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8 Debian GNU/Linux Policy Manual.
9 Copyright (C)1996,1997,1998 Ian Jackson and Christian Schwarz;
10 released under the terms of the GNU
11 General Public License, version 2 or (at your option) any later.
12 Initial version 1996, Ian Jackson, ijackson@gnu.ai.mit.edu
13 Revised November 27, 1996, David A. Morris, bweaver@debian.org
14 New sections March 15, 1997, Christian Schwarz, schwarz@debian.org
15 Reworked/Restructured April-July 1997, Christian Schwarz, schwarz@debian.org
16 Maintainer since 1997, Christian Schwarz, schwarz@debian.org
17 Christoph Lameter contributed the "Web Standard"
18 The debian-policy mailing list has taken responsibility for the
19 contents of this document since September 1998, with the package
20 maintainers responsible for packaging administrivia only.
25 <title>Debian Policy Manual</title>
27 <name>Ian Jackson </name>
28 <email>ijackson@gnu.ai.mit.edu</email>
31 <name>Christian Schwarz</name>
32 <email>schwarz@debian.org</email>
35 <name>revised: David A. Morris</name>
36 <email>bweaver@debian.org</email>
39 <name>The Debian Policy mailing List</name>
40 <email>debian-policy@lists.debian.org</email>
42 <version>version &version;, &date;</version>
45 This manual describes the policy requirements for the Debian
46 GNU/Linux distribution. This includes the structure and
47 contents of the Debian archive and several design issues of the
48 operating system, as well as technical requirements that each
49 package must satisfy to be included in the distribution. The
50 policy package itself is maintained by a group of maintainers
51 that have no editorial powers. At the moment, the list of
55 <p>Julian Gilbey <email>jdg@debian.org</email></p>
58 <p>Manoj Srivastava <email>srivasta@debian.org</email></p>
66 Copyright ©1996,1997,1998 Ian Jackson
67 and Christian Schwarz.
70 This manual is free software; you may redistribute it and/or
71 modify it under the terms of the GNU General Public License
72 as published by the Free Software Foundation; either version
73 2, or (at your option) any later version.
77 This is distributed in the hope that it will be useful, but
78 <em>without any warranty</em>; without even the implied
79 warranty of merchantability or fitness for a particular
80 purpose. See the GNU General Public License for more
85 A copy of the GNU General Public License is available as
86 <tt>/usr/share/common-licenses/GPL</tt> in the Debian GNU/Linux
87 distribution or on the World Wide Web at
88 <url id="http://www.gnu.org/copyleft/gpl.html"
89 name="The GNU General Public Licence">. You can also
90 obtain it by writing to the Free Software Foundation, Inc.,
91 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
99 <heading>About this manual</heading>
101 <heading>Scope</heading>
103 This manual describes the policy requirements for the Debian
104 GNU/Linux distribution. This includes the structure and
105 contents of the Debian archive and several design issues of the
106 operating system, as well as technical requirements that
107 each package must satisfy to be included in the
113 This manual also describes Debian policy as it relates to
114 creating Debian packages. It is not a tutorial on how to build
115 packages, nor is it exhaustive where it comes to describing
116 the behavior of the packaging system. Instead, this manual
117 attempts to define the interface to the package management
118 system that the developers have to be conversant with.
121 Informally, the criteria used for inclusion is that the
122 material meet one of the following requirements:
124 <tag>Standard interfaces</tag>
127 The material presented represents an interface to
128 the packaging system that is mandated for use, and
129 is used by, a significant number of packages, and
130 therefore should not be changed without peer
131 review. Package maintainers can then rely on this
132 interfaces not changing, and the package
133 management software authors need to ensure
134 compatibility with these interface
135 definitions. (Control file and changelog file
136 formats are examples.)
139 <tag>Chosen Convention</tag>
142 If there are a number of technically viable choices
143 that can be made, but one needs to select one of
144 these options for inter-operability. The version
145 number format is one example.
149 Please note that these are not mutually exclusive;
150 selected conventions often become parts of standard
157 The footnotes present in this manual are
158 merely informative, and are not part of Debian policy itself.
163 In this manual, the words <em>must</em>, <em>should</em> and
164 <em>may</em>, and the adjectives <em>required</em>,
165 <em>recommended</em> and <em>optional</em>, are used to
166 distinguish the significance of the various guidelines in
167 this policy document. Packages that do not conform to the
168 guidelines denoted by <em>must</em> (or <em>required</em>)
169 will generally not be considered acceptable for the Debian
170 distribution. Non-conformance with guidelines denoted by
171 <em>should</em> (or <em>recommended</em>) will generally be
172 considered a bug, but will not necessarily render a package
173 unsuitable for distribution. Guidelines denoted by
174 <em>may</em> (or <em>optional</em>) are truly optional and
175 adherence is left to the maintainer's discretion.
178 These classifications are roughly equivalent to the bug
179 severities <em>serious</em> (for <em>must</em> or
180 <em>required</em> directive violations), <em>minor</em>,
181 <em>normal</em> or <em>important</em>
182 (for <em>should</em> or <em>recommended</em> directive
183 violations) and <em>wishlist</em> (for <em>optional</em>
185 <p>Compare RFC 2119. Note, however, that these words are
186 used in a different way in this document.</p>
190 Much of the information presented in this manual will be
191 useful even when building a package which is to be
192 distributed in some other way or is intended for local use
197 <heading>New versions of this document</heading>
199 The current version of this document is always accessible
200 from the Debian FTP server <ftpsite>ftp.debian.org</ftpsite>
202 <ftppath>/debian/doc/package-developer/policy.txt.gz</ftppath>
203 (also available from the same directory are several other
204 formats: <tt>policy.html.tar.gz</tt>, <tt>policy.pdf.gz</tt>
205 and <tt>policy.ps.gz</tt>) or from the <url
206 id="http://www.debian.org/doc/debian-policy/" name="Debian
207 Policy Manual"> webpage.</p>
210 In addition, this manual is distributed via the Debian package
211 <tt>debian-policy</tt>.
215 The <tt>debian-policy</tt> package also includes the file
216 <tt>upgrading-checklist.txt</tt> which indicates policy
217 changes between versions of this document.
221 <heading>Feedback</heading>
224 As the Debian GNU/Linux system is continuously evolving this
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.
240 <heading>The Debian Archive</heading>
242 The Debian GNU/Linux system is maintained and distributed as a
243 collection of <em>packages</em>. Since there are so many of
244 them (currently well over 6000), they are split into
245 <em>sections</em> and given <em>priorities</em> to simplify
246 the handling of them.
249 The effort of the Debian project is to build a free operating
250 system, but not every package we want to make accessible is
251 <em>free</em> in our sense (see the Debian Free Software
252 Guidelines, below), or may be imported/exported without
253 restrictions. Thus, the archive is split into the sections
254 <em>main</em>, <em>non-free</em>, <em>contrib</em>,
255 <em>non-US/main</em>, <em>non-US/non-free</em>, and
256 <em>non-US/contrib</em>. The sections are explained in detail
261 The <em>main</em> and the <em>non-US/main</em> sections
262 together form the <em>Debian GNU/Linux distribution</em>.
266 Packages in the other sections are not considered to be part
267 of the Debian distribution, although we support their use and
268 provide infrastructure for them (such as our bug-tracking
269 system and mailing lists). This Debian Policy Manual applies
270 to these packages as well.</p>
272 <sect id="pkgcopyright">
273 <heading>Package copyright and sections</heading>
275 The aims of this section are:
277 <list compact="compact">
279 <p>to allow us to make as much software available as we
283 <p>to allow us to encourage everyone to write free
287 <p>to allow us to make it easy for people to produce
288 CD-ROMs of our system without violating any licenses,
289 import/export restrictions, or any other laws.</p>
294 <heading>The Debian Free Software Guidelines</heading>
296 The Debian Free Software Guidelines (DFSG) form our
297 definition of `free software'. These are:
299 <tag>Free Redistribution
303 The license of a Debian component may not restrict any
304 party from selling or giving away the software as a
305 component of an aggregate software distribution
306 containing programs from several different
307 sources. The license may not require a royalty or
308 other fee for such sale.
315 The program must include source code, and must allow
316 distribution in source code as well as compiled form.
323 The license must allow modifications and derived
324 works, and must allow them to be distributed under the
325 same terms as the license of the original software.
328 <tag>Integrity of The Author's Source Code
332 The license may restrict source-code from being
333 distributed in modified form <em>only</em> if the
334 license allows the distribution of ``patch files''
335 with the source code for the purpose of modifying the
336 program at build time. The license must explicitly
337 permit distribution of software built from modified
338 source code. The license may require derived works to
339 carry a different name or version number from the
340 original software. (This is a compromise. The Debian
341 Project encourages all authors to not restrict any
342 files, source or binary, from being modified.)
345 <tag>No Discrimination Against Persons or Groups
349 The license must not discriminate against any person
353 <tag>No Discrimination Against Fields of Endeavor
357 The license must not restrict anyone from making use
358 of the program in a specific field of endeavor. For
359 example, it may not restrict the program from being
360 used in a business, or from being used for genetic
364 <tag>Distribution of License
368 The rights attached to the program must apply to all
369 to whom the program is redistributed without the need
370 for execution of an additional license by those
374 <tag>License Must Not Be Specific to Debian
378 The rights attached to the program must not depend on
379 the program's being part of a Debian system. If the
380 program is extracted from Debian and used or
381 distributed without Debian but otherwise within the
382 terms of the program's license, all parties to whom
383 the program is redistributed must have the same
384 rights as those that are granted in conjunction with
388 <tag>License Must Not Contaminate Other Software
392 The license must not place restrictions on other
393 software that is distributed along with the licensed
394 software. For example, the license must not insist
395 that all other programs distributed on the same medium
396 must be free software.
399 <tag>Example Licenses
403 The ``GPL,'' ``BSD,'' and ``Artistic'' licenses are
404 examples of licenses that we consider <em>free</em>.
411 <heading>The main section</heading>
413 Every package in <em>main</em> and <em>non-US/main</em>
414 must comply with the DFSG (Debian Free Software
418 In addition, the packages in <em>main</em>
419 <list compact="compact">
422 must not require a package outside of <em>main</em>
423 for compilation or execution (thus, the package must
424 not declare a "Depends", "Recommends", or
425 "Build-Depends" relationship on a non-<em>main</em>
431 must not be so buggy that we refuse to support them,
437 must meet all policy requirements presented in this
444 Similarly, the packages in <em>non-US/main</em>
445 <list compact="compact">
448 must not require a package outside of <em>main</em>
449 or <em>non-US/main</em> for compilation or
455 must not be so buggy that we refuse to support them,
460 must meet all policy requirements presented in this
468 <heading>The contrib section</heading>
470 Every package in <em>contrib</em> and
471 <em>non-US/contrib</em> must comply with the DFSG.
475 In addition, the packages in <em>contrib</em> and
476 <em>non-US/contrib</em>
477 <list compact="compact">
480 must not be so buggy that we refuse to support them,
486 must meet all policy requirements presented in this
494 Furthermore, packages in <em>contrib</em> must not require
495 a package in a <em>non-US</em> section for compilation or
500 Examples of packages which would be included in
501 <em>contrib</em> or <em>non-US/contrib</em> are:
502 <list compact="compact">
505 free packages which require <em>contrib</em>,
506 <em>non-free</em> packages or packages which are not
507 in our archive at all for compilation or execution,
513 wrapper packages or other sorts of free accessories for
521 <heading>The non-free section</heading>
523 Packages must be placed in <em>non-free</em> or
524 <em>non-US/non-free</em> if they are not compliant with
525 the DFSG or are encumbered by patents or other legal
526 issues that make their distribution problematic.
529 In addition, the packages in <em>non-free</em> and
530 <em>non-US/non-free</em>
531 <list compact="compact">
534 must not be so buggy that we refuse to support them,
540 must meet all policy requirements presented in this
541 manual that it is possible for them to meet.
544 It is possible that there are policy
545 requirements which the package is unable to
546 meet, for example, if the source is
547 unavailable. These situations will need to be
548 handled on a case-by-case basis.
558 <heading>The non-US sections</heading>
560 Some programs with cryptographic program code need to be
561 stored on the <em>non-US</em> server because of United
562 States export restrictions. Such programs must be
563 distributed in the appropriate <em>non-US</em> section,
564 either <em>non-US/main</em>, <em>non-US/contrib</em> or
565 <em>non-US/non-free</em>.
568 This applies only to packages which contain cryptographic
569 code. A package containing a program with an interface to
570 a cryptographic program or a program that's dynamically
571 linked against a cryptographic library should not be
572 distributed via the <em>non-US</em> server if it is
573 capable of running without the cryptographic library or
578 <heading>Further copyright considerations</heading>
580 Every package must be accompanied by a verbatim copy of
581 its copyright and distribution license in the file
582 <tt>/usr/share/doc/<em><package></em>/copyright</tt>
583 (see <ref id="copyrightfile"> for further details).
586 We reserve the right to restrict files from being included
587 anywhere in our archives if
588 <list compact="compact">
591 their use or distribution would break a law,
596 there is an ethical conflict in their distribution or
602 we would have to sign a license for them, or
607 their distribution would conflict with other project
615 Programs whose authors encourage the user to make
616 donations are fine for the main distribution, provided
617 that the authors do not claim that not donating is
618 immoral, unethical, illegal or something similar; in such
619 a case they must go in <em>non-free</em>.</p>
622 Packages whose copyright permission notices (or patent
623 problems) do not even allow redistribution of binaries
624 only, and where no special permission has been obtained,
625 must not be placed on the Debian FTP site and its mirrors
629 Note that under international copyright law (this applies
630 in the United States, too), <em>no</em> distribution or
631 modification of a work is allowed without an explicit
632 notice saying so. Therefore a program without a copyright
633 notice <em>is</em> copyrighted and you may not do anything
634 to it without risking being sued! Likewise if a program
635 has a copyright notice but no statement saying what is
636 permitted then nothing is permitted.</p>
639 Many authors are unaware of the problems that restrictive
640 copyrights (or lack of copyright notices) can cause for
641 the users of their supposedly-free software. It is often
642 worthwhile contacting such authors diplomatically to ask
643 them to modify their license terms. However, this can be a
644 politically difficult thing to do and you should ask for
645 advice on the <tt>debian-legal</tt> mailing list first, as
650 When in doubt about a copyright, send mail to
651 <email>debian-legal@lists.debian.org</email>. Be prepared
652 to provide us with the copyright statement. Software
653 covered by the GPL, public domain software and BSD-like
654 copyrights are safe; be wary of the phrases `commercial
655 use prohibited' and `distribution restricted'.
659 <heading>Subsections</heading>
662 The packages in the sections <em>main</em>,
663 <em>contrib</em> and <em>non-free</em> are grouped further
664 into <em>subsections</em> to simplify handling.
668 The section and subsection for each package should be
669 specified in the package's <tt>Section</tt> control
670 record. However, the maintainer of the Debian archive
671 may override this selection to ensure the consistency of
672 the Debian distribution. The <tt>Section</tt> field
673 should be of the form:
674 <list compact="compact">
677 <em>subsection</em> if the package is in the
678 <em>main</em> section,
683 <em>section/subsection</em> if the package is in
684 the <em>contrib</em> or <em>non-free</em> section,
690 <tt>non-US</tt>, <tt>non-US/contrib</tt> or
691 <tt>non-US/non-free</tt> if the package is in
692 <em>non-US/main</em>, <em>non-US/contrib</em> or
693 <em>non-US/non-free</em> respectively.
700 The Debian archive maintainers provide the authoritative
701 list of subsections. At present, they are:
702 <em>admin</em>, <em>base</em>, <em>comm</em>,
703 <em>contrib</em>, <em>devel</em>, <em>doc</em>,
704 <em>editors</em>, <em>electronics</em>, <em>games</em>,
705 <em>graphics</em>, <em>hamradio</em>,
706 <em>interpreters</em>, <em>libs</em>, <em>mail</em>,
707 <em>math</em>, <em>misc</em>, <em>net</em>, <em>news</em>,
708 <em>non-US</em>, <em>non-free</em>, <em>oldlibs</em>,
709 <em>otherosfs</em>, <em>science</em>, <em>shells</em>,
710 <em>sound</em>, <em>tex</em>, <em>text</em>,
711 <em>utils</em>, <em>web</em>, <em>x11</em>.
715 <heading>Priorities</heading>
718 Each package should have a <em>priority</em> value, which is
719 included in the package's <em>control record</em>. This
720 information is used by the Debian package management tools
721 to separate high-priority packages from less-important
725 The following <em>priority levels</em> are recognised by the
726 Debian package management tools.
728 <tag><tt>required</tt></tag>
731 Packages which are necessary for the proper
732 functioning of the system. You must not remove these
733 packages or your system may become totally broken and
734 you may not even be able to use <prgn>dpkg</prgn> to
735 put things back. Systems with only the
736 <tt>required</tt> packages are probably unusable, but
737 they do have enough functionality to allow the
738 sysadmin to boot and install more software.</p>
740 <tag><tt>important</tt></tag>
743 Important programs, including those which one would
744 expect to find on any Unix-like system. If the
745 expectation is that an experienced Unix person who
746 found it missing would say `What on earth is going on,
747 where is <prgn>foo</prgn>?', it must be an
748 <tt>important</tt> package.
751 This is an important criterion because we are
752 trying to produce, amongst other things, a free
756 Other packages without which the system will not run
757 well or be usable must also have priority
758 <tt>important</tt>. This does
759 <em>not</em> include Emacs, the X Window System, TeX
760 or any other large applications. The
761 <tt>important</tt> packages are just a bare minimum of
762 commonly-expected and necessary tools.</p>
764 <tag><tt>standard</tt></tag>
767 These packages provide a reasonably small but not too
768 limited character-mode system. This is what will be
769 installed by default if the user doesn't select anything
770 else. It doesn't include many large applications, but
771 it does include Emacs (this is more of a piece of
772 infrastructure than an application) and a reasonable
773 subset of TeX and LaTeX.</p>
775 <tag><tt>optional</tt></tag>
778 (In a sense everything that isn't required is
779 optional, but that's not what is meant here.) This is
780 all the software that you might reasonably want to
781 install if you didn't know what it was and don't have
782 specialized requirements. This is a much larger system
783 and includes the X Window System, a full TeX
784 distribution, and many applications. Note that
785 optional packages should not conflict with each other.
788 <tag><tt>extra</tt></tag>
791 This contains all packages that conflict with others
792 with required, important, standard or optional
793 priorities, or are only likely to be useful if you
794 already know what they are or have specialised
801 Packages must not depend on packages with lower priority
802 values (excluding build-time dependencies). In order to
803 ensure this, the priorities of one or more packages may need
809 <heading>Binary packages</heading>
812 The Debian GNU/Linux distribution is based on the Debian
813 package management system, called <prgn>dpkg</prgn>. Thus,
814 all packages in the Debian distribution must be provided
815 in the <tt>.deb</tt> file format.</p>
819 <heading>The package name</heading>
822 Every package must have a name that's unique within the Debian
826 Package names must consist of lower case letters (a-z),
827 digits (0-9), plus (+) and minus (-) signs, and periods
828 (.). They must be at least two characters long and must
829 contain at least one letter.
833 The package name is part of the file name of the
834 <tt>.deb</tt> file and is included in the control field
840 <heading>The maintainer of a package</heading>
842 Every package must have a Debian maintainer (the
843 maintainer may be one person or a group of people
844 reachable from a common email address, such as a mailing
845 list). The maintainer is responsible for ensuring that
846 the package is placed in the appropriate distributions.
850 The maintainer must be specified in the
851 <tt>Maintainer</tt> control field with their correct name
852 and a working email address. If one person maintains
853 several packages, he/she should try to avoid having
854 different forms of their name and email address in
855 the <tt>Maintainer</tt> fields of those packages.
859 If the maintainer of a package quits from the Debian
860 project, "Debian QA Group"
861 <email>packages@qa.debian.org</email> takes over the
862 maintainership of the package until someone else
863 volunteers for that task. These packages are called
864 <em>orphaned packages</em>.
867 The detailed procedure for doing this gracefully can
868 be found in the Debian Developer's Reference, either
869 in the <tt>developers-reference</tt> package, or on
870 the Debian FTP server
871 <ftpsite>ftp.debian.org</ftpsite> as
872 <ftppath>/debian/doc/package-developer/developers-reference.txt.gz</ftppath>
874 id="http://www.debian.org/doc/packaging-manuals/developers-reference/"
875 name="Debian Developer's Reference"> webpage.
883 <heading>The description of a package</heading>
886 Every Debian package must have an extended description
887 stored in the appropriate field of the control record.</p>
890 The description should be written so that it gives the
891 system administrator enough information to decide whether
892 to install the package. This description should not just
893 be copied verbatim from the program's documentation.
894 Instructions for configuring or using the package should
895 not be included -- that is what installation scripts,
896 manual pages, info files, etc., are for. Copyright
897 statements and other administrivia should not be included
898 either -- that is what the copyright file is for.</p>
903 <heading>Dependencies</heading>
906 Every package must specify the dependency information
907 about other packages that are required for the first to
911 For example, a dependency entry must be provided for any
912 shared libraries required by a dynamically-linked executable
913 binary in a package.</p>
916 Packages are not required to declare any dependencies they
917 have on other packages which are marked <tt>Essential</tt>
918 (see below), and should not do so unless they depend on a
919 particular version of that package.</p>
922 Sometimes, a package requires another package to be installed
923 <em>and</em> configured before it can be installed. In this
924 case, you must specify a <tt>Pre-Depends</tt> entry for
928 You should not specify a <tt>Pre-Depends</tt> entry for a
929 package before this has been discussed on the
930 <tt>debian-devel</tt> mailing list and a consensus about
931 doing that has been reached.</p></sect1>
935 <heading>Virtual packages</heading>
938 Sometimes, there are several packages which offer
939 more-or-less the same functionality. In this case, it's
940 useful to define a <em>virtual package</em> whose name
941 describes that common functionality. (The virtual
942 packages only exist logically, not physically--that's why
943 they are called <em>virtual</em>.) The packages with this
944 particular function will then <em>provide</em> the virtual
945 package. Thus, any other package requiring that function
946 can simply depend on the virtual package without having to
947 specify all possible packages individually.</p>
950 All packages should use virtual package names where
951 appropriate, and arrange to create new ones if necessary.
952 They should not use virtual package names (except privately,
953 amongst a cooperating group of packages) unless they have
954 been agreed upon and appear in the list of virtual package
958 The latest version of the authoritative list of virtual
959 package names can be found on
960 <ftpsite>ftp.debian.org</ftpsite> in
961 <ftppath>/debian/doc/package-developer/virtual-package-names-list.txt</ftppath>
962 or your local mirror. In addition, it is included in the
963 <tt>debian-policy</tt> package. The procedure for updating
964 the list is described at the top of the file.</p></sect1>
968 <heading>Base packages</heading>
971 The packages included in the <tt>base</tt> section have a
972 special function. They form a minimum subset of the Debian
973 GNU/Linux system that is installed before everything else
974 on a new system. Thus, only very few packages are allowed
975 to go into the <tt>base</tt> section to keep the required
976 disk usage very small.</p>
979 Most of these packages will have the priority value
980 <tt>required</tt> or at least <tt>important</tt>, and many
981 of them will be tagged <tt>essential</tt> (see below).</p>
984 You must not place any packages into the <tt>base</tt>
985 section before this has been discussed on the
986 <tt>debian-devel</tt> mailing list and a consensus about
987 doing that has been reached.</p></sect1>
991 <heading>Essential packages</heading>
994 Some packages are tagged <tt>essential</tt>. (They have
995 <tt>Essential: yes</tt> in their package control record.)
996 This flag is used for packages that are <em>essential</em>
1000 Since these packages cannot be easily removed (one has to
1001 specify an extra <em>force option</em> to
1002 <prgn>dpkg</prgn> to do so), this flag must not be used
1003 unless absolutely necessary. A shared library package
1004 must not be tagged <tt>essential</tt>--dependencies will
1005 prevent its premature removal, and we need to be able to
1006 remove it when it has been superseded.
1010 Since dpkg will not prevent upgrading of other packages
1011 while an <tt>essential</tt> package is in an unconfigured
1012 state, all <tt>essential</tt> packages must supply all of
1013 their core functionality even when unconfigured. If the
1014 package cannot satisfy this requirement it must not be
1015 tagged as essential, and any packages depending on this
1016 package must instead have explicit dependency fields as
1021 You must not tag any packages <tt>essential</tt> before
1022 this has been discussed on the <tt>debian-devel</tt>
1023 mailing list and a consensus about doing that has been
1029 <heading>Maintainer scripts</heading>
1032 The package installation scripts should avoid producing
1033 output which it is unnecessary for the user to see and
1034 should rely on <prgn>dpkg</prgn> to stave off boredom on
1035 the part of a user installing many packages. This means,
1036 amongst other things, using the <tt>--quiet</tt> option on
1037 <prgn>install-info</prgn>.</p>
1040 Errors which occur during the execution of an installation
1041 script must be checked and the installation must not
1042 continue after an error.
1046 Note that in general <ref id="scripts"> applies to package
1047 maintainer scripts, too.
1051 You should not use <tt>dpkg-divert</tt> on a file
1052 belonging to another package without consulting the
1053 maintainer of that package first.
1056 All packages which supply an instance of a common command
1057 name (or, in general, filename) should generally use
1058 <prgn>update-alternatives</prgn>, so that they may be
1059 installed together. If <prgn>update-alternatives</prgn>
1060 is not used, then each package must use
1061 <var>Conflicts</var> to ensure that other packages are
1062 de-installed. (In this case, it may be appropriate to
1063 specify a conflict against earlier versions of something
1064 that previously did not use
1065 <prgn>update-alternatives</prgn> - this is an exception to
1066 the usual rule that versioned conflicts should be
1072 <heading>Prompting in maintainer scripts</heading>
1074 Package maintainer scripts may prompt the user if
1075 necessary. Prompting may be accomplished by hand, or by
1076 communicating with a program, such as
1077 <prgn>debconf</prgn>, which conforms to the Debian
1078 Configuration management specification, version 2 or
1079 higher. These are included in the
1080 <file>debconf_specification</file> files in the
1081 <package>debian-policy</package> package.
1082 You may also find this file on the FTP site
1083 <ftpsite>ftp.debian.org</ftpsite> in
1084 <ftppath>/debian/doc/package-developer/debconf_specification.txt.gz</ftppath>
1085 or on your local mirror.
1088 2.5% of Debian packages [see <url
1089 id="http://kitenet.net/programs/debconf/stats/">]
1090 currently use <package>debconf</package> to prompt
1091 the user at install time, and this number is growing
1092 daily. The benefits of using debconf are briefly
1094 id="http://kitenet.net/doc/debconf-doc/introduction.html">;
1095 they include preconfiguration, (mostly)
1096 noninteractive installation, elimination of
1097 redundant prompting, consistency of user interface,
1101 With this increasing number of packages using
1102 <package>debconf</package>, plus the existance of a
1103 nascent second implementation of the Debian
1104 configuration management system
1105 (<package>cdebconf</package>), and the stabalization
1106 of the protocol these things use, the time has
1107 finally come to reflect the use of these things in
1114 Packages which use the Debian Configuration management
1115 specification may contain an additional
1116 <file>config</file> script and a <file>templates</file>
1117 file in their control archive. The <prgn>config</prgn>
1118 script might be run before the <prgn>preinst</prgn>
1119 script, and before the package is unpacked or any of its
1120 dependancies or pre-dependancies are satisfied.
1121 Therefore it must work using only the tools present in
1122 <em>essential</em> packages.
1125 <package>Debconf</package> or another tool that
1126 implements the Debian Configuration management
1127 specification will also be installed, and any
1128 versioned dependencies on it will be satisfied
1129 before preconfiguration begins.
1135 Packages should try to minimize the amount of prompting
1136 they need to do, and they should ensure that the user
1137 will only ever be asked each question once. This means
1138 that packages should try to use appropriate shared
1139 configuration files (such as <tt>/etc/papersize</tt> and
1140 <tt>/etc/news/server</tt>), and shared
1141 <package>debconf</package> variables rather than each
1142 prompting for their own list of required pieces of
1147 It also means that an upgrade should not ask the same
1148 questions again, unless the user has used <tt>dpkg
1149 --purge</tt> to remove the package's configuration. The
1150 answers to configuration questions should be stored in an
1151 appropriate place in <tt>/etc</tt> so that the user can
1152 modify them, and how this has been done should be
1156 If a package has a vitally important piece of
1157 information to pass to the user (such as "don't run me
1158 as I am, you must edit the following configuration files
1159 first or you risk your system emitting badly-formatted
1160 messages"), it should display this in the
1161 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1162 prompt the user to hit return to acknowledge the
1163 message. Copyright messages do not count as vitally
1164 important (they belong in
1165 <tt>/usr/share/doc/<var>package</var>/copyright</tt>);
1166 neither do instructions on how to use a program (these
1167 should be in on-line documentation, where all the users
1171 Any necessary prompting should almost always be confined
1172 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1173 script. If it is done in the <prgn>postinst</prgn>, it
1174 should be protected with a conditional so that unnecessary
1175 prompting doesn't happen if a package's installation fails
1176 and the <prgn>postinst</prgn> is called with
1177 <tt>abort-upgrade</tt>, <tt>abort-remove</tt> or
1178 <tt>abort-deconfigure</tt>.</p>
1183 <heading>Source packages</heading>
1185 <sect1 id="standardsversion">
1186 <heading>Standards conformance</heading>
1189 In the source package's <tt>Standards-Version</tt> control
1190 field, you must specify the most recent version number of
1191 this policy document with which your package complies.
1192 The current version number is &version;.
1196 This information may be used to file bug reports
1197 automatically if your package becomes too much out of
1202 The version number has four components--major and minor
1203 version number and major and minor patch level. When the
1204 standards change in a way that requires every package to
1205 change the major number will be changed. Significant
1206 changes that will require work in many packages will be
1207 signaled by a change to the minor number. The major patch
1208 level will be changed for any change to the meaning of the
1209 standards, however small; the minor patch level will be
1210 changed when only cosmetic, typographical or other edits
1211 are made which neither change the meaning of the document
1212 nor affect the contents of packages.</p>
1215 Thus only the first three components of the policy version
1216 are significant in the <em>Standards-Version</em> control
1217 field, and so either these three components or the all
1218 four components may be specified.
1221 In the past, people specified the full version number
1222 in the Standards-Version field, for example `2.3.0.0'.
1223 Since minor patch-level changes don't introduce new
1224 policy, it was thought it would be better to relax
1225 policy and only require the first 3 components to be
1226 specified, in this example `2.3.0'. All four
1227 components may still be used if someone wishes to do
1234 You should regularly, and especially if your package has
1235 become out of date, check for the newest Policy Manual
1236 available and update your package, if necessary. When your
1237 package complies with the new standards you should update the
1238 <tt>Standards-Version</tt> source package field and
1242 See the file <tt>upgrading-checklist</tt> for
1243 information about policy which has changed between
1244 different versions of this document.
1252 <heading>Package relationships</heading>
1255 Source packages should specify which binary packages they
1256 require to be installed or not to be installed in order to
1257 build correctly. For example, if building a package
1258 requires a certain compiler, then the compiler should be
1259 specified as a build-time dependency.
1263 It is not necessary to explicitly specify build-time
1264 relationships on a minimal set of packages that are always
1265 needed to compile, link and put in a Debian package a
1266 standard "Hello World!" program written in C or C++. The
1267 required packages are called <em>build-essential</em>, and
1268 an informational list can be found in
1269 <tt>/usr/share/doc/build-essential/list</tt> (which is
1270 contained in the <tt>build-essential</tt>
1276 <p>This allows maintaining the list separately
1277 from the policy documents (the list does not
1278 need the kind of control that the policy
1284 Having a separate package allows one to install
1285 the build-essential packages on a machine, as
1286 well as allowing other packages such as task
1287 packages to require installation of the
1288 build-essential packages using the depends
1294 The separate package allows bug reports against
1295 the list to be categorized separately from
1296 the policy management process in the BTS.
1306 When specifying the set of build-time dependencies, one
1307 should list only those packages explicitly required by the
1308 build. It is not necessary to list packages which are
1309 required merely because some other package in the list of
1310 build-time dependencies depends on them.
1313 The reason for this is that dependencies change, and
1314 you should list all those packages, and <em>only</em>
1315 those packages that <em>you</em> need directly. What
1316 others need is their business. For example, if you
1317 only link against <tt>libimlib</tt>, you will need to
1318 build-depend on <package>libimlib2-dev</package> but
1319 not against any <tt>libjpeg*</tt> packages, even
1320 though <tt>libimlib2-dev</tt> currently depends on
1321 them: installation of <package>libimlib2-dev</package>
1322 will automatically ensure that all of its run-time
1323 dependencies are satisfied.
1329 If build-time dependencies are specified, it must be
1330 possible to build the package and produce working binaries
1331 on a system with only essential and build-essential
1332 packages installed and also those required to satisfy the
1333 build-time relationships (including any implied
1334 relationships). In particular, this means that version
1335 clauses should be used rigorously in build-time
1336 relationships so that one cannot produce bad or
1337 inconsistently configured packages when the relationships
1338 are properly satisfied.
1342 <heading>Changes to the upstream sources</heading>
1345 If changes to the source code are made that are not
1346 specific to the needs of the Debian system, they should be
1347 sent to the upstream authors in whatever form they prefer
1348 so as to be included in the upstream version of the
1352 If you need to configure the package differently for
1353 Debian or for Linux, and the upstream source doesn't
1354 provide a way to do so, you should add such configuration
1355 facilities (for example, a new <prgn>autoconf</prgn> test
1356 or <tt>#define</tt>) and send the patch to the upstream
1357 authors, with the default set to the way they originally
1358 had it. You can then easily override the default in your
1359 <tt>debian/rules</tt> or wherever is appropriate.</p>
1362 You should make sure that the <prgn>configure</prgn> utility
1363 detects the correct architecture specification string
1364 (refer to <ref id="arch-spec"> for details).</p>
1367 If you need to edit a <prgn>Makefile</prgn> where
1368 GNU-style <prgn>configure</prgn> scripts are used, you
1369 should edit the <tt>.in</tt> files rather than editing the
1370 <prgn>Makefile</prgn> directly. This allows the user to
1371 reconfigure the package if necessary. You should
1372 <em>not</em> configure the package and edit the generated
1373 <prgn>Makefile</prgn>! This makes it impossible for
1374 someone else to later reconfigure the package.</p></sect1>
1378 <heading>Documenting your changes</heading>
1381 You should document your changes and updates to the source
1382 package properly in the <tt>debian/changelog</tt> file. (Note
1383 that mistakes in changelogs are usually best rectified by
1384 making a new changelog entry rather than "rewriting history"
1385 by editing old changelog entries.)</p>
1388 In non-experimental packages you must use a format for
1389 <tt>debian/changelog</tt> which is supported by the most
1390 recent released version of <prgn>dpkg</prgn>.
1393 If you wish to use an alternative format, you may do
1394 so as long as you include a parser for it in your
1395 source package. The parser must have an API
1396 compatible with that expected by
1397 <prgn>dpkg-genchanges</prgn> and
1398 <prgn>dpkg-gencontrol</prgn>. If there is general
1399 interest in the new format, you should contact the
1400 <package>dpkg</package> maintainer to have the parser
1401 script for it included in the <prgn>dpkg</prgn>
1402 package. (You will need to agree that the parser and
1403 its manpage may be distributed under the GNU GPL, just
1404 as the rest of `dpkg' is.)
1412 <heading>Error trapping in makefiles</heading>
1415 When <prgn>make</prgn> invokes a command in a makefile
1416 (including your package's upstream makefiles and
1417 <tt>debian/rules</tt>), it does so using <tt>sh</tt>. This
1418 means that <tt>sh</tt>'s usual bad error handling
1419 properties apply: if you include a miniature script as one
1420 of the commands in your makefile you'll find that if you
1421 don't do anything about it then errors are not detected
1422 and <prgn>make</prgn> will blithely continue after
1426 Every time you put more than one shell command (this
1427 includes using a loop) in a makefile command you
1428 must make sure that errors are trapped. For
1429 simple compound commands, such as changing directory and
1430 then running a program, using <tt>&&</tt> rather
1431 than semicolon as a command separator is sufficient. For
1432 more complex commands including most loops and
1433 conditionals you should include a separate <tt>set -e</tt>
1434 command at the start of every makefile command that's
1435 actually one of these miniature shell scripts.</p></sect1>
1439 <heading>Obsolete constructs and libraries</heading>
1442 The include file <prgn><varargs.h></prgn> is
1443 provided to support end-users compiling very old software;
1444 the library <tt>libtermcap</tt> is provided to support the
1445 execution of software which has been linked against it
1446 (either old programs or those such as Netscape which are
1447 only available in binary form).</p>
1450 Debian packages should be patched to use
1451 <prgn><stdarg.h></prgn> and <tt>ncurses</tt>
1458 <chapt id="controlfields"><heading>Control files and their fields</heading>
1461 Many of the tools in the package management suite manipulate
1462 data represented in a common format, known as <em>control
1463 data</em>. The data is often stored in <em>control
1464 files</em>. Binary and source packages have control files,
1465 and the <tt>.changes</tt> files which control the installation
1466 of uploaded files are also in control file format.
1467 <prgn>Dpkg</prgn>'s internal databases are in a similar
1471 <sect id="controlsyntax"><heading>Syntax of control files</heading>
1474 A control file consists of one or more paragraphs of fields.
1475 The paragraphs are separated by blank lines. Some control
1476 files allow only one paragraph; others allow several, in
1477 which case each paragraph usually refers to a different
1478 package. (For example, in source packages, the first
1479 paragraph refers to the source package, and later paragraphs
1480 refer to binary packages generated from the source.)
1484 Each paragraph consists of a series of data fields; each
1485 field consists of the field name, followed by a colon and
1486 then the data/value associated with that field. It ends at
1487 the end of the line. Horizontal whitespace (spaces and
1488 tabs) may occur immediately before or after the value and is
1489 ignored there; it is conventional to put a single space
1490 after the colon. For example, a field might be:
1494 the field name is <tt>Package</tt> and the field value
1499 Some fields' values may span several lines; in this case
1500 each continuation line <em>must</em> start with a space or
1501 tab. Any trailing spaces or tabs at the end of individual
1502 lines of a field value are ignored.
1506 Except where otherwise stated only a single line of data is
1507 allowed and whitespace is not significant in a field body.
1508 Whitespace must not appear inside names (of packages,
1509 architectures, files or anything else) or version numbers,
1510 or between the characters of multi-character version
1515 Field names are not case-sensitive, but it is usual to
1516 capitalize the field names using mixed case as shown below.
1520 Blank lines, or lines consisting only of spaces and tabs,
1521 are not allowed within field values or between fields - that
1522 would mean a new paragraph.
1527 <sect><heading>List of fields</heading>
1529 This list here is not supposed to be exhaustive. Most fields
1530 are dealt with elsewhere in this document.
1532 <sect1 id="f-Package"><heading><tt>Package</tt>
1536 The name of the binary package. Package names consist of
1537 the alphanumerics and <tt>+</tt> <tt>-</tt> <tt>.</tt>
1538 (plus, minus and full stop).
1542 They must be at least two characters long and must start
1543 with an alphanumeric character and not be all digits. The
1544 use of lowercase package names is strongly recommended
1545 unless the package you're building (or referring to, in
1546 other fields) is already using uppercase.</p>
1549 <sect1 id="f-Version"><heading><tt>Version</tt>
1553 This lists the source or binary package's version number -
1554 see <ref id="versions">.
1560 id="f-Standards-Version"><heading><tt>Standards-Version</tt>
1564 The most recent version of the standards (the policy
1565 manual and associated texts) with which the package
1566 complies. This is updated manually when editing the
1567 source package to conform to newer standards; it can
1568 sometimes be used to tell when a package needs attention.
1569 Its format is described above; see
1570 <ref id="standardsversion">.
1575 <sect1 id="f-Distribution"><heading><tt>Distribution</tt>
1579 In a <tt>.changes</tt> file or parsed changelog output
1580 this contains the (space-separated) name(s) of the
1581 distribution(s) where this version of the package should
1582 be installed. Valid distributions are determined by the
1583 archive maintainers.
1585 Current distribution names are:
1587 <tag><em>stable</em></tag>
1590 This is the current `released' version of Debian
1591 GNU/Linux. Once the distribution is
1592 <em>stable</em> only security fixes and other
1593 major bug fixes are allowed. When changes are
1594 made to this distribution, the release number is
1595 increased (for example: 2.2r1 becomes 2.2r2 then
1600 <tag><em>unstable</em></tag>
1603 This distribution value refers to the
1604 <em>developmental</em> part of the Debian
1605 distribution tree. New packages, new upstream
1606 versions of packages and bug fixes go into the
1607 <em>unstable</em> directory tree. Download from
1608 this distribution at your own risk.
1612 <tag><em>testing</em></tag>
1615 This distribution value refers to the
1616 <em>testing</em> part of the Debian distribution
1617 tree. It receives its packages from the
1618 unstable distribution after a short time lag to
1619 ensure that there are no major issues with the
1620 unstable packages. It is less prone to breakage
1621 than unstable, but still risky. It is not
1622 possible to upload packages directly to
1627 <tag><em>frozen</em></tag>
1630 From time to time, the <em>frozen</em>
1631 distribution enters a state of `code-freeze' in
1632 anticipation of release as a <em>stable</em>
1633 version. During this period of testing only
1634 fixes for existing or newly-discovered bugs will
1635 be allowed. The exact details of this stage are
1636 determined by the Release Manager.
1640 <tag><em>experimental</em></tag>
1643 The packages with this distribution value are
1644 deemed by their maintainers to be high
1645 risk. Oftentimes they represent early beta or
1646 developmental packages from various sources that
1647 the maintainers want people to try, but are not
1648 ready to be a part of the other parts of the
1649 Debian distribution tree. Download at your own
1655 You should list <em>all</em> distributions that the
1656 package should be installed into.
1665 <chapt id="versions"><heading>Version numbering</heading>
1668 Every package has a version number recorded in its
1669 <tt>Version</tt> control file field.
1673 The package management system imposes an ordering on version
1674 numbers, so that it can tell whether packages are being up- or
1675 downgraded and so that package system front end applications
1676 can tell whether a package it finds available is newer than
1677 the one installed on the system. The version number format
1678 has the most significant parts (as far as comparison is
1679 concerned) at the beginning.
1683 The version number format is:
1684 &lsqb<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
1688 The three components here are:
1690 <tag><var>epoch</var></tag>
1694 This is a single (generally small) unsigned integer. It
1695 may be omitted, in which case zero is assumed. If it is
1696 omitted then the <var>upstream_version</var> may not
1701 It is provided to allow mistakes in the version numbers
1702 of older versions of a package, and also a package's
1703 previous version numbering schemes, to be left behind.
1708 <tag><var>upstream_version</var></tag>
1712 This is the main part of the version number. It is
1713 usually the version number of the original (`upstream')
1714 package from which the <tt>.deb</tt> file has been made,
1715 if this is applicable. Usually this will be in the same
1716 format as that specified by the upstream author(s);
1717 however, it may need to be reformatted to fit into the
1718 package management system's format and comparison
1723 The comparison behavior of the package management system
1724 with respect to the <var>upstream_version</var> is
1725 described below. The <var>upstream_version</var>
1726 portion of the version number is mandatory.
1730 The <var>upstream_version</var> may contain only
1733 <p>Alphanumerics are <tt>A-Za-z0-9</tt> only.</p>
1735 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
1736 <tt>:</tt> (full stop, plus, hyphen, colon) and should
1737 start with a digit. If there is no
1738 <var>debian_revision</var> then hyphens are not allowed;
1739 if there is no <var>epoch</var> then colons are not
1743 <tag><var>debian_revision</var></tag>
1747 This part of the version number specifies the version of
1748 the Debian package based on the upstream version. It
1749 may contain only alphanumerics and the characters
1750 <tt>+</tt> and <tt>.</tt> (plus and full stop) and is
1751 compared in the same way as the
1752 <var>upstream_version</var> is.
1756 It is optional; if it isn't present then the
1757 <var>upstream_version</var> may not contain a hyphen.
1758 This format represents the case where a piece of
1759 software was written specifically to be turned into a
1760 Debian package, and so there is only one `debianization'
1761 of it and therefore no revision indication is required.
1765 It is conventional to restart the
1766 <var>debian_revision</var> at <tt>1</tt> each time the
1767 <var>upstream_version</var> is increased.
1771 The package management system will break the version
1772 number apart at the last hyphen in the string (if there
1773 is one) to determine the <var>upstream_version</var> and
1774 <var>debian_revision</var>. The absence of a
1775 <var>debian_revision</var> compares earlier than the
1776 presence of one (but note that the
1777 <var>debian_revision</var> is the least significant part
1778 of the version number).
1782 The <var>upstream_version</var> and <var>debian_revision</var>
1783 parts are compared by the package management system using the
1788 The strings are compared from left to right.
1792 First the initial part of each string consisting entirely of
1793 non-digit characters is determined. These two parts (one of
1794 which may be empty) are compared lexically. If a difference
1795 is found it is returned. The lexical comparison is a
1796 comparison of ASCII values modified so that all the letters
1797 sort earlier than all the non-letters.
1801 Then the initial part of the remainder of each string which
1802 consists entirely of digit characters is determined. The
1803 numerical values of these two parts are compared, and any
1804 difference found is returned as the result of the comparison.
1805 For these purposes an empty string (which can only occur at
1806 the end of one or both version strings being compared) counts
1811 These two steps (comparing and removing initial non-digit
1812 strings and initial digit strings) are repeated until a
1813 difference is found or both strings are exhausted.
1817 Note that the purpose of epochs is to allow us to leave behind
1818 mistakes in version numbering, and to cope with situations
1819 where the version numbering scheme changes. It is
1820 <em>not</em> intended to cope with version numbers containing
1821 strings of letters which the package management system cannot
1822 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
1823 silly orderings (the author of this manual has heard of a
1824 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
1825 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
1826 <tt>2</tt> and so forth).
1830 If an upstream package has problematic version numbers they
1831 should be converted to a sane form for use in the
1832 <tt>Version</tt> field.
1836 <heading>Version numbers based on dates</heading>
1838 In general, Debian packages should use the same version
1839 numbers as the upstream sources.</p>
1842 However, in some cases where the upstream version number is
1843 based on a date (e.g., a development `snapshot' release) the
1844 package management system cannot handle these version
1845 numbers without epochs. For example, dpkg will consider
1846 `96May01' to be greater than `96Dec24'.</p>
1849 To prevent having to use epochs for every new upstream
1850 version, the version number should be changed to the
1851 following format in such cases: `19960501', `19961224'. It
1852 is up to the maintainer whether he/she wants to bother the
1853 upstream maintainer to change the version numbers upstream,
1857 Note that other version formats based on dates which are
1858 parsed correctly by the package management system should
1859 <em>not</em> be changed.</p>
1862 Native Debian packages (i.e., packages which have been
1863 written especially for Debian) whose version numbers include
1864 dates should always use the `YYYYMMDD' format.</p>
1868 <chapt id="miscellaneous"><heading>Packaging Considerations</heading>
1870 <sect id="timestamps"><heading>Time Stamps</heading>
1872 Maintainers should preserve the modification times of the
1873 upstream source files in a package, as far as is reasonably
1877 The rationale is that there is some information conveyed
1878 by knowing the age of the file, for example, you could
1879 recognize that some documentation is very old by looking
1880 at the modification time, so it would be nice if the
1881 modification time of the upstream source would be
1888 <sect id="debianrules"><heading><tt>debian/rules</tt> - the
1889 main building script</heading>
1892 This file must be an executable makefile, and contains the
1893 package-specific recipes for compiling the package and
1894 building binary package(s) from the source.
1898 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1899 so that it can be invoked by saying its name rather than
1900 invoking <prgn>make</prgn> explicitly.
1904 Since an interactive <tt>debian/rules</tt> script makes it
1905 impossible to auto-compile that package and also makes it
1906 hard for other people to reproduce the same binary
1907 package, all <em>required targets</em> MUST be
1908 non-interactive. At a minimum, required targets are the
1909 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1910 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1911 <em>binary-indep</em>, and <em>build</em>. It also follows
1912 that any target that these targets depend on must also be
1917 The required and optional targets are as follows:
1919 <tag><tt>build</tt></tag>
1922 This should perform all non-interactive configuration
1923 and compilation of the package. If a package has an
1924 interactive pre-build configuration routine, the
1925 Debianized source package must either be built after
1926 this has taken place (so that the binary package can
1927 be built without rerunning the configuration) or the
1928 configuration routine modified to become
1929 non-interactive. (The latter is preferable if there
1930 are architecture-specific features detected by the
1931 configuration routine.)
1935 For some packages, notably ones where the same
1936 source tree is compiled in different ways to produce
1937 two binary packages, the <prgn>build</prgn> target
1938 does not make much sense. For these packages it is
1939 good enough to provide two (or more) targets
1940 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1941 for each of the ways of building the package, and a
1942 <prgn>build</prgn> target that does nothing. The
1943 <prgn>binary</prgn> target will have to build the
1944 package in each of the possible ways and make the
1945 binary package out of each.
1949 The <prgn>build</prgn> target must not do anything
1950 that might require root privilege.
1954 The <prgn>build</prgn> target may need to run the
1955 <prgn>clean</prgn> target first - see below.
1959 When a package has a configuration and build routine
1960 which takes a long time, or when the makefiles are
1961 poorly designed, or when <prgn>build</prgn> needs to
1962 run <prgn>clean</prgn> first, it is a good idea to
1963 <tt>touch build</tt> when the build process is
1964 complete. This will ensure that if <tt>debian/rules
1965 build</tt> is run again it will not rebuild the whole
1969 Another common way to do this is for <prgn>build</prgn>
1970 to depend on <prgn>build-stamp</prgn> and to do
1971 nothing else, and for the <prgn>build-stamp</prgn>
1972 target to do the building and to <tt>touch
1973 build-stamp</tt> on completion. This is
1974 especially useful if the build routine creates a
1975 file or directory called <tt>build</tt>; in such a
1976 case, <prgn>build</prgn> will need to be listed as
1977 a phony target (i.e., as a dependency of the
1978 <tt>.PHONY</tt> target). See the documentation of
1979 <prgn>make</prgn> for more information on phony
1986 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1987 <tt>binary-indep</tt>
1991 The <prgn>binary</prgn> target must be all that is
1992 necessary for the user to build the binary package(s)
1993 produced from this source package. All of these
1994 targets are required to be non-interactive. It is
1995 split into two parts: <prgn>binary-arch</prgn> builds
1996 the binary packages which are specific to a particular
1997 architecture, and <prgn>binary-indep</prgn> builds
1998 those which are not.
2002 <prgn>binary</prgn> may be (and commonly is) a target
2003 with no commands which simply depends on
2004 <prgn>binary-arch</prgn> and
2005 <prgn>binary-indep</prgn>.
2009 Each <prgn>binary-*</prgn> target should depend on
2010 the <prgn>build</prgn> target, above, so that the
2011 package is built if it has not been already. It
2012 should then create the relevant binary package(s),
2013 using <prgn>dpkg-gencontrol</prgn> to make their
2014 control files and <prgn>dpkg-deb</prgn> to build
2015 them and place them in the parent of the top level
2020 Both the <prgn>binary-arch</prgn> and
2021 <prgn>binary-indep</prgn> targets <em>must</em> exist.
2022 If one of them has nothing to do (which will always be
2023 the case if the source generates only a single binary
2024 package, whether architecture-dependent or not), it
2025 must still exist and must always succeed.
2029 The <prgn>binary</prgn> targets must be invoked as
2033 The <prgn>fakeroot</prgn> package often allows one
2034 to build a package correctly even without being
2041 <tag><tt>clean</tt></tag>
2045 This must undo any effects that the <prgn>build</prgn>
2046 and <prgn>binary</prgn> targets may have had, except
2047 that it should leave alone any output files created in
2048 the parent directory by a run of a <prgn>binary</prgn>
2049 target. This target must be non-interactive.
2053 If a <prgn>build</prgn> file is touched at the end of
2054 the <prgn>build</prgn> target, as suggested above, it
2055 should be removed as the first action that
2056 <prgn>clean</prgn> performs, so that running
2057 <prgn>build</prgn> again after an interrupted
2058 <prgn>clean</prgn> doesn't think that everything is
2063 The <prgn>clean</prgn> target may need to be
2064 invoked as root if <prgn>binary</prgn> has been
2065 invoked since the last <prgn>clean</prgn>, or if
2066 <prgn>build</prgn> has been invoked as root (since
2067 <prgn>build</prgn> may create directories, for
2072 <tag><tt>get-orig-source</tt> (optional)</tag>
2076 This target fetches the most recent version of the
2077 original source package from a canonical archive site
2078 (via FTP or WWW, for example), does any necessary
2079 rearrangement to turn it into the original source
2080 tar file format described below, and leaves it in the
2085 This target may be invoked in any directory, and
2086 should take care to clean up any temporary files it
2091 This target is optional, but providing it if
2092 possible is a good idea.
2098 The <prgn>build</prgn>, <prgn>binary</prgn> and
2099 <prgn>clean</prgn> targets must be invoked with the current
2100 directory being the package's top-level directory.
2105 Additional targets may exist in <tt>debian/rules</tt>,
2106 either as published or undocumented interfaces or for the
2107 package's internal use.
2111 The architectures we build on and build for are determined
2112 by <prgn>make</prgn> variables using the utility
2113 <prgn>dpkg-architecture</prgn>. You can determine the
2114 Debian architecture and the GNU style architecture
2115 specification string for the build machine (the machine type
2116 we are building on) as well as for the host machine (the
2117 machine type we are building for). Here is a list of
2118 supported <prgn>make</prgn> variables:
2119 <list compact="compact">
2121 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
2124 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2125 specification string)</p>
2128 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of
2129 <tt>DEB_*_GNU_TYPE</tt>)</p>
2132 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2133 <tt>DEB_*_GNU_TYPE</tt>)</p>
2135 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2136 the build machine or <tt>HOST</tt> for specification of the
2141 Backward compatibility can be provided in the rules file
2142 by setting the needed variables to suitable default
2143 values; please refer to the documentation of
2144 <prgn>dpkg-architecture</prgn> for details.
2148 It is important to understand that the <tt>DEB_*_ARCH</tt>
2149 string only determines which Debian architecture we are
2150 building on or for. It should not be used to get the CPU
2151 or system information; the GNU style variables should be
2156 <sect id="dpkgchangelog"><heading><tt>debian/changelog</tt>
2160 This file records the changes to the Debian-specific parts of the
2164 Though there is nothing stopping an author who is also
2165 the Debian maintainer from using it for all their
2166 changes, it will have to be renamed if the Debian and
2167 upstream maintainers become different people. In such a
2168 case, however, it might be better to maintain the
2169 package as a non-native package.
2175 It has a special format which allows the package building
2176 tools to discover which version of the package is being
2177 built and find out other release-specific information.
2181 That format is a series of entries like this:
2183 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
2185 * <var>change details</var>
2186 <var>more change details</var>
2187 * <var>even more change details</var>
2189 -- <var>maintainer name and email address</var> <var>date</var>
2194 <var>package</var> and <var>version</var> are the source
2195 package name and version number.
2199 <var>distribution(s)</var> lists the distributions where
2200 this version should be installed when it is uploaded - it
2201 is copied to the <tt>Distribution</tt> field in the
2202 <tt>.changes</tt> file. See <ref id="f-Distribution">.
2206 <var>urgency</var> is the value for the <tt>Urgency</tt>
2207 field in the <tt>.changes</tt> file for the upload. It is
2208 not possible to specify an urgency containing commas; commas
2209 are used to separate
2210 <tt><var>keyword</var>=<var>value</var></tt> settings in the
2211 <prgn>dpkg</prgn> changelog format (though there is
2212 currently only one useful <var>keyword</var>,
2216 Usual urgency values are <tt>low</tt>, <tt>medium</tt>,
2217 <tt>high</tt> and <tt>critical</tt>. They have an
2218 effect on how quickly a package will be considered for
2219 inclusion into the <tt>testing</tt> distribution, and
2220 give an indication of the importance of any fixes
2221 included in this upload.
2227 The change details may in fact be any series of lines
2228 starting with at least two spaces, but conventionally each
2229 change starts with an asterisk and a separating space and
2230 continuation lines are indented so as to bring them in
2231 line with the start of the text above. Blank lines may be
2232 used here to separate groups of changes, if desired.
2236 If this upload resolves bugs recorded in the Bug Tracking
2237 System (BTS), they may be automatically closed on the
2238 inclusion of this package into the Debian archive by
2239 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
2240 in the change details.
2243 To be precise, the string should match the following
2244 Perl regular expression:
2245 <tt>/closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i</tt>
2246 Then all of the bug numbers listed will be closed by the
2247 archive maintenance script (<prgn>katie</prgn>), or in
2248 the case of an NMU, marked as fixed.
2254 The maintainer name and email address used in the changelog
2255 should be the details of the person uploading <em>this</em>
2256 version. They are <em>not</em> necessarily those of the
2257 usual package maintainer. The information here will be
2258 copied to the <tt>Changed-By</tt> field in the
2259 <tt>.changes</tt> file, and then later used to send an
2260 acknowledgement when the upload has been installed.
2264 The <var>date</var> should be in RFC822 format
2267 This is generated by the <prgn>822-date</prgn>
2270 </footnote>; it should include the time zone specified
2271 numerically, with the time zone name or abbreviation
2272 optionally present as a comment in parentheses.
2276 The first `title' line with the package name should start
2277 at the left hand margin; the `trailer' line with the
2278 maintainer and date details should be preceded by exactly
2279 one space. The maintainer details and the date must be
2280 separated by exactly two spaces.
2283 <sect1><heading>Defining alternative changelog formats</heading>
2286 It is possible to use a different format to the standard
2287 one, by providing a parser for the format you wish to
2291 A changelog parser must not interact with the user at
2297 <sect id="srcsubstvars"><heading><tt>debian/substvars</tt>
2298 and variable substitutions </heading>
2301 When <prgn>dpkg-gencontrol</prgn>,
2302 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2303 generate control files they perform variable substitutions
2304 on their output just before writing it. Variable
2305 substitutions have the form
2306 <tt>${<var>variable-name</var>}</tt>. The optional file
2307 <tt>debian/substvars</tt> contains variable substitutions to
2308 be used; variables can also be set directly from
2309 <tt>debian/rules</tt> using the <tt>-V</tt> option to the
2310 source packaging commands, and certain predefined variables
2315 The <tt>debian/substvars</tt> file is usually generated and
2316 modified dynamically by <tt>debian/rules</tt> targets; in
2317 this case it must be removed by the <prgn>clean</prgn>
2322 See <manref name="dpkg-source" section="1"> for full
2323 details about source variable substitutions, including the
2324 format of <tt>debian/substvars</tt>.</p>
2327 <sect id="debianfiles"><heading><tt>debian/files</tt>
2331 This file is not a permanent part of the source tree; it
2332 is used while building packages to record which files are
2333 being generated. <prgn>dpkg-genchanges</prgn> uses it
2334 when it generates a <tt>.changes</tt> file.
2338 It should not exist in a shipped source package, and so it
2339 (and any backup files or temporary files such as
2343 <tt>files.new</tt> is used as a temporary file by
2344 <prgn>dpkg-gencontrol</prgn> and
2345 <prgn>dpkg-distaddfile</prgn> - they write a new
2346 version of <tt>files</tt> here before renaming it,
2347 to avoid leaving a corrupted copy if an error
2350 </footnote>) should be removed by the
2351 <prgn>clean</prgn> target. It may also be wise to
2352 ensure a fresh start by emptying or removing it at the
2353 start of the <prgn>binary</prgn> target.
2357 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2358 package, it adds an entry to <tt>debian/files</tt> for the
2359 <tt>.deb</tt> file that will be created when <prgn>dpkg-deb
2360 --build</prgn> is run for that binary package. So for most
2361 packages all that needs to be done with this file is to
2362 delete it in the <prgn>clean</prgn> target.
2366 If a package upload includes files besides the source
2367 package and any binary packages whose control files were
2368 made with <prgn>dpkg-gencontrol</prgn> then they should be
2369 placed in the parent of the package's top-level directory
2370 and <prgn>dpkg-distaddfile</prgn> should be called to add
2371 the file to the list in <tt>debian/files</tt>.</p>
2374 <sect id="restrictions"><heading>Restrictions on objects in source packages
2378 The source package may not contain any hard links
2381 This is not currently detected when building source
2382 packages, but only when extracting
2386 Hard links may be permitted at some point in the
2387 future, but would require a fair amount of
2390 </footnote>, device special files, sockets or setuid or
2394 Setgid directories are allowed.
2399 <sect id="descriptions"><heading>Descriptions of packages - the
2400 <tt>Description</tt> field </heading>
2403 The description is intended to describe the program to a user
2404 who has never met it before so that they know whether they
2405 want to install it. It should also give information about the
2406 significant dependencies and conflicts between this package
2407 and others, so that the user knows why these dependencies and
2408 conflicts have been declared.
2411 <sect1><heading>Notes about writing descriptions
2415 The single line synopsis should be kept brief - certainly
2416 under 80 characters.
2420 Do not include the package name in the synopsis line. The
2421 display software knows how to display this already, and you
2422 do not need to state it. Remember that in many situations
2423 the user may only see the synopsis line - make it as
2424 informative as you can.
2428 Do not try to continue the single line synopsis into the
2429 extended description. This will not work correctly when
2430 the full description is displayed, and makes no sense
2431 where only the summary (the single line synopsis) is
2436 The extended description should describe what the package
2437 does and how it relates to the rest of the system (in terms
2438 of, for example, which subsystem it is which part of).
2442 The description field needs to make sense to anyone, even
2443 people who have no idea about any of the things the
2447 The blurb that comes with a program in its
2448 announcements and/or <prgn>README</prgn> files is
2449 rarely suitable for use in a description. It is
2450 usually aimed at people who are already in the
2451 community where the package is used.
2457 Put important information first, both in the synopsis and
2458 extended description. Sometimes only the first part of the
2459 synopsis or of the description will be displayed. You can
2460 assume that there will usually be a way to see the whole
2461 extended description.
2465 You may include information about dependencies and so forth
2466 in the extended description, if you wish.
2470 Do not use tab characters. Their effect is not predictable.
2478 <chapt id="maintainerscripts"><heading>Package maintainer scripts
2479 and installation procedure
2482 <sect><heading>Introduction to package maintainer scripts
2486 It is possible to supply scripts as part of a package which
2487 the package management system will run for you when your
2488 package is installed, upgraded or removed.
2492 These scripts are the files <tt>preinst</tt>,
2493 <tt>postinst</tt>, <tt>prerm</tt> and <tt>postrm</tt> in the
2494 control area of the package. They must be proper executable
2495 files; if they are scripts (which is recommended), they must
2496 start with the usual <tt>#!</tt> convention. They should be
2497 readable and executable by anyone, and not world-writable.
2501 The package management system looks at the exit status from
2502 these scripts. It is important that they exit with a
2503 non-zero status if there is an error, so that the package
2504 management system can stop its processing. For shell
2505 scripts this means that you <em>almost always</em> need to
2506 use <tt>set -e</tt> (this is usually true when writing shell
2507 scripts, in fact). It is also important, of course, that
2508 they don't exit with a non-zero status if everything went
2513 When a package is upgraded a combination of the scripts from
2514 the old and new packages is called during the upgrade
2515 procedure. If your scripts are going to be at all
2516 complicated you need to be aware of this, and may need to
2517 check the arguments to your scripts.
2521 Broadly speaking the <prgn>preinst</prgn> is called before
2522 (a particular version of) a package is installed, and the
2523 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
2524 before (a version of) a package is removed and the
2525 <prgn>postrm</prgn> afterwards.
2529 Programs called from maintainer scripts should not normally
2530 have a path prepended to them. Before installation is
2531 started, the package management system checks to see if the
2532 programs <prgn>ldconfig</prgn>,
2533 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
2534 and <prgn>update-rc.d</prgn> can be found via the
2535 <tt>PATH</tt> environment variable. Those programs, and any
2536 other program that one would expect to be on the
2537 <tt>PATH</tt>, should thus be invoked without an absolute
2538 pathname. Maintainer scripts should also not reset the
2539 <tt>PATH</tt>, though they might choose to modify it by
2540 prepending or appending package-specific directories. These
2541 considerations really apply to all shell scripts.</p>
2545 <heading>Maintainer scripts Idempotency</heading>
2548 It is necessary for the error recovery procedures that the
2549 scripts be idempotent. This means that if it is run
2550 successfully, and then it is called again, it doesn't bomb
2551 out or cause any harm, but just ensures that everything is
2552 the way it ought to be. If the first call failed, or
2553 aborted half way through for some reason, the second call
2554 should merely do the things that were left undone the first
2555 time, if any, and exit with a success status if everything
2559 This is so that if an error occurs, the user interrupts
2560 <prgn>dpkg</prgn> or some other unforeseen circumstance
2561 happens you don't leave the user with a badly-broken
2562 package when <prgn>dpkg</prgn> attempts to repeat the
2570 <heading>Controlling terminal for maintainer scripts</heading>
2573 The maintainer scripts are guaranteed to run with a
2574 controlling terminal and can interact with the user.
2575 If they need to prompt for passwords, do full-screen
2576 interaction or something similar you should do these
2577 things to and from <tt>/dev/tty</tt>, since
2578 <prgn>dpkg</prgn> will at some point redirect scripts'
2579 standard input and output so that it can log the
2580 installation process. Likewise, because these scripts
2581 may be executed with standard output redirected into a
2582 pipe for logging purposes, Perl scripts should set
2583 unbuffered output by setting <tt>$|=1</tt> so that the
2584 output is printed immediately rather than being
2589 Each script should return a zero exit status for
2590 success, or a nonzero one for failure.
2594 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
2599 <list compact="compact">
2601 <p><var>new-preinst</var> <tt>install</tt></p>
2604 <p><var>new-preinst</var> <tt>install</tt>
2605 <var>old-version</var></p>
2608 <p><var>new-preinst</var> <tt>upgrade</tt>
2609 <var>old-version</var></p>
2612 <p><var>old-preinst</var> <tt>abort-upgrade</tt>
2613 <var>new-version</var>
2619 <list compact="compact">
2621 <p><var>postinst</var> <tt>configure</tt>
2622 <var>most-recently-configured-version</var></p>
2625 <p><var>old-postinst</var> <tt>abort-upgrade</tt>
2626 <var>new-version</var></p>
2629 <p><var>conflictor's-postinst</var> <tt>abort-remove</tt>
2630 <tt>in-favour</tt> <var>package</var>
2631 <var>new-version</var></p>
2635 <var>deconfigured's-postinst</var>
2636 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
2637 <var>failed-install-package</var> <var>version</var>
2638 <tt>removing</tt> <var>conflicting-package</var>
2645 <list compact="compact">
2647 <p><var>prerm</var> <tt>remove</tt></p>
2650 <p><var>old-prerm</var> <tt>upgrade</tt>
2651 <var>new-version</var></p>
2654 <p><var>new-prerm</var> <tt>failed-upgrade</tt>
2655 <var>old-version</var></p>
2658 <p><var>conflictor's-prerm</var> <tt>remove</tt>
2659 <tt>in-favour</tt> <var>package</var>
2660 <var>new-version</var></p>
2664 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
2665 <tt>in-favour</tt> <var>package-being-installed</var>
2666 <var>version</var> <tt>removing</tt>
2667 <var>conflicting-package</var>
2674 <list compact="compact">
2676 <p><var>postrm</var> <tt>remove</tt></p>
2679 <p><var>postrm</var> <tt>purge</tt></p>
2683 <var>old-postrm</var> <tt>upgrade</tt>
2684 <var>new-version</var></p>
2687 <p><var>new-postrm</var> <tt>failed-upgrade</tt>
2688 <var>old-version</var></p>
2691 <p><var>new-postrm</var> <tt>abort-install</tt></p>
2694 <p><var>new-postrm</var> <tt>abort-install</tt>
2695 <var>old-version</var></p>
2698 <p><var>new-postrm</var> <tt>abort-upgrade</tt>
2699 <var>old-version</var></p>
2703 <var>disappearer's-postrm</var> <tt>disappear</tt>
2704 <var>overwriter</var>
2705 <var>overwriter-version</var></p></item>
2710 <sect id="unpackphase"><heading>Details of unpack phase of
2711 installation or upgrade
2715 The procedure on installation/upgrade/overwrite/disappear
2716 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
2717 stage of <tt>dpkg --install</tt>) is as follows. In each
2718 case, if a major error occurs (unless listed below) the
2719 actions are, in general, run backwards - this means that the
2720 maintainer scripts are run with different arguments in
2721 reverse order. These are the `error unwind' calls listed
2729 <p>If a version of the package is already
2732 <var>old-prerm</var> upgrade <var>new-version</var>
2737 If the script runs but exits with a non-zero
2738 exit status, <prgn>dpkg</prgn> will attempt:
2740 <var>new-prerm</var> failed-upgrade <var>old-version</var>
2742 Error unwind, for both the above cases:
2744 <var>old-postinst</var> abort-upgrade <var>new-version</var>
2752 <p>If a `conflicting' package is being removed at the same time:
2756 If any packages depended on that conflicting
2757 package and <tt>--auto-deconfigure</tt> is
2758 specified, call, for each such package:
2760 <var>deconfigured's-prerm</var> deconfigure \
2761 in-favour <var>package-being-installed</var> <var>version</var> \
2762 removing <var>conflicting-package</var> <var>version</var>
2766 <var>deconfigured's-postinst</var> abort-deconfigure \
2767 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
2768 removing <var>conflicting-package</var> <var>version</var>
2770 The deconfigured packages are marked as
2771 requiring configuration, so that if
2772 <tt>--install</tt> is used they will be
2773 configured again if possible.</p>
2776 <p>To prepare for removal of the conflicting package, call:
2778 <var>conflictor's-prerm</var> remove in-favour <var>package</var> <var>new-version</var>
2782 <var>conflictor's-postinst</var> abort-remove \
2783 in-favour <var>package</var> <var>new-version</var>
2794 <p>If the package is being upgraded, call:
2796 <var>new-preinst</var> upgrade <var>old-version</var>
2801 Otherwise, if the package had some configuration
2802 files from a previous version installed (i.e., it
2803 is in the `configuration files only' state):
2805 <var>new-preinst</var> install <var>old-version</var>
2809 <p>Otherwise (i.e., the package was completely purged):
2811 <var>new-preinst</var> install
2813 Error unwind actions, respectively:
2815 <var>new-postrm</var> abort-upgrade <var>old-version</var>
2816 <var>new-postrm</var> abort-install <var>old-version</var>
2817 <var>new-postrm</var> abort-install
2827 The new package's files are unpacked, overwriting any
2828 that may be on the system already, for example any
2829 from the old version of the same package or from
2830 another package. Backups of the old files are kept
2831 temporarily, and if anything goes wrong the package
2832 management system will attempt to put them back as
2833 part of the error unwind.
2837 It is an error for a package to contains files which
2838 are on the system in another package, unless
2839 <tt>Replaces</tt> is used (see <ref id="replaces">).
2841 The following paragraph is not currently the case:
2842 Currently the <tt>- - force-overwrite</tt> flag is
2843 enabled, downgrading it to a warning, but this may not
2849 It is a more serious error for a package to contain a
2850 plain file or other kind of non-directory where another
2851 package has a directory (again, unless
2852 <tt>Replaces</tt> is used). This error can be
2853 overridden if desired using
2854 <tt>--force-overwrite-dir</tt>, but this is not
2859 Packages which overwrite each other's files produce
2860 behavior which, though deterministic, is hard for the
2861 system administrator to understand. It can easily
2862 lead to `missing' programs if, for example, a package
2863 is installed which overwrites a file from another
2864 package, and is then removed again.
2867 Part of the problem is due to what is arguably a
2868 bug in <prgn>dpkg</prgn>.
2874 A directory will never be replaced by a symbolic link
2875 to a directory or vice versa; instead, the existing
2876 state (symlink or not) will be left alone and
2877 <prgn>dpkg</prgn> will follow the symlink if there is
2885 <p>If the package is being upgraded, call
2887 <var>old-postrm</var> upgrade <var>new-version</var>
2891 <p>If this fails, <prgn>dpkg</prgn> will attempt:
2893 <var>new-postrm</var> failed-upgrade <var>old-version</var>
2895 Error unwind, for both cases:
2897 <var>old-preinst</var> abort-upgrade <var>new-version</var>
2903 This is the point of no return - if
2904 <prgn>dpkg</prgn> gets this far, it won't back off
2905 past this point if an error occurs. This will
2906 leave the package in a fairly bad state, which
2907 will require a successful re-installation to clear
2908 up, but it's when <prgn>dpkg</prgn> starts doing
2909 things that are irreversible.
2914 Any files which were in the old version of the package
2915 but not in the new are removed.</p>
2918 <p>The new file list replaces the old.</p>
2921 <p>The new maintainer scripts replace the old.</p>
2925 <p>Any packages all of whose files have been overwritten during the
2926 installation, and which aren't required for
2927 dependencies, are considered to have been removed.
2928 For each such package
2931 <p><prgn>dpkg</prgn> calls:
2933 <var>disappearer's-postrm</var> disappear \
2934 <var>overwriter</var> <var>overwriter-version</var>
2939 <p>The package's maintainer scripts are removed.
2944 It is noted in the status database as being in a
2945 sane state, namely not installed (any conffiles
2946 it may have are ignored, rather than being
2947 removed by <prgn>dpkg</prgn>). Note that
2948 disappearing packages do not have their prerm
2949 called, because <prgn>dpkg</prgn> doesn't know
2950 in advance that the package is going to
2959 Any files in the package we're unpacking that are also
2960 listed in the file lists of other packages are removed
2961 from those lists. (This will lobotomize the file list
2962 of the `conflicting' package if there is one.)
2967 The backup files made during installation, above, are
2974 The new package's status is now sane, and recorded as
2979 Here is another point of no return - if the
2980 conflicting package's removal fails we do not unwind
2981 the rest of the installation; the conflicting package
2982 is left in a half-removed limbo.
2988 If there was a conflicting package we go and do the
2989 removal actions (described below), starting with the
2990 removal of the conflicting package's files (any that
2991 are also in the package being installed have already
2992 been removed from the conflicting package's file list,
2993 and so do not get removed now).
3000 <sect><heading>Details of configuration</heading>
3003 When we configure a package (this happens with <tt>dpkg
3004 --install</tt>, or with <tt>--configure</tt>), we first
3005 update any <tt>conffile</tt>s and then call:
3007 <var>postinst</var> configure <var>most-recently-configured-version</var>
3012 No attempt is made to unwind after errors during
3017 If there is no most recently configured version
3018 <prgn>dpkg</prgn> will pass a null argument; older versions
3019 of dpkg may pass <tt><unknown></tt> (including the
3020 angle brackets) in this case. Even older ones do not pass a
3021 second argument at all, under any circumstances.
3025 <sect><heading>Details of removal and/or configuration purging
3033 <var>prerm</var> remove
3039 The package's files are removed (except <tt>conffile</tt>s).
3044 <var>postrm</var> remove
3049 All the maintainer scripts except the <tt>postrm</tt>
3054 If we aren't purging the package we stop here. Note
3055 that packages which have no <tt>postrm</tt> and no
3056 <tt>conffile</tt>s are automatically purged when
3057 removed, as there is no difference except for the
3058 <prgn>dpkg</prgn> status.</p>
3062 The conffiles and any backup files (<tt>~</tt>-files,
3063 <tt>#*#</tt> files, <tt>%</tt>-files,
3064 <tt>.dpkg-{old,new,tmp}</tt>, etc.) are removed.</p>
3068 <var>postrm</var> purge
3072 <p>The package's file list is removed.</p>
3075 No attempt is made to unwind after errors during
3082 <chapt id="relationships"><heading>Declaring relationships between
3086 Packages can declare in their control file that they have
3087 certain relationships to other packages - for example, that
3088 they may not be installed at the same time as certain other
3089 packages, and/or that they depend on the presence of others,
3090 or that they should overwrite files in certain other packages
3095 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
3096 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3097 <tt>Conflicts</tt>, <tt>Provides</tt> and <tt>Replaces</tt>
3098 control file fields.
3102 Source packages may declare relationships to binary packages,
3103 saying that they require certain binary packages to be
3104 installed or absent at the time of building the package.
3108 This is done using the <tt>Build-Depends</tt>,
3109 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
3110 <tt>Build-Conflicts-Indep</tt> control file fields.
3113 <sect id="depsyntax"><heading>Syntax of relationship fields
3117 These fields all have a uniform syntax. They are a list of
3118 package names separated by commas.
3122 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3123 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3124 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3125 control file fields of the package, which declare
3126 dependencies on other packages, the package names listed may
3127 also include lists of alternative package names, separated
3128 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
3129 if any one of the alternative packages is installed, that
3130 part of the dependency is considered to be satisfied.
3134 All of the fields except for <tt>Provides</tt> may restrict
3135 their applicability to particular versions of each named
3136 package. This is done in parentheses after each individual
3137 package name; the parentheses should contain a relation from
3138 the list below followed by a version number, in the format
3139 described in <ref id="versions">.
3143 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3144 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3145 strictly earlier, earlier or equal, exactly equal, later or
3146 equal and strictly later, respectively. The deprecated
3147 forms <tt><</tt> and <tt>></tt> were used to mean
3148 earlier/later or equal, rather than strictly earlier/later,
3149 so they should not appear in new packages (though
3150 <prgn>dpkg</prgn> still supports them).
3154 Whitespace may appear at any point in the version
3155 specification subject to the rules in <ref
3156 id="controlsyntax">, and must appear where it's necessary to
3157 disambiguate; it is not otherwise significant. For
3158 consistency and in case of future changes to
3159 <prgn>dpkg</prgn> it is recommended that a single space be
3160 used after a version relationship and before a version
3161 number; it is also conventional to put a single space after
3162 each comma, on either side of each vertical bar, and before
3163 each open parenthesis.
3167 For example, a list of dependencies might appear as:
3171 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
3176 All fields that specify build-time relationships
3177 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3178 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3179 may be restricted to a certain set of architectures. This
3180 is indicated in brackets after each individual package name and
3181 the optional version specification. The brackets enclose a
3182 list of Debian architecture names separated by whitespace.
3183 Exclamation marks may be prepended to each of the names.
3184 (It is not permitted for some names to be prepended with
3185 exclamation marks and others not.) If the current Debian
3186 host architecture is not in this list and there are no
3187 exclamation marks in the list, or it is in the list with a
3188 prepended exclamation mark, the package name and the
3189 associated version specification are ignored completely for
3190 the purposes of defining the relationships.
3197 Build-Depends-Indep: texinfo
3198 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3199 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3205 <heading>Binary Dependencies - <tt>Depends</tt>,
3206 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3207 <tt>Pre-Depends</tt>
3211 These five fields are used to declare a dependency
3212 relationship by one package on another. They appear in the
3213 depending package's control file.
3217 A <tt>Depends</tt> field takes effect <em>only</em> when a
3218 package is to be configured. It does not prevent a package
3219 being on the system in an unconfigured state while its
3220 dependencies are unsatisfied, and it is possible to replace
3221 a package whose dependencies are satisfied and which is
3222 properly installed with a different version whose
3223 dependencies are not and cannot be satisfied; when this is
3224 done the depending package will be left unconfigured (since
3225 attempts to configure it will give errors) and will not
3226 function properly. If it is necessary, a
3227 <tt>Pre-Depends</tt> field can be used, which has a partial
3228 effect even when a package is being unpacked, as explained
3229 in detail below. (The other three dependency fields,
3230 <tt>Recommends</tt>, <tt>Suggests</tt> and
3231 <tt>Enhances</tt>, are only used by the various front-ends
3232 to <prgn>dpkg</prgn> such as <prgn>dselect</prgn>.)
3236 For this reason packages in an installation run are usually
3237 all unpacked first and all configured later; this gives
3238 later versions of packages with dependencies on later
3239 versions of other packages the opportunity to have their
3240 dependencies satisfied.
3244 The <tt>Depends</tt> field thus allows package maintainers
3245 to impose an order in which packages should be configured.
3249 The meaning of the five dependency fields is as follows:
3251 <tag><tt>Depends</tt></tag>
3255 This declares an absolute dependency. A package will
3256 not be configured unless all of the packages listed in
3257 its <tt>Depends</tt> field have been correctly
3262 The <tt>Depends</tt> field should be used if the
3263 depended-on package is required for the depending
3264 package to provide a significant amount of
3268 The <tt>Depends</tt> field should also be used if the
3269 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
3270 <prgn>postrm</prgn> scripts require the package to be
3271 present in order to run. Note, however, that the
3272 <prgn>postrm</prgn> cannot rely on any non-essential
3273 packages to be present during the <tt>purge</tt>
3277 <tag><tt>Recommends</tt></tag>
3279 <p>This declares a strong, but not absolute, dependency.
3283 The <tt>Recommends</tt> field should list packages
3284 that would be found together with this one in all but
3285 unusual installations.</p>
3288 <tag><tt>Suggests</tt></tag>
3292 This is used to declare that one package may be more
3293 useful with one or more others. Using this field
3294 tells the packaging system and the user that the
3295 listed packages are related to this one and can
3296 perhaps enhance its usefulness, but that installing
3297 this one without them is perfectly reasonable.
3301 <tag><tt>Enhances</tt></tag>
3304 This field is similar to Suggests but works in the
3305 opposite direction. It is used to declare that a
3306 package can enhance the functionality of another
3311 <tag><tt>Pre-Depends</tt></tag>
3315 This field is like <tt>Depends</tt>, except that it
3316 also forces <prgn>dpkg</prgn> to complete installation
3317 of the packages named before even starting the
3318 installation of the package which declares the
3319 pre-dependency, as follows:
3323 When a package declaring a pre-dependency is about to
3324 be <em>unpacked</em> the pre-dependency can be
3325 satisfied if the depended-on package is either fully
3326 configured, <em>or even if</em> the depended-on
3327 package(s) are only unpacked or half-configured,
3328 provided that they have been configured correctly at
3329 some point in the past (and not removed or partially
3330 removed since). In this case, both the
3331 previously-configured and currently unpacked or
3332 half-configured versions must satisfy any version
3333 clause in the <tt>Pre-Depends</tt> field.
3337 When the package declaring a pre-dependency is about
3338 to be <em>configured</em>, the pre-dependency will be
3339 treated as a normal <tt>Depends</tt>, that is, it will
3340 be considered satisfied only if the depended-on
3341 package has been correctly configured.
3345 <tt>Pre-Depends</tt> should be used sparingly,
3346 preferably only by packages whose premature upgrade or
3347 installation would hamper the ability of the system to
3348 continue with any upgrade that might be in progress.
3352 <tt>Pre-Depends</tt> are also required if the
3353 <prgn>preinst</prgn> script depends on the named
3354 package. It is best to avoid this situation if
3360 When selecting which level of dependency to use you should
3361 consider how important the depended-on package is to the
3362 functionality of the one declaring the dependency. Some
3363 packages are composed of components of varying degrees of
3364 importance. Such a package should list using
3365 <tt>Depends</tt> the package(s) which are required by the
3366 more important components. The other components'
3367 requirements may be mentioned as Suggestions or
3368 Recommendations, as appropriate to the components' relative
3373 <sect id="conflicts"><heading>Conflicting binary packages -
3374 <tt>Conflicts</tt></heading>
3377 When one binary package declares a conflict with another
3378 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
3379 refuse to allow them to be installed on the system at the
3384 If one package is to be installed, the other must be removed
3385 first - if the package being installed is marked as
3386 replacing (see <ref id="replaces">) the one on the system,
3387 or the one on the system is marked as deselected, or both
3388 packages are marked <tt>Essential</tt>, then
3389 <prgn>dpkg</prgn> will automatically remove the package
3390 which is causing the conflict, otherwise it will halt the
3391 installation of the new package with an error. This
3392 mechanism is specifically designed to produce an error when
3393 the installed package is <tt>Essential</tt>, but the new
3398 A package will not cause a conflict merely because its
3399 configuration files are still installed; it must be at least
3404 A special exception is made for packages which declare a
3405 conflict with their own package name, or with a virtual
3406 package which they provide (see below): this does not
3407 prevent their installation, and allows a package to conflict
3408 with others providing a replacement for it. You use this
3409 feature when you want the package in question to be the only
3410 package providing some feature.
3414 A <tt>Conflicts</tt> entry should almost never have an
3415 `earlier than' version clause. This would prevent
3416 <prgn>dpkg</prgn> from upgrading or installing the package
3417 which declared such a conflict until the upgrade or removal
3418 of the conflicted-with package had been completed.
3422 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
3426 As well as the names of actual (`concrete') packages, the
3427 package relationship fields <tt>Depends</tt>,
3428 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3429 <tt>Pre-Depends</tt>, <tt>Conflicts</tt>,
3430 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3431 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
3432 may mention `virtual packages'.
3436 A <em>virtual package</em> is one which appears in the
3437 <tt>Provides</tt> control file field of another package.
3438 The effect is as if the package(s) which provide a
3439 particular virtual package name had been listed by name
3440 everywhere the virtual package name appears.
3444 If there are both a real and a virtual package of the same
3445 name then the dependency may be satisfied (or the conflict
3446 caused) by either the real package or any of the virtual
3447 packages which provide it. This is so that, for example,
3453 and someone else releases an enhanced version of the
3454 <tt>bar</tt> package (for example, a non-US variant), they
3460 and the <tt>bar-plus</tt> package will now also satisfy the
3461 dependency for the <tt>foo</tt> package.
3465 If a dependency or a conflict has a version number attached
3466 then only real packages will be considered to see whether
3467 the relationship is satisfied (or the prohibition violated,
3468 for a conflict) - it is assumed that a real package which
3469 provides the virtual package is not of the `right' version.
3470 So, a <tt>Provides</tt> field may not contain version
3471 numbers, and the version number of the concrete package
3472 which provides a particular virtual package will not be
3473 looked at when considering a dependency on or conflict with
3474 the virtual package name.
3478 It is likely that the ability will be added in a future
3479 release of <prgn>dpkg</prgn> to specify a version number for
3480 each virtual package it provides. This feature is not yet
3481 present, however, and is expected to be used only
3486 If you want to specify which of a set of real packages
3487 should be the default to satisfy a particular dependency on
3488 a virtual package, you should list the real package as an
3489 alternative before the virtual one.
3494 <sect id="replaces"><heading>Overwriting files and replacing
3495 packages - <tt>Replaces</tt></heading>
3498 The <tt>Replaces</tt> control file field has two distinct
3499 purposes, which come into play in different situations.
3502 <sect1><heading>Overwriting files in other packages</heading>
3505 Firstly, as mentioned before, it is usually an error for a
3506 package to contain files which are on the system in
3511 However, if the overwriting package declares that it
3512 <tt>Replaces</tt> the one containing the file being
3513 overwritten, then <prgn>dpkg</prgn> will replace the file
3514 from the old package with that from the new. The file
3515 will no longer be listed as `owned' by the old package.
3519 If a package is completely replaced in this way, so that
3520 <prgn>dpkg</prgn> does not know of any files it still
3521 contains, it is considered to have `disappeared'. It will
3522 be marked as not wanted on the system (selected for
3523 removal) and not installed. Any <tt>conffile</tt>s
3524 details noted for the package will be ignored, as they
3525 will have been taken over by the overwriting package. The
3526 package's <prgn>postrm</prgn> script will be run with a
3527 special argument to allow the package to do any final
3528 cleanup required. See <ref id="mscriptsinstact">.
3532 If an installed package, <tt>foo</tt> say, declares that
3533 it replaces another, <tt>bar</tt>, and an attempt is made
3534 to install <tt>bar</tt>, <prgn>dpkg</prgn> will discard
3535 files in the <tt>bar</tt> package which would overwrite
3536 those already present in <tt>foo</tt>. This is so that
3537 you can install an older version of a package without
3542 For this usage of <tt>Replaces</tt>, virtual packages (see
3543 <ref id="virtual">) are not considered when looking at a
3544 <tt>Replaces</tt> field - the packages declared as being
3545 replaced must be mentioned by their real names.
3549 Furthermore, this usage of <tt>Replaces</tt> only takes
3550 effect when both packages are at least partially on the
3551 system at once, so that it can only happen if they do not
3552 conflict or if the conflict has been overridden.
3557 <sect1><heading>Replacing whole packages, forcing their
3561 Secondly, <tt>Replaces</tt> allows the packaging system to
3562 resolve which package should be removed when there is a
3563 conflict - see <ref id="conflicts">. This usage only
3564 takes effect when the two packages <em>do</em> conflict,
3565 so that the two usages of this field do not interfere with
3570 In this situation, the package declared as being replaced
3571 can be a virtual package, so for example, all mail
3572 transport agents (MTAs) would have the following fields in
3573 their control files:
3575 Provides: mail-transport-agent
3576 Conflicts: mail-transport-agent
3577 Replaces: mail-transport-agent
3579 ensuring that only one MTA can be installed at any one
3584 <sect><heading>Relationships between source and binary packages -
3585 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3586 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
3590 A source package may declare a dependency or a conflict on a
3591 binary package, indicating which packages are required to be
3592 present on the system in order to build the binary packages
3593 from the source package. This is done with the control file
3594 fields <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3595 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>.
3596 The dependencies and conflicts they define must be satisfied
3597 (as defined earlier for binary packages) in order to invoke
3598 the targets in <tt>debian/rules</tt>, as follows:
3601 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
3604 The <tt>Build-Depends</tt> and
3605 <tt>Build-Conflicts</tt> fields must be satisfied when
3606 any of the following targets is invoked:
3607 <tt>build</tt>, <tt>binary</tt>, <tt>binary-arch</tt>
3608 and <tt>binary-indep</tt>.
3611 <tag><tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts-Indep</tt></tag>
3614 The <tt>Build-Depends-Indep</tt> and
3615 <tt>Build-Conflicts-Indep</tt> fields must be
3616 satisfied when any of the following targets is
3617 invoked: <tt>binary</tt> and <tt>binary-indep</tt>.
3628 <chapt id="conffiles"><heading>Configuration file handling
3632 This chapter has been superseded by <ref id="config files">.
3636 <chapt id="sharedlibs"><heading>Shared libraries</heading>
3639 Packages containing shared libraries must be constructed with
3640 a little care to make sure that the shared library is always
3641 available. This is especially important for packages whose
3642 shared libraries are vitally important, such as the C library
3643 (currently <tt>libc6</tt>).
3647 Firstly, the package should install the shared libraries under
3648 their normal names. For example, the <tt>libgdbmg1</tt>
3649 package should install <tt>libgdbm.so.1.7.3</tt> as
3650 <tt>/usr/lib/libgdbm.so.1.7.3</tt>. The files should not be
3651 renamed or re-linked by any <prgn>prerm</prgn> or
3652 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
3653 of renaming things safely without affecting running programs,
3654 and attempts to interfere with this are likely to lead to
3659 Secondly, the package should include the symbolic link that
3660 <prgn>ldconfig</prgn> would create for the shared libraries.
3661 For example, the <prgn>libgdbmg1</prgn> package should include
3662 a symbolic link from <tt>/usr/lib/libgdbm.so.1</tt> to
3663 <tt>libgdbm.so.1.7.3</tt>. This is needed so that the dynamic
3664 linker (for example <prgn>ld.so</prgn> or
3665 <prgn>ld-linux.so.*</prgn>) can find the library between the
3666 time that <prgn>dpkg</prgn> installs it and the time that
3667 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
3671 The package management system requires the library to be
3672 placed before the symbolic link pointing to it in the
3673 <tt>.deb</tt> file. This is so that when
3674 <prgn>dpkg</prgn> comes to install the symlink
3675 (overwriting the previous symlink pointing at an older
3676 version of the library), the new shared library is already
3677 in place. In the past, this was achieved by creating the
3678 library in the temporary packaging directory before
3679 creating the symlink. Unfortunately, this was not always
3680 effective, since the building of the tar file in the
3681 <tt>.deb</tt> depended on the behavior of the underlying
3682 file system. Some file systems (such as reiserfs) reorder
3683 the files so that the order of creation is forgotten.
3684 Starting with release <tt>1.7.0</tt>, <prgn>dpkg</prgn>
3685 will reorder the files itself as necessary when building a
3686 package. Thus it is no longer important to concern
3687 oneself with the order of file creation.
3693 Thirdly, the associated development package should contain a
3694 symlink for the shared library without a version number. For
3695 example, the <tt>libgdbmg1-dev</tt> package should include a
3696 symlink from <tt>/usr/lib/libgdbm.so</tt> to
3697 <tt>libgdbm.so.1.7.3</tt>. This symlink is needed by the
3698 linker (<prgn>ld</prgn>) when compiling packages, as it will
3699 only look for <tt>libgdbm.so</tt> when compiling dynamically.
3703 Any package installing shared libraries in one of the default
3704 library directories of the dynamic linker (which are currently
3705 <tt>/usr/lib</tt> and <tt>/lib</tt>) or a directory that is
3706 listed in <tt>/etc/ld.so.conf</tt>
3711 <item><p>/usr/X11R6/lib/Xaw3d</p></item>
3712 <item><p>/usr/local/lib</p></item>
3713 <item><p>/usr/lib/libc5-compat</p></item>
3714 <item><p>/lib/libc5-compat</p></item>
3715 <item><p>/usr/X11R6/lib</p></item>
3719 must call <prgn>ldconfig</prgn> in its <prgn>postinst</prgn>
3720 script if and only if the first argument is <tt>configure</tt>
3721 and should call it in the <prgn>postrm</prgn> script if the
3722 first argument is <tt>remove</tt>.
3726 However, <prgn>postrm</prgn> and <prgn>preinst</prgn> scripts
3727 <em>must not</em> call <prgn>ldconfig</prgn> in the case where
3728 the package is being upgraded (see <ref id="unpackphase"> for
3729 details), as <prgn>ldconfig</prgn> will see the temporary
3730 names that <prgn>dpkg</prgn> uses for the files while it is
3731 installing them and will make the shared library links point
3732 to them, just before <prgn>dpkg</prgn> continues the
3733 installation and renames the temporary files!
3737 <heading>Handling shared library dependencies - the
3738 <tt>shlibs</tt> system</heading>
3741 If a package contains a binary or library which links to a
3742 shared library, we must ensure that when the package is
3743 installed on the system, all of the libraries needed are
3744 also installed. This requirement led to the creation of the
3745 <tt>shlibs</tt> system, which is very simple in its design:
3746 any package which <em>provides</em> a shared library also
3747 provides information on the package dependencies required to
3748 ensure the presence of this library, and any package which
3749 <em>uses</em> a shared library uses this information to
3750 determine the dependencies it requires. The files which
3751 contain the mapping from shared libraries to the necessary
3752 dependency information are called <tt>shlibs</tt> files.
3756 Thus, when a package is built which contains any shared
3757 libraries, it must provide a <tt>shlibs</tt> file for other
3758 packages to use, and when a package is built which contains
3759 any shared libraries or compiled binaries, it must run
3760 <prgn>dpkg-shlibdeps</prgn> on these to determine the
3761 libraries used and hence the dependencies needed by this
3765 In the past, the shared libraries linked to were
3766 determined by calling <prgn>ldd</prgn>, but now
3767 <prgn>objdump</prgn> to do this. The only change this
3768 makes to package building is that
3769 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
3770 libraries, whereas in the past this was unnecessary.
3771 The rest of this footnote explains the advantage that
3776 We say that a binary <tt>foo</tt> <em>directly</em> uses
3777 a library <tt>libbar</tt> if it is explicitly linked
3778 with that library (that is, it uses the flag
3779 <tt>-lbar</tt> during the linking stage). Other
3780 libraries that are needed by <tt>libbar</tt> are linked
3781 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
3782 linker will load them automatically when it loads
3783 <tt>libbar</tt>. A package should needs to depend on
3784 the libraries it directly uses, and the dependencies for
3785 those libraries should automatically pull in the other
3790 Unfortunately, the <prgn>ldd</prgn> program shows both
3791 the directly and indirectly used libraries, meaning that
3792 the dependencies determined included both direct and
3793 indirect dependencies. The use of <prgn>objdump</prgn>
3794 avoids this problem by determining only the directly
3799 A good example of where this helps is the following. We
3800 could update <tt>libimlib</tt> with a new version that
3801 supports a new graphics format called dgf (but retaining
3802 the same major version number). If we used the old
3803 <prgn>ldd</prgn> method, every package that uses
3804 <tt>libimlib</tt> would need to be recompiled so it
3805 would also depend on <tt>libdgf</tt> or it wouldn't run
3806 due to missing symbols. However with the new system,
3807 packages using <tt>libimlib</tt> can rely on
3808 <tt>libimlib</tt> itself having the dependency on
3809 <tt>libdgf</tt> and so they would not need rebuilding.
3815 In the following sections, we will first describe where the
3816 various <tt>shlibs</tt> files are to be found, then how to
3817 use <prgn>dpkg-shlibdeps</prgn>, and finally the
3818 <tt>shlibs</tt> file format and how to create them if your
3819 package contains a shared library.
3823 <sect><heading>The <tt>shlibs</tt> files present on the system
3827 There are several places where <tt>shlibs</tt> files are
3828 found. The following list gives them in the order in which
3829 they are read by <prgn>dpkg-shlibdeps</prgn>. (The first
3830 one which gives the required information is used.)
3835 <tag><tt>debian/shlibs.local</tt></tag>
3838 This lists overrides for this package. Its use is
3839 described below (see <ref id="shlibslocal">).
3843 <tag><tt>/etc/dpkg/shlibs.override</tt></tag>
3846 This lists global overrides. This list is normally
3847 empty. It is maintained by the local system
3852 <tag><tt>DEBIAN/shlibs</tt> files in the `build directory'</tag>
3855 When packages are being built, any
3856 <tt>debian/shlibs</tt> files are copied into the
3857 control file area of the temporary build directory and
3858 given the name <tt>shlibs</tt>. These files give
3859 details of any shared libraries included in the
3863 An example may help here. Let us say that the
3864 source package <tt>foo</tt> generates two binary
3865 packages, <tt>libfoo2</tt> and
3866 <tt>foo-runtime</tt>. When building the binary
3867 packages, the two packages are created in the
3868 directories <tt>debian/libfoo2</tt> and
3869 <tt>debian/foo-runtime</tt> respectively.
3870 (<tt>debian/tmp</tt> could be used instead of one
3871 of these.) Since <tt>libfoo2</tt> provides the
3872 <tt>libfoo</tt> shared library, it will require a
3873 <tt>shlibs</tt> file, which will be installed in
3874 <tt>debian/libfoo2/DEBIAN/shlibs</tt>, eventually
3876 <tt>/var/lib/dpkg/info/libfoo2.shlibs</tt>. Then
3877 when <prgn>dpkg-shlibdeps</prgn> is run on the
3879 <tt>debian/foo-runtime/usr/bin/foo-prog</tt>, it
3881 <tt>debian/libfoo2/DEBIAN/shlibs</tt> file to
3882 determine whether <tt>foo-prog</tt>'s library
3883 dependencies are satisfied by any of the libraries
3884 provided by <tt>libfoo2</tt>. For this reason,
3885 <prgn>dpkg-shlibdeps</prgn> must only be run once
3886 all of the individual binary packages'
3887 <tt>shlibs</tt> files have been installed into the
3894 <tag><tt>/var/lib/dpkg/info/*.shlibs</tt></tag>
3897 These are the <tt>shlibs</tt> files corresponding to
3898 all of the packages installed on the system, and are
3899 maintained by the relevant package maintainers.
3903 <tag><tt>/etc/dpkg/shlibs.default</tt></tag>
3906 This file lists any shared libraries whose packages
3907 have failed to provide correct <tt>shlibs</tt> files.
3908 It was used when the <tt>shlibs</tt> setup was first
3909 introduced, but it is now normally empty. It is
3910 maintained by the <tt>dpkg</tt> maintainer.
3918 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
3919 <tt>shlibs</tt> files</heading>
3922 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
3923 <tt>debian/rules</tt> file. If your package contains only
3924 compiled binaries and libraries (but no scripts), you can
3925 use a command such as:
3927 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
3928 debian/tmp/usr/lib/*
3930 Otherwise, you will need to explicitly list the compiled
3931 binaries and libraries.
3934 If you are using <tt>debhelper</tt>, the
3935 <prgn>dh_shlibdeps</prgn> program will do this work for
3936 you. It will also correctly handle multi-binary
3943 This command puts the dependency information into the
3944 <tt>debian/substvars</tt> file, which is then used by
3945 <prgn>dpkg-gencontrol</prgn>. You will need to place a
3946 <tt>${shlib:Depends}</tt> variable in the <tt>Depends</tt>
3947 field in the control file for this to work.
3951 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
3952 done. If it does complain you might need to create your own
3953 <tt>debian/shlibs.local</tt> file, as explained below (see
3954 <ref id="shlibslocal">).
3958 If you have multiple binary packages, you will need to call
3959 <prgn>dpkg-shlibdeps</prgn> on each one which contains
3960 compiled libraries or binaries. In such a case, you will
3961 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
3962 utilities to specify a different <tt>substvars</tt> file.
3963 For more details on this and other options, see <manref
3964 name="dpkg-shlibdeps" section="1">.
3968 <sect id="shlibs"><heading>The <tt>shlibs</tt> File Format
3972 Each <tt>shlibs</tt> file has the same format. Lines
3973 beginning with <tt>#</tt> are considered to be commments and
3974 are ignored. Each line is of the form:
3976 <var>library-name</var> <var>soname-version-number</var> <var>dependencies ...</var>
3981 We will explain this by reference to the example of the
3982 <tt>zlib1g</tt> package, which (at the time of writing)
3983 installs the shared library <tt>/usr/lib/libz.so.1.1.3</tt>.
3987 <var>library-name</var> is the name of the shared library,
3988 in this case <tt>libz</tt>. (This must match the name part
3989 of the soname, see below.)
3993 <var>soname-version-number</var> is the version part of the
3994 soname of the library. The soname is the thing that must
3995 exactly match for the library to be recognized by the
3996 dynamic linker, and is usually of the form
3997 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
3998 example, <tt>libz.so.1</tt>.
4001 This can be determined using the command
4003 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
4007 The version part is the part which comes after
4008 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
4012 <var>dependencies</var> has the same syntax as a dependency
4013 field in a binary package control file. It should give
4014 details of which packages are required to satisfy a binary
4015 built against the version of the library contained in the
4016 package. See <ref id="depsyntax"> for details.
4020 In our example, if the first version of the <tt>zlib1g</tt>
4021 package which contained a minor number of at least
4022 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
4023 <tt>shlibs</tt> entry for this library could say:
4025 libz 1 zlib1g (>= 1:1.1.3)
4027 The version-specific dependency is to avoid warnings from
4028 the dynamic linker about using older shared libraries with
4034 <heading>Providing a <tt>shlibs</tt> file</heading>
4037 If your package provides a shared library, you should create
4038 a <tt>shlibs</tt> file following the format described above.
4039 It is usual to call this file <tt>debian/shlibs</tt> (but if
4040 you have multiple binary packages, you might want to call it
4041 <tt>debian/shlibs.<var>package</var></tt> instead). Then
4042 let <tt>debian/rules</tt> install it in the control area:
4044 install -m644 debian/shlibs debian/tmp/DEBIAN
4046 or, in the case of a multi-binary package:
4048 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
4050 An alternative way of doing this is to create the
4051 <tt>shlibs</tt> file in the control area directly from
4052 <tt>debian/rules</tt> without using a <tt>debian/shlibs</tt>
4056 This is what <prgn>dh_makeshlibs</prgn> in the
4057 <tt>debhelper</tt> suite does.
4060 since the <tt>debian/shlibs</tt> file itself is ignored by
4061 <prgn>dpkg-shlibdeps</prgn>.
4065 As <prgn>dpkg-shlibdeps</prgn> reads the
4066 <tt>DEBIAN/shlibs</tt> files in all of the binary packages
4067 being built from this source package, all of the
4068 <tt>DEBIAN/shlibs</tt> files should be installed before
4069 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
4074 <sect id="shlibslocal">
4075 <heading>Writing the <tt>debian/shlibs.local</tt> file</heading>
4078 This file is intended only as a <em>temporary</em> fix if
4079 your binaries or libraries depend on a library whose package
4080 does not yet provide a correct <tt>shlibs</tt> file.
4084 We will assume that you are trying to package a binary
4085 <tt>foo</tt>. When you try running
4086 <prgn>dpkg-shlibdeps</prgn> you get the following error
4087 message (<tt>-O</tt> displays the dependency information on
4088 <tt>stdout</tt> instead of writing it to
4089 <tt>debian/substvars</tt>, and the lines have been wrapped
4090 for ease of reading):
4092 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
4093 dpkg-shlibdeps: warning: unable to find dependency
4094 information for shared library libbar (soname 1,
4095 path /usr/lib/libbar.so.1, dependency field Depends)
4096 shlibs:Depends=libc6 (>= 2.2.2-2)
4098 You can then run <prgn>ldd</prgn> on the binary to find the
4099 full location of the library concerned:
4102 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
4103 libc.so.6 => /lib/libc.so.6 (0x40032000)
4104 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
4106 So the <prgn>foo</prgn> binary depends on the
4107 <prgn>libbar</prgn> shared library, but no package seems to
4108 provide a <tt>*.shlibs</tt> file handling
4109 <tt>libbar.so.1</tt> in <tt>/var/lib/dpkg/info/</tt>. Let's
4110 determine the package responsible:
4112 $ dpkg -S /usr/lib/libbar.so.1
4113 bar1: /usr/lib/libbar.so.1
4114 $ dpkg -s bar1 | grep Version
4117 This tells us that the <tt>bar1</tt> package, version 1.0-1,
4118 is the one we are using. Now we can file a bug against the
4119 <tt>bar1</tt> package and create our own
4120 <tt>debian/shlibs.local</tt> to locally fix the problem.
4121 Including the following line into your
4122 <tt>debian/shlibs.local</tt> file:
4124 libbar 1 bar1 (>= 1.0-1)
4126 should allow the package build to work.
4130 As soon as the maintainer of <tt>bar1</tt> provides a
4131 correct <tt>shlibs</tt> file, you should remove this line
4132 from your <tt>debian/shlibs.local</tt> file. (You should
4133 probably also then have a versioned <tt>Build-Depends</tt>
4134 on <tt>bar1</tt> to help ensure that others do not have the
4135 same problem building your package.)
4140 <chapt><heading>The Operating System</heading>
4143 <heading>File system hierarchy</heading>
4147 <heading>Linux File system Structure</heading>
4150 The location of all installed files and directories must
4151 comply with the Linux File system Hierarchy Standard
4152 (FHS). The latest version of this document can be found
4153 alongside this manual or on
4154 <url id="http://www.pathname.com/fhs/">.
4155 Specific questions about following the standard may be
4156 asked on <prgn>debian-devel</prgn>, or referred to Daniel
4157 Quinlan, the FHS coordinator, at
4158 <email>quinlan@pathname.com</email>.</p></sect1>
4162 <heading>Site-specific programs</heading>
4165 As mandated by the FHS, packages must not place any
4166 files in <tt>/usr/local</tt>, either by putting them in
4167 the file system archive to be unpacked by <prgn>dpkg</prgn>
4168 or by manipulating them in their maintainer scripts.</p>
4171 However, the package may create empty directories below
4172 <tt>/usr/local</tt> so that the system administrator knows
4173 where to place site-specific files. These directories
4174 should be removed on package removal if they are
4178 Note, that this applies only to directories <em>below</em>
4179 <tt>/usr/local</tt>, not <em>in</em>
4180 <tt>/usr/local</tt>. Packages must not create sub-directories
4181 in the directory <tt>/usr/local</tt> itself, except those listed in
4182 FHS, section 4.5. However, you may create directories
4183 below them as you wish. You must not remove any of the
4184 directories listed in 4.5, even if you created them.</p>
4187 Since <tt>/usr/local</tt> can be mounted read-only from a
4188 remote server, these directories must be created and
4189 removed by the <tt>postinst</tt> and <tt>prerm</tt>
4190 maintainer scripts. These scripts must not fail if either
4191 of these operations fail. (In the future, it will be
4192 possible to tell <prgn>dpkg</prgn> not to unpack files
4193 matching certain patterns, so that the directories can be
4194 included in the <tt>.deb</tt> packages and system
4195 administrators who do not wish these directories in
4196 /usr/local do not need to have them.)</p>
4199 For example, the <prgn>emacs</prgn> package will contain
4201 mkdir -p /usr/local/lib/emacs/site-lisp || true
4203 in the <tt>postinst</tt> script, and
4205 rmdir /usr/local/lib/emacs/site-lisp || true
4206 rmdir /usr/local/lib/emacs || true
4208 in the <tt>prerm</tt> script.</p>
4211 If you do create a directory in <tt>/usr/local</tt> for
4212 local additions to a package, you should ensure that
4213 settings in <tt>/usr/local</tt> take precedence over the
4214 equivalents in <tt>/usr</tt>.</p>
4217 However, because '/usr/local' and its contents are for
4218 exclusive use of the local administrator, a package must
4219 not rely on the presence or absence of files or
4220 directories in '/usr/local' for normal operation.</p>
4223 The <tt>/usr/local</tt> directory itself and all the
4224 subdirectories created by the package should (by default) have
4225 permissions 2775 (group-writable and set-group-id) and be
4226 owned by <tt>root.staff</tt>.</p>
4229 <heading>The system-wide mail directory</heading>
4231 The system-wide mail directory is <tt>/var/mail</tt>. This
4232 directory is part of the base system and should not owned
4233 by any particular mail agents. The use of the old
4234 location <tt>/var/spool/mail</tt> is deprecated, even
4235 though the spool may still be physically located there.
4236 To maintain partial upgrade compatibility for systems
4237 which have <tt>/var/spool/mail</tt> as their physical mail
4238 spool, packages using <tt>/var/mail</tt> must depend on
4239 either <package>libc6</package> (>= 2.1.3-13), or on
4240 <package>base-files</package> (>= 2.2.0), or on later
4241 versions of either one of these packages.
4250 <heading>Users and groups</heading>
4253 The Debian system can be configured to use either plain or
4254 shadow passwords.</p>
4257 Some user ids (UIDs) and group ids (GIDs) are reserved
4258 globally for use by certain packages. Because some packages
4259 need to include files which are owned by these users or
4260 groups, or need the ids compiled into binaries, these ids
4261 must be used on any Debian system only for the purpose for
4262 which they are allocated. This is a serious restriction, and
4263 we should avoid getting in the way of local administration
4264 policies. In particular, many sites allocate users and/or
4265 local system groups starting at 100.</p>
4268 Apart from this we should have dynamically allocated ids,
4269 which should by default be arranged in some sensible
4270 order--but the behavior should be configurable.</p>
4273 Packages other than <tt>base-passwd</tt> must not modify
4274 <tt>/etc/passwd</tt>, <tt>/etc/shadow</tt>,
4275 <tt>/etc/group</tt> or <tt>/etc/gshadow</tt>.</p>
4278 The UID and GID ranges are as follows:
4283 Globally allocated by the Debian project, the
4284 same on every Debian system. These ids will appear in
4285 the <tt>passwd</tt> and <tt>group</tt> files of all
4286 Debian systems, new ids in this range being added
4287 automatically as the <tt>base-passwd</tt> package is
4291 Packages which need a single statically allocated uid
4292 or gid should use one of these; their maintainers
4293 should ask the <tt>base-passwd</tt> maintainer for
4300 Dynamically allocated system users and groups.
4301 Packages which need a user or group, but can have this
4302 user or group allocated dynamically and differently on
4303 each system, should use `<tt>adduser --system</tt>' to
4304 create the group and/or user. <prgn>adduser</prgn>
4305 will check for the existence of the user or group, and
4306 if necessary choose an unused id based on the ranges
4307 specified in <tt>adduser.conf</tt>.</p></item>
4310 <tag>1000-29999:</tag>
4313 Dynamically allocated user accounts. By default
4314 <prgn>adduser</prgn> will choose UIDs and GIDs for
4315 user accounts in this range, though
4316 <tt>adduser.conf</tt> may be used to modify this
4320 <tag>30000-59999:</tag>
4322 <p>Reserved.</p></item>
4325 <tag>60000-64999:</tag>
4328 Globally allocated by the Debian project, but only
4329 created on demand. The ids are allocated centrally and
4330 statically, but the actual accounts are only created
4331 on users' systems on demand.</p>
4334 These ids are for packages which are obscure or which
4335 require many statically-allocated ids. These packages
4336 should check for and create the accounts in
4337 <tt>/etc/passwd</tt> or <tt>/etc/group</tt> (using
4338 <prgn>adduser</prgn> if it has this facility) if
4339 necessary. Packages which are likely to require
4340 further allocations should have a `hole' left after
4341 them in the allocation, to give them room to
4345 <tag>65000-65533:</tag>
4347 <p>Reserved.</p></item>
4352 <p>User `<tt>nobody</tt>.' The corresponding gid refers
4353 to the group `<tt>nogroup</tt>.'</p></item>
4359 <tt>(uid_t)(-1) == (gid_t)(-1)</tt>. NOT TO BE USED,
4360 because it is the error return sentinel value.</p>
4365 <sect id="sysvinit">
4366 <heading>System run levels</heading>
4369 <sect1 id="/etc/init.d">
4370 <heading>Introduction</heading>
4373 The <tt>/etc/init.d</tt> directory contains the scripts
4374 executed by <prgn>init</prgn> at boot time and when init
4375 state (or `runlevel') is changed (see <manref name="init"
4379 There are at least two different, yet functionally
4380 equivalent, ways of handling these scripts. For the sake
4381 of simplicity, this document describes only the symbolic
4382 link method. However, it must not be assumed by maintainer
4383 scripts that this method is being used, and any automated
4384 manipulation of the various runlevel behaviours by
4385 maintainer scripts must be performed using `update-rc.d'
4386 as described below and not by manually installing or
4387 removing symlinks. For information on the
4388 implementation details of the other method, implemented in
4389 the <tt>file-rc</tt> package, please refer to the
4390 documentation of that package.</p>
4393 These scripts are referenced by symbolic links in
4394 the <tt>/etc/rc<var>n</var>.d</tt> directories. When
4395 changing runlevels, <prgn>init</prgn> looks in the
4396 directory <tt>/etc/rc<var>n</var>.d</tt> for the scripts
4397 it should execute, where <var>n</var> is the runlevel that
4398 is being changed to, or `S' for the boot-up scripts.</p>
4401 The names of the links all have the form
4402 <tt>S<var>mm</var><var>script</var></tt> or
4403 <tt>K<var>mm</var><var>script</var></tt> where
4404 <var>mm</var> is a two-digit number and <var>script</var>
4405 is the name of the script (this should be the same as the
4406 name of the actual script in <tt>/etc/init.d</tt>.</p>
4409 When <prgn>init</prgn> changes runlevel first the targets
4410 of the links whose names starting with a <tt>K</tt> are
4411 executed, each with the single argument <tt>stop</tt>,
4412 followed by the scripts prefixed with an <tt>S</tt>, each
4413 with the single argument <tt>start</tt>. The <tt>K</tt>
4414 links are responsible for killing services and the
4415 <tt>S</tt> link for starting services upon entering the
4419 For example, if we are changing from runlevel 2 to
4420 runlevel 3, init will first execute all of the <tt>K</tt>
4421 prefixed scripts it finds in <tt>/etc/rc3.d</tt>, and then
4422 all of the <tt>S</tt> prefixed scripts. The links
4423 starting with <tt>K</tt> will cause the referred-to file
4424 to be executed with an argument of <tt>stop</tt>, and the
4425 <tt>S</tt> links with an argument of <tt>start</tt>.</p>
4428 The two-digit number <var>mm</var> is used to decide which
4429 order to start and stop things in--low-numbered links have
4430 their scripts run first. For example, the <tt>K20</tt>
4431 scripts will be executed before the <tt>K30</tt> scripts.
4432 This is used when a certain service must be started before
4433 another. For example, the name server <prgn>bind</prgn>
4434 might need to be started before the news server
4435 <prgn>inn</prgn> so that <prgn>inn</prgn> can set up its
4436 access lists. In this case, the script that starts
4437 <prgn>bind</prgn> would have a lower number than the
4438 script that starts <prgn>inn</prgn> so that it runs first:
4447 <heading>Writing the scripts</heading>
4450 Packages that include daemons for system services should
4451 place scripts in <tt>/etc/init.d</tt> to start or stop
4452 services at boot time or during a change of runlevel.
4453 These scripts should be named
4454 <tt>/etc/init.d/<var>package</var></tt>, and they should
4455 accept one argument, saying what to do:
4458 <tag><tt>start</tt></tag>
4459 <item><p>start the service,</p></item>
4461 <tag><tt>stop</tt></tag>
4462 <item><p>stop the service,</p></item>
4464 <tag><tt>restart</tt></tag>
4465 <item><p>stop and restart the service,</p></item>
4467 <tag><tt>reload</tt></tag>
4468 <item><p>cause the configuration of the service to be
4469 reloaded without actually stopping and restarting
4470 the service,</p></item>
4472 <tag><tt>force-reload</tt></tag> <item><p>cause the
4473 configuration to be reloaded if the service supports
4474 this, otherwise restart the service.</p></item>
4477 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
4478 <tt>force-reload</tt> options should be supported by all
4479 scripts in <tt>/etc/init.d</tt>, the <tt>reload</tt>
4480 option is optional.</p>
4483 The <tt>init.d</tt> scripts should ensure that they will
4484 behave sensibly if invoked with <tt>start</tt> when the
4485 service is already running, or with <tt>stop</tt> when it
4486 isn't, and that they don't kill unfortunately-named user
4487 processes. The best way to achieve this is usually to use
4488 <prgn>start-stop-daemon</prgn>.</p>
4491 If a service reloads its configuration automatically (as
4492 in the case of <prgn>cron</prgn>, for example), the
4493 <tt>reload</tt> option of the <tt>init.d</tt> script
4494 should behave as if the configuration has been reloaded
4498 These scripts should not fail obscurely when the
4499 configuration files remain but the package has been
4500 removed, as configuration files remain on the system after
4501 the package has been removed. Only when <prgn>dpkg</prgn>
4502 is executed with the <tt>--purge</tt> option will
4503 configuration files be removed. In particular, the init
4504 script itself is usually a configuration file (see
4505 <ref id="init.d notes">), and will remain on the system if
4506 the package is removed but not purged. Therefore, you
4507 should include a <tt>test</tt> statement at the top of the
4510 test -f <var>program-executed-later-in-script</var> || exit 0
4514 Often there are some values in the `<tt>init.d</tt>'
4515 scripts that a system administrator will frequently want
4516 to change. While the scripts are frequently conffiles,
4517 modifying them requires that the administrator merge in
4518 their changes each time the package is upgraded and the
4519 conffile changes. To ease the burden on the system
4520 administrator, such configurable values should not be
4521 placed directly in the script. Instead, they should be
4522 placed in a file in `<tt>/etc/default</tt>', which
4523 typically will have the same base name as the
4524 `<tt>init.d</tt>' script. This extra file can be sourced
4525 by the script when the script runs. It must contain only
4526 variable settings and comments.
4530 To ensure that vital configurable values are always
4531 available, the `<tt>init.d</tt>' script should set default
4532 values for each of the shell variables it uses before
4533 sourcing the <tt>/etc/default/</tt> file. Also, since the
4534 `<tt>/etc/default/</tt>' file is often a conffile, the
4535 `<tt>init.d</tt>' script must behave sensibly without
4536 failing if it is deleted.
4542 <heading>Managing the links</heading>
4545 The program <prgn>update-rc.d</prgn> is provided to make
4546 it easier for package maintainers to arrange for the
4547 proper creation and removal of
4548 <tt>/etc/rc<var>n</var>.d</tt> symbolic links, or their
4549 functional equivalent if another method is being used.
4550 This may be used by maintainers in their packages'
4551 <tt>postinst</tt> and <tt>postrm</tt> scripts.</p>
4554 You must use this script to make changes to
4555 <tt>/etc/rc<var>n</var>.d</tt> and <em>never</em> either
4556 include any <tt>/etc/rc<var>n</var>.d</tt> symbolic links
4557 in the actual archive or manually create or remove the
4558 symbolic links in maintainer scripts. (The latter will
4559 fail if an alternative method of maintaining runlevel
4560 information is being used.)</p>
4563 By default <prgn>update-rc.d</prgn> will start services in
4564 each of the multi-user state runlevels (2, 3, 4, and 5)
4565 and stop them in the halt runlevel (0), the single-user
4566 runlevel (1) and the reboot runlevel (6). The system
4567 administrator will have the opportunity to customize
4568 runlevels by either running <prgn>update-rc.d</prgn>, by
4569 simply adding, moving, or removing the symbolic links in
4570 <tt>/etc/rc<var>n</var>.d</tt> if symbolic links are being
4571 used, or by modifying <tt>/etc/runlevel.conf</tt> if the
4572 <tt>file-rc</tt> method is being used.</p>
4575 To get the default behavior for your package, put in your
4576 <tt>postinst</tt> script
4578 update-rc.d <var>package</var> defaults >/dev/null
4580 and in your <tt>postrm</tt>
4582 if [ purge = "$1" ]; then
4583 update-rc.d <var>package</var> remove >/dev/null
4588 This will use a default sequence number of 20. If it does
4589 not matter when or in which order the script is run, use
4590 this default. If it does, then you should talk to the
4591 maintainer of the <prgn>sysvinit</prgn> package or post to
4592 <tt>debian-devel</tt>, and they will help you choose a
4596 For more information about using <tt>update-rc.d</tt>,
4597 please consult its manpage <manref name="update-rc.d"
4598 section="8">.</p></sect1>
4602 <heading>Boot-time initialization</heading>
4605 There used to be another directory, <tt>/etc/rc.boot</tt>,
4606 which contained scripts which were run once per machine
4607 boot. This has been deprecated in favour of links from
4608 <tt>/etc/rcS.d</tt> to files in <tt>/etc/init.d</tt> as
4609 described in <ref id="/etc/init.d">. Packages must not
4610 place files in <tt>/etc/rc.boot</tt>.</p>
4612 <sect1 id="init.d notes">
4613 <heading>Notes</heading>
4616 <em>Do not</em> include the
4617 <tt>/etc/rc<var>n</var>.d/*</tt> symbolic links in the
4618 <tt>.deb</tt> file system archive! <em>This will cause
4619 problems!</em> You must create them with
4620 <prgn>update-rc.d</prgn>, as above.</p>
4623 <em>Do not</em> include the
4624 <tt>/etc/rc<var>n</var>.d/*</tt> symbolic links in
4625 <prgn>dpkg</prgn>'s conffiles list! <em>This will cause
4626 problems!</em> You should, however, treat the
4627 <tt>/etc/init.d</tt> scripts as configuration files,
4628 either by marking them as conffiles or managing them
4629 correctly in the maintainer scripts (see
4630 <ref id="config files">). (This is important since we want
4631 to give the local system administrator the chance to adapt
4632 the scripts to the local system--e.g., to disable a
4633 service without de-installing the package, or to specify
4634 some special command line options when starting a
4635 service--while making sure her changes aren't lost during
4636 the next package upgrade.)</p>
4640 <heading>Example</heading>
4643 The <prgn>bind</prgn> DNS (nameserver) package wants to
4644 make sure that the nameserver is running in multiuser
4645 runlevels, and is properly shut down with the system. It
4646 puts a script in <tt>/etc/init.d</tt>, naming the script
4647 appropriately <tt>bind</tt>. As you can see, the script
4648 interprets the argument <tt>reload</tt> to send the
4649 nameserver a <tt>HUP</tt> signal (causing it to reload its
4650 configuration); this way the user can say
4651 <tt>/etc/init.d/bind reload</tt> to reload the name
4652 server. The script has one configurable value, which can
4653 be used to pass parameters to the named program at
4661 # Original version by Robert Leslie
4662 # <rob@mars.org>, edited by iwj and cs
4664 test -x /usr/sbin/named || exit 0
4666 # Source defaults file.
4668 if [ -f /etc/default/bind ]; then
4675 echo -n "Starting domain name service: named"
4676 start-stop-daemon --start --quiet --exec /usr/sbin/named \
4681 echo -n "Stopping domain name service: named"
4682 start-stop-daemon --stop --quiet \
4683 --pidfile /var/run/named.pid --exec /usr/sbin/named
4687 echo -n "Restarting domain name service: named"
4688 start-stop-daemon --stop --quiet \
4689 --pidfile /var/run/named.pid --exec /usr/sbin/named
4690 start-stop-daemon --start --verbose --exec /usr/sbin/named \
4694 force-reload|reload)
4695 echo -n "Reloading configuration of domain name service: named"
4696 start-stop-daemon --stop --signal 1 --quiet \
4697 --pidfile /var/run/named.pid --exec /usr/sbin/named
4701 echo "Usage: /etc/init.d/bind {start|stop|restart|reload|force-reload}" >&2
4711 Complementing the above init script is a file
4712 '<tt>/etc/default/bind</tt>', which contains configurable
4713 parameters used by the script.
4717 # Specified parameters to pass to named. See named(8).
4718 # You may uncomment the following line, and edit to taste.
4724 Another example on which to base your <tt>/etc/init.d</tt>
4725 scripts is in <tt>/etc/init.d/skeleton</tt>.</p>
4728 If this package is happy with the default setup from
4729 <prgn>update-rc.d</prgn>, namely an ordering number of 20
4730 and having named running in all runlevels, it can say in
4731 its <tt>postinst</tt>:
4733 update-rc.d bind defaults >/dev/null
4735 And in its <tt>postrm</tt>, to remove the links when the
4738 if [ purge = "$1" ]; then
4739 update-rc.d bind remove >/dev/null
4745 <heading>Cron jobs</heading>
4748 Packages must not modify the configuration file
4749 <tt>/etc/crontab</tt>, and they must not modify the files in
4750 <tt>/var/spool/cron/crontabs</tt>.</p>
4753 If a package wants to install a job that has to be executed
4754 via cron, it should place a file with the name of the
4755 package in one of the following directories:
4761 As these directory names imply, the files within them are
4762 executed on a daily, weekly, or monthly basis,
4763 respectively. The exact times are listed in
4764 <tt>/etc/crontab</tt>.</p>
4767 All files installed in any of these directories must be
4768 scripts (shell scripts, Perl scripts, etc.) so that they can
4769 easily be modified by the local system administrator. In
4770 addition, they should be treated as configuration files.</p>
4773 If a certain job has to be executed more frequently than
4774 daily, the package should install a file
4775 <tt>/etc/cron.d/<var>package</var></tt>. This file uses
4776 the same syntax as <tt>/etc/crontab</tt> and is processed by
4777 <prgn>cron</prgn> automatically. The file must also be
4778 treated as a configuration file. (Note, that entries in the
4779 <tt>/etc/cron.d</tt> directory are not handled by
4780 <prgn>anacron</prgn>. Thus, you should only use this
4781 directory for jobs which may be skipped if the system is not
4785 The scripts or crontab entries in these directories should
4786 check if all necessary programs are installed before they
4787 try to execute them. Otherwise, problems will arise when a
4788 package was removed but not purged since configuration files
4789 are kept on the system in this situation.</p>
4793 <heading>Console messages</heading>
4796 This section describes different formats for messages
4797 written to standard output by the <tt>/etc/init.d</tt>
4798 scripts. The intent is to improve the consistency of
4799 Debian's startup and shutdown look and feel.</p>
4802 Please look very careful at the details. We want to get the
4803 messages to look exactly the same way concerning spaces,
4804 punctuation, and case of letters.</p>
4807 Here is a list of overall rules that you should use when you
4808 create output messages. They can be useful if you have a
4809 non-standard message that isn't covered in the sections
4816 Every message should cover one line, start with a
4817 capital letter and end with a period `.'.</p></item>
4822 If you want to express that the computer is working on
4823 something (performing a specific task, not starting or
4824 stopping a program), we use an ``ellipsis'', namely
4825 three dots `...'. Note that we don't insert spaces in
4826 front of or behind the dots. If the task has been
4827 completed we write `done.' and a line feed.</p></item>
4832 Design your messages as if the computer is telling you
4833 what he is doing (let him be polite :-) but don't
4834 mention ``him'' directly. For example, if you think
4837 I'm starting network daemons: nfsd mountd.
4841 Starting network daemons: nfsd mountd.
4842 </example></p></item>
4846 The following formats should be used</p>
4851 <p>when daemons get started.</p>
4854 Use this format if your script starts one or more
4855 daemons. The output should look like this (a single
4856 line, no leading spaces):
4858 Starting <description>: <daemon-1> <daemon-2> <...> <daemon-n>.
4860 The <description> should describe the subsystem
4861 the daemon or set of daemons are part of, while
4862 <daemon-1> up to <daemon-n> denote each
4863 daemon's name (typically the file name of the
4867 For example, the output of /etc/init.d/lpd would look like:
4869 Starting printer spooler: lpd.
4873 This can be achieved by saying
4875 echo -n "Starting printer spooler: lpd"
4876 start-stop-daemon --start --quiet lpd
4879 in the script. If you have more than one daemon to
4880 start, you should do the following:
4882 echo -n "Starting remote file system services:"
4883 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
4884 echo -n " mountd"; start-stop-daemon --start --quiet mountd
4885 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
4888 This makes it possible for the user to see what takes
4889 so long and when the final daemon has been
4890 started. You should be careful where to put spaces: In the
4891 example above the system administrator can easily
4892 comment out a line if he don't wants to start a
4893 specific daemon, while the displayed message still
4894 looks good.</p></item>
4898 <p>when something needs to be configured.</p>
4901 If you have to set up different parameters of the
4902 system upon boot up, you should use this format:
4904 Setting <parameter> to `<value>'.
4908 You can use the following echo statement to get the quotes right:
4910 echo "Setting DNS domainname to \`"value"'."
4914 Note that the left quotation mark (`) is different
4915 from the right (').</p></item>
4918 <p>when a daemon is stopped.</p>
4921 When you stop a daemon you should issue a message
4922 similar to the startup message, except that `Starting'
4923 is replaced with `Stopping'.</p>
4926 So stopping the printer daemon will like like this:
4928 Stopping printer spooler: lpd.
4929 </example></p></item>
4932 <p>when something is executed.</p>
4935 There are several examples where you have to run a
4936 program at system startup or shutdown to perform a
4937 specific task. For example, setting the system's clock
4938 via `netdate' or killing all processes when the system
4939 comes down. Your message should like this:
4941 Doing something very useful...done.
4943 You should print the `done.' right after the job has been completed,
4944 so that the user gets informed why he has to wait. You can get this
4947 echo -n "Doing something very useful..."
4951 in your script.</p></item>
4954 <p>when the configuration is reloaded.</p>
4957 When a daemon is forced to reload its configuration
4958 files you should use the following format:
4960 Reloading <daemon's-name> configuration...done.
4961 </example></p></item>
4964 <p>when none of the above rules apply.</p>
4967 If you have to print a message that doesn't fit into
4968 the styles described above, you can use something
4969 appropriate, but please have a look at the overall
4970 rules listed above.</p></item>
4975 <heading>Menus</heading>
4978 Menu entries should follow the current menu policy as
4979 defined in the file <ftpsite>ftp.debian.org</ftpsite> in
4980 <ftppath>/debian/doc/package-developer/menu-policy.txt.gz</ftppath>
4981 or your local mirror. In addition, it is included in the
4982 <tt>debian-policy</tt> package.
4986 The Debian <tt>menu</tt> packages provides a unique
4987 interface between packages providing applications and
4988 documents, and <em>menu programs</em> (either X window
4989 managers or text-based menu programs as
4990 <prgn>pdmenu</prgn>).</p>
4993 All packages that provide applications that need not be
4994 passed any special command line arguments for normal
4995 operation should register a menu entry for those
4996 applications, so that users of the <tt>menu</tt> package
4997 will automatically get menu entries in their window
4998 managers, as well in shells like <tt>pdmenu</tt>.</p>
5001 Please refer to the <em>Debian Menu System</em> document
5002 that comes with the <tt>menu</tt> package for information
5003 about how to register your applications and web
5009 <heading>Multimedia handlers</heading>
5012 Packages which provide the ability to view/show/play,
5013 compose, edit or print MIME types should register themselves
5014 as such following the current MIME support policy as defined
5015 in the file found on <ftpsite>ftp.debian.org</ftpsite> in
5016 <ftppath>/debian/doc/package-developer/mime-policy.txt.gz</ftppath>
5017 or your local mirror. In addition, it is included in the
5018 <tt>debian-policy</tt> package.
5022 MIME (Multipurpose Internet Mail Extensions, RFC 1521) is a
5023 mechanism for encoding files and data streams and providing
5024 meta-information about them, in particular their type (e.g.
5025 audio or video) and format (e.g. PNG, HTML, MP3).
5029 Registration of MIME type handlers allows programs like mail
5030 user agents and web browsers to to invoke these handlers to
5031 view, edit or display MIME types they don't support
5037 <heading>Keyboard configuration</heading>
5040 To achieve a consistent keyboard configuration (i.e., all
5041 applications interpret a keyboard event the same way) all
5042 programs in the Debian distribution must be configured to
5043 comply with the following guidelines.</p>
5046 Here is a list that contains certain keys and their interpretation:
5049 <tag><tt><--</tt></tag>
5050 <item><p>delete the character to the left of the cursor</p></item>
5052 <tag><tt>Delete</tt></tag>
5053 <item><p>delete the character to the right of the cursor</p></item>
5055 <tag><tt>Control+H</tt></tag>
5056 <item><p>emacs: the help prefix</p></item>
5059 The interpretation of any keyboard events should be independent
5060 of the terminal that's used, be it a virtual console, an X
5061 terminal emulator, an rlogin/telnet session, etc.</p>
5064 The following list explains how the different programs
5065 should be set up to achieve this:</p>
5068 <list compact="compact">
5069 <item><p>`<tt><--</tt>' generates KB_Backspace in
5072 <item><p>`<tt>Delete</tt>' generates KB_Delete in X.</p></item>
5076 X translations are set up to make KB_Backspace
5077 generate ASCII DEL, and to make KB_Delete generate
5078 <tt>ESC [ 3 ~</tt> (this is the vt220 escape code for
5079 the `delete character' key). This must be done by
5080 loading the resources using xrdb on all local X
5081 displays, not using the application defaults, so that
5082 the translation resources used correspond to the
5083 xmodmap settings.</p></item>
5087 The Linux console is configured to make
5088 `<tt><--</tt>' generate DEL, and `Delete' generate
5089 <tt>ESC [ 3 ~</tt> (this is the case at the
5093 X applications are configured so that Backspace
5094 deletes left, and Delete deletes right. Motif
5095 applications already work like this.</p></item>
5097 <item><p>stty erase <tt>^?</tt> .</p></item>
5100 The `xterm' terminfo entry should have <tt>ESC [ 3
5101 ~</tt> for kdch1, just like TERM=linux and
5102 TERM=vt220.</p></item>
5105 Emacs is programmed to map KB_Backspace or the `stty
5106 erase' character to delete-backward-char, and
5107 KB_Delete or kdch1 to delete-forward-char, and
5108 <tt>^H</tt> to help as always.</p></item>
5111 Other applications use the `stty erase' character and
5112 kdch1 for the two delete keys, with ASCII DEL being
5113 `delete previous character' and kdch1 being `delete
5114 character under cursor'.</p></item>
5118 This will solve the problem except for:</p>
5121 <list compact="compact">
5123 Some terminals have a <tt><--</tt> key that cannot
5124 be made to produce anything except <tt>^H</tt>. On
5125 these terminals Emacs help will be unavailable on
5126 <tt>^H</tt> (assuming that the `stty erase' character
5127 takes precedence in Emacs, and has been set
5128 correctly). M-x help or F1 (if available) can be used
5132 Some operating systems use <tt>^H</tt> for stty erase.
5133 However, modern telnet versions and all rlogin
5134 versions propagate stty settings, and almost all UNIX
5135 versions honour stty erase. Where the stty settings
5136 are not propagated correctly things can be made to
5137 work by using stty manually.</p></item>
5140 Some systems (including previous Debian versions) use
5141 xmodmap to arrange for both <tt><--</tt> and Delete
5142 to generate KB_Delete. We can change the behavior
5143 of their X clients via the same X resources that we
5144 use to do it for our own, or have our clients be
5145 configured via their resources when things are the
5146 other way around. On displays configured like this
5147 Delete will not work, but <tt><--</tt>
5151 Some operating systems have different kdch1 settings
5152 in their terminfo for xterm and others. On these
5153 systems the Delete key will not work correctly when
5154 you log in from a system conforming to our policy, but
5155 <tt><--</tt> will.</p></item>
5162 <heading>Environment variables</heading>
5165 A program must not depend on environment variables to get
5166 reasonable defaults. (That's because these environment
5167 variables would have to be set in a system-wide
5168 configuration file like /etc/profile, which is not supported
5172 If a program usually depends on environment variables for its
5173 configuration, the program should be changed to fall back to
5174 a reasonable default configuration if these environment
5175 variables are not present. If this cannot be done easily
5176 (e.g., if the source code of a non-free program is not
5177 available), the program must be replaced by a small
5178 `wrapper' shell script which sets the environment variables
5179 if they are not already defined, and calls the original program.</p>
5182 Here is an example of a wrapper script for this purpose:
5186 BAR=${BAR:-/var/lib/fubar}
5188 exec /usr/lib/foo/foo "$@"
5192 Furthermore, as <tt>/etc/profile</tt> is a configuration
5193 file of the <prgn>base-files</prgn> package, other packages must not
5194 put any environment variables or other commands into that
5199 <heading>Files</heading>
5203 <heading>Binaries</heading>
5206 Two different packages must not install programs with
5207 different functionality but with the same filenames. (The
5208 case of two programs having the same functionality but
5209 different implementations is handled via `alternatives.')
5210 If this case happens, one of the programs must be
5211 renamed. The maintainers should report this to the
5212 developers' mailing and try to find a consensus about
5213 which package will have to be renamed. If a consensus can
5214 not be reached, <em>both</em> programs must be
5218 Generally the following compilation parameters should be used:
5221 CFLAGS = -O2 -Wall # sane warning options vary between programs
5223 install -s # (or use strip on the files in debian/tmp)
5227 Note that by default all installed binaries should be stripped,
5228 either by using the <tt>-s</tt> flag to
5229 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
5230 the binaries after they have been copied into
5231 <tt>debian/tmp</tt> but before the tree is made into a
5235 The <tt>-N</tt> flag should not be used. On a.out systems
5236 it may have been useful for some very small binaries, but
5237 for ELF it has no good effect.</p>
5240 Debugging symbols are useful for error diagnosis,
5241 investigation of core dumps (which may be submitted by users
5242 in bug reports), or testing and developing the
5243 software. Therefore it is recommended to support building
5244 the package with debugging information through the following
5245 interface: If the environment variable
5246 <tt>DEB_BUILD_OPTIONS</tt> contains the string
5247 <tt>debug</tt>, compile the software with debugging
5248 information (usually this involves adding the <tt>-g</tt>
5249 flag to <tt>CFLAGS</tt>). This allows the generation of a
5250 build tree with debugging information. If the environment
5251 variable <tt>DEB_BUILD_OPTIONS</tt> contains the string
5252 <tt>nostrip</tt>, do not strip the files at installation
5253 time. This allows one to generate a package with debugging
5254 information included. The following makefile snippet is only
5255 an example of how one may test for either condition:
5258 Rationale: Building by default with -g causes more
5259 wasted CPU cycles since the information is stripped away
5260 anyway. The package can by default build without -g if
5261 it also provides a mechanism to easily be rebuilt with
5262 debugging information. This can be done by providing a
5263 "build-debug" make target, or allowing the user to
5264 specify "DEB_BUILD_OPTIONS=debug" in the environment while
5265 compiling that package.
5267 <p>Now this has several added benefits:
5271 It is actually easier to build debugging bins and
5272 libraries this way (no more editing debian/rules
5273 or similar) since it provides a documented way of
5274 getting this type of build.</p>
5278 There will be much less wasted CPU time for the
5279 autobuilders since not having debugging
5280 information (and hence also not having to strip
5281 it) will increase the speed of compiles. This
5282 skips an entire pass of the compiler.
5293 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
5294 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
5295 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
5296 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
5298 ifneq (,$(findstring debug,$(DEB_BUILD_OPTIONS)))
5301 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
5302 INSTALL_PROGRAM += -s
5306 Please note that the above example is merely informative,
5307 and is not a policy mandate. You may have to massage this
5308 example in order to make it work for your package.
5313 It is up to the package maintainer to decide what
5314 compilation options are best for the package. Certain
5315 binaries (such as computationally-intensive programs) will
5316 function better with certain flags (<tt>-O3</tt>, for
5317 example); feel free to use them. Please use good judgment
5318 here. Don't use flags for the sake of it; only use them
5319 if there is good reason to do so. Feel free to override
5320 the upstream author's ideas about which compilation
5321 options are best--they are often inappropriate for our
5322 environment.</p></sect>
5326 <heading>Libraries</heading>
5329 All libraries must have a shared version in the lib
5330 package and a static version in the lib-dev package. The
5331 shared version must be compiled with <tt>-fPIC</tt>, and
5332 the static version must not be. In other words, each
5333 <tt>*.c</tt> file will need to be compiled twice.</p>
5336 You must specify the gcc option <tt>-D_REENTRANT</tt>
5337 when building a library (either static or shared) to make
5338 the library compatible with LinuxThreads.</p>
5341 Note that all installed shared libraries should be
5344 strip --strip-unneeded <your-lib>
5346 (The option `--strip-unneeded' makes <tt>strip</tt> remove
5347 only the symbols which aren't needed for relocation
5348 processing.) Shared libraries can function perfectly well
5349 when stripped, since the symbols for dynamic linking are
5350 in a separate part of the ELF object file.</p>
5353 Note that under some circumstances it may be useful to
5354 install a shared library unstripped, for example when
5355 building a separate package to support debugging.
5359 An ever increasing number of packages are using libtool to
5360 do their linking. The latest GNU libtools (>= 1.3a) can take
5361 advantage of the metadata in the installed libtool archive
5362 files (`*.la'). The main advantage of libtool's .la files is
5363 that it allows libtool to store and subsequently access
5364 metadata with respect to the libraries it builds. libtool
5365 will search for those files, which contain a lot of useful
5366 information about a library (e.g. dependency libraries for
5367 static linking). Also, they're <em>essential</em> for
5368 programs using libltdl.
5372 Certainly libtool is fully capable of linking against shared
5373 libraries which don't have .la files, but being a mere shell
5374 script it can add considerably to the build time of a
5375 libtool using package if that shell-script has to derive all
5376 this information from first principles for each library every
5377 time it is linked. With the advent of libtool-1.4 (and to a
5378 lesser extent libtool-1.3), the .la files will also store
5379 information about inter-library dependencies which cannot
5380 necessarily be derived after the .la file is deleted.
5384 Packages that use libtool to create shared libraries should
5385 include the <em>.la</em> files in the <em>-dev</em>
5386 packages, with the exception that if the package relies on
5387 libtool's <em>libltdl</em> library, in which case the .la
5388 files must go in the run-time library package. This is a
5389 good idea in general, and especially for static linking
5394 You must make sure that you use only released versions of
5395 shared libraries to build your packages; otherwise other
5396 users will not be able to run your binaries
5397 properly. Producing source packages that depend on
5398 unreleased compilers is also usually a bad
5405 <heading>Shared libraries</heading>
5408 Packages involving shared libraries should be split up
5409 into several binary packages.</p>
5412 For a straightforward library which has a development
5413 environment and a runtime kit including just shared
5414 libraries you need to create two packages:
5415 <tt><var>libraryname</var><var>soname</var></tt>
5416 (<var>soname</var> is the shared object name of the shared
5417 library--it's the thing that has to match exactly between
5418 building an executable and running it for the dynamic
5419 linker to be able run the program; usually the
5420 <var>soname</var> is the major number of the library) and
5421 <tt><var>libraryname</var><var>soname</var>-dev</tt>.</p>
5424 If you prefer only to support one development version at a
5425 time you may name the development package
5426 <tt><var>libraryname</var>-dev</tt>; otherwise you may
5427 wish to use <prgn>dpkg</prgn>'s conflicts mechanism to
5428 ensure that the user only installs one development version
5429 at a time (after all, different development versions are
5430 likely to have the same header files in them, causing a
5431 filename clash if both are installed). Typically the
5432 development version should also have an exact version
5433 dependency on the runtime library, to make sure that
5434 compilation and linking happens correctly.</p>
5437 Packages which use the shared library should have a
5438 dependency on the name of the shared library package,
5439 <tt><var>libraryname</var><var>soname</var></tt>. When
5440 the <var>soname</var> changes you can have both versions
5441 of the library installed while moving from the old library
5445 If your package has some run-time support programs which
5446 use the shared library you must not put them in
5447 the shared library package. If you do that then you won't
5448 be able to install several versions of the shared library
5449 without getting filename clashes. Instead, either create
5450 a third package for the runtime binaries (this package
5451 might typically be named
5452 <tt><var>libraryname</var>-runtime</tt>--note the absence
5453 of the <var>soname</var> in the package name) or if the
5454 development package is small include them in there.</p>
5457 If you have several shared libraries built from the same
5458 source tree you may lump them all together into a single
5459 shared library package, provided that you change all their
5460 <var>soname</var>s at once (so that you don't get filename
5461 clashes if you try to install different versions of the
5462 combined shared libraries package).</p>
5465 You should follow the directions in the <em>Debian Packaging
5466 Manual</em> (or other documentation of the Debian
5467 packaging tools) for putting the shared library in its
5468 package, and you must include a <tt>shlibs</tt> control area
5469 file with details of the dependencies for packages which use
5473 Shared libraries should not be installed
5474 executable, since <prgn>ld.so</prgn> does not require this
5475 and trying to execute a shared library results in a core
5480 <heading>Scripts</heading>
5483 All command scripts, including the package maintainer
5484 scripts inside the package and used by <prgn>dpkg</prgn>,
5485 should have a <tt>#!</tt> line naming the shell to be used
5486 to interpret them.</p>
5489 In the case of Perl scripts this should be
5490 <tt>#!/usr/bin/perl</tt>.</p>
5493 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
5494 should almost certainly start with <tt>set -e</tt> so that
5495 errors are detected. Every script should use
5496 <tt>set -e</tt> or check the exit status of <em>every</em>
5500 The standard shell interpreter `<tt>/bin/sh</tt>' can be a
5501 symbolic link to any POSIX compatible shell, if <tt>echo
5502 -n</tt> does not generate a newline.
5505 Debian policy specifies POSIX behavior for /bin/sh, but
5506 echo -n has widespread use in the Linux community
5507 (including especially debian policy, the linux kernel
5508 source, many debian scripts, etc.). This echo -n
5509 mechanism is valid but not required under POSIX, hence
5510 this explicit addition. Also, rumour has it that this
5511 shall be mandated under the LSB anyway.
5515 specifying `<tt>/bin/sh</tt>' as interpreter should only
5516 use POSIX features. If a script requires non-POSIX
5517 features from the shell interpreter, the appropriate shell
5518 must be specified in the first line of the script (e.g.,
5519 `<tt>#!/bin/bash</tt>') and the package must depend on the
5520 package providing the shell (unless the shell package is
5521 marked `Essential', e.g., in the case of
5526 You may wish to restrict your script to POSIX features when possible so
5527 that it may use <tt>/bin/sh</tt> as its interpreter. If
5528 your script works with <prgn>ash</prgn>, it's probably
5529 POSIX compliant, but if you are in doubt, use
5530 <tt>/bin/bash</tt>.</p>
5533 Perl scripts should check for errors when making any
5534 system calls, including <tt>open</tt>, <tt>print</tt>,
5535 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.</p>
5538 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided
5539 as scripting languages. See <em>Csh Programming
5540 Considered Harmful</em>, one of the <tt>comp.unix.*</tt>
5541 FAQs. It can be found on
5542 <url id="http://language.perl.com/versus/csh.whynot">, or
5543 <url id="http://www.cpan.org/doc/FMTEYEWTK/versus/csh.whynot">
5544 or even on <ftpsite>ftp.cpan.org</ftpsite>
5545 <ftppath>/pub/perl/CPAN/doc/FMTEYEWTK/versus/csh.whynot</ftppath>.
5546 If an upstream package comes with <prgn>csh</prgn> scripts
5547 then you must make sure that they start with
5548 <tt>#!/bin/csh</tt> and make your package depend on the
5549 <prgn>c-shell</prgn> virtual package.</p>
5552 Any scripts which create files in world-writeable
5553 directories (e.g., in <tt>/tmp</tt>) must use a
5554 mechanism which will fail if a file with the same name
5558 The Debian base distribution provides the
5559 <prgn>tempfile</prgn> and <prgn>mktemp</prgn> utilities
5560 for use by scripts for this purpose.</p></sect>
5564 <heading>Symbolic links</heading>
5567 In general, symbolic links within a top-level directory
5568 should be relative, and symbolic links pointing from one
5569 top-level directory into another should be absolute. (A
5570 top-level directory is a sub-directory of the root
5574 In addition, symbolic links should be specified as short
5575 as possible, i.e., link targets like `foo/../bar' are
5579 Note that when creating a relative link using
5580 <prgn>ln</prgn> it is not necessary for the target of the
5581 link to exist relative to the working directory you're
5582 running <prgn>ln</prgn> from; nor is it necessary to
5583 change directory to the directory where the link is to be
5584 made. Simply include the string that should appear as the
5585 target of the link (this will be a pathname relative to
5586 the directory in which the link resides) as the first
5587 argument to <prgn>ln</prgn>.</p>
5590 For example, in your <prgn>Makefile</prgn> or
5591 <tt>debian/rules</tt>, do things like:
5593 ln -fs gcc $(prefix)/bin/cc
5594 ln -fs gcc debian/tmp/usr/bin/cc
5595 ln -fs ../sbin/sendmail $(prefix)/bin/runq
5596 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
5600 A symbolic link pointing to a compressed file should
5601 always have the same file extension as the referenced
5602 file. (For example, if a file `<tt>foo.gz</tt>' is
5603 referenced by a symbolic link, the filename of the link
5604 has to end with `<tt>.gz</tt>' too, as in
5605 `bar.gz.')</p></sect>
5609 <heading>Device files</heading>
5612 Packages must not include device files in the package file
5616 If a package needs any special device files that are not
5617 included in the base system, it must call
5618 <prgn>MAKEDEV</prgn> in the <tt>postinst</tt> script,
5619 after asking the user for permission to do so.</p>
5622 Packages must not remove any device files in the
5623 <tt>postrm</tt> or any other script. This is left to the
5624 system administrator.</p>
5627 Debian uses the serial devices
5628 <tt>/dev/ttyS*</tt>. Programs using the old
5629 <tt>/dev/cu*</tt> devices should be changed to use
5630 <tt>/dev/ttyS*</tt>.</p>
5633 <sect id="config files">
5634 <heading>Configuration files</heading>
5636 <heading>Definitions</heading>
5639 <tag>configuration file</tag>
5641 A file that affects the operation of program, or
5642 provides site- or host-specific information, or
5643 otherwise customizes the behavior of program.
5644 Typically, configuration files are intended to be
5645 modified by the system administrator (if needed or
5646 desired) to conform to local policy or provide more
5647 useful site-specific behavior.</p>
5650 <tag><tt>conffile</tt></tag>
5652 A file listed in a package's <tt>conffiles</tt>
5653 file, and is treated specially by <prgn>dpkg</prgn>
5654 (see the <em>Debian Packaging Manual</em>).</p>
5660 The distinction between these two is important; they are
5661 not interchangeable concepts. Almost all
5662 <tt>conffiles</tt> are configuration files, but many
5663 configuration files are not <tt>conffiles</tt>.</p>
5666 Note that a script that embeds configuration information
5667 (such as most of the files in <tt>/etc/init.d</tt> and
5668 <tt>/etc/cron.{daily,weekly,monthly}</tt>) is de-facto a
5669 configuration file and should be treated as such.</p>
5673 <heading>Location</heading>
5675 Any configuration files created or used by your package
5676 must reside in <tt>/etc</tt>. If there are several you
5677 should consider creating a subdirectory of <tt>/etc</tt>
5678 named after your package.</p>
5681 If your package creates or uses configuration files
5682 outside of <tt>/etc</tt>, and it is not feasible to modify
5683 the package to use the <tt>/etc</tt>, you should still put
5684 the files in <tt>/etc</tt> and create symbolic links to
5685 those files from the location that the package
5690 <heading>Behavior</heading>
5692 Configuration file handling must conform to the following
5696 <p>local changes must be preserved during a package
5700 <p>configuration files must be preserved when the
5701 package is removed, and only deleted when the
5702 package is purged.</p>
5707 The easy way to achieve this behavior is to make the
5708 configuration file a <tt>conffile</tt>. This is
5709 appropriate only if it is possible to distribute a default
5710 version that will work for most installations, although
5711 some system administrators may choose to modify it. This
5712 implies that the default version will be part of the
5713 package distribution, and must not be modified by the
5714 maintainer scripts during installation (or at any other
5719 In order to ensure that local changes are preserved
5720 correctly, no package may contain or make hard links to
5724 Rationale: There are two problems with hard links.
5725 The first is that some editors break the link while
5726 editing one of the files, so that the two files may
5727 unwittingly become different. The second is that
5728 <prgn>dpkg</prgn> might break the hard link while
5729 upgrading <tt>conffile</tt>s.
5735 The other way to do it is via the maintainer scripts.
5736 In this case, the configuration file must not be listed as
5737 a <tt>conffile</tt> and must not be part of the package
5738 distribution. If the existence of a file is required for
5739 the package to be sensibly configured it is the
5740 responsibility of the package maintainer to write scripts
5741 which correctly create, update, maintain and
5742 remove-on-purge the file. These scripts must be idempotent
5743 (i.e., must work correctly if <prgn>dpkg</prgn> needs to
5744 re-run them due to errors during installation or removal),
5745 must cope with all the variety of ways <prgn>dpkg</prgn>
5746 can call maintainer scripts, must not overwrite or
5747 otherwise mangle the user's configuration without asking,
5748 must not ask unnecessary questions (particularly during
5749 upgrades), and otherwise be good citizens.</p>
5752 The scripts are not required to configure every possible option for
5753 the package, but only those necessary to get the package
5754 running on a given system. Ideally the sysadmin should not
5755 have to do any configuration other than that done
5756 (semi-)automatically by the <tt>postinst</tt> script.</p>
5759 A common practice is to create a script called
5760 <tt><var>package</var>-configure</tt> and have the
5761 package's <tt>postinst</tt> call it if and only if the
5762 configuration file does not already exist. In certain
5763 cases it is useful for there to be an example or template
5764 file which the maintainer scripts use. Such files should
5765 be in <tt>/usr/share/<package></tt> or
5766 <tt>/usr/lib/<package></tt> with a symbolic link
5767 from <tt>/usr/share/doc/<package>/examples</tt>
5768 if they are examples, and should be
5769 perfectly ordinary <prgn>dpkg</prgn>-handled files
5770 (<em>not</em> <tt>conffiles</tt>).
5774 These two styles of configuration file handling must
5775 not be mixed, for that way lies madness:
5776 <prgn>dpkg</prgn> will ask about overwriting the file
5777 every time the package is upgraded.</p>
5782 <heading>Sharing configuration files</heading>
5784 Packages which specify the same file as
5785 `<tt>conffile</tt>' must be tagged as <em>conflicting</em>
5790 The maintainer scripts must not alter the conffile of
5791 <em>any</em> package, including the one the scripts belong
5795 If two or more packages use the same configuration file
5796 and it is reasonable for both to be installed at the same
5797 time, one of these packages must be defined as
5798 <em>owner</em> of the configuration file, i.e., it will be
5799 the package to list that distributes the file and lists it
5800 as a <tt>conffile</tt>. Other packages that use the
5801 configuration file must depend on the owning package if
5802 they require the configuration file to operate. If the
5803 other package will use the configuration file if present,
5804 but is capable of operating without it, no dependency need
5808 If it is desirable for two or more related packages to
5809 share a configuration file <em>and</em> for all of the
5810 related packages to be able to modify that configuration
5811 file, then the following should be done:
5815 have one of the related packages (the "core"
5816 package) manage the configuration file with
5817 maintainer scripts as described in the previous
5821 the core package should also provide a program that
5822 the other packages may use to modify the
5823 configuration file.</p>
5827 the related packages must use the provided program
5828 to make any modifications to the configuration file.
5829 They should either depend on the core package to
5830 guarantee that the configuration modifier program is
5831 available or accept gracefully that they cannot
5832 modify the configuration file if it is not.</p>
5837 Sometimes it's appropriate to create a new package which
5838 provides the basic infrastructure for the other packages
5839 and which manages the shared configuration files. (Check
5840 out the <tt>sgml-base</tt> package as an example.)</p>
5844 <heading>User configuration files ("dotfiles")</heading>
5847 Files in <tt>/etc/skel</tt> will automatically be copied
5848 into new user accounts by <prgn>adduser</prgn>. They
5849 should not be referenced there by any program.</p>
5852 Therefore, if a program needs a dotfile to exist in
5853 advance in <tt>$HOME</tt> to work sensibly, that dotfile
5854 should be installed in <tt>/etc/skel</tt> (and listed in
5855 conffiles, if it is not generated and modified dynamically
5856 by the package's installation scripts).</p>
5859 However, programs that require dotfiles in order to
5860 operate sensibly (dotfiles that they do not create
5861 themselves automatically, that is) are a bad thing, and
5862 programs should be configured by the Debian default
5863 installation as close to normal as possible.</p>
5866 Therefore, if a program in a Debian package needs to be
5867 configured in some way in order to operate sensibly that
5868 configuration should be done in a site-wide global
5869 configuration file elsewhere in <tt>/etc</tt>. Only if the
5870 program doesn't support a site-wide default configuration
5871 and the package maintainer doesn't have time to add it
5872 may a default per-user file be placed in
5873 <tt>/etc/skel</tt>.</p>
5876 <tt>/etc/skel</tt> should be as empty as we can make it.
5877 This is particularly true because there is no easy
5878 mechanism for ensuring that the appropriate dotfiles are
5879 copied into the accounts of existing users when a package
5885 <heading>Log files</heading>
5887 The traditional approach to log files has been to set up ad
5888 hoc log rotation schemes using simple shell scripts and
5889 cron. While this approach is highly customizable, it
5890 requires quite a lot of sysadmin work. Even though the
5891 original Debian system helped a little by automatically
5892 installing a system which can be used as a template, this
5893 was deemed not enough.
5897 A better scheme is to use logrotate, a GPL'd program
5898 developed by Red Hat, which centralizes log management. It
5899 has both a configuration file (<tt>/etc/logrotate.conf</tt>)
5900 and a directory where packages can drop logrotation info
5901 (<tt>/etc/logrotate.d</tt>).
5905 Log files should usually be named
5906 <tt>/var/log/<var>package</var>.log</tt>. If you have many
5907 log files, or need a separate directory for permissions
5908 reasons (<tt>/var/log</tt> is writable only by
5909 <tt>root</tt>), you should usually create a directory named
5910 <tt>/var/log/<var>package</var></tt>.</p>
5913 Log files must be rotated occasionally so
5914 that they don't grow indefinitely; the best way to do this
5915 is to drop a script into the directory
5916 <tt>/etc/logrotate.d</tt> and use the facilities provided by
5917 logrotate. Here is a good example for a logrotate config
5918 file (for more information see <manref name="logrotate"
5926 /etc/init.d/foo force-reload
5930 Which rotates all files under `/var/log/foo', saves 12
5931 compressed generations, and sends a HUP signal at the end of
5937 Log files should be removed when the package is
5938 purged (but not when it is only removed), by checking the
5939 argument to the <tt>postrm</tt> script (see the <em>Debian
5940 Packaging Manual</em> for details).</p>
5945 <heading>Permissions and owners</heading>
5948 The rules in this section are guidelines for general use.
5949 If necessary you may deviate from the details below.
5950 However, if you do so you must make sure that what is done
5951 is secure and you should try to be as consistent as possible
5952 with the rest of the system. You should probably also
5953 discuss it on <prgn>debian-devel</prgn> first.</p>
5956 Files should be owned by <tt>root.root</tt>, and made
5957 writable only by the owner and universally readable (and
5958 executable, if appropriate).</p>
5961 Directories should be mode 755 or (for group-writability)
5962 mode 2775. The ownership of the directory should be
5963 consistent with its mode--if a directory is mode 2775, it
5964 should be owned by the group that needs write access to
5968 Setuid and setgid executables should be mode 4755 or 2755
5969 respectively, and owned by the appropriate user or group.
5970 They should not be made unreadable (modes like 4711 or
5971 2711 or even 4111); doing so achieves no extra security,
5972 because anyone can find the binary in the freely available
5973 Debian package--it is merely inconvenient. For the same
5974 reason you should not restrict read or execute permissions
5975 on non-set-id executables.</p>
5978 Some setuid programs need to be restricted to particular
5979 sets of users, using file permissions. In this case they
5980 should be owned by the uid to which they are set-id, and
5981 by the group which should be allowed to execute them.
5982 They should have mode 4754; there is no point in making
5983 them unreadable to those users who must not be allowed to
5987 You must not arrange that the system administrator can only
5988 reconfigure the package to correspond to their local
5989 security policy by changing the permissions on a binary.
5990 Ordinary files installed by <prgn>dpkg</prgn> (as opposed
5991 to conffiles and other similar objects) have their
5992 permissions reset to the distributed permissions when the
5993 package is reinstalled. Instead you should consider (for
5994 example) creating a group for people allowed to use the
5995 program(s) and making any setuid executables executable
5996 only by that group.</p>
5999 If you need to create a new user or group for your package
6000 there are two possibilities. Firstly, you may need to
6001 make some files in the binary package be owned by this
6002 user or group, or you may need to compile the user or
6003 group id (rather than just the name) into the binary
6004 (though this latter should be avoided if possible, as in
6005 this case you need a statically allocated id).</p>
6008 If you need a statically allocated id, you must ask for a
6009 user or group id from the base system
6010 maintainer, and must not release the package until you
6011 have been allocated one. Once you have been allocated one
6012 you must make the package depend on a version of the base
6013 system with the id present in <tt>/etc/passwd</tt> or
6014 <tt>/etc/group</tt>, or alternatively arrange for your
6015 package to create the user or group itself with the
6016 correct id (using <tt>adduser</tt>) in its pre- or
6017 post-installation script (the latter is to be preferred if
6018 it is possible).</p>
6021 On the other hand, the program might be able to determine the
6022 uid or gid from the group name at runtime, so that a
6023 dynamic id can be used. In this case you should choose an
6024 appropriate user or group name, discussing this on
6025 <prgn>debian-devel</prgn> and checking with the base
6026 system maintainer that it is unique and that they do not
6027 wish you to use a statically allocated id instead. When
6028 this has been checked you must arrange for your package to
6029 create the user or group if necessary using
6030 <prgn>adduser</prgn> in the pre- or post-installation
6031 script (again, the latter is to be preferred if it is
6035 Note that changing the numeric value of an id associated with a name
6036 is very difficult, and involves searching the file system for all
6037 appropriate files. You need to think carefully whether a static or
6038 dynamic id is required, since changing your mind later will cause
6043 <chapt id="customized-programs">
6044 <heading>Customized programs</heading>
6046 <sect id="arch-spec">
6047 <heading>Architecture specification strings</heading>
6050 If a program needs to specify an <em>architecture specification
6051 string</em> in some place, the following format should be used:
6053 <arch>-<os>
6055 where `<arch>' is one of the following: i386, alpha, arm, m68k,
6056 powerpc, sparc and `<os>' is one of: linux, gnu. Use
6057 of <em>gnu</em> in this string is reserved for the GNU/Hurd
6058 operating system.</p>
6060 Note, that we don't want to use `<arch>-debian-linux'
6061 to apply to the rule `architecture-vendor-os' since this
6062 would make our programs incompatible to other Linux
6063 distributions. Also note, that we don't use
6064 `<arch>-unknown-linux', since the `unknown' does not
6065 look very good.</p></sect>
6069 <heading>Daemons</heading>
6072 The configuration files <tt>/etc/services</tt>,
6073 <tt>/etc/protocols</tt>, and <tt>/etc/rpc</tt> are managed
6074 by the <prgn>netbase</prgn> package and may not be modified
6075 by other packages.</p>
6078 If a package requires a new entry in one of these files, the
6079 maintainer should get in contact with the
6080 <prgn>netbase</prgn> maintainer, who will add the entries
6081 and release a new version of the <prgn>netbase</prgn>
6085 The configuration file <tt>/etc/inetd.conf</tt> must not be
6086 modified by the package's scripts except via the
6087 <prgn>update-inetd</prgn> script or the
6088 <prgn>DebianNet.pm</prgn> Perl module.</p>
6091 If a package wants to install an example entry into
6092 <tt>/etc/inetd.conf</tt>, the entry must be preceded with
6093 exactly one hash character (<tt>#</tt>). Such lines are
6094 treated as `commented out by user' by the
6095 <prgn>update-inetd</prgn> script and are not changed or
6096 activated during a package updates.</p></sect>
6100 <heading>Using pseudo-ttys and modifying wtmp, utmp and lastlog</heading>
6103 Some programs need to create pseudo-ttys. This should be done
6104 using Unix98 ptys if the C library supports it. The resulting
6105 program must not be installed setuid root, unless that
6106 is required for other functionality.
6110 The files <tt>/var/run/utmp</tt>, <tt>/var/log/wtmp</tt> and
6111 <tt>/var/log/lastlog</tt> must be installed writeable by
6112 group utmp. Programs who need to modify those files must
6113 be installed setgid utmp.
6118 <heading>Editors and pagers</heading>
6121 Some programs have the ability to launch an editor or pager
6122 program to edit or display a text document. Since there are
6123 lots of different editors and pagers available in the Debian
6124 distribution, the system administrator and each user should
6125 have the possibility to choose his/her preferred editor and
6129 In addition, every program should choose a good default
6130 editor/pager if none is selected by the user or system
6134 Thus, every program that launches an editor or pager must
6135 use the EDITOR or PAGER environment variables to determine
6136 the editor/pager the user wants to get started. If these
6137 variables are not set, the programs <tt>/usr/bin/editor</tt>
6138 and <tt>/usr/bin/pager</tt> should be used, respectively.</p>
6141 These two files are managed through `alternatives.' That is,
6142 every package providing an editor or pager must call the
6143 <prgn>update-alternatives</prgn> script to register these
6147 If it is very hard to adapt a program to make us of the
6148 EDITOR and PAGER variables, that program may be configured
6149 to use <tt>/usr/bin/sensible-editor</tt> and
6150 <tt>/usr/bin/sensible-pager</tt> as editor or pager program,
6151 respectively. These are two scripts provided in the Debian
6152 base system that check the EDITOR and PAGER variables and
6153 launch the appropriate program or fall back to
6154 <tt>/usr/bin/editor</tt> and <tt>/usr/bin/pager</tt>,
6158 A program may also use the VISUAL environment variable to
6159 determine the user's choice of editor. If it exists, it
6160 should take precedence over EDITOR. This is in fact what
6161 <tt>/usr/bin/sensible-editor</tt> does.</p>
6164 It is not required for a package to depend on
6165 `editor' and `pager', nor is it required for a package to
6166 provide such virtual packages.
6169 The Debian base system already provides an editor and
6178 <sect id="web-appl">
6179 <heading>Web servers and applications</heading>
6182 This section describes the locations and URLs that should
6183 be used by all web servers and web application in the Debian
6189 <p>Cgi-bin executable files are installed in the
6192 /usr/lib/cgi-bin/<cgi-bin-name>
6194 and should be referred to as
6196 http://localhost/cgi-bin/<cgi-bin-name>
6197 </example></p></item>
6200 <item><p>Access to html documents</p>
6203 Html documents for a package are stored in
6204 <tt>/usr/share/doc/<var>package</var></tt> but should
6205 be accessed via symlinks as
6206 <tt>/usr/doc/<var>package</var></tt><footnote> for
6207 backward compatibility, see <ref id="usrdoc"></footnote>
6208 and can be referred to as
6210 http://localhost/doc/<package>/<filename>
6211 </example></p></item>
6214 <item><p>Web Document Root</p>
6217 Web Applications should try to avoid storing files in
6218 the Web Document Root. Instead they should use the
6219 /usr/share/doc/<package> directory for documents and
6220 register the Web Application via the menu package. If
6221 access to the web-root is unavoidable then use
6225 as the Document Root. This might be just a
6226 symbolic link to the location where the sysadmin has
6227 put the real document root.</p>
6230 </enumlist></p></sect>
6233 <sect id="mail-transport-agents">
6234 <heading>Mail transport, delivery and user agents</heading>
6237 Debian packages which process electronic mail, whether
6238 mail-user-agents (MUAs) or mail-transport-agents (MTAs),
6239 must make sure that they are compatible with the
6240 configuration decisions below. Failure to do this may
6241 result in lost mail, broken <tt>From:</tt> lines, and other
6242 serious brain damage!</p>
6245 The mail spool is <tt>/var/mail</tt> and the interface
6246 to send a mail message is <tt>/usr/sbin/sendmail</tt> (as
6247 per the FHS). On older systems, the mail spool may be
6248 physically located in /var/spool/mail, but all access to the
6249 mail spool should be via the /var/mail symlink. The mail
6250 spool is part of the base system and not part of the MTA
6255 All Debian MUAs, MTAs, MDAs and other mailbox accessing
6256 programs (like IMAP daemons) must lock the mailbox in an
6257 NFS-safe way. This means that <tt>fcntl()</tt> locking must
6258 be combined with dot locking. To avoid deadlocks, a
6259 program should use <tt>fcntl()</tt> first and dot locking
6260 after this or alternatively implement the two locking
6261 methods in a non blocking way<footnote>
6263 If it is not possible to establish both locks, the
6264 system shouldn't wait for the second lock to be
6265 established, but remove the first lock, wait a (random)
6266 time, and start over locking again.</p>
6267 </footnote>. Using the functions <tt>maillock</tt> and
6268 <tt>mailunlock</tt> provided by the
6269 <tt>liblockfile*</tt><footnote>
6271 <tt>liblockfile</tt> version >>1.01</p>
6272 </footnote> packages is the recommended way to realize this.
6276 Mailboxes are generally 660 <tt><var>user</var>.mail</tt>
6277 unless the user has chosen otherwise. A MUA may remove a
6278 mailbox (unless it has nonstandard permissions) in which
6279 case the MTA or another MUA must recreate it if needed.
6280 Mailboxes must be writable by group mail.</p>
6283 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
6284 be setgid mail to do the locking mentioned above (and
6285 must obviously avoid accessing other users' mailboxes
6286 using this privilege).</p>
6289 <tt>/etc/aliases</tt> is the source file for the system mail
6290 aliases (e.g., postmaster, usenet, etc.)--it is the one
6291 which the sysadmin and <tt>postinst</tt> scripts may edit.
6292 After <tt>/etc/aliases</tt> is edited the program or human
6293 editing it must call <prgn>newaliases</prgn>. All MTA
6294 packages must come with a <prgn>newaliases</prgn> program,
6295 even if it does nothing, but older MTA packages do not do
6296 this so programs should not fail if <prgn>newaliases</prgn>
6297 cannot be found.</p>
6300 The convention of writing <tt>forward to
6301 <var>address</var></tt> in the mailbox itself is not
6302 supported. Use a <tt>.forward</tt> file instead.</p>
6305 The <prgn>rmail</prgn> program used by UUCP
6306 for incoming mail should be <tt>/usr/sbin/rmail</tt>.
6307 Likewise, <prgn>rsmtp</prgn>, for receiving
6308 batch-SMTP-over-UUCP, should be <tt>/usr/sbin/rsmtp</tt> if it
6312 If you need to know what name to use (for example) on
6313 outgoing news and mail messages which are generated locally,
6314 you should use the file <tt>/etc/mailname</tt>. It will
6315 contain the portion after the username and <tt>@</tt> (at)
6316 sign for email addresses of users on the machine (followed
6320 A package should check for the existence of this file. If
6321 it exists it should use it without comment. (An MTA's
6322 prompting configuration script may wish to prompt the user
6323 even if it finds this file exists.) If it does not exist it
6324 should prompt the user for the value and store it in
6325 <tt>/etc/mailname</tt> as well as using it in the package's
6326 configuration. The prompt should make it clear that the
6327 name will not just be used by that package. For example, in
6328 this situation the INN package says:
6330 Please enter the `mail name' of your system. This is the
6331 hostname portion of the address to be shown on outgoing
6332 news and mail messages. The default is
6333 <var>syshostname</var>, your system's host name. Mail
6334 name [`<var>syshostname</var>']:
6336 where <var>syshostname</var> is the output of <tt>hostname
6337 --fqdn</tt>.</p></sect>
6341 <heading>News system configuration</heading>
6344 All the configuration files related to the NNTP (news)
6345 servers and clients should be located under
6346 <tt>/etc/news</tt>.</p>
6349 There are some configuration issues that apply to a number
6350 of news clients and server packages on the machine. These
6354 <tag>/etc/news/organization</tag>
6355 <item><p>A string which should appear as the
6356 organization header for all messages posted
6357 by NNTP clients on the machine</p></item>
6359 <tag>/etc/news/server</tag>
6360 <item><p>Contains the FQDN of the upstream NNTP
6361 server, or localhost if the local machine is
6362 an NNTP server.</p></item>
6365 Other global files may be added as required for cross-package news
6366 configuration.</p></sect>
6370 <heading>Programs for the X Window System</heading>
6373 <em>Programs that may be configured with support for the X Window
6374 System</em> must be configured to do so and must declare any
6375 package dependencies necessary to satisfy their runtime
6376 requirements when using the X Window System, unless the package
6377 in question is of standard or higher priority, in which case
6378 X-specific binaries may be split into a separate package, or
6379 alternative versions of the package with X support may be
6385 <em>Packages which provide an X server</em> that, directly or
6386 indirectly, communicates with real input and display hardware
6387 should declare in their control data that they provide the
6388 virtual package <tt>xserver</tt>.
6391 This implements current practice, and provides an actual
6392 policy for usage of the "xserver" virtual package which
6393 appears in the virtual packages list. In a nutshell, X
6394 servers that interface directly with the display and input
6395 hardware or via another subsystem (e.g., GGI) should provide
6396 xserver. Things like Xvfb, Xnest, and Xprt should not.
6402 <em>Packages that provide a terminal emulator</em> for the X
6403 Window System which support a terminal type with a terminfo
6404 description provided in the <tt>ncurses-base</tt> package
6405 should declare in their control data that they provide the
6406 virtual package <tt>x-terminal-emulator</tt>. They should
6407 also register themselves as an alternative for
6408 <tt>/usr/bin/x-terminal-emulator</tt>, with a priority of
6413 <em>Packages that provide window managers</em> should declare in
6414 their control data that they provide the virtual package
6415 <tt>x-window-manager</tt>. They should also register themselves as an
6416 alternative for <tt>/usr/bin/x-window-manager</tt>, with a priority
6417 calculated as follows:
6419 <item>Start with a priority of 20.</item>
6420 <item>If the window manager supports the Debian menu system,
6421 add 20 points if this support is available in the
6422 package's default configuration (i.e., no
6423 configuration files belonging to the system or user
6424 have to be edited to activate the feature); if
6425 configuration files must be modified, add only 10
6427 <item>If the window manager permits the X session to be
6428 restarted using a <em>different</em> window manager
6429 (without killing the X server) in its default
6430 configuration, add 10 points; otherwise add
6436 <em>Packages that provide fonts for the X Window System</em>
6437 must do a number of things to ensure that they are both
6438 available without modification of the X or font server
6439 configuration, and that they do not corrupt files used by
6440 other font packages to register information about themselves.
6443 Fonts of any type supported by the X Window System
6444 should be be in a separate binary package from any
6445 executables, libraries, or documentation (except that
6446 specific to the fonts shipped); if a program or
6447 library is <em>unusable</em> without one or more
6448 specific fonts, the package containing the program or
6449 library should declare a dependency on the package(s)
6450 containing the font(s) it requires.
6453 BDF fonts should be converted to PCF fonts with the
6454 <tt>bdftopcf</tt> utility (available in the
6455 <tt>xutils</tt> package), <tt>gzip</tt>ped, and
6456 placed in a directory that corresponds to their
6460 100 dpi fonts should be placed in
6461 <tt>/usr/X11R6/lib/X11/fonts/100dpi/</tt>.
6464 75 dpi fonts should be placed in
6465 <tt>/usr/X11R6/lib/X11/fonts/75dpi/</tt>.
6468 Character-cell fonts, cursor fonts, and other
6469 low-resolution fonts should be placed in
6470 <tt>/usr/X11R6/lib/X11/fonts/misc/</tt>.
6475 Speedo fonts should be placed in
6476 <tt>/usr/X11R6/lib/X11/fonts/Speedo/</tt>.
6479 Type 1 fonts should be placed in
6480 <tt>/usr/X11R6/lib/X11/fonts/Type1/</tt>. If font
6481 metric files are available, they may be placed here as
6485 Subdirectories of <tt>/usr/X11R6/lib/X11/fonts/</tt>
6486 other than those listed above should be neither created nor
6487 used. (The <tt>PEX</tt> and <tt>cyrillic</tt> directories are
6488 excepted for historical reasons, but installation of files into
6489 these directories remains discouraged.)
6492 Font packages may, instead of placing files directly in
6493 the X font directories listed above, provide symbolic links in
6494 the font directory which point to the files' actual location
6495 in the filesystem. Such a location should comply with the
6499 Font packages should not contain both 75dpi and 100dpi
6500 versions of a font. If both are available, they should be
6501 provided in separate binary packages with "-75dpi" or "-100dpi"
6502 appended to the names of the packages containing the
6503 corresponding fonts.
6506 Fonts destined for the <tt>misc</tt> subdirectory should
6507 not be included in the same package as 75dpi or 100dpi fonts;
6508 instead, they should be provided in a separate package with
6509 "-misc" appended to its name.
6512 Font packages <em>must not</em> provide the files
6513 <tt>fonts.dir</tt>, <tt>fonts.alias</tt>, or
6514 <tt>fonts.scale</tt> in a font directory.
6517 <tt>fonts.dir</tt> files must not be provided at
6521 <tt>fonts.alias</tt> and <tt>fonts.scale</tt>
6522 files, if needed, should be provided in the
6524 <tt>/etc/X11/fonts/<em>fontdir</em>/<em>package</em>.<em>extension</em></tt>,
6525 where <em>fontdir</em> is the name of the
6527 <tt>/usr/X11R6/lib/X11/fonts/</tt> where the
6528 package's corresponding fonts are stored (e.g.,
6529 <tt>75dpi</tt> or <tt>misc</tt>),
6530 <em>package</em> is the name of the package that
6531 provides these fonts, and <em>extension</em> is
6532 either <tt>scale</tt> or <tt>alias</tt>,
6533 whichever corresponds to the file
6539 Font packages must declare a dependency on
6540 <tt>xutils</tt> and, in the package
6541 post-installation and post-removal scripts, invoke the
6542 <tt>mkfontdir</tt> command on each directory into
6543 which they installed fonts.
6546 Font packages that provide one or more
6547 <tt>fonts.scale</tt> files as described above must declare a
6548 versioned dependency on <tt>xutils (>=
6549 4.0.2)</tt> and invoke <tt>update-fonts-scale</tt> on each
6550 directory into which they installed fonts
6551 <em>before</em> invoking <tt>mkfontdir</tt> on that
6552 directory. This invocation must occur in both the
6553 post-installation and post-removal scripts.
6556 Font packages that provide one or more
6557 <tt>fonts.alias</tt> files as described above must
6558 declare a versioned dependency on <tt>xutils
6559 (>= 4.0.2)</tt> and, in the package
6560 post-installation and post-removal scripts, invoke
6561 <tt>update-fonts-alias</tt> on each directory into
6562 which they installed fonts.
6565 Font packages must not provide alias names for the
6566 fonts they include which collide with alias names already in
6567 use by fonts already packaged.
6570 Font packages must not provide fonts with the same XLFD
6571 registry name as another font already packaged.
6577 <em>Application defaults</em> files must be installed in the
6578 directory <tt>/etc/X11/app-defaults/</tt> (use of a
6579 localized subdirectory of <tt>/etc/X11/</tt> as described in
6580 the <em>X Toolkit Intrinsics - C Language Interface</em>
6581 manual is also permitted). They must be registered as
6582 <em>conffile</em>s or handled as configuration files. For
6583 programs that are not linked against the X Toolkit (Xt)
6584 library, customization of programs' X resources may also be
6585 supported with the provision of a file with the same name as
6586 that of the package placed in the
6587 <tt>/etc/X11/Xresources/</tt> directory, which must
6588 registered as a <em>conffile</em> or handled as a
6589 configuration file. <em>Important:</em> packages that
6590 install files into the <tt>/etc/X11/Xresources/</tt>
6591 directory <em>must</em> declare a conflict with <tt>xbase
6592 (<< 3.3.2.3a-2)</tt>; if this is not done it is
6593 possible for the installing package to destroy a
6594 previously-existing <tt>/etc/X11/Xresources</tt> file which
6595 had been customized by the system administrator.
6599 <em>Packages using the X Window System should abide by the FHS
6600 standard whenever possible</em>; they should install binaries,
6601 libraries, manual pages, and other files in FHS-mandated
6602 locations wherever possible. This means that files must
6603 not be installed into <tt>/usr/X11R6/bin/</tt>,
6604 <tt>/usr/X11R6/lib/</tt>, or <tt>/usr/X11R6/man/</tt> unless
6605 this is necessary for the package to operate properly.
6606 Configuration files for window managers and display managers
6607 should be placed in a subdirectory of <tt>/etc/X11/</tt>
6608 corresponding to the package name due to these programs'
6609 tight integration with the mechanisms of the X Window
6610 System. Application-level programs should use the
6611 <tt>/etc/</tt> directory unless otherwise mandated by
6612 policy. The installation of files into subdirectories of
6613 <tt>/usr/X11R6/include/X11/</tt> and
6614 <tt>/usr/X11R6/lib/X11/</tt> is permitted but discouraged;
6615 package maintainers should determine if subdirectories of
6616 <tt>/usr/lib/</tt> and <tt>/usr/share/</tt> can be used
6617 instead (symlinks from the X11R6 directories to
6618 FHS-compliant locations is encouraged if the program is not
6619 easily configured to look elsewhere for its files).
6620 Packages must not provide -- or install files into -- the
6621 directories <tt>/usr/bin/X11/</tt>,
6622 <tt>/usr/include/X11/</tt>, or <tt>/usr/lib/X11/</tt>.
6623 Files within a package should, however, make reference to
6624 these directories, rather than their X11R6-named
6625 counterparts <tt>/usr/X11R6/bin/</tt>,
6626 <tt>/usr/X11R6/include/X11/</tt>, and
6627 <tt>/usr/X11R6/lib/X11/</tt>, if the resources being
6628 referred to have not been moved to FHS-compliant locations.
6632 <em>Programs that require the non-DFSG-compliant OSF/Motif
6633 library</em> should be compiled against and tested with
6634 LessTif (a free re-implementation of Motif) instead. If the
6635 maintainer judges that the program or programs do not work
6636 sufficiently well with LessTif to be distributed and
6637 supported, but do so when compiled against Motif, then two
6638 versions of the package should be created; one linked
6639 statically against Motif and with <tt>-smotif</tt> appended
6640 to the package name, and one linked dynamically against
6641 Motif and with <tt>-dmotif</tt> appended to the package
6642 name. Both Motif-linked versions are dependent upon
6643 non-DFSG-compliant software and thus cannot be uploaded to
6644 the main distribution; if the software is itself
6645 DFSG-compliant it may be uploaded to the contrib
6646 distribution. While known existing versions of OSF/Motif
6647 permit unlimited redistribution of binaries linked against
6648 the library (whether statically or dynamically), it is the
6649 package maintainer's responsibility to determine whether
6650 this is permitted by the license of the copy of OSF/Motif in
6651 his or her possession.
6656 <heading>Perl programs and modules</heading>
6658 Perl programs and modules should follow the current Perl
6659 policy as defined in the file found on
6660 <ftpsite>ftp.debian.org</ftpsite> in
6661 <ftppath>/debian/doc/package-developer/perl-policy.txt.gz</ftppath>
6662 or your local mirror. In addition, it is included in the
6663 <tt>debian-policy</tt> package.
6668 <heading>Emacs lisp programs</heading>
6671 Please refer to the `Debian Emacs Policy' (documented in
6672 <tt>debian-emacs-policy.gz</tt> of the
6673 <prgn>emacsen-common</prgn> package) for details of how to
6674 package emacs lisp programs.</p></sect>
6678 <heading>Games</heading>
6681 The permissions on /var/games are 755
6682 <tt>root.root</tt>.</p>
6685 Each game decides on its own security policy.</p>
6688 Games which require protected, privileged access to
6689 high-score files, savegames, etc., may be made
6690 set-<em>group</em>-id (mode 2755) and owned by
6691 <tt>root.games</tt>, and use files and directories with
6692 appropriate permissions (770 <tt>root.games</tt>, for
6693 example). They must not be made
6694 set-<em>user</em>-id, as this causes security problems. (If
6695 an attacker can subvert any set-user-id game they can
6696 overwrite the executable of any other, causing other players
6697 of these games to run a Trojan horse program. With a
6698 set-group-id game the attacker only gets access to less
6699 important game data, and if they can get at the other
6700 players' accounts at all it will take considerably more
6704 Some packages, for example some fortune cookie programs, are
6705 configured by the upstream authors to install with their
6706 data files or other static information made unreadable so
6707 that they can only be accessed through set-id programs
6708 provided. You should not do this in a Debian package: anyone can
6709 download the <tt>.deb</tt> file and read the data from it,
6710 so there is no point making the files unreadable. Not
6711 making the files unreadable also means that you don't have
6712 to make so many programs set-id, which reduces the risk of a
6716 As described in the FHS, binaries of games should be
6717 installed in the directory <tt>/usr/games</tt>. This also
6718 applies to games that use the X Window System. Manual pages
6719 for games (X and non-X games) should be installed in
6720 <tt>/usr/share/man/man6</tt>.</p>
6724 <chapt><heading>Documentation</heading>
6728 <heading>Manual pages</heading>
6731 You should install manual pages in <prgn>nroff</prgn> source
6732 form, in appropriate places under <tt>/usr/share/man</tt>. You
6733 should only use sections 1 to 9 (see the FHS for more
6734 details). You must not install a preformatted `cat
6738 Each program, utility, and function should have an
6739 associated manpage included in the same package. It is
6740 suggested that all configuration files also have a manual
6741 page included as well.
6745 If no manual page is available for a particular program,
6746 utility, function or configuration file and this is reported as a bug on
6747 debian-bugs, a symbolic link from the requested manual page
6748 to the <manref name="undocumented" section="7"> manual page
6749 may be provided. This symbolic link can be created from
6750 <tt>debian/rules</tt> like this:
6752 ln -s ../man7/undocumented.7.gz \
6753 debian/tmp/usr/share/man/man[1-9]/the_requested_manpage.[1-9].gz
6755 This manpage claims that the lack of a manpage has been
6756 reported as a bug, so you may only do this if it really has
6757 (you can report it yourself, if you like). Do not close the
6758 bug report until a proper manpage is available.</p>
6761 You may forward a complaint about a missing manpage to the
6762 upstream authors, and mark the bug as forwarded in the
6763 Debian bug tracking system. Even though the GNU Project do
6764 not in general consider the lack of a manpage to be a bug,
6765 we do--if they tell you that they don't consider it a bug
6766 you should leave the bug in our bug tracking system open
6770 Manual pages should be installed compressed using <tt>gzip
6774 If one manpage needs to be accessible via several names it
6775 is better to use a symbolic link than the <tt>.so</tt>
6776 feature, but there is no need to fiddle with the relevant
6777 parts of the upstream source to change from <tt>.so</tt> to
6778 symlinks--don't do it unless it's easy. You should not create hard
6779 links in the manual page directories, nor put
6780 absolute filenames in <tt>.so</tt> directives. The filename
6781 in a <tt>.so</tt> in a manpage should be relative to the
6782 base of the manpage tree (usually
6783 <tt>/usr/share/man</tt>).</p></sect>
6787 <heading>Info documents</heading>
6790 Info documents should be installed in <tt>/usr/share/info</tt>.
6791 They should be compressed with <tt>gzip -9</tt>.</p>
6794 Your package should call <prgn>install-info</prgn> to update the Info
6796 file, in its post-installation script:
6798 install-info --quiet --section Development Development \
6799 /usr/share/info/foobar.info
6803 It is a good idea to specify a section for the location of
6804 your program; this is done with the <tt>--section</tt>
6805 switch. To determine which section to use, you should look
6806 at <tt>/usr/share/info/dir</tt> on your system and choose the most
6807 relevant (or create a new section if none of the current
6808 sections are relevant). Note that the <tt>--section</tt>
6809 flag takes two arguments; the first is a regular expression
6810 to match (case-insensitively) against an existing section,
6811 the second is used when creating a new one.</p>
6814 You should remove the entries in the pre-removal script:
6816 install-info --quiet --remove /usr/share/info/foobar.info
6820 If <prgn>install-info</prgn> cannot find a description entry
6821 in the Info file you must supply one. See <manref
6822 name="install-info" section="8"> for details.</p>
6826 <heading>Additional documentation</heading>
6829 Any additional documentation that comes with the package may
6830 be installed at the discretion of the package maintainer.
6831 Text documentation should be installed in a directory
6832 <tt>/usr/share/doc/<var>package</var></tt>, where
6833 <var>package</var> is the name of the package, and
6834 compressed with <tt>gzip -9</tt> unless it is small.</p>
6837 If a package comes with large amounts of documentation which
6838 many users of the package will not require you should create
6839 a separate binary package to contain it, so that it does not
6840 take up disk space on the machines of users who do not need
6841 or want it installed.</p>
6844 It is often a good idea to put text information files
6845 (<tt>README</tt>s, changelogs, and so forth) that come with
6846 the source package in <tt>/usr/share/doc/<var>package</var></tt>
6847 in the binary package. However, you don't need to install
6848 the instructions for building and installing the package, of
6852 Files in <tt>/usr/share/doc</tt> should not be referenced by
6853 any program, and the system administrator should be able to
6854 delete them without causing any programs to break. Any files
6855 that are referenced by programs but are also useful as
6856 standalone documentation should be installed under
6857 <tt>/usr/share/<package>/</tt> and symlinked in
6858 <tt>/usr/share/doc/<package>/</tt>.
6864 <heading>Accessing the documentation</heading>
6867 Former Debian releases placed all additional documentation
6868 in <tt>/usr/doc/<var>package</var></tt>. To realize a
6870 <tt>/usr/share/doc/<var>package</var></tt>, each package
6871 must maintain a symlink <tt>/usr/doc/<var>package</var></tt>
6872 that points to the new location of its documentation in
6873 <tt>/usr/share/doc/<var>package</var></tt><footnote>These
6874 symlinks will be removed in the future, but they have to be
6875 there for compatibility reasons until all packages have
6876 moved and the policy is changed accordingly.</footnote>.
6877 The symlink must be created when the package is installed;
6878 it cannot be contained in the package itself due to problems
6879 with <prgn>dpkg</prgn>. One reasonable way to accomplish
6880 this is to put the following in the package's
6881 <prgn>postinst</prgn>:
6883 if [ "$1" = "configure" ]; then
6884 if [ -d /usr/doc -a ! -e /usr/doc/#PACKAGE# \
6885 -a -d /usr/share/doc/#PACKAGE# ]; then
6886 ln -sf ../share/doc/#PACKAGE# /usr/doc/#PACKAGE#
6890 And the following in the package's <prgn>prerm</prgn>:
6892 if [ \( "$1" = "upgrade" -o "$1" = "remove" \) \
6893 -a -L /usr/doc/#PACKAGE# ]; then
6894 rm -f /usr/doc/#PACKAGE#
6901 <heading>Preferred documentation formats</heading>
6904 The unification of Debian documentation is being carried out
6908 If your package comes with extensive documentation in a
6909 mark up format that can be converted to various other formats
6910 you should if possible ship HTML versions in a binary
6911 package, in the directory
6912 <tt>/usr/share/doc/<var>appropriate package</var></tt> or its
6915 <p>The rationale: The important thing here is that HTML
6916 docs should be available in <em>some</em> package, not
6917 necessarily in the main binary package, though. </p>
6922 Other formats such as PostScript may be provided at your
6926 <sect id="copyrightfile">
6927 <heading>Copyright information</heading>
6930 Every package must be accompanied by a verbatim copy of its
6931 copyright and distribution license in the file
6932 /usr/share/doc/<package>/copyright. This file must
6933 neither be compressed nor be a symbolic link.</p>
6936 In addition, the copyright file must say where the upstream
6937 sources (if any) were obtained, and should explain briefly what
6938 modifications were made in the Debian version of the package
6939 compared to the upstream one. It should name the original
6940 authors of the package and the Debian maintainer(s) who were
6941 involved with its creation.</p>
6944 A copy of the file which will be installed in
6945 <tt>/usr/share/doc/<var>package</var>/copyright</tt> should be
6946 in <tt>debian/copyright</tt>.</p>
6950 /usr/share/doc/<package> may be a symbolic link to a
6951 directory in /usr/share/doc only if two packages both come from
6952 the same source and the first package has a "Depends"
6953 relationship on the second. These rules are important
6954 because copyrights must be extractable by mechanical
6958 Packages distributed under the UCB BSD license, the Artistic
6959 license, the GNU GPL, and the GNU LGPL should refer to the
6960 files /usr/share/common-licenses/BSD,
6961 /usr/share/common-licenses/Artistic,
6962 /usr/share/common-licenses/GPL, and
6963 /usr/share/common-licenses/LGPL.
6966 Why "licenses" and not "copyright"? Because
6967 <tt>/usr/doc/copyright</tt> used to contain all the
6968 copyright files, plus the four common licenses GPL,
6969 LGPL, Artistic and BSD. Now individual copyright files
6970 for packages are no longer in a common directory. Once
6971 <tt>/usr/doc/copyright</tt> is almost empty it makes
6972 sense to rename "copyright" to "licenses"
6975 Why "common-licenses" and not "licenses"? Because if I
6976 put just "licenses" I'm sure I will receive a bug report
6977 saying "license foo is not included in the licenses
6978 directory. They are not all the licenses, just a few
6979 common ones. I could use /usr/share/doc/common-licenses
6980 but I think this is too long, and, after all, the GPL
6981 does not "document" anything, it is merely a license.
6987 You should not use the copyright file as a general <tt>README</tt>
6988 file. If your package has such a file it should be
6989 installed in <tt>/usr/share/doc/<var>package</var>/README</tt> or
6990 <tt>README.Debian</tt> or some other appropriate place.</p>
6994 <heading>Examples</heading>
6997 Any examples (configurations, source files, whatever),
6998 should be installed in a directory
6999 <tt>/usr/share/doc/<var>package</var>/examples</tt>. These
7000 files should not be referenced by any program--they're there
7001 for the benefit of the system administrator and users, as
7002 documentation only. Architecture-specific example files
7003 should be installed in a directory
7004 <tt>/usr/lib/<var>package</var>/examples</tt>, and files in
7005 <tt>/usr/share/doc/<var>package</var>/examples</tt> symlink
7006 to files in it. Or the latter directory may be a symlink to
7010 <sect id="instchangelog">
7011 <heading>Changelog files</heading>
7014 Packages that are not Debian-native must contain a copy of
7015 <tt>debian/changelog</tt> file from the Debian source tree
7016 in <tt>/usr/share/doc/<var>package</var></tt> as
7017 <tt>changelog.Debian.gz</tt>. If an upstream changelog is
7018 available, it should be accessible as
7019 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt> in
7020 plain text. If the upstream changelog is distributed in
7021 HTML, it should be made available in that form as
7022 <tt>/usr/share/doc/<var>package</var>/changelog.html.gz</tt>
7023 and the <tt>changelog.gz</tt> should be generated using, eg,
7024 <tt>lynx -dump -nolist</tt>. If the upstream changelog files
7025 do not already conform to this naming convention, then this
7026 may be achieved either by renaming the files, or adding a
7027 symbolic link, at the maintainer's discretion.
7030 Rationale: People should not have to look into two
7031 places for upstream changelogs merely because they are
7039 All these files should be installed compressed using <tt>gzip -9</tt>,
7040 as they will become large with time even if they start out
7045 If the package has only one changelog which is used both as
7046 the Debian changelog and the upstream one because there is
7047 no separate upstream maintainer then that changelog should
7048 usually be installed as
7049 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt>; if
7050 there is a separate upstream maintainer, but no upstream
7051 changelog, then the Debian changelog should still be called
7052 <tt>changelog.Debian.gz</tt>.</p>