and <file>/usr/bin/pager</file> should be used, respectively.
8196 These two files are managed through the <prgn>dpkg</prgn>
8197 "alternatives" mechanism. Thus every package providing an
8198 editor or pager must call the
8199 <prgn>update-alternatives</prgn> script to register these
8204 If it is very hard to adapt a program to make use of the
8205 EDITOR or PAGER variables, that program may be configured to
8206 use <file>/usr/bin/sensible-editor</file> and
8207 <file>/usr/bin/sensible-pager</file> as the editor or pager
8208 program respectively. These are two scripts provided in the
8209 <package>sensible-utils</package> package that check the EDITOR
8210 and PAGER variables and launch the appropriate program, and fall
8211 back to <file>/usr/bin/editor</file>
8212 and <file>/usr/bin/pager</file> if the variable is not set.
8216 A program may also use the VISUAL environment variable to
8217 determine the user's choice of editor. If it exists, it
8218 should take precedence over EDITOR. This is in fact what
8219 <file>/usr/bin/sensible-editor</file> does.
8223 It is not required for a package to depend on
8224 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
8225 package to provide such virtual packages.<footnote>
8226 The Debian base system already provides an editor and a
8232 <sect id="web-appl">
8233 <heading>Web servers and applications</heading>
8236 This section describes the locations and URLs that should
8237 be used by all web servers and web applications in the
8244 Cgi-bin executable files are installed in the
8246 <example compact="compact">
8247 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
8249 or a subdirectory of that directory, and should be
8251 <example compact="compact">
8252 http://localhost/cgi-bin/<var>cgi-bin-name</var>
8254 (possibly with a subdirectory name
8255 before <var>cgi-bin-name</var>).
8259 <p>Access to HTML documents</p>
8262 HTML documents for a package are stored in
8263 <file>/usr/share/doc/<var>package</var></file>
8264 and can be referred to as
8265 <example compact="compact">
8266 http://localhost/doc/<var>package</var>/<var>filename</var>
8271 The web server should restrict access to the document
8272 tree so that only clients on the same host can read
8273 the documents. If the web server does not support such
8274 access controls, then it should not provide access at
8275 all, or ask about providing access during installation.
8280 <p>Access to images</p>
8282 It is recommended that images for a package be stored
8283 in <tt>/usr/share/images/<var>package</var></tt> and
8284 may be referred to through an alias <tt>/images/</tt>
8287 http://localhost/images/<package>/<filename>
8294 <p>Web Document Root</p>
8297 Web Applications should try to avoid storing files in
8298 the Web Document Root. Instead they should use the
8299 /usr/share/doc/<var>package</var> directory for
8300 documents and register the Web Application via the
8301 <package>doc-base</package> package. If access to the
8302 web document root is unavoidable then use
8303 <example compact="compact">
8306 as the Document Root. This might be just a symbolic
8307 link to the location where the system administrator
8308 has put the real document root.
8311 <item><p>Providing httpd and/or httpd-cgi</p>
8313 All web servers should provide the virtual package
8314 <tt>httpd</tt>. If a web server has CGI support it should
8315 provide <tt>httpd-cgi</tt> additionally.
8318 All web applications which do not contain CGI scripts should
8319 depend on <tt>httpd</tt>, all those web applications which
8320 <tt>do</tt> contain CGI scripts, should depend on
8328 <sect id="mail-transport-agents">
8329 <heading>Mail transport, delivery and user agents</heading>
8332 Debian packages which process electronic mail, whether mail
8333 user agents (MUAs) or mail transport agents (MTAs), must
8334 ensure that they are compatible with the configuration
8335 decisions below. Failure to do this may result in lost
8336 mail, broken <tt>From:</tt> lines, and other serious brain
8341 The mail spool is <file>/var/mail</file> and the interface to
8342 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8343 the FHS). On older systems, the mail spool may be
8344 physically located in <file>/var/spool/mail</file>, but all
8345 access to the mail spool should be via the
8346 <file>/var/mail</file> symlink. The mail spool is part of the
8347 base system and not part of the MTA package.
8351 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8352 programs (such as IMAP daemons) must lock the mailbox in an
8353 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8354 be combined with dot locking. To avoid deadlocks, a program
8355 should use <tt>fcntl()</tt> first and dot locking after
8356 this, or alternatively implement the two locking methods in
8357 a non blocking way<footnote>
8358 If it is not possible to establish both locks, the
8359 system shouldn't wait for the second lock to be
8360 established, but remove the first lock, wait a (random)
8361 time, and start over locking again.
8362 </footnote>. Using the functions <tt>maillock</tt> and
8363 <tt>mailunlock</tt> provided by the
8364 <tt>liblockfile*</tt><footnote>
8365 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8366 to use these functions.
8367 </footnote> packages is the recommended way to realize this.
8371 Mailboxes are generally either mode 600 and owned by
8372 <var>user</var> or mode 660 and owned by
8373 <tt><var>user</var>:mail</tt><footnote>
8374 There are two traditional permission schemes for mail spools:
8375 mode 600 with all mail delivery done by processes running as
8376 the destination user, or mode 660 and owned by group mail with
8377 mail delivery done by a process running as a system user in
8378 group mail. Historically, Debian required mode 660 mail
8379 spools to enable the latter model, but that model has become
8380 increasingly uncommon and the principle of least privilege
8381 indicates that mail systems that use the first model should
8382 use permissions of 600. If delivery to programs is permitted,
8383 it's easier to keep the mail system secure if the delivery
8384 agent runs as the destination user. Debian Policy therefore
8385 permits either scheme.
8386 </footnote>. The local system administrator may choose a
8387 different permission scheme; packages should not make
8388 assumptions about the permission and ownership of mailboxes
8389 unless required (such as when creating a new mailbox). A MUA
8390 may remove a mailbox (unless it has nonstandard permissions) in
8391 which case the MTA or another MUA must recreate it if needed.
8395 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8396 be setgid mail to do the locking mentioned above (and
8397 must obviously avoid accessing other users' mailboxes
8398 using this privilege).</p>
8401 <file>/etc/aliases</file> is the source file for the system mail
8402 aliases (e.g., postmaster, usenet, etc.), it is the one
8403 which the sysadmin and <prgn>postinst</prgn> scripts may
8404 edit. After <file>/etc/aliases</file> is edited the program or
8405 human editing it must call <prgn>newaliases</prgn>. All MTA
8406 packages must come with a <prgn>newaliases</prgn> program,
8407 even if it does nothing, but older MTA packages did not do
8408 this so programs should not fail if <prgn>newaliases</prgn>
8409 cannot be found. Note that because of this, all MTA
8410 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8411 <tt>Replaces: mail-transport-agent</tt> control file
8416 The convention of writing <tt>forward to
8417 <var>address</var></tt> in the mailbox itself is not
8418 supported. Use a <tt>.forward</tt> file instead.</p>
8421 The <prgn>rmail</prgn> program used by UUCP
8422 for incoming mail should be <file>/usr/sbin/rmail</file>.
8423 Likewise, <prgn>rsmtp</prgn>, for receiving
8424 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8428 If your package needs to know what hostname to use on (for
8429 example) outgoing news and mail messages which are generated
8430 locally, you should use the file <file>/etc/mailname</file>. It
8431 will contain the portion after the username and <tt>@</tt>
8432 (at) sign for email addresses of users on the machine
8433 (followed by a newline).
8437 Such a package should check for the existence of this file
8438 when it is being configured. If it exists, it should be
8439 used without comment, although an MTA's configuration script
8440 may wish to prompt the user even if it finds that this file
8441 exists. If the file does not exist, the package should
8442 prompt the user for the value (preferably using
8443 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8444 as well as using it in the package's configuration. The
8445 prompt should make it clear that the name will not just be
8446 used by that package. For example, in this situation the
8447 <tt>inn</tt> package could say something like:
8448 <example compact="compact">
8449 Please enter the "mail name" of your system. This is the
8450 hostname portion of the address to be shown on outgoing
8451 news and mail messages. The default is
8452 <var>syshostname</var>, your system's host name. Mail
8453 name ["<var>syshostname</var>"]:
8455 where <var>syshostname</var> is the output of <tt>hostname
8461 <heading>News system configuration</heading>
8464 All the configuration files related to the NNTP (news)
8465 servers and clients should be located under
8466 <file>/etc/news</file>.</p>
8469 There are some configuration issues that apply to a number
8470 of news clients and server packages on the machine. These
8474 <tag><file>/etc/news/organization</file></tag>
8476 A string which should appear as the
8477 organization header for all messages posted
8478 by NNTP clients on the machine
8481 <tag><file>/etc/news/server</file></tag>
8483 Contains the FQDN of the upstream NNTP
8484 server, or localhost if the local machine is
8489 Other global files may be added as required for cross-package news
8496 <heading>Programs for the X Window System</heading>
8499 <heading>Providing X support and package priorities</heading>
8502 Programs that can be configured with support for the X
8503 Window System must be configured to do so and must declare
8504 any package dependencies necessary to satisfy their
8505 runtime requirements when using the X Window System. If
8506 such a package is of higher priority than the X packages
8507 on which it depends, it is required that either the
8508 X-specific components be split into a separate package, or
8509 that an alternative version of the package, which includes
8510 X support, be provided, or that the package's priority be
8516 <heading>Packages providing an X server</heading>
8519 Packages that provide an X server that, directly or
8520 indirectly, communicates with real input and display
8521 hardware should declare in their control data that they
8522 provide the virtual package <tt>xserver</tt>.<footnote>
8523 This implements current practice, and provides an
8524 actual policy for usage of the <tt>xserver</tt>
8525 virtual package which appears in the virtual packages
8526 list. In a nutshell, X servers that interface
8527 directly with the display and input hardware or via
8528 another subsystem (e.g., GGI) should provide
8529 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8530 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8536 <heading>Packages providing a terminal emulator</heading>
8539 Packages that provide a terminal emulator for the X Window
8540 System which meet the criteria listed below should declare
8541 in their control data that they provide the virtual
8542 package <tt>x-terminal-emulator</tt>. They should also
8543 register themselves as an alternative for
8544 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8549 To be an <tt>x-terminal-emulator</tt>, a program must:
8550 <list compact="compact">
8552 Be able to emulate a DEC VT100 terminal, or a
8553 compatible terminal.
8557 Support the command-line option <tt>-e
8558 <var>command</var></tt>, which creates a new
8559 terminal window<footnote>
8560 "New terminal window" does not necessarily mean
8561 a new top-level X window directly parented by
8562 the window manager; it could, if the terminal
8563 emulator application were so coded, be a new
8564 "view" in a multiple-document interface (MDI).
8566 and runs the specified <var>command</var>,
8567 interpreting the entirety of the rest of the command
8568 line as a command to pass straight to exec, in the
8569 manner that <tt>xterm</tt> does.
8573 Support the command-line option <tt>-T
8574 <var>title</var></tt>, which creates a new terminal
8575 window with the window title <var>title</var>.
8582 <heading>Packages providing a window manager</heading>
8585 Packages that provide a window manager should declare in
8586 their control data that they provide the virtual package
8587 <tt>x-window-manager</tt>. They should also register
8588 themselves as an alternative for
8589 <file>/usr/bin/x-window-manager</file>, with a priority
8590 calculated as follows:
8591 <list compact="compact">
8593 Start with a priority of 20.
8597 If the window manager supports the Debian menu
8598 system, add 20 points if this support is available
8599 in the package's default configuration (i.e., no
8600 configuration files belonging to the system or user
8601 have to be edited to activate the feature); if
8602 configuration files must be modified, add only 10
8608 If the window manager complies with <url
8609 id="http://www.freedesktop.org/Standards/wm-spec"
8610 name="The Window Manager Specification Project">,
8611 written by the <url id="http://www.freedesktop.org/"
8612 name="Free Desktop Group">, add 40 points.
8616 If the window manager permits the X session to be
8617 restarted using a <em>different</em> window manager
8618 (without killing the X server) in its default
8619 configuration, add 10 points; otherwise add none.
8626 <heading>Packages providing fonts</heading>
8629 Packages that provide fonts for the X Window
8631 For the purposes of Debian Policy, a "font for the X
8632 Window System" is one which is accessed via X protocol
8633 requests. Fonts for the Linux console, for PostScript
8634 renderer, or any other purpose, do not fit this
8635 definition. Any tool which makes such fonts available
8636 to the X Window System, however, must abide by this
8639 must do a number of things to ensure that they are both
8640 available without modification of the X or font server
8641 configuration, and that they do not corrupt files used by
8642 other font packages to register information about
8646 Fonts of any type supported by the X Window System
8647 must be in a separate binary package from any
8648 executables, libraries, or documentation (except
8649 that specific to the fonts shipped, such as their
8650 license information). If one or more of the fonts
8651 so packaged are necessary for proper operation of
8652 the package with which they are associated the font
8653 package may be Recommended; if the fonts merely
8654 provide an enhancement, a Suggests relationship may
8655 be used. Packages must not Depend on font
8657 This is because the X server may retrieve fonts
8658 from the local file system or over the network
8659 from an X font server; the Debian package system
8660 is empowered to deal only with the local
8666 BDF fonts must be converted to PCF fonts with the
8667 <prgn>bdftopcf</prgn> utility (available in the
8668 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8669 placed in a directory that corresponds to their
8671 <list compact="compact">
8673 100 dpi fonts must be placed in
8674 <file>/usr/share/fonts/X11/100dpi/</file>.
8678 75 dpi fonts must be placed in
8679 <file>/usr/share/fonts/X11/75dpi/</file>.
8683 Character-cell fonts, cursor fonts, and other
8684 low-resolution fonts must be placed in
8685 <file>/usr/share/fonts/X11/misc/</file>.
8691 Type 1 fonts must be placed in
8692 <file>/usr/share/fonts/X11/Type1/</file>. If font
8693 metric files are available, they must be placed here
8698 Subdirectories of <file>/usr/share/fonts/X11/</file>
8699 other than those listed above must be neither
8700 created nor used. (The <file>PEX</file>, <file>CID</file>,
8701 <file>Speedo</file>, and <file>cyrillic</file> directories
8702 are excepted for historical reasons, but installation of
8703 files into these directories remains discouraged.)
8707 Font packages may, instead of placing files directly
8708 in the X font directories listed above, provide
8709 symbolic links in that font directory pointing to
8710 the files' actual location in the filesystem. Such
8711 a location must comply with the FHS.
8715 Font packages should not contain both 75dpi and
8716 100dpi versions of a font. If both are available,
8717 they should be provided in separate binary packages
8718 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8719 the names of the packages containing the
8720 corresponding fonts.
8724 Fonts destined for the <file>misc</file> subdirectory
8725 should not be included in the same package as 75dpi
8726 or 100dpi fonts; instead, they should be provided in
8727 a separate package with <tt>-misc</tt> appended to
8732 Font packages must not provide the files
8733 <file>fonts.dir</file>, <file>fonts.alias</file>, or
8734 <file>fonts.scale</file> in a font directory:
8737 <file>fonts.dir</file> files must not be provided at all.
8741 <file>fonts.alias</file> and <file>fonts.scale</file>
8742 files, if needed, should be provided in the
8744 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
8745 where <var>fontdir</var> is the name of the
8747 <file>/usr/share/fonts/X11/</file> where the
8748 package's corresponding fonts are stored
8749 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
8750 <var>package</var> is the name of the package
8751 that provides these fonts, and
8752 <var>extension</var> is either <tt>scale</tt>
8753 or <tt>alias</tt>, whichever corresponds to
8760 Font packages must declare a dependency on
8761 <tt>xfonts-utils</tt> in their control
8766 Font packages that provide one or more
8767 <file>fonts.scale</file> files as described above must
8768 invoke <prgn>update-fonts-scale</prgn> on each
8769 directory into which they installed fonts
8770 <em>before</em> invoking
8771 <prgn>update-fonts-dir</prgn> on that directory.
8772 This invocation must occur in both the
8773 <prgn>postinst</prgn> (for all arguments) and
8774 <prgn>postrm</prgn> (for all arguments except
8775 <tt>upgrade</tt>) scripts.
8779 Font packages that provide one or more
8780 <file>fonts.alias</file> files as described above must
8781 invoke <prgn>update-fonts-alias</prgn> on each
8782 directory into which they installed fonts. This
8783 invocation must occur in both the
8784 <prgn>postinst</prgn> (for all arguments) and
8785 <prgn>postrm</prgn> (for all arguments except
8786 <tt>upgrade</tt>) scripts.
8790 Font packages must invoke
8791 <prgn>update-fonts-dir</prgn> on each directory into
8792 which they installed fonts. This invocation must
8793 occur in both the <prgn>postinst</prgn> (for all
8794 arguments) and <prgn>postrm</prgn> (for all
8795 arguments except <tt>upgrade</tt>) scripts.
8799 Font packages must not provide alias names for the
8800 fonts they include which collide with alias names
8801 already in use by fonts already packaged.
8805 Font packages must not provide fonts with the same
8806 XLFD registry name as another font already packaged.
8812 <sect1 id="appdefaults">
8813 <heading>Application defaults files</heading>
8816 Application defaults files must be installed in the
8817 directory <file>/etc/X11/app-defaults/</file> (use of a
8818 localized subdirectory of <file>/etc/X11/</file> as described
8819 in the <em>X Toolkit Intrinsics - C Language
8820 Interface</em> manual is also permitted). They must be
8821 registered as <tt>conffile</tt>s or handled as
8822 configuration files.
8826 Customization of programs' X resources may also be
8827 supported with the provision of a file with the same name
8828 as that of the package placed in
8829 the <file>/etc/X11/Xresources/</file> directory, which
8830 must be registered as a <tt>conffile</tt> or handled as a
8831 configuration file.<footnote>
8832 Note that this mechanism is not the same as using
8833 app-defaults; app-defaults are tied to the client
8834 binary on the local file system, whereas X resources
8835 are stored in the X server and affect all connecting
8842 <heading>Installation directory issues</heading>
8845 Historically, packages using the X Window System used a
8846 separate set of installation directories from other packages.
8847 This practice has been discontinued and packages using the X
8848 Window System should now generally be installed in the same
8849 directories as any other package. Specifically, packages must
8850 not install files under the <file>/usr/X11R6/</file> directory
8851 and the <file>/usr/X11R6/</file> directory hierarchy should be
8852 regarded as obsolete.
8856 Include files previously installed under
8857 <file>/usr/X11R6/include/X11/</file> should be installed into
8858 <file>/usr/include/X11/</file>. For files previously
8859 installed into subdirectories of
8860 <file>/usr/X11R6/lib/X11/</file>, package maintainers should
8861 determine if subdirectories of <file>/usr/lib/</file> and
8862 <file>/usr/share/</file> can be used. If not, a subdirectory
8863 of <file>/usr/lib/X11/</file> should be used.
8867 Configuration files for window, display, or session managers
8868 or other applications that are tightly integrated with the X
8869 Window System may be placed in a subdirectory
8870 of <file>/etc/X11/</file> corresponding to the package name.
8871 Other X Window System applications should use
8872 the <file>/etc/</file> directory unless otherwise mandated by
8873 policy (such as for <ref id="appdefaults">).
8878 <heading>The OSF/Motif and OpenMotif libraries</heading>
8881 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8882 OpenMotif libraries</em><footnote>
8883 OSF/Motif and OpenMotif are collectively referred to as
8884 "Motif" in this policy document.
8886 should be compiled against and tested with LessTif (a free
8887 re-implementation of Motif) instead. If the maintainer
8888 judges that the program or programs do not work
8889 sufficiently well with LessTif to be distributed and
8890 supported, but do so when compiled against Motif, then two
8891 versions of the package should be created; one linked
8892 statically against Motif and with <tt>-smotif</tt>
8893 appended to the package name, and one linked dynamically
8894 against Motif and with <tt>-dmotif</tt> appended to the
8899 Both Motif-linked versions are dependent
8900 upon non-DFSG-compliant software and thus cannot be
8901 uploaded to the <em>main</em> distribution; if the
8902 software is itself DFSG-compliant it may be uploaded to
8903 the <em>contrib</em> distribution. While known existing
8904 versions of Motif permit unlimited redistribution of
8905 binaries linked against the library (whether statically or
8906 dynamically), it is the package maintainer's
8907 responsibility to determine whether this is permitted by
8908 the license of the copy of Motif in their possession.
8914 <heading>Perl programs and modules</heading>
8917 Perl programs and modules should follow the current Perl policy.
8921 The Perl policy can be found in the <tt>perl-policy</tt>
8922 files in the <tt>debian-policy</tt> package.
8923 It is also available from the Debian web mirrors at
8924 <tt><url name="/doc/packaging-manuals/perl-policy/"
8925 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8930 <heading>Emacs lisp programs</heading>
8933 Please refer to the "Debian Emacs Policy" for details of how to
8934 package emacs lisp programs.
8938 The Emacs policy is available in
8939 <file>debian-emacs-policy.gz</file> of the
8940 <package>emacsen-common</package> package.
8941 It is also available from the Debian web mirrors at
8942 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8943 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8948 <heading>Games</heading>
8951 The permissions on <file>/var/games</file> are mode 755, owner
8952 <tt>root</tt> and group <tt>root</tt>.
8956 Each game decides on its own security policy.</p>
8959 Games which require protected, privileged access to
8960 high-score files, saved games, etc., may be made
8961 set-<em>group</em>-id (mode 2755) and owned by
8962 <tt>root:games</tt>, and use files and directories with
8963 appropriate permissions (770 <tt>root:games</tt>, for
8964 example). They must not be made
8965 set-<em>user</em>-id, as this causes security problems. (If
8966 an attacker can subvert any set-user-id game they can
8967 overwrite the executable of any other, causing other players
8968 of these games to run a Trojan horse program. With a
8969 set-group-id game the attacker only gets access to less
8970 important game data, and if they can get at the other
8971 players' accounts at all it will take considerably more
8975 Some packages, for example some fortune cookie programs, are
8976 configured by the upstream authors to install with their
8977 data files or other static information made unreadable so
8978 that they can only be accessed through set-id programs
8979 provided. You should not do this in a Debian package: anyone can
8980 download the <file>.deb</file> file and read the data from it,
8981 so there is no point making the files unreadable. Not
8982 making the files unreadable also means that you don't have
8983 to make so many programs set-id, which reduces the risk of a
8987 As described in the FHS, binaries of games should be
8988 installed in the directory <file>/usr/games</file>. This also
8989 applies to games that use the X Window System. Manual pages
8990 for games (X and non-X games) should be installed in
8991 <file>/usr/share/man/man6</file>.</p>
8997 <heading>Documentation</heading>
9000 <heading>Manual pages</heading>
9003 You should install manual pages in <prgn>nroff</prgn> source
9004 form, in appropriate places under <file>/usr/share/man</file>.
9005 You should only use sections 1 to 9 (see the FHS for more
9006 details). You must not install a pre-formatted "cat page".
9010 Each program, utility, and function should have an
9011 associated manual page included in the same package. It is
9012 suggested that all configuration files also have a manual
9013 page included as well. Manual pages for protocols and other
9014 auxiliary things are optional.
9018 If no manual page is available, this is considered as a bug
9019 and should be reported to the Debian Bug Tracking System (the
9020 maintainer of the package is allowed to write this bug report
9021 themselves, if they so desire). Do not close the bug report
9022 until a proper man page is available.<footnote>
9023 It is not very hard to write a man page. See the
9024 <url id="http://www.schweikhardt.net/man_page_howto.html"
9025 name="Man-Page-HOWTO">,
9026 <manref name="man" section="7">, the examples
9027 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
9028 the helper program <prgn>help2man</prgn>, or the
9029 directory <file>/usr/share/doc/man-db/examples</file>.
9034 You may forward a complaint about a missing man page to the
9035 upstream authors, and mark the bug as forwarded in the
9036 Debian bug tracking system. Even though the GNU Project do
9037 not in general consider the lack of a man page to be a bug,
9038 we do; if they tell you that they don't consider it a bug
9039 you should leave the bug in our bug tracking system open
9044 Manual pages should be installed compressed using <tt>gzip -9</tt>.
9048 If one man page needs to be accessible via several names it
9049 is better to use a symbolic link than the <file>.so</file>
9050 feature, but there is no need to fiddle with the relevant
9051 parts of the upstream source to change from <file>.so</file> to
9052 symlinks: don't do it unless it's easy. You should not
9053 create hard links in the manual page directories, nor put
9054 absolute filenames in <file>.so</file> directives. The filename
9055 in a <file>.so</file> in a man page should be relative to the
9056 base of the man page tree (usually
9057 <file>/usr/share/man</file>). If you do not create any links
9058 (whether symlinks, hard links, or <tt>.so</tt> directives)
9059 in the file system to the alternate names of the man page,
9060 then you should not rely on <prgn>man</prgn> finding your
9061 man page under those names based solely on the information in
9062 the man page's header.<footnote>
9063 Supporting this in <prgn>man</prgn> often requires
9064 unreasonable processing time to find a manual page or to
9065 report that none exists, and moves knowledge into man's
9066 database that would be better left in the file system.
9067 This support is therefore deprecated and will cease to
9068 be present in the future.
9073 Manual pages in locale-specific subdirectories of
9074 <file>/usr/share/man</file> should use either UTF-8 or the usual
9075 legacy encoding for that language (normally the one corresponding
9076 to the shortest relevant locale name in
9077 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
9078 <file>/usr/share/man/fr</file> should use either UTF-8 or
9079 ISO-8859-1.<footnote>
9080 <prgn>man</prgn> will automatically detect whether UTF-8 is in
9081 use. In future, all manual pages will be required to use
9087 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
9088 included in the subdirectory name unless it indicates a
9089 significant difference in the language, as this excludes
9090 speakers of the language in other countries.<footnote>
9091 At the time of writing, Chinese and Portuguese are the main
9092 languages with such differences, so <file>pt_BR</file>,
9093 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
9098 If a localized version of a manual page is provided, it should
9099 either be up-to-date or it should be obvious to the reader that
9100 it is outdated and the original manual page should be used
9101 instead. This can be done either by a note at the beginning of
9102 the manual page or by showing the missing or changed portions in
9103 the original language instead of the target language.
9108 <heading>Info documents</heading>
9111 Info documents should be installed in <file>/usr/share/info</file>.
9112 They should be compressed with <tt>gzip -9</tt>.
9116 The <prgn>install-info</prgn> program maintains a directory of
9117 installed info documents in <file>/usr/share/info/dir</file> for
9118 the use of info readers.<footnote>
9119 It was previously necessary for packages installing info
9120 documents to run <prgn>install-info</prgn> from maintainer
9121 scripts. This is no longer necessary. The installation
9122 system now uses dpkg triggers.
9124 This file must not be included in packages. Packages containing
9125 info documents should depend on <tt>dpkg (>= 1.15.4) |
9126 install-info</tt> to ensure that the directory file is properly
9127 rebuilt during partial upgrades from Debian 5.0 (lenny) and
9132 Info documents should contain section and directory entry
9133 information in the document for the use
9134 of <prgn>install-info</prgn>. The section should be specified
9135 via a line starting with <tt>INFO-DIR-SECTION</tt> followed by a
9136 space and the section of this info page. The directory entry or
9137 entries should be included between
9138 a <tt>START-INFO-DIR-ENTRY</tt> line and
9139 an <tt>END-INFO-DIR-ENTRY</tt> line. For example:
9141 INFO-DIR-SECTION Individual utilities
9142 START-INFO-DIR-ENTRY
9143 * example: (example). An example info directory entry.
9146 To determine which section to use, you should look
9147 at <file>/usr/share/info/dir</file> on your system and choose
9148 the most relevant (or create a new section if none of the
9149 current sections are relevant).<footnote>
9150 Normally, info documents are generated from Texinfo source.
9151 To include this information in the generated info document, if
9152 it is absent, add commands like:
9154 @dircategory Individual utilities
9156 * example: (example). An example info directory entry.
9159 to the Texinfo source of the document and ensure that the info
9160 documents are rebuilt from source during the package build.
9166 <heading>Additional documentation</heading>
9169 Any additional documentation that comes with the package may
9170 be installed at the discretion of the package maintainer.
9171 Plain text documentation should be installed in the directory
9172 <file>/usr/share/doc/<var>package</var></file>, where
9173 <var>package</var> is the name of the package, and
9174 compressed with <tt>gzip -9</tt> unless it is small.
9178 If a package comes with large amounts of documentation which
9179 many users of the package will not require you should create
9180 a separate binary package to contain it, so that it does not
9181 take up disk space on the machines of users who do not need
9182 or want it installed.</p>
9185 It is often a good idea to put text information files
9186 (<file>README</file>s, changelogs, and so forth) that come with
9187 the source package in <file>/usr/share/doc/<var>package</var></file>
9188 in the binary package. However, you don't need to install
9189 the instructions for building and installing the package, of
9193 Packages must not require the existence of any files in
9194 <file>/usr/share/doc/</file> in order to function
9196 The system administrator should be able to
9197 delete files in <file>/usr/share/doc/</file> without causing
9198 any programs to break.
9200 Any files that are referenced by programs but are also
9201 useful as stand alone documentation should be installed under
9202 <file>/usr/share/<var>package</var>/</file> with symbolic links from
9203 <file>/usr/share/doc/<var>package</var></file>.
9207 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9208 link to another directory in <file>/usr/share/doc</file> only if
9209 the two packages both come from the same source and the
9210 first package Depends on the second.<footnote>
9212 Please note that this does not override the section on
9213 changelog files below, so the file
9214 <file>/usr/share/doc/<var>package</var>/changelog.Debian.gz</file>
9215 must refer to the changelog for the current version of
9216 <var>package</var> in question. In practice, this means
9217 that the sources of the target and the destination of the
9218 symlink must be the same (same source package and
9225 Former Debian releases placed all additional documentation
9226 in <file>/usr/doc/<var>package</var></file>. This has been
9227 changed to <file>/usr/share/doc/<var>package</var></file>,
9228 and packages must not put documentation in the directory
9229 <file>/usr/doc/<var>package</var></file>. <footnote>
9230 At this phase of the transition, we no longer require a
9231 symbolic link in <file>/usr/doc/</file>. At a later point,
9232 policy shall change to make the symbolic links a bug.
9238 <heading>Preferred documentation formats</heading>
9241 The unification of Debian documentation is being carried out
9245 If your package comes with extensive documentation in a
9246 markup format that can be converted to various other formats
9247 you should if possible ship HTML versions in a binary
9248 package, in the directory
9249 <file>/usr/share/doc/<var>appropriate-package</var></file> or
9250 its subdirectories.<footnote>
9251 The rationale: The important thing here is that HTML
9252 docs should be available in <em>some</em> package, not
9253 necessarily in the main binary package.
9258 Other formats such as PostScript may be provided at the
9259 package maintainer's discretion.
9263 <sect id="copyrightfile">
9264 <heading>Copyright information</heading>
9267 Every package must be accompanied by a verbatim copy of its
9268 copyright information and distribution license in the file
9269 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
9270 file must neither be compressed nor be a symbolic link.
9274 In addition, the copyright file must say where the upstream
9275 sources (if any) were obtained. It should name the original
9276 authors of the package and the Debian maintainer(s) who were
9277 involved with its creation.
9281 Packages in the <em>contrib</em> or <em>non-free</em> archive
9282 areas should state in the copyright file that the package is not
9283 part of the Debian GNU/Linux distribution and briefly explain
9288 A copy of the file which will be installed in
9289 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9290 be in <file>debian/copyright</file> in the source package.
9294 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9295 link to another directory in <file>/usr/share/doc</file> only if
9296 the two packages both come from the same source and the
9297 first package Depends on the second. These rules are
9298 important because copyrights must be extractable by
9303 Packages distributed under the Apache license (version 2.0), the
9304 Artistic license, the GNU GPL (version 2 or 3), the GNU LGPL
9305 (versions 2, 2.1, or 3), and the GNU FDL (versions 1.2 or 1.3)
9306 should refer to the corresponding files
9307 under <file>/usr/share/common-licenses</file>,<footnote>
9310 <file>/usr/share/common-licenses/Apache-2.0</file>,
9311 <file>/usr/share/common-licenses/Artistic</file>,
9312 <file>/usr/share/common-licenses/GPL-2</file>,
9313 <file>/usr/share/common-licenses/GPL-3</file>,
9314 <file>/usr/share/common-licenses/LGPL-2</file>,
9315 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9316 <file>/usr/share/common-licenses/LGPL-3</file>,
9317 <file>/usr/share/common-licenses/GFDL-1.2</file>, and
9318 <file>/usr/share/common-licenses/GFDL-1.3</file>
9319 respectively. The University of California BSD license is
9320 also included in <package>base-files</package> as
9321 <file>/usr/share/common-licenses/BSD</file>, but given the
9322 brevity of this license, its specificity to code whose
9323 copyright is held by the Regents of the University of
9324 California, and the frequency of minor wording changes, its
9325 text should be included in the copyright file rather than
9326 referencing this file.
9328 </footnote> rather than quoting them in the copyright
9333 You should not use the copyright file as a general <file>README</file>
9334 file. If your package has such a file it should be
9335 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9336 <file>README.Debian</file> or some other appropriate place.</p>
9340 <heading>Examples</heading>
9343 Any examples (configurations, source files, whatever),
9344 should be installed in a directory
9345 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9346 files should not be referenced by any program: they're there
9347 for the benefit of the system administrator and users as
9348 documentation only. Architecture-specific example files
9349 should be installed in a directory
9350 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9352 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9353 latter directory itself may be a symbolic link to the
9358 If the purpose of a package is to provide examples, then the
9359 example files may be installed into
9360 <file>/usr/share/doc/<var>package</var></file>.
9364 <sect id="changelogs">
9365 <heading>Changelog files</heading>
9368 Packages that are not Debian-native must contain a
9369 compressed copy of the <file>debian/changelog</file> file from
9370 the Debian source tree in
9371 <file>/usr/share/doc/<var>package</var></file> with the name
9372 <file>changelog.Debian.gz</file>.
9376 If an upstream changelog is available, it should be accessible as
9377 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9378 plain text. If the upstream changelog is distributed in
9379 HTML, it should be made available in that form as
9380 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9381 and a plain text <file>changelog.gz</file> should be generated
9382 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9383 the upstream changelog files do not already conform to this
9384 naming convention, then this may be achieved either by
9385 renaming the files, or by adding a symbolic link, at the
9386 maintainer's discretion.<footnote>
9387 Rationale: People should not have to look in places for
9388 upstream changelogs merely because they are given
9389 different names or are distributed in HTML format.
9394 All of these files should be installed compressed using
9395 <tt>gzip -9</tt>, as they will become large with time even
9396 if they start out small.
9400 If the package has only one changelog which is used both as
9401 the Debian changelog and the upstream one because there is
9402 no separate upstream maintainer then that changelog should
9403 usually be installed as
9404 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9405 there is a separate upstream maintainer, but no upstream
9406 changelog, then the Debian changelog should still be called
9407 <file>changelog.Debian.gz</file>.
9411 For details about the format and contents of the Debian
9412 changelog file, please see <ref id="dpkgchangelog">.
9417 <appendix id="pkg-scope">
9418 <heading>Introduction and scope of these appendices</heading>
9421 These appendices are taken essentially verbatim from the
9422 now-deprecated Packaging Manual, version 3.2.1.0. They are
9423 the chapters which are likely to be of use to package
9424 maintainers and which have not already been included in the
9425 policy document itself. Most of these sections are very likely
9426 not relevant to policy; they should be treated as
9427 documentation for the packaging system. Please note that these
9428 appendices are included for convenience, and for historical
9429 reasons: they used to be part of policy package, and they have
9430 not yet been incorporated into dpkg documentation. However,
9431 they still have value, and hence they are presented here.
9435 They have not yet been checked to ensure that they are
9436 compatible with the contents of policy, and if there are any
9437 contradictions, the version in the main policy document takes
9438 precedence. The remaining chapters of the old Packaging
9439 Manual have also not been read in detail to ensure that there
9440 are not parts which have been left out. Both of these will be
9445 Certain parts of the Packaging manual were integrated into the
9446 Policy Manual proper, and removed from the appendices. Links
9447 have been placed from the old locations to the new ones.
9451 <prgn>dpkg</prgn> is a suite of programs for creating binary
9452 package files and installing and removing them on Unix
9454 <prgn>dpkg</prgn> is targeted primarily at Debian
9455 GNU/Linux, but may work on or be ported to other
9461 The binary packages are designed for the management of
9462 installed executable programs (usually compiled binaries) and
9463 their associated data, though source code examples and
9464 documentation are provided as part of some packages.</p>
9467 This manual describes the technical aspects of creating Debian
9468 binary packages (<file>.deb</file> files). It documents the
9469 behavior of the package management programs
9470 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9471 they interact with packages.</p>
9474 It also documents the interaction between
9475 <prgn>dselect</prgn>'s core and the access method scripts it
9476 uses to actually install the selected packages, and describes
9477 how to create a new access method.</p>
9480 This manual does not go into detail about the options and
9481 usage of the package building and installation tools. It
9482 should therefore be read in conjunction with those programs'
9487 The utility programs which are provided with <prgn>dpkg</prgn>
9488 for managing various system configuration and similar issues,
9489 such as <prgn>update-rc.d</prgn> and
9490 <prgn>install-info</prgn>, are not described in detail here -
9491 please see their man pages.
9495 It is assumed that the reader is reasonably familiar with the
9496 <prgn>dpkg</prgn> System Administrators' manual.
9497 Unfortunately this manual does not yet exist.
9501 The Debian version of the FSF's GNU hello program is provided
9502 as an example for people wishing to create Debian
9503 packages. The Debian <prgn>debmake</prgn> package is
9504 recommended as a very helpful tool in creating and maintaining
9505 Debian packages. However, while the tools and examples are
9506 helpful, they do not replace the need to read and follow the
9507 Policy and Programmer's Manual.</p>
9510 <appendix id="pkg-binarypkg">
9511 <heading>Binary packages (from old Packaging Manual)</heading>
9514 The binary package has two main sections. The first part
9515 consists of various control information files and scripts used
9516 by <prgn>dpkg</prgn> when installing and removing. See <ref
9517 id="pkg-controlarea">.
9521 The second part is an archive containing the files and
9522 directories to be installed.
9526 In the future binary packages may also contain other
9527 components, such as checksums and digital signatures. The
9528 format for the archive is described in full in the
9529 <file>deb(5)</file> man page.
9533 <sect id="pkg-bincreating"><heading>Creating package files -
9534 <prgn>dpkg-deb</prgn>
9538 All manipulation of binary package files is done by
9539 <prgn>dpkg-deb</prgn>; it's the only program that has
9540 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9541 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9542 will spot that the options requested are appropriate to
9543 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9548 In order to create a binary package you must make a
9549 directory tree which contains all the files and directories
9550 you want to have in the file system data part of the package.
9551 In Debian-format source packages this directory is usually
9552 <file>debian/tmp</file>, relative to the top of the package's
9557 They should have the locations (relative to the root of the
9558 directory tree you're constructing) ownerships and
9559 permissions which you want them to have on the system when
9564 With current versions of <prgn>dpkg</prgn> the uid/username
9565 and gid/groupname mappings for the users and groups being
9566 used should be the same on the system where the package is
9567 built and the one where it is installed.
9571 You need to add one special directory to the root of the
9572 miniature file system tree you're creating:
9573 <prgn>DEBIAN</prgn>. It should contain the control
9574 information files, notably the binary package control file
9575 (see <ref id="pkg-controlfile">).
9579 The <prgn>DEBIAN</prgn> directory will not appear in the
9580 file system archive of the package, and so won't be installed
9581 by <prgn>dpkg</prgn> when the package is installed.
9585 When you've prepared the package, you should invoke:
9587 dpkg --build <var>directory</var>
9592 This will build the package in
9593 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9594 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9595 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9600 See the man page <manref name="dpkg-deb" section="8"> for details of how
9601 to examine the contents of this newly-created file. You may find the
9602 output of following commands enlightening:
9604 dpkg-deb --info <var>filename</var>.deb
9605 dpkg-deb --contents <var>filename</var>.deb
9606 dpkg --contents <var>filename</var>.deb
9608 To view the copyright file for a package you could use this command:
9610 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
9615 <sect id="pkg-controlarea">
9616 <heading>Package control information files</heading>
9619 The control information portion of a binary package is a
9620 collection of files with names known to <prgn>dpkg</prgn>.
9621 It will treat the contents of these files specially - some
9622 of them contain information used by <prgn>dpkg</prgn> when
9623 installing or removing the package; others are scripts which
9624 the package maintainer wants <prgn>dpkg</prgn> to run.
9628 It is possible to put other files in the package control
9629 area, but this is not generally a good idea (though they
9630 will largely be ignored).
9634 Here is a brief list of the control info files supported by
9635 <prgn>dpkg</prgn> and a summary of what they're used for.
9640 <tag><tt>control</tt>
9643 This is the key description file used by
9644 <prgn>dpkg</prgn>. It specifies the package's name
9645 and version, gives its description for the user,
9646 states its relationships with other packages, and so
9647 forth. See <ref id="sourcecontrolfiles"> and
9648 <ref id="binarycontrolfiles">.
9652 It is usually generated automatically from information
9653 in the source package by the
9654 <prgn>dpkg-gencontrol</prgn> program, and with
9655 assistance from <prgn>dpkg-shlibdeps</prgn>.
9656 See <ref id="pkg-sourcetools">.
9660 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9665 These are executable files (usually scripts) which
9666 <prgn>dpkg</prgn> runs during installation, upgrade
9667 and removal of packages. They allow the package to
9668 deal with matters which are particular to that package
9669 or require more complicated processing than that
9670 provided by <prgn>dpkg</prgn>. Details of when and
9671 how they are called are in <ref id="maintainerscripts">.
9675 It is very important to make these scripts idempotent.
9676 See <ref id="idempotency">.
9680 The maintainer scripts are not guaranteed to run with a
9681 controlling terminal and may not be able to interact with
9682 the user. See <ref id="controllingterminal">.
9686 <tag><tt>conffiles</tt>
9689 This file contains a list of configuration files which
9690 are to be handled automatically by <prgn>dpkg</prgn>
9691 (see <ref id="pkg-conffiles">). Note that not necessarily
9692 every configuration file should be listed here.
9695 <tag><tt>shlibs</tt>
9698 This file contains a list of the shared libraries
9699 supplied by the package, with dependency details for
9700 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9701 when it determines what dependencies are required in a
9702 package control file. The <tt>shlibs</tt> file format
9703 is described on <ref id="shlibs">.
9708 <sect id="pkg-controlfile">
9709 <heading>The main control information file: <tt>control</tt></heading>
9712 The most important control information file used by
9713 <prgn>dpkg</prgn> when it installs a package is
9714 <tt>control</tt>. It contains all the package's "vital
9719 The binary package control files of packages built from
9720 Debian sources are made by a special tool,
9721 <prgn>dpkg-gencontrol</prgn>, which reads
9722 <file>debian/control</file> and <file>debian/changelog</file> to
9723 find the information it needs. See <ref id="pkg-sourcepkg"> for
9728 The fields in binary package control files are listed in
9729 <ref id="binarycontrolfiles">.
9733 A description of the syntax of control files and the purpose
9734 of the fields is available in <ref id="controlfields">.
9739 <heading>Time Stamps</heading>
9742 See <ref id="timestamps">.
9747 <appendix id="pkg-sourcepkg">
9748 <heading>Source packages (from old Packaging Manual) </heading>
9751 The Debian binary packages in the distribution are generated
9752 from Debian sources, which are in a special format to assist
9753 the easy and automatic building of binaries.
9756 <sect id="pkg-sourcetools">
9757 <heading>Tools for processing source packages</heading>
9760 Various tools are provided for manipulating source packages;
9761 they pack and unpack sources and help build of binary
9762 packages and help manage the distribution of new versions.
9766 They are introduced and typical uses described here; see
9767 <manref name="dpkg-source" section="1"> for full
9768 documentation about their arguments and operation.
9772 For examples of how to construct a Debian source package,
9773 and how to use those utilities that are used by Debian
9774 source packages, please see the <prgn>hello</prgn> example
9778 <sect1 id="pkg-dpkg-source">
9780 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
9785 This program is frequently used by hand, and is also
9786 called from package-independent automated building scripts
9787 such as <prgn>dpkg-buildpackage</prgn>.
9791 To unpack a package it is typically invoked with
9793 dpkg-source -x <var>.../path/to/filename</var>.dsc
9798 with the <file><var>filename</var>.tar.gz</file> and
9799 <file><var>filename</var>.diff.gz</file> (if applicable) in
9800 the same directory. It unpacks into
9801 <file><var>package</var>-<var>version</var></file>, and if
9803 <file><var>package</var>-<var>version</var>.orig</file>, in
9804 the current directory.
9808 To create a packed source archive it is typically invoked:
9810 dpkg-source -b <var>package</var>-<var>version</var>
9815 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
9816 <file>.diff.gz</file> (if appropriate) in the current
9817 directory. <prgn>dpkg-source</prgn> does not clean the
9818 source tree first - this must be done separately if it is
9823 See also <ref id="pkg-sourcearchives">.</p>
9827 <sect1 id="pkg-dpkg-buildpackage">
9829 <prgn>dpkg-buildpackage</prgn> - overall package-building
9834 <prgn>dpkg-buildpackage</prgn> is a script which invokes
9835 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
9836 targets <tt>clean</tt>, <tt>build</tt> and
9837 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
9838 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
9839 source and binary package upload.
9843 It is usually invoked by hand from the top level of the
9844 built or unbuilt source directory. It may be invoked with
9845 no arguments; useful arguments include:
9846 <taglist compact="compact">
9847 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
9850 Do not sign the <tt>.changes</tt> file or the
9851 source package <tt>.dsc</tt> file, respectively.</p>
9853 <tag><tt>-p<var>sign-command</var></tt></tag>
9856 Invoke <var>sign-command</var> instead of finding
9857 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
9858 <var>sign-command</var> must behave just like
9859 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9861 <tag><tt>-r<var>root-command</var></tt></tag>
9864 When root privilege is required, invoke the command
9865 <var>root-command</var>. <var>root-command</var>
9866 should invoke its first argument as a command, from
9867 the <prgn>PATH</prgn> if necessary, and pass its
9868 second and subsequent arguments to the command it
9869 calls. If no <var>root-command</var> is supplied
9870 then <var>dpkg-buildpackage</var> will take no
9871 special action to gain root privilege, so that for
9872 most packages it will have to be invoked as root to
9875 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9878 Two types of binary-only build and upload - see
9879 <manref name="dpkg-source" section="1">.
9886 <sect1 id="pkg-dpkg-gencontrol">
9888 <prgn>dpkg-gencontrol</prgn> - generates binary package
9893 This program is usually called from <file>debian/rules</file>
9894 (see <ref id="pkg-sourcetree">) in the top level of the source
9899 This is usually done just before the files and directories in the
9900 temporary directory tree where the package is being built have their
9901 permissions and ownerships set and the package is constructed using
9902 <prgn>dpkg-deb/</prgn>
9904 This is so that the control file which is produced has
9905 the right permissions
9910 <prgn>dpkg-gencontrol</prgn> must be called after all the
9911 files which are to go into the package have been placed in
9912 the temporary build directory, so that its calculation of
9913 the installed size of a package is correct.
9917 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9918 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9919 variable substitutions created by
9920 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9925 For a package which generates only one binary package, and
9926 which builds it in <file>debian/tmp</file> relative to the top
9927 of the source package, it is usually sufficient to call
9928 <prgn>dpkg-gencontrol</prgn>.
9932 Sources which build several binaries will typically need
9935 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9936 </example> The <tt>-P</tt> tells
9937 <prgn>dpkg-gencontrol</prgn> that the package is being
9938 built in a non-default directory, and the <tt>-p</tt>
9939 tells it which package's control file should be generated.
9943 <prgn>dpkg-gencontrol</prgn> also adds information to the
9944 list of files in <file>debian/files</file>, for the benefit of
9945 (for example) a future invocation of
9946 <prgn>dpkg-genchanges</prgn>.</p>
9949 <sect1 id="pkg-dpkg-shlibdeps">
9951 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9956 This program is usually called from <file>debian/rules</file>
9957 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9958 id="pkg-sourcetree">), in the top level of the source tree.
9962 Its arguments are executables and shared libraries
9965 They may be specified either in the locations in the
9966 source tree where they are created or in the locations
9967 in the temporary build tree where they are installed
9968 prior to binary package creation.
9970 </footnote> for which shared library dependencies should
9971 be included in the binary package's control file.
9975 If some of the found shared libraries should only
9976 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9977 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9978 by using the <tt>-d<var>dependency-field</var></tt> option
9979 before those executable(s). (Each <tt>-d</tt> option
9980 takes effect until the next <tt>-d</tt>.)
9984 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9985 output control file to be modified. Instead by default it
9986 adds to the <file>debian/substvars</file> file variable
9987 settings like <tt>shlibs:Depends</tt>. These variable
9988 settings must be referenced in dependency fields in the
9989 appropriate per-binary-package sections of the source
9994 For example, a package that generates an essential part
9995 which requires dependencies, and optional parts that
9996 which only require a recommendation, would separate those
9997 two sets of dependencies into two different fields.<footnote>
9998 At the time of writing, an example for this was the
9999 <package/xmms/ package, with Depends used for the xmms
10000 executable, Recommends for the plug-ins and Suggests for
10001 even more optional features provided by unzip.
10003 It can say in its <file>debian/rules</file>:
10005 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
10006 -dRecommends <var>optionalpart anotheroptionalpart</var>
10008 and then in its main control file <file>debian/control</file>:
10011 Depends: ${shlibs:Depends}
10012 Recommends: ${shlibs:Recommends}
10018 Sources which produce several binary packages with
10019 different shared library dependency requirements can use
10020 the <tt>-p<var>varnameprefix</var></tt> option to override
10021 the default <tt>shlibs:</tt> prefix (one invocation of
10022 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
10023 They can thus produce several sets of dependency
10024 variables, each of the form
10025 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
10026 which can be referred to in the appropriate parts of the
10027 binary package control files.
10032 <sect1 id="pkg-dpkg-distaddfile">
10034 <prgn>dpkg-distaddfile</prgn> - adds a file to
10035 <file>debian/files</file>
10039 Some packages' uploads need to include files other than
10040 the source and binary package files.
10044 <prgn>dpkg-distaddfile</prgn> adds a file to the
10045 <file>debian/files</file> file so that it will be included in
10046 the <file>.changes</file> file when
10047 <prgn>dpkg-genchanges</prgn> is run.
10051 It is usually invoked from the <tt>binary</tt> target of
10052 <file>debian/rules</file>:
10054 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
10056 The <var>filename</var> is relative to the directory where
10057 <prgn>dpkg-genchanges</prgn> will expect to find it - this
10058 is usually the directory above the top level of the source
10059 tree. The <file>debian/rules</file> target should put the
10060 file there just before or just after calling
10061 <prgn>dpkg-distaddfile</prgn>.
10065 The <var>section</var> and <var>priority</var> are passed
10066 unchanged into the resulting <file>.changes</file> file.
10071 <sect1 id="pkg-dpkg-genchanges">
10073 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
10074 upload control file
10078 This program is usually called by package-independent
10079 automatic building scripts such as
10080 <prgn>dpkg-buildpackage</prgn>, but it may also be called
10085 It is usually called in the top level of a built source
10086 tree, and when invoked with no arguments will print out a
10087 straightforward <file>.changes</file> file based on the
10088 information in the source package's changelog and control
10089 file and the binary and source packages which should have
10095 <sect1 id="pkg-dpkg-parsechangelog">
10097 <prgn>dpkg-parsechangelog</prgn> - produces parsed
10098 representation of a changelog
10102 This program is used internally by
10103 <prgn>dpkg-source</prgn> et al. It may also occasionally
10104 be useful in <file>debian/rules</file> and elsewhere. It
10105 parses a changelog, <file>debian/changelog</file> by default,
10106 and prints a control-file format representation of the
10107 information in it to standard output.
10111 <sect1 id="pkg-dpkg-architecture">
10113 <prgn>dpkg-architecture</prgn> - information about the build and
10118 This program can be used manually, but is also invoked by
10119 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
10120 environment or make variables which specify the build and host
10121 architecture for the package building process.
10126 <sect id="pkg-sourcetree">
10127 <heading>The Debianised source tree</heading>
10130 The source archive scheme described later is intended to
10131 allow a Debianised source tree with some associated control
10132 information to be reproduced and transported easily. The
10133 Debianised source tree is a version of the original program
10134 with certain files added for the benefit of the
10135 Debianisation process, and with any other changes required
10136 made to the rest of the source code and installation
10141 The extra files created for Debian are in the subdirectory
10142 <file>debian</file> of the top level of the Debianised source
10143 tree. They are described below.
10146 <sect1 id="pkg-debianrules">
10147 <heading><file>debian/rules</file> - the main building script</heading>
10150 See <ref id="debianrules">.
10154 <sect1 id="pkg-srcsubstvars">
10155 <heading><file>debian/substvars</file> and variable substitutions</heading>
10158 See <ref id="substvars">.
10164 <heading><file>debian/files</file></heading>
10167 See <ref id="debianfiles">.
10171 <sect1><heading><file>debian/tmp</file>
10175 This is the canonical temporary location for the
10176 construction of binary packages by the <tt>binary</tt>
10177 target. The directory <file>tmp</file> serves as the root of
10178 the file system tree as it is being constructed (for
10179 example, by using the package's upstream makefiles install
10180 targets and redirecting the output there), and it also
10181 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10182 id="pkg-bincreating">.
10186 If several binary packages are generated from the same
10187 source tree it is usual to use several
10188 <file>debian/tmp<var>something</var></file> directories, for
10189 example <file>tmp-a</file> or <file>tmp-doc</file>.
10193 Whatever <file>tmp</file> directories are created and used by
10194 <tt>binary</tt> must of course be removed by the
10195 <tt>clean</tt> target.</p></sect1>
10199 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10203 As it exists on the FTP site, a Debian source package
10204 consists of three related files. You must have the right
10205 versions of all three to be able to use them.
10210 <tag>Debian source control file - <tt>.dsc</tt></tag>
10212 This file is a control file used by <prgn>dpkg-source</prgn>
10213 to extract a source package.
10214 See <ref id="debiansourcecontrolfiles">.
10218 Original source archive -
10220 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10226 This is a compressed (with <tt>gzip -9</tt>)
10227 <prgn>tar</prgn> file containing the source code from
10228 the upstream authors of the program.
10233 Debianisation diff -
10235 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10241 This is a unified context diff (<tt>diff -u</tt>)
10242 giving the changes which are required to turn the
10243 original source into the Debian source. These changes
10244 may only include editing and creating plain files.
10245 The permissions of files, the targets of symbolic
10246 links and the characteristics of special files or
10247 pipes may not be changed and no files may be removed
10252 All the directories in the diff must exist, except the
10253 <file>debian</file> subdirectory of the top of the source
10254 tree, which will be created by
10255 <prgn>dpkg-source</prgn> if necessary when unpacking.
10259 The <prgn>dpkg-source</prgn> program will
10260 automatically make the <file>debian/rules</file> file
10261 executable (see below).</p></item>
10266 If there is no original source code - for example, if the
10267 package is specially prepared for Debian or the Debian
10268 maintainer is the same as the upstream maintainer - the
10269 format is slightly different: then there is no diff, and the
10271 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10272 and preferably contains a directory named
10273 <file><var>package</var>-<var>version</var></file>.
10278 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10281 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10282 Debian source package. However, if it is not available it
10283 is possible to unpack a Debian source archive as follows:
10284 <enumlist compact="compact">
10287 Untar the tarfile, which will create a <file>.orig</file>
10291 <p>Rename the <file>.orig</file> directory to
10292 <file><var>package</var>-<var>version</var></file>.</p>
10296 Create the subdirectory <file>debian</file> at the top of
10297 the source tree.</p>
10299 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10301 <item><p>Untar the tarfile again if you want a copy of the original
10302 source code alongside the Debianised version.</p>
10307 It is not possible to generate a valid Debian source archive
10308 without using <prgn>dpkg-source</prgn>. In particular,
10309 attempting to use <prgn>diff</prgn> directly to generate the
10310 <file>.diff.gz</file> file will not work.
10314 <heading>Restrictions on objects in source packages</heading>
10317 The source package may not contain any hard links
10319 This is not currently detected when building source
10320 packages, but only when extracting
10324 Hard links may be permitted at some point in the
10325 future, but would require a fair amount of
10327 </footnote>, device special files, sockets or setuid or
10330 Setgid directories are allowed.
10335 The source packaging tools manage the changes between the
10336 original and Debianised source using <prgn>diff</prgn> and
10337 <prgn>patch</prgn>. Turning the original source tree as
10338 included in the <file>.orig.tar.gz</file> into the debianised
10339 source must not involve any changes which cannot be
10340 handled by these tools. Problematic changes which cause
10341 <prgn>dpkg-source</prgn> to halt with an error when
10342 building the source package are:
10343 <list compact="compact">
10344 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10346 <item><p>Changing the targets of symbolic links.</p>
10348 <item><p>Creating directories, other than <file>debian</file>.</p>
10350 <item><p>Changes to the contents of binary files.</p></item>
10351 </list> Changes which cause <prgn>dpkg-source</prgn> to
10352 print a warning but continue anyway are:
10353 <list compact="compact">
10356 Removing files, directories or symlinks.
10358 Renaming a file is not treated specially - it is
10359 seen as the removal of the old file (which
10360 generates a warning, but is otherwise ignored),
10361 and the creation of the new one.
10367 Changed text files which are missing the usual final
10368 newline (either in the original or the modified
10373 Changes which are not represented, but which are not detected by
10374 <prgn>dpkg-source</prgn>, are:
10375 <list compact="compact">
10376 <item><p>Changing the permissions of files (other than
10377 <file>debian/rules</file>) and directories.</p></item>
10382 The <file>debian</file> directory and <file>debian/rules</file>
10383 are handled specially by <prgn>dpkg-source</prgn> - before
10384 applying the changes it will create the <file>debian</file>
10385 directory, and afterwards it will make
10386 <file>debian/rules</file> world-executable.
10392 <appendix id="pkg-controlfields">
10393 <heading>Control files and their fields (from old Packaging Manual)</heading>
10396 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10397 data in a common format, known as control files. Binary and
10398 source packages have control data as do the <file>.changes</file>
10399 files which control the installation of uploaded files, and
10400 <prgn>dpkg</prgn>'s internal databases are in a similar
10405 <heading>Syntax of control files</heading>
10408 See <ref id="controlsyntax">.
10412 It is important to note that there are several fields which
10413 are optional as far as <prgn>dpkg</prgn> and the related
10414 tools are concerned, but which must appear in every Debian
10415 package, or whose omission may cause problems.
10420 <heading>List of fields</heading>
10423 See <ref id="controlfieldslist">.
10427 This section now contains only the fields that didn't belong
10428 to the Policy manual.
10431 <sect1 id="pkg-f-Filename">
10432 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10435 These fields in <tt>Packages</tt> files give the
10436 filename(s) of (the parts of) a package in the
10437 distribution directories, relative to the root of the
10438 Debian hierarchy. If the package has been split into
10439 several parts the parts are all listed in order, separated
10444 <sect1 id="pkg-f-Size">
10445 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10448 These fields in <file>Packages</file> files give the size (in
10449 bytes, expressed in decimal) and MD5 checksum of the
10450 file(s) which make(s) up a binary package in the
10451 distribution. If the package is split into several parts
10452 the values for the parts are listed in order, separated by
10457 <sect1 id="pkg-f-Status">
10458 <heading><tt>Status</tt></heading>
10461 This field in <prgn>dpkg</prgn>'s status file records
10462 whether the user wants a package installed, removed or
10463 left alone, whether it is broken (requiring
10464 re-installation) or not and what its current state on the
10465 system is. Each of these pieces of information is a
10470 <sect1 id="pkg-f-Config-Version">
10471 <heading><tt>Config-Version</tt></heading>
10474 If a package is not installed or not configured, this
10475 field in <prgn>dpkg</prgn>'s status file records the last
10476 version of the package which was successfully
10481 <sect1 id="pkg-f-Conffiles">
10482 <heading><tt>Conffiles</tt></heading>
10485 This field in <prgn>dpkg</prgn>'s status file contains
10486 information about the automatically-managed configuration
10487 files held by a package. This field should <em>not</em>
10488 appear anywhere in a package!
10493 <heading>Obsolete fields</heading>
10496 These are still recognized by <prgn>dpkg</prgn> but should
10497 not appear anywhere any more.
10499 <taglist compact="compact">
10501 <tag><tt>Revision</tt></tag>
10502 <tag><tt>Package-Revision</tt></tag>
10503 <tag><tt>Package_Revision</tt></tag>
10505 The Debian revision part of the package version was
10506 at one point in a separate control file field. This
10507 field went through several names.
10510 <tag><tt>Recommended</tt></tag>
10511 <item>Old name for <tt>Recommends</tt>.</item>
10513 <tag><tt>Optional</tt></tag>
10514 <item>Old name for <tt>Suggests</tt>.</item>
10516 <tag><tt>Class</tt></tag>
10517 <item>Old name for <tt>Priority</tt>.</item>
10526 <appendix id="pkg-conffiles">
10527 <heading>Configuration file handling (from old Packaging Manual)</heading>
10530 <prgn>dpkg</prgn> can do a certain amount of automatic
10531 handling of package configuration files.
10535 Whether this mechanism is appropriate depends on a number of
10536 factors, but basically there are two approaches to any
10537 particular configuration file.
10541 The easy method is to ship a best-effort configuration in the
10542 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10543 handle updates. If the user is unlikely to want to edit the
10544 file, but you need them to be able to without losing their
10545 changes, and a new package with a changed version of the file
10546 is only released infrequently, this is a good approach.
10550 The hard method is to build the configuration file from
10551 scratch in the <prgn>postinst</prgn> script, and to take the
10552 responsibility for fixing any mistakes made in earlier
10553 versions of the package automatically. This will be
10554 appropriate if the file is likely to need to be different on
10558 <sect><heading>Automatic handling of configuration files by
10563 A package may contain a control area file called
10564 <tt>conffiles</tt>. This file should be a list of filenames
10565 of configuration files needing automatic handling, separated
10566 by newlines. The filenames should be absolute pathnames,
10567 and the files referred to should actually exist in the
10572 When a package is upgraded <prgn>dpkg</prgn> will process
10573 the configuration files during the configuration stage,
10574 shortly before it runs the package's <prgn>postinst</prgn>
10579 For each file it checks to see whether the version of the
10580 file included in the package is the same as the one that was
10581 included in the last version of the package (the one that is
10582 being upgraded from); it also compares the version currently
10583 installed on the system with the one shipped with the last
10588 If neither the user nor the package maintainer has changed
10589 the file, it is left alone. If one or the other has changed
10590 their version, then the changed version is preferred - i.e.,
10591 if the user edits their file, but the package maintainer
10592 doesn't ship a different version, the user's changes will
10593 stay, silently, but if the maintainer ships a new version
10594 and the user hasn't edited it the new version will be
10595 installed (with an informative message). If both have
10596 changed their version the user is prompted about the problem
10597 and must resolve the differences themselves.
10601 The comparisons are done by calculating the MD5 message
10602 digests of the files, and storing the MD5 of the file as it
10603 was included in the most recent version of the package.
10607 When a package is installed for the first time
10608 <prgn>dpkg</prgn> will install the file that comes with it,
10609 unless that would mean overwriting a file already on the
10614 However, note that <prgn>dpkg</prgn> will <em>not</em>
10615 replace a conffile that was removed by the user (or by a
10616 script). This is necessary because with some programs a
10617 missing file produces an effect hard or impossible to
10618 achieve in another way, so that a missing file needs to be
10619 kept that way if the user did it.
10623 Note that a package should <em>not</em> modify a
10624 <prgn>dpkg</prgn>-handled conffile in its maintainer
10625 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10626 the user confusing and possibly dangerous options for
10627 conffile update when the package is upgraded.</p>
10630 <sect><heading>Fully-featured maintainer script configuration
10635 For files which contain site-specific information such as
10636 the hostname and networking details and so forth, it is
10637 better to create the file in the package's
10638 <prgn>postinst</prgn> script.
10642 This will typically involve examining the state of the rest
10643 of the system to determine values and other information, and
10644 may involve prompting the user for some information which
10645 can't be obtained some other way.
10649 When using this method there are a couple of important
10650 issues which should be considered:
10654 If you discover a bug in the program which generates the
10655 configuration file, or if the format of the file changes
10656 from one version to the next, you will have to arrange for
10657 the postinst script to do something sensible - usually this
10658 will mean editing the installed configuration file to remove
10659 the problem or change the syntax. You will have to do this
10660 very carefully, since the user may have changed the file,
10661 perhaps to fix the very problem that your script is trying
10662 to deal with - you will have to detect these situations and
10663 deal with them correctly.
10667 If you do go down this route it's probably a good idea to
10668 make the program that generates the configuration file(s) a
10669 separate program in <file>/usr/sbin</file>, by convention called
10670 <file><var>package</var>config</file> and then run that if
10671 appropriate from the post-installation script. The
10672 <tt><var>package</var>config</tt> program should not
10673 unquestioningly overwrite an existing configuration - if its
10674 mode of operation is geared towards setting up a package for
10675 the first time (rather than any arbitrary reconfiguration
10676 later) you should have it check whether the configuration
10677 already exists, and require a <tt>--force</tt> flag to
10678 overwrite it.</p></sect>
10681 <appendix id="pkg-alternatives"><heading>Alternative versions of
10682 an interface - <prgn>update-alternatives</prgn> (from old
10687 When several packages all provide different versions of the
10688 same program or file it is useful to have the system select a
10689 default, but to allow the system administrator to change it
10690 and have their decisions respected.
10694 For example, there are several versions of the <prgn>vi</prgn>
10695 editor, and there is no reason to prevent all of them from
10696 being installed at once, each under their own name
10697 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10698 Nevertheless it is desirable to have the name <tt>vi</tt>
10699 refer to something, at least by default.
10703 If all the packages involved cooperate, this can be done with
10704 <prgn>update-alternatives</prgn>.
10708 Each package provides its own version under its own name, and
10709 calls <prgn>update-alternatives</prgn> in its postinst to
10710 register its version (and again in its prerm to deregister
10715 See the man page <manref name="update-alternatives"
10716 section="8"> for details.
10720 If <prgn>update-alternatives</prgn> does not seem appropriate
10721 you may wish to consider using diversions instead.</p>
10724 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10725 package's version of a file (from old Packaging Manual)
10729 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10730 when it reinstalls the package it belongs to, and to have it
10731 put the file from the package somewhere else instead.
10735 This can be used locally to override a package's version of a
10736 file, or by one package to override another's version (or
10737 provide a wrapper for it).
10741 Before deciding to use a diversion, read <ref
10742 id="pkg-alternatives"> to see if you really want a diversion
10743 rather than several alternative versions of a program.
10747 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10748 and updated by a special program <prgn>dpkg-divert</prgn>.
10749 Please see <manref name="dpkg-divert" section="8"> for full
10750 details of its operation.
10754 When a package wishes to divert a file from another, it should
10755 call <prgn>dpkg-divert</prgn> in its preinst to add the
10756 diversion and rename the existing file. For example,
10757 supposing that a <prgn>smailwrapper</prgn> package wishes to
10758 install a wrapper around <file>/usr/sbin/smail</file>:
10760 dpkg-divert --package smailwrapper --add --rename \
10761 --divert /usr/sbin/smail.real /usr/sbin/smail
10762 </example> The <tt>--package smailwrapper</tt> ensures that
10763 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
10764 can bypass the diversion and get installed as the true version.
10765 It's safe to add the diversion unconditionally on upgrades since
10766 it will be left unchanged if it already exists, but
10767 <prgn>dpkg-divert</prgn> will display a message. To suppress that
10768 message, make the command conditional on the version from which
10769 the package is being upgraded:
10771 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
10772 dpkg-divert --package smailwrapper --add --rename \
10773 --divert /usr/sbin/smail.real /usr/sbin/smail
10775 </example> where <tt>1.0-2</tt> is the version at which the
10776 diversion was first added to the package. Running the command
10777 during abort-upgrade is pointless but harmless.
10781 The postrm has to do the reverse:
10783 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
10784 dpkg-divert --package smailwrapper --remove --rename \
10785 --divert /usr/sbin/smail.real /usr/sbin/smail
10787 </example> If the diversion was added at a particular version, the
10788 postrm should also handle the failure case of upgrading from an
10789 older version (unless the older version is so old that direct
10790 upgrades are no longer supported):
10792 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
10793 dpkg-divert --package smailwrapper --remove --rename \
10794 --divert /usr/sbin/smail.real /usr/sbin/smail
10796 </example> where <tt>1.02-2</tt> is the version at which the
10797 diversion was first added to the package. The postrm should not
10798 remove the diversion on upgrades both because there's no reason to
10799 remove the diversion only to immediately re-add it and since the
10800 postrm of the old package is run after unpacking so the removal of
10801 the diversion will fail.
10805 Do not attempt to divert a file which is vitally important for
10806 the system's operation - when using <prgn>dpkg-divert</prgn>
10807 there is a time, after it has been diverted but before
10808 <prgn>dpkg</prgn> has installed the new version, when the file
10809 does not exist.</p>
10814 <!-- Local variables: -->
10815 <!-- indent-tabs-mode: t -->
10817 <!-- vim:set ai et sts=2 sw=2 tw=76: -->